* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download McSorley 2013 IJP - Rick Maizels` Group
Survey
Document related concepts
Lymphopoiesis wikipedia , lookup
Monoclonal antibody wikipedia , lookup
Autoimmunity wikipedia , lookup
Immune system wikipedia , lookup
Immunosuppressive drug wikipedia , lookup
Adoptive cell transfer wikipedia , lookup
Adaptive immune system wikipedia , lookup
Cancer immunotherapy wikipedia , lookup
Molecular mimicry wikipedia , lookup
DNA vaccination wikipedia , lookup
Polyclonal B cell response wikipedia , lookup
Innate immune system wikipedia , lookup
Transcript
International Journal for Parasitology 43 (2013) 301–310 Contents lists available at SciVerse ScienceDirect International Journal for Parasitology journal homepage: www.elsevier.com/locate/ijpara Invited Review Immunomodulation by helminth parasites: Defining mechanisms and mediators Henry J. McSorley ⇑, James P. Hewitson, Rick M. Maizels Institute of Immunology and Infection Research, University of Edinburgh, UK a r t i c l e i n f o Article history: Received 16 October 2012 Received in revised form 28 November 2012 Accepted 29 November 2012 Available online 3 January 2013 Keywords: Excretory-secretory products Hygiene hypothesis Immunomodulators a b s t r a c t Epidemiological and interventional human studies, as well as experiments in animal models, strongly indicate that helminth parasitic infections can confer protection from immune dysregulatory diseases such as allergy, autoimmunity and colitis. Here, we review the immunological pathways that helminths exploit to downregulate immune responses, both against bystander specificities such as allergens and against antigens from the parasites themselves. In particular, we focus on a highly informative laboratory system, the mouse intestinal nematode, Heligmosomoides polygyrus, as a tractable model of host-parasite interaction at the cellular and molecular levels. Analysis of the molecules released in vitro (as excretorysecretory products) and their cellular targets is identifying individual parasite molecules and gene families implicated in immunomodulation, and which hold potential for future human therapy of immunopathological conditions. Ó 2013 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved. 1. Introduction The increasing tempo of reported beneficial effects of helminth infections in the prevention or suppression of immune dysregulatory diseases (reviewed by Elliott and Weinstock, 2009; Harnett and Harnett, 2010; Danilowicz-Luebert et al., 2011; McSorley and Maizels, 2012) has excited attention on the possible molecular products of parasites that might be applied to treatment of allergy, autoimmunity and colitis. It is generally assumed that such molecules are released from living parasites in situ and can be collected as excretory-secretory (ES) products from helminths cultivated in vitro (Hewitson et al., 2009). These products may exert their effects directly on cells of the host immune system, or indirectly by invoking the immune system’s own down-regulatory mechanisms. Helminth parasites are an evolutionarily ancient and diverse group of metazoan organisms and yet there is a striking convergence in similar modes of immune modulation observed in clinical and experimental studies. Parasite suppression of immunopathology involves CD4+ regulatory T cells (Tregs, either Foxp3+ or Foxp3 ), CD8+ Tregs, regulatory B cells, IL-4-responsive cells, TGF-b, IL-10 and Th2 cytokines (McSorley and Maizels, 2012). Thus distantly-related parasites have independently evolved to exploit a range of host immunoregulatory mechanisms to their own advantage, and by invoking generic suppressive pathways can also sup- ⇑ Corresponding author. Address: Institute of Immunology and Infection Research, University of Edinburgh, Ashworth Laboratories, West Mains Road, Edinburgh EH9 3JT, UK. Tel.: +44 1316506763. E-mail addresses: [email protected], [email protected] (H.J. McSorley). press bystander responses to allergens and self-antigens (Allen and Maizels, 2011). The suppression of human immunopathology by live parasitic infections is being extensively tested (Fleming, 2011; Jouvin and Kinet, 2012), and even offered to patients on a commercial basis. However, real practical and ethical considerations are likely to present major obstacles to live infection therapy being commonly used. First, there is a logistical constraint on the scale of live parasite production, which would not satisfy the demand from large numbers of patients with allergic and autoimmune disorders. Secondly, we understand little about the variation in human responses to helminths, although it is recognised that naturally-acquired infections produce a spectrum of outcomes from asymptomatic to severe pathology, which is likely to be genetically determined (Quinnell, 2003). Perhaps most importantly, live helminth treatment is essentially empirical and is currently applied with no known mechanism of action. Hence, there is a great need for the definition and development of parasite-derived immunomodulators as novel therapeutic agents, with known modes of action and understanding of responses in the genetically heterogeneous human population. In order to develop non-living parasite-derived therapeutic agents, the molecular motifs that are responsible for protection from immunopathology must first be identified, and the host pathways that are targeted likewise defined. Across a broad range of parasite species, a substantial number of studies have now investigated the immunomodulatory mechanisms of parasite-derived soluble molecules, ranging from total mixtures of parasite extracts, through secretory products and biochemically-isolated fractions, to laboratory-produced recombinant proteins and synthetic glycans (Hewitson et al., 2009; Harnett and Harnett, 2010; 0020-7519/$36.00 Ó 2013 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijpara.2012.11.011 302 H.J. McSorley et al. / International Journal for Parasitology 43 (2013) 301–310 Danilowicz-Luebert et al., 2011; McSorley and Maizels, 2012). These entities have been screened across a spectrum of targets ranging from the most reductionist level of testing single molecules in vitro on individual innate and adaptive immune cell types through to complex models of immunopathology in vivo. In the following sections, we discuss each of these fascinating interactions in turn. 2. Innate cells The initiating step in the adaptive immune response to infection is an antigen presenting cell (APC, usually a dendritic cell – DC), taking up, processing and presenting antigen to T cells. DCs upregulate expression of surface ligands and soluble mediators which activate antigen-specific T cells through their costimulatory and cytokine receptors. This interaction can also direct the qualitative nature of the response, for example towards a dominant Th1 or Th2 mode (Moser and Murphy, 2000), or indeed into the regulatory pathway of Foxp3+ Tregs (Yamazaki et al., 2006). Many parasite products can interfere with this process, resulting in an anergic or tolerogenic DC phenotype, or preventing the emergence of an inflammatory Th1/17 outcome. Human or mouse DCs, when cultured with Schistosoma mansoni Soluble Egg Antigen (SEA), do not undergo classical maturation of costimulatory ligand expression, but can induce Th2 responses in vitro or when transferred to a naïve host, in a MyD88- and IL-4-independent manner (Jankovic et al., 2004). Similarly, injection of Nippostronglyus brasiliensis adult (Holland et al., 2000) or larval (Marsland et al., 2005) ES (NES) products induces a Th2 response in an IL-4-, IL-5- and B cellindependent but class II MHC-dependent manner (Holland et al., 2005). As in the case with SEA, Th2 induction can be replicated in vivo by administration of NES-pulsed DCs (Balic et al., 2004) but not basophils (Smith et al., 2012). Similarly, Fasciola hepatica ES-pulsed DCs can drive Th2 differentiation of T cells in vitro (Falcon et al., 2010). The Th2-inducing effects of parasite products are dominant even if helminth antigen-pulsed DCs are cocultured with a strongly proinflammatory stimulus such as lipopolysaccharide (LPS) (Everts et al., 2009; Jankovic et al., 2004). Indeed, suppression of the inflammatory (Th1) pathway is a common feature of helminth products, including ES from Heligmosomoides polygyrus (Segura et al., 2007; Massacand et al., 2009), Echinococcus multilocularis (Nono et al., 2012), N. brasiliensis (Massacand et al., 2009), Taenia crassiceps (Terrazas et al., 2011), Trichinella spiralis (Aranzamendi et al., 2012; Bai et al., 2012) and Trichuris suis (Kuijk et al., 2012), as well as tegumental or ES antigens from F. hepatica (Hamilton et al., 2009; Falcon et al., 2010). The suppressive activity is evident through ablation of IL-12 production and was retained after heattreatment of products in some cases (Aranzamendi et al., 2012; Massacand et al., 2009), indicating a role for heat-stable glycans. Recently, the molecules responsible for these effects have begun to be identified. The Th2-inducing ability of SEA can be partially attributed to a single S. mansoni product: x-1, a T2 RNase glycoprotein (Everts et al., 2009; Steinfelder et al., 2009). x-1 binds to, and is internalised by, DCs through the mannose receptor in a carbohydrate-dependent manner, and x-1 then suppresses protein synthesis through degradation of intracellular RNA. This results in suppression of costimulatory molecule and IL-12 expression; as a consequence a Th2 response is favoured (Everts et al., 2012). Although T2 RNases are present in other schistosomes (Zhou et al., 2009; Young et al., 2012), and more distantly related parasitic helminths (such as Brugia malayi, Loa loa and Ascaris suum (Hillwig et al., 2009)), it is as yet unknown whether this is a common mechanism of Th2 induction by parasites. While x-1 disables DC function, and thereby Th1 induction, by suppression of global protein expression, E. multilocularis ES prevents inflammatory responses by inducing DC apoptosis (Nono et al., 2012). A similar phenomenon occurs in human DCs cocultivated with live microfilariae (MF) of B. malayi. The pathway activated by the MF, and probably by a product released from the parasites, involved both TNF and TRAIL signalling (Semnani et al., 2008). Induction of apoptosis to prevent potentially damaging cellular immune responses is in fact a widely-observed effect of helminth products, as F. hepatica ES products induce both