Zheng Chaowen, Li Siyuan, Lyu Huanran, Chen Cheng, Mueller Johannes, Dropmann Anne, Hammad Seddik, Dooley Steven, He Songqing, Mueller Sebastian
Center for Alcohol Research, University of Heidelberg, Heidelberg, Germany.
Division of Hepatobiliary Surgery, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, People's Republic of China.
Hepat Med. 2024 Sep 3;16:65-77. doi: 10.2147/HMER.S469990. eCollection 2024.
Both hepatic iron accumulation and hemolysis have been identified as independent prognostic factor in alcohol-related liver disease (ALD); however, the mechanisms still remain poorly understood. We here demonstrate that hepatocytes are able to directly ingest aged and ethanol-primed red blood cells (RBCs), a process termed efferocytosis.
Efferocytosis of RBCs was directly studied in vitro and observed by live microscopy for real-time visualization. RBCs pretreated with either CuSO or ethanol following co-incubation with Huh7 cells and murine primary hepatocytes. and other targets were measured by q-PCR.
As shown by live microscopy, oxidized RBCs, but not intact RBCs, are rapidly ingested by both Huh7 cells and murine primary hepatocytes within 10 minutes. In some cases, more than 10 RBCs were seen within hepatocytes, surrounding the nucleus. RBC efferocytosis also rapidly induces , its upstream regulator Nuclear factor erythroid 2-related factor 2 ( and , indicating efficient heme degradation. Preliminary data further suggest that hepatocyte efferocytosis of oxidized RBCs is, at least in part, mediated by scavenging receptors such as . Of note, pretreatment of RBCs with ethanol but also heme and bilirubin also initiated efferocytosis. In a cohort of heavy human drinkers, a significant correlation of hepatic with the heme degradation pathway was observed.
We here demonstrate that hepatocytes can directly ingest and degrade oxidized RBCs through efferocytosis, a process that can be also triggered by ethanol, heme and bilirubin. Our findings are highly suggestive for a novel mechanism of hepatic iron overload in ALD patients.
肝铁蓄积和溶血均已被确定为酒精性肝病（ALD）的独立预后因素；然而，其机制仍知之甚少。我们在此证明，肝细胞能够直接摄取老化且经乙醇预处理的红细胞（RBC），这一过程称为胞葬作用。
在体外直接研究RBC的胞葬作用，并通过实时显微镜观察进行实时可视化。将RBC用硫酸铜或乙醇预处理后，与Huh7细胞和小鼠原代肝细胞共同孵育。通过q-PCR检测其他靶点。
如实时显微镜所示，氧化的RBC而非完整的RBC在10分钟内被Huh7细胞和小鼠原代肝细胞迅速摄取。在某些情况下，肝细胞内可见10多个围绕细胞核的RBC。RBC胞葬作用还迅速诱导其上游调节因子核因子红细胞2相关因子2（Nrf2）及其下游靶基因表达，表明血红素有效降解。初步数据进一步表明，氧化RBC的肝细胞胞葬作用至少部分由清道夫受体如CD163介导。值得注意的是，用乙醇预处理RBC以及血红素和胆红素也可引发胞葬作用。在一组重度饮酒者中，观察到肝脏血红素加氧酶-1（HO-1）与血红素降解途径之间存在显著相关性。
我们在此证明，肝细胞可通过胞葬作用直接摄取和降解氧化的RBC，这一过程也可由乙醇、血红素和胆红素触发。我们的发现强烈提示了ALD患者肝铁过载的一种新机制。
