Progression Of Nonalcoholic Steatohepatitis Research Articles

The glycemic profile in patients with non-alcoholic steatohepatitis and type 2 diabetes depending on diabetic kidney disease

Background. State of carbohydrate metabolism and severity of insulin resistance in the comorbid course of non-alcoholic steatohepatitis (NASH) and diabetic kidney disease (DKD) in patients with type 2 diabetes mellitus (DM2) is due to the cascade of possible transformation of NASH into liver cirrhosis. The purpose is to study the interaction of changes in glucose and insulin homeostasis, the degree of insulin resistance and insulin sensitivity, the degree of hemoglobin glycosylation on the clinical course of NASH associated with DM depending on the presence of DKD and its stage. Materials and methods. One hundred and eight patients with NASH and comorbid DM2 were examined. The average age of patients was 58.2 ± 6.1 years. There were 63 women (58.3 %) and 45 men (41.7 %). Depending on the presence of DKD, 4 groups of patients were formed, who were randomized by age, sex, activity of cytolytic syndrome. The comparison group consisted of 30 healthy individuals of the appropriate age and sex. The degree of hepatic steatosis and its nature were determined using SteatoTest, ASH and NASH-Test kits (BioPredictive, France). The stage of liver fibrosis was determined using FibroTest (BioPredictive, France), a set of markers for quantitative biochemical evaluation of fibrosis. Results. In patients with NASH, DM2 and DKD stage I–II, we found a significant decrease in serum albumin by 9.0 % (p < 0.05); glomerular filtration rate (GFR) and urine albumin, on the contrary, increased significantly, by 1.5 times (p < 0.05) compared to those in the control group, which indicates the phenomenon of hyperfiltration and is specific to the initial stage of DKD. When NASH is combined with DM2 and DKD stage III, a significant decrease in serum albumin by 1.2 times (p < 0.05) is reported; GFR and albuminuria were significantly increased, by 1.4 and 11.7 times (p < 0.05), respectively, compared to the control group. In patients with NASH, DM2 and DKD stage IV, we found a significant decrease in serum albumin by 1.4 times (p < 0.05), it was significantly increased by 30.2 times (p < 0.05) compared to the indicator in the control group, and the GFR, on the contrary, was significantly reduced by 1.7 times (p < 0.05), which indicates the progression of DKD. Conclusions. Disorders of glucose homeostasis due to insulin resistance are one of the probable risk factors for the progression of non-alcoholic steatohepatitis and type 2 diabetes mellitus in the presence of stage I–IV diabetic kidney disease.

Genistein upregulates AHR to protect against environmental toxin-induced NASH by inhibiting NLRP3 inflammasome activation and reconstructing antioxidant defense mechanisms

We have previously proven that the environmental toxin could accelerate the development and progression of nonalcoholic steatohepatitis (NASH). However, the underlying mechanism associated with such excessive inflammation hasn't been fully illustrated. Although Genistein has been well accepted for its capability in anti-inflammation and anti-oxidation, its effect in ameliorating contaminants-induced NASH still needs to be identified. In this study, using chickens and primary chicken hepatocytes as models, we found that NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome were over-activated in bromoacetic acid (BAA, one of the typical environmental toxins)-induced NASH, characterized by the infiltration of inflammatory cell, and the increase of NLRP3, Caspase-1 p20, and cytokines (IL-1β, IL-18) expressions. Interestingly, genistein treatment could recover these changes, with the signs of restored activities of anti-oxidases, decreased expressions of NLRP3 inflammasome components, and increased levels of elements in phase I metabolic system. The detailed mechanism was that, via up-regulating aryl hydrocarbon receptor (AHR), genistein lifted mRNA levels of Cyp1-related genes to reconstruct cytochrome P450 (CYP450) systems, and the raised AHR negatively regulated NLRP3 inflammasome activity to relieve inflammation. More important, the interaction and co-localization between AHR and NLRP3 was first proved, and genistein could promote the levels of AHR that interacted with NLRP3, which thereafter blocked the activation of NLRP3 inflammasome. Conclusively, in this research, we confirmed the AHR-dependent protective role of genistein in environmental toxin-linked NASH, which shed light on the potential precautions for contaminants-induced NASH.

Role of microRNA in non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH): a comprehensive review.

