The autoimmune model of schizophrenia

Schizophrenia is of mysterious causation. It is not infectious, not congenital, but shows familial aggregation, the Mendelian genetics indicating involvement of multiple codominant genes with incomplete penetrance. This is the pattern for autoimmune diseases, such as Graves' disease of the thyroid, where forbidden clones of B lymphocytes develop, and cause thyrotoxicosis by secreting autoantibodies that react with the thyroid gland's receptor for thyroid-stimulating hormone from the pituitary gland. In 1982, Knight postulated that autoantibodies affecting the function of neurons in the limbic region of the brain are a possible cause of schizophrenia. Today, this is even more probable, with genes predisposing to schizophrenia having being found to be immune response genes, one in the MHC and two for antibody light chain V genes. Immune response genes govern the immune repertoire, dictating the genetic risk of autoimmune diseases. The simplest test for an autoimmune basis of schizophrenia would be trial of immunosuppression with prednisone in acute cases. The urgent research need is to find the microbial trigger, as done by Ebringer for rheumatoid arthritis and for ankylosing spondylitis. This could lead to prophylaxis of schizophrenia by vaccination against the triggering microbe.

Rheumatoid arthritis patients have elevated antibodies to cross-reactive and non cross-reactive antigens from Proteus microbes

BACKGROUND AND OBJECTIVE

Although a large number of independent studies have shown a paramount role for Proteus mirabilis in the aetiopathogenesis of rheumatoid arthritis (RA), this hypothesis is still controversial among rheumatologists. The main obstacle to its acceptance is the impression that increased Proteus antibodies in RA patients is a secondary phenomenon, occurring as the result of cross-reactivity between bacterial and self-antigens. To shed light on this problem, we examined the link between antibodies to various cross-reactive and non cross-reactive antigenic peptides from P. mirabilis and analysed the relationship between these antibodies and disease severity in patients with RA.

METHODS

Using the ELISA method, serum samples from 70 RA patients and 20 healthy controls were screened for total and class-specific antibodies against three human cross-reactive and non-crossreactive synthetic peptides from P. mirabilis haemolysin, urease C and urease F enzymes. An antibody index, which comprised the total concentration of antibodies against these peptides in each sample, was correlated with the biochemical parameters of disease activity and/or severity, such as the erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and rheumatoid factors (RF). Furthermore, anti-peptide antibody indices were evaluated among RA patients with different levels of disease activity as defined by ESR and CRP.

RESULTS

Significantly elevated levels of total and class-specific IgG antibodies against the 3 Proteus peptides were observed among RA patients compared to healthy controls (p < 0.001). Active RA patients had elevated IgM antibodies against all peptides compared to healthy subjects (p < 0.001). However, no such elevation was observed in IgA anti-peptide antibodies in RA patients. A positive correlation was observed between the antibody indices and ESR (p < 0.001) and CRP (p < 0.01) concentrations, but not the RF status or disease duration. Furthermore, more than 90% of active RA patients showed positive values for the Proteus anti-peptide indices.

CONCLUSION

The elevated levels of antibodies against Proteus antigenic epitopes (which are cross-reactive or non cross-reactive with human tissue antigens) observed indicates that this enhanced bacterial immune response in RA patients is specifically triggered by Proteus microbes. Furthermore, the correlation of anti-peptide antibody indices with the biochemical markers of disease activity indicates that these antibodies exert damaging cytotoxic effects on joint tissues during the course of the disease.

Antibacterial and antipeptide antibodies in Japanese and Finnish patients with rheumatoid arthritis

It has been suggested that Proteus infection may be involved in the pathogenesis of rheumatoid arthritis (RA). Bacterial and peptide immune responses in patients with RA and other control subjects were investigated in two geographically different populations. Serum samples from Finnish patients with early ( n=72) and advanced ( n=27) RA and 30 Finnish healthy controls, as well as from Japanese RA patients from two different locations: Tokyo ( n=30) and Otsu ( n=30), 18 patients with systemic lupus erythematosus (SLE) and 23 Japanese healthy controls were all screened for the total, and class-specific (IgG, IgA and IgM) antibodies against Proteus mirabilis, Escherichia coli and Serratia marcescens by indirect immunofluorescence assay. These samples were also tested for the determination of levels of isotypic antibodies against the shared epitope involving 16-mer synthetic peptides containing the EQRRAA or ESSRAL sequences and compared to scrambled control peptide by using an enzyme-labeled immunosorbent assay method. Significantly elevated levels of IgG and IgM antibodies to P. mirabilis and antibodies against both EQRRAA and ESSRAL peptides were detected in sera of Finnish patients with early and advanced RA, and in Japanese patients from Otsu or Tokyo compared to their corresponding control groups. In contrast, no difference either in the total or in any of the isotypic antibodies were observed between these groups when serum samples were screened against each of E. coli and S. marcescens or against the control peptide. Furthermore, there was a significant correlation between the antibody levels against Proteus bacteria only and both EQRRAA and ESRRAL peptides. Our findings support the possibility for specific involvement of P. mirabilis in the etiopathogenesis of RA even in early cases.

Cross-reactivity between related sequences found in Acinetobacter sp., Pseudomonas aeruginosa, myelin basic protein and myelin oligodendrocyte glycoprotein in multiple sclerosis

To investigate the possible role of molecular mimicry to bacterial components in multiple sclerosis (MS) pathogenesis we examined antibody responses to mimicry peptide sequences of Acinetobacter, Pseudomonas aeruginosa and myelin components. Antibodies to mimicry peptides from Acinetobacter (p<0.001), P. aeruginosa (p<0.001), myelin basic protein (MBP) (p<0.001) and myelin oligodendrocyte glycoprotein (MOG) (p<0.001) were significantly elevated in MS patients compared to controls. Antisera against MBP (residues 110-124) reacted with both Acinetobacter and Pseudomonas peptides from 4- and gamma-carboxymuconolactone decarboxylase, respectively. MOG (residues 43-57) antisera reacted with Acinetobacter peptide from 3-oxo-adipate-CoA-transferase subunit A. The role of these bacteria in MS is unclear but demonstrates that molecular mimicry is not restricted to viruses suggesting bacterial infections could play a role in MS pathogenesis. Further work is required to evaluate the relevance of these cross-reactive antibodies to the neuropathology of MS.

