Clinical significance of microsatellite instability in the inflamed mucosa for the prediction of colonic neoplasms in patients with ulcerative colitis

BACKGROUND AND AIM: Although molecular mechanisms underlying ulcerative colitis (UC)-associated neoplasms have been studied for years, understanding of these mechanisms remains incomplete and no good predictable marker for development of colonic neoplasms in patients with UC has been established. The aim of this study was to assess if microsatellite instability (MSI) contributes to the development of colonic neoplasms in patients with UC. METHODS: We have examined MSI in chronic inflamed and neoplastic colonic mucosa of UC patients. We have also obtained serial biopsied colonic tissues retrospectively 2-12 years before the final diagnosis from patients with high level MSI (MSI-H+) UC-associated neoplasms, and analyzed MSI using them at different periods. RESULTS: Eight of 12 UC-associated colon cancers (67%), four of six UC-associated high grade dysplasias (67%), and two of six UC-associated low grade dysplasias (33%) revealed MSI-H+ phenotypes. In contrast, 15 of 59 lesions (25%) in inflamed UC mucosa without colonic neoplasm revealed MSI-H +. Interestingly, all four patients with MSI-H+ phenotypes at the final diagnosis of UC-associated colon cancer or dysplasia had already had MSI-H+ at the stage of chronic colitis, 2-12 years before the final diagnosis. CONCLUSION: These results support the notion that MSI contributes to the carcinogenesis of UC-associated neoplasms, and indicate that this analysis in inflamed colonic mucosa at surveillance colonoscopy is useful for identifying UC patients who have high risk for neoplastic progression.     

Bacterial invasion into the colonic mucosa in ulcerative colitis

Abstract This study investigated interactions between mucosal lesions and bacterial invasion in ulcerative colitis using the acridine-orange staining method. In all 16 cases of ulcerative colitis, the mucosa was found to be invaded by small rods and cocci. In five of 10 controls, bacteria were seen only adhering to the mucosa and no bacteria were detected in the five remaining cases. It is suggested that the presence of bacteria in the colonic mucosa may be a factor responsible for the persistence or aggravation of ulcerative colitis.     

Enzymes degrading bacterial chemotactic F-met peptides in human ileal and colonic mucosa

Bacterial chemotactic F-met peptides have been identified in culture supernatants of intestinal bacteria and in human faecal dialysates. These potent inflammatory agents could play a role in intestinal inflammatory disorders should they cross the epithelial barrier of the gut. We have identified mucosal peptidases which degrade F-met-leu-phe (FMLP) in ileal and colonic mucosal biopsies obtained at colonoscopy. A carboxypeptidase, inhibited by D-L-benzyl succinate (BzS), accounted for more than 60% of total FMLP-ase activity, other uncharacterized peptidases contributing the rest of the activity against the intact peptide. An F-met deformylase, inactive against di- and tri-peptides, cleaves released F-met completing the degradation. Total FMLP-ase, carboxypeptidase and F-met deformylase activities were measured in serial mucosal biopsies from 15 control patients undergoing colonoscopy for occult bleeding with negative findings and from 15 patients with ulcerative colitis (UC) and 10 with Crohn's disease (CD). Highest activities were found in terminal ileum and lowest in the rectum. Total FMLP-ase and carboxypeptidase activities were similar in controls and UC patients but were substantially reduced in CD, especially in the terminal ileum (controls 493 +/- 146 and 116 +/- 73 nmol/100 micrograms protein per h, respectively and CD 231 +/- 96 and 41 +/- 36 nmol/100 micrograms protein per h, respectively (P = 0.0018 and 0.015). F-met deformylase activities were similar in all groups. There was no correlation between enzyme activity and severity of inflammation. FMLP degrading peptidases probably contribute to the mucosal barrier of the gut in regions of high bacterial colonization, limiting intestinal absorption and inflammatory responses to these potent bacterial products in the intestinal lumen.     

