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Nonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease (NAFLD), characterized with hepatocellular steatosis, ballooning, lobular inflammation, fibrotic progression, and insulin resistance. NASH may progress to cirrhosis and hepatocellular carcinoma (HCC), which are the major indications for liver transplantation and the causes for mortality. Thus far, there are no approved pharmacotherapeutics for the treatment of NASH. Given the complexity of NASH pathogenesis at multifaceted aspects, such as lipotoxicity, inflammation, insulin resistance, mitochondrial dysfunction and fibrotic progression, pharmacotherapeutics under investigation target different key pathogenic pathways to gain either the resolution of steatohepatitis or regression of fibrosis, ideally both. Varieties of pharmacologic candidates have been tested in clinical trials and have generated some positive results. On the other hand, recent failure or termination of a few phase II and III trials is disappointing in this field. In face to growing challenges in pharmaceutical development, this review intends to summarize the latest data of new medications which have completed phase II or III trials, and discuss the rationale and preliminary results of several combinatory options. It is anticipated that with improved understanding of NASH pathogenesis and critical endpoints, efficient pharmacotherapeutics will be available for the treatment of NASH with an acceptable safety profile., (© 2022. The Author(s), under exclusive licence to Shanghai Institute of Materia Medica, Chinese Academy of Sciences and Chinese Pharmacological Society.)

Background and Aims: Treatment of non-alcoholic steatohepatitis (NASH) is challenging, because suppressing fibrotic progression has not been achieved consistently by drug candidates currently in clinical trials. The aim of this study was to investigate the molecular interplays underlying NASH-associated fibrosis in a mouse NASH model and human specimens., Methods: Mice were divided into 4 groups: Controls; NASH (high fat/Calorie diet plus high fructose and glucose in drinking water, HFCD-HF/G) for 16 weeks; HFCD-HF/G plus docosahexaenoic acid (DHA) for 16 or 8 weeks., Results: Along with NASH progression, fibrotic deposition was documented in HFCD-HF/G-fed mice. Liver succinate content was significantly increased along with decreased expression of succinate dehydrogenase-A (SDH-A) in these mice; whereas, GPR-91 receptor expression was much enhanced in histology compared to control mice, and co-localized histologically with hepatic stellate cells (HSCs). Succinate content was increased in fatty acid-overloaded primary hepatocytes with significant oxidant stress and lipotoxicity. Exposure to succinate led to up-regulation of GPR-91 receptor in primary and immortalized HSCs. In contrast, suppression of GPR-91 receptor expression abolished succinate stimulatory role in GPR-91 expression and extracellular matrix production in HSCs. All these changes were minimized or abrogated by DHA supplementation in vivo or in vitro. Moreover, GPR-91 receptor expression correlates with severity of fibrosis in human NASH biopsy specimens., Conclusion: Succinate accumulation in steatotoic hepatocytes may result in HSC activation through GPR-91 receptor signalling in NASH progression, and the cross-talk between hepatocytes and HSC through GPR-91 signalling is most likely to be the molecular basis of fibrogenesis in NASH., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Activation of inflammation is an important mechanism in the development of nonalcoholic steatohepatitis (NASH). This study aims to delineate how mitophagy affects NLRP3 inflammasome activation in hepatic lipotoxicity. Mice were fed a high fat/calorie diet (HFCD) for 24 weeks. Primary rat hepatocytes were treated with palmitic acid (PA) for various periods of time. Mitophagy was measured by protein levels of LC3II and P62. NLRP3, caspase-1, interleukin (IL)-18, and IL-1β at mRNA and protein levels were used as indicators of inflammasome activation. Along with steatotic progression in HFCD-fed mice, ratio of LC3II/β-actin was decreased concurrently with increased levels of liver P62, NLRP3, caspase-1, IL-1β, IL-18, and serum IL-1β levels in late-stage NASH. PA treatment resulted in mitochondrial oxidative stress and initiated mitophagy in primary hepatocytes. The addition of cyclosporine A did not change LC3II/Τοmm20 ratios; but P62 levels were increased after an extended duration of PA exposure, indicating a defect in autophagic activity. Along with impaired mitophagy, mRNA and protein levels of NLRP3, caspase-1, IL-18 and IL-1β were upregulated by PA treatment. Pretreatment with MCC950, N-acetyl cysteine or acetyl-L-carnitine reversed inflammasome activation and a pyroptotic cascade. Additionally, mitophagic flux was partially recovered as indicated by increases in LC3II/Tomm20 ratio, parkin, and PINK1 expression, and decreased P62 expression. The findings suggest that impaired mitophagy triggers hepatic NLRP3 inflammasome activation in a murine NASH model and primary hepatocytes. The new insights into inflammasome activation through mitophagy advance our understanding of how fatty acids elicit lipotoxicity through oxidant stress and autophagy in mitochondria.

