Mitochondrial Dysfunction in the Transition from NASH to HCC

Crosstalk between Epigenetics and Metabolic Reprogramming in Metabolic Dysfunction-Associated Steatotic Liver Disease-Induced Hepatocellular Carcinoma: A New Sight

Epigenetic and metabolic reprogramming alterations are two important features of tumors, and their reversible, spatial, and temporal regulation is a distinctive hallmark of carcinogenesis. Epigenetics, which focuses on gene regulatory mechanisms beyond the DNA sequence, is a new entry point for tumor therapy. Moreover, metabolic reprogramming drives hepatocellular carcinoma (HCC) initiation and progression, highlighting the significance of metabolism in this disease. Exploring the inter-regulatory relationship between tumor metabolic reprogramming and epigenetic modification has become one of the hot directions in current tumor metabolism research. As viral etiologies have given way to metabolic dysfunction-associated steatotic liver disease (MASLD)-induced HCC, it is urgent that complex molecular pathways linking them and hepatocarcinogenesis be explored. However, how aberrant crosstalk between epigenetic modifications and metabolic reprogramming affects MASLD-induced HCC lacks comprehensive understanding. A better understanding of their linkages is necessary and urgent to improve HCC treatment strategies. For this reason, this review examines the interwoven landscape of molecular carcinogenesis in the context of MASLD-induced HCC, focusing on mechanisms regulating aberrant epigenetic alterations and metabolic reprogramming in the development of MASLD-induced HCC and interactions between them while also updating the current advances in metabolism and epigenetic modification-based therapeutic drugs in HCC.

Pharmacological SERCA activation limits diet-induced steatohepatitis and restores liver metabolic function in mice

Metabolic dysfunction-associated steatotic liver disease is the most common form of liver disease and poses significant health risks to patients who progress to metabolic dysfunction-associated steatohepatitis. Fatty acid overload alters endoplasmic reticulum (ER) calcium stores and induces mitochondrial oxidative stress in hepatocytes, leading to hepatocellular inflammation and apoptosis. Obese mice have impaired liver sarco/ER Ca2+-ATPase (SERCA) function, which normally maintains intracellular calcium homeostasis by transporting Ca2+ ions from the cytoplasm to the ER. We hypothesized that restoration of SERCA activity would improve diet-induced steatohepatitis in mice by limiting ER stress and mitochondrial dysfunction. WT and melanocortin-4 receptor KO (Mc4r-/-) mice were placed on either chow or Western diet (WD) for 8 weeks. Half of the WD-fed mice were administered CDN1163 to activate SERCA, which reduced liver fibrosis and inflammation. SERCA activation also restored glucose tolerance and insulin sensitivity, improved histological markers of metabolic dysfunction-associated steatohepatitis, increased expression of antioxidant enzymes, and decreased expression of oxidative stress and ER stress genes. CDN1163 decreased hepatic citric acid cycle flux and liver pyruvate cycling, enhanced expression of mitochondrial respiratory genes, and shifted hepatocellular [NADH]/[NAD+] and [NADPH]/[NADP+] ratios to a less oxidized state, which was associated with elevated PUFA content of liver lipids. In sum, the data demonstrate that pharmacological SERCA activation limits metabolic dysfunction-associated steatotic liver disease progression and prevents metabolic dysfunction induced by WD feeding in mice.

The Role of HSP90 and TRAP1 Targets on Treatment in Hepatocellular Carcinoma

Hepatocellular Carcinoma (HCC) is the predominant form of liver cancer and arises due to dysregulation of the cell cycle control machinery. Heat Shock Protein 90 (HSP90) and mitochondrial HSP90, also referred to as TRAP1 are important critical chaperone target receptors for early diagnosis and targeting HCC. Both HSP90 and TRAP1 expression was found to be higher in HCC patients. Hence, the importance of HSP90 and TRAP1 inhibitors mechanism and mitochondrial targeted delivery of those inhibitors function is widely studied. This review also focuses on importance of protein-protein interactions of HSP90 and TRAP1 targets and association of its interacting proteins in various pathways of HCC. To further elucidate the mechanism, systems biology approaches and computational biology approach studies are well explored in the association of inhibition of herbal plant molecules with HSP90 and its mitochondrial type in HCC.

Metabolomic Analysis of Human Cirrhosis and Hepatocellular Carcinoma: A Pilot Study

BACKGROUND

Molecular changes in HCC development are largely unknown. As the liver plays a fundamental role in the body's metabolism, metabolic changes are to be expected.

AIMS

We aimed to identify metabolomic changes in HCC in comparison to liver cirrhosis (LC) patients, which could potentially serve as novel biomarkers for HCC diagnosis and prognosis.

METHODS

Metabolite expression from 38 HCC from the SORAMIC trial and 32 LC patients were analyzed by mass spectrometry. Metabolites with significant differences between LC and HCC at baseline were analyzed regarding expression over follow-up. In addition, association with overall survival was tested using univariate Cox proportional-hazard analysis.

RESULTS

41 metabolites showed differential expression between LC and HCC patients. 14 metabolites demonstrated significant changes in HCC patients during follow-up. Campesterol, lysophosphatidylcholine, octadecenoic and octadecadienoic acid, and furoylglycine showed a differential expression in the local ablation vs. palliative care group. High expression of eight metabolites (octadecenoic acid, 2-hydroxybutyrate, myo-inositol, isocitrate, erythronic acid, creatinine, pseudouridine, and erythrol) were associated with poor overall survival. The association between poor OS and octadecenoic acid and creatinine remained statistically significant even after adjusting for tumor burden and LC severity.

CONCLUSION

Our findings give promising insides into the metabolic changes during HCC carcinogenesis and provide candidate biomarkers for future studies. Campesterol and furoylglycine in particular were identified as possible biomarkers for HCC progression. Moreover, eight metabolites were detected as predictors for poor overall survival.

Natural compounds proposed for the management of non-alcoholic fatty liver disease

Although non-alcoholic fatty liver disease (NAFLD) presents as an intricate condition characterized by a growing prevalence, the often-recommended lifestyle interventions mostly lack high-level evidence of efficacy and there are currently no effective drugs proposed for this indication. The present review delves into NAFLD pathology, its diverse underlying physiopathological mechanisms and the available in vitro, in vivo, and clinical evidence regarding the use of natural compounds for its management, through three pivotal targets (oxidative stress, cellular inflammation, and insulin resistance). The promising perspectives that natural compounds offer for NAFLD management underscore the need for additional clinical and lifestyle intervention trials. Encouraging further research will contribute to establishing more robust evidence and practical recommendations tailored to patients with varying NAFLD grades.

An adenosine derivative promotes mitochondrial supercomplexes reorganization and restoration of mitochondria structure and bioenergetics in a diethylnitrosamine-induced hepatocellular carcinoma model

Hepatocellular carcinoma (HCC) progression is associated with dysfunctional mitochondria and bioenergetics impairment. However, no data about the relationship between mitochondrial supercomplexes (hmwSC) formation and ATP production rates in HCC are available. Our group has developed an adenosine derivative, IFC-305, which improves mitochondrial function, and it has been proposed as a therapeutic candidate for HCC. We aimed to determine the role of IFC-305 on both mitochondrial structure and bioenergetics in a sequential cirrhosis-HCC model in rats. Our results showed that IFC-305 administration decreased the number and size of liver tumors, reduced the expression of tumoral markers, and reestablished the typical architecture of the hepatic parenchyma. The livers of treated rats showed a reduction of mitochondria number, recovery of the mtDNA/nDNA ratio, and mitochondrial length. Also, IFC-305 increased cardiolipin and phosphatidylcholine levels and promoted hmwSC reorganization with changes in the expression levels of hmwSC assembly-related genes. IFC-305 in HCC modified the expression of several genes encoding elements of electron transport chain complexes and increased the ATP levels by recovering the complex I, III, and V activity. We propose that IFC-305 restores the mitochondrial bioenergetics in HCC by normalizing the quantity, morphology, and function of mitochondria, possibly as part of its hepatic restorative effect.

Association between dairy-rich dietary pattern and metabolic dysfunction-associated steatotic liver disease: Findings from the Korean Genome and Epidemiology Study

BACKGROUNDS

Dietary components and the development of metabolic dysfunction-associated liver disease (MASLD) are closely linked, but large-scale studies on dietary patterns and MASLD are scarce, most previous studies having focused on individual nutrients or foods rather than overall dietary patterns. Therefore, we aimed to investigate the association between dietary patterns and MASLD in Koreans.

METHODS

A total of 6,052 participants from the Korean Genome and Epidemiology Study. Dietary intake was assessed using a validated Korean semiquantitative food frequency questionnaire comprising 106 food items. Principal component analysis was used to determine the major dietary patterns. Cox proportional hazard regression analysis was performed to assess the association between the incidence of MASLD and dietary patterns.