Location of nitroblue tetrazolium-reducing activity in human colonic mucosa obtained by biopsy

The location of nitroblue tetrazolium-reducing activity was studied in colonic biopsy specimens from 28 patients with ulcerative colitis and from 23 controls. Nitroblue tetrazolium was reduced by epithelial cells, vascular endothelium, and interstitial mononuclear cells of the colonic mucosa from both groups. Blue formazan, a reduced form of nitroblue tetrazolium, was seen faintly after 30 min of culture; the amount increased up to 2 hr tested. The vascular endothelium of the patients with ulcerative colitis reduced nitrobule tetrazolium significantly more than that of the controls. The reduction of nitroblue tetrazolium was graded from 0 to 3 and was 1.0±0.6 in the controls, 1.6±0.8 in ulcerative colitis patients (P<0.05), 1.9±0.7 (P<0.01) in patients with active ulcerative colitis, and 1.4±0.9 in patients with inactive ulcerative colitis (difference not significant). Aggregates of mononuclear cells that reduced nitroblue tetrazolium were found in 10 of 28 patients with ulcerative colitis but not in the controls.     

IL-5 and TNF-alpha participate in recruitment of eosinophils to intestinal mucosa in ulcerative colitis

There is an increased influx of activated eosinophils to the intestinal mucosa in active ulcerative colitis, and an increased release of eosinophil-derived proteins, such as ECP, has also been observed. These findings indicate that eosinophils may contribute to tissue damage and intestinal inflammation in this disease. The relative importance of different chemotactic factors and the impact of steroid treatment on their effect in active ulcerative colitis are not known. We measured the eosinophil chemotactic activity in perfusion fluids from 11 patients with ulcerative colitis before and after steroid treatment and from 7 control patients. The effect of neutralizing antibodies to IL-5 and -8, RANTES, eotaxin, MCP-3, TNF-, GM-CSF was investigated. The chemotactic activity was higher in perfusion fluids from patients than from controls (P = 0.0043). Anti-IL-5 (P = 0.005) and -TNF- (P = 0.017) inhibited the activity in perfusion fluids obtained before treatment. Steroid treatment prevented the effect of all antibodies but had no significant effect on the chemotactic activity. The chemotactic activity correlated with the levels of eosinophil granule proteins in the perfusion fluids. In conclusion, in ulcerative colitis, eosinophils are attracted to the intestinal tissue by chemotactic factors, of which IL-5 and TNF- may be the most prominent steroid-sensitive ones. The steroid-insensitive chemotactic activities remain unidentified.     

Collagenase-3 (MMP-13) expression by inflamed mucosa in inflammatory bowel disease

Objective. To determine whether the expression of collagenase-3 (MMP-13) in biopsies from patients with inflammatory bowel disease is correlated with histological inflammation parameters. Material and methods. Fifty-nine patients with inflammatory bowel disease were included in the study. The control group comprised 20 patients free of inflammatory disease and ten patients with acute diverticulitis. MMP-13 expression was determined by immunohistochemical staining and the specimens were assigned a histological inflammation score. Results. It was found that 62.8% of patients with ulcerative colitis (UC) and 54.1% of patients with Crohn's disease (CD) showed MMP-13-positive immunostaining in biopsies from affected areas. MMP-13-positive staining was more intense in ulcerated colonic mucosa. A positive and significant correlation was found between MMP-13 expression and the histological inflammation scores in mucosal samples from patients with CD (r=0.74, p<0.0001) or UC (r=0.62, p<0.0001). However, no MMP-13-positive immunostaining was found in either the biopsy specimens of the control group or those biopsies taken from patients with UC or CD in microscopically confirmed non-affected areas of the colonic mucosa. Similarly, colonic mucosa samples of the 10 patients with acute diverticulitis did not show immunostaining for MMP-13. Conclusions. Our findings demonstrating the absence of MMP-13 expression in non-inflamed colonic mucosa or in acute diverticulitis, as well as a positive correlation between elevated MMP-13 expression and histological criteria of inflammation in patients with inflammatory bowel diseases (CD and UC) suggest a role of the protease in the pathogenesis of these latter processes.     

