Download Microbial Cell Wall Oligomannan Inhibits

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Antibody Fc portions can interact with cell surface proteins termed Fc
receptors (FcRs). We have examined the expression of FcRs on cultured
human mesangial cells (HMCs) as these receptors may be involved in the
modulation of glomerular inflammation.
IgAtontaining immune complexes are deposited in the mesangium
in IgA nephropathy (IgAN). Fc alpha RI (CD89) has been implicated in
the pathogenesis of IgAN and cultured HMCs are reported to bind IgA.
However, whether HMCs express CD89 is controversial. Here, expression
of CD89 was examined using RT-PCR and western blotting. CD89 was
not detected either on rating HMCs or following stimulation of HMCs
with IL-I and TNFa or with dibutyrl cyclic AMP (dbcAMP).
A novel FcR, which binds IgA and IgM, was recently described on
murine macrophages and B lymphocytes. We detected RNA transcripts
for the human homologue of this Fc alphdmu receptor in all of 6 HMC
lines examined. Expression was upregulated following stimulation with
IL-l and TNFa. This new IgA binding receptor may be involved in the
pathogenesis of IgAN.
The presence of Fc receptors for IgG was examined using RT-PCR.
Transcripts for the high affinity receptor CD64, and the various forms of
the low affinity receptors, CD32 and CD16, were not detected on any
HMCs. Expression was not induced following stimulation of HMCs with
either IL-1 and TNFa or with dbcAMP. The Fc gamma chain, an
accessory molecule required for expression and signal transduction by
several FcRs was not detected either.
In summary, HMCs were found to express transcripts only for a
novel IgNIgM FcR. This receptor is upregulated by inflammatory
cytokines and may be responsible for glomerular IgA immune complex
deposition in IgA nephropathy.
M2 I
PLASMA OUABAIN LIKE SUBSTANCEAND
PLATELET SODIUM PUMP ACTIVITY IN CHRONIC
RENAL FAILURE
9P
M22MICROBIAL CELL WALL OLIGOMANNAN INHIBITS
NEUTROPHIL CHEMILUMINESCENCE: A POSSIBLE
MECHANISM FOR GRANULOMA FORMATION IN
CROHN'S DISEASE?
C M MPOFU, JM MODES, and SW EDWARDS
Department of Medicine and School of Biological Sciences,
University of Liverpool, Liverpool L69 3GA
Background crohn's l i e intestid lesions OCCUT in Chronic ~ u l o m a t t w s
Disease, a condition caused by a defea in phagacyte fimction. C r o b disease
patients commonly have serum antibcdies to baker's yeast (Socchmmyces
cerevrsiw). The epitope for this antibody is oligomannan which is present in
t m e r i a l and yeast cell walls. Our hypothesis is that oligomannan, shed by
intramud bacteria, may inhibit neU(r0phil function within the mucosa,
leading to the granulomatous lesions seen in CD.Methods The effect of S.
cerevesiae oligomannan on phorbol ester @MA) induced-rrspiratoryburst of
neutmphils from healthy volunteers was measuTed by luminol-ampliliedor
isoluminol-amplified chemiluminescemz. Neutrophils were isolated using a
onestep o
-n
method and suspended in HBSS buffer R s u ~ .
I
I
Oliomannan decreases the neutrophil
3
0.lZhg
0.25nq
1
0.-
Oligomannan dose (mghl)
At the highnt concenlration used (1 mg/mL), oligomannan idubited luminol
dependent chemiluminescence by 68 % (rt 5 "/4 n = 6). Luminol
chemilumkscence measures the combined activities of the neutrophil NADPH
oxidas and myeloperoxidas, and so the oligomannan could be acring on either
or both of these activities Hower, oligomannan (at 1 mg/mL) also inhibited
PMA-stimulated isolnminol-amplifiedchemilumin-ce
by 54.9% (* 10%).
As isoluminol largely measures superoxide secretion, the oligomannm may
have an effect on NADPH oxidase activity, or scavenge extracellularoxidants.
