转录抑制因子HMBOX1调控巨噬细胞极化对LPS/D-GalN诱导急性肝损伤保护作用的机制研究

Acute liver injury (ALI) is a clinical syndrome characterized by sudden and severe impairment of liver function. HMBOX1, a new type of transcription repressors, has been isolated from human pancreatic cDNA library. In our previous work, hepatic-specific HMBOX1 knockout mice was generated with Cre/LoxP approach, and we found that hepatic HMBOX1 showed a significant protection in LPS/D-GalN-induced acute liver injury (ALI) by inhibiting the infiltration and activation of macrophage and maintaing the cellular homeostasis. However, the function of HMBOX1 in macrophages and its effect on ALI development are not clear. Recently, we found a decreased macrophagic HMBOX1 level in LPS/D-GalN-induced ALI. However, the mechanism was considerable ambiguity. Here, Cre/LoxP approach was adopted to generate macrophage-specific HMBOX1 knockout mice (HmMφ) , which will offer a good model to explore the function of HMBOX1 in macrophage. To identify the relationship between HMBOX1 and ALI, the sensitivity to ALI will be analysed with HmMφ and control mice, and the effect of HMBOX1 on macrophage polarization will be explored. Then, pcDNA3.1-HMBOX1 plasmid and HMBOX1-siRNA were used to identify the effect of macrophagic HMBOX1 on polarization regulation pathway, including M1-related TLR4/NFκB pathway and IFNγ/IRF5 pathway, M2-related p38/AKT-mTOR pathway. The regulation mechanism of HMBOX1 on target genes will be explored. These findings will provide much information for the biological function and mechanism of macrophagic HMBOX1 in ALI and a potential target for ALI therapy.

急性肝损伤（ALI）是指各种原因引起的肝细胞坏死和肝功能异常。HMBOX1是一种新型转录抑制因子。前期研究发现，肝细胞HMBOX1可经抑制巨噬细胞浸润及活化、促进肝细胞自噬，发挥肝脏保护作用，而作为ALI病变的核心效应细胞，巨噬细胞虽表达较高水平HMBOX1，可抑制LPS诱导的巨噬细胞M1极化，但巨噬细胞HMBOX1对ALI的影响机制还不明确。本课题利用巨噬细胞HMBOX1敲除小鼠，分析巨噬细胞HMBOX1与ALI的相关性；过表达/沉默HMBOX1并研究其对M1极化相关通路（TLR4/NFκB、IFNγ/IRF5）及M2极化相关通路（p38/AKT-mTOR调节自噬）的调节作用，研究HMBOX1对靶基因的作用方式，阐明巨噬细胞HMBOX1在ALI病变中的调控机制，为ALI的临床诊治提供新的靶点和理论依据。

急性肝损伤（ALI）是指各种原因引起的肝细胞坏死和肝功能异常。转录抑制因子HMBOX1对ALI具有保护作用，肝细胞中HMBOX1通过负调巨噬细胞的浸润与活化，缓解ALI过程中炎症反应，发挥肝脏保护作用。巨噬细胞是ALI病变的核心效应细胞，其内HMBOX1可抑制LPS诱导的巨噬细胞活化，但对ALI的影响机制还不明确。本课题基于此提出HMBOX1通过下调巨噬细胞M1极化、上调M2极化的调控方式，促使巨噬细胞极化平衡向M2偏移的假说。本研究通过构建巨噬细胞HMBOX1过表达/敲除的细胞模型与动物模型，探索HMBOX1对巨噬细胞极化平衡的调节作用及机制。研究通过组学分析及分子生物学研究方法，在细胞水平进行HMBOX1对巨噬细胞增殖、自噬、极化等生物学行为的调控作用研究，并在动物模型中明确HMBOX1通过调控巨噬细胞极化平衡缓解机体炎症而发挥肝脏保护作用并验证细胞研究作用机制，以充实转录抑制因子HMBOX1 在急性肝损伤中的作用机制，为临床 ALI 的诊疗提供新的靶点与思路。