Serum antibodies to mycobacterial antigens in active Crohn's disease

Isotype-specific Antibody Responses to Mycobacterium avium paratuberculosis Antigens Are Associated With the Use of Biologic Therapy in Inflammatory Bowel Disease

BACKGROUND

The role of Mycobacterium avium paratuberculosis [MAP] in inflammatory bowel disease [IBD], especially Crohn's disease [CD] is controversial due conflicting results and lack of reproducibility and standardised tests. The current study focuses on the role of MAP in disease progression and genetic susceptibility, as MAP is likely one of many factors involved in the complex pathogenesis of IBD, potentially affecting a subgroup depending on genetic susceptibility.

METHODS

Serum from 812 patients was evaluated with seven immunoglobulin [Ig] isotype-specific serology tests assessing humoral response to three different MAP antigens. For each of these in total 21 tests, the intra-assay and inter-assay coefficients were used to evaluate test accuracy. Reliable assays were subsequently analysed in relation to disease characteristics and need for biologic therapy/surgery. Genome-wide genotyping was available for all participants. Genetic determinants of humoral response to MAP antigens were evaluated using genome-wide association analysis and polygenic risk scores [PRS].

RESULTS

High IgA or IgM response to MAP2609 was associated with increased use of biologic therapy in CD and ulcerative colitis [UC] [odds ratios 2.69; 95% confidence interval 1.44-5.01; and 2.60, 1.46-4.64, respectively]. No associations were seen for risk of surgery [p-values > 0.29]. We could not identify genetic determinants nor polygenic risk scores for MAP response with genome-wide significance.

CONCLUSIONS

Extensive assays for serological response to MAP were evaluated using stringent criteria for reliability. Increased IgA and IgM response to MAP antigens was seen in patients exposed to biologic therapy, but no genetic determinants underlying this humoral response were found.

The zoonotic potential of Mycobacterium avium ssp. paratuberculosis: a systematic review and meta-analyses of the evidence

This systematic review-meta-analysis appraises and summarizes all the available research (128 papers) on the zoonotic potential of Mycobacterium avium ssp. paratuberculosis. The latter has been debated for a century due to pathogenic and clinical similarities between Johne's disease in ruminants and Crohn's disease (108 studies) in humans and recently for involvement in other human diseases; human immunodeficiency virus (HIV) infection (2), sarcoidosis (3), diabetes mellitus type 1 (T1DM) (7) and type 2 (3), multiple sclerosis (5) and Hashimoto's thyroiditis (2). Meta-analytical results indicated a significant positive association, consistently across different laboratory methods for Crohn's disease [odds ratio (OR) range 4·26-8·44], T1DM (OR range 2·91-9·95) and multiple sclerosis (OR range 6·5-7·99). The latter two and the thyroiditis hypothesis require further investigation to confirm the association. Meta-regression of Crohn's disease studies using DNA detection methods indicated that choice of primers and sampling frame (e.g. general population vs. hospital-based sample) explained a significant proportion of heterogeneity. Other epidemiological studies demonstrated a lack of association between high-risk occupations and development of Crohn's disease. Due to knowledge gaps in understanding the role of M. paratuberculosis in the development or progression of human disease, the evidence at present is not strong enough to inform the potential public health impact of M. paratuberculosis exposure.

The zoonotic potential of Mycobacterium avium spp. paratuberculosis: a systematic review

BACKGROUND

The zoonotic potential of Mycobacterium avium ssp. paratuberculosis (MAP) has been debated for almost a century because of similarities between Johne's Disease (JD) in cattle and Crohn's disease (CD) in humans. Our objective was to evaluate scientific literature investigating the potential association between these two diseases (MAP and CD) and the presence of MAP in retail milk or dairy products using a qualitative systematic review.

METHOD

The search strategy included 19 bibliographic databases, 8 conference proceedings, reference lists of 15 articles and contacting 28 topic-related scientists. Two independent reviewers performed relevance screening, quality assessment and data extraction stages of the review.

