Polydatin Ameliorated Colonic Inflammation via Precluding Phosphorylation of PKCθ/STAT3 Pathway to Inhibit Th17 Cells in Mice with Ulcerative Colitis / 中国实验方剂学杂志

Objective:To investigate the therapeutic effect of polydatin on ulcerative colitis （UC） in mice and its regulation of protein kinase C<italic>θ</italic>（PKC<italic>θ</italic>）/signal transducer and activator of transcription 3（STAT3） signaling on T helper cell 17（Th17） and its mechanism in the treatment of UC. Method:The 32 male C57BL/6 mice were randomly divided into normal group， model group， polydatin group （0.045 g·kg^-1） and sulfasalazine group （0.5 g·kg^-1）. The UC model was established by giving 3% dextran sodium sulfate （DSS） solution to free drinking water in mice. Polydatin and sulfasalazine groups were given by gavage 0.5 h before modeling for 7 days. The normal group and model group were given the same amount of normal saline. After the last administration， the colonic tissue was taken and hematoxylin-eosin （HE） was used to observe the pathological changes of colonic tissue. Flow cytometry was used to detect the proportion of Th17 in the lamina propria of colonic mucosa. The expression of interleukin-17A （IL-17A） in serum was detected by enzyme-linked immunosorbent assay （ELISA）. Polydatin was added to CD4⁺T cells purified from spleen of C57BL/6 mice by magnetic-activated cell sorting （MACS） under the stimulation of cell stimulation cocktail <italic>in vitro </italic>in order to detect its impact on PKC<italic>θ</italic> and STAT3 phosphorylation. Result:Compared with normal group， the body weight was significantly decreased， and disease activity index （DAI） scores of the model group was significantly increased （<italic>P</italic><0.01）， the colonic mucosal epithelium was damaged and inflammatory cells infiltration in the mucosa and submucosa was obvious， the proportion of Th17 in the lamina propria of colonic mucosa was significantly increased （<italic>P</italic><0.01）， and the content of serum IL-17A was significantly increased （<italic>P</italic><0.01）. Compared with the model group， the weight and DAI score of polydatin and sulfasalazine groups were significantly improved （<italic>P</italic><0.01）， the degree of colon tissue damage was significantly improved， the proportion of Th17 in colon mucosa lamina propria was significantly decreased （<italic>P</italic><0.01）， and the content of IL-17A in serum was significantly decreased （<italic>P</italic><0.01）. <italic>In vitro</italic> experiments showed that polydatin could significantly inhibit the phosphorylation of PKC<italic>θ</italic> and STAT3 in Th17 （<italic>P</italic><0.01） as well as IL-17A secretion. Conclusion:Polydatin can improve the ulcerative colitis in mice via inhibiting the phosphorylation of PKC<italic>θ</italic> and STAT3 to preclude IL-17A secreting in Th17.

Role of Citrullinated Fibrinogen Peptides in the Activation of CD4 T Cells from Patients with Rheumatoid Arthritis

This study was conducted to determine whether CD4 T cell responses to citrullinated fibrinogen occur in patients with rheumatoid arthritis (RA), especially in HLA-DR4-positive subjects. Whole peripheral blood mononuclear cells (PBMCs) of RA patients and control subjects were stimulated with citrullinated fibrinogen peptides, and T-cell production of proliferation and proinflammatory cytokines, such as interferon-gamma(IFN-gamma) and interleukin-17A (IL-17A), were measured. In addition, CD4 T cells from RA patients were stimulated with the citrullinated fibrinogen peptide, Fib-alpha R84Cit, identified as a DRB1*0401-restricted T cell epitope in HLA-DR4 transgenic mice, and the degree of T cell activation was examined similarly. No proliferative responses to the citrullinated fibrinogen peptides were observed in whole PBMCs or CD4 T cells from RA patients. Furthermore, no increased production of IFN-gamma or IL-17A was found in whole PBMCs or CD4 T cells stimulated with the citrullinated fibrinogen peptides, although these cells responded to recall antigen, a mixture of tetanus toxoid, purified protein derivative (PPD) from Mycobacterium tuberculosis, and Candida albicans. The results of this study indicate that anti-citrulline immunity in RA patients may be mediated by fibrinogen because there is no evidence of CD4 T cell-mediated immune responses to citrullinated fibrinogen peptides.