Comprehensive molecular mechanisms and clinical therapy in nonalcoholic steatohepatitis: An overview and current perspectives

Steatotic Liver Disease: Pathophysiology and Emerging Pharmacotherapies

Steatotic liver disease (SLD) displays a dynamic and complex disease phenotype. Consequently, the metabolic dysfunction-associated steatotic liver disease (MASLD)/metabolic dysfunction-associated steatohepatitis (MASH) therapeutic pipeline is expanding rapidly and in multiple directions. In parallel, noninvasive tools for diagnosing and monitoring responses to therapeutic interventions are being studied, and clinically feasible findings are being explored as primary outcomes in interventional trials. The realization that distinct subgroups exist under the umbrella of SLD should guide more precise and personalized treatment recommendations and facilitate advancements in pharmacotherapeutics. This review summarizes recent updates of pathophysiology-based nomenclature and outlines both effective pharmacotherapeutics and those in the pipeline for MASLD/MASH, detailing their mode of action and the current status of phase 2 and 3 clinical trials. Of the extensive arsenal of pharmacotherapeutics in the MASLD/MASH pipeline, several have been rejected, whereas other, mainly monotherapy options, have shown only marginal benefits and are now being tested as part of combination therapies, yet others are still in development as monotherapies. Although the Food and Drug Administration (FDA) has recently approved resmetirom, additional therapeutic approaches in development will ideally target MASH and fibrosis while improving cardiometabolic risk factors. Due to the urgent need for the development of novel therapeutic strategies and the potential availability of safety and tolerability data, repurposing existing and approved drugs is an appealing option. Finally, it is essential to highlight that SLD and, by extension, MASLD should be recognized and approached as a systemic disease affecting multiple organs, with the vigorous implementation of interdisciplinary and coordinated action plans. SIGNIFICANCE STATEMENT: Steatotic liver disease (SLD), including metabolic dysfunction-associated steatotic liver disease and metabolic dysfunction-associated steatohepatitis, is the most prevalent chronic liver condition, affecting more than one-fourth of the global population. This review aims to provide the most recent information regarding SLD pathophysiology, diagnosis, and management according to the latest advancements in the guidelines and clinical trials. Collectively, it is hoped that the information provided furthers the understanding of the current state of SLD with direct clinical implications and stimulates research initiatives.

Perturbed liver gene zonation in a mouse model of non-alcoholic steatohepatitis

Liver zonation characterizes the separation of metabolic pathways along the lobules and is required for optimal hepatic function. Wnt signaling is a master regulator of spatial liver zonation. A perivenous-periportal Wnt activity gradient orchestrates metabolic zonation by activating gene expression in perivenous hepatocytes, while suppressing gene expression in their periportal counterparts. However, the understanding as to the liver gene zonation and zonation regulators in diseases is limited. Non-alcoholic steatohepatitis (NASH) is a chronic liver disease characterized by fat accumulation, inflammation, and fibrosis. Here, we investigated the perturbation of liver gene zonation in a mouse NASH model by combining spatial transcriptomics, bulk RNAseq and in situ hybridization. Wnt-target genes represented a major subset of genes showing altered spatial expression in the NASH liver. The altered Wnt-target gene expression levels and zonation spatial patterns were in line with the up regulation of Wnt regulators and the augmentation of Wnt signaling. Particularly, we found that the Wnt activator Rspo3 expression was restricted to the perivenous zone in control liver but expanded to the periportal zone in NASH liver. AAV8-mediated RSPO3 overexpression in controls resulted in zonation changes, and further amplified the disturbed zonation of Wnt-target genes in NASH, similarly Rspo3 knockdown in Rspo3+/- mice resulted in zonation changes of Wnt-target genes in both chow and HFD mouse. Interestingly, there were no impacts on steatosis, inflammation, or fibrosis NASH pathology from RSPO3 overexpression nor Rspo3 knockdown. In summary, our study demonstrated the alteration of Wnt signaling in a mouse NASH model, leading to perturbed liver zonation.

