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Send Orders for Reprints to [email protected] Current Medicinal Chemistry, 2014, 21, ????-???? 1 Condrosulf®: Structural Characterization, Pharmacological Activities and Mechanism of Action Nicola Volpi* Department of Life Sciences, University of Modena and Reggio Emilia, Italy Abstract: Condrosulf® is a pharmaceutical formulation containing chondroitin sulfate (CS) as an active component possessing high quality and purity and standardized properties. CS is currently applied as a SYSADOA (Symptomatic Slow Acting Drug for Osteoarthritis) agent in Europe in the treatment of osteoarthritis (OA). Furthermore, Condrosulf® and pharmaceutical grade CS have also been proven to possess structure-modifying effects belonging to the S/DMOAD (structure/disease modifying anti-osteoarthritis drug) class. This review summarizes current knowledge on CS/Condrosulf® structure and its properties, its pharmacological activity as proved by many clinical trials and metaanalysis studies and focuses attention on its mechanisms of action in the pathophysiology of osteoarthritic joint tissues. Finally, future perspectives are discussed in connection with the possibility to apply new outcome measures, such as MRI and biomarkers, which can yield important advances in the use of Condrosulf® as well as the development of new drugs with different structures useful in particular for the treatment of inflammatory symptoms and able to retard the progression of arthritis. Keywords: Condrosulf®, chondroitin sulfate, glycosaminoglycans, osteoarthritis. INTRODUCTION ® Condrosulf (manufactured by IBSA, Institut Biochimique SA, Switzerland) is a drug containing CS as its active component. CS is a natural heterogeneous polysaccharide belonging to the biomacromolecule family of GAGs. In fact, CS as a component of various PGs not only located on the ECM, such as cartilages, skin, blood vessels, ligaments and tendons, but also at cellular level [1]. The CS polymer is constituted of repeating non-sulfated and various sulfated disaccharide residues formed of GlcA and of GalNAc linked by (1->3) bonds. The various disaccharides are attached to one another by (1->4) links [2]. Depending on the position of the sulfate groups, C2 of GlcA (very rarely on C3), C4 and/or C6 of the GalNAc unit, different disaccharides and CS with heterogeneous carbohydrate backbones and charge density are known (Fig. 1). In fact, the various sulfated disaccharides constitute, in different percentages, the building block sequence of CS polysaccharide backbone, in relation to specific animal sources such as tissues, organs and biological fluids, and pathological conditions [3]. CS is a strong negatively charged polymer due to the ionization of sulfate groups and of the carboxyl groups of GlcA. As a consequence, CS-PGs of articular cartilage are responsible for the ECM viscoelastic and gelling properties due to their high degree of hydration [4]. However, recent glycobiology studies suggest that the complex CS polysaccharide and its related macromolecular derived PGs possess, along with their structural functions, the capacity to regulate *Address correspondence to this author at the Department of Life Sciences. University of Modena & Reggio Emilia. Via Campi 213/D. 41100 Modena, Italy; Tel: 0039 (0)59 2055543; Fax: 0039 (0)59 2055548; E-mail: [email protected] 0929-8673/14 $58.00+.00 many cellular and physiological processes, such as the development of central nervous system, cellular differentiation and migration, cell division and morphogenes, wound repair, infective events and growth factor activity [3, 5-8]. Fig. (1). Structures of typical disaccharides forming chondroitin sulfate chains. Sulfate groups may be located in position 2 of the glucuronic acid (and very rarely in position 3) or/and on the C4 and C6 of the N-acetyl-galactosamine unit. PHARMACEUTICAL GRADE CHONDROITIN SULFATE IS THE ACTIVE DRUG IN CONDROSULF® CS is a natural biomacromolecule extracted and purified from animal tissues generally by patented and property processes [2]. As a consequence, along with CS natural structural complexity and heterogeneity (see below), factors such as source material, manufacturing processes, purity and physico-chemical properties of the final product (and many others) contribute to its biological and pharmacological activity. CS has a complex macromolecular structure and characteristics strictly related to the tissue, organ and species. As a consequence, the determination of origin, structure and physico-chemical properties is a key point of CS quality. To date, © 2014 Bentham Science Publishers 2 Current Medicinal Chemistry, 2014, Vol. 21, No. 1 commercial CS is generally produced from cartilages of bovine [9], porcine [9], chicken [10], or cartilaginous fishes such as sharks [11] and skate [12, 13]. Moreover, other sources are useful for CS production such as fish bones [14] and a combination of the above mentioned raw material may be used to produce CS having distinctive properties. CS samples extracted from different sources have polysaccharide chains composed of various percentages of disaccharides bearing sulfate groups in different positions [15]. Biosynthetic processes generate a great heterogeneity of the number and position of sulfate groups responsible for an overall charge density variability and for the presence of low- and/or highly-sulfated sequences inside the polymeric backbone. Moreover, CS is biosynthetized as a