Circulating antibodies against human colonic extract enriched with a 40 kDa protein in patients with ulcerative colitis

Role of B-Cell Activating Factor (BAFF) in Inflammatory Bowel Disease

As early commencement of inflammatory bowel disease (IBD) treatment has been shown to substantially improve outcomes, it is of utmost importance to make a timely diagnosis of this disease. Despite undisputed sensitivity of fecal calprotectin, the most widely accepted IBD biomarker, in discriminating between irritable bowel syndrome (IBS) and IBD, as well as recognized role in monitoring disease activity and response to therapy, perhaps the biggest setback of calprotectin use in IBD is lack of specificity. Therefore, an additional biomarker in IBD is warranted. B-cell activating factor (BAFF), a member of the tumor necrosis factor (TNF) superfamily, recently emerged as a viable candidate for this role. So far, overproduction of BAFF has been observed in various autoimmune diseases, most notably in systemic lupus erythematosus, where BAFF-inhibitor belimumab was approved for treatment. As BAFF levels were also shown to correlate with indices of IBD, in this review we aimed to summarize the current evidence with respect to the role of BAFF in diagnosis and assessing the activity of IBD, as well as putative therapeutic implications that may arise from exploring of this relation.

Inflammatory bowel disease: exploring gut pathophysiology for novel therapeutic targets

Ulcerative colitis and Crohn's disease are the 2 major phenotypes of inflammatory bowel disease (IBD), which are influenced by a complex interplay of immunological and genetic elements, though the precise etiology still remains unknown. With IBD developing into a globally prevailing disease, there is a need to explore new targets and a thorough understanding of the pathophysiological differences between the healthy and diseased gut could unearth new therapeutic opportunities. In this review, we provide an overview of the major aspects of IBD pathogenesis and thereafter present a comprehensive analysis of the gut pathophysiology leading to a discussion on some of the most promising targets and biologic therapies currently being explored. These include various gut proteins (CXCL-10, GATA-3, NKG2D, CD98, microRNAs), immune cells recruited to the gut (mast cells, eosinophils, toll-like receptors 2, 4), dysregulated proinflammatory cytokines (interleukin-6, -13, -18, -21), and commensal microbiota (probiotics and fecal microbiota transplantation). We also evaluate some of the emerging nonconventional therapies being explored in IBD treatment focusing on the latest developments in stem cell research, oral targeting of the gut-associated lymphoid tissue, novel anti-inflammatory signaling pathway targeting, adenosine deaminase inhibition, and the beneficial effects of antioxidant and nutraceutical therapies. In addition, we highlight the growth of biologics and their targets in IBD by providing information on the preclinical and clinical development of over 60 biopharmaceuticals representing the state of the art in ulcerative colitis and Crohn's disease drug development.

B Cell-Activating Factor as a New Potential Marker in Inflammatory Bowel Disease

BACKGROUND

B cell-activating factor (BAFF) has been proposed to be a regulator of B cell and T cell immune responses and be associated with inflammatory processes in autoimmunity and B cell malignancies. No study has reported the role of BAFF in inflammatory bowel disease (IBD).

AIMS

The purpose of this study was to investigate expression and concentrations of BAFF in IBD and determine its value to discriminate patients with IBD.

METHODS

Seventy-eight ulcerative colitis (UC) patients, 37 Crohn's disease (CD) patients, 12 irritable bowel syndrome (IBS) patients and 44 healthy controls were recruited. We examined serum and faecal BAFF levels using enzyme-linked immunosorbent assay. Intestinal BAFF expression was analysed in biopsies obtained from IBD patients. Intestinal mucosa localization of BAFF was conducted by immunofluorescence.

RESULTS

The median (25th-75th percentile) serum BAFF concentration (pg/ml) was 1430 (1105-1624) in CD patients, 1472 (1018-1772) in UC patients and 977 (482-1345) in healthy controls. Serum BAFF was 64 % sensitive and 93 % specific for identifying active IBD from healthy controls. The BAFF expression was significantly increased in biopsy specimens from IBD patients. Fecal BAFF concentration was 369 (326-493) pg/ml in CD patients, 542 (358-1758) pg/ml in UC patients, 294 (287-299) pg/ml in IBS patients and 295 (284-309) pg/ml in healthy controls. Fecal BAFF was 90 % sensitive and 96 % specific for identifying active IBD from healthy controls and IBS patients.