Diosgenin as a substitute for cholesterol alleviates NAFLD by affecting CYP7A1 and NPC1L1-related pathway

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) rapidly becomes the leading cause of end-stage liver disease or liver transplantation. Nowadays, there has no approved drug for NAFLD treatment. Diosgenin as the structural analogue of cholesterol attenuates hypercholesterolemia by inhibiting cholesterol metabolism, which is an important pathogenesis in NAFLD progression. However, there has been no few report concerning its effects on NAFLD so far.

METHODS

Using a high-fat diet & 10% fructose-feeding mice, we evaluated the anti-NAFLD effects of diosgenin. Transcriptome sequencing, LC/MS analysis, molecular docking simulation, molecular dynamics simulations and Luci fluorescent reporter gene analysis were used to evaluate pathways related to cholesterol metabolism.

RESULTS

Diosgenin treatment ameliorated hepatic dysfunction and inhibited NAFLD formation including lipid accumulation, inflammation aggregation and fibrosis formation through regulating cholesterol metabolism. For the first time, diosgenin was structurally similar to cholesterol, down-regulated expression of CYP7A1 and regulated cholesterol metabolism in the liver (p < 0.01) and further affecting bile acids like CDCA, CA and TCA in the liver and feces. Besides, diosgenin decreased expression of NPC1L1 and suppressed cholesterol transport (p < 0.05). Molecular docking and molecular dynamics further proved that diosgenin was more strongly bound to CYP7A1. Luci fluorescent reporter gene analysis revealed that diosgenin concentration-dependently inhibited the enzymes activity of CYP7A1.

CONCLUSION

Our findings demonstrated that diosgenin was identified as a specific regulator of cholesterol metabolism, which pave way for the design of novel clinical therapeutic strategies.

Ubiquitination of cytoplasmic HMGB1 by RNF186 regulates hepatic lipophagy in non-alcoholic fatty liver disease

BACKGROUND

Lipophagy is a vital biological process that maintains the balance of intracellular lipid metabolism in nonalcoholic fatty liver disease (NAFLD). However, the precise regulatory mechanism of RNF186 in hepatic lipophagy is still unclear. This study investigates the roles and mechanisms of RNF186 in the regulation of lipophagy during the development of NAFLD.

METHODS

In this study, we employed RNF186 knockout mice as well as human liver cells and mouse primary hepatocytes (MPHs) to investigate the role and mechanisms of RNF186 in lipophagy during the progression of NAFLD. Additionally, liver specimens from individuals with NAFLD were examined to assess the expression of RNF186 and its associated factors.

RESULTS

Here, we provide evidence that depletion of RNF186 enhances lipophagy in hepatocytes of a NAFLD model. Mechanistically, RNF186 acts as an E3 ubiquitin ligase that targets cytoplasmic HMGB1 for lysine 48 (K48)- and K63-linked ubiquitination, leading to its subsequent proteasomal degradation. Importantly, the translocation of HMGB1 from the nucleus to the cytoplasm is responsible for inducing lipophagy in NAFLD samples. Knockdown of HMGB1 significantly reduces the activation of lipophagy and mediates the decrease in lipid accumulation caused by RNF186 depletion in hepatocytes. Furthermore, we find that maintaining the nuclear HMGB1 level and inhibiting its nuclear-cytoplasmic shuttling are critical for the proper function of RNF186 in NAFLD. Additionally, the expression of RNF186 and HMGB1 in human NAFLD samples, along with factors related to lipophagy, suggest that RNF186 may play a similar role in the pathogenesis of human fatty liver.

CONCLUSION

RNF186 deficiency accelerates hepatic lipophagy in NAFLD through the inhibition of ubiquitination and degradation of cytoplasmic HMGB1. Consequently, targeting the RNF186-HMGB1 axis may offer a promising strategy for the prevention and treatment of NAFLD.

The association of systemic inflammatory biomarkers with non-alcoholic fatty liver disease: a large population-based cross-sectional study

Purpose

The aim of this study was to explore the relationship between non-alcoholic fatty liver disease (NAFLD) and the two blood inflammatory markers including the systemic immune-inflammation (SII) index, and the system inflammation response index (SIRI).

