Ulcerative Colitis: Itoh J

Kikuchi H, Itoh J, Fukuda S. · Department of Gastroenterology and Hematology, Hirosaki University School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, Japan. · Neurosci Lett. · Pubmed #18248893 No free full text.

Abstract: Inflammatory bowel disease (IBD) consists of Crohn's disease (CD) and ulcerative colitis (UC). The etiology has not been clarified yet, but immune disorder is thought to be involved in the pathogenic physiology. Recently, general consensus has been reached that CD and UC are distinct, especially in respect of the immune response. Interestingly, smoking has diverse effects on CD, Th1-type enteritis, and on UC, Th2-type. However, the mechanisms remain obscure. Therefore, we hypothesized that nicotine altered the distinct immune responses in each form of IBD to affect their pathophysiology. In this study, we first demonstrated by RT-PCR analysis that human lamina propria T (LPT) cells had nicotinic acetylcholine receptor (nAChR), and express alpha7 nAChR subunit universally. In addition, the expression of T-bet mRNA in human LPT cells was significantly upregulated after the culture with 10(-7)M and 10(-5)M nicotine for 9 days, while chronic nicotine stimulation showed negligible effect on the expression of GATA-3 mRNA by real-time PCR. The effect of nicotine was inhibited by mecamylamine (MEC). These results suggested that nicotine could modulate the immune balance to Th1-dominant via nAChR in the intestine, to improve Th2-type enteritis. This may provide the experimental evidence for the fact that nicotine has a beneficial influence on UC, and exacerbates CD. Furthermore, it is of great interest that nicotine acts oppositely on CD and UC by modulation of the mucosal immune balance via the neurotransmitter receptor.

Katz JA, Itoh J, Fiocchi C. · Division of Gastroenterology, University Hospitals of Cleveland, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA. · Curr Opin Gastroenterol. · Pubmed #17023960 No free full text.

Abstract: In spite of expanding knowledge of cellular and molecular mechanisms of intestinal inflammation, the etiology and pathogenesis of inflammatory bowel disease (IBD) remain obscure. The link between the environment and IBD is still circumstantial, but definite progress is occurring in defining genetic susceptibility loci for Crohn's disease (CD) and ulcerative colitis (UC). The notion that normal enteric flora play a role in initiating or maintaining IBD is gaining momentum. Some components of the flora may act as noxious agents, whereas others (probiotics) seem to have a protective effect. The importance of the mucosal immune system to IBD is established, and evidence is accumulating that nonimmune components, such as epithelial, mesenchymal, and endothelial cells, also contribute to gut inflammation. The effect of cytokines in intestinal immunity is being elucidated by studies on their molecular mechanism, particularly the activation of nuclear factor (NF)-kappaB. Finally, the beneficial effects of cytoprotective prostaglandins and cell adhesion molecule (CAM) blockade promise novel therapeutic opportunities derived from an improved understanding of IBD pathogenesis.

Itoh J, de La Motte C, Strong SA, Levine AD, Fiocchi C. · Division of Gastroenterology, University Hospitals of Cleveland, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA. · Gut. · Pubmed #11413108 links to  free full text

Abstract: BACKGROUND: Activated T cells are more susceptible to apoptosis than resting T cells. As intestinal T cells normally exhibit a higher state of activation, increased apoptosis may be necessary to maintain immune homeostasis in the specialised microenvironment of the mucosa. On the other hand, in Crohn's disease (CD) mucosal T cells are resistant to apoptosis, suggesting abnormal regulation of cell death mechanisms. AIMS: To investigate differences in expression of anti- and proapoptotic Bcl-2 family proteins, key regulators of apoptosis, between circulating and mucosal T cells, and possible alterations in CD. PATIENTS AND METHODS: Lamina propria T cells (LPT) were isolated from 10 control, seven CD, and eight ulcerative colitis (UC) patients, and peripheral blood T cells (PBT) from healthy volunteers. Purified T cells were stained intracellularly for Bcl-2, Bcl-x(L), and Bax, and mean fluorescence intensity measured by flow cytometry. RESULTS: Compared with PBT, the expression level of Bcl-2 and Bax, but not Bcl-x(L), was significantly greater in LPT, resulting in lower Bcl-x(L)/Bax ratios. In PBT, Bax expression was highly and significantly correlated with both Bcl-2 and Bcl-x(L), but correlation with Bcl-2 was absent in LPT. Bax expression in CD, but not UC, LPT was significantly lower than in control LPT, resulting in a significantly higher Bcl-x(L)/Bax ratio. The significant correlation of Bcl-x(L) to Bax was preserved in CD, but not UC, LPT. CONCLUSIONS: Regulation of Bcl-2 family protein expression differs between circulating and mucosal T cells, probably underlying diverse survival potentials. In CD LPT, a low Bax expression and a high Bcl-x(L)/Bax ratio favour resistance to apoptosis and may contribute to the chronicity of inflammation.

Ina K, Itoh J, Fukushima K, Kusugami K, Yamaguchi T, Kyokane K, Imada A, Binion DG, Musso A, West GA, Dobrea GM, McCormick TS, Lapetina EG, Levine AD, Ottaway CA, Fiocchi C. · Division of Gastroenterology, Molecular Cardiovascular Research Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA. · J Immunol. · Pubmed #10395708 links to  free full text

Abstract: Crohn's disease (CD) is a condition characterized by excessive numbers of activated T cells in the mucosa. We investigated whether a defect in apoptosis could prolong T cell survival and contribute to their accumulation in the mucosa. Apoptotic, Bcl-2+, and Bax+ cells in tissue sections were detected by the TUNEL method and immunohistochemistry. T cell apoptosis was induced by IL-2 deprivation, Fas Ag ligation, and exposure to TNF-alpha and nitric oxide. TUNEL+ leukocytes were few in control, CD, and ulcerative colitis (UC) mucosa, with occasional CD68+ and myeloperoxidase+, but no CD45RO+, apoptotic cells. Compared with control and UC, CD T cells grew remarkably more in response to IL-2 and were significantly more resistant to IL-2 deprivation-induced apoptosis. CD T cells were also more resistant to Fas- and nitric oxide-mediated apoptosis, whereas TNF-alpha failed to induce cell death in all groups. Compared with control, CD mucosa contained similar numbers of Bcl-2+, but fewer Bax+, cells, while UC mucosa contained fewer Bcl-2+, but more Bax+, cells. Hence, the Bcl-2/Bax ratio was significantly higher in CD and lower in UC. These results indicate that CD may represent a disorder where the rate of T cell proliferation exceeds that of cell death. Insufficient T cell apoptosis may interfere with clonal deletion and maintenance of tolerance, and result in inappropriate T cell accumulation contributing to chronic inflammation.