RESULTS

Four major dietary patterns, namely carnivore, plant-based, dairy-rich, and starch-rich diet patterns, were identified. The carnivore, plant-based, and starch-rich diet patterns showed no significant association with incident MASLD, while the dairy-rich diet pattern was associated with a lower risk of MASLD, also showing significantly lower cumulative incidence of MASLD in the higher adherence to dairy-rich diet pattern.

CONCLUSION

The dairy-rich diet pattern was significantly associated with a lower risk of MASLD in Koreans. Appropriate dietary guidance based on dietary patterns is crucial for preventing MASLD.

Suppressing MTERF3 inhibits proliferation of human hepatocellular carcinoma via ROS-mediated p38 MAPK activation

Mitochondrial transcription termination factor 3 (MTERF3) negatively regulates mitochondrial DNA transcription. However, its role in hepatocellular carcinoma (HCC) progression remains elusive. Here, we investigate the expression and function of MTERF3 in HCC. MTERF3 is overexpressed in HCC tumor tissues and higher expression of MTERF3 positively correlates with poor overall survival of HCC patients. Knockdown of MTERF3 induces mitochondrial dysfunction, S-G2/M cell cycle arrest and apoptosis, resulting in cell proliferation inhibition. In contrast, overexpression of MTERF3 promotes cell cycle progression and cell proliferation. Mechanistically, mitochondrial dysfunction induced by MTERF3 knockdown promotes ROS accumulation, activating p38 MAPK signaling pathway to suppress HCC cell proliferation. In conclusion, ROS accumulation induced by MTERF3 knockdown inhibits HCC cell proliferation via p38 MAPK signaling pathway suggesting a promising target in HCC patients.

Molecular and cellular mechanisms underlying the hepatoprotective role of ghrelin against NAFLD progression

The underlying mechanisms for the development and progression of nonalcoholic fatty liver disease (NAFLD) are complex and multifactorial. Within the last years, experimental and clinical evidences support the role of ghrelin in the development of NAFLD. Ghrelin is a gut hormone that plays a major role in the short-term regulation of appetite and long-term regulation of adiposity. The liver constitutes a target for ghrelin, where this gut-derived peptide triggers intracellular pathways regulating lipid metabolism, inflammation, and fibrosis. Interestingly, circulating ghrelin levels are altered in patients with metabolic diseases, such as obesity, type 2 diabetes, and metabolic syndrome, which, in turn, are well-known risk factors for the pathogenesis of NAFLD. This review summarizes the molecular and cellular mechanisms involved in the hepatoprotective action of ghrelin, including the reduction of hepatocyte lipotoxicity via autophagy and fatty acid β-oxidation, mitochondrial dysfunction, endoplasmic reticulum stress and programmed cell death, the reversibility of the proinflammatory phenotype in Kupffer cells, and the inactivation of hepatic stellate cells. Together, the metabolic and inflammatory pathways regulated by ghrelin in the liver support its potential as a therapeutic target to prevent NAFLD in patients with metabolic disorders.

Evaluation of the efficacy of mitochondrial fission inhibitor (Mdivi-1) using non-alcoholic steatohepatitis (NASH) liver organoids

Non-alcoholic steatohepatitis (NASH) is known to progress to cirrhosis and hepatocellular carcinoma in some patients. Although NASH is associated with abnormal mitochondrial function related to lipid metabolism, mechanisms for the development and effective treatments are still unclear. Therefore, new approaches to elucidate the pathophysiology are needed. In the previous study, we generated liver organoids from different stages of NASH model mice that could recapitulate the part of NASH pathology. In the present study, we investigated the relationship between mitochondrial function and NASH disease by comparing NASH liver organoids (NLO) and control liver organoids (CLO). Compared with CLO, mitochondrial and organoid morphology was abnormal in NLO, with increased expression of mitochondrial mitogen protein, DRP1, and mitochondria-derived reactive oxygen species (ROS) production. Treatment of NLO with a DPR1 inhibitor, Mdivi-1 resulted in the improvement of morphology and the decreased expression of fibrosis-related markers, Col1a1 and Acta2. In addition, treatment of NASH model mice with Mdivi-1 showed a decrease in fatty liver. Mdivi-1 treatment also prevented fibrosis and ROS production in the liver. These results indicate that NLO undergoes enhanced metabolism and abnormal mitochondrial morphology compared with CLO. It was also suggested that Mdivi-1 may be useful as a therapeutic agent to ameliorate NASH pathology.

Mitochondrial Dysfunction-Associated Mechanisms in the Development of Chronic Liver Diseases

The liver is a major metabolic organ that performs many essential biological functions such as detoxification and the synthesis of proteins and biochemicals necessary for digestion and growth. Any disruption in normal liver function can lead to the development of more severe liver disorders. Overall, about 3 million Americans have some type of liver disease and 5.5 million people have progressive liver disease or cirrhosis, in which scar tissue replaces the healthy liver tissue. An estimated 20% to 30% of adults have excess fat in their livers, a condition called steatosis. The most common etiologies for steatosis development are (1) high caloric intake that causes non-alcoholic fatty liver disease (NAFLD) and (2) excessive alcohol consumption, which results in alcohol-associated liver disease (ALD). NAFLD is now termed "metabolic-dysfunction-associated steatotic liver disease" (MASLD), which reflects its association with the metabolic syndrome and conditions including diabetes, high blood pressure, high cholesterol and obesity. ALD represents a spectrum of liver injury that ranges from hepatic steatosis to more advanced liver pathologies, including alcoholic hepatitis (AH), alcohol-associated cirrhosis (AC) and acute AH, presenting as acute-on-chronic liver failure. The predominant liver cells, hepatocytes, comprise more than 70% of the total liver mass in human adults and are the basic metabolic cells. Mitochondria are intracellular organelles that are the principal sources of energy in hepatocytes and play a major role in oxidative metabolism and sustaining liver cell energy needs. In addition to regulating cellular energy homeostasis, mitochondria perform other key physiologic and metabolic activities, including ion homeostasis, reactive oxygen species (ROS) generation, redox signaling and participation in cell injury/death. Here, we discuss the main mechanism of mitochondrial dysfunction in chronic liver disease and some treatment strategies available for targeting mitochondria.

Coagulation Dysfunctions in Non-Alcoholic Fatty Liver Disease-Oxidative Stress and Inflammation Relevance

Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases. Its incidence is progressively rising and it is possibly becoming a worldwide epidemic. NAFLD encompasses a spectrum of diseases accounting for the chronic accumulation of fat within the hepatocytes due to various causes, excluding excessive alcohol consumption. In this study, we aimed to focus on finding evidence regarding the implications of oxidative stress and inflammatory processes that form the multifaceted pathophysiological tableau in relation to thrombotic events that co-occur in NAFLD and associated chronic liver diseases. Recent evidence on the pathophysiology of NAFLD suggests that a complex pattern of multidirectional components, such as prooxidative, proinflammatory, and prothrombotic components, better explains the multiple factors that promote the mechanisms underlying the fatty acid excess and subsequent processes. As there is extensive evidence on the multi-component nature of NAFLD pathophysiology, further studies could address the complex interactions that underlie the development and progression of the disease. Therefore, this study aimed to describe possible pathophysiological mechanisms connecting the molecular impairments with the various clinical manifestations, focusing especially on the interactions among oxidative stress, inflammation, and coagulation dysfunctions. Thus, we described the possible bidirectional modulation among coagulation homeostasis, oxidative stress, and inflammation that occurs in the various stages of NAFLD.

Oxidative Stress in Liver Pathophysiology and Disease

The liver is an organ that is particularly exposed to reactive oxygen species (ROS), which not only arise during metabolic functions but also during the biotransformation of xenobiotics. The disruption of redox balance causes oxidative stress, which affects liver function, modulates inflammatory pathways and contributes to disease. Thus, oxidative stress is implicated in acute liver injury and in the pathogenesis of prevalent infectious or metabolic chronic liver diseases such as viral hepatitis B or C, alcoholic fatty liver disease, non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). Moreover, oxidative stress plays a crucial role in liver disease progression to liver fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Herein, we provide an overview on the effects of oxidative stress on liver pathophysiology and the mechanisms by which oxidative stress promotes liver disease.

Interleukin-22 promotes the proliferation and migration of hepatocellular carcinoma cells via the phosphoinositide 3-kinase (PI3K/AKT) signaling pathway

BACKGROUND

Interleukin-22 (IL-22) is a pro-inflammatory cytokine released during the immune response in chronic liver injury. Although IL-22 mediates tissue regeneration, its uncontrolled production may generate a carcinogenic environment resulting in hepatocellular carcinoma (HCC). This study aims to identify the effect of IL-22 on anti-apoptotic and metastatic genes and the molecular pathways responsible for IL-22-mediated hepatic carcinogenesis.