Antibodies to prion and Acinetobacter peptide sequences in bovine spongiform encephalopathy

An amino acid sequence homology has been identified between the bovine prion sequence (RPVDQ) and the Acinetobacter calcoaceticus enzyme, uridine-diphosphate-N-acetyl glucosamine-1-carboxy-vinyl-transferase which also contains (RPVDQ). Class-specific IgA, IgG and IgM antibodies against synthetic peptides containing the structurally related sequences present in bovine prion and A. calcoaceticus were measured in 189 bovine spongiform encephalopathy (BSE) positive cattle, 127 BSE negative cattle and 87 healthy control animals using an ELISA technique. Class-specific IgA, IgG and IgM antibodies against the structurally related synthetic peptides were significantly elevated in BSE positive cattle when compared to BSE negative cattle (P < 0.001) and healthy control animals (P < 0.001). These autoantibodies may have a role in the pathogenesis of BSE.

Antibodies to Acinetobacter bacteria and bovine brain peptides, measured in bovine spongiform encephalopathy (BSE) in an attempt to develop an ante-mortem test

Bovine spongiform encephalopathy (BSE) is a neurological disease of cattle. Antibody responses to Acinetobacter radioresistens and six other bacteria, as well as to bovine myelin basic protein and bovine neurofilaments were measured in 128 BSE positive animals, 63 BSE negative animals and 64 healthy control animals. Animals positive for BSE had the highest levels of antibodies to Acinetobacter radioresistens (p < 0.0001) and also autoantibodies to bovine myelin basic protein (p < 0.0001) and bovine neurofilaments (p < 0.0001). In an endeavour to develop an antemortem test for BSE, 12 different strains of Acinetobacter were further tested in a MAN (myelin-Acinetobacter-neurofilament) assay involving 28 BSE positive and 18 BSE negative animals and defined bovine brain peptides. Five out of the 12 Acinetobacter bacteria tested [Acinetobacter (sp3), A. haemolyticus (sp4), A. johnsonii (sp7), A. lwoffii (sp8) and Acinetobacter (sp9)] gave 100% sensitivity and 100% specificity for detecting BSE. The highest anti-bacterial antibody level compared to controls was obtained with A. johnsonii. Further field studies are required to determine the validity of the MAN assay in detecting animals affected with BSE.

Antibody responses to Acinetobacter spp. and Pseudomonas aeruginosa in multiple sclerosis: prospects for diagnosis using the myelin-acinetobacter-neurofilament antibody index

Antibody responses to Acinetobacter (five strains), Pseudomonas aeruginosa, Escherichia coli, myelin basic protein (MBP), and neurofilaments were measured in sera from 26 multiple sclerosis (MS) patients, 20 patients with cerebrovascular accidents (CVA), 10 patients with viral encephalitis, and 25 healthy blood donors. In MS patients, elevated levels of antibodies against all strains of Acinetobacter tested were present, as well as antibodies against P. aeruginosa, MBP, and neurofilaments, but not antibodies to E. coli, compared to the CVA group and controls. The myelin-Acinetobacter-neurofilament antibody index appears to distinguish MS patients from patients with CVAs or healthy controls. The relevance of such antibodies to the neuropathology of MS requires further evaluation.

Proteus IgG antibodies and C-reactive protein in English, Norwegian and Spanish patients with rheumatoid arthritis

The distribution of Proteus antibody levels was compared in English, Norwegian and Spanish patients with rheumatoid arthritis (RA). Using an indirect immunofluorescence method, the IgG antibody titre against Proteus mirabilis was measured in the sera of 27 English, 53 Norwegian and 34 Spanish patients with RA and divided into active and inactive disease groups according to the serum C-reactive protein (CRP) level (> or = 10 mg/l). Serum samples were also collected from 25 English, 30 Norwegian and 14 Spanish healthy individuals who served as controls. The levels of Proteus IgG antibodies were significantly higher in the sera of active RA patients (p<0.001) when compared with the corresponding healthy controls, whether these groups belonged to the English, Norwegian or Spanish populations. Furthermore, active RA patients from each country showed significantly higher levels of Proteus antibodies when compared with inactive English (p<0.01), Norwegian (p<0.001) or Spanish (p<0.001) RA patients. Finally, a significant correlation was observed between Proteus IgG antibody levels and the CRP concentrations in RA patients whether each population was tested individually or all together (p<0.001). The increased levels of Proteus antibodies in RA patients from three different European countries support the concept of a possible aetiopathogenetic role for Proteus microorganisms in the development of RA.

Correlation between the immune responses to collagens type I, III, IV and V and Klebsiella pneumoniae in patients with Crohn's disease and ankylosing spondylitis

BACKGROUND

Increased levels of collagen types I, III and V are found in strictures of patients with Crohn's disease (CD) compared with normal gut tissue. Type IV collagen is present in the basement membranes, basal lamina, retina and cornea. Elevated levels of antibody to Klebsiella pneumoniae are found in both active CD and active ankylosing spondylitis (AS) patients compared with healthy controls.

METHODS

Reactivities for immunoglobulin class-specific antibodies (IgM, IgG and IgA) against collagen types I, III, IV, V and whole K. pneumoniae were measured by ELISA in nine patients with early CD and 10 with late CD from King's College Hospital and 12 late CD patients and 36 HLA-B27-positive AS patients from Middlesex Hospital and was compared with values for 26 healthy controls from the Blood Transfusion Service in London.

