坏死中性粒细胞DAMPs-IgG免疫复合物共同活化cDC1表面Clec9A-FcγR受体介导SLE组织损伤的机制研究

Secondary necrosis of neutrophils is one of key factors in the development of tissue damage, however, the molecular mechanism of tissue damage in SLE induced by which is not fully understood. Clec9A as a conventional type 1 dendritic cells (cDC1s)-restricted receptor specific for F-actin that is exposed by necrotic cells, mediates cDC1s phagocyte and presents necrosis-related antigens. Our previous work demnstrated that the numbers of Clec9A+ cDC1 were significantly elevated in skin, lung and kidney tissues of SLE patients and model mice than controls, suggesting that they may be key targets for tissue damage induced by necrotic neutrophils. This project is to be confirmed by study with SLE patients, model mice, and cells in vitro that the important role of Clec9A+ cDC1s in necrotic neutrophil-induced tissue damage of SLE. Then, we further explore the mechanism of co-stimulation of Clec9A-FcγR receptors on surface of cDC1 with DAMPs-IgG-IC, which was combinated with necrotic neutrophil and autoantibody, promotes cross-presentation of necrosis-related antigens and releases of inflammatory cytokines. This study will provide theoretical and scientific basis for the intervention of adaptive immune response activated by necrotic neutrophils as a key target of SLE treatment.

中性粒细胞继发性坏死是介导组织损伤的关键因素之一，但其诱导SLE组织损伤的分子机制尚不十分清晰。1型经典树突状细胞（cDC1s）表面Clec9A特异性识别坏死细胞表面暴露的F-actin，内吞并提呈坏死细胞相关抗原。我们前期研究发现与对照组相比，SLE患者或模型小鼠皮肤、肺、肾脏组织中Clec9A+cDC1s数量显著升高，推测其可能是介导坏死中性粒细胞诱导组织损伤的关键靶点。本项目拟以SLE患者、小鼠模型及体外细胞实验证实cDC1s在坏死中性粒细胞诱导的SLE组织损伤中发挥的关键作用，并进一步探索坏死中性粒细胞释放DAMPs与自身抗体结合形成DAMPs-IgG-IC，共同活化cDC1s表面Clec9A-FcγR受体，促进坏死相关抗原交叉提呈及炎性细胞因子释放的分子机制。本研究将为干预坏死中性粒细胞激活的获得性免疫反应，作为SLE治疗的关键靶标提供理论基础及科学依据。

中性粒细胞继发性坏死是诱导组织损伤的关键因素之一，但其诱导SLE组织损伤的机制尚不十分清楚。1型经典树突状细胞（cDC1）表面Clec9A特异性识别坏死细胞暴露的F-actin，内吞并提呈坏死细胞相关抗原。本研究发现坏死中性粒细胞释放DAMPs如PR3、S100A8/A9、F-actin与SLE患者SLEDAI呈显著正相关；cDC1细胞比例及其表面Clec9A表达在SLE患者外周血和皮肤组织中均显著高于健康受试者。同时，CD8+T淋巴细胞活化释放的IFNγ和GranzymeB在SLE机体中均显著升高且与SLEDAI呈显著正相关，证明坏死中性粒细胞及Clec9A介导的抗原交叉提呈在SLE发病过程中发挥着重要的作用。我们进一步利用WT和Clec9a-/-小鼠建立SLE模型发现，Clec9A基因敲除降低SLE模型小鼠急性炎症反应：减少腹腔中性粒细胞、单核细胞的浸润以及炎性细胞因子的释放。注射Pristane28周后，Clec9a-/-SLE模型小鼠肺部及脾脏组织慢性损伤得到缓解，为利用Clec9A作为SLE治疗的潜在靶点提供理论依据。另外，本研究进一步证实坏死中性粒细胞及Clec9A介导CD8+T淋巴细胞活化在COVID-19疾病进展中发挥着重要的作用；并明确肺泡灌洗液IL-6、癌胚抗原CEA、IL-8、S100A8/A9和PR3可作为预测COVID-19重症肺炎的潜在指标。