Atsuhiro Iwai

Reduced sensitivity of inducible nitric oxide synthase-deficient mice to chronic colitis.

Abstract Background: Overproduction of nitric oxide by the inducible form of nitric oxide synthase (iNOS) has been implicated in colitis. Different authors have postulated both toxic and protective effects of nitric oxide (NO) in the pathophysiology of active inflammation. The objective of this study was to examine the role of iNOS in experimental chronic colitis using iNOS-deficient mice. Methods: For induction of colitis, mice received three cycles of 2% of dextran sodium sulfate (DSS) (M.W. 40,000) treatment in drinking water. The degree of colonic inflammation, leukocyte infiltration, and the expression of cell adhesion molecules were determined. INOS expression and nitrotyrosine were also determined by immunohistochemistry. Results: After DSS treatment, a moderate colitis with marked cell infiltration was observed. Intense expression of iNOS was observed on infiltrating cells as well as on the colonic mucosal epithelium in these animals. In the iNOS-deficient mice, tissue damage was significantly diminished. No iNOS or nitrotyrosine staining was found in iNOS-deficient mice. The number of infiltrating cells and the expression of mucosal adressin cell adhesion molecule-1 were significantly attenuated in the DSS-treated colon of iNOS-deficient mice. Conclusion: Induction of iNOS seems to act as a critical toxic effector molecule in the pathogenesis of chronic colonic inflammation.

Expression of bone morphogenetic proteins in colon carcinoma with heterotopic ossification.

Here we report the case of a 50‐year‐old woman with adenocarcinoma of the colon, showing heterotopic ossification. The patient was referred to our hospital for investigation of anemia secondary to occult gastrointestinal blood loss. By colonoscopy, an irregular polypoid mass was found in the ascending colon. A biopsy of the lesion revealed moderately to poorly differentiated adenocarcinoma with heterotopic ossification. A right hemicolectomy was done and revealed areas of heterotopic bone within the tumor, but no ossification was evident in the metastatic lesions within the mesenteric lymph nodes. The formation of heterotopic bone in gastrointestinal tumors is rare and its exact mechanism is unknown. Immunohistochemical localization of bone morphogenetic proteins (BMP), known to be primary inducers of new bone formation, was determined. BMP‐5 and ‐6 were prominent in the cytoplasm of tumor cells, and they stained weakly in osteoblast‐like cells adjacent to newly formed bone. Cytoplasmic staining for BMP‐2 and ‐4 was weak in tumor cells, osteoblast‐like cells, and stromal fibroblast cells. BMP may play an important role in heterotopic ossification in colon adenocarcinoma.

Involvement of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) in the pathogenesis of granulomatous colitis in rats

Although increased expression of mucosal addressin cell adhesion molecule‐1 (MAdCAM‐1) has been demonstrated in inflammatory sites of various diseases, its role in colitis remains unknown. In this study, we examined whether MAdCAM‐1 is involved in the pathogenesis of granulomatous colitis induced by peptidoglycan‐polysaccharide (PG‐PS). Experimental colitis was induced by intramural injection of PG‐PS to rat colon. After 3 weeks the colon was removed and the mucosal inflammation was assessed. The area of MAdCAM‐1‐positive venules and the subsets of infiltrating cells were determined in colonic mucosa by immunohistochemistry. In another experiment, monoclonal antibody against MAdCAM‐1 was administered intraperitoneally to examine its attenuating effect on colitis. The intramural injection of PG‐PS induced significant colonic inflammation with granuloma formation. The submucosa was drastically thickened with the infiltration of CD4 positive lymphocytes and ED‐1 positive macrophages. Intense MAdCAM‐1 expression was observed on endothelium of the submucosal venules in inflamed mucosa. Administration of anti‐MAdCAM‐1 antibody significantly attenuated the PG‐PS‐induced colonic damage and cell infiltration. Enhanced expression of MAdCAM‐1 was demonstrated in venular endothelium of the inflamed colon in PG‐PS‐induced colitis. The attenuating effect of anti‐MAdCAM‐1 suggests the importance of the MAdCAM‐1‐dependent process in the formation of chronic granulomatous colitis.

Role of inducible nitric oxide synthase in dextran sulphate sodium‐induced colitis

Background: Different authors have postulated both toxic and protective effects for nitric oxide (NO) in the pathophysiology of active inflammation.

Role of nociceptin/orphanin FQ (Noc/oFQ) in murine experimental colitis.

Nociceptin/orphanin (Noc/oFQ), endogenous agonist for nociceptin receptor (NOR), is thought to be a stimulator of neurogenic inflammation. We investigated the possible role of Noc/oFQ in the development of colitis using NOR-deficient mice treated with dextran sulfate sodium (DSS). Colitis was significantly improved in NOR-deficient mice against wild-type mice. Expression level of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) and infiltrating cells also significantly decreased in NOR-deficient mice against wild-type mice. Nociceptin expression increased in wild-type mice after DSS treatment. These results suggest stimulation by Noc/oFQ deteriorates colonic inflammation via up-regulation of adhesion molecule.

