Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, United States.
Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia.
Alcohol. 2022 Mar;99:35-48. doi: 10.1016/j.alcohol.2021.11.005. Epub 2021 Dec 17.
Alcohol consumption remains a leading cause of liver disease worldwide, resulting in a complex array of hepatic pathologies, including steatosis, steatohepatitis, and cirrhosis. Individuals who progress to a rarer form of alcohol-associated liver disease (ALD), alcohol-associated hepatitis (AH), require immediate life-saving intervention in the form of liver transplantation. Rapid onset of AH is poorly understood and the metabolic mechanisms contributing to the progression to liver failure remain undetermined. While multiple mechanisms have been identified that contribute to ALD, no cures exist and mortality from AH remains high. To identify novel pathways associated with AH, our group utilized proteomics to investigate AH-specific biomarkers in liver explant tissues. The goal of the present study was to determine changes in the proteome as well as epigenetic changes occurring in AH. Protein abundance and acetylomic analyses were performed utilizing nHPLC-MS/MS, revealing significant changes to proteins associated with metabolic and inflammatory fibrosis pathways. Here, we describe a novel hepatic and serum biomarker of AH, glycoprotein NMB (GPNMB). The anti-inflammatory protein GPNMB was significantly increased in AH explant liver and serum compared to healthy donors by 50-fold and 6.5-fold, respectively. Further, bioinformatics analyses identified an AH-dependent decrease in protein abundance across fatty acid degradation, biosynthesis of amino acids, and carbon metabolism. The greatest increases in protein abundance were observed in pathways for focal adhesion, lysosome, phagosome, and actin cytoskeleton. In contrast with the hyperacetylation observed in murine models of ALD, protein acetylation was decreased in AH compared to normal liver across fatty acid degradation, biosynthesis of amino acids, and carbon metabolism. Interestingly, immunoblot analysis found epigenetic marks were significantly increased in AH explants, including Histone H3K9 and H2BK5 acetylation. The increased acetylation of histones likely plays a role in the altered proteomic profile observed, including increases in GPNMB. Indeed, our results reveal that the AH proteome is dramatically impacted through unanticipated and unknown mechanisms. Understanding the origin and consequences of these changes will yield new mechanistic insight for ALD as well as identify novel hepatic and serum biomarkers, such as GPNMB.
饮酒仍然是全球范围内导致肝脏疾病的主要原因,导致一系列复杂的肝脏病理,包括脂肪变性、脂肪性肝炎和肝硬化。进展为更罕见的酒精性肝病(ALD)形式的个体,即酒精性肝炎(AH),需要立即进行以肝移植为形式的救命干预。AH 的快速发作机制尚不清楚,导致肝功能衰竭的代谢机制仍未确定。虽然已经确定了多个导致 ALD 的机制,但尚无治愈方法,AH 的死亡率仍然很高。为了确定与 AH 相关的新途径,我们的小组利用蛋白质组学研究了肝移植组织中 AH 特异性生物标志物。本研究的目的是确定 AH 中蛋白质组和表观遗传变化。利用 nHPLC-MS/MS 进行蛋白质丰度和乙酰化组分析,揭示了与代谢和炎症纤维化途径相关的蛋白质的显著变化。在这里,我们描述了一种新型的 AH 肝和血清生物标志物,即糖蛋白 NMB(GPNMB)。与健康供体相比,AH 肝组织和血清中 GPNMB 的抗炎蛋白含量分别增加了 50 倍和 6.5 倍。此外,生物信息学分析确定了在脂肪酸降解、氨基酸生物合成和碳代谢中,AH 依赖性的蛋白质丰度降低。蛋白质丰度增加最大的是焦点黏附、溶酶体、吞噬体和肌动蛋白细胞骨架途径。与在 ALD 小鼠模型中观察到的乙酰化过度相反,与正常肝脏相比,AH 中脂肪酸降解、氨基酸生物合成和碳代谢中的蛋白质乙酰化降低。有趣的是,免疫印迹分析发现 AH 外植体中的表观遗传标记显著增加,包括组蛋白 H3K9 和 H2BK5 乙酰化。组蛋白的乙酰化增加可能在观察到的蛋白质组谱变化中发挥作用,包括 GPNMB 的增加。事实上,我们的结果表明,AH 蛋白质组受到意想不到和未知机制的显著影响。了解这些变化的起源和后果将为 ALD 提供新的机制见解,并确定新型肝和血清生物标志物,如 GPNMB。