CONCLUSION

The novel association between BAFF and IBD seems to identify that BAFF might regulate the inflammatory process in these diseases and it appears to be a potential marker of IBD.

Genes differentially regulated by NKX2-3 in B cells between ulcerative colitis and Crohn's disease patients and possible involvement of EGR1

Ulcerative colitis (UC) and Crohn's disease (CD) are two related yet different forms of chronic intestinal inflammation. We investigated the genes regulated by NKX2-3 in B cells from a UC patient by cDNA microarray and compared the results to those genes regulated by NKX2-3 in B cells from a CD patient. Genes regulated by NKX2-3 in B cells from UC were mainly involved in cell growth, inflammation, and immune response. Among the genes regulated by NKX2-3 in both UC and CD, expression of 145 genes was similarly altered and 34 genes was differentially affected by NKX2-3 knockdown. EGR1 was up-regulated in NKX2-3 knockdown B cells from UC while down-regulated in NKX2-3 knockdown B cells from CD. mRNA expressions of NKX2-3 and EGR1 were increased in diseased intestinal tissues from 19 CD patients. NKX2-3 may play different roles in UC and CD pathogenesis by differential regulation of EGR1.

Genes regulated by Nkx2-3 in siRNA-mediated knockdown B cells: implication of endothelin-1 in inflammatory bowel disease

Nkx2-3 gene variants are strongly associated with inflammatory bowel disease (IBD) and its expression is up-regulated in Crohn's disease (CD). However, the nature of its role underlying IBD pathogenesis is unknown. We investigated the genes regulated by Nkx2-3 using cDNA microarray. A small interfering RNA (siRNA)-mediated knockdown of Nkx2-3 in a B cell line from a CD patient was generated. Gene expression was profiled on high-density cDNA microarrays representing over 25,000 genes. Ingenuity pathway analysis (IPA) was used to identify gene networks according to biological functions and associated pathways. Expression profiling analysis by cDNA microarray showed that 125 genes were regulated by Nkx2-3 knockdown (fold change >or=3.0, p<0.01), among which 51 genes were immune and inflammatory response genes. Microarray results were validated by RT-PCR and further confirmed in a B cell line expressing siRNA of Nkx2-3 from an additional CD patient. The results showed that Nkx2-3 was up-regulated (p<0.05) and EDN1 was down-regulated (p<0.05) in B cell lines from CD patients. mRNA expression levels of Nkx2-3 were negatively correlated with those of EDN1 (r=-0.6044, p<0.05). EDN1 was also down-regulated in intestinal tissues from UC patients (p<0.05). Our present results demonstrate that a decrease in Nkx2-3 gene expression level can profoundly alter the expression of genes and cellular functions relevant to the pathogenesis and progression of IBD, such as EDN1.

Hyperactivated B cells in human inflammatory bowel disease

IBD is characterized by a chronic, dysregulated immune response to intestinal bacteria. Past work has focused on the role of T cells and myeloid cells in mediating chronic gastrointestinal and systemic inflammation. Here, we show that circulating and tissue B cells from CD patients demonstrate elevated basal levels of activation. CD patient B cells express surface TLR2, spontaneously secrete high levels of IL-8, and contain increased ex vivo levels of phosphorylated signaling proteins. CD clinical activity correlates directly with B cell expression of IL-8 and TLR2, suggesting a positive relationship between these B cell inflammatory mediators and disease pathogenesis. In contrast, B cells from UC patients express TLR2 but generally do not demonstrate spontaneous IL-8 secretion; however, significant IL-8 production is inducible via TLR2 stimulation. Furthermore, UC clinical activity correlates inversely with levels of circulating TLR2+ B cells, which is opposite to the association observed in CD. In conclusion, TLR2+ B cells are associated with clinical measures of disease activity and differentially associated with CD- and UC-specific patterns of inflammatory mediators, suggesting a formerly unappreciated role of B cells in the pathogenesis of IBD.

Isolation of peptides useful for differential diagnosis of Crohn's disease and ulcerative colitis

BACKGROUND

Phage displayed random peptide technology has been utilised to identify binding epitopes of antibodies or receptor ligands.

AIM

To isolates peptides from a phage library which are specifically recognised by antibodies in serum from patients with Crohn's disease (CD).

