GPR81 & GPR109a Regulate Innate Immune Injury in Sterile Inflammation

肝脏或胰腺的急性损伤通过TOLL导致快速无菌炎症反应（SIR）- 类受体（TLR）刺激，特征为水肿、细胞浸润和进一步的实质细胞 死亡许多证据表明SIR在胰腺和肝脏损伤中起着至关重要的作用。 促进SIR分辨率的信号知之甚少。乳酸盐和β- 羟基丁酸在炎症部位产生，并通过特定细胞表面受体发出信号 分别为GPR 81和GPR 109 a。 我们的初步数据表明，在对乙酰氨基酚或LPS/半乳糖胺诱导的急性肝损伤中， 在caerulein诱导的急性胰腺炎中：i.补充乳酸或β-羟基丁酸 减少肝脏和胰腺中的炎症和组织损伤，并减少TLR驱动的促增殖反应， 体外巨噬细胞中的炎症反应，ii. GPR 81或GPR 109 a体内敲低显著 增强肝损伤，减少细胞保护剂hmox 1的诱导，并提高死亡率， LPS/半乳糖胺诱导的肝炎，iii. GPR 81和GPR 109 a的表达主要在 肝脏中的巨噬细胞区室，和iv.乳酸盐和β-羟基丁酸盐需要GPR 相互作用蛋白ARRB 2用于抑制巨噬细胞中TLR 4驱动的促炎反应。 已知ARRB 2信号传导抑制下游NF-B依赖性促炎信号传导 TLR受体。还已知GPR 109 a激动剂烟酸通过NFE 2诱导hmox 1 转录因子依赖途径。已知HMOX 1促进巨噬细胞的极化 免疫表型朝向M2交替活跃状态，远离M1经典亲- 炎症状态 我们假设GPR 81和GPR 109 a受体及其配体限制了先天性免疫介导的 通过β-抑制蛋白2（ARRB 2）途径和NFE 2依赖性血红素加氧酶1的炎症 （HMOX 1）途径。 目的1：鉴定ARRB 2和NFE 2信号通路对GPR 81和GPR 109 a介导的细胞凋亡的作用。 通过使用ARRB 2和NFE 2基因敲除小鼠来调节无菌炎症反应， 分离的巨噬细胞和急性胰腺炎和急性肝损伤的体内模型的研究。 目的2：确定GPR 81和GPR 109 a信号转导在诱导hmox 1和抑制hmox 1中的协同作用。 NF-B依赖性促炎反应在分离的巨噬细胞中对TLR 4和TLR 9配体， LPS治疗的体内和LPS/cereulein胰腺炎的体内。 这项工作将确定GPR 81和GPR 109 a的详细细胞和分子机制 介导的无菌炎症反应的调节。

Acute injury of the liver or pancreas results in a rapid sterile inflammatory response (SIR) through TOLL- like receptor (TLR) stimulation characterized by edema, cellular infiltrate, and further parenchymal cell death. Many lines of evidence point towards the SIR having a vital role in pancreatic and liver damage. The signals which promote resolution of the SIR are poorly understood. Lactate and beta- hydroxybutyrate are produced at sites of inflammation and signal through specific cell curface receptors GPR81 and GPR109a, respectively. Our preliminary data demonstrate that in acetaminophen or LPS/galactosamine induced acute liver injury and in caerulein-induced acute pancreatitis: i. supplementation with lactate or beta-hydroxybutyrate decreases inflammation and tissue injury in the liver and pancreas and decreases TLR driven pro- inflammatory responses in macrophages in vitro, ii. in vivo knockdown of GPR81 or GPR109a markedly enhances liver injury, reduces induction of the cytoprotectant hmox1, and promotes mortality in LPS/galactosamine induced hepatitis, iii. GPR81 and GPR109a expression is predominantly in the macrophage compartment in the liver, and iv. lactate and beta-hydroxybutyrate require the GPR interacting protein ARRB2 for suppression of TLR4 driven pro-inflammatory responses in macrophages. It is known that ARRB2 signaling suppresses NF-¿B dependent pro-inflammatory signaling downstream of TLR receptors. It is also known that the GPR109a agonist niacin induces hmox1 through an NFE2 transcription factor dependent pathway. HMOX1 is known to promote polarization of macrophage immune phenotype towards the M2 alternatively active state and away from the M1 classical pro- inflammatory state. We hypothesize that GPR81 and GPR109a receptors and their ligands limit innate immune mediated inflammation through beta-arrestin 2 (ARRB2) pathways and NFE2-dependent heme-oxygenase 1 (HMOX1) pathways. AIM 1: Identify the contribution of ARRB2 and NFE2 signaling to GPR81 and GPR109a mediated modulation of the sterile inflammatory response through use of knockout mice for arrb2 and nfe2 and study of isolated macrophages and in vivo models of acute pancreatitis and acute liver injury. AIM 2: Determine synergy between GPR81 and GPR109a signaling in inducing hmox1 and suppressing NF-¿B dependent pro-inflammatory responses to TLR4 and TLR9 ligands in isolated macrophages, in vivo with LPS treatment, and in vivo in LPS/cearulein pancreatitis. The proposed work will identify a detailed cellular and molecular mechanism for GPR81 and GPR109a mediated regulation of the sterile inflammatory response.