METHODS AND RESULTS

Three cancerous liver lines, HepG2, SNU-387, Huh7, and one normal liver line, THLE2, were treated with IL-22. RT-qPCR analysis was conducted to study the role of IL-22 in altering the expression levels of anti-apoptotic genes, MCL-1 and BCL-2, and metastatic genes, MMP-7 and MMP-9. A significant increase in expression levels of these genes was observed after IL-22 treatment. Furthermore, to explore the major pathways involved in IL-22-mediated upregulation of anti-apoptotic and metastatic genes, cells were treated with inhibitors of JAK/STAT and PI3K/AKT pathways along with IL-22. Resultantly, a significant decrease in expression levels of target genes was observed, indicating the involvement of JAK/STAT and PI3K/AKT signaling cascades in IL-22-mediated oncogenesis. Finally, Cell Scratch assay was performed to check the effect of IL-22 and inhibitors of JAK/STAT and PI3K/AKT on the metastatic potential of liver cells. While migration was observed in Huh7 and THLE2 cells treated with IL-22, no migration was observed in cells treated with IL-22 along with JAK/STAT and PI3K/AKT inhibitors. Results indicate that IL-22 encourages metastasis in HCC cells via the JAK/STAT and PI3K/AKT pathways.

CONCLUSION

Results showed that IL-22 upregulates anti-apoptotic and metastatic genes in HCC through JAK/STAT and PI3K/AKT signaling pathways.

Type 2 Diabetes Mellitus and Liver Disease: Across the Gut-Liver Axis from Fibrosis to Cancer

Type 2 diabetes mellitus is a widespread disease worldwide, and is one of the cornerstones of metabolic syndrome. The existence of a strong relationship between diabetes and the progression of liver fibrosis has been demonstrated by several studies, using invasive and noninvasive techniques. Patients with type 2 diabetes mellitus (T2DM) and nonalcoholic fatty liver disease (NAFLD) show faster progression of fibrosis than patients without diabetes. Many confounding factors make it difficult to determine the exact mechanisms involved. What we know so far is that both liver fibrosis and T2DM are expressions of metabolic dysfunction, and we recognize similar risk factors. Interestingly, both are promoted by metabolic endotoxemia, a low-grade inflammatory condition caused by increased endotoxin levels and linked to intestinal dysbiosis and increased intestinal permeability. There is broad evidence on the role of the gut microbiota in the progression of liver disease, through both metabolic and inflammatory mechanisms. Therefore, dysbiosis that is associated with diabetes can act as a modifier of the natural evolution of NAFLD. In addition to diet, hypoglycemic drugs play an important role in this scenario, and their benefit is also the result of effects exerted in the gut. Here, we provide an overview of the mechanisms that explain why diabetic patients show a more rapid progression of liver disease up to hepatocellular carcinoma (HCC), focusing especially on those involving the gut-liver axis.

Role of lncRNAs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is among the deadliest cancer in human malignancies. It is the most common and severe type of primary liver cancer. However, the molecular mechanisms underlying HCC pathogenesis remain poorly understood. Long non-coding RNAs (lncRNAs), a new kind of RNA and epigenetic factors, play a crucial role in tumorigenesis and the progression of HCC. LncRNAs are capable of promoting the autophagy, proliferation, and migration of tumor cells by targeting and modulating the expression of downstream genes in signaling pathways related to cancer; these transcripts modify the activity and expression of various tumor suppressors and oncogenes. LncRNAs could act as biomarkers for treatment approaches such as immunotherapy, chemotherapy, and surgery to effectively treat HCC patients. Improved knowledge regarding the aetiology of HCC may result from an advanced understanding of lncRNAs. Enhanced oxidative stress in the mitochondrial and Endoplasmic reticulum leads to the activation of unfolded protein response pathway that plays a crucial role in the pathophysiology of hepatocellular carcinoma. The mutual regulation between LncRNAs and Endoplasmic reticulum (ER) stress in cancer and simultaneous activation of the unfolded protein response (UPR) pathway determines the fate of tumor cells in HCC. Mitochondria-associated lncRNAs work as essential components of several gene regulatory networks; abnormal regulation of mitochondria-associated lncRNAs may lead to oncogenesis, which provides further insight into the understanding of tumorigenesis and therapeutic strategies.

The Effect of Bioactive Aliment Compounds and Micronutrients on Non-Alcoholic Fatty Liver Disease

In the current review, we focused on identifying aliment compounds and micronutrients, as well as addressed promising bioactive nutrients that may interfere with NAFLD advance and ultimately affect this disease progress. In this regard, we targeted: 1. Potential bioactive nutrients that may interfere with NAFLD, specifically dark chocolate, cocoa butter, and peanut butter which may be involved in decreasing cholesterol concentrations. 2. The role of sweeteners used in coffee and other frequent beverages; in this sense, stevia has proven to be adequate for improving carbohydrate metabolism, liver steatosis, and liver fibrosis. 3. Additional compounds were shown to exert a beneficial action on NAFLD, namely glutathione, soy lecithin, silymarin, Aquamin, and cannabinoids which were shown to lower the serum concentration of triglycerides. 4. The effects of micronutrients, especially vitamins, on NAFLD. Even if most studies demonstrate the beneficial role of vitamins in this pathology, there are exceptions. 5. We provide information regarding the modulation of the activity of some enzymes related to NAFLD and their effect on this disease. We conclude that NAFLD can be prevented or improved by different factors through their involvement in the signaling, genetic, and biochemical pathways that underlie NAFLD. Therefore, exposing this vast knowledge to the public is particularly important.

Advances in the Diagnosis and Treatment of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease that affects approximately one-quarter of the global adult population, posing a significant threat to human health with wide-ranging social and economic implications. The main characteristic of NAFLD is considered that the excessive fat is accumulated and deposited in hepatocytes without excess alcohol intake or some other pathological causes. NAFLD is a progressive disease, ranging from steatosis to non-alcoholic steatohepatitis (NASH), cirrhosis, hepatocellular carcinoma, liver transplantation, and death. Therefore, NAFLD will probably emerge as the leading cause of end-stage liver disease in the coming decades. Unlike other highly prevalent diseases, NAFLD has received little attention from the global public health community. Liver biopsy is currently considered the gold standard for the diagnosis and staging of NAFLD because of the absence of noninvasive and specific biomarkers. Due to the complex pathophysiological mechanisms of NAFLD and the heterogeneity of the disease phenotype, no specific pharmacological therapies have been approved for NAFLD at present, although several drugs are in advanced stages of development. This review summarizes the current evidence on the pathogenesis, diagnosis and treatment of NAFLD.

The Non-Invasive Assessment of Circulating D-Loop and mt-ccf Levels Opens an Intriguing Spyhole into Novel Approaches for the Tricky Diagnosis of NASH

Nonalcoholic fatty liver disease (NAFLD) is the commonest liver disease worldwide affecting both adults and children. Nowadays, no therapeutic strategies have been approved for NAFLD management, and hepatic biopsy remains the gold standard procedure for its diagnosis. NAFLD is a multifactorial disease whose pathogenesis is affected by environmental and genetic factors, and it covers a spectrum of conditions ranging from simple steatosis up to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Several studies underlined the urgent need to develop an NAFLD risk prediction model based on genetics, biochemical indicators, and metabolic disorders. The loss of mitochondrial dynamics represents a typical feature of progressive NAFLD. The imbalance of mitochondrial lifecycle together with the impairment of mitochondrial biomass and function trigger oxidative stress, which in turn damages mitochondrial DNA (mtDNA). We recently demonstrated that the main genetic predictors of NAFLD led to mitochondrial dysfunction. Moreover, emerging evidence shows that variations in the displacement loop (D-loop) region impair mtDNA replication, and they have been associated with advanced NAFLD. Finally, lower levels of mitophagy foster the overload of damaged mitochondria, resulting in the release of cell-free circulating mitochondrial DNA (mt-ccf) that exacerbates liver injury. Thus, in this review we summarized what is known about D-loop region alterations and mt-ccf content during NAFLD to propose them as novel non-invasive biomarkers.