METHODS

A phage displayed random peptide library composed of nine amino acids was established and sequentially screened using serum immunogloblin G obtained from CD patients.

RESULTS

Five different CD specific peptides were isolated from the phage library. No homology in amino acid sequences was observed among four (CDP-1, -3 to -5) of the five peptides exhibiting different binding characteristics with each CD patient's serum. In contrast, two peptides (CDP-1 and -2) had similar amino acid sequences and similar binding characteristics. Four multiple antigenic peptides (MAP, CDP-1, -3 to -5) were synthesised, and an enzyme linked immunosorbent assay (ELISA) using the four peptides was developed to detect serum antibodies against them. Fifty two of 92 CD patients (56.5%) were detected by ELISA, none of 20 ulcerative colitis (UC) patients, only one of 25 duodenal ulcer patients, and only three of 48 healthy subjects.

CONCLUSIONS

ELISA using the four peptides isolated in this study may be useful for the differential diagnosis of CD and UC.

Detection of anti-colon antibodies in inflammatory bowel disease using human cultured colonic cells

BACKGROUND

Investigation of anti-colon antibodies may be simplified if a sensitive method and homogeneous source of antigen were available.

AIMS

To examine the anti-colon antibody response using human colonic carcinoma cell lines as antigen.

SUBJECTS

Patients with inflammatory bowel disease and other gastrointestinal disorders and healthy controls were studied.

METHODS

Comparative enzyme linked immunosorbent assays (ELISAs) were performed to assess the value of whole Caco-2, HT-29, and LS-180 cells as antigen. The antigenic determinants of the immune response were characterised by western blot analysis.

RESULTS

Sera demonstrated immunoreactivity against each of the cell lines, but different epitopes were recognised. Applying whole Caco-2 cells as antigen in an ELISA, the prevalence of anti-colon antibodies was significantly greater in patients with ulcerative colitis (36%) than Crohn's disease (13%), other gastrointestinal disorders (13%) and healthy controls (0) (p<0. 05). The immune response was not associated with one predominant antigen.

CONCLUSIONS

Fixed whole cell ELISA is a simple and feasible method for studying the anti-colon antibody response. This response is non-specific, being directed against multiple antigens, and is likely to be an epiphenomenon of inflammatory bowel disease, more so for ulcerative colitis than Crohn's disease.

Autoimmune (Hashimoto's) thyroiditis associated with Crohn's disease

We report the occurrence of autoimmune (Hashimoto's) thyroiditis in three patients with Crohn's disease. Previously, thyroid disease has been described only in association with ulcerative colitis. We review the pertinent literature on thyroid disease in inflammatory bowel disease (IBD) and suggest that this association supports the hypothesis that autoimmunity is involved in the pathogenesis of IBD. Early diagnosis and treatment of thyroid dysfunction in patients with IBD is desirable because thyroid dysfunction worsens the symptoms and course of IBD.

Production of immunoglobulin G and G1 antibodies to cytoskeletal protein by lamina propria cells in ulcerative colitis

BACKGROUND & AIMS

Recent studies suggest an autoantigenic role for tropomyosin-related protein(s) in ulcerative colitis (UC). This study examined whether immunoglobulin G and G1 subclass antibodies against tropomyosins are produced spontaneously by the lamina propria mononuclear cells (LPMCs) that infiltrate the inflamed UC tissue.

METHODS

LPMCs were isolated from colonic biopsy specimens from 29 patients with UC, 15 with colonic Crohn's disease (CD), and 13 with non-inflammatory bowel disease (IBD). The autologous peripheral blood mononuclear cells (PBMCs) were obtained. Cells were cultured in vitro and unstimulated for 10 days. Spontaneous production of immunoglobulin G and G1 antibodies against tropomyosins was measured by enzyme-linked immunosorbent assays using highly enriched tropomyosins from skeletal muscle and colonic mucosa.

RESULTS

The total immunoglobulin G produced by LPMCs from both patients with UC and CD was comparable but higher than from patients with non-IBD (P < 0.05). However, immunoglobulin G antibodies to tropomyosins were higher in patients with UC than in patients with CD (P < 0.04) and non-IBD (P < 0.02). LPMCs from patients with symptomatic UC produced higher immunoglobulin G antibodies to tropomyosins than patients with UC in remission (P < 0.03), symptomatic CD (P < 0.04), and non-IBD (P < 0.02). Immunoglobulin G antibodies to tropomyosins predominantly belonged to immunoglobulin G1 subclass. The autologous PBMCs showed comparable results.

