Saha Banishree, Bala Shashi, Hosseini Nooshin, Kodys Karen, Szabo Gyongyi
University of Massachusetts Medical School, Worcester, Massachusetts, USA.
University of Massachusetts Medical School, Worcester, Massachusetts, USA
J Leukoc Biol. 2015 May;97(5):963-973. doi: 10.1189/jlb.4A1014-485R. Epub 2015 Mar 4.
Macrophages play an important role in inflammation and liver injury. In ALD, activated macrophages, including M1 (proinflammatory) and M2 (anti-inflammatory) macrophages, are present in the liver. As KLF4 has been described as a regulator of macrophage polarization, we investigated its role in ALD. Chronic alcohol feeding in C57Bl/6 mice led to increased expression of M1 (TNF-, MCP1, and IL-1) and M2 (Arg1, Mrc1, and IL-10) genes and the frequency of CD206CD163 M2 macrophages in the liver. KLF4 mRNA and protein levels were increased in the livers of EtFed compared with PF mice. In macrophages, in vivo and in vitro, EtOH increased KLF4 levels, transcriptional activity, and expression of M1 and M2 genes. KLF4 knockdown and overexpression experiments demonstrated alcohol-dependent and -independent functions of KLF4 in regulating M1 and M2 markers. KLF4 siRNA treatment, alone and in synergy with alcohol, increased the levels of M1 markers. In contrast, KLF4 overexpression increased the levels of M2 and decreased M1 markers, and this was enhanced further by alcohol. KLF4 was regulated by alcohol and its metabolites. KLF4 mRNA and activity were increased in the presence of 4-MP, an inhibitor of ADH, and CYP2E1. However, inhibition of acetaldehyde breakdown attenuated KLF4 induction and promoted M1 polarization. We conclude that KLF4 regulates M1 and M2 markers in ALD. EtOH promotes KLF4 and M2 phenotype, whereas acetaldehyde attenuates KLF4 and promotes M1 macrophage, which may explain the increased presence of M1 and M2 macrophage populations in ALD.
巨噬细胞在炎症和肝损伤中发挥着重要作用。在酒精性肝病（ALD）中，活化的巨噬细胞，包括M1（促炎）和M2（抗炎）巨噬细胞，存在于肝脏中。由于KLF4已被描述为巨噬细胞极化的调节因子，我们研究了其在ALD中的作用。C57Bl/6小鼠长期酒精喂养导致肝脏中M1（肿瘤坏死因子-α、单核细胞趋化蛋白-1和白细胞介素-1）和M2（精氨酸酶1、甘露糖受体C型1和白细胞介素-10）基因表达增加以及CD206⁺CD163⁺ M2巨噬细胞频率增加。与配对喂养（PF）小鼠相比，乙醇喂养（EtFed）小鼠肝脏中KLF4 mRNA和蛋白水平升高。在体内和体外巨噬细胞中，乙醇增加了KLF4水平、转录活性以及M1和M2基因的表达。KLF4敲低和过表达实验证明了KLF4在调节M1和M2标志物方面具有酒精依赖性和非依赖性功能。单独使用KLF4 siRNA处理以及与酒精协同处理均增加了M1标志物的水平。相反，KLF4过表达增加了M2标志物水平并降低了M1标志物水平，且酒精进一步增强了这种作用。KLF4受酒精及其代谢产物的调节。在乙醇脱氢酶（ADH）和细胞色素P450 2E1（CYP2E1）的抑制剂4-甲基吡唑（4-MP）存在的情况下，KLF4 mRNA和活性增加。然而，抑制乙醛分解减弱了KLF4的诱导并促进了M1极化。我们得出结论，KLF4在ALD中调节M1和M2标志物。乙醇促进KLF4和M2表型，而乙醛减弱KLF4并促进M1巨噬细胞，这可能解释了ALD中M1和M2巨噬细胞群体增加的现象。