macrophage and eosinophil apoptosis (Guasconi et al., 2012; Serradell et al., 2007), while S. mansoni SEA induces apoptosis of T cells in a subset of infected individuals (Carneiro-Santos et al., 2000). Other APC-modulating factors are also active on macrophages. For instance, Strongyloides ratti ES products contain the heat-shock proteins, Sra-HSP-17.1 and Sra-HSP-17.2, which bind monocytes, macrophages and intestinal epithelial cells, and induce IL-10 production by blood monocytes (Younis et al., 2011). Furthermore, a product of the trematode F. hepatica, called FhHDM-1 (F. hepatica Helminth Defense Molecule-1), binds LPS to prevent it stimulating inflammatory responses (Robinson et al., 2011). FhHDM-1 also incapacitates macrophage vacuolar ATPases, resulting in suppression of endosome acidification and defective antigen presentation (Robinson et al., 2012). Interestingly this protein, which shows homology to human cathelicidins, has homologues in many other human-infective trematodes including the schistosomes (Robinson et al., 2011), so it may be a common trematode immunomodulator. Peroxiredoxin molecules from F. hepatica and S. mansoni also show Th2-inducing ability and induce alternative activation of macrophages (Donnelly et al., 2008). This activation phenotype is associated with Th2 responses and can be immunosuppressive (Gordon, 2003). As mentioned above, many of the suppressive functions of parasite products are heat-stable, indicating they may be of carbohydrate nature. Elucidation of immunomodulatory carbohydrates from helminths has been hindered by a lack of tools for identification, manipulation and production of these molecules, however recent studies have begun to address this area (Maizels and Hewitson, 2012). The lacto-N-fucopentaose III (LNFPIII) carbohydrate, which is present in S. mansoni egg secretions, induces alternative activation of macrophages in an IL-4R-independent manner (Atochina et al., 2008; Bhargava et al., 2012), as well as skewing responses towards Th2 (Harn et al., 2009), and inducing IL-10 production from macrophages and DCs (Bhargava et al., 2012). The LNFPIII glyan contains Lewisx motifs, which are thought to be responsible for its function by signalling through C-type lectin receptors (Harn et al., 2009). Human breast milk also contains LNFPIII, where it is thought to have similar immunomodulatory effects as in schistosome secretions (Bhargava et al., 2012). Furthermore, a recent report showed that chitohexaose, a glycan present on products from filarial nematodes such as Setaria digitaria and Brugia pahangi, competes for binding to TLR-4, suppressing LPS responses and inducing alternative activation of macrophages (Panda et al., 2012), and may represent a common heat-stable parasite-derived suppressor of TLR signalling. Thus a range of molecular products from diverse parasites share a common ability to block inflammatory responses and induce Th2 through modulation of DC and macrophage stimulation. Basophils are innate cells capable of producing large amounts of IL-4 after cross-linking of surface-bound IgE. This normally occurs only in the presence of circulating antigen-specific IgE, following a Th2-dominated response to a parasite. However, schistosomes exploit this mechanism to induce IL-4 release by basophils even in a primary infection, prior to the development of a strong IgE response against parasite antigens. IPSE/a-1 is a protein produced by S. mansoni eggs which cross-links endogenous surface-bound IgE on baso- H.J. McSorley et al. / International Journal for Parasitology 43 (2013) 301–310 phils in an antigen non-specific manner. This interaction leads to robust production of IL-4 and amplifies the Th2 response around deposited eggs during S. mansoni infection (Schramm et al., 2007). In schistosome infections, the initial Th1-dominated immune response to schistosomes switches to Th2 on egg deposition (Pearce and MacDonald, 2002). This switch may be advantageous to the parasite as the Th2 bias is thought to facilitate either or both egg transit into the intestinal lumen and tissue repair of resulting lesions. If the switch to Th2 does not occur, as in IL-4/IL-13 double deficient mice, acute mortality results (Fallon et al., 2000). In the later stages of chronic S. mansoni infection, however, the Th2 response is downregulated, suppressing damage to the parasite and fibrosis in the host. In chronic S. mansoni or Litomosoides sigmodontis infection, basophils are found to be hyporesponsive to stimulation, by a largely IL-10-dependent mechanism. When L. sigmodontis ES products were added to normal basophils in vitro, they were also rendered hyporesponsive (Larson et al., 2012). In contrasting ways, therefore, helminth products can ‘‘tune’’ basophil responses to optimise their own (and their host’s) survival. Further complexity is added as both IPSE and x-1 have recently been shown to be directly toxic to hepatocytes in vitro, likely promoting the liver pathology seen in schistosome infection (Abdulla et al., 2011). IPSE also has a mammalian cell internalisation sequence and DNA-binding ability, so may modulate intracellular signalling events and even directly influence host gene expression (Kaur et al., 2011). These data indicate that even a single helminth product can have multiple effects, depending on cell type and context. A similar contrast is seen in eosinophil responses; most helminth infections and many helminth ES materials stimulate eosinophilia, however during mouse models of asthma one of the major features of suppression by helminth infection is reduced eosinophilia (as discussed in Section 5, below). In particular, certain ES products can directly suppress eosinophil responses. For instance, Necator americanus ES products contain a protease which cleaves and inactivates eotaxin, preventing the recruitment of eosinophils (Culley et al., 2000), while H. polygyrus ES (HES) products prevent eosinophilia in allergen-sensitised mice (McSorley et al., 2012). In the case of N. americanus, the Ancylostoma secreted protein (ASP)-2 ES protein has neutrophil chemoattractant functions, and has a charge distribution similar to mammalian chemokines (Asojo et al., 2005; Bower et al., 2008). Thus N. americanus may suppress the recruitment of potentially damaging eosinophils while encouraging the recruitment of ineffective neutrophils. 3. T cells Adaptive immune responses are orchestrated by CD4+ T cells, and many studies have addressed immunomodulatory effects of parasite products on T cells, effects which are exerted through a variety of direct and indirect pathways. The most prominent indirect effect is through altering DC function. DCs exposed to ES products from T. spiralis or E. multilocularis not only lose their responsiveness to LPS (as discussed above) but switch to inducing Th2 and Foxp3+ Treg cells in vitro (Gruden-Movsesijan et al., 2011; Aranzamendi et al., 2012; Nono et al., 2012). Likewise, in DC-T cell cocultures, x-1 from S. mansoni SEA can induce Foxp3+ Treg, through induction of TGF-b and retinoic acid-activating enzymes (Zaccone et al., 2011). As well as inducing Th2 responses when transferred in vivo, HES product-pulsed DCs, when cultured with T cells, suppress both IFN-c and IL-4 in favour of IL-10 and confer a suppressive phenotype on T cells, although in this study they remained Foxp3-negative (Segura et al., 2007). More direct effects of ES materials on T cells are evident in the ability of HES products to induce Foxp3 expression in naïve T cells 303 even in the absence of DCs or other accessory cells (Grainger et al., 2010). Induced Foxp3+ T cells are functional and, when transferred to uninfected mice, protect against airway allergy. Notably, in vitro conversion of naïve T cells is effected by ligation of the TGF-b receptor on T cells, indicating that HES products contain a molecular mimic of this mammalian suppressive cytokine. This activity is, moreover, not unique to HES products as ES products from the related ruminant nematode, Teladorsagia circumcincta, display a similar Treg-inducing property. In a distinct fashion, ES products from Spirometra mansoni has been shown not to directly induce Tregs, but to enhance their suppressive function in vitro (Kim et al., 2012a). Suppression of early innate responses and induction of Tregs specific to helminth and bystander antigens suggests the intriguing possibility that helminth products could be used to induce lasting suppression and/or tolerance to potentially pathogenic allergens or autoantigens. 4. The hygiene hypothesis Almost 25 years ago, Strachan proposed that exposure to infections in early life protected children against airway allergy in the form of seasonal rhinitis (Strachan, 1989). His original ‘Hygiene Hypothesis’ suggested that early-life infections stimulated correct development of the immune system and their absence predisposed towards hyperactivity and inappropriate immune responses such as those seen in allergy. The role of helminth infections in this interaction has received much interest as these infections were common in the developed world up to a century ago but have subsequently been largely eradicated. Over this same time period, an epidemic of immunopathological diseases such as allergic asthma has affected the developed nations. Epidemiological studies of atopy (Feary et al., 2011) or asthma (Leonardi-Bee et al., 2006) suggest that current parasitic infection has a protective effect. Hence, the protective effect of infections may not only be exerted in at an early age but by acquiring infections in later life. Subsequently, the Hygiene Hypothesis was further extended to other examples of immunopathology such as autoimmunity and inflammatory bowel disease (IBD) (Elliott and Weinstock, 2012). This theory has led to a series of clinical trials and studies of live parasitic infection in individuals with IBD such as Crohn’s disease (Summers et al., 2003, 2005a; Croese et al., 2006), ulcerative colitis (Summers et al., 2003, 2005b; Broadhurst et al., 2010) or coeliac disease (Daveson et al., 2011; McSorley et al., 2011); autoimmune diseases such as multiple sclerosis (Correale and Farez, 2007, 2011; Correale et al., 2008; Fleming et al., 2011; Benzel et al., 2012); and allergic diseases such as seasonal rhinitis (Blount et al., 2009; Feary et al., 2009; Bager et al., 2010). Furthermore, mouse models of immunopathological disease have confirmed the protective effect of helminth infection (reviewed in McSorley and Maizels, 2012) To identify the molecules and mechanisms used by parasites to suppress these responses, parasite products have been administered in a range of these immunopathology models, to attempt to replicate suppression in parasitic infection. 