CONCLUSIONS

Immunoglobulin G antibodies predominantly belonging to immunoglobulin G1 subclass and reactive against tropomyosin-related protein(s) are spontaneously produced by LPMCs from the colonic mucosa in patients with UC.

Expression of a unique protein on colon cancer cells that reacts with a novel monoclonal antibody and ulcerative colitis serum

We earlier developed a MoAb, 7E12H12 (IgM isotype), against a protein present in normal colonic epithelial cells. To examine if 7E12H12-reactive protein is expressed in colon cancer cells and is recognized by ulcerative colitis (UC)-associated autoantibody, we investigated several colon cancer cell lines. 7E12H12 reactivity against the cells was examined by indirect immunofluorescence assay and whole cell ELISA against six colon cancer cell lines HT-29, LoVo, COLO 205, DLD-1, LS 180 and SW 1116. A competitive ELISA was developed using 7E12H12 MoAb and patients' serum to examine the cross-reactive antibodies in the serum. Among the six colon cancer cell lines only LS 180, DLD-1 and SW 1116 reacted with 7E12H12 MoAb, while others did not. The mean (+/- s.e.m.) inhibition of the binding of 7E12H12 MoAb to LS 180 cells by UC serum (n = 51) was 42 +/- 2.1%, whereas in normal subjects (n = 17) it was 14 +/- 2.6%, in Crohn's disease (n = 19) it was 15.3 +/- 2.5%, in infectious diarrhoea (n = 10) it was 11% +/- 3%, and in systemic lupus erythematosus (n = 10) it was 2% +/- 0.6%. The inhibition by the UC group was significantly (P < 0.001 - < 0.0001) higher than any of the non-UC groups, and this inhibition was mainly by IgG1 antibody. The protein in the specific colon cancer cells recognized by the 7E12H12 MoAb cross-reacts with UC-IgG1 antibody and may provide an in vitro system to examine the autoimmune mechanisms in UC.

Immunoglobulin G subclass distribution of human anticolon antibodies in ulcerative colitis

Immunoglobulin G (IgG) subclasses of anticolon antibodies were studied in patients with ulcerative colitis (UC) using enzyme-linked immunosorbent assay (ELISA). The concentrations of total serum IgG subclasses were also measured by ELISA. The values for total serum IgG subclasses in patients with UC were not significantly different from those in normal controls, while the ratio of IgG1 to IgG2 in the patients was significantly higher than that in normal controls. All four IgG subclasses of autoantibodies were demonstrated in the sera of the patients. IgG4 anticolon antibodies were detected most frequently (15 out of 18 patients, 83%). IgG2 was the next most prevalent (9 of 18 patients, 50%). The activity of anticolon antibodies in each subclass did not correlate with the concentration of the corresponding serum IgG subclass. Seven cell lines producing anticolon antibodies were obtained from the colonic mucosa of the patients by Epstein-Barr virus (EBV) transformation. IgG subclasses of anticolon antibodies secreted by these cell lines were also varied. IgG4 subclass was secreted by three EBV transformed cell lines, all of which produced IgG4 anticolon antibodies. These results suggest that all four different IgG subclasses could respond to the colon antigens and that various antigens in colonic mucosa or lumen may contribute to the induction of those autoantibodies. In addition, the prominence of IgG4 anticolon antibodies may support the pathogenic role of this subclass in UC as in other autoimmune diseases.

Autoimmunity in ulcerative colitis: tropomyosin is not the major antigenic determinant of the Das monoclonal antibody, 7E12H12

