State Key Lab of Molecular Oncology & Immunology Department, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No 17 Panjiayuan South Lane, Chaoyang District, Beijing, 100021, People's Republic of China.
BMC Med. 2022 Sep 5;20(1):279. doi: 10.1186/s12916-022-02481-3.
Some occult hepatitis B virus (HBV) infections are resulted from PreS mutations that reduce secretion of envelope protein (HBsAg). We investigated the ceramide amounts and species in hepatocytes infected with PreS variants that were isolated from HBsAg-seronegative patients with hepatocellular carcinoma (HCC) and the ceramide effects on autochthonous HCC development in murine models.
HBV PreS/S regions from 35 HBsAg-seronegative HCC patients were sequenced. Hepatocyte cell lines and male C57BL/6J mouse livers were transfected with two PreS variant representatives. The ceramides with variated lengths of fatty acyl chains were quantified. Tumour development was examined in the HBV-transfected mice fed different diet types.
In HBsAg-seronegative HCC patients, nonneoplastic liver tissues harboured HBsAg and replication-competent HBV. The most frequently detected PreS/S variants carried mutations of altered amino acid properties in HBsAg compared with an isolate from one HBsAg-seronegative HCC patient. Hepatocyte infection with PreS variants caused HBsAg retention within the endoplasmic reticulum and generated more amounts of ceramides with C16:0 ceramide elevated the highest. Saturated fatty acids aggravated the PreS variant-infected hepatocytes to generate abnormal amounts and species of ceramides, which with HBV proteins synergistically activated NLRP3 inflammasome in liver inflammatory macrophages. Liver tumours were only detected in HBV-transfected mice fed high-fat diet, with higher tumour loads in the PreS variant-transfected, associated with abnormal ceramide generation.
HBV PreS mutations which altered amino acid properties of envelope proteins inhibited HBsAg secretion. Hepatocyte infection with PreS variants generated abnormal ceramides which with HBV proteins coactivated NLRP3 inflammasome in liver macrophages to promote autochthonous HCC development.
一些隐匿性乙型肝炎病毒 (HBV) 感染是由前 S 区突变引起的，这些突变降低了包膜蛋白 (HBsAg) 的分泌。我们研究了从 HBsAg 阴性肝细胞癌 (HCC) 患者中分离的前 S 变异体感染的肝细胞中的神经酰胺含量和种类，以及神经酰胺对小鼠模型中同源性 HCC 发展的影响。
对 35 例 HBsAg 阴性 HCC 患者的 HBV PreS/S 区进行测序。用两种前 S 变异体代表物转染肝细胞系和雄性 C57BL/6J 鼠肝。定量分析具有不同脂肪酸链长度的神经酰胺。用不同饮食类型喂养的 HBV 转染小鼠检查肿瘤的发展。
在 HBsAg 阴性 HCC 患者中，非肿瘤性肝组织中存在 HBsAg 和复制性 HBV。与来自一位 HBsAg 阴性 HCC 患者的分离株相比，最常检测到的 PreS/S 变异体在 HBsAg 中携带改变氨基酸性质的突变。前 S 变异体感染肝细胞导致 HBsAg 在粗面内质网中滞留，并产生更多的 C16:0 神经酰胺。饱和脂肪酸加重了前 S 变异体感染的肝细胞产生异常数量和种类的神经酰胺，这些神经酰胺与 HBV 蛋白协同激活肝脏炎症巨噬细胞中的 NLRP3 炎性小体。只有在高脂肪饮食喂养的 HBV 转染小鼠中才检测到肝肿瘤，在前 S 变异体转染的小鼠中，肿瘤负荷更高，与异常神经酰胺生成有关。
改变包膜蛋白氨基酸性质的 HBV PreS 突变抑制了 HBsAg 的分泌。前 S 变异体感染肝细胞产生异常神经酰胺，与 HBV 蛋白协同激活肝脏巨噬细胞中的 NLRP3 炎性小体，促进同源性 HCC 的发展。
