目的·探讨沉默信息调节因子2（silent information regulator 2，SIRT2）通过组蛋白H4第8位赖氨酸（H4K8）去乳酸化修饰对早期感染后巨噬细胞免疫表型的调节作用及相应机制。方法·使用佛波醇-12-肉豆蔻酸酯-13-乙酸酯（phorbol-12-myristate-13-acetate，PMA）诱导人单核细胞白血病THP-1细胞，使其分化为具有巨噬细胞特性的人血单核细胞株（PMA-primed THP-1，pTHP-1），再以脂多糖（lipopolysaccharide，LPS）刺激建立巨噬细胞感染模型。将未经LPS处理的巨噬细胞（pTHP-1）设为对照（CTRL）组，经过LPS处理的巨噬细胞设为感染（LPS）组。通过蛋白质印迹法（Western blotting）检测巨噬细胞中组蛋白乳酸化各位点修饰水平、组蛋白乙酰化各位点修饰水平及SIRT2蛋白水平；通过实时荧光定量PCR（RT-qPCR）方法检测2组间糖酵解限速酶乳酸脱氢酶A（lactate dehydrogenase A，LDHA）、肝脏磷酸果糖激酶（phosphofructokinase liver type，PKFL），糖酵解调剂因子低氧诱导因子1α（hypoxia inducible factor 1α，HIF-1α），以及Sirtuin家族基因和HDAC家族基因表达水平；通过Transwell方法检测巨噬细胞趋化能力；使用慢病毒包装及细胞感染方法建立SIRT2过表达细胞系；使用RNA测序技术（RNA sequencing，RNA-seq）与染色质免疫共沉淀测序技术（chromatin immunoprecipitation sequencing，ChIP-seq）交互分析方法对组蛋白H4第8位赖氨酸乳酸化（lactylation of histone H4 lysine 8，H4K8la）特异性结合的基因进行差异性分析及通路富集分析。结果·相较于CTRL组，LPS组巨噬细胞糖酵解上调，组蛋白H4K8位点乳酸化水平显著增加（P<0.05），而组蛋白其余位点乙酰化水平未见显著变化。所有已知的具有去乳酸化修饰功能的酶中，仅SIRT2在LPS处理后出现显著降低（P<0.05），且SIRT2过表达可显著抑制巨噬细胞中组蛋白H4K8位点的乳酸化水平（P<0.05），但不影响组蛋白H4K8位点的乙酰化水平（P>0.05）。ChIP-seq与RNA-seq交互分析发现，组蛋白H4K8位点乳酸化修饰可调控巨噬细胞趋化相关基因，并且巨噬细胞的趋化能力在SIRT2过表达、H4K8la修饰水平下调后显著下降（P<0.05）。结论·SIRT2可通过去修饰组蛋白H4K8位点乳酸化改变趋化相关靶基因表达，从而降低巨噬细胞趋化能力。靶向SIRT2及H4K8la修饰将有助于控制巨噬细胞介导的炎症反应。

Objective ·To explore the regulatory role of silent information regulator 2 (SIRT2) in modulating the immune phenotype of macrophages after infection by removing the lactylation at H4K8 site of histone and the corresponding mechanism. Methods ·Human THP-1 leukemia cells were induced by phorbol 12-myristate 13-acetate (PMA) and stimulated by lipopolysaccharide (LPS) to establish a macrophage infection model. Macrophages without LPS treatment (pTHP-1) were set as the control (CTRL) group, and macrophages with LPS treatment were set as the infected (LPS) group. Western blotting was used to detect the level of histone modification and SIRT2 protein in macrophages. RT-qPCR was used to detect the expression level of glycolytic key enzymes [phosphofructokinase liver type (PFKL), lactate dehydrogenase A (LDHA)] and modulators genes hypoxia inducible factor 1α (HIF-1α), and the expression level of Sirtuin genes and HDAC genes between the two groups. Transwell was used to detect the ability of macrophage chemotaxis. Lentivirus packaging and cell infection were used to construct SIRT2 overexpression cell line. The interaction analysis method of RNA sequencing (RNA-seq) and chromatin immunoprecipitation sequencing (ChIP-seq) was used to analyze the difference and pathway enrichment of the genes specifically bound to H4K8 lactylation (H4K8la). Results ·Compared to the CTRL group, macrophage glycolysis was upregulated and the level of H4K8la was significantly increased in the LPS group (P<0.05), while the level of lactylation in other sites remained unchanged. Among all known enzymes with deacetylation modification function, only SIRT2 showed a significant decrease after LPS treatment (P<0.05), and overexpression of SIRT2 could significantly inhibit the level of H4K8la modification, while the level of H4K8ac remained unchanged (P>0.05). The interactive analysis of ChIP-seq and RNA-seq revealed that chemotaxis-related genes were regulated by H4K8la, and macrophage chemotaxis ability significantly decreased after the overexpression of SIRT2 and downregulation of H4K8la (P<0.05). Conclusion ·SIRT2 can change the expression of target genes related to chemotaxis by removing H4K8la modification, thereby reducing the chemotaxis ability of macrophages. Targeting SIRT2 and H4K8la modification may help control inflammation mediated by macrophages.