RESULTS

Levels of class-specific IgM, IgG and IgA antibodies to collagen types I, III, IV, V and K. pneumoniae were significantly elevated in early and late CD patients compared with healthy controls (P<0.001). Levels of IgM, IgG antibody to the four collagen types and K. pneumoniae were also significantly elevated (P<0.001) in AS patients compared with healthy controls. In addition, the level of IgA antibody to K. pneumoniae was elevated in AS patients (P<0.001). Furthermore, a positive correlation between antibody levels to collagen types I, III, IV and K. pneumoniae was demonstrated in both early and late CD patients and in those with AS, whilst a positive correlation to type V was found in early CD.

CONCLUSION

The role of K. pneumoniae and anti-collagen antibodies in the aetiopathogenesis of CD and AS requires further study.

Genetic diversity in Proteus mirabilis isolates found in the urinary tract of rheumatoid arthritis patients

OBJECTIVE

Elevated levels of anti-Proteus antibodies but not antibodies to E. coli have been reported in patients with rheumatoid arthritis (RA). The suggestion has been made that P. mirabilis may have a role in the aetiopathogenesis of rheumatoid arthritis. The aim of this study was to determine whether there are differences at the genetic level inisolates of P. mirabilis obtained from controls and RA patients.

METHODS

A blind study was performed whereby P. mirabilis isolates obtained from urinary cultures of RA patients and controls were analysed using RAPD PCR. Isolates were then grouped on the basis of their DNA band profile after agarose gel electrophoresis, thereby allowing the composition of the Proteus population in the urinary tract to be analysed at the genetic level.

RESULTS

Fourteen different DNA band profiles were obtained from the 93 isolates tested: 70% of these isolates fell into only five of the 14 groups and approximately 25% of all isolates fell into one group. No differences were observed in the frequency of isolates from either control or RA subjects.

CONCLUSIONS

There is genetic diversity in P. mirabilis populations found in the urinary tract, but there are no differences in the frequency of these bacteria between RA patients and controls.

Molecular mimicry between HLA-DR alleles associated with rheumatoid arthritis and Proteus mirabilis as the Aetiological basis for autoimmunity

Molecular mimicry is one of the pathological mechanisms proposed to explain the association between microorganisms and autoimmune diseases. This review deals with the association between bacteria and rheumatic diseases with a special emphasis on rheumatoid arthritis where upper urinary tract infection by Proteus mirabilis is the possible cause of this severe, arthritic condition. Prospective trials involving anti-Proteus therapy should be carried out.

Polymorphisms of the CYP2D6 gene increase susceptibility to ankylosing spondylitis

Ankylosing spondylitis (AS) is a common and highly familial rheumatic disorder. The sibling recurrence risk ratio for the disease is 63 and heritability assessed in twins >90%. Although MHC genes, including HLA-B27, contribute only 20-50% of the genetic risk for the disease, no non-MHC gene has yet been convincingly demonstrated to influence either susceptibility to the disease or its phenotypic expression. Previous linkage and association studies have suggested the presence of a susceptibility gene for AS close to, or within, the cytochrome P450 2D6 gene (CYP2D6, debrisoquine hydroxylase) located at chromosome 22q13.1. We performed a linkage study of chromosome 22 in 200 families with AS affected sibling-pairs. Association of alleles of the CYP2D6 gene was examined by both case-control and within-family means. For case-control studies, 617 unrelated individuals with AS (361 probands from sibling-pair and parent-case trio families and 256 unrelated non-familial sporadic cases) and 402 healthy ethnically matched controls were employed. For within-family association studies, 361 families including 161 parent-case trios and 200 affected sibling-pair families were employed. Homozygosity for poor metabolizer alleles was found to be associated with AS. Heterozygosity for the most frequent poor metabolizer allele (CYP2D6*4) was not associated with increased susceptibility to AS. Significant within-family association of CYP2D6*4 alleles and AS was demonstrated. Weak linkage was also demonstrated between CYP2D6 and AS. We postulate that altered metabolism of a natural toxin or antigen by the CYP2D6 gene may increase susceptibility to AS.

HLA molecules, bacteria and autoimmunity

It has been well established that many diseases are linked to HLA antigens. Two of the most interesting HLA associations may provide some insight into the pathogenesis of rheumatic inflammatory conditions. In ankylosing spondylitis (AS), 96% of patients possess HLA-B27, whilst the frequency of this marker in the general population is c. 8%. In rheumatoid arthritis (RA), >90% of patients possess either HLA-DR1 or some subtypes of HLA-DR4, whilst the frequency of this marker in the general population is c. 35%. The association between HLA-B27 and reactive arthritis (ReA) has also been well established. Furthermore, it has been shown that ReA is triggered by infection via the gastrointestinal tract due to Yersinia, Salmonella or Campylobacter spp. and in the genitourinary tract due to chlamydia. In a similar way, microbiological and immunological studies have revealed an association between Klebsiella pneumoniae in AS and Proteus mirabilis in RA. This article reviews the possible pathological implications of the associations between HLA-B27, K. pneumoniae and AS, as well as HLA-DR1/DR4, P. mirabilis and RA.

Autoantibodies to brain components and antibodies to Acinetobacter calcoaceticus are present in bovine spongiform encephalopathy

Bovine spongiform encephalopathy (BSE) is a neurological disorder, predominantly of British cattle, which belongs to the group of transmissible spongiform encephalopathies together with Creutzfeldt-Jakob disease (CJD), kuru, and scrapie. Autoantibodies to brain neurofilaments have been previously described in patients with CJD and kuru and in sheep affected by scrapie. Spongiform-like changes have also been observed in chronic experimental allergic encephalomyelitis, at least in rabbits and guinea pigs, and in these conditions autoantibodies to myelin occur. We report here that animals with BSE have elevated levels of immunoglobulin A autoantibodies to brain components, i.e., neurofilaments (P < 0.001) and myelin (P < 0.001), as well as to Acinetobacter calcoaceticus (P < 0.001), saprophytic microbes found in soil which have sequences cross-reacting with bovine neurofilaments and myelin, but there were no antibody elevations against Agrobacterium tumefaciens or Escherichia coli. The relevance of such mucosal autoantibodies or antibacterial antibodies to the pathology of BSE and its possible link to prions requires further evaluation.