polydisperse macromolecule possessing different molecular mass values not only depending on the source but also on physiological and pathological conditions. The number of disaccharide units and related molecular mass parameters are other key factors influencing CS biological and pharmacological activities [16-19]. Finally, generally property manufacturing processes may generate further alterations of the CS structure and physico-chemical properties, in particular molecular mass and charge density values, together with the final products possessing various grades of purity. In fact, along with the yield, CS quality and purity may vary according to the extraction and purification processes and/or tissue sources. Due to these variations, CS produced from animal tissues may possess different biological properties and pharmacological abilities. The evaluation of the CS origin, structure, physicochemical properties, its content and purity are of paramount importance when preparations are manufactured for pharmaceutical and nutraceutical applications. As a consequence, specific and sensitive analytical techniques such as accurate and reproducible quantitative assays are required, along with appropriate and highly purified reference standards of wellknown and standardized properties and structures [15, 20]. CS for pharmaceutical applications is under strict evaluation for quality, purity, content, structural characterization and physico-chemical parameters generally by Pharmacopoeia analytical indications, validated and published procedures and assays [see References 15 and 20 for an overview of the analytical approaches to pharmaceutical grade CS]. This feature is a key point to guarantee active ingredient quality and therapeutic reproducibility, purity and safe use of the drug. In fact, viruses or prions may be present in CS samples [21, 22] related in particular to bovine, porcine and chicken origin, and specific purification procedures are required for their possible elimination [22]. Moreover, proteins and their fragments derived from chemical and/or enzymatic treatment are generally present also in high concentration, reaching 3-5% [15, 20, 23, 24]. This is also related to the nature of CS as PG and to the difficulty to eliminate protein residues covalently linked to the CS backbone. The presence of proteins (and related fragments) poses the problem of possible IgG-mediated intolerances and IgE-mediated allergies. Additionally, nucleic acids, DNA and RNA, and their fragments derived from chemical treatment are also generally present [15, 20, 23-25]. Finally, KS was detected in batches from shark cartilage, averaging ~16% of the total GAGs Nicola Volpi [26]. This is most important, considering that KS is immunogenic, being able to produce immunological responses in humans [27, 28]. On the contrary, CS for nutraceutical preparations is not subject to such strict regulations. In fact, in a recent study [20], the CS content reported on the label specifications of ten European products was found to conform to just four samples analyzed. These results were found comparable with those of other studies reporting poor CS quality and failure to comply with the label claim such as a great CS source variability in products present in USA, Korean and Japanese markets [see 20 for review]. CLINICAL STUDIES Many clinical trials have been performed to establish Condrosulf®/CS dose regimen, safety and efficacy (Table 1). In a study performed in 1996 [29], Condrosulf® was orally administered for 3 months to 61 subjects affected by hip, knee and/or finger joints OA. Concomitant NSAID-therapy consumption was significantly reduced by 72% during the three months of CS administration. This study demonstrated an effective reduction in the daily NSAID use by concomitant CS treatment. No risk of worsening of the OA symptoms and no serious side effects were observed. In another study carried out in 1996 [30], the efficacy of CS was assessed compared to NSAID drug diclofenac sodium in a randomized, multicenter, double blind, double dummy, medium/long term clinical trial in 146 patients suffering from knee OA. Lequesne index, spontaneous pain, pain on load and paracetamol consumption were evaluated. Compared to NSAID, CS was found to gradually reduce OA symptoms, lasting even after the end of treatment. In fact, subjects treated with the NSAID showed a rapid decrease of clinical symptoms, rapidly reappearing at the end of treatment. On the contrary, the efficacy of CS appeared later in time also continuing for a long time even after the end of administration. A trial performed in 1998 [31] confirmed the capacity of Condrosulf® to stop femoro-tibial joint space narrowing acting as a SYSADOA drug. Four further reviews published in the same year underlined a few key activities of Condrosulf® such as its efficacy and tolerability [32], and its properties as a SYSADOA [33, 34] and S/DMOAD molecules [35] (Table 1). A double blind, prospective, placebo controlled multicenter clinical study was undertaken in 2001 to determine the efficacy and safety of CS in patients suffering from femorotibial OA [36]. A trend showing CS efficacy compared to the placebo was observed after 3 months of treatment and persistent post-treatment for another month. However, due to the non significant results, further investigations were required by the authors to confirm this trend. A new trial in 2002 evaluated the progression of finger joint OA by measuring anatomical changes recorded by standard radiographs [37]. 