Concludon S cerevesrue oligomannan causes dose-related inhibition of the
PMA-induced respiratory burst This supports the hypothesis that microbial
oligomannaos impair m u d phagocyte function, thus generating the
granulomatous phenotype of Crohn's disease.
F FONG, A BUTT, D GOLDSMITH and R SWAMINATHAN*
M23 COELIAC DISEASE AND THE CTLA-4/CD28 GENE
Department of Chemical Pathology and Renal Medicine
Guy'and St Thomas' Hospitals Trust
Chronic renal failure (CRF) is associated with reduction in
the activity of Na,K-ATPase. There is a suggestion that this
reduction in activity may, in part, be due to the presence of
endogenous sodium transport inhibitor(s). An example of
one such inhibitor is the recently identified ouabain-like
substance (OLS). Using a ouabain radioimmunoassay, we
have previously shown that serum and urine OLS increase on
sodium loading. In the present study the relationship
between serum OLS and platelet Na', K'-ATPase activity
was investigated. Five groups of subjects comprising (A)
healthy individuals (n=ll), (B) CRF patients on dialysis
@=lo), (C) patients on haemodialysis (n=lO), @) peritoneal
dialysis (CAPD, n=14) and (E) patients after renal transplant
(n=15) were examined. Subjects were well matched for
relevant clinical parameters (e.g. age, sex, BMI and plasma
sodium concentration), with the exception of groups D
(range 39 - 76 years) and E (range 38 - 81 years) who were
significantly older group A (range 21 - 56 years). Platelet
Na', K' ATPase activity was lower (51.7* 6.8 Wgpr) and
plasma OLS (0.35* 0.03 nmol/L) was higher in group C
compared to that in group A ( 7 3 3 5.2 U/gpr, 0.26* 0.05
nmovL). Platelet Na', K'-ATPase activity showed a strong
and significant inverse correlation with plasma OLS
concentration (r = -0.855, p < 0.05). Surprisingly, Na', K'ATPase activity remained depressed and OLS increased
significantly after 4 hours of haemodialysis, whereas the
converse may have been expected. The results suggest that
the reduction in sodium pump activity is associated with high
OLS.
REGION: EVIDENCE FOR ASSOCIATION IN UK FAMILIES
AL KING, SJ MOODIE, JS FRASER, D CURTIS, E REID, AM
DEARLOVE, and PJ CICLITIRA'
GastroenterologyUnit, GKT, The Rayne Institute, St Thomas'
Hospital, London SEI 7EH
Background Susceptibilityto coeliac disease (CD) has a strong genetic
component, with a known association with certain HLA-DQ alleles.
However this accounts for only a proportion of the heritability, and it is
likely that other non-HLA genes are involved in disease development.
Association of CD with a locus on chromosome 2q33, which contains the
cytotoxic T-lymphocyte associated (CTLA-4)gene and the CD28 gene has
been demonstrated in a number of European populations, but not in others.
Aim Our aim was to investigate this gene region in UK coeliac families
using an association study design.
Methods We genotyped 166 families for 6 microsatellitemarkers spanning
3cM of the CTLA-4/CD28 gene region. One hundred and forty-two ofthese
families were also genotyped for 2 single nucleotide polymorphisms (SNPs)
in the CTLA-4 gene, one at position +49 (A/G)in exon I, and the other at
position -3 18(CTT), in the promoter region. Data for biallelic markers were
analysed using the transmission disequillibriumtest (TDT).Multiallelic data
were analysed using the ETDT program, which carries out a logistic
regression analysis to determine whether different marker alleles vary in
terms of their probability for being transmitted from a heterozygous parent to
an affected offspring.
Results The SNPs showed no evidence of association,and these two
polymorphisms are unlikely to account for disease susceptibility. There was,
however, significant evidence for associationbetween CD and the D2S2214
microsatellite marker (x2=19.4,7df, p=0.007).The major contributionto
this associationwas made by allele *278,which was transmitted from 92
heterozygous parents and not transmitted from 49 (x2 =I 3. I , 1 df, p=0.0003).
Conclusion The results support the findings of other European studies, and
suggest that an important non-HLA susceptibility locus lies within this
region.