Tissue-type plasminogen activator of colonic mucosa in ulcerative colitis

Microvascular endothelial alterations are thought to be a crucial step for development of hemorrhagic changes in various pathological states. In this study, we determined the activity and amount of tissue-type plasminogen activator (t-PA) in the biopsy specimens from sigmoid colon of patients with ulcerative colitis to evaluate endothelial alterations and vascular changes of permeability. The results of this investigation revealed that mucosal amount of t-PA in the active stage of ulcerative colitis was two- to threefold higher than in healthy controls, while t-PA levels in plasma samples showed no remarkable differences among the groups. Increased t-PA activity appeared to correlate well to the degree of inflammation of colonic mucosa, and t-PA amount was still increased in the inactive stage. The present study indicates that t-PA determination in colonic biopsy specimens may be useful for the evaluation of clinical activity of ulcerative colitis in terms of the mucosal microvascular endothelial changes.This work was supported by the grant from the Japanese Ministry of Education No. 63440033 and by the grant from Keio University, School of Medicine.     

Telomere shortening in the colonic mucosa of patients with ulcerative colitis

Telomere length in human somatic cells gradually decreases with the number of cell divisions and is regarded as a marker of somatic cell turnover. Mucosal cells of the affected colon show rapid turnover in individuals with active ulcerative colitis (UC). Telomere length was determined by Southern blot analysis of terminal restriction fragments (TRFs) from the colonic mucosa of 17 patients with UC in remission, two of whom showed dysplasia, and 17 control subjects without colitis. For each individual, mean TRF length was compared between rectal mucosa and unaffected cecal mucosa. The mean TRF length of the rectal mucosa was significantly less than that of cecal mucosa in UC patients (7.87 ± 0.36 kb versus 8.77 ± 0.21 kb; P = 0.0015, Wilcoxon signed rank test), whereas no significant difference was detected in the control subjects. The extent of telomere shortening was 10.6 ± 3.35% in UC patients, compared with 0.8 ± 0.64% in noncolitis controls (P = 0.0024, Mann-Whitney U-test). Four UC patients, two of whom had dysplasia, showed telomere shortening of more than 20% in the rectal mucosa. These observations suggest that telomere shortening in the colonic mucosa of individuals with UC may represent the history of mucosal inflammation during disease of long duration, and that it may contribute to aneuploidy in UC. (Received May 6, 1997; accepted Sept. 26, 1997)     

Microvascular disturbances in the colonic mucosa in antibiotic-associated haemorrhagic colitis: Involvement of platelet aggregation

An ultrastructural study of the colonic mucosa was performed in four patients with antibiotic-associated haemorrhagic colitis and new findings are reported. Colonoscopy was performed and biopsy specimens were obtained within 24 h of the onset of bloody diarrhoea. Colonoscopy demonstrated diffuse oedematous and haemorrhagic mucosa with erosions and white coat. Light microscopy revealed mucosal haemorrhage and inflammatory cell infiltration. Ultrastructurally, platelet aggregation was frequently present in the lumina of colonic mucosal capillaries, causing engorgement of red blood cells in adjacent microvessels. Mild to severe damage was observed in capillary endothelial cells, including discontinuity of basement membranes, gaps between endothelial cells and the destruction of capillaries. There was no evidence of microvascular spasm. In conclusion, our findings suggest that antibiotics directly or indirectly cause microcirculatory disturbances, which result in tissue damage and haemorrhage, in the colonic mucosa.     