Cross-reactivity between the rheumatoid arthritis-associated motif EQKRAA and structurally related sequences found in Proteus mirabilis

Cross-reactivity or molecular mimicry may be one of the underlying mechanisms involved in the etiopathogenesis of rheumatoid arthritis (RA). Antiserum against the RA susceptibility sequence EQKRAA was shown to bind to a similar peptide ESRRAL present in the hemolysin of the gram-negative bacterium Proteus mirabilis, and an anti-ESRRAL serum reacted with EQKRAA. There was no reactivity with either anti-EQKRAA or anti-ESRRAL to a peptide containing the EDERAA sequence which is present in HLA-DRB1*0402, an allele not associated with RA. Furthermore, the EQKRAA and ESRRAL antisera bound to a mouse fibroblast transfectant cell line (Dap.3) expressing HLA-DRB1*0401 but not to DRB1*0402. However, peptide sequences structurally related to the RA susceptibility motif LEIEKDFTTYGEE (P. mirabilis urease), VEIRAEGNRFTY (collagen type II) and DELSPETSPYVKE (collagen type XI) did not bind significantly to cell lines expressing HLA-DRB1*0401 or HLA-DRB1*0402 compared to the control peptide YASGASGASGAS. It is suggested here that molecular mimicry between HLA alleles associated with RA and P. mirabilis may be relevant in the etiopathogenesis of the disease.

Antibodies to Klebsiella pneumoniae lipopolysaccharide in patients with ankylosing spondylitis

The role of microbial lipopolysaccharides (LPS) in the aetiopathogenesis of ankylosing spondylitis (AS) is a matter of continuing debate. In this study, class-specific IgG, IgA and IgM antibodies against Klebsiella pneumoniae, Escherichia coli, Salmonella typhimurium and Salmonella enteritidis LPS were measured by enzyme-linked immunosorbent assay (ELISA) in 100 AS patients, 50 rheumatoid arthritis (RA) patients and 50 healthy control subjects. The AS patients had significantly elevated levels of IgG and IgA antibodies against K. pneumoniae LPS (P < 0.001) and IgA antibodies against E. coli LPS (P < 0.05) compared to healthy controls. There were no significant elevations of antibody levels against S. typhimurium and S. enteritidis in the three study groups. In addition, there was a correlation between IgG and IgA anti-K. pneumoniae LPS antibody levels and the acute-phase reactant C-reactive protein (P < 0.001).

Antibiotic sensitivity and proticine typing of Proteus mirabilis strains associated with rheumatoid arthritis

Urinary isolates of Proteus mirabilis, obtained from 49 RA patients and 44 healthy controls, were tested for susceptibility to antibiotics by the disc diffusion method. In addition, P. mirabilis isolates were also tested for proticine production and sensitivity (p/s) typing by the inhibition of growth of each test isolate against 13 reference strains of P. mirabilis. The P. mirabilis isolates from both RA patients and healthy controls were highly susceptible to norfloxacin, ciprofloxacin and trimethoprim, but less to minocycline. The urine of RA patients contained fewer different types of P. mirabilis strains than those isolated from healthy controls. All of the strains found in the RA patients were proticine producers (P < 0.001), mostly of proticine 3 (P < 0.005). The presence of such strains provides evidence of a sub-clinical upper urinary tract infection with P. mirabilis in some RA patients. Therapeutic intervention in RA with relevant antibiotics requires evaluation.

Characterization of the humoral immune response to Klebsiella species in inflammatory bowel disease and ankylosing spondylitis

This study was carried out to characterize the antibody class response by ELISA to seven Klebsiella pneumoniae serotypes (K2, K3, K17, K21, K26, K36, K50) in five different groups, 40 HLA-B27-positive ankylosing spondylitis (AS) patients, 46 patients with Crohn's disease (CD), 38 patients with ulcerative colitis (UC), 50 patients with active anti-endomysial antibody-positive coeliac disease and 40 healthy controls, using whole bacteria and capsular polysaccharide. IgG antibody levels were significantly elevated in AS patients to K17, K36, K50; IgA to K2, K3, K21, K26, K36 and K50; and IgM to serotype K21 when compared to normal controls. Furthermore, IgG antibody levels were significantly elevated in CD patients to K2, K17, K21, K26, K36 and K50; IgA to K2, K3, K21, K26, K36 and K50; and IgM to K2, K3, K17, K21 and K50. Increased IgG antibody levels in the UC group were limited only to K17, K36 and K50. No antibody class was increased to any of the K. pneumoniae serotypes in the coeliac disease group. The immune responses in AS patients also involve Klebsiella bacteria having capsular serotypes other than K26, K36 and K50. The similarity in the immune responses between CD and AS groups suggests that many AS patients may have occult bowel inflammation.

Antibodies to Klebsiella pneumoniae in Dutch patients with ankylosing spondylitis and acute anterior uveitis and to Proteus mirabilis in rheumatoid arthritis

OBJECTIVE

To determine whether the association between increased humoral reactivity against Klebsiella and HLA-B27 associated diseases could be confirmed in Dutch patients with ankylosing spondylitis (AS) and acute anterior uveitis (AAU).

METHODS

Under coded conditions sera from Dutch patients with AS, AAU, and rheumatoid arthritis (RA) and from HLA-B27 positive and negative healthy controls were studied for IgA anti-Klebsiella (K54) and IgG anti-Proteus antibodies with the indirect immunofluorescence assay on whole bacteria fixed in suspension with paraformaldehyde. Each group consisted of at least 17 sera.

RESULTS

IgA anti-Klebsiella antibody titers were elevated in AS and HLA-B27 negative AAU compared to the HLA-B27 positive and negative controls or patients with active RA (p < 0.001). Furthermore, patients with active RA had elevated levels of IgG antibodies against P. mirabilis compared to every other test or control group (p < 0.001). There was no significant difference between the AS and RA patients in terms of serum C-reactive protein levels, although these were significantly elevated in both compared to healthy controls (p < 0.001), suggesting that the antibody elevations were not due to a nonspecific inflammatory effect. The same sera were blindly tested with negative results by 2 other centers. The discrepancies are probably the result of differences in the methods used.