Methods

The National Health and Nutrition Examination Survey data between the year of 2017-2018 was used for this cross-sectional study. In order to analyze the association of SII index, and SIRI and risk of NAFLD, we used multivariable logistic regression models, restricted cubic spline (RCS) plot, and subgroup analysis to analyze the data.

Results

In total, there were 1,199 individuals who participated in the survey. As shown by the RCS plot, SII index, and SIRI were linked with NAFLD risk in a U-shaped pattern. With regard to known confounding variables, when comparing the lowest quartile, the odds ratio with 95 % confidence interval for prevalence of NAFLD across the quartiles of SII index and SIRI were (0.89 (0.57, 1.41), 0.56 (0.35, 0.89) and 1.01 (0.64, 1.59)), and (0.77 (0.48, 1.23), 0.79 (0.50, 1.24) and 0.94 (0.60, 1.47)), respectively. Additionally, SII index, and SIRI and NAFLD risk also were U-curve correlated among the participants in age ≥60 years, female, without hypertension, and BMI of ≥30 kg/m2.

Conclusions

There was a U-shaped association of SII index and SIRI with prevalence of NAFLD, indicating that SII index and SIRI should be monitored dynamically.

Glucocorticoids and intrauterine programming of nonalcoholic fatty liver disease

Accumulating epidemiological and experimental evidence indicates that nonalcoholic fatty liver disease (NAFLD) has an intrauterine origin. Fetuses exposed to adverse prenatal environments (e.g., maternal malnutrition and xenobiotic exposure) are more susceptible to developing NAFLD after birth. Glucocorticoids are crucial triggers of the developmental programming of fetal-origin diseases. Adverse intrauterine environments often lead to fetal overexposure to maternally derived glucocorticoids, which can program fetal hepatic lipid metabolism through epigenetic modifications. Adverse intrauterine environments program the offspring's glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis, which contributes to postnatal catch-up growth and disturbs glucose and lipid metabolism. These glucocorticoid-driven programming alterations increase susceptibility to NAFLD in the offspring. Notably, after delivery, offspring often face an environment distinct from their in utero life. The mismatch between the intrauterine and postnatal environments can serve as a postnatal hit that further disturbs the programmed endocrine axes, accelerating the onset of NAFLD. In this review, we summarize the current epidemiological and experimental evidence demonstrating that NAFLD has an intrauterine origin and discuss the underlying intrauterine programming mechanisms, focusing on the role of overexposure to maternally derived glucocorticoids. We also briefly discuss potential early life interventions that may be beneficial against fetal-originated NAFLD.

Characteristics of contemporary drug clinical trials regarding the treatment of non-alcoholic steatohepatitis

BACKGROUND

Non-alcoholic steatohepatitis (NASH), a chronic liver disease, has no United States Food and Drug Administration (FDA) approved drugs for treatment.

OBJECTIVES

To examine fundamental characteristics of drug clinical trials for NASH treatment on the global clinical trials registry platform.

METHODS

Cross-sectional analysis of clinical trials with NASH as medical condition that are registered on ClinicalTrials.gov. Relevant trial entries registered before and on October 7th, 2022, were downloaded, deduplicated, and reviewed. NCT numbers, titles, locations, funder types, statuses, durations, study designs, subject information, conditions, interventions, outcome measures were extracted and analyzed.

RESULTS

Overall, 268 drug clinical trials were included in this study. Majority of the trials are conducted in United States (42.2 %). Most of the trials are funded by industry (67.9 %). The earliest initiated trials date back to 2001. Most trials are phase 2 (56.3 %), randomized (84.0 %), parallel assignment (78.7 %), and quadruple blind (40.3 %). The most concerned combined medical conditions are non-alcoholic fatty liver disease (NAFLD, 20.9 %). The most involved mechanisms of action drug categories are farnesoid X receptor (FXR) agonists and peroxisome proliferator-activated receptor (PPAR) agonists, with the most tested drugs being the FXR agonist EDP-305 and the Glucagon-like peptide-1 (GLP-1) agonist semaglutide.

CONCLUSION

Old drugs are further repurposed for testing in NASH treatment, novel drugs are developed to try to cure NASH. We expect that the drug clinical trials will accelerate the frontier of therapeutic development in NASH, bring an innovative and efficacious medication therapeutic approach to prevent the development and progression of NASH, or even reverse NASH.