34 patients were included in a double-blind, randomized, placebo-controlled trial receiving Condrosulf® and monitored for 3 years. Progressive OA was found to be more limited in the CS treatment group and few patients developed erosive OA (Table 1). Condrosulf® The efficacy and tolerability of orally administered CS in patients affected by knee OA were investigated in 2004 in a 3-month, twice-yearly, intermittent treatment [38]. OA was evaluated by radiological progression of the medial femorotibial joint space width along with clinical and biological tolerability. Oral CS was able to improve knee function and to decrease pain. Moreover, the 3-month intermittent treatment twice a year also supported prolonged CS clinical efficacy associated with symptom-modifying agents for OA. Finally, the capacity of CS to improve the femoro-tibial joint space narrowing also suggested further evidence of its structure-modifying capacities in knee OA. A further trial performed in 24 patients having erosive OA of the hands [39] evaluated the effect of 800 mg/die of CS/naproxen combination versus naproxen alone over a 2 years period. This study confirmed the capacity of oral CS to improve some features of erosive OA (Table 1). A randomized, double-blind, placebo-controlled trial was conducted in 2005 [40]. 300 patients affected by knee OA received 800 mg Condrosulf® once daily for 2 years. The primary outcome was considered as the joint space loss over the 2 years period evaluated by the posteroanterior radiograph of the knee in flexion. Pain and function were included in secondary outcomes. The authors observed a reduction in the radiographic knee OA progression determined by longterm treatment with Condrosulf®. A 2-year, randomized, placebo-controlled trial of CS treatment in patients suffering from symptomatic knee OA was published in 2007 [41]. Pain, investigator's assessment and quality of life were found to be slightly improved in patients treated with CS (Table 1), even if it failed to reduce joint space loss. CS was able to significantly improve knee joint swelling in an exploratory post hoc analysis of GAIT in subjects affected by OA [42]. A further two-year trial was conducted in 2009 to assess the effect of Condrosulf® on the radiographic progression of knee OA associated with the modification of symptoms [43]. Condrosulf® was suggested to be a diseasemodifying agent in patients with knee OA by its long-term combined structure-modifying and symptom-modifying capacities (Table 1). Four recent publications not only confirmed the efficacy and safety of CS as a SYSADOA in patients suffering from knee OA in the absence [44] and in the presence of plantar psoriasis [45], but also its capacity to improve hand pain and function in subjects suffering of OA of the hand [46], as well as its protective effect on joint structure [47] (Table 1). Several other clinical trials have been performed with CS in combination with other active compounds, especially GlcN (Table 2). In particular, considering the large clinical GAIT trial [48], exploratory analyses suggested that CS may be active in a subgroup of patients affected by moderate-tosevere knee pain, further confirmed by subsequent studies [49]. To date, the first meta-analysis study was performed in 2000 [50] in which 7 trials on 372 patients taking CS were considered (Table 3). Several other meta-analyses of clinical trials have been published since that first report (Table 3). CS, alone or in combination with other agents, was able to reduce joint pain and to slow down the rate of reduction of joint space in patients suffering from OA. Contrary to these Current Medicinal Chemistry, 2014, Vol. 21, No. 1 3 positive reports, data provided by only two meta-analysis studies by Wandel et al. [51] and Reichenbach et al. [52] showed a minimal or nonexistent benefit from CS administration. However, many criticisms have been addressed to these studies, such as the huge heterogeneity between trials [53] considering that treatment is known to vary in relation to disease severity, as confirmed by Sawitzke et al. [49] and the high variability in the origin, potency and purity of CS samples used in the evaluated studies, as previously discussed. Meta-analysis based on no evidence of heterogeneity across the trials showed positive effects of CS as a SYSADOA and S/DMOAD agent (Table 3). CS MECHANISM OF ACTION As an important biomacromolecule at cellular, tissue and metabolic level, besides its conventional structural roles, CS possesses many important biological functions. In fact, CS is involved in inflammatory processes, cell proliferation and differentiation, cell migration, tissue morphogenesis, organogenesis, infection and wound repair [3, 54, 55]. As far as its pharmacological mechanism of action is concerned, many studies have focused great attention on its antiinflammatory capacity in addition to other activities [7, 5661]. Inflammation is a protective systemic and local response caused by physical damage or infection by microorganisms. The main biological function of inflammation is to eliminate the noxious factors, and to promote tissue repair and wound healing. Inflammation also establishes memory enabling the host to cause a rapid and highly specific response upon a possible future contact [62] (Fig. 2). A complex network of biochemical pathways, including catabolic factors/mediators and cytokines established between the different joint tissues and the