Differential expression of CCR5 and CRTH2 on infiltrated cells in colonic mucosa of patients with ulcerative colitis

Background and Aim:  The pathogenesis of ulcerative colitis (UC) is unclear, but abnormal infiltration of T lymphocytes in the colonic mucosa has been implicated in the mucosal tissue damage. The abnormal cytokine production because of a T helper (h)1/Th2 imbalance may play an important role in continuing inflammation in the colonic mucosa. In the present study, the expression of chemokine receptor 5 (CCR5) as a Th1 marker and a chemoattractant receptor‐homologs molecule expressed on Th2 cells (CRTH2) were investigated in order to analyze impaired Th1/Th2 responses in the colonic mucosa of UC patients.

Activation of microvascular endothelial cells in active ulcerative colitis and detection of inducible nitric oxide synthase.

Endothelial nitric oxide (NO) synthase (NOS) that is expressed constitutively on microvascular endothelium is believed to be essential to systemic and/or local vascular integrity. Endothelial cells (ECs) were reported to express inducible NOS (iNOS) under some conditions iNOS expression indicates vascular activation. In this study we examined microvascular activation using ECs obtained from patients with ulcerative colitis (UC). We cultured ECs from the mesenteries of surgical UC patients and assayed NOS activity by NADPH-diaphorase cytochemistry and immunocytochemistry with an anti-iNOS antibody. Strong NOS activity was demonstrated on the cells from UC patients (5/5), whereas no activity was detected on the cells from cancer patients and human umbilical vein endothelial cells (HUVEC 0/5, 0/5). Strong iNOS activity was detected by immunoreaction, and large amounts of NO generated were detected by the conversion from [14C]arginine to [14C]citrulline (HUVEC 624+/-376 vs. EC-UC 1,492+/-233 dpm). These results suggest the possibility that ECs express spontaneous and continuous iNOS in active UC. They indicate a close relationship of vascular activation with the pathogenesis of UC.

Increased pentosidine, an advanced glycation end-product, in urine and tissue reflects disease activity in inflammatory bowel diseases.

Background:  Under inflammatory conditions with strong oxidative stresses, advanced glycation end‐products (AGE), carbonyl compounds, are produced. The concentration of pentosidine, an AGE, reportedly correlates with complications of diabetes mellitus and worsening of rheumatoid arthritis, but its role in the pathogenesis of inflammatory bowel diseases (IBD) is unclear.

TWO CASES OF INFLAMMATORY BOWEL DISEASE WITH MULTIPLE MYELOMA

Abstract: A significant increase has been reported in reticuloendothelial neoplasms in patients with inflammatory bowel diseases. We present two rare cases of multiple myeloma in patients with inflammatory bowel diseases. One was in a 58-year-old woman with ulcerative colitis, and the other was in a 59-year old woman with Crohns disease. In both patients, multiple myeloma occurred during long-term observation of inflammatory bowel disease and during the inactive stage of intestinal inflammation. The multiple myeloma appeared to have resulted from monoclonal gammopathy of undertermined significance in both patients, and was diagnosed by characteristic serum and bone marrow findings. Our findings suggested that multiple myeloma should be particularly considered in women of middle or advanced age with ulcerative colitis or Crohns colitis and serum monoclonal gammopathy.

Reduced sensitivity of inducible nitric oxide synthase-deficient mice to chronic colitis

BACKGROUND Overproduction of nitric oxide by the inducible form of nitric oxide synthase (iNOS) has been implicated in colitis. Different authors have postulated both toxic and protective effects of nitric oxide (NO) in the pathophysiology of active inflammation. The objective of this study was to examine the role of iNOS in experimental chronic colitis using iNOS-deficient mice. METHODS For induction of colitis, mice received three cycles of 2% of dextran sodium sulfate (DSS) (M.W. 40,000) treatment in drinking water. The degree of colonic inflammation, leukocyte infiltration, and the expression of cell adhesion molecules were determined. INOS expression and nitrotyrosine were also determined by immunohistochemistry. RESULTS After DSS treatment, a moderate colitis with marked cell infiltration was observed. Intense expression of iNOS was observed on infiltrating cells as well as on the colonic mucosal epithelium in these animals. In the iNOS-deficient mice, tissue damage was significantly diminished. No iNOS or nitrotyrosine staining was found in iNOS-deficient mice. The number of infiltrating cells and the expression of mucosal adressin cell adhesion molecule-1 were significantly attenuated in the DSS-treated colon of iNOS-deficient mice. CONCLUSION Induction of iNOS seems to act as a critical toxic effector molecule in the pathogenesis of chronic colonic inflammation.