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There is increasing evidence that the intestinal microflora plays an important role in the pathogenesis of inflammatory bowel disease. In the present study, we examined the role of the resident intestinal flora in our model of dextran sulfate sodium (DSS)-induced acute and chronic colitis in mice.Acute colitis was induced in BALB/c mice with 5% DSS in their drinking water for 7 days. Chronic colitis was established after four cycles of feeding 5% DSS for 7 days and water for 10 days. For eliminating intestinal bacteria, mice were injected intraperitoneally with metronidazole and ciprofloxacin. We analysed four parameters: (1) body weight, (2) length of the colon, (3) histological score, and (4) myeloperoxidase activity.In acute DSS colitis treatment with antibiotics led to an improvement of the histological parameters (epithelial damage, P0.05; inflammatory infiltrate, P0.05) and colon length (P0.0028). A significant reduction in granulocyte infiltration was indicated by a 52.6% reduced myeloperoxidase activity in colonic biopsies. By contrast, in chronic colitis, treatment of mice with antibiotics failed to show significant effects.In acute DSS-induced colitis bacteria and/or bacterial products play a major role in initiation of inflammation but not in chronic DSS colitis.

Background and aims Macrophages play an important role during mucosal inflammation in inflammatory bowel disease (IBD). As the co-stimulatory molecules B7-1 (CD80) and B7-2 (CD86) play an integral role in the activation of T cells by antigen-presenting cells (APC) we investigated the surface expression of B7-1 and B7-2 on colonic macrophages from normal and IBD mucosa. Methods Intestinal macrophages were isolated from biopsies of 13 control persons and 14 patients with IBD (seven with Crohn's disease (CD); and seven with ulcerative colitis (UC)). Cells were characterized by triple fluorescence flow cytometrical analysis using CD33 as macrophage marker. Results The expression of B7-1 (CD80) (9.2% +/- 4.2%) and B7-2 (CD86) (15.1% +/- 7.3%) was low on colonic macrophages from normal mucosa, indicating only a low antigen presenting potential. However, on macrophages from IBD colon there was a significant increase in the expression of co-stimulatory molecules (CD80, 33.8% +/- 8.9%, P = 0.00005 vs. control; CD86, 39.9% +/- 8.8%, P = 0.00002). There was no significant difference between CD and UC in the expression of CD80 (CD, 31.3% +/- 6.7%; UC, 34.4% +/- 13.3%) and CD86 (CD, 41.9% +/- 3.8%; UC, 35.6% +/- 13.8%). While in normal mucosa only 10.6% +/- 4.9% of the macrophages expressed CD14, more than 90% of the CD86/CD80 positive cells of the inflamed mucosa were positive for CD14. Conclusion Colonic macrophages from normal mucosa rarely express the co-stimulatory molecules CD80 and CD86. In IBD a new macrophage population is found with high expression of co-stimulatory molecules presumably responsible for the perpetuated immune response.

Intestinal macrophages play an important role in mucosal inflammation. In normal colonic mucosa we recently demonstrated a unique macrophage phenotype with attenuated immune functions. Here we present an analysis of the alterations of the phenotype of colonic macrophages in inflammatory bowel disease (IBD).Intestinal macrophages were isolated from biopsies of patients with IBD (n =20). Flow cytometric triple fluorescence analysis was applied to study CD14, CD16, CD33, HLA-DR, CD44, CD11b, CD11c and CD3/CD19 expression.In IBD there was an increase in expression not only of CD14 compared to control mucosa (36.0% +/- 13.2% vs. 10.5% +/- 3.8%, P0.0001) but also of CD16 (28.6% +/- 10.3% vs. 10.1% +/- 3.9%, P0.0001), HLA-DR (53.1% +/- 15.9% vs. 27.3% +/- 9.2%, P0.0005), CD11b (42.8% +/- 14.2% vs. 17.4% +/- 6.8%, P0.0001) and CD11c (35.1% +/- 15.9% vs. 17.8% +/- 10.4%, P0.005.). Furthermore, a hitherto undescribed new population of macrophages could be detected by flow cytometry only in patients with ulcerative colitis (CD16++, CD11b++, CD14(low), CD33(low), CD11c-) accounting for 5.8% of all cells isolated.In contrast to colonic macrophages from normal mucosa, there is a significantly higher expression of CD14, CD16, HLA-DR, CD11b and CD11c in IBD, indicating additional macrophage populations in the inflamed mucosa. This may reflect either a recruitment of new cells from the circulation or a change in phenotype of resident cells.