RESULTS

Seventy-five articles were included. Among 60 case-control studies that investigated the association between MAP and CD, 37 were of acceptable quality. Twenty-three studies reported significant positive associations, 23 reported non-significant associations, and 14 did not detect MAP in any sample. Different laboratory tests, test protocols, types of samples and source populations were used in these studies resulting in large variability among studies. Seven studies investigated the association between CD and JD, two challenge trials reported contradictory results, one cross-sectional study did not support the association, and four descriptive studies suggested that isolated MAP is often closely related to cattle isolates. MAP detection in raw and pasteurized milk was reported in several studies.

CONCLUSIONS

Evidence for the zoonotic potential of MAP is not strong, but should not be ignored. Interdisciplinary collaboration among medical, veterinary and other public health officials may contribute to a better understanding of the potential routes of human exposure to MAP.

The role of epithelial cells in immune regulation in the gut

A variety of mechanisms contribute to the ability of the gut to either react or remain tolerant to antigens present in the intestinal lumen. Intestinal epithelial cells can control the uptake, transmission and presentation of luminal antigens through an astonishingly diverse set of pathways. Antigens can cross the epithelial barrier via non-specific pinocytotic, specific receptor mediated, or intracellular/paracellular bypass pathways. The differential processing and presentation by a variety of restriction elements may result in the activation of functionally distinct target cell populations which have the capacity to regulate the predominant trend of immune unresponsiveness within the gut.

Oral administration of antigens from intestinal flora anaerobic bacteria reduces the severity of experimental acute colitis in BALB/c mice

Homeostasis between indigenous intestinal flora and host response may be broken in inflammatory bowel disease. The present study explores whether repeated oral administration of intestinal flora antigens can protect mice against dextran sodium sulphate (DSS)-induced colitis. Sonicates of Gram-positive, Gram-negative, or anaerobic resident bacteria isolated from mouse intestinal flora were fed to BALB/c mice by gastric gavage, with or without cholera toxin. After four weekly doses of 1 mg of these antigen preparations (or of PBS as control), DSS colitis was induced. One week later colitis was evaluated by clinical scores and histology. Mice fed a pool of the three sonicates had decreased inflammation scores (5 (1-14); median (range)) compared with PBS-fed control animals (15 (7-19); P < 0.05). Decreased inflammation was observed in mice fed anaerobic bacteria antigens (7 (6-11); P < 0.05 versus control), but not in mice fed a pool of Gram-positive and -negative sonicates (16 (12-16)). Inflammation scores of mice fed antigens with cholera toxin were similar to those of PBS-fed control animals. DSS-induced colitis can be suppressed by oral administration of normal intestinal flora antigens containing anaerobes.

Lack of support for a common etiology in Johne's disease of animals and Crohn's disease in humans

The superficial similarity of Johne's disease to Crohn's disease led to the hypothesis that, like the former. Crohn's disease was caused by Mycobacterium paratuberculosis. Detailed pathologic comparisons, however, reveal little similarity between these two entities, including the lack of important extraintestinal manifestations. Attempts to recover M. paratuberculosis by culture have only rarely succeeded and the significance of spheroplasts that appear more frequently on culture is seriously in question. Five immunocytochemistry studies have failed to find mycobacterial antigens in diseased tissues and the five most recent polymerase chain reaction (PCR) attempts to find genomic evidence of M. paratuberculosis were uniformly negative. Numerous serologic studies failed to demonstrate antibody to M. paratuberculosis and attempts to show cell-mediated immunity were also unrewarding. Inoculation of numerous experimental animals with Crohn's disease tissue has failed to induce Johne's disease, and inoculation of various animal species with M. paratuberculosis has equally failed to result in Crohn's disease. Controlled studies of the treatment of Crohn's disease with antimycobacterial agents have generally resulted in no improvement, and most studies that have shown a positive response are either uncontrolled or include broad-spectrum antibiotics that may be acting on pathogens other than mycobacteria. Finally, although Johne's disease is common in farm animals, and infected animals shed M. paratuberculosis in large numbers, no record of zoonotic transmission has been recorded.

