Department of Pathobiology, Cleveland Clinic, Cleveland, OH.
Hepatology. 2010 Apr;51(4):1420-9. doi: 10.1002/hep.23427.
Altered expression and activity of immunomodulatory cytokines plays a major role in the pathogenesis of alcoholic liver disease. Chronic ethanol feeding increases the sensitivity of Kupffer cells, the resident hepatic macrophage, to lipopolysaccharide (LPS), leading to increased tumor necrosis factor alpha (TNF-alpha) expression. This sensitization is normalized by treatment of primary cultures of Kupffer cells with adiponectin, an anti-inflammatory adipokine. Here we tested the hypothesis that adiponectin-mediated suppression of LPS signaling in Kupffer cells is mediated via an interleukin-10 (IL-10)/heme oxygenase-1 (HO-1) pathway after chronic ethanol feeding. Knockdown of IL-10 expression in primary cultures of Kupffer cells with small interfering RNA (siRNA) prevented the inhibitory effect of globular adiponectin (gAcrp) on LPS-stimulated TNF-alpha expression. gAcrp increased IL-10 mRNA and protein expression, as well as expression of the IL-10 inducible gene, HO-1; expression was higher in Kupffer cells from ethanol-fed rats compared with pair-fed controls. Although IL-10 receptor surface expression on Kupffer cells was not affected by ethanol feeding, IL-10-mediated phosphorylation of STAT3 and expression of HO-1 was higher in Kupffer cells after ethanol feeding. Inhibition of HO-1 activity, either by treatment with the HO-1 inhibitor zinc protoporphyrin or by siRNA knockdown of HO-1, prevented the inhibitory effect of gAcrp on LPS-stimulated TNF-alpha expression in Kupffer cells. LPS-stimulated TNF-alpha expression in liver was increased in mice after chronic ethanol exposure. When mice were treated with cobalt protoporphyrin to induce HO-1 expression, ethanol-induced sensitivity to LPS was ameliorated.
gAcrp prevents LPS-stimulated TNF-alpha expression in Kupffer cells through the activation of the IL-10/STAT3/HO-1 pathway. Kupffer cells from ethanol-fed rats are highly sensitive to the anti-inflammatory effects of gAcrp; this sensitivity is associated with both increased expression and sensitivity to IL-10.
免疫调节细胞因子的表达和活性改变在酒精性肝病的发病机制中起着重要作用。慢性乙醇喂养增加了库普弗细胞（驻留于肝脏的巨噬细胞）对脂多糖（LPS）的敏感性，导致肿瘤坏死因子-α（TNF-α）表达增加。这种致敏作用可通过脂联素（抗炎脂肪因子）治疗原代培养的库普弗细胞而得到正常化。在这里，我们检验了这样一个假设，即脂联素介导的库普弗细胞中 LPS 信号的抑制是通过慢性乙醇喂养后白细胞介素-10（IL-10）/血红素加氧酶-1（HO-1）途径介导的。用小干扰 RNA（siRNA）敲低原代培养的库普弗细胞中的 IL-10 表达，可防止球形脂联素（gAcrp）对 LPS 刺激的 TNF-α表达的抑制作用。gAcrp 增加了 IL-10 mRNA 和蛋白质的表达，以及 IL-10 诱导基因 HO-1 的表达；与配对喂养的对照组相比，乙醇喂养的大鼠的库普弗细胞中的表达更高。虽然乙醇喂养对库普弗细胞表面 IL-10 受体的表达没有影响，但在乙醇喂养后，IL-10 介导的 STAT3 磷酸化和 HO-1 的表达在库普弗细胞中更高。HO-1 活性的抑制，无论是通过 HO-1 抑制剂锌原卟啉处理还是通过 HO-1 siRNA 敲低，都可以防止 gAcrp 对 LPS 刺激的库普弗细胞中 TNF-α表达的抑制作用。慢性乙醇暴露后，小鼠肝脏中 LPS 刺激的 TNF-α表达增加。当用钴原卟啉诱导 HO-1 表达治疗小鼠时，乙醇诱导的 LPS 敏感性得到改善。
gAcrp 通过激活 IL-10/STAT3/HO-1 途径来防止 LPS 刺激的库普弗细胞中 TNF-α的表达。来自乙醇喂养大鼠的库普弗细胞对 gAcrp 的抗炎作用非常敏感；这种敏感性与 IL-10 的表达和敏感性增加都有关。