Ulcerative colitis (UC) has a proposed autoimmune pathogenesis. A 40-kD antigen (P40) has been isolated from UC colon, bound to immunoglobulin. Tropomyosin has been reported as the target antigen of a MoAb (7E12H12) raised against P40. We set out to investigate whether tropomyosin is the major antigenic determinant for 7E12H12. Formalin-fixed, paraffin-processed and cryostat sections of fresh frozen colon from patients with UC, Crohn's disease and normals, were immunostained with 7E12H12 and commercial anti-tropomyosin antibodies. In addition, the immunoreactivity of 7E12H12 with cytoskeletal components was examined on human endothelial cells (HUVEC) using anti-tropomyosin as a positive control. Con-focal microscopy was used to determine the subcellular localization of signal. An extract of total colonic protein from UC colon was prepared. Using a combination of Western and immunoblotting (dot-blots), the immunoreactivities of both tropomyosin (porcine and chicken) and colon protein extract with either 7E12H12 or commercial anti-tropomyosin were examined. Immunocytochemically, 7E12H12 localized to the apical and basolateral regions of plasma membrane, and to the supranuclear cytoplasm in colonic epithelium. Using anti-tropomyosin antibody it was not possible to identify the cytoskeleton in colonic epithelium. Cytoskeletal components were identifiable in HUVEC cultures with anti-tropomyosin antibody but not with 7E12H12. P40 antigen was identified in the colon protein extract by immunoblotting with 7E12H12. There was clear immunoreactivity between anti-tropomyosin antibody and both chicken and porcine tropomyosin, and the colon protein extract. 7E12H12 did not bind to either chicken or porcine tropomyosin in appropriately controlled systems. We conclude that the pattern of immunostaining with 7E12H12 is not cytoskeletal, and there is no reactivity in immunoblots, between tropomyosin and 7E12H12. Tropomyosin is not the major target antigen of this antibody in ulcerative colitis.

Circulating immunoglobulin G1 antibody in patients with ulcerative colitis against the colonic epithelial protein detected by a novel monoclonal antibody

Autoimmunity has been implicated in the pathogenesis of ulcerative colitis (UC). Several studies have shown amplified immunoglobulin G1 (IgG1) antibody response in UC; however the immunoreactive antigen(s) is unknown. To study this antigen(s), mucosal colonic extract was prepared by sonication, ultracentrifugation followed by ion exchange chromatography in fast protein liquid chromatography. The fraction (enriched colonic peptide), that was most reactive to a novel monoclonal antibody, 7E12H12 (IgM isotype), was isolated and used to examine the immunoreactivity against the patients' serum samples. Two hundred and thirteen coded samples from 111 patients with UC (symptomatic and untreated (63), symptomatic and treated (26), remission (22)); 47 with Crohn's disease (CD) (40 were symptomatic and untreated, and 30 had colonic disease); 29 with acute diarrhoea caused by specific pathogen(s); 10 with systemic lupus erythematosus, and 16 normal subjects were examined against the enriched colonic peptide by IgG subtype specific enzyme linked immunosorbent assays (ELISAs). Total IgG antibody reactivity was significantly (p < 0.01) higher only in symptomatic and untreated UC patients compared with each of the non-UC group, but the sensitivity was only 50%. IgG2 and IgG3 reactivities were not different among various groups. The IgG1 antibody reactivity against the enriched colonic peptide, however, differentiated UC patients from CD and each of the other non-UC groups. Seventy nine per cent of the patients with UC, treated or untreated, symptomatic or in remission, had significantly (p < 0.0001) higher IgG1 antibody against the enriched colonic peptide when compared with each of the other non-UC groups. Only 12% of CD serum samples and none of the other control serum samples reacted. Using purified serum IgG1 and 7E12H12-IgM, by 7E12H12 reactive peptide indeed reacts with UC-IgG1 antibody but not with control IgG1.

Immunopathogenesis of chronic inflammatory bowel disease

The aetiology and pathogenesis of chronic inflammatory bowel disease are unknown. However, there is circumstantial evidence that immune mechanisms may play a significant role in mediating the gut lesion and various systemic manifestations. The role of the cellular immune system, soluble mediators, including proinflammatory and immunoregulatory cytokines, humoral immunity and mucosal complement activation will be discussed.

Aetiology and pathogenesis of chronic inflammatory bowel disease

While Crohn's disease and ulcerative colitis are both conditions characterized by intestinal inflammation, with some overlap in their clinical and histological features, they are essentially different in pathogenesis. Crohn's disease appears to be primarily a condition of chronic T-lymphocyte activation, with tissue damage induced by secondary macrophage activation. What activates the T-cells is unknown. In this chapter we look at the evidence for and against cell-wall deficient mycobacteria species, viral infection of vascular endothelium and luminal contents as potential mechanisms of chronic activation. In ulcerative colitis, by contrast, there is no strong evidence for T-cell activation, and humoral mechanisms predominate. While the finding of atypical anti-neutrophil cytoplasmic antibodies (P-ANCAs) may be useful in screening, the only novel pathogenetic discovery is the co-localization of a 40 kD colonic autoantibody with immunoglobulins and complement on the apical enterocyte surface. Despite the fundamental differences in initiating mechanisms, the two conditions have many 'downstream' inflammatory processes in common. We discuss the evidence for local production of cytokines, arachidonic acid metabolites and reactive oxygen and nitrogen radicals, highlighting the potential adverse consequences for intestinal vascular integrity.