5. Airway allergy (asthma) Asthma is an allergic disease that can be modelled in mice by administration of a model allergen (such as ovalbumin, OVA) in an alum adjuvant (sensitisation), followed by recall of a Th2 response by allergen administration to the airways (challenge), resulting in recruitment of eosinophils, production of Th2 cytokines and airway hyperresponsiveness to stimuli (Bates et al., 2009). A range of helminth products are able to interfere with the development or expression of allergic reactions. Thus, administration of A. 304 H.J. McSorley et al. / International Journal for Parasitology 43 (2013) 301–310 suum adult worm antigen (Lima et al., 2002), SEA (Yang et al., 2007), NES products (Trujillo-Vargas et al., 2007), Toxascaris leonina ES products (Lee et al., 2008) or HES products (McSorley et al., 2012) at sensitisation result in suppression of the allergic response at challenge. Using NES products, the mechanism of suppression was found to be independent of IL-10 and TLR 2 or 4 signalling, but required conformationally-intact protein as activity was ablated on heat treatment (Trujillo-Vargas et al., 2007). In contrast, the suppressive factor in HES products, when given at sensitisation, was heat-stable (McSorley et al., 2012), and could not be replicated by administration of mammalian TGF-b at the level of activity found in HES products (Grainger et al., 2010). As these products modulate the recall response when given at the initiation of the allergic immune response, it seems likely they are interfering with the early events in antigen presentation, T cell proliferation or Th2 differentiation. HES products can also suppress airway inflammation when administered into the airways at OVA challenge (McSorley et al., 2012), in a setting which reflects inhibition of an established Th2 response. Using this protocol, suppression was ablated by heat treatment of HES products, indicating it is due to a different product than that which suppresses when HES products were administered at sensitisation, and that the heat-labile product suppresses cellular recruitment or Th2 effector mechanisms. Recent studies on allergic airway inflammation have started to address the immunomodulatory effects of individual parasite-derived molecules. The first to show this was a study of suppressive effects of whole body extract of A. suum (Lima et al., 2002), which could be replicated with the purified single product, PAS-1 (Itami et al., 2005). Likewise, Acanthocheilonema viteae recombinant Av17 cystatin can suppress allergic airway pathology in a macrophage- and IL-10-dependent manner. Similar to administration of HES products in this model, this suppression was maintained whether Av17 was administered with sensitisation injections, or after them, prior to challenge (Schnoeller et al., 2008). Suppression of Th2 responses would be advantageous to most parasites, as this is the mode of response which most efficiently mediates their ejection. Future work should give valuable insights into the mechanisms of suppression of Th2 responses against both parasites and bystander antigens both at the level of Th2 induction (by administering parasite products with the OVA sensitisation), and established anti-parasite Th2 responses (by administering parasite products at OVA-airway challenge). A possibility that should be considered is whether helminth molecules induce a competing Th2 response, as many parasite products themselves induce potent Th2 responses in vivo (Balic et al., 2004; Dowling et al., 2011; Zaccone et al., 2011) and in the case of administration of NES products, an allergic-type response developed to the ES antigens themselves (Trujillo-Vargas et al., 2007). 6. Autoimmunity Most autoimmune diseases involve hyperreactivity of the Th1 and Th17 effector subsets. While it is not so obviously advantageous to the parasite to suppress these responses (as opposed to parasite-toxic Th2 responses), an indirect benefit may be to create a less inflammatory environment, e.g. in the intestinal tract, for parasite residence. Suppression of bystander Th1 and Th17 responses has been reported in a range of autoimmune diseases as well as in immunopathological contexts such as colitis. A commonly used model of autoimmunity is the type 1 diabetes-like disease which spontaneously arises in Non-Obese Diabetic (NOD) mice, which results in progressive destruction of insulin-producing islets in the pancreas (Anderson and Bluestone, 2005). Litomosoides sigmodontis adult worm antigen and S. mansoni SEA and soluble worm antigen preparation (SWAP) have each been shown to suppress autoimmune responses in NOD mice (Zaccone et al., 2003, 2009, 2010; Hubner et al., 2009). Suppression of diabetic pathology by SEA was associated with expansion of invariant Natural Killer T cells (iNKT cells, which are deficient in NOD mice), Tregs and alternatively activated macrophages (Zaccone et al., 2003, 2009, 2010). This may be a reflection of a physiological mechanism to minimise pathology in schistosome infection, as expansion of iNKT cells, Tregs and alternatively activated macrophages have all been found to be important in regulating the anti-schistosome immune response (Mallevaey et al., 2007; Wilson et al., 2007). Trichuris suis live infection has shown some efficacy in treating human multiple sclerosis (Fleming et al., 2011) and administration of products from T. suis or the related parasite, Trichinella spiralis, show suppression of pathology in the mouse model of multiple sclerosis, known as Experimental Autoimmune Encephalomyelitis (EAE) (Kuijk et al., 2012). Administration of SEA also suppresses EAE pathology, through skewing the immune responses from Th1/Th17 to Th2 (Zheng et al., 2008). As mentioned above, parasite products are capable of modulating DCs to induce Th2 responses, and suppress the inflammatory Th1-inducing phenotype. Intriguingly, it was recently shown that F. hepatica total extract is capable of skewing CpG-stimulated DCs to a tolerogenic phenotype which, when transferred to collagen-immunised mice, could suppress collagen-induced arthritis (Carranza et al., 2012). Most notably, ES-62 from the rodent filarial parasite, A. viteae, has shown efficacy in models of arthritis, as will be discussed by Rzepecka et al. (2012). 7. IBD and colitis IBD in humans include Crohn’s disease, which affects all parts of the gastrointestinal tract; and ulcerative colitis, which affects only the colon (Baumgart and Carding, 2007). Both of these diseases have autoimmune characteristics, but a role for intestinal barrier disruption and immune responses to commensal bacteria has also been proposed, especially in Crohn’s disease (Baumgart and Sandborn, 2012). These diseases are presently incurable and treatment consists of immune suppression and, in extreme cases, bowel resection. Another common immune-mediated disease of the intestine is coeliac disease, caused by immune responses both to oral gluten and to the host enzyme which digests gluten, tissue transglutaminase (Di Sabatino and Corazza, 2009). There are several mouse models of inflammatory IBD, which can be divided into those which depend on degradation of the intestinal epithelial barrier (such as Dextran Sulphate Sodium (DSS), or di- or tri-nitrobenzene sulphonic acid (DNBS or TNBS) colitis) (Wirtz et al., 2007) or those which depend on perturbation of the immune system leading to initiation of an inflammatory T cell response to commensals (such as the T cell transfer (Ostanin et al., 2009) or IL-10-deficient (Berg et al., 2002) models of colitis). It is worth noting that of these models, DSS colitis is wholly dependent on innate responses to commensal bacteria (it is ablated in germ-free mice), and is largely T cell-independent (similar progression of disease is seen in T cell-deficient mice) (Wirtz et al., 2007), while all other models are entirely dependent on T cell responses. In the T cell-dependent model of colitis engendered by TNBS exposure, whole worm extract of S. mansoni or Ancylostoma caninum ES products, when given at TNBS administration, can suppress colitic pathology (Ruyssers et al., 2009). Likewise, ES products of a related hookworm, Ancylostoma ceylanicum, suppress pathology in the DSS model (Cancado et al., 2011). In DNBS colitis, products of the tapeworm, Hymenolepis diminuta, suppress pathology (Johnston et al., 2010), and induce alternative activation of macrophages. Transfer of in vitro-derived alternatively activated macrophages to H.J. McSorley et al. / International Journal for Parasitology 43 (2013) 301–310 naïve recipients also suppressed colitis, thus providing a link between suppression of pathology and macrophage phenotype (Hunter et al., 2010). An interesting range of molecular species has been associated with suppression of IBD pathologies. For example, T. spiralis muscle-stage antigen extract, when administered submucosally in the rectum, can suppress DNBS colitis and this suppression was associated with an emergence of Th2 (IL-13) and regulatory (TGF-b) cytokine production in the colon (Motomura et al., 2009). The protective effect of T. spiralis antigens in colitis could be recapitulated with administration of recombinant TsP53, which induced IL-10 and TGF-b (Du et al., 2011). Likewise, SEA suppresses colitis and this activity can be replicated using the S. mansoni products Sm22.6, PIII and Sm29. Perhaps surprisingly IPSE, a known immunomodulatory and Th2-amplifying molecule within SEA, has no effect in this system, indicating that specific modulators target different inflammatory pathways in the host (Cardoso et al., 2010). Another defined molecule with anti-colitic activity is found in Toxascaris leonina, an intestinal parasite of dogs, which encodes the galectin-9 homologue, Tl-gal. Similar to that seen with TsP53 administration (Du et al., 2011), when the T. leonina galectin homologue was administered in the DSS colitis model, suppression of pathology was seen, together with induction of IL-10 and TGF-b (Kim et al., 2010). Galectins are widely expressed by helminth parasites and frequently found in the ES material (Hewitson et al., 2009), while in mammals there are many instances of galectins acting to suppress immunological reactions (Rabinovich et