Hyperphosphorylation of hepatic proteome characterizes nonalcoholic fatty liver disease in S-adenosylmethionine deficiency

Methionine adenosyltransferase 1a (MAT1A) is responsible for hepatic S-adenosyl-L-methionine (SAMe) biosynthesis. Mat1a ^-/- mice have hepatic SAMe depletion, develop nonalcoholic steatohepatitis (NASH) which is reversed with SAMe administration. We examined temporal alterations in the proteome/phosphoproteome in pre-disease and NASH Mat1a ^-/- mice, effects of SAMe administration, and compared to human nonalcoholic fatty liver disease (NAFLD). Mitochondrial and peroxisomal lipid metabolism proteins were altered in pre-disease mice and persisted in NASH Mat1a ^-/- mice, which exhibited more progressive alterations in cytoplasmic ribosomes, ER, and nuclear proteins. A common mechanism found in both pre-disease and NASH livers was a hyperphosphorylation signature consistent with casein kinase 2α (CK2α) and AKT1 activation, which was normalized by SAMe administration. This was mimicked in human NAFLD with a metabolomic signature (M-subtype) resembling Mat1a ^-/- mice. In conclusion, we have identified a common proteome/phosphoproteome signature between Mat1a ^-/- mice and human NAFLD M-subtype that may have pathophysiological and therapeutic implications.

Metabolomics and Lipidomics Screening Reveal Reprogrammed Signaling Pathways toward Cancer Development in Non-Alcoholic Steatohepatitis

With the rising incidence of hepatocellular carcinoma (HCC) from non-alcoholic steatohepatitis (NASH), identifying new metabolic readouts that function in metabolic pathway perpetuation is still a demand. The study aimed to compare the metabolic signature between NASH and NASH-HCC patients to explore novel reprogrammed metabolic pathways that might modulate cancer progression in NASH patients. NASH and NASH-HCC patients were recruited and screened for metabolomics, and isotope-labeled lipidomics were targeted and profiled using the EXION-LCTM system equipped with a Triple-TOFTM 5600+ system. Results demonstrated significantly (p ≤ 0.05) higher levels of triacylglycerol, AFP, AST, and cancer antigen 19-9 in NASH-HCC than in NASH patients, while prothrombin time, platelet count, and total leukocyte count were decreased significantly (p ≤ 0.05). Serum metabolic profiling showed a panel of twenty metabolites with 10% FDR and p ≤ 0.05 in both targeted and non-targeted analysis that could segregate NASH-HCC from NASH patients. Pathway analysis revealed that the metabolites are implicated in the down-regulation of necroptosis, amino acid metabolism, and regulation of lipid metabolism by PPAR-α, biogenic amine synthesis, fatty acid metabolism, and the mTOR signaling pathway. Cholesterol metabolism, DNA repair, methylation pathway, bile acid, and salts metabolism were significantly upregulated in NASH-HCC compared to the NASH group. Metabolite-protein interactions network analysis clarified a set of well-known protein encoding genes that play crucial roles in cancer, including PEMT, IL4I1, BAAT, TAT, CDKAL1, NNMT, PNP, NOS1, and AHCYL. Taken together, reliable metabolite fingerprints are presented and illustrated in a detailed map for the most predominant reprogrammed metabolic pathways that target HCC development from NASH.

Silica nanoparticles aggravated the metabolic associated fatty liver disease through disturbed amino acid and lipid metabolisms-mediated oxidative stress

The metabolic associated fatty liver disease (MAFLD) is a public health challenge, leading to a global increase in chronic liver disease. The respiratory exposure of silica nanoparticles (SiNPs) has revealed to induce hepatotoxicity. However, its role in the pathogenesis and progression of MAFLD was severely under-studied. In this context, the hepatic impacts of SiNPs were investigated in vivo and in vitro through using ApoE^-/- mice and free fatty acid (FFA)-treated L02 hepatocytes. Histopathological examinations and biochemical analysis showed SiNPs exposure via intratracheal instillation aggravated hepatic steatosis, lipid vacuolation, inflammatory infiltration and even collagen deposition in ApoE^-/- mice, companied with increased hepatic ALT, AST and LDH levels. The enhanced fatty acid synthesis and inhibited fatty acid β-oxidation and lipid efflux may account for the increased hepatic TC/TG by SiNPs. Consistently, SiNPs induced lipid deposition and elevated TC in FFA-treated L02 cells. Further, the activation of hepatic oxidative stress was detected in vivo and in vitro, as evidenced by ROS accumulation, elevated MDA, declined GSH/GSSG and down-regulated Nrf2 signaling. Endoplasmic reticulum (ER) stress was also triggered in response to SiNPs-induced lipid accumulation, as reflecting by the remarkable ER expansion and increased BIP expression. More importantly, an UPLC-MS-based metabolomics analysis revealed that SiNPs disturbed the hepatic metabolic profile in ApoE^-/- mice, prominently on amino acids and lipid metabolisms. In particular, the identified differential metabolites were strongly correlated to the activation of oxidative stress and ensuing hepatic TC/TG accumulation and liver injuries, contributing to the progression of liver diseases. Taken together, our study showed SiNPs promoted hepatic steatosis and liver damage, resulting in the aggravation of MAFLD progression. More importantly, the disturbed amino acids and lipid metabolisms-mediated oxidative stress was a key contributor to this phenomenon from a metabolic perspective.

The Role of Noninvasive 13C-Octanoate Breath Test in Assessing the Diagnosis of Nonalcoholic Steatohepatitis

BACKGROUND

The diagnosis of NASH needs a liver biopsy, an invasive procedure that is not frequently accepted by patients. The aim of our study was to evaluate the efficacy of the ¹³C-Octanoate breath test (OBT) as a non-invasive surrogate marker to differentiate patients with NASH from patients with simple steatosis (NAFL).

METHODS

We performed a prospective study on patients with histologically established non-alcoholic steatohepatitis and no other hepatic disease. Each patient underwent a testing protocol, which included a clinical exam, laboratory blood tests, standard abdominal ultrasound, and a ¹³C-Octanoate breath test.

RESULTS

The study group included: 82 patients with steatohepatitis, 64 patients with simple steatosis, and 21 healthy volunteers. The univariate and bivariate analysis identified that significant values were the percent dose recovery (PDR) at 15 min-r = 0.65 (AUROC = 0.902) and cumulative percent dose recovery (cPDR) at 120 min-r = 0.69 (AUROC = 0.899).

DISCUSSION

Our study showed that ¹³C-OBT had good efficacy for identifying patients with NASH from those with NAFL (steatosis alone) but not those with NAFL from healthy subjects. Considering all these pathogenic steps in NASH we considered that OBT could have the clinical utility to identify patients at risk for NASH, especially "fast progressors".

Hepatocyte Mitochondrial Dynamics and Bioenergetics in Obesity-Related Non-Alcoholic Fatty Liver Disease

PURPOSE OF THE REVIEW

Mitochondrial dysfunction has long been proposed to play a crucial role in the pathogenesis of a considerable number of disorders, such as neurodegeneration, cancer, cardiovascular, and metabolic disorders, including obesity-related insulin resistance and non-alcoholic fatty liver disease (NAFLD). Mitochondria are highly dynamic organelles that undergo functional and structural adaptations to meet the metabolic requirements of the cell. Alterations in nutrient availability or cellular energy needs can modify their formation through biogenesis and the opposite processes of fission and fusion, the fragmentation, and connection of mitochondrial network areas respectively. Herein, we review and discuss the current literature on the significance of mitochondrial adaptations in obesity and metabolic dysregulation, emphasizing on the role of hepatocyte mitochondrial flexibility in obesity and NAFLD.

RECENT FINDINGS

Accumulating evidence suggests the involvement of mitochondrial morphology and bioenergetics dysregulations to the emergence of NAFLD and its progress to non-alcoholic steatohepatitis (NASH). Most relevant data suggests that changes in liver mitochondrial dynamics and bioenergetics hold a key role in the pathogenesis of NAFLD. During obesity and NAFLD, oxidative stress occurs due to the excessive production of ROS, leading to mitochondrial dysfunction. As a result, mitochondria become incompetent and uncoupled from respiratory chain activities, further promoting hepatic fat accumulation, while leading to liver inflammation, insulin resistance, and disease's deterioration. Elucidation of the mechanisms leading to dysfunctional mitochondrial activity of the hepatocytes during NAFLD is of predominant importance for the development of novel therapeutic approaches towards the treatment of this metabolic disorder.