靛玉红对溃疡性结肠炎小鼠肠黏膜细胞因子含量的影响

[目的]探讨中药青黛有效成分靛玉红对溃疡性结肠炎(UC)小鼠肠黏膜细胞因子含量的影响.[方法]采用5％葡聚糖硫酸钠(DSS)建立UC小鼠模型,将小鼠随机分为靛玉红高、低剂量组,美沙拉嗪组,模型1、2组和正常组,每组10只.其中模型组于造模7d时处死,其余各组于第7d开始灌胃给药,连续给药7d时处死.ELISA法检测结肠...     

Experimental Ulcerative Colitis Impairs Antioxidant Defense System in Rat Intestine

Increasing attention has been given recently to the role of free radicals in the pathogenesis of ulcerative colitis, since the inflamed intestine is exposed to oxidative stress generated by infiltrating macrophages and neutrophils within the lamina propia. The overall goal of this study was to evaluate whether experimental ulcerative colitis induces significant changes in the antioxidant defense system in an experimental model induced by the intrarectal administration of 2,4,6-trinitrobenzenesulfonic acid. Twenty rats were treated with 80 mg/kg body weight of trinitrobenzenesulfonic acid and 20 with the same volume of 0.9% NaCl. Rats were killed at one and two weeks after treatment to evaluate colon damage by light and electron transmission microscopy. The degree of tissue injury and inflammation was determined by measuring alkaline phosphatase, -glutamyltranspeptidase, and myeloperoxidase activities and prostaglandin E₂ and leukotriene B₄. Glutathione levels and the activity of the enzymes of the antioxidant defense system were determined. Enzymatic markers of colon injury showed higher activities in rats with ulcerative colitis. Concentrations of prostaglandin E₂ and leukotriene B₄ were higher in the groups treated for one week with trinitrobenzenesulfonic acid and markers decreased after two weeks of treatment. All antioxidant enzyme activities were higher at one and two weeks after treatment; however, a significant decrease in total glutathione content was also observed. In conclusion, ulcerative colitis induced by trinitrobenzenesulfonic acid damages the intestinal mucosa and is accompanied by a shift in the antioxidant enzyme activities, and low levels of glutathione. This deficiency in glutathione could be a target for new therapies to treat ulcerative colitis.     

溃疡性结肠炎患者结肠黏膜中Smad3和Smad7表达的研究

目的 探讨Smad3和Smad7在溃疡性结肠炎(UC)中的表达及其与临床病理因素的关系.方法 应用免疫组化SABC法检测60例UC患者的结肠黏膜及16例正常结肠黏膜(对照组)中Smad3和Smad7的表达.回顾性分析Smad3和Smad7的表达与UC临床分期、病变范围和病理组织学分级的关系.结果 Smad3在活动期和缓解期UC中的表达显著低于对照组(P值均＜0.05);其与病变范围无相关性(r_s=-0.192,P=0.141),但与病理组织学分级呈负相关(r_s=-0.283.P=0.029).Smad7在活动期和缓解期UC中的表达显著增强(P值均＜0.05),且活动期显著高于缓解期(Z=2.097,P=0.036);其与病变范围无关(r_s=0.066,P=0.614),但与病理组织学分级呈正相关(r_s=0.453.P=0.000).相关分析结果提示,Smad3和Smad7在UC中的表达水平间呈负相关(r_s=0.420,P=0.001).结论 转化生长因子-β1/Smad蛋白的异常表达与UC的发病机制密切相关,Smad7有可能成为反映UC疾病活动度的生物学指标.     

Effect of the antioxidant Mesna (2-mercaptoethane sulfonate) on experimental colitis

Reactive oxygen species play a key role in intestinal inflammation, although interventional studies using antioxidants have shown only weak beneficial effects both in humans and animals. Hence, our aim was to examine the possible beneficial effect of the antioxidant 2-mercaptoethane sulfonate (Mesna) on experimental colitis. Colitis was induced in rats by intrarectal instillation of trinitrobenzene sulfonic acid (TNB) followed immediately by intrarectal Mesna or saline, administered for 14 days, twice daily. A beneficial effect of Mesna was observed, resulting in a significant reduction in inflammation followed by almost full recovery. iNOS mRNA expression and myeloperoxidase (MPO) activity were significantly increased in the TNB-Mesna group. These results suggest that the induction of iNOS in the presence of Mesna reduced intestinal inflammation. Mesna probably resolved this inflammation by scavenging reactive oxygen species generated by the augmented infiltration of polymorphonuclear leukocytes.     