Enzyme linked immunosorbent assay (ELISA) and immunoprecipitation studies on anti-goblet cell antibody using a mucin producing cell line in patients with inflammatory bowel disease

Circulating anti-goblet cell antibody and its corresponding antigen in patients with inflammatory bowel disease were investigated. Anti-goblet cell antibody in the serum was examined by immunocytochemistry and enzyme linked immunosorbent assay (ELISA), using a colonic cancer cell line, HT29-18-N2, which differentiates into intestinal goblet cells. The frequencies of anti-goblet cell antibody detected by immunocytochemistry were 14 in 48 patients with ulcerative colitis (29%) and five in 15 patients with Crohn's disease (33%). By ELISA, the frequencies of anti-goblet cell antibody were 38% in ulcerative colitis and 33% in Crohn's disease. This antibody did not relate directly to anti-neutrophil cytoplasmic antibodies (ANCA), although the serum samples positive for anti-goblet cell antibody were commonly positive for ANCA in ulcerative colitis. Immunoprecipitation and SDS polyacrylamide gel electrophoresis (PAGE) study showed that the antibody in the ELISA positive serum samples recognised a > 200 kD goblet cell antigen, which remained unchanged after reduction, indicating that it consists of single chain polypeptides. These results suggest that there is a subgroup of inflammatory bowel disease that has circulating anti-goblet cell antibody reactive with a > 200 kD antigen. The antibody detected by newly established ELISA will be a disease marker for this group and the identification of the corresponding antigens may be important for the understanding of the underlying immune abnormalities.

Epithelial deposits of immunoglobulin G1 and activated complement colocalise with the M(r) 40 kD putative autoantigen in ulcerative colitis

The intestinal expression pattern and general tissue distribution of the M(r) 40 kD putative epithelial autoantigen in ulcerative colitis were re-examined by in situ two and three colour immunofluorescence staining including the murine monoclonal antibody 7E12H12. The intestinal distribution was also compared with the epithelial codeposition of IgG1 and activated complement (C3b and terminal complement complex) seen selectively in ulcerative colitis. The M(r) 40 kD antigen was found for the first time in goblet cells of normal terminal ileum and proximal colon but not in rectal goblet cells. By contrast, colonic enterocytes expressed this antigen apically with increasing intensity in a distal direction, expanding to intense cytoplasmic expression in rectal enterocytes. The antigen was also expressed by the epithelium of the fallopian tubes, major bile ducts, gall bladder, and epidermis but not by proximal gastrointestinal tract epithelium or 13 other extra-gastrointestinal organs. Activated complement and IgG1 often colocalised with the M, 40 kD antigen apically on the surface epithelium in active ulcerative colitis but not in Crohn's disease. Our results support the idea that an autoimmune response to this antigen, leading to complement activation mediated by IgG1, is a possible pathogenetic mechanism for epithelial damage and persistent inflammation in ulcerative colitis.

Antineutrophil cytoplasmic antibodies (ANCA) directed against cathepsin G in ulcerative colitis, Crohn's disease and primary sclerosing cholangitis

