Sepsis is a severe syndrome caused by the imbalance of the host response to infection, accompanied by multiple organ damage, especially acute lung injury. SET Domain-Containing 2 (SETD2) is a methyltransferase catalyzing H3 lysine 36 trimethylation (H3K36me3) that regulates multiple biological processes. This study focused on explicating the action of SETD2 on macrophage function in sepsis and the precise mechanism involved. Enzyme-linked immunosorbent assay, real-time quantitative polymerase chain reaction (RT-qPCR), and Western blotting were used to determine expression. Luciferase reporter assay and chromatin immunoprecipitation assay were conducted to detect the binding of SETD2 or H3K36me3 with the hypoxia-inducible factor 1, alpha subunit (Hif1a) gene. A sepsis-induced acute lung injury model was constructed via cecal ligation and puncture (CLP). SETD2 was decreased in RAW 264.7 cells stimulated by lipopolysaccharide (LPS). Besides, SETD2 suppressed M1 macrophage polarization and glycolysis caused by LPS. HIF-1α was enhanced in RAW 264.7 cells stimulated by LPS and inversely related to SETD2 expression. In addition, SETD2-catalyzed H3K36me3 bound to the Hif1a gene to modulate HIF-1α expression. Furthermore, Hif1a silencing suppressed Setd2 silencing-induced M1 macrophage polarization and glycolysis in RAW 264.7 cells. Moreover, overexpression of Setd2 inhibited CLP-induced lung injury and M1 macrophage polarization in mice. SETD2 suppressed M1 macrophage polarization and glycolysis via regulating HIF-1α through catalyzing H3K36me3 in sepsis.

脓毒症是宿主对感染反应失衡引起的一种严重综合征，伴有多器官损害，尤其是急性肺损伤。SET Domain-Containing 2 (SETD2) 是一种催化 H3 赖氨酸 36 三甲基化 (H3K36me3) 的甲基转移酶，可调节多种生物过程。本研究重点阐明 SETD2 对脓毒症巨噬细胞功能的作用及其确切机制。使用酶联免疫吸附测定、实时定量聚合酶链反应（RT-qPCR）和蛋白质印迹来测定表达。采用荧光素酶报告基因实验和染色质免疫沉淀实验检测SETD2或H3K36me3与缺氧诱导因子1α亚基（Hif1a）基因的结合。通过盲肠结扎穿刺（CLP）构建脓毒症引起的急性肺损伤模型。脂多糖 (LPS) 刺激的 RAW 264.7 细胞中 SETD2 减少。此外，SETD2 抑制 LPS 引起的 M1 巨噬细胞极化和糖酵解。HIF-1α 在 LPS 刺激的 RAW 264.7 细胞中增强，并且与 SETD2 表达呈负相关。此外，SETD2 催化 H3K36me3 与Hif1a基因结合，调节 HIF-1α 表达。此外，Hif1a沉默抑制了Setd2沉默诱导的 RAW 264.7 细胞中 M1 巨噬细胞极化和糖酵解。此外，Setd2的过度表达可抑制 CLP 诱导的小鼠肺损伤和 M1 巨噬细胞极化。SETD2 在脓毒症中通过催化 H3K36me3 来调节 HIF-1α，从而抑制 M1 巨噬细胞极化和糖酵解。