Shi Ganggang, Wang Grace, Lu Shanzheng, Li Xiang, Zhang Baoren, Xu Xiaoxi, Lan Xu, Zhao Yiming, Wang Hao
Department of General Surgery, Tianjin Medical University General Hospital Tianjin, China.
Tianjin General Surgery Institute Tianjin, China.
Am J Transl Res. 2019 Aug 15;11(8):4696-4712. eCollection 2019.
Endometrial regenerative cells (ERCs) are easily isolated from menstrual blood, and can be cultured in large amounts. Although, ERCs can ameliorate DSS-induced colitis in mice, the molecular mechanism underlying ERCs-mediated immunosuppression is unclear. This study was aimed to assess the function of PD-L1 expressed on ERCs in colitis attenuation. ERCs with and without anti-PD-L1 mAb-pretreatment were administered to mice by injection at 2, 5 and 8 days after colitis induction by DSS treatment. Blood, spleen and colon samples were obtained 15 days post-DSS-induction. Then, clinicopathological alterations, cytokine levels, immune cell types and cell tracking were assessed. ERCs or ERCs preincubated with anti-PD-L1 antibody were co-cultured with splenocytes, whose phenotypes was analyzed by flow cytometry. We found that PD-L1 on ERCs was upregulated by IFN-γ stimulation. The transplanted PKH26-labeled ERCs were engrafted to the lung, liver, spleen and injured colon. Interestingly, ERC-based therapy markedly attenuated mouse colitis, but blockade of PD-L1 on ERCs with a specific monoclonal antibody conferred severe colitis to the animals. These effects of PD-L1 inhibition on colitis were associated with reduced amounts of pro-inflammatory cytokines and infiltrated immune cells, including CD3CD4 T lymphocytes, CD3CD8 T lymphocytes, CD11cMHC-II Dendritic cells and F4/80 macrophages, both in vivo and in vitro, as well as with elevated levels of anti-inflammatory cytokines and regulatory immune cells, including CD4CD25Foxp3 Tregs and F4/80CD206 macrophages. These findings demonstrated that ERCs-based treatment promotes immune tolerance in mouse colitis, in association with PD-L1, thus indicating that PD-L1 modulates immunosuppression by ERCs.
子宫内膜再生细胞（ERCs）易于从月经血中分离出来，并且能够大量培养。尽管ERCs可以改善小鼠中由葡聚糖硫酸钠（DSS）诱导的结肠炎，但其介导免疫抑制的分子机制尚不清楚。本研究旨在评估ERCs上表达的程序性死亡受体配体1（PD-L1）在减轻结肠炎中的作用。在DSS诱导结肠炎后的第2、5和8天，通过注射将经抗PD-L1单克隆抗体预处理和未预处理的ERCs给予小鼠。在DSS诱导后15天获取血液、脾脏和结肠样本。然后，评估临床病理改变、细胞因子水平、免疫细胞类型和细胞追踪情况。将ERCs或与抗PD-L1抗体预孵育的ERCs与脾细胞共培养，通过流式细胞术分析其表型。我们发现，IFN-γ刺激可上调ERCs上的PD-L1。移植的PKH26标记的ERCs可植入肺、肝、脾和受损结肠。有趣的是，基于ERCs的治疗显著减轻了小鼠结肠炎，但用特异性单克隆抗体阻断ERCs上的PD-L1会使动物患上严重结肠炎。PD-L1抑制对结肠炎的这些作用与体内和体外促炎细胞因子及浸润免疫细胞数量减少有关，这些免疫细胞包括CD3CD4 T淋巴细胞（辅助性T细胞）、CD3CD8 T淋巴细胞（细胞毒性T细胞）、CD11cMHC-II树突状细胞和F4/80巨噬细胞，同时也与抗炎细胞因子及调节性免疫细胞水平升高有关，这些细胞包括CD4CD25Foxp3调节性T细胞（Tregs）和F4/80CD206巨噬细胞。这些发现表明，基于ERCs的治疗与PD-L1共同促进小鼠结肠炎中的免疫耐受，从而表明PD-L1调节ERCs介导的免疫抑制。