Autoantibodies directed against polymorphonuclear neutrophils (PMN) have been observed in serum from patients with ulcerative colitis (UC), Crohn's disease (CD) and primary sclerosing cholangitis (PSC) using indirect immunofluorescence and fixed granulocyte ELISA. Our study demonstrates the presence in the serum of these patients of autoantibodies which bind to an azurophilic granule component distinct from proteinase 3, elastase and myeloperoxidase. These autoantibodies thus belong to the ANCA family, but their antigen specificity differs from the already characterized ANCA antigens. We have found that the same ANCA antigen target, named UC-antigen, was recognized by serum IgG from patients with UC, CD and PSC. It was purified by Matrex Gel Orange A dye affinity chromatography and subsequent immunoabsorption of contaminant proteinase 3 with immobilized anti-proteinase 3 MoAb. The identity between this UC antigen and cathepsin G was demonstrated by their coelution from Matrex Gel Orange A column and the parallel titration of cathepsin G-specific enzymatic activity and UC-ANCA binding, both in partially purified UC antigen and in highly pure cathepsin G. Furthermore, the use of cathepsin G ELISA confirmed that UC, CD and PSC patients' IgG did indeed bind to cathepsin G. Comparison of the results obtained with azurophilic granule- and cathepsin G-ELISA as well as inhibition of ANCA binding by anti-cathepsin G polyclonal antibodies, revealed that in some patients cathepsin G is the main azurophilic granule target of ANCA while others have other ANCA specificities. The fact that UC, CD and PSC are frequently associated with cathepsin G ANCA, while rarely occurring in other types of vasculitis, is intriguing but suggests that these diseases may have a common pathogenetic mechanism.

Expression of the 40 kD protein in DLD-1 colon cancer cells and the effect of cytokines

We recently reported the presence of an organ-specific 40 kD colonic protein which acts as an autoantigen(s) in patients with ulcerative colitis. Using a specific monoclonal antibody directed against 40 kD protein (7E12H12, IgM isotype), in conjunction with immunocytochemistry and flow cytometry, we examined the presence of the 40 kD protein on human colon cancer cells, DLD-1, and also characterized the ability of cytokines, IFN-gamma and tumour necrosis factor, to modulate the expression of this protein on these tumour cells. The presence of the 40 kD protein was localized to the plasma membrane; less was present within the cytoplasm. Following exposure to IFN-gamma (10-1000 U/ml), DLD-1 colon tumour cells showed a dose- and time-dependent increase in 7E12H12 antibody associated immunofluorescence, with the maximum 7E12H12 antibody binding observed with 100 U/ml IFN-gamma at 48 h. In contrast, tumour necrosis factor did not alter the levels of anti-40 kD antibody binding over that of control cells. Since IFN-gamma is also known to induce class II major histocompatibility antigens, we examined the possibility of cross-reactivity of HLA class II antigens and Mr 40 kD epitope. Neither pre-incubation of DLD-1 colon tumour cells with anti-HLA class II antibodies followed by 7E12H12 nor co-incubation of both antibodies altered the amount of 7E12H12 antibody binding. Using a direct ELISA, a highly enriched preparation of Mr 40 kD protein reactive to anti-40 kD antibody did not react with HLA class II antibodies. The present results suggest that 40 kD protein is present on DLD-1 human colon tumour cells and that although the 40 kD protein epitope expression is increased by the lymphocyte-derived cytokine, IFN-gamma, the epitope is separate and distinct from the class II HLA antigens. Further studies on the 40 KD protein may elucidate its autoantigenic role in the pathogenesis of inflammatory bowel disease.

Mr 40,000 human colonic epithelial protein expression in colonic mucosa and presence of circulating anti-Mr 40,000 antibodies in cotton top tamarins with spontaneous colitis

Saguinus oedipus, Callithrix jacchus, and Saguinus fuscicollis are three species of New World monkeys which develop a form of colitis that is similar to human ulcerative colitis. Only S oedipus, however, develop colon cancer. We examined intestinal tissues from these animals for the presence of an antigen cross reacting to the Mr 40,000 human colonic epithelial protein that acts as an autoantigen in ulcerative colitis. Using an anti-Mr 40,000 monoclonal antibody (7E12H12, IgM isotype), by an immunoperoxidase assay we showed that all colon specimens from S oedipus reacted with 7E12H12; however, the colonic tissue from C jacchus and S fuscicollis did not. In immunotransblot analysis eluted IgG antibody bound to human ulcerative colitis colon (CCA-IgG) reacted with Mr 40,000 protein(s) present in the extracts of colon from S oedipus animals and humans. Small intestinal tissue reacted neither with 7E12H12 nor with CCA-IgG. In S oedipus, the Mr 40,000 protein was localised exclusively to colonic epithelial cells. Preincubation of seven S oedipus colon specimens with eight of 10 sera from animals with acute or chronic colitis and 0 of four sera from animals without colitis almost completely inhibited the binding of 7E12H12 to the colonic epithelium. Four of these 10 sera inhibited the binding of 7E12H12 to the autologous colon. These results show the presence of circulating autoantibodies in S oedipus with colitis against an epitope(s) on Mr 40,000 protein shared by human and S oedipus colon.