CONCLUSION

Our data support the hypothesis that Klebsiella are involved in the pathogenesis of AS and AAU and that the same might be true for Proteus in RA.

Bovine spongiform encephalopathy: is it an autoimmune disease due to bacteria showing molecular mimicry with brain antigens?

Bovine spongiform encephalopathy (BSE) could be an autoimmune disease produced following exposure of cattle to feedstuffs containing bacteria showing molecular mimicry between bacterial components and bovine tissue. Analysis of molecular sequence databases (Genbank and SwissProt) shows that three bacteria (Acinetobacter calcoaceticus,Ruminococcus albus, and Agrobacter tumefaciens) share sequences with the encephalitogenic peptide of bovine myelin, while three molecules in Escherichia coli show molecular mimicry with host-encoded prion protein. Immune responses against these bacteria at both T and B cell levels may cause neurological tissue injury resembling BSE. The role of these bacteria in BSE, if any, merits further investigation.

Antibodies to Klebsiella, Proteus, and HLA-B27 peptides in Japanese patients with ankylosing spondylitis and rheumatoid arthritis

OBJECTIVE

To determine whether patients with ankylosing spondylitis (AS) and patients with rheumatoid arthritis (RA) from Japan have antibodies to Klebsiella pneumoniae and Proteus mirabilis and to assess whether such antibodies are activated against peptides sharing sequences with HLA-B27.

METHODS

Serum samples from 152 Japanese patients, 52 with AS, 50 with RA, and 50 healthy controls, were tested against 3 bacteria (K. pneumoniae, P. mirabilis, and Escherichia coli) and 3 synthetic peptides (HLA-B27, pullulanase-D, and scrambled pullulanase-D control peptide) by ELISA under coded conditions. Samples were tested for elevations in IgG, IgA, and IgM antibody classes in patients with active AS or RA, in patients with RA with probable disease, and in patients with inactive AS. Disease activity was determined by an elevated serum C-reactive protein (> 10 mg/l) level and elevated erythrocyte sedimentation rate (> 20 mm/h).

RESULTS

Patients with active AS showed specific elevations in serum IgA antibody levels against K. pneumoniae compared to patients with RA and controls (p < 0.001). No such elevation was seen in the IgG and IgM antibody classes. Patients with inactive AS showed no elevation in any class of antibody against K. pneumoniae compared to controls or patients with RA. Patients with active or probably active RA showed significant elevations in IgG antibody levels against P. mirabilis compared to AS and controls (p < 0.001). Patients with AS (active or inactive), RA (active or probably active), and controls showed no elevations in any antibody class to E. coli. Both active and inactive AS patients had specific autoantibodies against HLA-B27 peptide compared to patients with RA and controls (active AS: IgG, IgA, IgM, p < 0.001; inactive AS: IgG and IgA, p < 0.001). Patients with active AS had IgG and IgA antibodies against pullulanase-D peptide, which contains a sequence that cross reacts with HLA-B27 compared to controls (p < 0.001).

CONCLUSION

These results provide the first evidence of AS and RA patients in Japan having specific elevations of antibody to K. pneumoniae and P. mirabilis, respectively. This suggests that K. pneumoniae in AS and P. mirabilis in RA may play a role in triggering and/or exacerbating these diseases.

Correlation between anti-Proteus antibodies and isolation rates of P. mirabilis in rheumatoid arthritis

In a survey of 89 RA patients, carried out under code, Proteus mirabilis was isolated from the urine of 63% (47/75) of female (P < 0.001) and 50% (7/14) of male patients (P < 0.001), compared to a frequency of isolation in healthy women of 32% (38/119) and 11% (13/115) in healthy men. There was no significant difference in isolation rates between 37 non-RA patients and healthy controls. Sera from 20 patients with RA and 20 healthy controls were tested against P. mirabilis and Escherichia coli by an enzyme-linked immunosorbent assay. Antibodies against P. mirabilis but not to E. coli were significantly higher in the RA patients than in healthy controls (P < 0.001). Furthermore, a positive correlation was found between high anti-Proteus antibody levels in serum samples and the number of Proteus colony-forming units obtained from urine specimens of the 20 RA patients (r = +0.714, P < 0.001). These results support the suggestion of an aetiopathogenic role for P. mirabilis in RA.

The genetic and bacteriological aspects of Peyronie's disease

PURPOSE

Peyronie's disease has been associated with HLA tissue types, including HLA-A1, DR3, DQw2 and HLA-B7 cross-reactive group antigens which include HLA-B27. This association was tested as was the process of molecular mimicry where the host HLA surface antigen cross-reacts with a microorganism.

MATERIALS AND METHODS

HLA tissue typing was performed on 51 white patients with Peyronie's disease, of whom 15 also had Dupuytren's contracture of the hand. Fecal, urine and urethral samples were taken from patients with Peyronie's disease who had proved penile inflammation on biopsy. The samples were cultured for species of Campylobacter, Shigella, Salmonella, Yersinia, Chlamydia and gonococcus, all known to cross-react with the HLA-B27 surface antigen. Antibodies to Klebsiella species, Proteus species and Escherichia coli were also assessed in the sera of 65 patients with Peyronie's disease.

RESULTS

A significant association between Peyronie's disease and HLA-B27 was found (p = 0.02). The remaining antigens of the HLA-B7 group were not significantly associated with the disease individually (HLA-B7 p > 0.2, HLA-B22 p > 0.6, HLA-B40 p > 0.7) or as a group (p = 0.69). The previously found associations did not reach significance in this study (HLA-A1 p > 0.5, HLA-B8 p > 0.2, HLA-Cw7 p = 0.1, HLA-DR3 p > 0.4, HLA-DQ2 p > 0.4). Cultures for all enteric and urethral organisms were negative, and patients with Peyronie's disease did not have elevated serum titers of anti Klebsiella, anti Proteus or anti E. coli antibodies.