cartilage, is involved in tissue changes and remodeling [61]. Along with the destruction of the articular cartilage, synovial inflammation is developed as a secondary phenomenon related to multiple factors, and these modifications are also correlated to the altered metabolism of osteoblasts. The above illustrated clinical trials have demonstrated the capacity of CS to reduce pain improving articular function, to decrease joint swelling and effusion, and to prevent joint space narrowing of the cartilages more effectively compared to placebo. Accordingly, CS has been defined as a SYSADOA and S/DMOAD compound (see above reported studies and related References). The beneficial effects of CS in patients affected by OA result from different activities, in particular the documented reduction of the NF-B nuclear translocation, decrease in the production of pro-inflammatory cytokines IL-1 and TNF- and reduction in the expression and activity of NOS-2 and COX-2 (Fig. 3). Moreover, other documented activities of CS may contribute to its efficacy in patients, such as its capacity to increase the synthesis of articular cartilage PG, reduce the apoptosis of chondrocytes and the synthesis and/or activity of MMPs [59, 60]. Besides other receptors, toll-like receptors 1-13 (TLR113) are the most frequently activated membrane PRRs in immune cells. The activation of TLR1-13 leads to the phosphorylation of extracellular signal-regulated kinases capable to produce a molecular cascade inducing the release of NFB and its translocation to the nucleus [63]. Inside cell 4 Current Medicinal Chemistry, 2014, Vol. 21, No. 1 Table 1. Nicola Volpi Clinical Trials With Condrosulf® /Chondroitin Sulfate (CS) Under Investigation Year Study N° of Patients Daily Dose 1996 Patients suffering from OA of the hip, knee and/or finger joints were included in this open, multicenter, phase IV trial. Patients were treated with Condrosulf® for 3 months 61 1996 The clinical trial was performed in comparison with diclofenac sodium in a randomized, multicenter, double blind, double dummy, medium/long term clinical study in patients with knee OA 146 1998 This is a double-blind, randomized, placebo-controlled clinical trial for a total study period of 12 months 1998 This was a multicenter randomized, double-blind, controlled study performed to compare the efficacy and tolerability of Condrosulf® in patients with mono or bilateral knee OA 1998 Patients with OA of the knee were treated with Condrosulf® in a randomized, double-blind, placebo-controlled study, performed in two centers for a 6-month study period 1998 This trial assessed the clinical, radiological and biological efficacy and tolerability of Condrosulf® in patients suffering from knee OA. This was a 1year, randomized, double-blind, controlled pilot study on patients with symptomatic knee OA 1998 This is a randomized, double-blind, placebo-controlled trial carried out to assess the S/DMOAD properties of Condrosulf® in OA 2001 The efficacy and safety of CS per os was assessed compared to the placebo, in a double blind, randomized, parallel group study, with 3 months’ treatment followed by a 3-month post-treatment period, in patients with femoro-tibial OA 2002 This study evaluated the progression of OA using scoring systems based on the anatomical changes recorded in the finger joints on standard radiographs. 34 patients were included in a randomized, double-blind placebo-controlled trial receiving Condrosulf® and monitored for 3 years Results Key Feature Reference 800 mg A significant reduction of 72% in the daily NSAID consumption by Condrosulf® is effecconcomitant CS-therapy was obtive over 3 months vs served with no risk of deterioration NSAID/placebo of the patients' symptoms and serious side effects [29] 1200 mg The therapeutic response of CS CS effective for 6 appeared later in time but lasted months vs placebo, 3 for up to 3 months after the end of months carryover treatment. [30] 800 mg This study confirms the SYSACondrosulf® is able to DOA effect of Condrosulf® with stop femoro-tibial joint an excellent clinical and biological space narrowing profile and tolerance [31] 127 1200 mg The treatment was very well tolerated also indicating that CS favors the improvement of subjective Condrosulf® is effecsymptoms, improving joint mobil- tive at 3 months vs ity. 1200 mg CS as a single daily placebo dose does not differ from that of 3 x 400 mg daily dose [32] 80 800 mg Condrosulf® effective over 6 months vs placebo [33] 800 mg The results obtained confirmed that oral CS is an effective and safe SYSADOA for the treatment Condrosulf® effective of knee OA. CS might also be able over 1 year vs placebo to stabilize the joint space width and to modulate bone and joint metabolism. [34] 1200 mg In the Condrosulf® group a signifiTreated patients were cant decrease in the number of protected against eropatients with new "erosive" OA sive evolution finger joints was observed [35] 1000 mg A trend towards the efficacy of CS compared to the placebo with good All variables considtolerability after 3 months’ treat- ered tended towards ment, and persistent post-treatment greater improvement in efficacy for one month, was obthe CS group served [36] 1200 mg Conventional radiographs used to score OA was less progressive in the CS the progression of treatment group and few patients finger joint OA aldeveloped "erosive" OA lowed the determination of the S/DMOAD effect of Condrosulf® [37] 110 42 119 130 34 The observed results strongly