al., 2002). The broader role of galectins as parasite immunomodulators will be discussed in greater detail in the Section 8. In addition to galectins, the cystatin (cysteine protease inhibitors) family is also associated with helminth immunomodulation (Hartmann and Lucius, 2003; Gregory and Maizels, 2008). The filarial nematode, A. viteae, and the liver fluke, Clonorchis sinesis, both produce cystatins which suppress pathology in the DSS colitis model and induce IL-10-producing macrophages (Jang et al., 2011; Schnoeller et al., 2008). Therefore cystatins (present in many parasite secretions, including those of H. polygyrus (Hewitson et al., 2011b)) may be common parasite immunomodulators that have evolved in these evolutionarily very distinct lineages. Although the ability of H. polygyrus to suppress pathology in colitis through interactions with the innate and adaptive immune system has been well investigated (Elliott et al., 2004; Sutton et al., 2008; Blum et al., 2012), HES products have not to date been tested. This may be a rich seam for novel therapeutic agents in IBD. 8. Molecular characterisation of H. polygyrus ES material Motivated by the findings that adult parasite secretions contain both heat labile (TGF-b-mimic mediated generation of suppressive Treg cells) and heat stable (inhibition of allergic inflammation in vivo) immunomodulatory components, we have embarked on a proteomic and glycomic characterisation of adult HES. More than 350 proteins present in adult HES have been identified, many of which are shared with the secretions of the tissue-dwelling L4 (Hewitson et al., 2011b; our unpublished data). Proteomic studies have revealed that HES products are very extensively distinct from adult worm somatic extract, with preferential secretion of several families of proteins, in particular members of the venom-allergen-like (VAL) superfamily, apyrases, lysozymes, acetylcholinesterases, proteases and protease inhibitors (Hewitson et al., 2011b). Secretion of such proteins has been previously noted in other strongylid nematodes, including those of veterinary (Haemonchus contortus (Yatsuda et al., 2003); T. circumcincta (Nisbet et al., 2010)) and medical importance (hookworms; (Mulvenna 305 et al., 2009)), suggesting H. polygyrus is a useful laboratory model for these important diseases. The most striking feature of adult HES products are the large number (25) of VAL proteins, containing a characteristic cysteine-rich motif also found in sperm coat protein (SCP, pfam domain PF00188; http://www.ebi.ac.uk/goldman-srv/pandit/pandit.cgi?action=browse&fam=PF00188; http://pfam.sanger.ac.uk/ family/PF00188). Originally identified as dominant secretions of larval hookworms, termed Ancylostoma secreted proteins, or ASPs (Hawdon et al., 1996), it is now clear that adult worms also secrete large numbers and amounts of these proteins. Proteins of this family have been previously trialled in humans as vaccine candidates, although this has proved problematic owing to their allergenic nature (Diemert et al., 2012). Because the secreted VAL proteins of H. polygyrus and other helminths (Mulvenna et al., 2009; Cantacessi and Gasser, 2012) have a high degree of sequence diversity, doubt has been raised as to whether they share an evolutionarily conserved function such as immunomodulation, or whether the SCP domain simply represents a versatile protein module with which distinct functions can be built (Cantacessi and Gasser, 2012). Nevertheless, some immunomodulatory functions have been ascribed to VAL proteins including neutrophil chemoattraction (Asojo et al., 2005; Bower et al., 2008). Perhaps surprisingly, VAL proteins have also been shown to have Th1 adjuvant-promoting abilities in vivo (He et al., 2009) through direct interaction with antigen presenting cells and TLR triggering. VAL proteins are characterised by the presence of one or two SCP domains, and both single- and double-domain VALs are present in HES products. Analysis of antibody binding has revealed that both classes of VAL protein are the immundominant target of IgG1 antibodies in primary and secondary H. polygyrus infection (Hewitson et al., 2011a), an antibody isotype previously shown to be protective in this infection (McCoy et al., 2008). Additionally, the two SCP domains of the double domain VAL proteins are connected by a 20–40 amino acid linker region rich in serine and threonine residues, which are decorated with a common O-linked sugar (named ‘‘glycan A’’ (Hewitson et al., 2011a)), which represents the dominant IgM target in infection. Amongst other candidate immunomodulators, HES products contain a cystatin, as mentioned previously. As cystatins produced by A. viteae and C. sinesis are protective in allergic airway pathology and colitis (Schnoeller et al., 2008; Jang et al., 2011), this target may warrant more study. HES products also contain three members of another protease inhibitor family, the serpins. Serpins are a family of proteins which suppress serine proteases such as neutrophil elastase and cathepsin G, and are produced by a range of parasites (Zang and Maizels, 2001; Molehin et al., 2012). Elastase and cathepsin G are responsible for activation of the ‘alarmin’ cytokine, IL-33 (Lefrancais et al., 2012). IL-33 induces innate lymphoid cells, alternatively activated macrophages and eosinophilia during the initialisation of innate type 2 responses (Koyasu and Moro, 2011). Thus serpins may be important in suppressing the very earliest events in Th2 induction during parasitic infections. Another potential immunomodulatory family in HES products are the apyrases, four of which were detected. Apyrases convert immunostimulatory ATP to more tolerogenic AMP and adenosine, and whilst extracellular ATP can promote lung and gut inflammation, apyrases are able to prevent this (Idzko et al., 2007). In the intestine, ATP is required for the generation of pro-inflammatory Th17 cells (Atarashi et al., 2008) and promotes the conversion of Treg cells into effector Th17 cells (Schenk et al., 2011), both of which processes seem likely to be limited by apyrase enzymes. Functional apyrases have also been identified as potential immunomodulators from other parasites, including T. circumcincta (Nisbet et al., 2011). 306 H.J. McSorley et al. / International Journal for Parasitology 43 (2013) 301–310 Multiple families of carbohydrate-binding proteins are found in HES products: two chitinase/chitin-binding domain proteins, five galectins and three C-type lectins. Particularly prominent are the chitinase proteins, which are of interest as immunomodulators as chitin induces Th2 responses and high levels of host chitinases are produced during active Th2 responses such as asthma (Sutherland et al., 2009). Thus, chitinases in HES products could result in lower levels of parasite-derived chitin and a reduced Th2 response. Galectins are multifunctional immune mediators in the mammalian immune system, however a feature common to mammalian galectins 1, 2, 3, 4, 8 and 9 is the ability to cause apoptosis in activated T cells, while mammalian galectins 1 and 9 are both expressed by mouse Tregs and selectively cause apoptosis of Th1 (but not Th2) cells (Liu et al., 2012). As mentioned previously, a galectin-9 homologue from T. leonina protects against colitis (Kim et al., 2010). Thus, H. polygyrus and other parasites may produce galectins to inhibit activated T cell (especially Th1) responses. HES products also contain two fatty acid/retinol binding proteins. As the downstream metabolite of retinol, retinoic acid, is important in the intestine for inducing Tregs and suppressing Th17 differentiation, it is tempting to speculate that these could potentiate Treg induction (Elias et al., 2008). More broadly, retinoic acid deficiency results in a generalised impairment of immune responsiveness (Hall et al., 2011) and hence dampening of immunity could result if, as reported (Comley and Jaffe, 1983), helminths are able to sequester this molecule. Retinol-binding proteins are found in many parasitic helminths including Taenia solium, Ascaris spp., Toxocara canis and filarial parasites including B. malayi and Loa loa (Esteves and Ehrlich, 2006; Kim et al., 2012b). Fatty-acid binding proteins may well function in parasite acquisition of host molecules, or to deliver them to target cell types, but their role in modulation of the host immune response remains to be investigated. Eight lysozymes have been identified in HES products. Lysozymes degrade peptidoglycan in bacterial cells walls (especially Gram positive bacterial cells walls), and as H. polygyrus infection is known to change the commensal balance in the intestine (Walk et al., 2010), these could be a potential mediator. Growing interest has developed in how commensals affect immune responses (Molloy et al., 2012), therefore this could be a mechanism by which the parasite skews immune responses in the intestine. Evidence that this is advantageous to the parasite comes from recent data showing that the higher the levels of Lactobacillus spp. in the intestine, the greater the adult worm number (Maizels et al., 2012). A new insight into the biology of H. polygyrus infections is also afforded by analysis of the ES products from immature L4s developing in the intestinal tissue, beneath the muscular layer. Proteomic characterisation identifies a substantial overlap between the secretomes of adult and L4 parasites, although there is a relative expansion of VAL family members in the lumina-dwelling adult repertoire (Hewitson et al., unpublished data). In contrast, other gene families are greatly expanded in the tissue-dwelling L4. Among these are proteins containing a 36-amino acid motif with six cysteines in a distinct configuration (SXC), first noted in the ES of the nematode T. canis (Gems et al., 1995) and independently in a potassium-blocking toxin of a marine anemone, (Tudor et al., 1996). Interestingly, the sea anemone toxin can block activation in mammalian T cells, and itself is being tested as a potential therapeutic agent for autoimmune disease (Chi et al., 2012). Thus, the ability of helminth SXC-containing proteins to act in a similar manner urgently needs to be assessed. Finally, HES products contain large numbers of previously uncharacterised proteins, termed novel secreted proteins (NSPs), many of which cluster into distinct NSP families. Although the function (immunomodulatory or otherwise) of these proteins remains unknown, their presence in HES products (and often not in the parasite somatic extract) implies some interaction with the host. Clearly there are multiple potential immunomodulatory protein families in HES products (Table 1), however many proteins in HES products are also highly glycosylated and the immunosuppressive role of individual HES-derived glycans has not yet been addressed. A role for glycans in HES product immunosuppression is implied by the heat-stability of the suppressive factor in a mouse model of asthma (McSorley et al., 2012). On-going glycomic characterisation of purified VAL proteins has revealed the presence of several short O-glycans, a subset of which are likely to be the ‘‘glycan A’’ antigen (J Hewitson, unpublished observations). Although an immunomodulatory role for this sugar has not yet been described, it is detectable in the serum of infected mice, indicating its potential (and that of other parasite secretions) to traffic to, and influence, immune cells in distal sites (Herbst et al., 2012). Table 1 Immunomodulatory protein families contained in Heligmosomoides polygyrus Excretory/Secretory products. Protein family Immunological effects Reference Apyrase Degrade inflammatory ATP Suppress pathology in models of asthma ATP induces Th17 cells in the gut Chitin promotes Th2 Chitinase reduces Th2? Inhibit antigen processing Suppress pathology in models of asthma and colitis Apoptosis of activated T cells, especially Th1 cells Degrade bacterial cell walls Change commensal balance? Retinol induces Tregs, suppresses Th17 Reduced immune responsiveness in retinol deficiency Inhibit serine proteases – e.g. neutrophil elastase/cathepsin G Inhibit IL-33 activation? Allergenic Vaccine candidates Neutrophil chemoattraction Th1-promoting Suppress T and B cell proliferation Induce Foxp3+ Tregs Suppress APC maturation/prevents TLR signaling Idzko et al. (2007) Chitinase/chitin-binding Cystatin Galectin Lysozyme Retinol-binding Serpin VAL/ASP/SCP TGF-b mimic Atarashi et al. (2008) Sutherland et al. (2009) and Da Silva et al. (2010) Manoury et al. (2001) Schnoeller et al. (2008) and Jang et al. (2011) Kim et al. (2010), Liu et al. (2012) Dommett et al. (2005) Walk et al. (2010) Esteves and Ehrlich (2006), Elias et al. (2008) and Kim et al. (2012b) Zang et al. (1999) and Molehin et al. (2012) Lefrancais et al. (2012) Diemert et al. (2012) Asojo et al. (2005) Bower et al. (2008) He et al. (2009) Grainger et al. (2010) Tregs, regulatory T cells; VAL, venom-allergen-like; ASP, Ancylostoma secreted protein; SCP, sperm coat protein; APC, antigen presenting cell; TLR, toll-like receptor. H.J. McSorley et al. / International Journal for Parasitology 43 (2013) 301–310 9. Helminth therapies: towards clinical application The wealth and diversity of helminth molecules with potential for the therapy of immune dysfunctions in humans present an enormous resource for future applications, matched only by the scale of challenges that must be met to reach a clinically-approved therapy. At this early stage, most modulators under study are parasite proteins, which may prove too immunogenic in the human for use without modification. In addition, many are derived from animal model parasites, and the efficacy of proteins optimally adapted to animal species requires verification in the human setting. For both reasons, it is likely that pathways of immunomodulation need to be carefully mapped, so that parasite effects can be reproduced by small molecules or humanised reagents containing the minimal effective parasite-encoded motifs required to interact with key host molecules. In this context, trials under way with live helminth therapies are both encouraging and informative. The success, even on a small scale, of live helminth treatments would validate the ‘‘Hygiene Hypothesis’’ as the rationale for using helminth molecules to alleviate immunopathologies, and a careful immunological analysis of recipients of helminth therapy will provide important pointers to the immunosuppressive pathways that may be activated in these patients. It will be essential to consider each species (e.g. T. suis versus N. americanus) as very different systems, as the variety of molecules and mechanisms discussed above argues strongly that each parasite is exquisitely adapted to a precise and probably unique series of immunological interactions. By breaking down the complexity of these interactions into defined, targeted effects, future molecular therapies based on helminth-derived modulators should achieve the goal of providing new pharmacological agents which can be applied at appropriate doses and intervals to control specific immunopathologies in human patients. 10. Conclusion Parasitic helminths produce a myriad of immunomodulatory molecules to suppress anti-parasite and immunopathological responses at multiple levels, from the very early initiating events in innate immunity to the final effector mechanisms in established adaptive responses. Interestingly, helminth products can block both Th1/Th17-mediated inflammation and Th2-dependent pathologies, giving them the potential to treat the full range of human immunological disorders. Moreover, helminth infections are themselves chronic diseases, sharing a time-scale and dynamic with many of the autoimmune and allergic conditions that we seek to treat. If parasites have evolved to also manipulate the immune response in a state of chronic stimulation, the molecules involved may be particularly apposite for human therapy. Such prospects remain to be fully tested, but the weight of evidence in both humans and animal models gives us grounds for real optimism towards new molecular therapies from helminths. Acknowledgements The authors thank the Wellcome Trust, UK and the American Asthma Foundation for funding. References Abdulla, M.H., Lim, K.C., McKerrow, J.H., Caffrey, C.R., 2011. Proteomic identification of IPSE/alpha-1 as a major hepatotoxin secreted by Schistosoma mansoni eggs. PLoS Negl. Trop. Dis. 5, e1368. Allen, J.E., Maizels, R.M., 2011. Diversity and dialogue in immunity to helminths. Nat. Rev. Immunol. 11, 375–388. Anderson, M.S., Bluestone, J.A., 2005. The NOD mouse: a model of immune dysregulation. Annu. Rev. Immunol. 23, 447–485. 307 Aranzamendi, C., Fransen, F., Langelaar, M., Franssen, F., van der Ley, P., van Putten, J.P., Rutten, V., Pinelli, E., 2012. Trichinella spiralis-secreted products modulate DC functionality and expand regulatory T cells in vitro. Parasite Immunol. 34, 210–223. Asojo, O.A., Goud, G., Dhar, K., Loukas, A., Zhan, B., Deumic, V., Liu, S., Borgstahl, G.E., Hotez, P.J., 2005. X-ray structure of Na-ASP-2, a pathogenesis-related-1 protein from the nematode parasite, Necator americanus, and a vaccine antigen for human hookworm infection. J. Mol. Biol. 346, 801–814. Atarashi, K., Nishimura, J., Shima, T., Umesaki, Y., Yamamoto, M., Onoue, M., Yagita, H., Ishii, N., Evans, R., Honda, K., Takeda, K., 2008. ATP drives lamina propria T(H)17 cell differentiation. Nature 455, 808–812. Atochina, O., Da’dara, A.A., Walker, M., Harn, D.A., 2008. The immunomodulatory glycan LNFPIII initiates alternative activation of murine macrophages in vivo. Immunology 125, 111–121. Bager, P., Arnved, J., Ronborg, S., Wohlfahrt, J., Poulsen, L.K., Westergaard, T., Petersen, H.W., Kristensen, B., Thamsborg, S., Roepstorff, A., Kapel, C., Melbye, M., 2010. Trichuris suis ova therapy for allergic rhinitis: a randomized, doubleblind, placebo-controlled clinical trial. J. Allergy Clin. Immunol. 125 (123–130), e121–123. Bai, X., Wu, X., Wang, X., Guan, Z., Gao, F., Yu, J., Yu, L., Tang, B., Liu, X., Song, Y., Radu, B., Boireau, P., Wang, F., Liu, M., 2012. Regulation of cytokine expression in murine macrophages stimulated by excretory/secretory products from Trichinella spiralis in vitro. Mol. Cell. Biochem. 360, 79–88. Balic, A., Harcus, Y., Holland, M.J., Maizels, R.M., 2004. Selective maturation of dendritic cells by Nippostrongylus brasiliensis-secreted proteins drives Th2 immune responses. Eur. J. Immunol. 34, 3047–3059. Bates, J.H., Rincon, M., Irvin, C.G., 2009. Animal models of asthma. Am. J. Physiol. Lung Cell. Mol. Physiol. 297, L401–410. Baumgart, D.C., Carding, S.R., 2007. Inflammatory bowel disease: cause and immunobiology. Lancet 369, 1627–1640. Baumgart, D.C., Sandborn, W.J., 2012. Crohn’s disease. Lancet 380, 1590–1603. Benzel, F., Erdur, H., Kohler, S., Frentsch, M., Thiel, A., Harms, L., Wandinger, K.P., Rosche, B., 2012. Immune monitoring of Trichuris suis egg therapy in multiple sclerosis patients. J. Helminthol. 86, 339–347. Berg, D.J., Zhang, J., Weinstock, J.V., Ismail, H.F., Earle, K.A., Alila, H., Pamukcu, R., Moore, S., Lynch, R.G., 2002. Rapid development of colitis in NSAID-treated IL10-deficient mice. Gastroenterology 123, 1527–1542. Bhargava, P., Li, C., Stanya, K.J., Jacobi, D., Dai, L., Liu, S., Gangl, M.R., Harn, D.A., Lee, C.H., 2012. Immunomodulatory glycan LNFPIII alleviates hepatosteatosis and insulin resistance through direct and indirect control of metabolic pathways. Nat. Med. 18, 1665–1672. Blount, D., Hooi, D., Feary, J., Venn, A., Telford, G., Brown, A., Britton, J., Pritchard, D., 2009. Immunologic profiles of persons recruited for a randomized, placebocontrolled clinical trial of hookworm infection. Am. J. Trop. Med. Hyg. 81, 911– 916. Blum, A.M., Hang, L., Setiawan, T., Urban Jr., J.P., Stoyanoff, K.M., Leung, J., Weinstock, J.V., 2012. Heligmosomoides polygyrus bakeri induces tolerogenic dendritic cells that block colitis and prevent antigen-specific gut T cell responses. J. Immunol. 189, 2512–2520. Bower, M.A., Constant, S.L., Mendez, S., 2008. Necator americanus: the Na-ASP-2 protein secreted by the infective larvae induces neutrophil recruitment in vivo and in vitro. Exp. Parasitol. 118, 569–575. Broadhurst, M.J., Leung, J.M., Kashyap, V., McCune, J.M., Mahadevan, U., McKerrow, J.H., Loke, P., 2010. IL-22+ CD4+ T cells are associated with therapeutic Trichuris trichiura infection in an ulcerative colitis patient. Sci. Transl. Med. 2, 60ra88. Cancado, G.G., Fiuza, J.A., de Paiva, N.C., Lemos Lde, C., Ricci, N.D., GazzinelliGuimaraes, P.H., Martins, V.G., Bartholomeu, D.C., Negrao-Correa, D.A., Carneiro, C.M., Fujiwara, R.T., 2011. Hookworm products ameliorate dextran sodium sulfate-induced colitis in BALB/c mice. Inflamm. Bowel Dis. 17, 2275–2286. Cantacessi, C., Gasser, R.B., 2012. SCP/TAPS proteins in helminths – where to from now? Mol. Cell. Probes 26, 54–59. Cardoso, L.S., Oliveira, S.C., Goes, A.M., Oliveira, R.R., Pacifico, L.G., Marinho, F.V., Fonseca, C.T., Cardoso, F.C., Carvalho, E.M., Araujo, M.I., 2010. Schistosoma mansoni antigens modulate the allergic response in a murine model of ovalbumin-induced airway inflammation. Clin. Exp. Immunol. 