Fusobacterium varium localized in the colonic mucosa of patients with ulcerative colitis stimulates species-specific antibody

BACKGROUND: Microbial agents are a possible cause of ulcerative colitis. We have previously reported evidence of bacteria invading the colonic mucosa of patients with ulcerative colitis. We have isolated bacteria from inflamed colonic mucosa, examined the localization of the species in the mucosa, and assayed for serum antibodies to the bacteria. METHODS: Cohorts of 31 per group were enrolled from patients with active ulcerative colitis, Crohn's disease, ischemic colitis, and colon adenomas. A group of 31 healthy controls were also studied. The presence of bacteria in biopsies of patients with ulcerative colitis was analyzed by both isolation and immunohistochemistry. Sera from patients were tested for bacterial antibodies using both Western blots and enzyme-linked immunosorbent assay (ELISA). RESULTS: Only sera from patients with ulcerative colitis gave specific reactions with Fusobacterium varium in Western blot assays. The detection rate of specific bands was higher for patients with ulcerative colitis (61%) than for subjects with either Crohn's disease (13%) or healthy controls (29%) (P < 0.001 and P = 0.021, respectively). The ELISA showed that the mean optical densities with extracts of F. varium as antigen were significantly higher for ulcerative colitis patients than for subjects with either Crohn's disease or healthy controls (P < 0.001). Immunohistochemical detection of F. varium in colonic mucosa was significantly higher in patients with ulcerative colitis (84%) than for subjects with either Crohn's disease (16%) or other controls (3-13%) (P < 0.001). CONCLUSIONS: Fusobacterium varium bacteria were present in a significant number of patients with active ulcerative colitis, and should be tested in therapeutic trials in order to confirm the causal relationship between F. varium and ulcerative colitis.     

Lymphoid cell subsets in colonie mucosa and HLA-DR antigens on colonic epithelia in colitis excluding ulcerative colitis and crohn’s disease

Lymphoid cell subsets, including T cells as well as Ig-containing cells in the colonic mucosa and HLA-DR antigens on colonie epithelia, were examined in non-IBD colitis (colitis excluding ulcerative colitis (UC) and Crohn’s disease) by the indirect immunoperoxidase staining method. Mouse anti-CD5, CD8, CD4, IgG, IgAl, IgA2, IgM, IgD, IgE, HLA-DR, and Nula monoclonal antibodies were used as the first antibody. The results were compared to those of the normal controls and UC. T cell subsets in non-IBD colitis were almost similar to those of the controls and UC. The number of Ig-containing cells of all classes, except for IgA, tended to be increased in non-IBD colitis. In particular, both IgG- and IgE-containing cells were significantly increased compared to those in the controls. Compared to UC, IgG-containing cells were decreased in non-IBD colitis. Namely, in non-IBD colitis, as well as in UC, the change of Ig-containing cells (B cell lineage) was more pronounced than that of T cells. The frequency of the expression of HLA-DR antigens on colonie epithelia in non-IBD colitis was 70%, which was significantly higher than that in controls (0%), but significantly lower than that in UC (100%). Whether the differences in the number of IgG-containing cells, and the frequency of epithelial HLA-DR expression between non-IBD colitis and UC was due to the differences of the degree of local inflammation or due to the differences of the nature of the two diseases was not elucidated in this study. This work was partly supported by a grant from the Research Committee for Intractable Intestinal Disease, Ministry of Health and Welfare, Japan.