Review: Peyer's patches

The function of Peyer's patches as antigenic sampling sites involves the complex interplay of a variety of mechanisms that aim to recognize luminal antigens, induce an immunological response and decrease the incidence of antigen translocation across the mucosal epithelium. This is achieved by M cells, which facilitate the uptake of luminal antigens, a vascular architecture that promotes the retention of absorbed antigens within the patch interstitium (allowing for maximal antigenic activation of lymphocytes) and the presence of lymphoid follicles that contain antigen-presenting cells and lymphocytes. Lymphocytes encountering antigen in the Peyer's patches proliferate, differentiate into fully mature antigen-specific effector cells and migrate to the mesenteric lymph nodes where they undergo final maturation. The mature lymphocytes then enter the systemic circulation and migrate throughout the other mucosa-associated lymphoid tissues of the body and "home' into the gut via high endothelial venules and gut-associated lymphoid tissue-specific adhesion molecules, providing antigen-specific lymphocytes at sites likely to re-encounter the antigen.

Peripheral cell-mediated immune response to mycobacterial antigens in inflammatory bowel disease

A mycobacterial etiology has been proposed in Crohn's disease (CD). We have sought evidence of increased or modified T lymphocyte immune responses to Mycobacterium tuberculosis and Myco, paratuberculosis in patients with CD (n = 13), compared with ulcerative colitis (UC; n = 17) and controls (n = 17). Peripheral blood cells were cultured with phytohaemagglutinin (positive mitogen control), mycobacterial purified protein derivative (PPD) preparations, lysates, column fractions and whole, heat-killed bacteria. Responses of T cells and T cell subsets were assessed by expression of activation markers (CD25, CD69), coupled with blastogenesis assays (3H-thymidine uptake) and estimates of proliferation. Virtually all patients responded to Myco. paratuberculosis and Myco. tuberculosis antigens. There were no significant differences between patient groups, although there was a very high overall correlation (r = 0.95; P < 0.0001) between responses to the two mycobacterial species. Most of the activation and proliferative responses resided in the CD4+ (T helper) subset. Although up to 15% of CD8+ (suppressor/cytotoxic) cells also became activated, the CD8+ cells did not proliferate subsequently. Cells expressing the alternate gamma delta form of the T cell receptor (TCR gamma delta+) did not activate or proliferate in response to mycobacterial antigens. There were no differences in any of these parameters between patient groups. We conclude that there is no specific increase or alteration in cell-mediated anti-mycobacterial immunity in inflammatory bowel disease (IBD). Thus our data do not support a mycobacterial etiopathology of Crohn's disease.

Detection of anti-cord factor antibodies in intestinal tuberculosis for its differential diagnosis from Crohn's disease and ulcerative colitis

We have developed a diagnostic method for pulmonary tuberculosis by detecting antibody to cord factor using enzyme-linked immunosorbent assay (ELISA). This study was to evaluate the usefulness of our method for a diagnosis of intestinal tuberculosis, and especially its ability to differentiate this disease from other inflammatory bowel diseases. Antibodies of the immunoglobulin G class against cord factor (trehalose-6,6'-dimycolate) from 27 patients with intestinal tuberculosis, 16 patients with Crohn's disease (CD), and 27 patients with ulcerative colitis (UC) were tested by ELISA with cord factor purified from Mycobacterium tuberculosis H37Rv as the antigen. Twenty-three of the 27 patients with intestinal tuberculosis (85%) showed elevated values distinct from healthy controls. None of the patients with CD showed an elevation of antibody titers. Of the 27 patients with UC, 26 (96%) did not show any anti-cord factor antibody elevation. We conclude that this method is simple and results are reproducible. The results of our study justify undertaking the detection of anti-cord factor antibodies to diagnose intestinal tuberculosis.

Effect of intestinal resection on serum antibodies to the mycobacterial 45/48 kilodalton doublet antigen in Crohn's disease