160, 266–274. Carneiro-Santos, P., Martins-Filho, O., Alves-Oliveira, L.F., Silveira, A.M., Coura-Filho, P., Viana, I.R., Wilson, R.A., Correa-Oliveira, R., 2000. Apoptosis: a mechanism of immunoregulation during human Schistosomiasis mansoni. Parasite Immunol. 22, 267–277. Carranza, F., Falcon, C.R., Nunez, N., Knubel, C., Correa, S.G., Bianco, I., Maccioni, M., Fretes, R., Triquell, M.F., Motran, C.C., Cervi, L., 2012. Helminth antigens enable CpG-activated dendritic cells to inhibit the symptoms of collagen-induced arthritis through Foxp3+ regulatory T cells. PLoS One 7, e40356. Chi, V., Pennington, M.W., Norton, R.S., Tarcha, E.J., Londono, L.M., Sims-Fahey, B., Upadhyay, S.K., Lakey, J.T., Iadonato, S., Wulff, H., Beeton, C., Chandy, K.G., 2012. Development of a sea anemone toxin as an immunomodulator for therapy of autoimmune diseases. Toxicon 59, 529–546. Comley, J.C., Jaffe, J.J., 1983. The conversion of exogenous retinol and related compounds into retinyl phosphate mannose by adult Brugia pahangi in vitro. Biochem. J. 214, 367–376. Correale, J., Farez, M., 2007. Association between parasite infection and immune responses in multiple sclerosis. Ann Neurol. 61, 97–108. Correale, J., Farez, M., Razzitte, G., 2008. Helminth infections associated with multiple sclerosis induce regulatory B cells. Ann. Neurol. 64, 187–199. Correale, J., Farez, M.F., 2011. The impact of parasite infections on the course of multiple sclerosis. J. Neuroimmunol. 233, 6–11. 308 H.J. McSorley et al. / International Journal for Parasitology 43 (2013) 301–310 Croese, J., O’Neil, J., Masson, J., Cooke, S., Melrose, W., Pritchard, D., Speare, R., 2006. A proof of concept study establishing Necator americanus in Crohn’s patients and reservoir donors. Gut 55, 136–137. Culley, F.J., Brown, A., Conroy, D.M., Sabroe, I., Pritchard, D.I., Williams, T.J., 2000. Eotaxin is specifically cleaved by hookworm metalloproteases preventing its action in vitro and in vivo. J. Immunol. 165, 6447–6453. Da Silva, C.A., Pochard, P., Lee, C.G., Elias, J.A., 2010. Chitin particles are multifaceted immune adjuvants. Am. J. Respir. Crit. Care Med. 182, 1482–1491. Danilowicz-Luebert, E., O’Regan, N.L., Steinfelder, S., Hartmann, S., 2011. Modulation of specific and allergy-related immune responses by helminths. J. Biomed. Biotechnol. 2011, 821578. Daveson, A.J., Jones, D.M., Gaze, S., McSorley, H., Clouston, A., Pascoe, A., Cooke, S., Speare, R., Macdonald, G.A., Anderson, R., McCarthy, J.S., Loukas, A., Croese, J., 2011. Effect of hookworm infection on wheat challenge in celiac disease – a randomised double-blinded placebo controlled trial. PLoS One 6, e17366. Di Sabatino, A., Corazza, G.R., 2009. Coeliac disease. Lancet 373, 1480–1493. Diemert, D.J., Pinto, A.G., Freire, J., Jariwala, A., Santiago, H., Hamilton, R.G., Periago, M.V., Loukas, A., Tribolet, L., Mulvenna, J., Correa-Oliveira, R., Hotez, P.J., Bethony, J.M., 2012. Generalized urticaria induced by the Na-ASP-2 hookworm vaccine: implications for the development of vaccines against helminths. J. Allergy Clin. Immunol. 130 (169–176), e166. Dommett, R., Zilbauer, M., George, J.T., Bajaj-Elliott, M., 2005. Innate immune defence in the human gastrointestinal tract. Mol. Immunol. 42, 903–912. Donnelly, S., Stack, C.M., O’Neill, S.M., Sayed, A.A., Williams, D.L., Dalton, J.P., 2008. Helminth 2-Cys peroxiredoxin drives Th2 responses through a mechanism involving alternatively activated macrophages. FASEB J. 22, 4022–4032. Dowling, D.J., Noone, C.M., Adams, P.N., Vukman, K.V., Molloy, S.F., Forde, J., Asaolu, S., O’Neill, S.M., 2011. Ascaris lumbricoides pseudocoelomic body fluid induces a partially activated dendritic cell phenotype with Th2 promoting ability in vivo. Int. J. Parasitol. 41, 255–261. Du, L., Tang, H., Ma, Z., Xu, J., Gao, W., Chen, J., Gan, W., Zhang, Z., Yu, X., Zhou, X., Hu, X., 2011. The protective effect of the recombinant 53-kDa protein of Trichinella spiralis on experimental colitis in mice. Dig. Dis. Sci. 56, 2810–2817. Elias, K.M., Laurence, A., Davidson, T.S., Stephens, G., Kanno, Y., Shevach, E.M., O’Shea, J.J., 2008. Retinoic acid inhibits Th17 polarization and enhances FoxP3 expression through a Stat-3/Stat-5 independent signaling pathway. Blood 111, 1013–1020. Elliott, D.E., Setiawan, T., Metwali, A., Blum, A., Urban Jr., J.F., Weinstock, J.V., 2004. Heligmosomoides polygyrus inhibits established colitis in IL-10-deficient mice. Eur. J. Immunol. 34, 2690–2698. Elliott, D.E., Weinstock, J.V., 2009. Helminthic therapy: using worms to treat immune-mediated disease. Adv. Exp. Med. Biol. 666, 157–166. Elliott, D.E., Weinstock, J.V., 2012. Helminth-host immunological interactions: prevention and control of immune-mediated diseases. Ann. N.Y. Acad. Sci. 1247, 83–96. Esteves, A., Ehrlich, R., 2006. Invertebrate intracellular fatty acid binding proteins. Comp. Biochem. Physiol. C: Toxicol. Pharmacol. 142, 262–274. Everts, B., Hussaarts, L., Driessen, N.N., Meevissen, M.H., Schramm, G., van der Ham, A.J., van der Hoeven, B., Scholzen, T., Burgdorf, S., Mohrs, M., Pearce, E.J., Hokke, C.H., Haas, H., Smits, H.H., Yazdanbakhsh, M., 2012. Schistosome-derived omega-1 drives Th2 polarization by suppressing protein synthesis following internalization by the mannose receptor. J. Exp. Med. 209, 1753–1767. Everts, B., Perona-Wright, G., Smits, H.H., Hokke, C.H., van der Ham, A.J., Fitzsimmons, C.M., Doenhoff, M.J., van der Bosch, J., Mohrs, K., Haas, H., Mohrs, M., Yazdanbakhsh, M., Schramm, G., 2009. Omega-1, a glycoprotein secreted by Schistosoma mansoni eggs, drives Th2 responses. J. Exp. Med. 206, 1673–1680. Falcon, C., Carranza, F., Martinez, F.F., Knubel, C.P., Masih, D.T., Motran, C.C., Cervi, L., 2010. Excretory-secretory products (ESP) from Fasciola hepatica induce tolerogenic properties in myeloid dendritic cells. Vet. Immunol. Immunopathol. 137, 36–46. Fallon, P.G., Richardson, E.J., McKenzie, G.J., McKenzie, A.N., 2000. Schistosome infection of transgenic mice defines distinct and contrasting pathogenic roles for IL-4 and IL-13: IL-13 is a profibrotic agent. J. Immunol. 164, 2585–2591. Feary, J., Britton, J., Leonardi-Bee, J., 2011. Atopy and current intestinal parasite infection: a systematic review and meta-analysis. Allergy 66, 569–578. Feary, J., Venn, A., Brown, A., Hooi, D., Falcone, F.H., Mortimer, K., Pritchard, D.I., Britton, J., 2009. Safety of hookworm infection in individuals with measurable airway responsiveness: a randomized placebo-controlled feasibility study. Clin. Exp. Allergy 39, 1060–1068. Fleming, J.O., 2011. Helminths and multiple sclerosis: will old friends give us new treatments for MS? J. Neuroimmunol. 233, 3–5. Fleming, J.O., Isaak, A., Lee, J.E., Luzzio, C.C., Carrithers, M.D., Cook, T.D., Field, A.S., Boland, J., Fabry, Z., 2011. Probiotic helminth administration in relapsingremitting multiple sclerosis: a phase 1 study. Mult. Scler. 17, 743–754. Gems, D., Ferguson, C.J., Robertson, B.D., Nieves, R., Page, A.P., Blaxter, M.L., Maizels, R.M., 1995. An abundant, trans-spliced mRNA from Toxocara canis infective larvae encodes a 26-kDa protein with homology to phosphatidylethanolaminebinding proteins. J. Biol. Chem. 270, 18517–18522. Gordon, S., 2003. Alternative activation of macrophages. Nat. Rev. Immunol. 3, 23– 35. Grainger, J.R., Smith, K.A., Hewitson, J.P., McSorley, H.J., Harcus, Y., Filbey, K.J., Finney, C.A., Greenwood, E.J., Knox, D.P., Wilson, M.S., Belkaid, Y., Rudensky, A.Y., Maizels, R.M., 2010. Helminth secretions induce de novo T cell Foxp3 expression and regulatory function through the TGF-beta pathway. J. Exp. Med. 207, 2331–2341. Gregory, W.F., Maizels, R.M., 2008. Cystatins from filarial parasites: evolution, adaptation and function in the host-parasite relationship. Int. J. Biochem. Cell Biol. 40, 1389–1398. Gruden-Movsesijan, A., Ilic, N., Colic, M., Majstorovic, I., Vasilev, S., Radovic, I., Sofronic-Milosavljevic, L., 2011. The impact of Trichinella spiralis excretorysecretory products on dendritic cells. Comp. Immunol. Microbiol. Infect. Dis. 34, 429–439. Guasconi, L., Serradell, M.C., Masih, D.T., 2012. Fasciola hepatica products induce apoptosis of peritoneal macrophages. Vet. Immunol. Immunopathol. 148, 359– 363. Hall, J.A., Grainger, J.R., Spencer, S.P., Belkaid, Y., 2011. The role of retinoic acid in tolerance and immunity. Immunity 35, 13–22. Hamilton, C.M., Dowling, D.J., Loscher, C.E., Morphew, R.M., Brophy, P.M., O’Neill, S.M., 2009. The Fasciola hepatica tegumental antigen suppresses dendritic cell maturation and function. Infect. Immun. 77, 2488–2498. Harn, D.A., McDonald, J., Atochina, O., Da’dara, A.A., 2009. Modulation of host immune responses by helminth glycans. Immunol. Rev. 230, 247–257. Harnett, W., Harnett, M.M., 2010. Helminth-derived immunomodulators: can understanding the worm produce the pill? Nat. Rev. Immunol. 10, 278–284. Hartmann, S., Lucius, R., 2003. Modulation of host immune responses by nematode cystatins. Int. J. Parasitol. 33, 1291–1302. Hawdon, J.M., Jones, B.F., Hoffman, D.R., Hotez, P.J., 1996. Cloning and characterization of Ancylostoma-secreted protein. A novel protein associated with the transition to parasitism by infective hookworm larvae. J. Biol. Chem. 271, 6672–6678. He, Y., Barker, S.J., MacDonald, A.J., Yu, Y., Cao, L., Li, J., Parhar, R., Heck, S., Hartmann, S., Golenbock, D.T., Jiang, S., Libri, N.A., Semper, A.E., Rosenberg, W.M., Lustigman, S., 2009. Recombinant Ov-ASP-1, a Th1-biased protein adjuvant derived from the helminth Onchocerca volvulus, can directly bind and activate antigen-presenting cells. J. Immunol. 182, 4005–4016. Herbst, T., Esser, J., Prati, M., Kulagin, M., Stettler, R., Zaiss, M.M., Hewitson, J.P., Merky, P., Verbeek, J.S., Bourquin, C., Camberis, M., Prout, M., Maizels, R.M., Le Gros, G., Harris, N.L., 2012. Antibodies and IL-3 support helminth-induced basophil expansion. Proc. Natl. Acad. Sci. USA 109, 14954–14959. Hewitson, J.P., Filbey, K.J., Grainger, J.R., Dowle, A.A., Pearson, M., Murray, J., Harcus, Y., Maizels, R.M., 2011a. Heligmosomoides polygyrus elicits a dominant nonprotective antibody response directed against restricted glycan and peptide epitopes. J. Immunol. 187, 4764–4777. Hewitson, J.P., Grainger, J.R., Maizels, R.M., 2009. Helminth immunoregulation: the role of parasite secreted proteins in modulating host immunity. Mol. Biochem. Parasitol. 