CONCLUSIONS

Although there is an association between Peyronie's disease and HLA-B27, molecular mimicry does not occur with the organisms tested, and an infectious agent has not been found in this study.

Antibody responses to gut bacteria in ankylosing spondylitis, rheumatoid arthritis, Crohn's disease and ulcerative colitis

Specific immunoreactive anti-Klebsiella antibodies are found in patients with ankylosing spondylitis (AS), a significant proportion of whom have occult inflammatory bowel disease. Molecular mimicry between Klebsiella or other bacterial antigens and HLA-B27 has been suggested in the pathogenesis of AS. The specificity of increased immunoreactivity against Klebsiella remains to be assessed against the abundant anaerobic bacterial flora, present either in healthy controls or in patients with ulcerative colitis (UC) and Crohn's disease (CD). Total immunoglobulin (Ig; IgG, IgA, IgM) immunoreactivity was measured by ELISA against Klebsiella pneumoniae, Proteus mirabilis, Escherichia coli and ten anaerobic isolates of the predominant normal bowel flora in 35 patients with active AS, 60 patients with inflammatory bowel disease (30 CD, 30 UC), 60 patients with active rheumatoid arthritis (RA) and 60 healthy controls. Ig immunoreactivity to K. pneumoniae was significantly elevated in AS (P < 0.001), CD (P < 0.001) and UC (P < 0.001) patients compared with RA patients and healthy controls. Furthermore, Ig immunoreactivity to P. mirabilis was significantly elevated only in RA patients, compared with the other inflammatory groups (P < 0.001) and controls (P < 0.001). There was no significant antibody response against E. coli or the ten obligate anaerobes in any of the test groups. The data suggested an increased immune response to Klebsiella in patients with AS, UC, CD and to Proteus in patients with RA. The specificity of these responses in some patients supported a possible role for enteric Klebsiella in the pathogenesis of AS and Proteus in RA. The role of Klebsiella in inflammatory bowel disease requires further study.

Antibodies to four gram-negative bacteria in rheumatoid arthritis which share sequences with the rheumatoid arthritis susceptibility motif

The bacteria Proteus, Serratia, Escherichia and Pseudomonas possess sequences resembling the rheumatoid arthritis susceptibility sequence EQRRAA, but antibodies were elevated only to Proteus in 66 RA patients (P<0.001) when compared to 61 active ankylosing spondylitis patients and 60 controls.

Molecular mimicry: the geographical distribution of immune responses to Klebsiella in ankylosing spondylitis and its relevance to therapy

The discovery that HLA-B27 is linked to ankylosing spondylitis (AS) and HLA-DR1/DR4 to rheumatoid arthritis (RA) has provided new approaches to the study of the possible causation of these diseases. Several theories have been proposed to explain these associations but only one, namely "molecular mimicry", has provided a specific aetiological agent for each of these diseases. Molecular mimicry between HLA-B27 and two molecules in Klebsiella microbes: nitrogenase and pullulanase D has been reported whilst in Proteus microbes, the haemolysin molecule shows sterochemical similarity to HLA-DR1/DR4. Elevated immune responses to Klebsiella microbes have been demonstrated in AS patients from 10 different countries and this wide geographical distribution suggests that the same aetiological agent is probably acting in producing this condition. Furthermore RA patients show similar immune responses to Proteus microbes. Whether AS or RA are caused by these bacteria can only be resolved by tissue typing all rheumatological patients early, in the course of their disease and then assessing their response to antibiotic chemotherapy in longitudinal studies involving double-blind crossover trials. It is possible that in the future, the course of AS or even RA could be modified by adequate antibiotic chemotherapy or even diets which affect the substrates on which these bacteria grow.

The use of a low starch diet in the treatment of patients suffering from ankylosing spondylitis

The majority of ankylosing spondylitis (AS) patients not only possess HLA-B27, but during active phases of the disease have elevated levels of total serum IgA, suggesting that a microbe from the bowel flora is acting across the gut mucosa. Biochemical studies have revealed that Klebsiella bacteria, not only possess 2 molecules carrying sequences resembling HLA-B27 but increased quantities of such microbes are found in fecal samples obtained from AS patients and such patients have Crohn's like lesions in the ileo-caecal regions of the gut. Furthermore AS patients from 10 different countries have been found to have elevated levels of specific antibodies against Klebsiella bacteria. It has been suggested that these Klebsiella microbes, found in the bowel flora, might be the trigger factors in this disease and therefore reduction in the size of the bowel flora could be of benefit in the treatment of AS patients. Microbes from the bowel flora depend on dietary starch for their growth and therefore a reduction in starch intake might be beneficial in AS patients. A "low starch diet" involving a reduced intake of "bread, potatoes, cakes and pasta" has been devised and tested in healthy control subjects and AS patients. The "low starch diet" leads to a reduction of total serum IgA in both healthy controls as well as patients, and furthermore to a decrease in inflammation and symptoms in the AS patients. The role of a "low starch diet" in the management of AS requires further evaluation.

Elevation in anti-Proteus antibodies in patients with rheumatoid arthritis from Bermuda and England

OBJECTIVE

To determine whether patients with rheumatoid arthritis (RA) from Bermuda and England have an increased anti-Proteus antibody titer when compared to healthy Bermudian and English controls, and to ascertain whether any increase in antibody titer is specific by testing 4 other microbes, Escherichia coli and 3 normal anaerobic bowel bacteria.

METHODS

Antibody titers were measured by ELISA and indirect immunofluorescence (IIFA) under coded conditions.

