Expression of XBP1 in lymphocytes of the small intestine in rats under chronic social stress and modulation of intestinal microflora composition.

The present study was conducted to investigate of the influence of chronic social stress and modulation of the composition of intestinal microflora on the distribution of Xbp(1+)-lymphocytes in the gut-associated lymphoid tissue of ileum of the rats. Structure of population of Xbp(1+)-cells has been studied by the analysis of serial histological sections using the method of indirect immunofluorescence with monoclonal antibodies to Xbp1 of rat. Chronic social stress development is accompanied with the reduction of total number of Xbp(1+)-lymphocytes in lymphoid structures of ileum (31% -3 fold reduction, p < 0.05), mostly expressed in lymphoidfollicles, and changes the concentration of Xbp1 protein in immunopositive cells. Modulation of the composition of intestinal microflora by antibiotics and probiotics under chronic social stress results in the increase of total number of Xbp1+ lymphocytes in gut-associated lymphoid tissue, the degree of it depends on the kind ofstress. The discovered alterations of Xbp1 expression under stress may be one of the triggers for development of autoimmune and inflammatory bowel diseases. Thus, increased understanding of the molecular actions and transcriptional networks regulated by XBP1 in immune cells may aid in the development of potential therapeutics targeting immune disorders.