167, 1–11. Hewitson, J.P., Harcus, Y., Murray, J., van Agtmaal, M., Filbey, K.J., Grainger, J.R., Bridgett, S., Blaxter, M.L., Ashton, P.D., Ashford, D.A., Curwen, R.S., Wilson, R.A., Dowle, A.A., Maizels, R.M., 2011b. Proteomic analysis of secretory products from the model gastrointestinal nematode Heligmosomoides polygyrus reveals dominance of venom allergen-like (VAL) proteins. J. Proteomics 74, 1573–1594. Hillwig, M.S., Rizhsky, L., Wang, Y., Umanskaya, A., Essner, J.J., MacIntosh, G.C., 2009. Zebrafish RNase T2 genes and the evolution of secretory ribonucleases in animals. BMC Evol. Biol. 9, 170. Holland, M.J., Harcus, Y.M., Balic, A., Maizels, R.M., 2005. Th2 induction by Nippostrongylus secreted antigens in mice deficient in B cells, eosinophils or MHC Class I-related receptors. Immunol. Lett. 96, 93–101. Holland, M.J., Harcus, Y.M., Riches, P.L., Maizels, R.M., 2000. Proteins secreted by the parasitic nematode Nippostrongylus brasiliensis act as adjuvants for Th2 responses. Eur. J. Immunol. 30, 1977–1987. Hubner, M.P., Stocker, J.T., Mitre, E., 2009. Inhibition of type 1 diabetes in filariainfected non-obese diabetic mice is associated with a T helper type 2 shift and induction of FoxP3+ regulatory T cells. Immunology 127, 512–522. Hunter, M.M., Wang, A., Parhar, K.S., Johnston, M.J., Van Rooijen, N., Beck, P.L., McKay, D.M., 2010. In vitro-derived alternatively activated macrophages reduce colonic inflammation in mice. Gastroenterology 138, 1395–1405. Idzko, M., Hammad, H., van Nimwegen, M., Kool, M., Willart, M.A., Muskens, F., Hoogsteden, H.C., Luttmann, W., Ferrari, D., Di Virgilio, F., Virchow Jr., J.C., Lambrecht, B.N., 2007. Extracellular ATP triggers and maintains asthmatic airway inflammation by activating dendritic cells. Nat. Med. 13, 913–919. Itami, D.M., Oshiro, T.M., Araujo, C.A., Perini, A., Martins, M.A., Macedo, M.S., Macedo-Soares, M.F., 2005. Modulation of murine experimental asthma by Ascaris suum components. Clin. Exp. Allergy 35, 873–879. Jang, S.W., Cho, M.K., Park, M.K., Kang, S.A., Na, B.K., Ahn, S.C., Kim, D.H., Yu, H.S., 2011. Parasitic helminth cystatin inhibits DSS-induced intestinal inflammation via IL-10(+)F4/80(+) macrophage recruitment. Korean J. Parasitol. 49, 245–254. Jankovic, D., Kullberg, M.C., Caspar, P., Sher, A., 2004. Parasite-induced Th2 polarization is associated with down-regulated dendritic cell responsiveness to Th1 stimuli and a transient delay in T lymphocyte cycling. J. Immunol. 173, 2419–2427. Johnston, M.J., Wang, A., Catarino, M.E., Ball, L., Phan, V.C., MacDonald, J.A., McKay, D.M., 2010. Extracts of the rat tapeworm, Hymenolepis diminuta, suppress macrophage activation in vitro and alleviate chemically induced colitis in mice. Infect. Immun. 78, 1364–1375. Jouvin, M.H., Kinet, J.P., 2012. Trichuris suis ova: testing a helminth-based therapy as an extension of the hygiene hypothesis. J. Allergy Clin. Immunol. 130, 3–10. Kaur, I., Schramm, G., Everts, B., Scholzen, T., Kindle, K.B., Beetz, C., Montiel-Duarte, C., Blindow, S., Jones, A.T., Haas, H., Stolnik, S., Heery, D.M., Falcone, F.H., 2011. Interleukin-4-inducing principle from Schistosoma mansoni eggs contains a functional C-terminal nuclear localization signal necessary for nuclear H.J. McSorley et al. / International Journal for Parasitology 43 (2013) 301–310 translocation in mammalian cells but not for its uptake. Infect. Immun. 79, 1779–1788. Kim, H.R., Lee, S.M., Won, J.W., Lim, W., Moon, B.I., Yang, H.J., Seoh, J.Y., 2012a. Functional changes in regulatory T cells during an experimental infection with sparganum (plerocercoid of Spirometra mansoni). Immunology 138, 57–67. Kim, J.Y., Cho, M.K., Choi, S.H., Lee, K.H., Ahn, S.C., Kim, D.H., Yu, H.S., 2010. Inhibition of dextran sulfate sodium (DSS)-induced intestinal inflammation via enhanced IL-10 and TGF-beta production by galectin-9 homologues isolated from intestinal parasites. Mol. Biochem. Parasitol. 174, 53–61. Kim, S.H., Bae, Y.A., Yang, H.J., Shin, J.H., Diaz-Camacho, S.P., Nawa, Y., Kang, I., Kong, Y., 2012b. Structural and binding properties of two paralogous fatty acid binding proteins of Taenia solium metacestode. PLoS Negl. Trop. Dis. 6, e1868. Koyasu, S., Moro, K., 2011. Innate Th2-type immune responses and the natural helper cell, a newly identified lymphocyte population. Curr. Opin. Allergy Clin. Immunol. 11, 109–114. Kuijk, L.M., Klaver, E.J., Kooij, G., van der Pol, S.M., Heijnen, P., Bruijns, S.C., Kringel, H., Pinelli, E., Kraal, G., de Vries, H.E., Dijkstra, C.D., Bouma, G., van Die, I., 2012. Soluble helminth products suppress clinical signs in murine experimental autoimmune encephalomyelitis and differentially modulate human dendritic cell activation. Mol. Immunol. 51, 210–218. Larson, D., Hubner, M.P., Torrero, M.N., Morris, C.P., Brankin, A., Swierczewski, B.E., Davies, S.J., Vonakis, B.M., Mitre, E., 2012. Chronic helminth infection reduces basophil responsiveness in an IL-10-dependent manner. J. Immunol. 188, 4188– 4199. Lee, K.H., Park, H.K., Jeong, H.J., Park, S.K., Lee, S.J., Choi, S.H., Cho, M.K., Ock, M.S., Hong, Y.C., Yu, H.S., 2008. Immunization of proteins from Toxascaris leonina adult worm inhibits allergic specific Th2 response. Vet. Parasitol. 156, 216–225. Lefrancais, E., Roga, S., Gautier, V., Gonzalez-de-Peredo, A., Monsarrat, B., Girard, J.P., Cayrol, C., 2012. IL-33 is processed into mature bioactive forms by neutrophil elastase and cathepsin G. Proc. Natl. Acad. Sci. USA 109, 1673–1678. Leonardi-Bee, J., Pritchard, D., Britton, J., 2006. Asthma and current intestinal parasite infection: systematic review and meta-analysis. Am. J. Respir. Crit. Care Med. 174, 514–523. Lima, C., Perini, A., Garcia, M.L., Martins, M.A., Teixeira, M.M., Macedo, M.S., 2002. Eosinophilic inflammation and airway hyper-responsiveness are profoundly inhibited by a helminth (Ascaris suum) extract in a murine model of asthma. Clin. Exp. Allergy 32, 1659–1666. Liu, F.T., Yang, R.Y., Hsu, D.K., 2012. Galectins in acute and chronic inflammation. Ann. N.Y. Acad. Sci. 1253, 80–91. Maizels, R.M., Hewitson, J.P., 2012. Immune recognition of parasite glycans. In: Kosma, P., Müller-Loennies, S. (Eds.), Anticarbohydrate Antibodies – From Molecular Basis to Clinical Application. Springer, New York and Vienna, pp. 161–180. Maizels, R.M., Hewitson, J.P., Murray, J., Harcus, Y.M., Dayer, B., Filbey, K.J., Grainger, J.R., McSorley, H.J., Reynolds, L.A., Smith, K.A., 2012. Immune modulation and modulators in Heligmosomoides polygyrus infection. Exp. Parasitol. 132, 76–89. Mallevaey, T., Fontaine, J., Breuilh, L., Paget, C., Castro-Keller, A., Vendeville, C., Capron, M., Leite-de-Moraes, M., Trottein, F., Faveeuw, C., 2007. Invariant and noninvariant natural killer T cells exert opposite regulatory functions on the immune response during murine schistosomiasis. Infect. Immun. 75, 2171– 2180. Manoury, B., Gregory, W.F., Maizels, R.M., Watts, C., 2001. Bm-CPI-2, a cystatin homolog secreted by the filarial parasite Brugia malayi, inhibits class II MHCrestricted antigen processing. Curr. Biol. 11, 447–451. Marsland, B.J., Camberis, M., Le Gros, G., 2005. Secretory products from infective forms of Nippostrongylus brasiliensis induce a rapid allergic airway inflammatory response. Immunol. Cell Biol. 83, 40–47. Massacand, J.C., Stettler, R.C., Meier, R., Humphreys, N.E., Grencis, R.K., Marsland, B.J., Harris, N.L., 2009. Helminth products bypass the need for TSLP in Th2 immune responses by directly modulating dendritic cell function. Proc. Natl. Acad. Sci. USA 106, 13968–13973. McCoy, K.D., Stoel, M., Stettler, R., Merky, P., Fink, K., Senn, B.M., Schaer, C., Massacand, J., Odermatt, B., Oettgen, H.C., Zinkernagel, R.M., Bos, N.A., Hengartner, H., Macpherson, A.J., Harris, N.L., 2008. Polyclonal and specific antibodies mediate protective immunity against enteric helminth infection. Cell Host Microbe 4, 362–373. McSorley, H.J., Gaze, S., Daveson, J., Jones, D., Anderson, R.P., Clouston, A., Ruyssers, N.E., Speare, R., McCarthy, J.S., Engwerda, C.R., Croese, J., Loukas, A., 2011. Suppression of inflammatory immune responses in celiac disease by experimental hookworm infection. PLoS One 6, e24092. McSorley, H.J., Maizels, R.M., 2012. Helminth infections and host immune regulation. Clin. Microbiol. Rev. 25, 585–608. McSorley, H.J., O’Gorman, M.T., Blair, N., Sutherland, T.E., Filbey, K.J., Maizels, R.M., 2012. Suppression of type 2 immunity and allergic airway inflammation by secreted products of the helminth Heligmosomoides polygyrus. Eur. J. Immunol. 42, 2667–2682. Molehin, A.J., Gobert, G.N., McManus, D.P., 2012. Serine protease inhibitors of parasitic helminths. Parasitology 139, 681–695. Molloy, M.J., Bouladoux, N., Belkaid, Y., 2012. Intestinal microbiota: shaping local and systemic immune responses. Semin. Immunol. 24, 58–66. Moser, M., Murphy, K.M., 2000. Dendritic cell regulation of TH1–TH2 development. Nat. Immunol. 1, 199–205. Motomura, Y., Wang, H., Deng, Y., El-Sharkawy, R.T., Verdu, E.F., Khan, W.I., 2009. Helminth antigen-based strategy to ameliorate inflammation in an experimental model of colitis. Clin. Exp. Immunol. 155, 88–95. 309 Mulvenna, J., Hamilton, B., Nagaraj, S.H., Smyth, D., Loukas, A., Gorman, J.J., 2009. Proteomics analysis of the excretory/secretory component of the blood-feeding stage of the hookworm, Ancylostoma caninum. Mol. Cell. Proteomics 8, 109–121. Nisbet, A.J., Smith, S.K., Armstrong, S., Meikle, L.I., Wildblood, L.A., Beynon, R.J., Matthews, J.B., 2010. Teladorsagia circumcincta: activation-associated secreted proteins in excretory/secretory products of fourth stage larvae are targets of early IgA responses in infected sheep. Exp. Parasitol. 125, 329–337. Nisbet, A.J., Zarlenga, D.S., Knox, D.P., Meikle, L.I., Wildblood, L.A., Matthews, J.B., 2011. A calcium-activated apyrase from Teladorsagia circumcincta: an excretory/ secretory antigen capable of modulating host immune responses? Parasite Immunol. 33, 236–243. Nono, J.K., Pletinckx, K., Lutz, M.B., Brehm, K., 2012. Excretory/secretory-products of Echinococcus multilocularis larvae induce apoptosis and tolerogenic properties in dendritic cells in vitro. PLoS Negl. Trop. Dis. 6, e1516. Ostanin, D.V., Bao, J., Koboziev, I., Gray, L., Robinson-Jackson, S.A., KosloskiDavidson, M., Price, V.H., Grisham, M.B., 2009. T cell transfer model of chronic colitis: concepts, considerations, and tricks of the trade. Am. J. Physiol. Gastrointest. Liver Physiol. 