目的：探讨骨髓间充质干细胞（ MSCs ）在体外对重度哮喘患儿外周血辅助性T细胞17（ Th17）和CD4＋CD25＋调节性T细胞（Treg）的免疫调节作用。方法：体外分离、培养和鉴定MSCs。 MSCs经丝裂霉素处理后按不同比例（1∶1、1∶2、1∶10和1∶20）与哮喘患儿外周血T淋巴细胞（TLC）直接接触共培养，检测各组MSCs 对TLC的增殖调节作用。选取上述1∶2比例共培养体系和单独TLC培养体系，ELISA法分别检测Th17的效应分子白细胞介素17（ IL-17）和Treg效应分子转化生长因子β（ TGF-β）水平，qRT-PCR法检测转录因子维甲酸相关孤儿核受体（RORC）及叉头框蛋白3（Foxp3）mRNA表达水平。结果： MSCs 可显著抑制重度哮喘患儿TLC增殖，且随着MSCs数量的增加，抑制作用增强。 MSCs ＋TLC共培养组Th17转录因子RORC mRNA和效应因子IL-17表达较TLC组下降，同时TGF-β表达增高，而Treg细胞调控基因Foxp3 mRNA表达无明显改变。结论： MSCs在体外可能通过抑制Th17分化及IL-17的分泌，同时上调TGF-β的表达，进而有效改善哮喘患儿的Th17/Treg失衡状态。%AIM: To investigate the regulatory function of bone marrow-derived mesenchymal stem cells (MSCs) on T helper 17 cells (Th17) and regulatory T cells (Treg) in peripheral blood of severe asthmatic children . METHODS:MSCs were isolated , cultured and identified in vitro.MSCs digested with mitomycin were cocultured with T lymphocytes (TLC) at different ratios (1∶1, 1∶2, 1∶10 and 1∶20) from severe asthmatic children for 72 h.The prolifera-tion of TLC was measured by CCK-8 method.In the coculture system of the 1∶2 ratio and the single TLC system , the super-natant levels of interleukin-17 (IL-17) and transforming growth factor-β(TGF-β) were measured by ELISA.The mRNA expression of retinoic acid-related orphan nuclear receptor C (RORC) and forkhead box protein 3 (Foxp3) in TLC was de-tected by qRT-PCR.RESULTS:After cocultured with MSCs , the proliferation of TLC decreased significantly in a dose-dependent manner (P<0.05).It also showed decreases in IL-17 (3 799 ±441 vs 4 890 ±373, P<0.05) and RORC mRNA level (1.21 ±0.14 vs 3.85 ±0.48, P<0.05), while an increase in TGF-βlevel (209 ±32 vs 117 ±26, P<0.05) was observed.No influence on the mRNA expression of Foxp3 was found (P>0.05).CONCLUSION: MSCs suppresses Th17 polarization of naive peripheral blood CD 4 +T cells and matures Th17 cells secreting IL-17, which may ef-fectively revise Th17/Treg imbalance of asthma .
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