Identifying a Novel Endoplasmic Reticulum-Related Prognostic Model for Hepatocellular Carcinomas

From the standpoint of the ER (endoplasmic reticulum), we were interested in identifying hub genes that impact clinical prognosis for HCC (hepatocellular carcinoma) patients and developing an ER-related prognostic model. Using TCGA-LIHC (The Cancer Genome Atlas-Liver Hepatocellular Carcinoma) and GSE14520 datasets, we conducted a series of analyses, which included differential gene screening, clinical prognostic analysis, Lasso regression, nomogram prediction, tumour clustering, gene functional enrichment, and tumour infiltration of immune cells. Following our screening for ER-related genes ( $n=1975$ ), we conducted a Lasso regression model to obtain five hub genes, KPNA2, FMO3, SPP1, KIF2C, and LPCAT1, using TCGA-LIHC as a training set. According to risk scores, HCC samples within either the TCGG-LIHC or GSE14520 cohort were categorized into high- and low-risk groups. Compared to the high-risk group of HCC patients, patients in the low-risk group had a better prognosis of OS (overall survival) or RFS (relapse-free survival). For TCGA-LIHC training set, with the factors of risk score, stage, age, and sex, we plotted a nomogram for 1-, 3-, and 5-year survival predictions. Our model demonstrated better clinical validity in both TCGA-LIHC and GSE14520 cohorts. Additionally, events related to biological enzyme activity, biological metabolic processes, or the cell cycle were associated with the prognostic risk of ER. Furthermore, two HCC prognosis-associated tumour clusters were identified by ER hub gene-based consensus clustering. Our findings indicated a link between ER prognostic signature-related high/low risk and tumour infiltration levels of several immune cells, such as “macrophages M2/M0” and “regulatory T cells (Tregs).” Overall, we developed a novel ER-related clinical prognostic model for HCC patients.

NAFLD: Mechanisms, Treatments, and Biomarkers

Nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic-associated fatty liver disease (MAFLD), is one of the most common causes of liver diseases worldwide. NAFLD is growing in parallel with the obesity epidemic. No pharmacological treatment is available to treat NAFLD, specifically. The reason might be that NAFLD is a multi-factorial disease with an incomplete understanding of the mechanisms involved, an absence of accurate and inexpensive imaging tools, and lack of adequate non-invasive biomarkers. NAFLD consists of the accumulation of excess lipids in the liver, causing lipotoxicity that might progress to metabolic-associated steatohepatitis (NASH), liver fibrosis, and hepatocellular carcinoma. The mechanisms for the pathogenesis of NAFLD, current interventions in the management of the disease, and the role of sirtuins as potential targets for treatment are discussed here. In addition, the current diagnostic tools, and the role of non-coding RNAs as emerging diagnostic biomarkers are summarized. The availability of non-invasive biomarkers, and accurate and inexpensive non-invasive diagnosis tools are crucial in the detection of the early signs in the progression of NAFLD. This will expedite clinical trials and the validation of the emerging therapeutic treatments.

The miR-23-27-24 cluster: an emerging target in NAFLD pathogenesis

The incidence of non-alcoholic fatty liver disease (NAFLD) is increasing globally, being the most widespread form of chronic liver disease in the west. NAFLD includes a variety of disease states, the mildest being non-alcoholic fatty liver that gradually progresses to non-alcoholic steatohepatitis, fibrosis, cirrhosis, and eventually hepatocellular carcinoma. Small non-coding single-stranded microRNAs (miRNAs) regulate gene expression at the miRNA or translational level. Numerous miRNAs have been shown to promote NAFLD pathogenesis and progression through increasing lipid accumulation, oxidative stress, mitochondrial damage, and inflammation. The miR-23-27-24 clusters, composed of miR-23a-27a-24-2 and miR-23b-27b-24-1, have been implicated in various biological processes as well as many diseases. Herein, we review the current knowledge on miR-27, miR-24, and miR-23 in NAFLD pathogenesis and discuss their potential significance in NAFLD diagnosis and therapy.

Mitochondrial-Related Transcriptome Feature Correlates with Prognosis, Vascular Invasion, Tumor Microenvironment, and Treatment Response in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is the most common subtype of primary liver cancer, which was highly correlated with metabolic dysfunction. Nevertheless, the association between nuclear mitochondrial-related transcriptome and HCC remained unclear.

Materials and Methods

A total of 147 nuclear mitochondrial-related genes (NMRGs) were downloaded from the MITOMAP: A Human Mitochondrial Genome Database. The training dataset was downloaded from The Cancer Genome Atlas (TCGA), while validation datasets were retrieved from the International Cancer Genome Consortium (ICGC) and Gene Expression Omnibus (GEO). The univariate and multivariate, and least absolute shrinkage and selection operator (LASSO) Cox regression analyses were applied to construct a NMRG signature, and the value of area under receiver operating characteristic curve (AUC) was utilized to assess the signature and nomogram. Then, data from the Genomics of Drug Sensitivity in Cancer (GDSC) were used for the evaluation of chemotherapy response in HCC.

Results

Functional enrichment of differentially expressed genes (DEGs) between HCC and paired normal tissue samples demonstrated that mitochondrial dysfunction was significantly associated with HCC development. Survival analysis showed a total of 35 NMRGs were significantly correlated with overall survival (OS) of HCC, and the LASSO Cox regression analysis further identified a 25-NMRG signature and corresponding prognosis score based on their transcriptional profiling. HCC patients were divided into high- and low-risk groups according to the median prognosis score, and high-risk patients had significantly worse OS (median OS: 27.50 vs. 83.18 months, P < 0.0001). The AUC values for OS at 1, 3, and 5 years were 0.79, 0.77, and 0.77, respectively. The prognostic capacity of NMRG signature was verified in the GSE14520 dataset and ICGC-HCC cohort. Besides, the NMRG signature outperformed each NMRG and clinical features in prognosis prediction and could also differentiate whether patients presented with vascular invasions (VIs) or not. Subsequently, a prognostic nomogram (C-index: 0.753, 95% CI: 0.703~0.804) by the integration of age, tumor metastasis, and NMRG prognosis score was constructed with the AUC values for OS at 1, 3, and 5 years were 0.82, 0.81, and 0.82, respectively. Notably, significant enrichment of regulatory and follicular helper T cells in high-risk group indicated the potential treatment of immune checkpoint inhibitors for these patients. Interestingly, the NMRG signature could also identify the potential responders of sorafenib or transcatheter arterial chemoembolization (TACE) treatment. Additionally, HCC patients in high-risk group appeared to be more sensitive to cisplatin, vorinostat, and methotrexate, reversely, patients in low-risk group had significantly higher sensitivity to paclitaxel and bleomycin instead.

Conclusions

In summary, the development of NMRG signature provided a more comprehensive understanding of mitochondrial dysfunction in HCC, helped predict prognosis and tumor microenvironment, and provided potential targeted therapies for HCC patients with different NMRG prognosis scores.

Livogrit Prevents Methionine-Cystine Deficiency Induced Nonalcoholic Steatohepatitis by Modulation of Steatosis and Oxidative Stress in Human Hepatocyte-Derived Spheroid and in Primary Rat Hepatocytes

The prevalence of nonalcoholic steatohepatitis (NASH), characterized by fatty liver, oxidative injury, and inflammation, has considerably increased in the recent years. Due to the complexity of NASH pathogenesis, compounds which can target different mechanisms and stages of NASH development are required. A robust screening model with translational capability is also required to develop therapies targeting NASH. In this study, we used HepG2 spheroids and rat primary hepatocytes to evaluate the potency of Livogrit, a tri-herbal Ayurvedic prescription medicine, as a hepatoprotective agent. NASH was developed in the cells via methionine and cystine-deficient cell culture media. Livogrit at concentration of 30 µg/mL was able to prevent NASH development by decreasing lipid accumulation, ROS production, AST release, NFκB activation and increasing lipolysis, GSH (reduced glutathione), and mitochondrial membrane potential. This study suggests that Livogrit might reduce the lipotoxicity-mediated ROS generation and subsequent production of inflammatory mediators as evident from the increased gene expression of FXR, FGF21, CHOP, CXCL5, and their normalization due to Livogrit treatment. Taken together, Livogrit showed the potential as a multimodal therapeutic formulation capable of attenuating the development of NASH. Our study highlights the potential of Livogrit as a hepatoprotective agent with translational possibilities.

Mitochondria and the NLRP3 Inflammasome in Alcoholic and Nonalcoholic Steatohepatitis

Alcoholic (ASH) and nonalcoholic steatohepatitis (NASH) are advanced stages of fatty liver disease and two of the most prevalent forms of chronic liver disease. ASH and NASH are associated with significant risk of further progression to cirrhosis and hepatocellular carcinoma (HCC), the most common type of liver cancer, and a major cause of cancer-related mortality. Despite extensive research and progress in the last decades to elucidate the mechanisms of the development of ASH and NASH, the pathogenesis of both diseases is still poorly understood. Mitochondrial damage and activation of inflammasome complexes have a role in inducing and sustaining liver damage. Mitochondrial dysfunction produces inflammatory factors that activate the inflammasome complexes. NLRP3 inflammasome (nucleotide-binding oligomerization domain-like receptor protein 3) is a multiprotein complex that activates caspase 1 and the release of pro-inflammatory cytokines, including interleukin-1β (IL-1β) and interleukin-18 (IL-18), and contributes to inflammatory pyroptotic cell death. The present review, which is part of the issue "Mitochondria in Liver Pathobiology", provides an overview of the role of mitochondrial dysfunction and NLRP3 activation in ASH and NASH.

