Endothelial nitric oxide (NO) synthase, a unique NO synthase (NOS) isoform that is expressed constitutively by the vascular endothelium both in vivo and in vitro, is believed to be essential to systemic and/or local vascular integrity. NOS expression by endothelial cells may indicate vascular activation. We successfully established a simple method for the culture of microvascular endothelial cells from a small amount of tissue and investigated ulcerative colitis (UC), in which condition vascular factors have not been studied extensively. We cultured endothelial cells from the mesenteries of surgical patients with UC and assayed NOS activity by reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemistry. Strong NOS activity was demonstrated in the cells from all UC patients (5/5), whereas no activity was detected in the cells from human umbilical veins and the mesenteries of colon cancer patients (0/10 and 0/5, respectively). This strong NOS activity was not diminished by incubation with a high concentration of glucocorticoid, suggesting that it was constitutive. These results indicate a close relationship of vascular activation (high NOS activity) with the pathogenesis of UC.

Depletion of granulocytes and monocytes (GM) by selective apheresis (GMA) with an Adacolumn exerts an anti-inflammatory effect in patients with ulcerative colitis (UC) or rheumatoid arthritis. However, the mechanism of the anti-inflammatory effect of GMA is not fully understood yet. We investigated the effect of GMA on the plasma concentration of interleukin-1 receptor antagonist (IL-1ra), a potent anti-inflammatory cytokine. Twenty-six patients with active UC received GMA at one session per week for 5 consecutive weeks. Clinical response was defined as Deltaclinical activity index (DeltaCAI=CAI at entry - CAI at post)>or=4, while clinical remission was defined as CAI

Although current nitric oxide (NO) electrodes are simple, selective and sensitive, they are fragile and hard to use in clinical studies of patients. By preparing an improved NO electroneedle that overcomes these defects, we directly measured mucosal NO concentrations in 11 patients (six male, five female; mean 26.0 years old) with ulcerative colitis (UC) and five normal volunteers (three male, two female; mean 28.3 years old) in situ. An electroneedle was inserted into colonic mucosa through a biopsy channel during colonoscopy. The information concerning the concentration of NO generated and the appearances of the colonic mucosa at the same site were obtained simultaneously. In the ulcerative colitis patients, NO concentrations were significantly increased at all 24 mucosal sites tested. These included sites where: there was an absence of visible inflammation (five sites); the mucosa was mildly inflamed (eight sites); the mucosa was moderately inflamed (five sites); or severely inflamed (six sites). The NO concentrations in ulcerative colitis patients were 12-72 times higher than the NO levels in normal controls (10 sites). At the same 10 sites in four ulcerative colitis patients, the high NO concentrations were decreased by 53% after glucocorticoid treatment. These data are consistent with those of previous studies utilizing different NO electrodes. Excess mucosal NO is generated from inducible NO synthase in the inflamed mucosa itself and the invading inflammatory cells. Our results suggested that mucosal NO could be a marker for the extent of inflammation and its various actions correlated with the pathogenesis, natural history and prognosis of UC. Using the NO microelectrode system reported here, the concentration of NO generated can be monitored in real-time while observing the mucosal condition at the same site during endoscopy. This novel NO electrode may contribute to understanding the role of NO in colonic mucosal inflammation.

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