Interest in the role of mycobacterial infection in Crohn's disease has been revived by the cultural detection of Mycobacterium paratuberculosis in patients with Crohn's disease. This hypothesis was examined serologically using assays with high specificity for Crohn's disease. The effect of intestinal resection on serum antibodies specific for Crohn's disease was investigated with an immunoblot assay and an enzyme linked immunosorbent assay using the 45/48 kilodalton doublet antigen of Mycobacterium tuberculosis. Antibodies were detected in 64.7% of patients with Crohn's disease (n = 17), 10% of patients with ulcerative colitis (n = 10), 5% of patients with carcinoma of the colon (n = 20), and none of 10 healthy subjects with the immunoblot assay. Statistical comparison of the Crohn's disease patients with each control group resulted in p = 0.0000236. Immunoglobulin G was essentially unchanged 75 days (mean) after surgery. After more than 180 days, however, the antibody response was reduced in all of five patients studied, and was no longer demonstrable in two of them (40%). Simultaneously, the Crohn's disease activity index (CDAI) decreased. Both the high specificity of this assay for Crohn's disease and the diminished antibody response after intestinal resection in parallel with decreased CDAI support a mycobacterial aetiology of Crohn's disease.

Inflammatory bowel disease. The case for an infectious etiology

The infectious hypothesis for IBD is certainly not new. The evidence for an infectious agent is tantalizing but not yet convincing. A failure to demonstrate a specific agent in the inflammatory process could mean that many different organisms are involved, or several organisms that, by themselves, do not cause disease interact. All candidate organisms proposed thus far are compatible with either hypothesis. Nevertheless, interaction between an agent(s) in a host modified by immunologic and genetic factors is still an attractive hypothesis for the cause of these illnesses.

Paratuberculosis

Paratuberculosis (Johne's disease) is a chronic, wasting, widespread mycobacteriosis of ruminants. It involves extensive mycobacterial shedding, which accounts for the high contagiousness, and ends with a fatal enteritis. Decreases in weight, milk production, and fertility produce severe economic loss. The DNA of the etiological agent (Mycobacterium paratuberculosis) has a base composition (66 to 67% G+C) within the range of that of mycobacteria (62 to 70% G+C), a size (4.4 x 10(6) to 4.7 x 10(6) bp) larger than that of most pathogenic mycobacteria (2.0 x 10(6) to 4.2 x 10(6) bp), and a high relatedness (> 90%) to Mycobacterium avium DNA. However, the DNAs of the two organisms can be distinguished by restriction fragment length polymorphism analysis. M. paratuberculosis genes coding for a transposase, a cell wall-associated protein (P34), and two heat shock proteins have been cloned and sequenced. Nucleic acid probes (two of which are species specific) are used, after PCR amplification, for M. paratuberculosis identification in stools and milk. As in leprosy, with disease progression, cellular immune reactions decrease and humoral immune reactions increase. Cutaneous testing with sensitins, lymphocyte proliferation assays, and cytokine tests are used to monitor cellular immune reactions in paratuberculosis, but these tests lack specificity. Complement fixation, immunodiffusion, and enzymometric tests based on antibodies to M. paratuberculosis extracts, to mycobacterial antigen complex A36, to glycolipids, and to proteins help identify affected cattle but are not species specific. The carboxyl-terminal portion of the 34-kDa cell wall-associated A36 protein (P34) carries species-specific B-cell epitopes and is the basis for an enzyme-linked immunosorbent assay. Diagnostic tests for paratuberculosis are also used in Crohn's disease, a chronic human ileitis mimicking Johne's disease, in which isolates identified as M. paratuberculosis have been found.

Occurrence, in Crohn's disease, of antibodies directed against a species-specific recombinant polypeptide of Mycobacterium paratuberculosis

Sera from patients with Crohn's disease and control were analyzed by an enzyme-linked immunosorbent assay based on the Mycobacterium paratuberculosis-specific recombinant polypeptide a362. Anti-a362 immunoglobulin G (IgG) (P < 0.05) and IgA (P < 0.001) titers were higher in patients with Crohn's disease than in controls. A monomodal Gaussian distribution of anti-a362 IgA levels were found for controls, and a bimodal distribution was found for patients with Crohn's disease. An M. paratuberculosis etiology is suggested for the 36% of patients with Crohn's disease who had an anti-a362 IgA level higher than that of controls.