Oxidative Stress and Redox Signaling in the Pathophysiology of Liver Diseases

The increased production of derivatives of molecular oxygen and nitrogen in the form of reactive oxygen species (ROS) and reactive nitrogen species (RNS) lead to molecular damage called oxidative stress. Under normal physiological conditions, the ROS generation is tightly regulated in different cells and cellular compartments. Any disturbance in the balance between the cellular generation of ROS and antioxidant balance leads to oxidative stress. In this article, we discuss the sources of ROS (endogenous and exogenous) and antioxidant mechanisms. We also focus on the pathophysiological significance of oxidative stress in various cell types of the liver. Oxidative stress is implicated in the development and progression of various liver diseases. We narrate the master regulators of ROS-mediated signaling and their contribution to liver diseases. Nonalcoholic fatty liver diseases (NAFLD) are influenced by a "multiple parallel-hit model" in which oxidative stress plays a central role. We highlight the recent findings on the role of oxidative stress in the spectrum of NAFLD, including fibrosis and liver cancer. Finally, we provide a brief overview of oxidative stress biomarkers and their therapeutic applications in various liver-related disorders. Overall, the article sheds light on the significance of oxidative stress in the pathophysiology of the liver. © 2022 American Physiological Society. Compr Physiol 12:3167-3192, 2022.

Mitochondrial fission factor promotes cisplatin resistancein hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver tumor and one of the leading causes of cancer-related death worldwide. Chemotherapeutic agents/regimens such as cisplatin (DDP) are frequently used for advanced HCC treatment. However, drug resistance remains a major hindrance and the underline mechanisms are not fully understood. In this study, we investigated the expression pattern and function of mitochondrial fission factor (Mff) in cisplatin-resistant HCC. We found that Mff is highly expressed in cisplatin-resistant HCC tissues and cell lines. Knockdown of Mff suppresses cell proliferation and promotes cell apoptosis of HCC/DDP cells. In addition, knockdown of Mff sensitizes Huh-7/DDP cells to cisplatin treatment, inhibits cell proliferation, migration and invasion, and enhances cell apoptosis. Confocal imaging showed that knockdown of Mff inhibits the mitochondrial fission and downregulates the expression of GTPase dynamin-related protein 1 (Drp1) in cisplatin-resistant Huh-7/DDP cells. Moreover, xenograft tumor model revealed that knockdown of Mff sensitizes Huh-7/DDP xenograft tumor to cisplatin treatment . In summary, our findings suggest that Mff regulates mitochondrial Drp1 expression and promotes cisplatin resistance in HCC, which provides a potential therapeutic target for the treatment of resistant HCC.

HSD17B13 and other liver fat-modulating genes predict development of hepatocellular carcinoma among HCV-positive cirrhotics with and without viral clearance after DAA treatment

BACKGROUND

Genetic predisposition to accumulate liver fat (expressed by a polygenic risk score, GRS, based on the number of at-risk alleles of PNPLA3, TM6SF2, MBOAT7 and GCKR) may influence the probability of developing hepatocellular carcinoma (HCC) after hepatitis C treatment. Whether this holds true taking into account carriage of the HSD17B13:TA splice variant, also affecting lipogenesis, and achievement of viral clearance (SVR), is unknown.

METHODS

PNPLA3, TM6SF2, MBOAT7, GCKR and HSD17B13 variants were determined in a cohort of 328 cirrhotic patients free of HCC before starting treatment with direct acting antivirals (DAA).

RESULTS

SVR in the study cohort was 96%. At the end of follow-up, N = 21 patients had been diagnosed an HCC; none of the genes included in the GRS was individually associated with HCC development. However, in a Cox proportional hazards model, a GRS > 0.457 predicted HCC independently of sex, diabetes, albumin, INR and FIB4. The fit of the model improved adding treatment outcome and carriage of the HSD17B13:TA splice variant, with sex, GRS > 0.457, HSD17B13:TA splice variant and failure to achieve an SVR (hazard ratio = 6.75, 4.24, 0.24 and 7.7, respectively) being independent predictors of HCC.

CONCLUSION

Our findings confirm that genes modulating liver fat and lipogenesis are important risk factors for HCC development among cirrhotics C treated with DAA.

Role of nutritional ketosis in the improvement of metabolic parameters following bariatric surgery

BACKGROUND

Ketone bodies (KB) might act as potential metabolic modulators besides serving as energy substrates. Bariatric metabolic surgery (BMS) offers a unique opportunity to study nutritional ketosis, as acute postoperative caloric restriction leads to increased lipolysis and circulating free fatty acids.

AIM

To characterize the relationship between KB production, weight loss (WL) and metabolic changes following BMS.

METHODS

For this retrospective study we enrolled male and female subjects aged 18-65 years who underwent BMS at a single Institution. Data on demographics, anthropometrics, body composition, laboratory values and urinary KB were collected.

RESULTS

Thirty-nine patients had data available for analyses [74.4% women, mean age 46.5 ± 9.0 years, median body mass index 41.0 (38.5; 45.4) kg/m², fat mass 45.2% ± 6.2%, 23.1% had diabetes, 43.6% arterial hypertension and 74.4% liver steatosis]. At 46.0 ± 13.6 d post-surgery, subjects had lost 12.0% ± 3.6% of pre-operative weight. Sixty-nine percent developed ketonuria. Those with nutritional ketosis were significantly younger [42.9 (37.6; 50.7) years vs 51.9 (48.3; 59.9) years, P = 0.018], and had significantly lower fasting glucose [89.5 (82.5; 96.3) mg/dL vs 96.0 (91.0; 105.3) mg/dL, P = 0.025] and triglyceride levels [108.0 (84.5; 152.5) mg/dL vs 152.0 (124.0; 186.0) mg/dL, P = 0.045] vs those with ketosis. At 6 mo, percent WL was greater in those with postoperative ketosis (-27.5% ± 5.1% vs 23.8% ± 4.3%, P = 0.035). Urinary KBs correlated with percent WL at 6 and 12 mo. Other metabolic changes were similar.

CONCLUSION

Our data support the hypothesis that subjects with worse metabolic status have reduced ketogenic capacity and, thereby, exhibit a lower WL following BMS.

Molecular targets regulating endoplasmic reticulum-mitochondria crosstalk for NAFLD treatment

Non-alcoholic fatty liver disease (NAFLD) as the most common chronic liver disease poses a significant impact on public healthcare and economic risk worldwide. As a multifactorial disease, NAFLD is usually associated with many comorbidities such as obesity, insulin resistance, hypertension, hyperlipidemia, diabetes, and cardiovascular disease. Without effectively preventive intervention, the advanced stage of NAFLD, non-alcoholic steatohepatitis (NASH), can progress to cirrhosis and hepatocellular carcinoma (HCC). However, there is no approved therapeutic treatment. Excessive fat accumulation in the liver is the hallmark of NAFLD, which can lead to mitochondrial dysfunction and endoplasmic reticulum (ER) stress. Dysfunction of two organelles also induces the upregulation of reactive oxygen species (ROS), activation of the unfolded protein response (UPR), and disruption of calcium transport, which promote NAFLD progression. Herein, this review summarized the current understanding of the roles of mitochondrial dysfunction and ER stress in the pathogenesis of NAFLD. Specifically, this review focused on the key molecules associated with the ER-mitochondria communication and different treatment options by targeting ER stress and mitochondrial dysfunction to treat NAFLD or NASH. Clinical trials to evaluate the therapeutic efficacy of representative agents, such as natural products, metabolites, and modulators of stress, have been reviewed and analyzed. Overall, recent findings suggest that targeting ER stress and mitochondrial dysfunction holds a promise for NAFLD treatment.