Sarcopenia, sarcopenic obesity and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), sarcopenia and sarcopenic obesity (SO) are highly prevalent conditions that may coexist, especially in the aging population, without any approved pharmacologic treatment for all of them. There are multiple pathophysiologic mechanisms suggested to explain an association between NAFLD and sarcopenia or SO, including alterations in the adipokines, cytokines, hepatokines and myokines, which may interplay with other factors, such as aging, diet and physical inactivity. In clinical terms, most observational studies support an association between NAFLD and sarcopenia or SO; importantly, there are few cohort studies indicating higher mortality in patients with NAFLD and sarcopenia. Their association also bears some treatment considerations: for example, pioglitazone or vitamin E, suggested as off label treatment for selected patients with nonalcoholic steatohepatitis, may be recommended in the coexistence of sarcopenia or SO, since limited evidence did not show adverse effects of them on sarcopenia and abdominal obesity. In this review, evidence linking sarcopenia and SO with NAFLD is summarized, with a special focus on clinical data. A synopsis of the major pathophysiological links between NAFLD and sarcopenia/SO is initially presented, followed by selected clinical studies and, finally, treatment considerations in patients with NAFLD and sarcopenia or SO are discussed.

Design, synthesis, and biological studies of novel sulfonamide derivatives as farnesoid X receptor agonists

Farnesoid X receptor (FXR) is considered as a promising target for the treatment of NASH. Although many non-steroidal FXR agonists have been reported, the structure types are quite scarce and mainly limited to the isoxazole scaffold derived from GW4064. Therefore, it is crucial to expand the structure types of FXR agonist to explore wider chemical space. In this study, the structure-based scaffold hopping strategy was performed by hybrid FXR agonist 1 and T0901317, which resulted in the discovery of sulfonamide FXR agonist 19. Molecular docking study reasonably explained the SAR in this series, and compound 19 fitted well with the binding pocket in a similar mode to the co-crystal ligand. In addition, compound 19 exhibited considerable selectivity against other nuclear receptors. In NASH model, compound 19 alleviated the typical histological features of fatty liver, including steatosis, lobular inflammation, ballooning, and fibrosis. Moreover, compound 19 exhibited acceptable safety profiles with no acute toxicity to major organ. These results suggested that the novel sulfonamide FXR agonist 19 might be a promising agent for the treatment of NASH.

Puerarin alleviates nonalcoholic steatohepatitis by upregulating the Nrf2 pathway

BACKGROUND

The incidence of nonalcoholic steatohepatitis (NASH) is on the rise, and inflammation and oxidative stress play a key role in the progression of NASH. Puerarin has anti-inflammatory and antioxidant activity, but the effect and mechanism of action of puerarin on NASH need to be further explored.

AIM

To explore the effect and mechanisms of action of puerarin in the treatment of NASH.

METHODS

NASH was induced in C57BL/6 mice with a methionine and choline deficiency (MCD) diet. Mice were randomly divided into a normal diet group, a NASH model group, and a puerarin group. Each group were fed the corresponding diet for 4 wk. Serum and liver samples were collected to evaluate histological changes, inflammation, liver function, and oxidative stress.

RESULTS

Compared with the normal diet group, hepatic triglycerides and cholesterol were significantly increased in the NASH model group. Histological analysis showed that there was more significant fatty changes, inflammation, and fibrosis in the liver of mice in the NASH model group compared with those in the normal diet group. Compared with the normal diet group, glutathione and superoxide dismutase were significantly decreased, but malondialdehyde was significantly increased in the NASH model group. Compared with the NASH model group, serum triglycerides and cholesterol in the puerarin group were significantly reduced, and serum inflammatory factors (TNF-α and IL-1β) were significantly decreased in the puerarin group (P < 0.05). The mRNA expression of fibrosis-related genes (αSMA, PAI-1, COL1A1, and TGFβ) in the liver of mice in the puerarin group were sharply decreased compared with those in the NASH model group. Compared with the NASH model group, glutathione and superoxide dismutase were significantly increased in the puerarin group. Nuclear NF-E2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1) expression was significantly increased in the puerarin group compared with the NASH model group (P < 0.05).