RESULTS

Elevated titers of anti-Proteus antibodies were demonstrated in 34 patients with active RA from Bermuda when compared to 33 healthy Bermudian controls by ELISA (p < 0.001) and IIFA (p < 0.001). An elevation of anti-Proteus antibodies was also observed in 34 patients with RA from England when compared to 30 healthy English controls again by ELISA (p < 0.001). A similar antibody elevation in 31 patients with RA from England was observed when compared to 30 healthy controls when measured by IIFA (p < 0.001). However, there was no significant elevation in antibody titers against E. coli or the 3 normal bowel flora isolates in the patients with RA from both countries compared to their respective controls, when measured by ELISA.

CONCLUSION

A specific elevation in the immune response to Proteus mirabilis has been demonstrated in patients with RA from both Bermuda and England. However, this study cannot distinguish between antibody association with disease per se and association with disease activity. The role of Proteus in RA and the effect of anti-Proteus therapy in patients with RA merits further study.

Molecular mimicry and ankylosing spondylitis: possible role of a novel sequence in pullulanase of Klebsiella pneumoniae

Molecular mimicry has been shown between two sequences of Klebsiella pneumoniae pulD secretion protein (DRDE) with HLA-B27 (DRED) and pulA (pullulanase) enzyme (Gly-X-Pro) with types I, III and IV collagen respectively. IgG antibody levels in AS patients were elevated against 16mer synthetic peptides of HLA-B27 and pulD by enzyme immunosorbent assay (ELISA) compared to controls (P < 0.001). ELISA assays against K. pneumoniae grown in the absence and presence of pullulan demonstrated significant levels of IgA antibody in AS patients compared to controls (P < 0.001). Increased IgA and IgG antibody levels to pulA and types I and IV collagen were observed in AS patients compared to controls (P < 0.001). These observations could be relevant in the sequence of molecular events in AS.

The specificity of the anti-Proteus antibody response in tissue-typed rheumatoid arthritis (RA) patients from Brest

Anti-Proteus mirabilis antibody titres were found to be elevated in 50 active tissue-typed French rheumatoid arthritis (RA) patients from Brest when compared to 49 healthy French controls using enzyme-linked immunosorbent assay (ELISA; P < 0.001) and indirect immunofluorescence assay (IIFA; P < 0.001). However, there was no significant elevation in antibody titres against Escherichia coli or Salmonella typhimurium in the RA patients compared to the controls when measured by ELISA. Serum levels of C-reactive protein (CRP) were also found to be significantly higher in RA patients when compared to healthy control subjects (P < 0.001). These results suggest that P. mirabilis may play an important and specific role in the triggering and persistence of RA.

Decrease in anti-Proteus mirabilis but not anti-Escherichia coli antibody levels in rheumatoid arthritis patients treated with fasting and a one year vegetarian diet

OBJECTIVE

To measure Proteus mirabilis and Escherichia coli antibody levels in patients with rheumatoid arthritis (RA) during treatment by vegetarian diet.

METHODS

Sera were collected from 53 RA patients who took part in a controlled clinical trial of fasting and a one year vegetarian diet. P mirabilis and E coli antibody levels were measured by an indirect immunofluorescence technique and an enzyme immunoassay, respectively.

RESULTS

The patients on the vegetarian diet had a significant reduction in the mean anti-proteus titres at all time points during the study, compared with baseline values (all p < 0.05). No significant change in titre was observed in patients who followed an omnivorous diet. The decrease in anti-proteus titre was greater in the patients who responded well to the vegetarian diet compared with diet non-responders and omnivores. The total IgG concentration and levels of antibody against E coli, however, were almost unchanged in all patient groups during the trial. The decrease from baseline in proteus antibody levels correlated significantly (p < 0.001) with the decrease in a modified Stoke disease activity index.

CONCLUSION

The decrease in P mirabilis antibody levels in the diet responders and the correlation between the decrease in proteus antibody level and decrease in disease activity supports the suggestion of an aetiopathogenetic role for P mirabilis in RA.

Shared amino acid sequences between major histocompatibility complex class II glycoproteins, type XI collagen and Proteus mirabilis in rheumatoid arthritis

OBJECTIVES

To show molecular similarity between two sequences of Proteus mirabilis (haemolysin--ESRRAL; urease--IRRET) with HLA-DR antigens (EQRRAA) which are associated with rheumatoid arthritis (RA) and type XI collagen (LRREI), respectively; and, in patients with RA, to measure levels of antibody against a 16-mer synthetic peptide containing the ESRRAL sequence, and the haemolysin and urease proteins of Proteus mirabilis.

METHODS

The homologous sequences EQRRAA and ESRRAL were modelled with Alchemy III, using the crystalline structure of DRB1*0101 (HLA-DR1). Sera from 40 patients with RA, 30 with ankylosing spondylitis (AS), and 30 controls were tested against synthetic ESRRAL peptide and the haemolysin of Proteus mirabilis by enzyme linked immunosorbent assay. Similar tests were also carried out on sera from 20 patients with RA, 40 with AS, and 15 controls, against Proteus mirabilis urease.

RESULTS

Molecular modelling of the homologous sequences ESRRAL/EQRRAA and IRRET/LRREI showed stereochemical similarities. Antibodies to the 16-mer synthetic peptide containing the ESRRAL sequence, the haemolysin, and urease proteins were significantly increased in RA patients compared with AS patients (p < 0.001) and healthy controls (p < 0.001). No such increases were observed with three control peptides including the EDERAA sequence of DRB1*0402 (HLA-DR4/Dw10), the haemolysin proteins of Streptococcus pyogenes and Vibrio parahaemolyticus, and the urease of Bacillus pasteurii.

CONCLUSION

The additive effect of the immune responses to the two Proteus mirabilis antigens, haemolysin (ESRRAL) and urease (IRRET), could be relevant in the aetiopathogenesis of RA.