Early-Life Exposure to Low-Dose Cadmium Accelerates Diethylnitrosamine and Diet-Induced Liver Cancer

Maternal exposure to cadmium causes obesity and metabolic changes in the offspring, including nonalcoholic fatty liver disease-like pathology. However, whether maternal cadmium exposure accelerates liver cancer in the offspring is unknown. This study investigated the impact of early-life exposure to cadmium on the incidence and potential mechanisms of hepatocellular carcinoma (HCC) in offspring subjected to postweaning HCC induction. HCC in C57BL/6J mice was induced by diethylnitrosamine (DEN) injection at weaning, followed by a long-term high-fat choline-deficient (HFCD) diet. Before weaning, liver cadmium levels were significantly higher in mice with early-life cadmium exposure than in those without cadmium exposure. However, by 26 and 29 weeks of age, hepatic cadmium fell to control levels, while a significant decrease was observed in copper and iron in the liver. Both male and female cadmium-exposed mice showed increased body weight compared to non-cadmium-treated mice. For females, early-life cadmium exposure also worsened insulin intolerance but did not significantly promote DEN/HFCD diet-induced liver tumors. In contrast, in male mice, early-life cadmium exposure enhanced liver cancer induction by DEN/HFCD with high incidence and larger liver tumors. The liver peritumor tissue of early-life cadmium-exposed mice exhibited greater inflammation and disruption of fatty acid metabolism, accompanied by higher malondialdehyde and lower esterified triglyceride levels compared to mice without cadmium exposure. These findings suggest that early-life exposure to low-dose cadmium accelerates liver cancer development induced by a DEN/HFCD in male mice, probably due to chronic lipotoxicity and inflammation caused by increased uptake but decreased consumption of fatty acids.

Cargo proteins in extracellular vesicles: potential for novel therapeutics in non-alcoholic steatohepatitis

BACKGROUND

Extracellular vesicles (EVs) are recognized as novel cell-free therapeutics. Non-alcoholic steatohepatitis (NASH) remains a critical health problem. Herein, we show that EVs from pan peroxisome proliferator-activated receptor agonist-primed induced mesenchymal stem cell (pan PPAR-iMSC-EVs) has unique cargo protein signatures, and demonstrate its therapeutic function in NASH.

RESULTS

A unique protein signatures were identified in pan PPAR-iMSC-EVs against those from non-stimulated iMSC-EVs. NASH mice receiving pan PPAR-iMSC-EVs showed reduced steatotic changes and ameliorated ER stress and mitochondiral oxidative stress induced by inflammation. Moreover, pan PPAR-iMSC-EVs promoted liver regeneration via inhibiting apoptosis and enhancing proliferation.

CONCLUSIONS

We conclude that our strategy for enriching unique cargo proteins in EVs may facilitate the development of novel therapeutic option for NASH.

A novel HSF1 activator ameliorates nonalcoholic steatohepatitis by stimulating mitochondrial adaptive oxidation

BACKGROUND AND PURPOSE

Nonalcoholic steatohepatitis (NASH) is the more severe form of metabolic associated fatty liver disease (MAFLD), and no pharmacologic treatment approved as yet. Identification of novel therapeutic targets and their agents are critical to overcome the current inadequacy of drug treatment for NASH.

EXPERIMENTAL APPROACH

The correlation between heat shock factor 1 (HSF1) levels and the development of NASH and the target genes of HSF1 in hepatocyte were revealed by chromatin-immunoprecipitation sequencing. The effects and mechanisms of SYSU-3d in alleviating NASH were examined in relevant cell models and mouse models (the Ob/Ob mice, high-fat and high-cholesterol diet, the methionine-choline deficient diet fed mice). The drug-like properties of SYSU-3d in vivo were evaluated.

KEY RESULTS

HSF1 is progressively reduced with mitochondrial dysfunction in NASH pathogenesis and activation of this transcription factor by its newly-identified activator SYSU-3d efficiently ameliorated all manifestations of NASH in mice. When activated, the phosphorylated HSF1 (Ser326) translocated to nucleus and bound to the promoter of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) to induce mitochondrial biogenesis, thus increasing mitochondrial adaptive oxidation and inhibiting oxidative stress. The deletion of HSF1 and PGC-1α or recovery of HSF1 in HSF1-deficiency cells revealed the HSF1/PGC-1α metabolic axis mainly responsible for the anti-NASH effects of SYSU-3d independent of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK).

CONCLUSION AND IMPLICATIONS

Activation of HSF1 is a practicable therapeutic approach for NASH treatment via the HSF1/PGC-1α/mitochondrial axis, and SYSU-3d would take into consideration as a potential candidate for the treatment of NASH.

Sex-Dependent Effects of Eicosapentaenoic Acid on Hepatic Steatosis in UCP1 Knockout Mice

Visceral obesity may be a driving factor in nonalcoholic fatty liver disease (NAFLD) development. Previous studies have shown that the omega-3 polyunsaturated fatty acid, eicosapentaenoic acid (EPA), ameliorates obesity in high-fat (HF) fed male, C57Bl/6 mice at thermoneutral conditions, independent of uncoupling protein 1 (UCP1). Our goals herein were to investigate sex-dependent mechanisms of EPA in the livers of wild type (WT) and UCP1 knockout (KO) male and female mice fed a HF diet (45% kcal fat; WT-HF, KO-HF) with or without supplementation of 36 g/kg EPA (WT-EPA, KO-EPA). KO significantly increased body weight in males, with no significant reductions with EPA in the WT or KO groups. In females, there were no significant differences in body weight among KO groups and no effects of EPA. In males, liver TGs were significantly higher in the KO-HF group and reduced with EPA, which was not observed in females. Accordingly, gene and protein markers of mitochondrial oxidation, peroxisomal biogenesis and oxidation, as well as metabolic futile cycles were sex-dependently impacted by KO and EPA supplementation. These findings suggest a genotypic difference in response to dietary EPA supplementation on the livers of male and female mice with diet-induced obesity and housed at thermoneutrality.

Impact of aging on primary liver cancer: epidemiology, pathogenesis and therapeutics

Aging involves progressive physiological and metabolic reprogramming to adapt to gradual deterioration of organs and functions. This includes mechanisms of defense against pre-malignant transformations. Thus, certain tumors are more prone to appear in elderly patients. This is the case of the two most frequent types of primary liver cancer, i.e., hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). Accordingly, aging hallmarks, such as genomic instability, telomere attrition, epigenetic alterations, altered proteostasis, mitochondrial dysfunction, cellular senescence, exhaustion of stem cell niches, impaired intracellular communication, and deregulated nutrient sensing can play an important role in liver carcinogenesis in the elders. In addition, increased liver fragility determines a worse response to risk factors, which more frequently affect the aged population. This, together with the difficulty to carry out an early detection of HCC and iCCA, accounts for the late diagnosis of these tumors, which usually occurs in patients with approximately 60 and 70 years, respectively. Furthermore, there has been a considerable controversy on what treatment should be used in the management of HCC and iCCA in elderly patients. The consensus reached by numerous studies that have investigated the feasibility and safety of different curative and palliative therapeutic approaches in elders with liver tumors is that advanced age itself is not a contraindication for specific treatments, although the frequent presence of comorbidities in these individuals should be taken into consideration for their management.

Dairy protein intake is inversely related to development of non-alcoholic fatty liver disease

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is closely related to metabolic dysfunction, including insulin resistance, obesity, and metabolic syndrome. Dairy protein, rich in casein and whey protein, could help to reduce metabolic diseases. Therefore, we investigated the relationship between dairy protein intake and incident NAFLD.

METHODS

We analyzed data for 5171 adults aged 40-69 years from the Korean Genome and Epidemiology Study.(KoGES) Participants were separated as men, women aged ≥50 years, and women aged <50 years and then divided into tertiles based on dairy protein intake. NAFLD was defined as NAFLD liver fat score >-0.640. Scores were calculated as 1.18 × metabolic syndrome (Yes: 1, No: 0) + 0.45 × diabetes mellitus (Yes: 2, No: 0) + 0.15 × serum insulin +0.04 × AST - 0.94 × (AST/ALT) - 2.89. Cox proportional hazards spline curves were drawn to visualize dose-response relationships between dairy protein intake and incident NAFLD. Multiple Cox hazard regression analysis was conducted to examine associations between dairy protein intake and incident NAFLD.

RESULTS

The Cox proportional hazards spline curves revealed a negative linear relationship between dairy protein intake and incident NAFLD. The cumulative incidence of NAFLD significantly decreased with increasing tertiles of dairy protein intake in men and women aged ≥50 years. After adjusting for confounding factors, the hazard ratios and 95% confidence intervals for NAFLD in the middle and highest tertiles, compared to the lowest tertile, were 0.80 (0.67-0.96) and 0.71 (0.57-0.88) in men, 0.89 (0.72-1.09) and 0.72 (0.56-0.92) in women aged ≥50 years, and 1.01 (0.80-1.27) and 0.91 (0.67-1.24) in women aged <50 years, respectively.

CONCLUSIONS

We found that higher dairy protein intake was significantly and inversely associated with the risk of incident NAFLD in men and women aged ≥50 years. Consumption of milk and other dairy products could help prevent the development of NAFLD.