CONCLUSION

Puerarin can significantly improve MCD diet-induced NASH. The mechanisms may be related to its anti-inflammation and anti-fibrosis effects and up-regulation of the Nrf2 pathway. Our study offers novel insights into the pathogenesis of NASH and provides further evidence for the potential use of puerarin as an anti-NASH agent.

Diosgenin alleviates nonalcoholic steatohepatitis through affecting liver-gut circulation

Nonalcoholic steatohepatitis (NASH), as the aggressive form of nonalcoholic fatty liver disease (NAFLD), rapidly becomes the leading cause of end-stage liver disease or liver transplantation. Nowadays, there has no approved drug for NASH treatment. Diosgenin possesses multiple beneficial effects towards inhibition of lipid accumulation, cholesterol metabolism, fibrotic progression and inflammatory response. However, there has been no report concerning its effects on NASH so far. Using methionine and choline-deficient (MCD) feeding mice, we evaluated the anti-NASH effects of diosgenin. 16 S rDNA was used to investigate gut microbiota composition. Transcriptome sequencing, LC/MS and GC/MS analysis were used to evaluate bile acids (BAs) metabolism and their related pathway. Compared with the MCD group, diosgenin treatment improved the hepatic dysfunction, especially decreased the serum and hepatic TC, TG, ALT, AST and TBA to nearly 50%. Content of BAs, especially CA and TCA, were decreased from 59.30 and 26.00-39.71 and 11.48 ng/mg in liver and from 0.96 and 2.1-0.47 and 1.13 μg/mL in serum, and increased from 7.01 and 11.08-3.278 and 5.11 ng/mg in feces, respectively. Antibiotic and fecal microbiota transplantation (FMT) treatment further confirmed the therapeutic effect of diosgenin on gut microbiota, especially Clostridia (LDA score of 4.94), which regulated BAs metabolism through the hepatic FXR-SHP and intestinal FXR-FGF15 pathways. These data indicate that diosgenin prevents NASH by altering Clostridia and BAs metabolism. Our results shed light on the mechanisms of diosgenin in treating NASH, which pave way for the design of novel clinical therapeutic strategies.

Efficacy and safety of acetyl-CoA carboxylase (ACC) inhibitors in the treatment of nonalcoholic steatohepatitis (NASH): A protocol for systematic review

BACKGROUND

The pathological mechanism of nonalcoholic steatohepatitis (NASH) is closely related to abnormal lipid regulation in hepatocytes. Patients with NASH generally have a significant increase in de novo lipogenesis, which acetyl-CoA carboxylase (ACC) catalyzes the first committed step. However, the treatment with ACC inhibitors remains controversial. Thus, our study will systematically evaluate the efficacy and safety of ACC inhibitors for the treatment of NASH.

METHODS

We plan to search PubMed, Cochrane Library, Web of Science, EMBASE, Google Scholar, ClinicalTrials.gov, China Science and Technology Journal Database, Chinese Biomedical Literature Database, Wan-fang Database and China National Knowledge Infrastructure to obtain literatures from January 2015 to January 2030 under the inclusion and exclusion criteria, and include randomized controlled trials containing intervention of ACC inhibitors for NASH. The proportion of patients with reduction in ballooning, inflammation and fibrosis will be accepted as the main outcome. RoB 2 will be used for the risk of bias, as well as Egger's test and funnel plot for reporting bias. We will adopt Review Manager 5.4.1 for data synthesis, subgroup analysis, meta-regression analysis and sensitivity analysis, and conduct trial sequential analysis and quality of evidence evaluation using trial sequential analysis 0.9.5.10 Beta software and GRADE Profiler 3.6.1 software respectively.

RESULTS

This systematic review will assess the proportion of patients with reduction of ballooning, inflammation and fibrosis, changes in hepatic steatosis, levels of liver enzymes and liver injury markers, metabolic parameters, safety and tolerability to measure the clinical benefits of ACC inhibitors for NASH.

CONCLUSION

The conclusion of this systematic review will achieve convincing evidence to evaluate the efficacy and safety of ACC inhibitors for NASH.