Serum IgA anti-Klebsiella antibodies in ankylosing spondylitis patients from Catalonia

IgA antibodies against Klebsiella pneumoniae were measured by immunofluorescence in 84 Catalan patients with ankylosing spondylitis (AS), 41 patients with non-inflammatory arthropathies (NIA) and 22 patients with rheumatoid arthritis (RA). Patients with AS showed higher levels of anti-klebsiella IgA antibodies (IgA-Kp) than NIA and RA patients (4.7 +/- 1.6 U vs 3.7 +/- 1.5 U and 3.1 +/- 1.4 U respectively, p = 0.001). In AS patients a significant correlation between IgA-Kp and levels of C-reactive protein was observed. Although no clear correlation was found between IgA anti-klebsiella and total serum IgA levels, a significant correlation between IgA anti-klebsiella and serum levels of secretory IgA was detected (r: 0.43, p = 0.003). In conclusion, some patients with AS disclosed raised levels of Klebsiella antibodies in sera and this is related to an increase of secretory IgA level. Analysis about the relationship between response to klebsiella and the presence of gut inflammation in AS patients could be of interest.

Sequence similarity between HLA-DR1 and DR4 subtypes associated with rheumatoid arthritis and proteus/serratia membrane haemolysins

Rheumatoid arthritis (RA) is found more often in subjects carrying the HLA-DR1 antigen and some subtypes of the HLA-DR4 antigen than in those without these antigens. Analysis of probes specific for HLA-DR4 has shown that amino acids encoding positions 69-74 (EQRRAA) of the beta chain indicates susceptibility to RA. A hexamer sequence of proteus haemolysin spanning residues 32-37 (ESRRAL) has been identified which resembles biochemically, and discriminates by charge, between HLA types associated with RA (DR1, Dw4, Dw14, Dw15), and those not linked with the disease (Dw10, Dw13).

Ankylosing spondylitis and HLA-B27: restriction fragment length polymorphism and sequencing of an HLA-B27 allele from a patient with ankylosing spondylitis

Two groups of patients with ankylosing spondylitis (AS) from England and Poland were examined for restriction fragment length polymorphisms (RFLPs) associated with the disease. No preferential association was found between the 9.2 kb PvuII fragment in HLA-B27 positive patients with AS compared with HLA-B27 healthy subjects as had been previously reported. In the English group, however, a 14 kb PvuII fragment was more common in HLA-B27 positive subjects with AS than in normal controls. Also 4.6 and 3.7 kb PvuII fragments were more prevalent in subjects without AS than in the group with AS, but these results were confined to the English group. Furthermore, the sequence of an HLA-B*2705 gene isolated from a patient with AS was examined, and no significant differences were found compared with the sequence isolated from a healthy subject. There do not seem to be significant genetic differences in the coding or in the regulatory region in HLA-B27 alleles, in subjects with or without AS.

IgA antibody response to klebsiella in ankylosing spondylitis measured by immunoblotting

IgA antibodies to Klebsiella pneumoniae var oxytoca and Proteus mirabilis were measured in 66 patients with ankylosing spondylitis (AS) and 31 with rheumatoid arthritis (RA) and in 51 healthy control subjects, using an immunoblotting technique. The number of antigenic bands to klebsiella on nitrocellulose membrane was higher in 28 patients with active AS than in 38 patients with inactive AS, 31 patients with RA, and 51 healthy control subjects; comparatively smaller increases were found against proteus. In two patients with AS the synovial fluid and the corresponding serum sample showed an identical antibody pattern. Increases in IgA antibodies to klebsiella in patients with AS confirm previous studies using other techniques.

Ankylosing spondylitis is caused by Klebsiella. Evidence from immunogenetic, microbiologic, and serologic studies

Ankylosing spondylitis is a form of reactive arthritis following Klebsiella infection, usually occurring in an HLA-B27-positive individual. This conclusion is based on evidence obtained from several disciplines: immunogenetic studies show that there is molecular mimicry between HLA-B27 and Klebsiella; increased isolation of fecal Klebsiella has been reported in both Europe and North America; and finally, antibodies to Klebsiella have been demonstrated in ankylosing spondylitis patients in England and Finland. It is suggested that therapeutic trials should be set up with the aim of eliminating Klebsiella microbes, in an endeavor to test the validity of this theory.

HLA and disease

Many human diseases are associated with HLA class I, class II and class III antigens. It appears that the class III antigen disease associations can be explained by a direct defect operating at the level of either the class III gene or its gene product. The mechanism underlying class I and class II antigen disease associations is at present unknown. In this review we have considered thirty diseases which have been ranked according to their relative risk as defined by the frequency of a given HLA antigen in patient and control populations. The chronic inflammatory disorder, ankylosing spondylitis and its association with HLA B27 has been used as a model to study the HLA linked diseases. We have suggested that the disease may be caused by the Gram-negative microorganism Klebsiella which has antigenic similarity to HLA B27. It is proposed that some antibodies made against Klebsiella bind to HLA B27, thereby acting as autoantibodies leading to the pathological sequelae of chronic inflammatory arthritis. This is the crosstolerance hypothesis or molecular mimicry model and it has been compared to the receptor model. It is further suggested that the crosstolerance hypothesis can be utilised as a general theory to explain the association of other diseases with the class I and class II antigens, and offer a possible explanation for the polymorphism of HLA.

The use of enzyme immunoassay (EIA) and radiobinding assay to investigate the cross-reactivity of Klebsiella antigens and HLA B27 in ankylosing spondylitis patients and healthy controls

The binding of rabbit anti-Klebsiella antibodies to tissue-typed lymphocytes obtained from 30 ankylosing spondylitis (AS) patients and 54 healthy subjects has been measured by an enzyme immunoassay method. HLA B27 positive lymphocytes obtained from either AS patients (t = 3.60; p less than 0.001) or healthy subjects (t = 3.77; p less than 0.001) were found to bind Klebsiella antibodies to a significantly greater extent than non-B27 lymphocytes obtained from healthy controls. Absorption studies demonstrated that HLA B27 positive lymphocytes absorbed out significantly more anti-Klebsiella antibodies than HLA B27-negative lymphocytes (t = 6.76; p less than 0.005). These results are compatible with cross-reactivity or molecular mimicry between HLA B27 and epitopes on some Gram-negative bacteria such as Klebsiella.