Hepatocellular carcinoma (HCC): the most promising therapeutic targets in the preclinical arena based on tumor biology characteristics

INTRODUCTION

: Hepatocellular carcinoma (HCC) is a malignant liver tumor characterized by high molecular heterogeneity, which has hampered the development of effective targeted therapies severely. Recent experimental data have unraveled novel promising targets for HCC treatment.

AREAS COVERED

: Eligible articles were retrieved from PubMed and Web of Science databases up to July 2021. This review summarizes the established targeted therapies for advanced HCC, focusing on the strategies to overcome drug resistance and the search for combinational treatments. In addition, conventional biomarkers holding the promises for HCC treatments and novel therapeutic targets from the research field are discussed.

EXPERT OPINION

: HCC is a molecularly complex disease, with several and distinct pathways playing critical roles in different tumor subtypes. Experimental models recapitulating the features of each tumor subset would be highly beneficial to design novel and more effective therapies against this disease. Furthermore, a deeper understanding of combinatorial drug synergism and the role of the tumor microenvironment in HCC will lead to improved therapeutic outcomes.

Multidimensional Biomarker Analysis Including Mitochondrial Stress Indicators for Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is accompanied by a complex and multifactorial pathogenesis with sequential progressions from inflammation to fibrosis and then to cancer. This heterogeneity interferes with the development of precise diagnostic and prognostic strategies for NAFLD. The current approach for the diagnosis of simple steatosis, steatohepatitis, and cirrhosis mainly consists of ultrasonography, magnetic resonance imaging, elastography, and various serological analyses. However, individual dry and wet biomarkers have limitations demanding an integrative approach for the assessment of disease progression. Here, we review diagnostic strategies for simple steatosis, steatohepatitis and hepatic fibrosis, followed by potential biomarkers associated with fat accumulation and mitochondrial stress. For mitochondrial stress indicators, we focused on fibroblast growth factor 21 (FGF21), growth differentiation factor 15 (GDF15), angiopoietin-related growth factor and mitochondrial-derived peptides. Each biomarker may not strongly indicate the severity of steatosis or steatohepatitis. Instead, multidimensional analysis of different groups of biomarkers based on pathogenic mechanisms may provide decisive diagnostic/prognostic information to develop a therapeutic plan for patients with NAFLD. For this purpose, mitochondrial stress indicators, such as FGF21 or GDF15, could be an important component in the multiplexed and contextual interpretation of NAFLD. Further validation of the integrative evaluation of mitochondrial stress indicators combined with other biomarkers is needed in the diagnosis/prognosis of NAFLD.

Palmitoyl-CoA effect on cytochrome c release, a key process of apoptosis, from liver mitochondria of rat with sucrose diet-induced obesity

Cytochrome c (cyt-c) release from the mitochondria to the cytosol is a key process in the initiation of hepatocyte apoptosis involved in the progression of non-alcoholic fatty liver disease (NAFLD) to fibrosis, cirrhosis and hepatocellular carcinoma. Hepatocyte apoptosis may be related to lipotoxicity due to the accumulation of palmitic acid and palmitoyl-CoA (Pal-CoA). Therefore, the aim of this study is to examine whether Pal-CoA induces cyt-c release from liver mitochondria of sucrose-fed rat (SF). Pal-CoA-induced cyt-c release was sensitive to cyclosporine A indicating the involvement of the mitochondrial membrane permeability transition (mMPT). In addition, cyt-c release from SF mitochondria remains significantly lower than C mitochondria despite the increased rate of H2O2 generation in SF mitochondria. The decreased cyt-c release from SF may be also related to the increased proportion of the palmitic acid-enriched cardiolipin, due to the high availibilty of palmitic acid in SF liver. The enrichment of cardiolipin molecular species with palmitic acid makes cardiolipin more resistant to peroxidation, a mechanism involved in the dissociation of cyt-c from mitochondrial inner membrane. These results suggest that Pal-CoA may participate in the progression of NAFLD to more severe disease through mechanisms involving cyt-c release and mMPT, a key process of apoptosis.

A Diet High in Fat and Fructose Induces Early Hepatic Mitochondrial Aging

ABSTRACT

To investigate the effect of high fructose diet on ultrastructure and content of hepatic mitochondria, we randomized 6-8 weeks old male C57Bl6/J mice to ad lib chow or high-fat-high-fructose (HF2) diet for 32 weeks. HF2-fed mice gained more weight, had higher plasma alanine aminotransferase, and fasting glucose levels and increased hepatic triglyceride content at all time points compared to chow-fed mice. HF2-fed mice had lower mitochondrial to nuclear DNA ratio compared to chow-fed mice. HF2-fed mice had lower average mitochondrial surface area and the number of mitochondria compared to chow-fed mice. HF2-fed mice had higher expression of the hepatic endoplasmic reticulum stress marker Chop, compared to chow-fed mice. A diet high in fat and fructose leads to enhanced hepatic mitochondrial aging, depletion, and dysfunction, which may be important determinants of nonalcoholic steatohepatitis pathogenesis.

Dietary Macronutrient Composition Differentially Modulates the Remodeling of Mitochondrial Oxidative Metabolism during NAFLD

Diets rich in fats and carbohydrates aggravate non-alcoholic fatty liver disease (NAFLD), of which mitochondrial dysfunction is a central feature. It is not clear whether a high-carbohydrate driven ‘lipogenic’ diet differentially affects mitochondrial oxidative remodeling compared to a high-fat driven ‘oxidative’ environment. We hypothesized that the high-fat driven ‘oxidative’ environment will chronically sustain mitochondrial oxidative function, hastening metabolic dysfunction during NAFLD. Mice (C57BL/6NJ) were reared on a low-fat (LF; 10% fat calories), high-fat (HF; 60% fat calories), or high-fructose/high-fat (HFr/HF; 25% fat and 34.9% fructose calories) diet for 10 weeks. De novo lipogenesis was determined by measuring the incorporation of deuterium from D₂O into newly synthesized liver lipids using nuclear magnetic resonance (NMR) spectroscopy. Hepatic mitochondrial metabolism was profiled under fed and fasted states by the incubation of isolated mitochondria with [¹³C₃]pyruvate, targeted metabolomics of tricarboxylic acid (TCA) cycle intermediates, estimates of oxidative phosphorylation (OXPHOS), and hepatic gene and protein expression. De novo lipogenesis was higher in the HFr/HF mice compared to their HF counterparts. Contrary to our expectations, hepatic oxidative function after fasting was induced in the HFr/HF group. This differential induction of mitochondrial oxidative function by the high fructose-driven ‘lipogenic’ environment could influence the progressive severity of hepatic insulin resistance.

Metabolic Spectrum of Liver Failure in Type 2 Diabetes and Obesity: From NAFLD to NASH to HCC

Liver disease is the spectrum of liver damage ranging from simple steatosis called as nonalcoholic fatty liver disease (NAFLD) to hepatocellular carcinoma (HCC). Clinically, NAFLD and type 2 diabetes coexist. Type 2 diabetes contributes to biological processes driving the severity of NAFLD, the primary cause for development of chronic liver diseases. In the last 20 years, the rate of non-viral NAFLD/NASH-derived HCC has been increasing rapidly. As there are currently no suitable drugs for treatment of NAFLD and NASH, a class of thiazolidinediones (TZDs) drugs for the treatment of type 2 diabetes is sometimes used to improve liver failure despite the risk of side effects. Therefore, diagnosis, prevention, and treatment of the development and progression of NAFLD and NASH are important issues. In this review, we will discuss the pathogenesis of NAFLD/NASH and NAFLD/NASH-derived HCC and the current promising pharmacological therapies of NAFLD/NASH. Further, we will provide insights into "adipose-derived adipokines" and "liver-derived hepatokines" as diagnostic and therapeutic targets from NAFLD to HCC.

Mitochondrial dysfunction and mitochondrion-targeted therapeutics in liver diseases

The liver is a vital metabolic and detoxifying organ and suffers diverse endogenous or exogenous damage. Hepatocyte mitochondria experience various structural and functional defects from liver injury, bearing oxidative stress, metabolic dysregulation, and the disturbance of mitochondrial quality control (MQC) mechanisms. Mitochondrial malfunction initiates the mitochondria-mediated apoptotic pathways and the release of damage signals, aggravating liver damage and disease progression via inflammation and reparative fibrogenesis. Removal of mitochondrial impairment or the improvement of MQC mechanisms restore mitochondrial homeostasis and benefit liver health. This review discusses the association of mitochondrial disorders with hepatic pathophysiological processes and the resultant potential of mitochondrion-targeting therapeutics for hepatic disorders. The recent advances in the MQC mechanisms and the mitochondrial-derived damage-associated molecular patterns (DAMPs) in the pathology and treatment of liver disease are particularly focussed.