Extracellular vesicles produced by bone marrow mesenchymal stem cells overexpressing programmed death-ligand 1 ameliorate dextran sodium sulfate-induced ulcerative colitis in rats by regulating Th17/Treg cell balance through PTEN/PI3K/AKT/mTOR axis.

BACKGROUND AND AIM: Programmed death-ligand 1 (PD-L1) was involved in regulating Th17/Treg cell balance in ulcerative colitis (UC). Extracellular vesicles (EVs) from genetically modified bone marrow mesenchymal stem cells (BMSCs) can serve as a stable delivery system to overexpress PD-L1. The study was designed to evaluate the therapeutic mechanism of BMSC-EVs overexpressing PD-L1 (PD-L1-EVs) on ulcerative colitis. METHODS: Experimental model of UC was established in rats by drinking 5% dextran sulfate sodium (DSS). Apoptosis-related proteins, inflammatory response-related factors and oxidative stress related mediators were detected. Westernblot was used to detecte key proteins in the PI3K/AKT signaling pathway and its downstream effectors. The CD4+ Foxp3+ Treg cells and CD4+ IL-17A+ Th17 cells in spleen and mesenteric lymph nodes (MLNs) was detected by flow cytometry. RESULTS: PD-L1-EVs significantly alleviated the manifestations and pathological damage of UC rats by inhibiting the expression of IFN-γ, IL-1ß, IL-8, IL-6, IL-2, BAX, NF-κB, TNF-α, MPO, and MDA, and up-regulating the expression of IL-4, BCL-2, SOD, and GSH. Furthermore, the proportions of Th17 cells were decreased and that of Treg cells were upregulated by PD-L1-EVs treatment. PTEN inhibitors (bpv) partially abolished the inhibitory effect of PD-L1-EVs on PI3K-AKT signaling and impaired the therapeutic efficacy of PD-L1-EVs. CONCLUSIONS: PD-L1-EVs mitigated colonal inflammation, apoptosis and oxidative stress through blocking the activation of PI3K/Akt/mTOR pathway and regulating the balance of Th17/Treg cells.

JMJD3/H3K27me3 epigenetic modification regulates Th17/Treg cell differentiation in ulcerative colitis.

Ulcerative colitis (UC) is a chronic nonspecific inflammatory bowel disease characterized by chronic inflammation and ulceration of the colonic mucosa, frequent relapse, and cancerization that is difficult to cure. In recent years, the incidence of UC has increased. However, its etiology and pathogenesis are still not completely clear. In this study, dextran sodium sulfate (DSS) was used to induce the model, and GSK-J1 and dexamethasone were administered to the mice. A variety of molecular biology and immunological techniques, such as immunofluorescence, PCR and chromatin immunoprecipitation (ChIP), were used to examine JMJD3/H3K27me3-mediated regulation of Th17/Treg cell differentiation in UC by targeting histone modification. This study will provide an important theoretical basis for understanding the pathogenesis and potential therapeutic targets of UC.

Compound sophorae decoction enhances intestinal barrier function of dextran sodium sulfate induced colitis via regulating notch signaling pathway in mice.

BACKGROUND: Compound sophorae decoction (CSD), a Chinese Herbal decoction, is frequently clinically prescribed for patients suffered from ulcerative colitis (UC) characterized by bloody diarrhea. Yet, the underlying mechanism about how this formulae works is remain elusive. METHODS: In the present study, the experimental colitis in C57BL/6 J mice was induced by oral administration of standard diets containing 3% dextran sodium sulfate (DSS), and CSD was given orally for treatment at the same time. The clinical symptoms including stool and body weight were recorded each day, and colon length and its histopathological changes were observed. Apoptosis of colonic epithelium was studied by detecting protein expression of cleaved caspase-3, and cell proliferation by Ki-67 immunohistochemistry. Tight junction complex like ZO-1 and occludin were also determined by transmission electron microscope and immunofluorescence. The concentration of FITC-dextran 4000 was measured to evaluate intestinal barrier permeability and possible signaling pathway was investigated. Mucin2 (MUC2) and notch pathway were tested through western blot. The M1/M2 ratio in spleen and mesenteric lymph nodes were detected by flow cytometry. And the mRNA levels of iNOS and Arg1 were examined by qRT-PCR. RESULTS: CSD could significantly alleviate the clinical manifestations and pathological damage. Body weight loss and DAI score of mice with colitis were improved and shortening of colon was inhibited. The administration of CSD was able to reduce apoptotic epithelial cells and facilitate epithelial cell regeneration. Increased intestinal permeability was reduced in DSS-induced colitis mice. In addition, CSD treatment obviously up-regulated the expression of ZO-1 and occludin and the secretion of MUC2, regulated notch signaling, and decreased the ratio of M1/M2. CONCLUSIONS: These data together suggest that CSD can effectively mitigate intestinal inflammation, promote phenotypic change in macrophage phenotype and enhance colonic mucosal barrier function by, at least in part, regulating notch signaling in mice affected by DSS-induced colitis.