Nonalcoholic steatohepatitis is considered as a precancerous condition. However, hepatic carcinogenesis from NASH is poorly understood. This study aims to investigate the activation of pluripotent genes (c-Myc, Oct-4, KLF-4, and Nanog) and morphogenic gene (Gli-1) in hepatic progenitor cells from patient specimens and in an animal model to determine the possibility of normal stem/progenitor cells becoming the origin of NASH-HCC. In this study, expression of pluripotent and morphogenic genes in human NASH-HCC tissues was significantly upregulated compared to adjacent non-tumor liver tissues. After feeding high-fat/calorie diet plus high fructose/glucose in drinking water (HFC diet plus HF/G) for up to 12 months, mice developed obesity, insulin resistance, and steatohepatitis with significant necroptotic inflammation and fibrotic progression, as well as occurrence of hyperplastic nodules with dysplasia; and this model represents pathohistologically as a transition from NASH to NASH-HCC in a pre-carcinomatous stage. High expression of pluripotent and morphogenic genes was immunohistochemically visualized in the dysplasia areas of mouse liver, where there were many OV-6-positive cells, indicating proliferation of HOCs in NASH with fibrotic progression. Moreover, oncogenic transcription factors (c-Myc, KLF-4, and Nanog) were co-localized in these hepatic progenitor cells. In conclusion, pluripotent and morphogenic genes may contribute to the reprogramming of hepatic progenitor cells in driving these cells to be the origin of NASH-HCC in a steatotic and inflamed microenvironment.

Nonalcoholic steatohepatitis-associated hepatocellular carcinoma (NASH-HCC) is a malignancy whose incidents are rapidly increasing. However, the mechanisms that drive development of HCC in a steatotic microenvironment remain unknown. Here we report that the obesity-associated protein JCAD is expressed at significantly higher levels in human NASH-HCC specimens compared with pericarcinoma specimens. High JCAD expression was verified in multiple hepatoma cell lines. Forced overexpression of JCAD in hepatoma cells promoted tumor growth and proliferation, whereas JCAD silencing yielded opposite effects. JCAD interacted with the kinase domain of the tumor suppressor kinase LATS2, a core component of the Hippo signaling pathway. JCAD overexpression inhibited the ability of LATS2 to phosphorylate YAP in this pathway, in turn upregulating CCND1 and GLI2 to promote hepatoma cell proliferation. JCAD was induced by fatty acid overload in hepatic cells and was highly expressed in a mouse model of NASH-precarcinoma lesions, where the ratio of phospho-YAP to YAP was decreased. In human NASH-HCC specimens, JCAD expression and YAP phosphorylation patterns paralleled with the mouse model. Our findings illuminate a new role for JCAD and its critical interplay in the Hippo signaling cascade during the transition of NASH to HCC, with potential implications for therapeutic development in this setting. Cancer Res; 77(19); 5287-300. ©2017 AACR ., (©2017 American Association for Cancer Research.)