Intestinal expression and cellular immune responses to human heat-shock protein 60 in Crohn's disease

Changes in the intestinal expression of the endogenous human 60-kDa heat-shock protein (HSP60) were investigated in patients with Crohn's disease. HSP60 immunoreactivity was detected in epithelial cells, vascular smooth muscle, and nerve cell bodies of both small and large bowel from patients with Crohn's disease. However, control tissue showed a similar pattern of HSP60 expression. Western blot analysis confirmed that the HSP60 immunoreactivity detected in the intestine corresponded to the 60-kDa HSP. The proliferative response of peripheral blood lymphocytes (PBL) and intestinal intraepithelial lymphocytes (IEL) to recombinant human HSP60 was examined. The results indicate that there was no significant difference in responses between patients with Crohn's disease and controls. Furthermore, there was no increase in the proportion of gamma/delta T cell receptor-bearing T cells in PBL from patients with Crohn's disease cultured for six days in the presence of human HSP60 as compared to control patients. These results suggest that endogenous human HSP60 is unlikely to be a target for an autoimmune response in patients with Crohn's disease.

Helicobacter pylori infection in Japanese patients with adenocarcinoma of the stomach

To examine the association of Helicobacter pylori infection with adenocarcinoma of the stomach in Japanese patients, we studied 29 patients and 58 matched controls. Ascertainment of H. pylori status was based on the presence of specific IgG to H. pylori. For the entire group, an association of this infection with gastric adenocarcinoma was suggested but not statistically significant. For patients in a putatively high-risk subgroup (non-cardia tumors and age < or = 70 years), the association was significant. Assays detecting serum IgA to whole H. pylori cells and cytotoxin, IgG to cytotoxin and Hp54K (the heat-shock protein homolog) and serum neutralization of cytotoxin activity each showed clear differences between H. pylori-infected and uninfected persons in this population. However, for none of these assays was there a significant difference between values for H. pylori-infected persons with or without gastric cancer. Thus, while H. pylori infection was associated with non-cardia gastric cancer in Japanese persons < or = 70 years of age, use of these additional serologic markers did not define additional factors that might be associated with increased risk.

Antibodies to Mycobacterium paratuberculosis and nine species of environmental mycobacteria in Crohn's disease and control subjects

Cultural and serological studies have provided limited, often conflicting, evidence of a role for mycobacteria in the pathogenesis of Crohn's disease. Interest has focussed on Mycobacterium paratuberculosis, previously considered to be common in the environment with no major role as a human pathogen. Whether a specific serum antibody response to mycobacteria occurs in Crohn's disease or ulcerative colitis was investigated. Sera from patients with Crohn's disease (n = 38), ulcerative colitis (n = 15), and a healthy control population (n = 30) were assayed in an enzyme linked immunosorbent assay (ELISA) using eight filtered sonicate mycobacterial preparations and a purified protein derivative made from the bovine tubercle bacillus. In addition, IgG, IgM, and IgA levels to M paratuberculosis were determined in sera from patients with active (n = 24) or inactive (n = 29) Crohn's disease and the control populations. There was strong evidence of contact with environmental mycobacteria in all patients and control populations, with the greatest responses to preparations of M avium, M tuberculosis, and M kansasii. A large proportion of patients with Crohn's disease had antibodies that bound most antigens tested but there were no statistical differences between these values and those of the control population. Similarly, there were no differences in antibody levels to M paratuberculosis in patient and control groups. Although a subset of patients with active Crohn's disease (25%) had IgG concentrations that exceeded the control mean by more than 2 SD, this phenomenon may not be specific to Crohn's disease: 20% of a small group of patients with coeliac disease had similarly raised IgG levels to M paratuberculosis. These findings do not provide serological evidence of a role for this organism in the pathogenesis of Crohn's disease.

Circulating antibodies to heat-shock protein 60 in Crohn's disease and ulcerative colitis

Heat-shock proteins (HSPs) are highly conserved immunogenic intracellular molecules that are induced by inflammatory mediators and may induce autoimmune phenomena in vivo. We have recently demonstrated the increased expression of HSP-60 in the colonocytes of patients with ulcerative colitis. To study further the role of HSP-60 in inflammatory bowel disease, we have now measured antibodies to recombinant mycobacterial HSP-65 (a member of the HSP-60 family) in patients with Crohn's disease, ulcerative colitis, healthy volunteers and, as disease controls, patients with confirmed bacterial diarrhoea. In comparison with healthy controls (n = 20; median level of 89 ELISA units; range 24-292), serum IgA HSP-60 antibodies were elevated in Crohn's disease (n = 21; 157; 57-364; P < 0.05) and active ulcerative colitis (n = 16; 188; 58-373; P < 0.01) but not bacterial diarrhoea (n = 10; 106; 51-285). Increased IgA HSP-60 antibody levels in patients with inflammatory bowel disease may occur as the result of HSP release from injured gut epithelium; alternatively, increased intestinal permeability could facilitate mucosal access of luminal antigens and the generation of cross-reactive anti-bacterial HSP antibodies.

