ABSTRACT
The present study is designed to explore the role of plasma cells in the change of protein C system (PCS) in ulcerative colitis (UC). Dextran sulfate sodium (DSS, 4% in concentration) was used to induce mouse UC model. The plasma cells and the type of immune complex in colon were observed by immunofluorescence. The amount and type of plasma cells separated from colonic mucosal lamina propria were detected by flow cytometry using anti-CD54CD38and IgA/M/G antibodies, respectively. After stimulation of macrophages by IgG type immune complex, TNF-α and IL-6 levels were evaluated by ELISA. After co-incubation of microvascular endothelial cells with TNF-α or IL-6, the expressions of endothelial protein C receptor (EPCR) and thrombomodulin (TM), and the activity of activated protein C (APC) were examined. As the results showed, the IgG type plasma cells infiltration and the quantity of IgG type immune complex were increased in DSS group in comparison with control group. After incubation with IgG type immune complex, the levels of TNF-α and IL-6 in the supernatant of macrophages were increased (P < 0.01) in a concentration-dependent manner. Meanwhile, after incubation with TNF-α or IL-6, the expressions of EPCR and TM in the microvascular endothelial cells were decreased (P < 0.05 or P < 0.01), while the activity of APC was reduced (P < 0.05 or P < 0.01). These results suggested that the quantity of IgG type plasma cells increases in UC and forms immune complexes, which affect the secretion of cytokines from macrophage, thereby affecting the function of endothelial cells and finally inhibiting PCS in UC. Therefore, plasma cell may be a novel target for the treatment of UC.
ABSTRACT
Long term peritoneal dialysis (PD) is often associated with peritoneal fibrosis. The aim of this study was to explore the effect of emodin on PD-related peritoneal fibrosis and its related cellular and molecular mechanism. PD-related peritoneal fibrosis rats and cultured rat peritoneal mesothelial cells were recruited in the experiment. PD-related peritoneal fibrosis was induced by intraperitoneal injection of lactate-buffered solution containing 4.25% glucose. The peritoneal equilibrium test (PET) was performed at the end of 2 weeks, 4 weeks, and 6 weeks, respectively. HE staining and Masson staining were used for histopathological evaluation. Enzyme linked immunosorbent assay (ELISA) was used to measure the plasma N-terminal procollagen III propeptide (PIIINP) level. Real-time PCR technique was used to detect the mRNA levels of Notch1, Jagged-1, and Hes-1 in peritoneal tissue. Western blot was applied to identify the protein levels of Notch1, Jagged-1, Hes-1, and Notch intracellular domain (NICD). In vitro, Notch1 overexpressing or knockdown rat peritoneal mesothelial cells were established and Western blot was used to examine the effect of emodin on the expressions of Hes-1 and Hey. Compared with the control group, HE staining revealed that PD rats suffered from decreasing in mesothelial cells, or detaching from surface of parietal peritoneum, accompanied by infiltration of inflammatory cells; Masson staining result showed thickened peritonea (P < 0.01), and the collagen deposition in the parietal peritoneum was increased; also, PIIINP level in plasma was elevated (P < 0.01). Treatment of the PD rats with emodin increased mesothelial cells in peritoneal tissue, and decreased the peritoneal thickness (P < 0.01), collagen depositions, as well as the plasma PIIINP level (P < 0.05). The expressions of Notch1, Jagged-1, Hes-1 and NICD in peritoneal tissue were also attenuated (P < 0.05 or P < 0.01). In cultured rat peritoneal mesothelial cells, compared with emodin group, emodin further inhibited the expressions of Hes-1 and Hey induced by Notch1-overexpression (P < 0.05), but not the expressions of Hes-1 and Hey induced by Notch1-knockdown (P > 0.05). Therefore, the activation of Notch pathway may be involved in the pathological process of PD-induced peritoneal fibrosis. Emodin may ameliorate the PD-related peritoneal fibrosis through inhibiting the activation of Notch pathway.