Scavo Maria Principia, Negro Roberto, Arrè Valentina, Depalo Nicoletta, Carrieri Livianna, Rizzi Federica, Mastrogiacomo Rita, Serino Grazia, Notarnicola Maria, De Nunzio Valentina, Lippolis Tamara, Pesole Pasqua Letizia, Coletta Sergio, Armentano Raffaele, Curri Maria Lucia, Giannelli Gianluigi
Personalized Medicine Laboratory, National Institute of Gastroenterology "S. de Bellis", IRCCS Research Hospital, Via Turi 27, Castellana Grotte, 70013, Bari, Italy.
Institute for Chemical-Physical Processes (IPCF)-CNR SS Bari, Via Orabona 4, 70125, Bari, Italy.
Cell Death Dis. 2023 Sep 26;14(9):635. doi: 10.1038/s41419-023-06161-9.
Excessive toxic lipid accumulation in hepatocytes underlies the development of non-alcoholic fatty liver disease (NAFLD), phenotypically characterized by necrosis and steato-fibrosis, whose molecular mechanism is not yet fully understood. Patients with NAFLD display an imbalanced palmitic (PA) to oleic acid (OA) ratio. Moreover, increasing experimental evidence points out a relevant involvement of the exosomal content in disease progression. Aim of the study was to highlight the PA/OA imbalance within circulating exosomes, the subsequent intracellular alterations, and the impact on NALFD. Liver cells were challenged with exosomes isolated from both healthy subjects and NAFLD patients. The exosomal PA/OA ratio was artificially modified, and biological effects were evaluated. A NAFLD-derived exosomal PA/OA imbalance impacts liver cell cycle and cell viability. OA-modified NAFLD-derived exosomes restored cellular viability and proliferation, whereas the inclusion of PA into healthy subjects-derived exosomes negatively affected cell viability. Moreover, while OA reduced the phosphorylation and activation of the necroptosis marker, Receptor-interacting protein 1 (phospho-RIP-1), PA induced the opposite outcome, alongside increased levels of stress fibers, such as vimentin and fibronectin. Administration of NAFLD-derived exosomes led to increased expression of Elongase 6 (ELOVL6), Stearoyl-CoA desaturase 1 (SCD1), Tumor necrosis factor α (TNF-α), Mixed-lineage-kinase-domain-like-protein (MLKL) and RIP-1 in the hepatocytes, comparable to mRNA levels in the hepatocytes of NAFLD patients reported in the Gene Expression Omnibus (GEO) database. Genetic and pharmacological abrogation of ELOVL6 elicited a reduced expression of downstream molecules TNF-α, phospho-RIP-1, and phospho-MLKL upon administration of NAFLD-derived exosomes. Lastly, mice fed with high-fat diet exhibited higher phospho-RIP-1 than mice fed with control diet. Targeting the Elongase 6-RIP-1 signaling pathway offers a novel therapeutic approach for the treatment of the NALFD-induced exosomal PA/OA imbalance.
肝细胞中过量的毒性脂质积累是非酒精性脂肪性肝病（NAFLD）发展的基础，其表型特征为坏死和脂肪性肝纤维化，其分子机制尚未完全阐明。NAFLD患者表现出棕榈酸（PA）与油酸（OA）比例失衡。此外，越来越多的实验证据表明外泌体内容物与疾病进展密切相关。本研究的目的是突出循环外泌体内的PA/OA失衡、随后的细胞内改变以及对NAFLD的影响。用从健康受试者和NAFLD患者中分离的外泌体刺激肝细胞。对外泌体的PA/OA比例进行人工调节，并评估生物学效应。NAFLD来源的外泌体PA/OA失衡影响肝细胞周期和细胞活力。OA修饰的NAFLD来源的外泌体恢复了细胞活力和增殖，而将PA纳入健康受试者来源的外泌体则对细胞活力产生负面影响。此外，虽然OA降低了坏死性凋亡标志物受体相互作用蛋白1（磷酸化RIP-1）的磷酸化和激活，但PA诱导了相反的结果，同时增加了波形蛋白和纤连蛋白等应激纤维的水平。给予NAFLD来源的外泌体导致肝细胞中延长酶6（ELOVL6）、硬脂酰辅酶A去饱和酶1（SCD1）、肿瘤坏死因子α（TNF-α）、混合谱系激酶结构域样蛋白（MLKL）和RIP-1的表达增加，与基因表达综合数据库（GEO）中报道的NAFLD患者肝细胞中的mRNA水平相当。ELOVL6的基因和药理学消除导致在给予NAFLD来源的外泌体后下游分子TNF-α、磷酸化RIP-1和磷酸化MLKL的表达降低。最后，高脂饮食喂养的小鼠比对照饮食喂养的小鼠表现出更高的磷酸化RIP-1水平。靶向延长酶6-RIP-1信号通路为治疗NAFLD诱导的外泌体PA/OA失衡提供了一种新的治疗方法。