suggested that CS/Condrosulf® acts as a SYSADOA in knee OA Condrosulf® Current Medicinal Chemistry, 2014, Vol. 21, No. 1 5 (Table 1) contd…. Year Study N° of Patients Daily Dose Results Key Feature Reference Oral CS decreases pain and improves knee function. The 3-month twice-yearly intermittent CS administration does support the prolonged effect associated with symptom-modifying agents for OA The inhibitory effect of CS on the radiological progression of medial femoro-tibial joint space narrowing suggests further evidence of its structuremodifying properties in knee OA [38] [39] 2004 This trial investigated the efficacy and tolerability of a 3-month, twice-yearly, intermittent treatment with oral CS in knee OA patients 2004 The aim of this study was to evaluate the effect of CS per os plus naproxen versus naproxen over 2 years in patients with erosive OA of the hands 24 800 mg Contrary to the treated patients, The partial efficacy of the untreated group showed sig- oral CS in improving nificant worsening in erosion and some aspects of erosive OA was conphysician and patient global asfirmed sessment scores 2005 A randomized, double-blind, placebocontrolled trial, including patients with knee OA treated with Condrosulf® or a placebo once daily for 2 years. The primary outcome was joint space loss over 2 years. Secondary outcomes included pain and function 300 800 mg Long-term treatment with Condro- The clinical relevance sulf® may retard radiographic of the observed strucprogression in patients with OA of tural results has to be further evaluated the knee [40] 2007 A 24-week, randomized placebocontrolled trial of CS in patients with symptomatic knee OA measured on a visual analogue scale 1000 mg CS was slightly more This study failed to show an effi- effective than the placacy of CS as regards the primary cebo on pain, investigator's assessment and criteria considered quality of life [41] 2007 An exploratory post hoc analysis of GAIT (Glucosamine/chondroitin Arthritis Intervention Trial) patients 1200 mg Patients taking CS This study suggested that the efwere observed to have fect of CS on joint swelling oca statistically significurred more often in patients with cant improvement in milder pain knee joint swelling [42] 2009 Performed to assess the long-term (two-year) effects, of Condrosulf® on the radiographic progression of, and symptom changes associated with, knee OA 800 mg The intent-to-treat analysis demCondrosulf® could be onstrated a significant reduction in an S/DMOAD agent in minimum joint space width loss in patients with knee OA the Condrosulf® group [43] 2010 The aim of this trial was to assess the efficacy of CS on symptomatic knee OA associated with psoriasis 800 mg This study confirmed the efficacy The use of CS could and safety of CS as a SYSADOA represent a special in patients with knee OA and benefit in patients with showed that CS improves plantar OA and psoriasis psoriasis [45] 2011 The symptomatic effects of highly purified CS therapy in patients with OA of the hands were evaluated 800 mg CS improves hand pain and funcCS improves hand pain tion in patients with symptomatic and function in patients OA of the hands and shows a good with symptomatic OA safety profile [46] 2011 The effect of CS on cartilage volume loss, subchondral bone marrow lesions, synovitis and disease symptoms in patients with knee OA was evaluated 69 800 mg A joint structure proCS treatment significantly reduced tective effect of CS the cartilage volume loss in knee was confirmed providOA starting at 6 months of treating new information on ment, and subchondral bone marits mode of action in row lesions at 12 months knee OA [47] 2012 This study evaluated the correlation between clinical symptoms and cartilage volume through MRI in patients with knee OA after 48 weeks of treatment with CS 43 1000 mg 120 307 1583 622 129 162 800 mg The total cartilage volume increased in the CS group, as opposed to a loss in the placebo CS acts as an S/DMOAD in knee OA [44] 6 Current Medicinal Chemistry, 2014, Vol. 21, No. 1 Table 2. Clinical Trials With Condrosulf®/Chondroitin Sulfate (CS) and Glucosamine (GlcN) Under Investigation Year Study 1999 This was a 16-week randomized, double-blind, placebo-controlled crossover trial of a combination of GlcN, CS and manganese ascorbate in degenerative joint disease of the knee or low back 2001 The effect of GlcN and CS taken for twelve weeks on subjects diagnosed with capsulitis, disk displacement, disk dislocation, or painful OA of the temporo-mandibular joint was assessed 2006 This was a multicenter, double-blind, placebo- and celecoxib-controlled GlcN/CS Arthritis Intervention Trial (GAIT) to evaluate their efficacy and safety as a treatment for knee pain from OA 2007 This was a double-blind, placebocontrolled, randomized clinical trial lasting 12 months. Participants included patients with knee OA randomized to either the GlcN/CS or placebo group 2008 2010 Nicola Volpi This study was undertaken to evaluate the effect of GlcN/CS, alone or in combination, as well as celecoxib and placebo on progressive loss of joint space width in patients with knee OA To evaluate the efficacy and safety of GlcN/CS, alone or in combination, as well as celecoxib and placebo on painful knee OA over 2 years N° of Patients 34 45 1583 89 572 662 Daily Dose Results Key Feature Reference 1200 mg Knee OA symptoms were relieved as demonstrated by the summary disease score, patient assessment of treatment effect, visual analog