PD-1/PD-L1信号通路通过调控肺泡巨噬细胞参与肺孢子菌感染免疫的机制研究

The incidence of Pneumocystis pneumonia (PCP) is increasing in HIV negative immunosuppressive population. In non-HIV-related PCP（NH-PCP）patients, the mortality of PCP is higher than that in HIV-infected PCP patients. The mechanism involving molecular, signaling pathway and immune cells that mediate the immunity process during Pneumocystis infection is complicated and remains unknown. Our previous study showed that programmed cell death -1 receptor (PD-1)/PD-ligand 1(PD-L1) signaling pathway was significantly upregulated post Pneumocystis infection. Moreover, the lower Pneumocystis load and stronger phagocytosis function of alveolar macrophages were observed in PD-1 knockout PCP mice compared with WT PCP mice. PD-1/PD-L1 signaling pathway plays a pivotal role in malignancy, however, no evidence was reported about PD-1/PD-L1 mediating PCP immunity. We aim to ①illuminate the differentially expressed genes in alveolar macrophage subsets between WT PCP and PD-1 knockout PCP mice via high-throughput sequencing. ②clarify the effect of PD-1/PD-L1 signaling pathway on the immune regulatory mechanism of alveolar macrophages during Pneumocystis infection. ③explore the relationship between PD-1/PD-L1 signaling pathway and clinical characteristics of PCP patients. The study will help to create a better understanding of PCP immunity and provide basic data to the evaluation and treatment of NH-PCP.

HIV阴性的免疫抑制患者肺孢子菌肺炎（PCP）发病率逐年升高，预后差。细胞免疫层面之下，各种分子及信号通路在PCP感染免疫中的作用逐渐受到关注。我们前期研究发现PCP宿主（患者及小鼠）的PD-1/PD-L1通路上调，PCP小鼠肺泡巨噬细胞表面PD-1表达显著增强，且PD-1敲除PCP小鼠的肺泡巨噬细胞吞噬功能增强、对肺孢子菌清除能力显著升高。PD-1/PD-L1信号通路通过调控巨噬细胞参与肿瘤免疫已有报道，但感染免疫领域尤其是PCP领域基本空白。基于此，本项目将：①运用高通量测序技术，明确PD-1敲除的PCP小鼠与WT PCP小鼠不同肺泡巨噬细胞亚群在基因表达谱上的差异；②确定PD-1/PD-L1信号通路对肺泡巨噬细胞的免疫调控机制；③阐明PD-1/PD-L1信号通路与PCP患者临床指标的相关性。本项目将有利于理解PCP感染免疫的分子调控机制，为PCP患者的早期预警及治疗提供新的理论基础。

HIV阴性的免疫抑制患者肺孢子菌肺炎（PCP）发病率逐年升高，预后差。细胞免疫层面之下，各种分子及信号通路在PCP感染免疫中的作用逐渐受到关注。我们前期研究发现PCP宿主（ 患者及小鼠）的PD-1/PD-L1通路上调，PCP小鼠肺泡巨噬细胞表面PD-1表达显著增强，PD-1/PD-L1信号通路通过调控巨噬细胞参与肿瘤免疫已有报道，但感染免疫领域尤其是PCP领域基本空白。本项目通过PD-1敲除小鼠建立PCP动物模型，研究发现，①PD-1 敲除PCP小鼠的肺泡巨噬细胞吞噬功能增强、对肺孢子菌清除能力显著升高，且Th1/Th17等T淋巴细胞免疫增强；②运用高通量测序技术，提示PD-1缺失后趋化因子-趋化因子受体等多条免疫相关通路表达上调，并在分子生物及流式细胞上得到了验证，对后续CXCR3/CXCL9/CXCL10/CXCL11这一趋化因子-趋化因子受体通路对PCP肺泡巨噬细胞的调控研究建立了基础；③多因素回归分析提示PCP患者入院时氧合指数小于200mmHg以及新出现的感染中毒性休克是住院期间死亡的独立危险因素。本项目将有利于理解PCP感染免疫的分子调控机制，为PCP患者的早期预警及治疗提供新的理论基础。

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