Objective : Previous studies have revealed large variations in the interobserver agreement of dysplasia grading in inflammatory bowel disease. Therefore, we investigated the diagnostic value of two novel monoclonal antibodies (MIB 1 against Ki-67 and PC 10 against PCNA) in the detection of dysplasia. Methods : A total of 62 biopsies were investigated and histologically classified as follows : 13 probably positive for dysplasia ; 15 low-grade dysplasia ; five high-grade dysplasia ; and 15 inflammation without dysplasia and 14 normal controls. The percentage of positive Ki-67- or PCNA-stained nuclei (= labelling index) was determined in relation to the distribution throughout the mucosa. Results : In all biopsies PCNA-labelling index exceeded that of Ki-67-labelling index. In the superficial half of the crypt PCNA- and Ki-67-labelling indices in the biopsies with 'indefinite for dysplasia, probably positive' or low-grade dysplasia exceeded that of normal tissue (P

Ascites and plasma concentrations of soluble tumor necrosis factor receptors p55 and p75 were measured in a prospective study in 34 patients (35 occasions of ascites) with hepatic (5 infected and 21 uninfected) and malignancy-related (9) ascites. All patients had high concentrations of both soluble tumor necrosis factor receptors in ascites and plasma; these were about 500 times higher than the corresponding tumor necrosis factor-α concentrations. Ascites levels of soluble tumor necrosis factor receptors p55 and soluble tumor necrosis factor receptors p75 were significantly elevated in patients with malignancy-related (p55: 26.0 ± 8.6 ng/ml; p75: 20.5 ± 17.4 ng/ml; mean S.D.) and infected ascites (p55: 25.1 ± 10.9 ng/ml, p75: 22.6 ± 11.0 ng/ml) compared with patients with uncomplicated hepatic ascites (p55: 10.1 ± 4.4 ng/ml; p75: 6.0 ± 2.6 ng/ml). Patients with infected or malignancy-related ascites also showed higher soluble tumor necrosis factor receptor concentrations in plasma than did patients with plain hepatic ascites. Successful antibiotic treatment of peritonitis reduced soluble tumor necrosis factor receptor p55 and p75 ascites levels in three patients from 24.2 ± 15.2 ng/ml to 10.7 ± 1.9 ng/ml and from 20.2 ± 14.4 ng/ml to 7.5 ± 1.8 ng/ml, respectively. Soluble tumor necrosis factor receptors p55 and p75 at cutoff levels of 16.5 ng/ml and 9.5 ng/ml, respectively, differentiated between infected or malignant and plain hepatic ascites with diagnostic accuracies of 94% and 89%, respectively. They did not differentiate between infected and malignant ascites. The concentrations of soluble tumor necrosis factor receptor p55 were usually higher in ascites than in plasma in all subgroups of patients. Levels of soluble tumor necrosis factor receptor p75 were also higher in ascites than in plasma in patients with malignant and infected ascites, but soluble tumor necrosis factor receptor p75 levels were usually higher in plasma than in ascites in patients with uncomplicated hepatic ascites. The concentrations of both tumor necrosis factor receptors correlated well in ascites (r = 0.83, p < 0.001) and plasma (r = 0.85, p < 0.001) but only weakly with tumor necrosis factor-α levels in ascites (p55: r = 0.32, p = 0.03; p75: r = 0.29, p = 0.047) and not with tumor necrosis factor-α in plasma. The high soluble tumor necrosis factor receptor concentrations found in ascites may influence the local bioavailability of tumor necrosis factor and might have an impact on the treatment of peritoneal carcinomatosis with recombinant tumor necrosis factor. Furthermore, the determination of soluble tumor necrosis factor receptors could be of value for the differential diagnosis of ascites. (HEPATOLOGY 1992;16:749–755.)