Immunoglobulin A (IgA) and IgG serum antibodies to mycobacterial antigens in Crohn's disease patients and their relatives

Sera from patients with Crohn's disease, their relatives, their spouses, and unrelated healthy controls were assayed by enzyme-linked immunosorbent assay for immunoglobulin G (IgG) and IgA antibodies to Mycobacterium tuberculosis, M. avium, and M. gordonae. The patients had significantly higher IgA responses to mycobacterial antigens than did either their relatives or the controls. On the other hand, both the patients and their relatives had significantly higher IgG responses against these antigens than did the controls. The elevated IgA response was more pronounced against isopentanol-extracted whole bacterial cells than it was against soluble protein extracts, and it appeared to be directed against fixed surface antigens that lie under the loosely bound peptidoglycolipid or glycolipid antigens of mycobacteria.

Mucosal cell-mediated immunity to mycobacterial, enterobacterial and other microbial antigens in inflammatory bowel disease

Culture studies have suggested that Mycobacterium paratuberculosis may play a role in the aetiology of Crohn's disease. However, evidence of sensitization to mycobacterial antigens amongst patients with Crohn's disease has not yet been adequately demonstrated. Previous studies of cell-mediated immunity (CMI) in Crohn's disease were restricted to responses of peripheral blood mononuclear cells (PBMC) to mycobacterial antigens. In this study we have investigated the proliferative responses of both PBMC and mesenteric lymph node mononuclear cells (MLNMC) to a range of mycobacterial and non-mycobacterial antigens. There was no evidence of specific sensitization in the responses of MLNMC and PBMC from patients with inflammatory bowel disease (IBD) to the mycobacterial antigens. However, anergy to M. paratuberculosis could not be excluded. IBD MLNMC responses to most antigens were generally greater than those of PBMC, which were often undetectable. When compared with controls, there was evidence of increased CMI to a range of non-mycobacterial antigens, especially Yersinia enterocolitica, amongst both MLNMC and PBMC from patients with Crohn's disease and ulcerative colitis (UC). These results do not provide support to the proposed role of mycobacteria in the pathogenesis of Crohn's disease, but indicate that further investigation may determine a role for bacterial-specific T cell-mediated responses in the pathogenesis of IBD.

Antibodies to Mycobacterium paratuberculosis in patients with Crohn's disease

IgG antibodies against Mycobacterium paratuberculosis protoplasmic antigen were looked for by an enzyme immunosorbent assay in patients with Crohn's disease, Ulcerative colitis, active pulmonary tuberculosis, past pulmonary tuberculosis, and in healthy controls. Serum reactivity for these antibodies was not correlated to PPD skin test positivity without history of mycobacterial disease. A cutoff based on the mean absorbance value of a pool of healthy blood donors was chosen. Positive values were found in 12/24 (50%) patients with active pulmonary tuberculosis and 2/10 (20%) skin-test-positive subjects with past pulmonary tuberculosis as expected, because antigenic sharing is common among different mycobacteria. The control group of blood donors showed borderline positivities in 3/149 cases (2.01%). Positive values were found in 4/108 (3.70%) patients with Crohn's disease and 2/40 (5%) with ulcerative colitis. We conclude that our data do not support a causal relationship between the M. paratuberculosis and Crohn's disease, but occasional patients with inflammatory bowel diseases show unexpected positivities for these mycobacterial antibodies.

