HLA-DR antigen expression in macroscopically uninvolved areas of intestinal epithelia in Crohn's disease

Induction of HLA-DR antigen expression on human colonic epithelium by tumor necrosis factor-alpha and interferon-gamma

BACKGROUND

We investigated the effects of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) on HLA-DR expression on human normal colonic epithelium, using an organ culture technique.

METHODS

Biopsy specimens from normal colonic mucosa were cultured for 24 h with various concentrations of TNF-alpha and/or IFN-gamma. Epithelial HLA-DR antigens were identified by an indirect immunoperoxidase staining method.

RESULTS

No expression of epithelial HLA-DR antigens was observed in specimens cultured with medium alone. Concentrations of 10(3) U/ml or higher of TNF-alpha and 10(2) U/ml or higher of IFN-gamma induced expression of HLA-DR antigens in a dose-dependent manner. Expression of HLA-DR was increased in specimens cultured with both TNF-alpha and IFN-gamma compared with those cultured with either cytokine alone.

CONCLUSIONS

Our findings suggest that both TNF-alpha and IFN-gamma play important roles in regulating the expression of HLA-DR on colonic epithelium in patients with inflammatory bowel disease.

Expression of HLA-DR antigens on colonic epithelium around lymph follicles. An anomalous expression in Crohn's disease

The relationship between the lymph follicle and expression of HLA-DR antigens on the colonic epithelium was investigated. Colonic specimens containing lymph follicles were examined immunohistochemically for HLA-DR expression. Thirty-six biopsy specimens (29 from macroscopically uninvolved areas and seven from aphthoid lesions) were obtained from 10 patients with Crohn's disease, and another 43 specimens were obtained from 33 patients with various intestinal diseases (non-Crohn's disease). HLA-DR antigens were expressed on the epithelium around the lymph follicle in both groups. However, the rate of expression (31/36) in Crohn's disease was significantly higher than that (5/43) in non-Crohn's diseases (P < 0.001). In addition, the extent and intensity of expression were broader and stronger in Crohn's disease than in non-Crohn's disease. This study is the first demonstration of anomalous HLA-DR expression on the epithelium around the lymph follicle in Crohn's disease.

Mucosal defense mechanism in health and disease. Role of the mucosal immune system

The mucosal immune system is characterized predominantly by the secretory antibody response and gut-associated lymphoid tissue, cellular part of the mucosal immune system. The secretory antibody system depends on local production and selective epithelial transport of secretory IgA and IgM. Furthermore, secretory antibodies and interactions between the intestinal epithelium and T cells are involved in the mucosal down-regulation of the systemic immune system. Neuropeptides play a crucial role in the regulation of mucosal immune responses. It is possible that impairment of the mucosal immune response contributes to the pathogenesis of various intestinal diseases, such as inflammatory bowel disease. Until recently, however, mucosal immunity received relatively little attention from both basic and clinical scientists. Further research on mucosal immunity seems to have promise in helping to provide new understanding of the immune mechanisms and pathogenesis of several gastrointestinal and systemic diseases.

Expression of MHC class II antigens (HLA-DR, -DP, and -DQ) on human gastric epithelium

Class II antigen expression on gastric epithelium was investigated using an immunoperoxidase method in relation to the degree of inflammatory cell infiltration in the lamina propria. Sixty-six biopsy specimens from 43 patients with chronic gastritis were examined. The frequency of HLA-DR expression in specimens with cell infiltration was 94%, while that in specimens without cell infiltration was 24%. There was significant difference in the frequency of HLA-DR expression between the two groups (P less than 0.01). HLA-DR was most intensely expressed in the glandular neck portion. The frequency and extent of class II antigen expression on gastric epithelium with cell infiltration were in the following order: DR greater than DP greater than DQ. The extent of DR and DP, but not DQ expression generally paralleled the degree of cell infiltration. Intestinal metaplasia was found in 13 specimens. In the area of intestinal metaplasia, epithelial class II staining was absent except for one specimen. These results suggest that the respective genes of three class II antigens are regulated by different mechanisms and that an immunological mechanism plays a role in the pathogenesis of gastritis.

HLA-DR expression on M cells overlying Peyer's patches is a common feature of human small intestine

The expression of major histocompatibility complex (MHC) class II (HLA-DR) antigens on M cells within follicle-associated epithelial cells (FAE) covering Peyer's patches was analyzed immunohistochemically. HLA-DR antigens were strongly expressed on M cells and cells with dendritic morphology, whereas other FAE covering Peyer's patches showed weak, but definite staining. Dendritic cells were also positive for S-100 protein and IL-1. These findings suggest that M cells as well as dendritic cells within FAE form an antigen-presenting cell system and contribute to the first information releaser for the mucosal immune system.

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)

Class II (HLA-DR, -DP, and -DO) antigens on intestinal epithelia in ulcerative colitis, Crohn's disease, colorectal cancer and normal small intestine

Class II antigens in involved colonic epithelia of ulcerative colitis (UC), Crohn's disease (CD), colorectal cancer, and epithelia of normal small intestine were investigated using an immunoperoxidase method. Ten normal colonic mucosa served as normal controls. Ten specimens were studied for each group. Normal colonic epithelia did not express class II antigens. In colonic diseases; (1) with regard to the frequency and extent of class II antigens on epithelia. HLA-DR antigens were the most highly and greatly expressed, followed by HLA-DP and then HLA-DQ antigens. (2) The extent of HLA-DR and -DP, but not HLA-DQ, expression on epithelia of UC and colorectal cancer seemed to be positively correlated with the degree of mononuclear cell infiltration in the lesion. (3) The extent of class II antigen expression on colonic epithelia in CD was not related to the degree of mononuclear cell infiltration in the lesion. (4) The extent of HLA-DR and -DP expression on epithelia of colorectal cancer seemed to be positively correlated with increasing undifferentiation. In the normal small intestine, where HLA-DR antigens were physiologically expressed on epithelia. HLA-DQ antigens were not expressed. The heterogeneity among colonic diseases, and between the physiological and pathological status, may reflect differences in immunoregulation.