scale for pain recorded during clinic visits and in a diary and physical examination score The combination therapy relieves symptoms of knee OA [74] 1200 mg Subjects taking CS/GlcN experienced improvements in their pain as measured by one index of the McGill Pain Questionnaire and in the number of daily over-the-counter medications needed Additional studies are required to evaluate the clinical effectiveness of CS/GlcN [75] 1200 mg GlcN/CS did not reduce pain effecOverall, GlcN/CS were not tively in the overall significantly better than the group of patients with placebo in reducing knee pain OA of the knee. by 20 percent. However, for Exploratory analyses patients with moderate-tosuggest that the comsevere pain at baseline, the rate bination of GlcN/CS of response was significantly may be effective in higher with combined therapy the subgroup of pathan with the placebo. tients with moderateto-severe knee pain [48] 1200 mg WOMAC function and pain did not differ significantly between the groups at 6- or 12month follow-up. There were also no significant differences between the groups in knee strength The GlcN/CS group was not superior to the placebo group as regards function, pain, or mobility [76] 1200 mg No statistically significant differences in mean joint space Knees with Kellwidth loss were observed in any treatment group compared gren/Lawrence grade 2 radiographic OA with the placebo group. Howappeared to have the ever, a trend towards improvement with respect to the greatest potential for placebo group was observed. modification by these treatments The power of the study was diminished by the limited sample size [49] 1200 mg Over 2 years, no treatment achieved a clinically important difference in WOMAC pain or function as compared with the placebo. Adverse reactions were similar among treatment groups and serious adverse events were rare for all treatments [77] Compared to the placebo, no statistically significant differences were observed Condrosulf® Current Medicinal Chemistry, 2014, Vol. 21, No. 1 7 (Table 2) contd…. Year Study 2014 A double-blind randomized placebocontrolled clinical trial with 2-year follow-up was performed to determine the capacity of GlcN and/or CS to reduce joint space narrowing and pain in patients with symptomatic knee OA Table 3. 605 Daily Dose 800 mg Results Key Feature The dietary supplement comGlcN/CS combinabination (GlcN/CS) resulted in tion resulted in a a statistically significant restatistically signifiduction of 2-year joint space cant reduction in joint narrowing compared to the space narrowing at 2 placebo years Reference [78] Meta-analysis of Clinical Trials With Condrosulf®/Chondroitin Sulfate (CS) Under Investigation Year Study 2000 The efficacy of CS in the treatment of OA on the basis of a metaanalysis of controlled clinical trials was evaluated 2003 N° of Patients To assess the structural and symptomatic efficacy of oral CS/GlcN in knee OA through independent meta-analyses of their effects on joint space narrowing Agent Size Results Reference CS 7 trials of 372 patients taking CS were enrolled in the metaanalysis CS may be useful in OA but further investigations in larger cohorts of patients for longer time periods are needed to prove its usefulness as a SYSADOA [50] CS and GlcN An exhaustive systematic research of randomized, placebo-controlled clinical trials published or performed between January 1980 and March 2002. 1775 patients were analyzed in 15 selected studies This study demonstrates the structural efficacy of GlcN and indistinguishable symptomatic efficacies for both compounds [79] The symptomatic benefit of CS is minimal or nonexistent. Heterogeneity among the trials made initial interpretation of results difficult, and exploring sources of heterogeneity in meta-regression and stratified analyses may be unreliable [52] 20 trials, 3846 patients, contributed to this metaanalysis 2007 To determine the effects of CS on pain in patients with OA. CS 2007 To determine the short-term painrelieving effects of seven commonly used pharmacological agents for OA pain by performing a systematic review of randomized placebo-controlled trials CS (and other 6 commonly used pharmacological agents for OA pain) In total, 14,060 patients in 63 trials were evaluated CS had maximum mean efficacies at 1-4 weeks [80] CS A MEDLINE search was conducted from 1996 through 2007 and five articles reporting results from three trials were identified. One additional trial was identified through review of presentations at annual rheumatology meetings. There was no evidence of heterogeneity across the trials and results were pooled using a fixed effects meta-analysis This analysis demonstrates that CS is effective in reducing the rate of decline in minimum joint space width in patients with OA of the knee. CS may have a role as an S/DMOAD agent in the management of patients with knee OA [81] 2008 A meta-analysis of randomized double-blind placebo-controlled clinical trials to assess the efficacy of CS as an S/DMOAD agent for knee OA has been performed 8 Current Medicinal Chemistry, 2014, Vol. 21, No. 1 Nicola Volpi (Table 3) contd…. Year Study 2008 A MEDLINE database search was conducted for appropriate metaanalyses published between 1997 and 2007 2010 The effect of GlcN, CS, or their combination on joint pain and on radiological progression of disease in OA of the hip or knee was evaluated 2010 2010 2012 This analysis updated a published meta-analysis of double-blind placebo-controlled