296, G135–146. Panda, S.K., Kumar, S., Tupperwar, N.C., Vaidya, T., George, A., Rath, S., Bal, V., Ravindran, B., 2012. Chitohexaose activates macrophages by alternate pathway through TLR4 and blocks endotoxemia. PLoS Pathog. 8, e1002717. Pearce, E.J., MacDonald, A.S., 2002. The immunobiology of schistosomiasis. Nat. Rev. Immunol. 2, 499–511. Quinnell, R.J., 2003. Genetics of susceptibility to human helminth infection. Int. J. Parasitol. 33, 1219–1231. Rabinovich, G.A., Baum, L.G., Tinari, N., Paganelli, R., Natoli, C., Liu, F.T., Iacobelli, S., 2002. Galectins and their ligands: amplifiers, silencers or tuners of the inflammatory response? Trends Immunol. 23, 313–320. Robinson, M.W., Alvarado, R., To, J., Hutchinson, A.T., Dowdell, S.N., Lund, M., Turnbull, L., Whitchurch, C.B., O’Brien, B.A., Dalton, J.P., Donnelly, S., 2012. A helminth cathelicidin-like protein suppresses antigen processing and presentation in macrophages via inhibition of lysosomal vATPase. FASEB J. 26, 4614–4627. Robinson, M.W., Donnelly, S., Hutchinson, A.T., To, J., Taylor, N.L., Norton, R.S., Perugini, M.A., Dalton, J.P., 2011. A family of helminth molecules that modulate innate cell responses via molecular mimicry of host antimicrobial peptides. PLoS Pathog. 7, e1002042. Ruyssers, N.E., De Winter, B.Y., De Man, J.G., Loukas, A., Pearson, M.S., Weinstock, J.V., Van den Bossche, R.M., Martinet, W., Pelckmans, P.A., Moreels, T.G., 2009. Therapeutic potential of helminth soluble proteins in TNBS-induced colitis in mice. Inflamm. Bowel Dis. 15, 491–500. Rzepecka, J., Siebeke, I., Coltherd, J.C., Kean, D.E., Steiger, C.N., Al-Riyami, L., McSharry, C., Harnett, M.M., Harnett, W., 2012. The helminth product, ES-62, protects against airway inflammation by resetting the Th cell phenotype. Int. J. Parasitol. (this issue). Schenk, U., Frascoli, M., Proietti, M., Geffers, R., Traggiai, E., Buer, J., Ricordi, C., Westendorf, A.M., Grassi, F., 2011. ATP inhibits the generation and function of regulatory T cells through the activation of purinergic P2X receptors. Sci. Signal. 4, ra12. Schnoeller, C., Rausch, S., Pillai, S., Avagyan, A., Wittig, B.M., Loddenkemper, C., Hamann, A., Hamelmann, E., Lucius, R., Hartmann, S., 2008. A helminth immunomodulator reduces allergic and inflammatory responses by induction of IL-10-producing macrophages. J. Immunol. 180, 4265–4272. Schramm, G., Mohrs, K., Wodrich, M., Doenhoff, M.J., Pearce, E.J., Haas, H., Mohrs, M., 2007. Cutting edge: IPSE/alpha-1, a glycoprotein from Schistosoma mansoni eggs, induces IgE-dependent, antigen-independent IL-4 production by murine basophils in vivo. J. Immunol. 178, 6023–6027. Segura, M., Su, Z., Piccirillo, C., Stevenson, M.M., 2007. Impairment of dendritic cell function by excretory-secretory products: a potential mechanism for nematode-induced immunosuppression. Eur. J. Immunol. 37, 1887–1904. Semnani, R.T., Venugopal, P.G., Mahapatra, L., Skinner, J.A., Meylan, F., Chien, D., Dorward, D.W., Chaussabel, D., Siegel, R.M., Nutman, T.B., 2008. Induction of TRAIL- and TNF-alpha-dependent apoptosis in human monocyte-derived dendritic cells by microfilariae of Brugia malayi. J. Immunol. 181, 7081–7089. Serradell, M.C., Guasconi, L., Cervi, L., Chiapello, L.S., Masih, D.T., 2007. Excretorysecretory products from Fasciola hepatica induce eosinophil apoptosis by a caspase-dependent mechanism. Vet. Immunol. Immunopathol. 117, 197–208. Smith, K.A., Harcus, Y., Garbi, N., Hammerling, G.J., Macdonald, A.S., Maizels, R.M., 2012. Type 2 innate immunity in helminth infection is induced redundantly and acts autonomously following CD11c+ cell depletion. Infect. Immun. 80, 3481– 3489. Steinfelder, S., Andersen, J.F., Cannons, J.L., Feng, C.G., Joshi, M., Dwyer, D., Caspar, P., Schwartzberg, P.L., Sher, A., Jankovic, D., 2009. The major component in schistosome eggs responsible for conditioning dendritic cells for Th2 polarization is a T2 ribonuclease (omega-1). J. Exp. Med. 206, 1681–1690. Strachan, D.P., 1989. Hay fever, hygiene, and household size. BMJ 299, 1259–1260. Summers, R.W., Elliott, D.E., Qadir, K., Urban Jr., J.F., Thompson, R., Weinstock, J.V., 2003. Trichuris suis seems to be safe and possibly effective in the treatment of inflammatory bowel disease. Am. J. Gastroenterol. 98, 2034–2041. Summers, R.W., Elliott, D.E., Urban Jr., J.F., Thompson, R., Weinstock, J.V., 2005a. Trichuris suis therapy in Crohn’s disease. Gut 54, 87–90. Summers, R.W., Elliott, D.E., Urban Jr., J.F., Thompson, R.A., Weinstock, J.V., 2005b. Trichuris suis therapy for active ulcerative colitis: a randomized controlled trial. Gastroenterology 128, 825–832. 310 H.J. McSorley et al. / International Journal for Parasitology 43 (2013) 301–310 Sutherland, T.E., Maizels, R.M., Allen, J.E., 2009. Chitinases and chitinase-like proteins: potential therapeutic targets for the treatment of T-helper type 2 allergies. Clin. Exp. Allergy 39, 943–955. Sutton, T.L., Zhao, A., Madden, K.B., Elfrey, J.E., Tuft, B.A., Sullivan, C.A., Urban Jr., J.F., Shea-Donohue, T., 2008. Anti-Inflammatory mechanisms of enteric Heligmosomoides polygyrus infection against trinitrobenzene sulfonic acidinduced colitis in a murine model. Infect. Immun. 76, 4772–4782. Terrazas, C.A., Sanchez-Munoz, F., Mejia-Dominguez, A.M., Amezcua-Guerra, L.M., Terrazas, L.I., Bojalil, R., Gomez-Garcia, L., 2011. Cestode antigens induce a tolerogenic-like phenotype and inhibit LPS inflammatory responses in human dendritic cells. Int. J. Biol. Sci. 7, 1391–1400. Trujillo-Vargas, C.M., Werner-Klein, M., Wohlleben, G., Polte, T., Hansen, G., Ehlers, S., Erb, K.J., 2007. Helminth-derived products inhibit the development of allergic responses in mice. Am. J. Respir. Crit. Care Med. 175, 336–344. Tudor, J.E., Pallaghy, P.K., Pennington, M.W., Norton, R.S., 1996. Solution structure of ShK toxin, a novel potassium channel inhibitor from a sea anemone. Nat. Struct. Biol. 3, 317–320. Walk, S.T., Blum, A.M., Ewing, S.A., Weinstock, J.V., Young, V.B., 2010. Alteration of the murine gut microbiota during infection with the parasitic helminth Heligmosomoides polygyrus. Inflamm. Bowel Dis. 16, 1841–1849. Wilson, M.S., Mentink-Kane, M.M., Pesce, J.T., Ramalingam, T.R., Thompson, R., Wynn, T.A., 2007. Immunopathology of schistosomiasis. Immunol. Cell Biol. 85, 148–154. Wirtz, S., Neufert, C., Weigmann, B., Neurath, M.F., 2007. Chemically induced mouse models of intestinal inflammation. Nat. Protoc. 2, 541–546. Yamazaki, S., Inaba, K., Tarbell, K.V., Steinman, R.M., 2006. Dendritic cells expand antigen-specific Foxp3+ CD25+ CD4+ regulatory T cells including suppressors of alloreactivity. Immunol. Rev. 212, 314–329. Yang, J., Zhao, J., Yang, Y., Zhang, L., Yang, X., Zhu, X., Ji, M., Sun, N., Su, C., 2007. Schistosoma japonicum egg antigens stimulate CD4 CD25 T cells and modulate airway inflammation in a murine model of asthma. Immunology 120, 8–18. Yatsuda, A.P., Krijgsveld, J., Cornelissen, A.W., Heck, A.J., de Vries, E., 2003. Comprehensive analysis of the secreted proteins of the parasite Haemonchus contortus reveals extensive sequence variation and differential immune recognition. J. Biol. Chem. 278, 16941–16951. Young, N.D., Jex, A.R., Li, B., Liu, S., Yang, L., Xiong, Z., Li, Y., Cantacessi, C., Hall, R.S., Xu, X., Chen, F., Wu, X., Zerlotini, A., Oliveira, G., Hofmann, A., Zhang, G., Fang, X., Kang, Y., Campbell, B.E., Loukas, A., Ranganathan, S., Rollinson, D., Rinaldi, G., Brindley, P.J., Yang, H., Wang, J., Gasser, R.B., 2012. Whole-genome sequence of Schistosoma haematobium. Nat. Genet. 44, 221–225. Younis, A.E., Geisinger, F., Ajonina-Ekoti, I., Soblik, H., Steen, H., Mitreva, M., Erttmann, K.D., Perbandt, M., Liebau, E., Brattig, N.W., 2011. Stage-specific excretory-secretory small heat shock proteins from the parasitic nematode Strongyloides ratti–putative links to host’s intestinal mucosal defense system. FEBS J. 278, 3319–3336. Zaccone, P., Burton, O., Miller, N., Jones, F.M., Dunne, D.W., Cooke, A., 2009. Schistosoma mansoni egg antigens induce Treg that participate in diabetes prevention in NOD mice. Eur. J. Immunol. 39, 1098–1107. Zaccone, P., Burton, O.T., Gibbs, S., Miller, N., Jones, F.M., Dunne, D.W., Cooke, A., 2010. Immune modulation by Schistosoma mansoni antigens in NOD mice. Effects on both innate and adaptive immune systems. J. Biomed. Biotechnol. 2010, 795210. Zaccone, P., Burton, O.T., Gibbs, S.E., Miller, N., Jones, F.M., Schramm, G., Haas, H., Doenhoff, M.J., Dunne, D.W., Cooke, A., 2011. The S. mansoni glycoprotein omega-1 induces Foxp3 expression in NOD mouse CD4(+) T cells. Eur. J. Immunol. 41, 2709–2718. Zaccone, P., Fehervari, Z., Jones, F.M., Sidobre, S., Kronenberg, M., Dunne, D.W., Cooke, A., 2003. Schistosoma mansoni antigens modulate the activity of the innate immune response and prevent onset of type 1 diabetes. Eur. J. Immunol. 33, 1439–1449. Zang, X., Maizels, R.M., 2001. Serine proteinase inhibitors from nematodes and the arms race between host and pathogen. Trends Biochem. Sci. 26, 191–197. Zang, X., Yazdanbakhsh, M., Jiang, H., Kanost, M.R., Maizels, R.M., 1999. A novel serpin expressed by blood-borne microfilariae of the parasitic nematode Brugia malayi inhibits human neutrophil serine proteinases. Blood 94, 1418–1428. Zheng, X., Hu, X., Zhou, G., Lu, Z., Qiu, W., Bao, J., Dai, Y., 2008. Soluble egg antigen from Schistosoma japonicum modulates the progression of chronic progressive experimental autoimmune encephalomyelitis via Th2-shift response. J. Neuroimmunol. 194, 107–114. Zhou, Z.H., Chen, Y., Zhang, L., Wang, K., Guo, J., Huang, Z., Zhang, B., Huang, W., Jin, K., Dou, T., Hasegawa, M., Wang, L., Zhang, Y., Zhou, J., Tao, L., Cao, Z., Li, Y., Vinar, T., Brejova, B., Brown, D., Li, M., Miller, D.J., Blair, D., Zhong, Y., Chen, Z., Liu, F., Hu, W., Wang, Z.Q., Zhang, Q.H., Song, H.D., Chen, S., Xu, X., Xu, B., Ju, C., Huang, Y., Brindley, P.J., McManus, D.P., Feng, Z., Han, Z.G., Lu, G., Ren, S., Wang, Y., Gu, W., Kang, H., Chen, J., Chen, X., Chen, S., Wang, L., Yan, J., Wang, B., Lv, X., Jin, L., Wang, B., Pu, S., Zhang, X., Zhang, W., Hu, Q., Zhu, G., Wang, J., Yu, J., Wang, J., Yang, H., Ning, Z., Beriman, M., Wei, C.L., Ruan, Y., Zhao, G., Wang, S., Liu, F., Zhou, Y., Wang, Z.Q., Lu, G., Zheng, H., Brindley, P.J., McManus, D.P., Blair, D., Zhang, Q.H., Zhong, Y., Wang, S., Han, Z.G., Chen, Z., Wang, S., Han, Z.G., Chen, Z., 2009. The Schistosoma japonicum genome reveals features of host-parasite interplay. Nature 460, 345–351.