Immunohistochemical characterization, distribution, and ultrastructure of lymphocytes bearing T-cell receptor gamma/delta in inflammatory bowel disease

Phenotypic characterization and distribution of gamma/delta T lymphocytes in the intestinal mucosa were investigated in ulcerative colitis and Crohn's disease by immunohistochemistry. The ratio of delta(+) cells to CD3(+) cells in the intraepithelial space of colon was decreased in Crohn's disease (13%) and strikingly decreased in ulcerative colitis (8%) compared with the control (36%). Delta(+) cells in the lamina propria were also decreased, particularly in the distal ileum of Crohn's disease (4%), compared with the control (15%). On the contrary, the cells gathered at the severe inflammatory sites with other inflammatory cells, including beta(+) cells, and were densely distributed in the T-cell zone around lymphoid follicles. Phenotypic characterization showed that delta(+) lamina proprial lymphocytes of colon were mainly CD4(-)CD8(-) in the control (80%) and Crohn's disease (59%). However, in ulcerative colitis, CD4(-)CD8(-) delta(+) lymphocytes were rarely found (3%). This reflects the difference of immunologic background between the two diseases. Immunoelectron microscopically, these cells in inflammatory bowel disease were rich with vesicular structures in cytoplasms, whereas those in the control group contained electron-opaque granules. The decrease and the morphological change may be closely related to the weakness of mucosal defense.

Investigations on etiology of Crohn's disease. Humoral immune response to stress (heat shock) proteins

Many investigators have tried to prove a relationship between Crohn's disease and Mycobacteria. Recent evidence suggests that some autoimmune diseases may be initiated through "molecular mimicry" between mycobacterial stress protein antigens and their human homologs. We investigated whether antibody to stress proteins was more frequent in patients with Crohn's disease than controls. We used ATP binding to separate stress proteins (heat-shock-induced, de novo-synthesized, and constitutively expressed ATP-binding proteins) from crude extracts obtained from Mycobacteria and from an SV40-transformed human epithelial cell line that expresses a heat-shock protein, hsp73, as a complex with SV40 T antigen. We used immunoblots to compare sera from 34 patients with Crohn's disease, 14 with ulcerative colitis, and 14 with duodenal or gastric ulcers (noninflammatory bowel disease control patients). We found no statistically significant pattern or frequency of antibodies against single proteins or a combination of mycobacterial or human stress proteins. These observations do not support the hypothesis that a humoral immune response to stress proteins of Mycobacteria is important in the pathogenesis of Crohn's disease.

Antibody to selected strains of Saccharomyces cerevisiae (baker's and brewer's yeast) and Candida albicans in Crohn's disease

IgG serum antibody was measured by ELISA in patients with Crohn's disease (15), ulcerative colitis (15), and in normal controls (15) to 12 strains of Saccharomyces cerevisiae (baker's and brewer's yeast) and to the two major serotypes of the commensal yeast Candida albicans. Antibody to 11 of the 12 strains of S cerevisiae was raised in patients with Crohn's disease but not in patients with ulcerative colitis when compared with controls (p less than 0.001). The pattern of antibody response to these 11 strains was variable, however, suggesting the likelihood of antigenic heterogeneity within the species. Antibody to C albicans was not significantly different in patient and control groups. The specificity of this unusual antibody response in Crohn's disease for S cerevisiae suggests that it is not simply the result of a generalised increase in intestinal permeability. Furthermore, because brewing and baking strains detected the response, the relevant antigen(s) are presumably common in the diet. Hypersensitivity to dietary antigens may be involved in the pathogenesis of Crohn's disease, and the role of S cerevisiae requires further investigation.

Immunohistochemical examination for mycobacteria in intestinal tissues from patients with Crohn's disease

We conducted an immunohistochemical search for mycobacteria in the intestinal tissues of patients with Crohn's disease. Tissues obtained by biopsy or surgical resection and fixed by a variety of methods (formalin, periodate-lysine-paraformaldehyde, fresh-frozen) were reacted by an immunoperoxidase method with antibodies to (a) Mycobacterium paratuberculosis strain linda, (b) M. tuberculosis, and (c) the common mycobacterial antigen, lipoarabinomannan. Each of the antibody preparations was shown capable of detecting a variety of typical and atypical mycobacteria (M. tuberculosis, M. kansasii, M. fortuitum, M. chelonei, M. paratuberculosis, and cell wall-defective as well as cell wall-intact forms of M. avium intracellulare) under conditions identical to those used for staining the patients' tissues. We did not detect mycobacteria in any of the 67 specimens from 30 patients examined. These results, in conjunction with those of our previous serologic studies, do not support the hypothesis that infection with a Mycobacterium causes Crohn's disease.