Inflammatory bowel disease. Part I: Nature and pathogenesis

Once regarded as medical curiosities, ulcerative colitis and Crohn's disease have achieved a remarkable change in status recently and today are among the more compelling of all human illnesses. The cause(s) of inflammatory bowel disease (IBD) are not known. Genetic, environmental, microbial, and immunologic factors are involved, but the precise mechanisms are obscure. The incidence of ulcerative colitis is relatively stable, while Crohn's disease continues to increase in frequency. In 10% to 15% of patients, it is hard to differentiate between ulcerative colitis and Crohn's colitis; however, problems with diagnosis usually resolve with time and repeated examinations. In part I of his two-part monograph on IBD, Dr. Kirsner addresses the nature and pathogenesis of the disease. Increased study of ulcerative colitis and Crohn's disease in recent years has generated new knowledge regarding their etiology. Part I focuses on microbial, immunologic, and genetic mechanisms and the inflammatory processes involved in the disease. In part II, which will be presented in next month's issue of Disease-a-Month, Dr. Kirsner deals with the clinical features, course, and management of IBD, based on the author's 55 years of experience with these problems and supplemented by critical examination of the recent (1988-1990) literature. Particular attention is directed to the symptoms and physical findings of ulcerative colitis and Crohn's disease, the laboratory, radiologic, endoscopic, and pathologic features, and the many systemic complications. The IBDs are mimicked by several enterocolonic infections and other conditions, making differential diagnosis necessary. Inflammatory bowel disease in children and the elderly conforms to conventional clinical patterns modified by the health circumstances of the respective age groups. Because the cause of IBD has not been established, current medical therapy is facilitative and supportive rather than curative. The principles of medical treatment are approximately the same for ulcerative colitis and Crohn's disease. Treatment emphasizes a program rather than a drug and also considers the individuality of the therapeutic response. A clearer understanding of dietary and nutritional needs, including hyperalimentation and electrolyte and fluid balance, aids treatment. Antidiarrheal and antispasmodic preparations and sedatives are prescribed for symptom relief. The bowel inflammation is controlled with sulfasalazine or the newer 5-amino salicylic acid (5-ASA) compounds, antibacterial drugs for complications of Crohn's disease and IBD, adrenocortical steroids, and the immunosuppressive compounds 6-mercaptopurine (6-MP), azathioprine, and cyclosporine, as determined in each patient. The surgical procedures available for treatment of ulcerative colitis include total proctocolectomy and ileostomy or ileoanal anastomosis.(ABSTRACT TRUNCATED AT 400 WORDS)

The presence in experimental animals of a colon specific Mr 40,000 protein(s) with relevance to ulcerative colitis

In patients with ulcerative colitis a colon tissue bound IgG and serum antibodies against an Mr 40,000 colonic protein(s) has been identified. Using an anti-Mr 40,000 protein monoclonal antibody, 7E12H12, by an immunocytochemical method, the protein was localised in human tissue exclusively to colonic epithelial cells. In this study the presence of the Mr 40,000 protein was assessed in experimental animals by the direct and inhibition enzyme linked immunosorbent assays (ELISAs) using the anti-Mr 40,000 protein monoclonal antibody, 7E12H12 (IgM isotype). In addition, a total of 129 specimens including colon, small intestine, gall bladder, biliary tract, and kidney from nine strains of rats and mice, and from human tissue were studied by the immunocytochemical method using 7E12H12. All colon specimens from both humans and animals reacted with 7E12H12 in the immunocytochemical and ELISA assays. None of the non-colonic organs reacted with 7E12H12. While in human colon 7E12H12 recognised the absorptive epithelial cells, in all the animals it recognised mainly the colonic goblet cells. Extracts of animal colon but not of small intestine inhibited the binding of 7E12H12 to the human colon extract. This study shows the presence of an organ specific Mr 40,000 colonic epithelial protein(s) in humans and experimental animals. A differing cellular localisation of the Mr 40,000 protein(s) in human v animal tissue was also shown. Further characterisation of the Mr 40,000 protein(s) may provide important clues regarding the autoimmune mechanisms in ulcerative colitis.