randomized clinical trials to assess the efficacy of CS as an S/DMOAD for knee OA This study assessed the structural efficacies of daily GlcN and CS in patients with knee OA A meta-analysis of randomized double-blind placebo-controlled clinical trials to assess the efficacy of CS as a SYSADOA in OA of the knee was performed Agent Size Results Reference CS Five meta-analyses that limited their analysis to randomized controlled trials comparing CS with placebo or notreatment control arms have been analyzed Data provided by these metaanalyses indicate that CS has a slight to moderate efficacy in the symptomatic treatment of OA, with an excellent safety profile. [82] CS and GlcN Direct comparisons within trials were combined with indirect evidence from other trials by using a Bayesian model that allowed the synthesis of multiple time points Compared with the placebo, GlcN, CS, and their combination do not reduce joint pain or have an impact on narrowing of joint space [51] CS A published meta-analysis of randomized controlled trials was updated to include data from two new trials published in peer-reviewed literature and limited to randomized clinical trials of 2-year duration. Data were pooled with no evidence of important heterogeneity The results demonstrate that CS is effective in reducing the rate of decline in minimum joint space width in patients with knee OA [83] CS and GlcN Randomized controlled studies on the effects of long-term daily GlcN and CS on joint space narrowing in knee OA patients using MEDLINE and the Cochrane Controlled Trials Register, were evaluated. Meta-analysis was performed using a fixed effect model due to no betweenstudy heterogeneity. Six studies involving 1,502 cases were included This meta-analysis of available data shows that GlcN and CS may delay radiological progression of OA of the knee after daily administration for over 2 or 3 years [84] CS is effective on symptoms A MEDLINE search was in patients with OA of the conducted up to October 2010 knee compared to the plaand two articles reporting two cebo, and may therefore have trials were identified. There was no evidence of heteroge- a role in the management of patients with knee OA of neity across the trials and Kellgren-Lawrence grades II results were pooled using a and III fixed effects model [85] CS nucleus, NF-B enhances the transcription activity of a variety of genes encoding chemokines, cytokines, adhesion molecules, inflammatory-associated enzymes and inhibitors of apoptosis [64]. Furthermore, NF-B is involved in lymphopoiesis and in the differentiation and activation of macrophages, osteoclasts, dendritic cells and granulocytes [65]. As explained above, the NF-B signaling pathway is strictly related to the regulation of inflammatory responses and survival of immune cells. As a consequence, the ability of CS and oligosaccharides derived from it to interact with TLR1-13 [66, 67] and CD44 strongly supports its ability to reduce inflammatory responses. In addition, CS contributes to maintaining ECM integrity by increasing the expression of TGF-1 and the synthesis of HA and collagen II. Along with its role in inflammation, as discussed above, NF-B is a key signal in many other cellular processes, such as cell proliferation and survival, cellular stress response, innate immunity and inflammation, related to the development of different human diseases [68]. The paramount im- Condrosulf® Current Medicinal Chemistry, 2014, Vol. 21, No. 1 9 Fig. (2). Schematic representation of the process occurring during joint osteoarthritis progression. Published with permission from [61]. portance of NF-B in inflammatory responses raises the possibility that CS might also be effective in other chronic inflammatory processes or diseases deriving from autoimmune responses (Fig. 4). Fig. (3). Schematic representation of the capacity of chondroitin sulfate (CS) to reduce the nuclear translocation of NF-B or p50/p65 heterodimer by inhibiting reactive oxygen species and/or the extracellular signal-regulated kinase 1/2 (Erk1/2) and p38 mitogen-activated protein kinase (p38MAPK). As a consequence, CS is able to decrease the synthesis of proteolytic enzymes (matrix metalloproteases, MMP-3, -9, -13 and cathepsine B), of proinflammatory enzymes (such as phospholipase A2, PLA2, cyclooxygenase-2, COX-2, and nitric oxide synthase-2, NOS-2), and of pro-inflammatory cytokines (TNF- and IL-1). Published with permission from [60]. Besides studies at molecular and cellular levels and clinical trials, animal models have been extensively applied for the evaluation of CS (and Condrosulf®) activity. Adjuvant arthritis and CIA animal models have been extensively used to evaluate CS efficacy (Table 4). For example, Bauerova et al. [69] described the effect of two different doses of orally administered Condrosulf®, 300 or 900 mg/kg daily, in an adjuvant arthritis animal model. Condrosulf® was able to significantly reduce the extent of arthritis and the consequences occurring in this chronic inflammatory processes, in particular the oxidative stress. The anti-arthritic effect was confirmed by the capacity of Condrosulf® to improve the total antioxidant status, GGT activity, and to reduce the production of pro-inflammatory cytokines, CRP in plasma, phagocytic activity and the intracellular oxidative burst of neutrophils. Fig. (4). Possible beneficial roles of chondroitin sulfate (CS) in multiple autoimmune diseases. CS may act by inhibiting the nuclear translocation of the nuclear factor-B (NF-B), and consequently, the synthesis of pro-inflammatory cytokines, such as TNF- and IL-1, and of pro-inflammatory enzymes, such as cyclooxygenase2 (COX-2) and phospholipase A2 (PLA2). Published with permission from [60]. CONCLUSIONS AND FUTURE PERSPECTIVES On the basis of the above reported trials, Condrosulf® is a structure-modifying agent which has proven efficacy in the symptomatic treatment of knee, hand and hip OA. Moreover, some meta-analyses of placebo-controlled, randomized trials in knee OA patients have assessed the efficacy of Condrosulf® (and CS) in relieving joint pain along with excellent tolerability and no serious adverse events. 