Antimycobacterial chemotherapy in inflammatory bowel disease

We report on a case, ulcerative colitis and another of Crohn's disease. During a relapse which was unresponsive to conventional therapy, acid-fast bacilli were found in colonic biopsies. Conventional therapy was substituted with antimycobacterial chemotherapy (rifampicin, isoniazid and ethambutol) which was responsible for a marked improvement. However, a relapse occurred during chemotherapy and no acid-fast bacilli were found. The patients became responsive to sulphasalazine and corticosteroid therapy once again. It appears that Mycobacteria play a collateral role in inflammatory bowel disease and that once they have been eliminated the original disease re-emerges.

Crohn's disease and mycobacteria: two cases of Crohn's disease with high anti-mycobacterial antibody levels cured by dapsone therapy

Five patients with Crohn's colitis or ileocolitis (CD) refractory to conventional therapy were enrolled in an open trial with dapsone (100 mg/day). This therapy was apparently effective in two out of five patients. In these patients we observed a clinical improvement after one month of therapy and, in the first patient, a complete healing of all the cutaneous and rectal ulcers. In the two responders antibody levels to a soluble extract of M. paratuberculosis (MPSE) were significantly greater than in the three non-responders (P = 0.03); in the first patient, moreover, there was a rise of 39% in antibody titres following the treatment. This rise in antibody levels, that might be expected following death of the pathogen and release of antigen, is similar to that observed after treatment of tuberculosis. Our data suggest that a mycobacterial species or another pathogen that cross-react with those of MPSE, sensitive to dapsone, may in a subset of cases be responsible for the development of CD. This is the first report of clinical cure with an agent active against specific bacterial species, associated with immunologic confirmation of a response.

Crohn's disease and the mycobacterioses: a review and comparison of two disease entities

Crohn's disease is a chronic granulomatous ileocolitis, of unknown etiology, which generally affects the patient during the prime of life. Medical treatment is supportive at best, and patients afflicted with this disorder generally live with chronic pain, in and out of hospitals, throughout their lives. The disease bears the name of the investigator who convincingly distinguished this disease from intestinal tuberculosis in 1932. This distinction was not universally accepted, and the notion of a mycobacterial etiology has never been fully dismissed. Nevertheless, it was 46 years after the distinction of Crohn's disease and intestinal tuberculosis before research attempting to reassociate mycobacteria and Crohn's disease was published. Recently, there has been a surge of interest in the possible association of mycobacteria and Crohn's disease due largely to the isolation of genetically identical pathogenic Mycobacterium paratuberculosis from several patients with Crohn's disease in the United States, the Netherlands, Australia, and France. These pathogenic organisms have been isolated from only a few patients, and direct evidence for their involvement in the disease process is not clear; however, M. paratuberculosis is an obligate intracellular organism and strict pathogen, which strongly suggests some etiologic role. Immunologic evidence of a mycobacterial etiology, as assessed by humoral immune determinations, has been conflicting, but evaluation of the more relevant cellular immunity has not been performed. Data from histochemical searches for mycobacteria in Crohn's disease tissues have been equally conflicting, with acid-fast bacilli detected in 0 to 35% of patients. Animal model studies have demonstrated the pathogenic potential of isolates as well as elucidated the complexity of mycobacterial-intestinal interactions. Treatment of Crohn's disease patients with antimycobacterial agent has not been fully assessed, although case reports suggest efficacy. The similarities in the pathology, epidemiology, and chemotherapy of Crohn's disease and the mycobacterioses are discussed. The issue is fraught with controversy, and the data generated on the association of mycobacteria and Crohn's disease are in their infantile stages so that a general conclusion on the legitimacy of this association cannot be made. While no firm evidence clearly implicates mycobacteria as an etiologic agent of Crohn's disease, the notion is supported by suggestive and circumstantial evidence and a remarkable similarity of Crohn's disease to known mycobacterial diseases.