基于ARG-1的免疫代谢异常在肾脏固有巨噬细胞调控急性肾损伤慢性转归中的作用和机制研究

Patients who survive acute kidney injury (AKI) have a greater risk for chronic kidney disease (CKD). The true nature of AKI progressing to CKD is complex and poorly understood. It is identified that macrophage (Mø) plays a critical role in ischemia reperfusion injury (I/R) incited AKI that leads to fibrosis and chronic renal disease CKD. However, renal Mø are heterogeneous due to their phenotype plasticity in complex renal microenvironments. Therapeutic interventions targeting on Mø microenvironment showed no potential to halt the progression of CKD. Therefore, it needs to be a much greater understanding of the therapeutic targets of renal Mø to restore normal renal structure and function. Our recent studies have demonstrated that the significant feature of the chronic phase after AKI is the predominantly infiltration of kidney-resident macrophage with intrinsic arginase 1 (ARG-1) -related metabolic abnormalities. Accordingly, we speculate that renal damaged microenvironment induces intrinsic macrophages to produce ARG-1 and consume arginine, leading to arginine starvation and dysfunction in adjacent cells, accelerating chronic inflammation and progressive fibrosis. In this study, we will use the inducible intrinsic macrophage ARG-1 knock-in / knock-down mice to induce AKI-CKD injury model, or administration of ARG-1 inhibtor or siRNA, to explore wheather targeting on ARG-1 related immune metabolic abnormalities in kidney-resident macrophages can stop the progression of CKD.

急性肾损伤向慢性化转归（AKI-CKD）发生率高、预后不良，被认为与巨噬细胞密切相关。然而，直接干预肾脏巨噬细胞微环境，并不能完全逆转AKI-CKD的进展，是目前亟待解决的科学问题。我们发现，AKI慢性期最显著的特征是持续肾脏固有巨噬细胞（kidney-resident macrophage）浸润，同时存在精氨酸酶1（ARG-1）相关的代谢异常，这种异常与AKI-CKD的进展密切相关。据此，我们推测肾脏损伤微环境诱导固有巨噬细胞产生ARG-1消耗精氨酸，导致邻近细胞如肾小管上皮细胞、周细胞和纤维细胞精氨酸饥饿、功能障碍，并激活肌成纤维细胞，肾脏损伤迁延不愈。本研究拟利用可诱导性固有巨噬细胞ARG-1敲入/敲出小鼠，诱导AKI-CKD损伤模型，结合ARG-1靶向干预，明确肾脏固有巨噬细胞基于ARG-1的免疫代谢异常对AKI向慢性化和纤维化转归的影响和机制，为逆转AKI-CKD提供新的治疗思路

急性肾损伤AKI目前已成为严重威胁人类健康的全球性疾病，并且增加随后发展为慢性肾脏病CKD的风险。巨噬细胞浸润被认为是AKI进展的重要驱动力。巨噬细胞具有异质性和可塑性，既往巨噬细胞分为经典激活的M1型巨噬细胞和替代激活的M2型巨噬细胞，并且在肾脏疾病中有不同的作用。近年来随着10x单细胞测序技术在疾病研究中的应用，更多的巨噬细胞亚群被发现，为更深入研究肾脏疾病中巨噬细胞的功能以及相应的靶向干预提供了全新的方向。ARG1，即精氨酸酶1，过去主要被作为M2巨噬细胞的标记之一，研究表明ARG1在 UUO 诱导的肾纤维化模型中表达明显增高，提示 ARG1 可能通过其在浸润的巨噬细胞中的表达而参与肾纤维化的发生和发展。本研究主要探讨ARG1的表达对巨噬细胞的影响和表达ARG1的巨噬细胞在AKI-CKD进展中的作用。.本研究证实人体疾病肾脏中ARG1+细胞数量增加，并且ARG1+巨噬细胞浸润贯穿了AKI-CKD的全过程，大部分起源于骨髓单核细胞。成功构建巨噬细胞ARG1特异性敲出鼠，证实敲低巨噬细胞ARG1减轻I/R诱导的急性肾损伤和I/R诱导的肾纤维化。肾脏10x单细胞测序结果揭示ARG1+巨噬细胞具有更强的促炎和促纤维化功能。证实ARG1过表达的巨噬细胞可激活成纤维细胞从而促进肾脏纤维化。研究证实表达ARG1的巨噬细胞具有促纤维化的潜能，探究了精氨酸酶抑制剂干预下抑制精氨酸代谢可以在一定程度上减轻急性期的肾损伤，减少ARG1+巨噬细胞的浸润，减轻肾纤维化。.本研究证实ARG1+巨噬细胞亚群在急性肾损伤慢性化过程中具备的促炎和促纤维化作用，ARG1可诱导巨噬细胞向促纤维化表型转变，针对巨噬细胞 ARG1活性或表达进行干预可起到保护损伤肾脏的作用，为临床上治疗肾脏疾病提供了新思路。

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