10 Current Medicinal Chemistry, 2014, Vol. 21, No. 1 Table 4. Nicola Volpi Animal Models and Related Biological Effects of Orally Administered Condrosulf®/Chondroitin Sulfate (CS) Year Animal Model Biological Effects Reference 1993 Adjuvant arthritis Inhibition of induced arthritis [86] 1998 Chymopapain-induced cartilage degradation Significantly higher cartilage PG content in CS treated animals. Protective effect on the damaged cartilage [87] 2000 Type II collagen induced arthritis Reduction of arthritis index and serum anti-collagen II antibody titer in a dose-dependent manner. Significant inhibition of hind paw edema, synovitis and destruction of the articular cartilage [88] 2004 Type II collagen induced arthritis Significant reduction of hind paw edema, anti-type II collagen antibody and TNF-alpha [89] 2008 Atherosclerosis aggravated by chronic-antigen-induced arthritis CS administration reduced CRP and IL-6. CS administration reduced the nuclear translocation of NF-kB [90] Adjuvant arthritis CS reduced the severity of arthritis and oxidative stress. CS improved total antioxidant status and GGT activity. CS reduced the production of proinflammatory cytokines, CRP, phagocytic activity and the intracellular oxidative burst of neutrophils [69] 2011 Clinical trials and studies on Condrosulf® have been performed using a highly pure active drug, CS, having specific physico-chemical properties as approved by the various National Institutes of Health [70-72]. This is very important considering that specific CS activities strictly depend on its purity, structural characteristics and properties. Moreover, CS is orally administered and different pharmacokinetic and bioavailability parameters may change depending on its structure and origin [17, 18, 73]. On these basis, CS of low quality for content and properties would be unable to have paragonable pharmacological effects compared to pharmaceutical grade CS. Finally, the same clinical efficacy would not be obtained unless different CS preparations had a comparable purity and structural characteristics. Related to this, Condrosulf® having a standardized structure and composed of a highly purified CS not less than 95%, was used to assess the long-term combined S/MOAD effect [43]. degradation associated with arthritic/OA disease. Condrosulf® (and CS in general) beneficial properties may be further improved with the "design" and development of new drugs possessing different and peculiar structures and characteristics. Moreover, new targets to treat inflammation state derived from arthritis/OA condition, as well as to potentially retard the cartilage matrix degeneration, should be evaluated as potential future CS applications. New outcome measures and novel biomarkers will probably yield important advances in the area of SYSADOA and S/DMOAD as well as in that of the degree of disease of different joint structures affected by OA. In fact biomarkers may allow sensitive and specific quantification of disease processes in the different structures of the joint to tailor CS treatment to the target tissue. A future challenge would prove the capacity of biomarkers to predict OA in the asymptomatic patient, as this would allow selection of appropriate patients to receive early CS treatment to obtain maximum benefit. As a consequence, an important step towards future research with CS (and Condrosulf®) would be the identification of groups of patients showing similar features of the disease, in order to establish a more appropriate relationship between the severity of the pathology and therapy. ABBREVIATIONS Many studies on CS mechanism of action indicate that it might reduce the inflammatory state and consequent tissue CONFLICT OF INTEREST The author(s) confirm that this article content has no conflicts of interest. ACKNOWLEDGEMENTS Declared none. CIA = Collagen-induced arthritis CRP = C-reactive protein CS = Chondroitin sulfate ECM = Extracellular matrix EULAR = European League Against Rheumatism GAG(s) = Glycosaminoglycan(s) GAIT = Glucosamine/chondroitin Arthritis Intervention Trial GalNAc = N-acetyl-galactosamine GGT = -glutamyltransferase GlcA = D-glucuronic acid GlcN = Glucosamine Condrosulf® Current Medicinal Chemistry, 2014, Vol. 21, No. 1 KS = Keratan sulfate [18] NF-B = Nuclear factor kappa-light-chain-enhancer of activated B cells [19] NSAID = Non-steroidal anti-inflammatory drug OA = Osteoarthritis OARSI = Osteoarthritis Research Society International PG = Proteoglycan PRR = Pattern-recognition receptor [20] [21] [22] S/DMOAD = Structure/disease arthritis drug modifying anti-osteo [23] SYSADOA = Symptomatic slow acting drug for osteoarthritis [24] REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] Egea; J.; García; A.G.; Verges, J.; Montell, E.; López, M.G. 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