目的 探讨脐带间充质干细胞（umbilical cord mesenchymal stem cells，UCMSCs）对自身免疫性肝炎（autoimmune hepatitis，AIH）免疫微环境的影响及潜在的调控机制。方法 将 AIH 患者外周血单个 核细胞（PBMCs）与 UCMSCs 分别以 10∶1（Co⁃culture 1）或 5∶1（Co⁃culture 2）的比例共培养。流式细胞术检测 Th17、Treg 及 Th17/Treg 比值；ELISA 检测上清中转化生长因子 β1（TGF⁃β1）、白细胞介素⁃17（IL⁃17）和 IL⁃6 的水平。运用 RNA⁃seq 筛选 PBMCs 共培养前后的差异基因，富集前 15 个表达量最高的 mRNA 进行后 续生物信息分析。Western blot 和 RT⁃qPCR 测定 Foxp3、RORγt 表达水平。结果 UCMSCs 显著降低 CD3+ CD8- IL⁃17A+ Th17 比例，增加 CD25+ Foxp3+ CD4+ Treg 比例。与 PBMCs 组相比，Co⁃culture 2 组的 TGF⁃β1 显著 上调（P < 0.01），IL⁃17和IL⁃6显著下调（P < 0.05）。转录组测序分析发现转录因子主要集中在免疫应答及T细 胞激活等领域；其中 SMAD3 和 STAT3 占据较核心的地位。蛋白和 mRNA 检测显示，Co⁃culture 2 组 Foxp3和 SMAD3 的表达水平显著上调（P < 0.05），RORγt 和 STAT3 的表达水平显著下调（P < 0.05）。结论 UCMSCs 通过TGF⁃β 通路促进Th17向Treg 细胞分化，抑制炎症反应改善肝脏免疫微环境。

Objective To investigate the impact and potential regulatory mechanisms of Umbilical Cord Mesenchymal Stem Cells（UCMSCs）on the immune microenvironment of autoimmune hepatitis（AIH）. Methods Peripheral blood mononuclear cells（PBMCs）from AIH patients co⁃cultured with UCMSCs at a ratio of 10∶1 （Co⁃culture 1）or 5∶1（Co⁃culture 2），respectively. Flow cytometry was used to detect Th17，Treg and Th17/Treg ratio；ELISA was used to detect the levels of transforming growth factor β1（TGF ⁃β1），interleukin ⁃17（IL ⁃17） and IL ⁃ 6 in the supernatant. RNA ⁃ seq was used to screen the differential genes before and after co ⁃ culture of PBMCs，and the top 15 most highly expressed mRNAs were enriched for subsequent bioinformatic analysis. western blot and RT⁃qPCR were used to determine the expression levels of Foxp3 and RORγt. Results UCMSCs significantly decreased CD3+ CD8⁃IL⁃17A+ Th17 ratio and increased CD25+ Foxp3+ CD4+ Treg ratio. Compared with the PBMCs group，TGF⁃β1 was significantly upregulated（P < 0.01）and IL⁃17 and IL⁃6 were significantly downregu⁃ lated（P < 0.05）in the Co ⁃culture 2 group. Transcriptome sequencing analysis revealed that the transcription factors were mainly focused on immune response and T cell activation；among them，SMAD3 and STAT3 occupied a more central position. Protein and mRNA assays showed that the expression levels of Foxp3 and SMAD3 were significantly upregulated in the Co⁃culture 2 group（P < 0.01），and the expression levels of RORγt and STAT3 were significantly downregulated（P < 0.01）. Conclusion UCMSCs promote the differentiation of Th17 to Treg cells through the TGF⁃β pathway，suppress inflammatory responses to improve the hepatic immune microenvironment.