The MHC class II transactivator (CIITA) is the master transcriptional regulator of genes involved in MHC class II restricted antigen presentation. Previously we suggested another role of CIITA in Th1/Th2 balance by demonstrating that forced expression of CIITA in murine T cells repressed Th1 immunity both in vitro and in vivo. However, the results were contradictory to the report that CIITA functioned to suppress the production of Th2 cytokine by CD4+T cells in CIITA deficient mice. In this study, we investigated the influence of constitutive expression of CIITA in T cells on Th2 immune response in vivo using murine experimental colitis model. In the dextran sodium sulfate-induced acute colitis, a disease involving innate immunity, CIITA transgenic mice and wild type control mice showed similar progression of the disease. However, the development of oxazolone-induced colitis, a colitis mediated by predominantly Th2 immune response, was aggravated in CIITA-transgenic mice. And, CD4+T cells from the mesenteric lymph node of CIITA-transgenic mice treated with oxazolone exhibited a high level of IL-4 secretion. Together, these data demonstrate that constitutive expression of CIITA in T cells skews immune response to Th2, resulting in aggravation of Th2-mediated colitis in vivo.
Trans-Activators/*physiology ; Th2 Cells/*immunology ; T-Lymphocytes/*metabolism ; Oxazolone/pharmacology ; Nuclear Proteins/*physiology ; Mice, Transgenic ; Mice, Inbred C57BL ; Mice ; Interleukin-4/biosynthesis ; Colitis/*etiology ; Animals

Previous studies have demonstrated that the Chinese medicine paeoniflorin, derived from the Ranunculaceae plant peony, peony, purple peony root, was able to have anti-inflammatory, anti-ulcer, anti-hypersusceptibility and anti-oxidation activity. In order to elucidate the pesticide effect and the mechanisms by which paeoniflorin exerts its effect of anti-inflammation and immunoregulation on oxazolone-induced colitic mice, disease activity index (DAI) and histological grading of colitis (HGC) were evaluated in animal model. Moreover, the expressions of HBD-2, IL-6 and IL-10 of mice with experimental colitis were observed with immunohistochemistry and RT-PCR in this study. Results showed that DAI and HGC of oxazolone control group was significantly higher than that of normal control group, and that paeoniflorin groups and 5-ASA group, compared with oxazolone control group, could alleviate the symptoms and histological damages of colitic mice (P < 0.05, P < 0.01). The expression of HBD-2 and IL-6 cytokine on the colon of colitic mice was higher than that of normal control, paeoniflorin and 5-ASA groups (P < 0.05, P < 0.01), but the expression of IL-10 is lower than that of normal control, paeoniflorin and 5-ASA groups (P < 0.05, P < 0.01). The positive correlations were demonstrated between the expression of (HBD-2 and IL-6) and DAI (Pearson r = 0.728, Pearson r = 0.758, P < 0.01, respectively), (HBD-2 and IL-6) and HGC (Pearson r = 0.819, Pearson r = 0.825, P < 0.01, respectively), whereas, the negative correlations were demonstrated between the expression of IL-10 and DAI (Pearson r = -0.789, P < 0.01), IL-10 and HGC (Pearson r = -0.725, P < 0.01). It can be concluded that to some extent paeoniflorin effectively alleviate the symptoms of oxazolone-induced colitis through regulating the expression of HBD-2, IL-6 and IL-10.
Animals ; Anti-Inflammatory Agents, Non-Steroidal ; isolation & purification ; pharmacology ; Benzoates ; isolation & purification ; pharmacology ; Bridged-Ring Compounds ; isolation & purification ; pharmacology ; Colitis ; chemically induced ; drug therapy ; metabolism ; pathology ; Colon ; pathology ; Female ; Glucosides ; isolation & purification ; pharmacology ; Interleukin-10 ; genetics ; metabolism ; Interleukin-6 ; genetics ; metabolism ; Intestinal Mucosa ; pathology ; Mesalamine ; pharmacology ; Mice ; Mice, Inbred BALB C ; Monoterpenes ; Oxazolone ; Paeonia ; chemistry ; RNA, Messenger ; metabolism ; Random Allocation ; beta-Defensins ; genetics ; metabolism