The effect of proteasome inhibitor MG132 on experimental inflammatory bowel disease.

Immunoproteasome up-regulation enhances the processing of nuclear factor-kappaB (NF-kappaB) and degradation of IkappaBalpha, which correlates with increased amounts of NF-kappaB in the various cells. Aberrant activation of NF-kappaB is involved in the pathogenesis of inflammatory bowel disease (IBD). The aim of this study was to elucidate the effect of proteasome inhibitor MG132 on experimental IBD. We investigated the effects of MG132 on intestinal inflammation and epithelial regeneration in both interleukin-10-deficient (IL-10(-/-)) mice and mice with dextran sulphate sodium (DSS)-induced colitis. Body weight, histological findings and tumour necrosis factor (TNF)-alpha mRNA expression, epithelial cell proliferation and NF-kappaB p65 activity in colonic tissues were examined. The effects of MG132 on cell proliferation, migration and multiple drug resistance 1 (MDR1) gene expression were determined in vitro. MG132 ameliorated intestinal inflammation of IL-10(-/-) mice by decreasing TNF-alpha mRNA expression in the colonic tissues, which was associated with suppression of NF-kappaB activation, and reduced significantly the number of Ki-67-positive intestinal epithelial cells. On the other hand, MG132 did not reduce intestinal inflammation in mice with DSS-induced colitis, and delayed significantly the recovery of body weight and epithelial regeneration. MG132 also suppressed significantly epithelial cell proliferation, cell migration and MDR1 gene expression in vitro. Proteasome inhibition reduces T cell-mediated intestinal inflammation, but may interrupt both epithelial regeneration and barrier function of colonic mucosa. Optimal use of proteasome inhibitor should be kept in mind when we consider its clinical application for patients with IBD.

Long-term effect of tacrolimus therapy in patients with refractory ulcerative colitis.

BACKGROUND: Little is known about long-term outcome of tacrolimus therapy for ulcerative colitis. Aim To evaluate long-term efficacy and safety of tacrolimus in Japanese patients with refractory ulcerative colitis. METHODS: Twenty-seven patients with UC refractory to conventional therapy were administered tacrolimus with trough whole-blood levels of 10-15 ng/mL to induce remission and 5-10 ng/mL to maintain remission. Median treatment duration was 11 months (1-39 months) and median follow-up duration was 17 months (2-65 months). Evaluation of the clinical response was based on a modified Truelove-Witts severity index (MTWSI). RESULTS: Tacrolimus produced a clinical response in 21 patients (77.8%), and remission was achieved in 19 of these 21 (70.4%) within 30 days. Overall cumulative colectomy-free survival was estimated as 62.3% at 65 months. In 18 of 19 patients treated with corticosteroids at the initiation of tacrolimus therapy, corticosteroids were discontinued or tapered. Adverse events were tremor (25.9%), renal function impairment (18.5%), infectious disease (14.8%), hot flashes (11.1%), hyperkalaemia (7.4%), headache (7.4%), epigastralgia (7.4%) and nausea (3.7%). No mortality occurred. CONCLUSION: Long-term administration of tacrolimus appears to be an effective and well-tolerated treatment for Japanese patients with refractory ulcerative colitis.

Gastric mucosal hyperplasia via upregulation of gastrin induced by persistent activation of gastric innate immunity in major histocompatibility complex class II deficient mice.

BACKGROUND AND AIMS: Major histocompatibility complex class II deficient (Aalpha0/0) mice have decreased CD4+ T cells, making them immunologically similar to patients with acquired immunodeficiency syndrome (AIDS). Both patients with AIDS and Aalpha0/0 mice have hypertrophic gastric folds. To clarify the mechanism of gastric mucosal hyperplasia, we investigated the pathophysiology and the role of the innate immunity in the stomach of Aalpha0/0 mice. METHODS: Stomachs from 1-6 month old Aalpha0/0 mice, kept under specific pathogen free conditions, were examined at 1 month intervals histologically and immunohistochemically. Gene expression of proinflammatory cytokines, Toll-like receptors (TLRs), cyclooxygenase (COX)-2, and myeloperoxidase (MPO) activity in the gastric mucosa was investigated. Serum gastrin levels and gastric acidity were measured. Bacterial culture of the stomach was performed. To clarify the roles of hypergastrinaemia in the gastric mucosa, a gastrin receptor antagonist (AG041R) was administered. RESULTS: Aalpha0/0 mice had a diffusely thick corpus mucosa with infiltration of CD11b+ granulocytes and macrophages. Anti-Ki67 staining demonstrated expansion of the proliferating neck zone. Gene expression of interleukin 1beta, interferon gamma, TLR-2, TLR-4, and COX-2 were upregulated, and MPO activity was increased. Only a small amount of non-pathogenic bacteria was detected in the stomach. Serum gastrin levels and Reg-Ialpha positive cells in the gastric mucosa increased, despite normal gastric acidity. After treatment with AG041R, gastric mucosal thickness was significantly reduced. CONCLUSION: Persistent activation of innate immunity in the stomach induced gastric mucosal hyperplasia through upregulation of gastrin synthesis in Aalpha0/0 mice, suggesting a pathophysiology similar to the gastric changes in patients with AIDS.