Non-alcoholic fatty liver disease (NAFLD) is a prevalent liver condition that affects people who do not overconsume alcohol. Uncertainties exist over how microRNAs (miRNAs) in the blood and liver relate to NAFLD. The aim of this narrative review was to investigate the role of miRNAs in the onset and progression of non-alcoholic steatohepatitis (NASH) from NAFLD, and explore their potential as diagnostic tools and treatment targets for NAFLD patients. Liver miRNA-34a levels were found to accurately represent the degree of liver damage, with lower levels suggesting more damage. In patients with NAFLD and severe liver fibrosis, higher levels of miRNA-193a-5p and miRNA-378d were found. Moreover, miRNA-34a, miRNA-122, and miRNA-192 levels might aid in differentiating NASH from NAFLD. Similar to this, miRNA-21 and miRNA-27 levels in rats were able to distinguish between steatosis and steatohepatitis. High-fat diets enhanced the expression of 15 distinct miRNAs in rats, and there were substantial differences in the miRNA expression patterns between obese and lean people. The results from the present review imply that miRNA microarrays and sequencing may be helpful diagnostic tools, and miRNAs may be a possible treatment target for patients with NAFLD.

Circulating Citrate Is Associated with Liver Fibrosis in Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis.

Nonalcoholic fatty liver disease (NAFLD) is associated with mitochondrial damage. Circulating mitochondrial metabolites may be elevated in NAFLD but their associations with liver damage is not known. This study aimed to assess the association of key mitochondrial metabolites with the degree of liver fibrosis in the context of NAFLD and nonalcoholic steatohepatitis (NASH). Cross-sectional analyses were performed on two cohorts of biopsy-proven NAFLD and/or NASH subjects. The association of circulating mitochondrial metabolite concentrations with liver fibrosis was assessed using linear regression analysis. In the single-center cohort of NAFLD subjects (n = 187), the mean age was 54.9 ±13.0 years, 40.1% were female and 86.1% were White. Type 2 diabetes (51.3%), hypertension (43.9%) and obesity (72.2%) were prevalent. Those with high citrate had a higher proportion of moderate/significant liver fibrosis (stage F ≥ 2) (68.4 vs. 39.6%, p = 0.001) and advanced fibrosis (stage F ≥ 3) (31.6 vs. 13.6%, p = 0.01). Citrate was associated with liver fibrosis independent of age, sex, NAFLD activity score and metabolic syndrome (per 1 SD increase: β = 0.19, 95% CI: 0.03-0.35, p = 0.02). This association was also observed in a cohort of NASH subjects (n = 176) (β = 0.21, 95% CI: 0.07-0.36, p = 0.005). The association of citrate with liver fibrosis was observed in males (p = 0.005) but not females (p = 0.41). In conclusion, circulating citrate is elevated and associated with liver fibrosis, particularly in male subjects with NAFLD and NASH. Mitochondrial function may be a target to consider for reducing the progression of liver fibrosis and NASH.

Thyroid hormone receptor beta expression changes have a limited impact on non-alcoholic steatohepatitis progression

Thyroid hormone receptor beta expression changes have a limited impact on non-alcoholic steatohepatitis progression

Notch1 inhibits the mechanistic role of STING signaling to regulate hepatocyte lipophagy in nonalcoholic steatohepatitis

Objective: To study the mechanistic role of myeloid-specific Notch1 knockout inhibiting STING signaling to regulate hepatocyte lipophagy. Methods: A mouse model of nonalcoholic steatohepatitis (NASH) was established using a high-fat diet (HFD) and mouse bone marrow-derived macrophages (BMMs). Primary hepatocytes were isolated to construct a co-culture system. Twelve Notch1(FL/FL) mice were randomly divided into two groups: the Notch1(FL/FL) + normal diet (NCD) and the Notch1(FL/FL) + HFD group. Further, 12 Notch1(M-KO) mice were randomly divided into two groups: Notch1(M-KO) + NCD, and Notch1(M-KO) + HFD group.Serum alanine aminotransferase (sALT), total cholesterol (TC) and triglyceride (TG) were collected from mice serum samples. Liver tissue samples were collected for H&E staining, immunofluorescence (IF), Western blot and qRT-PCR. Tumor necrosis factor (TNF)-α was detected in the supernatant by enzyme-linked immunosorbent assay (ELISA). The comparison of inter group data was conducted using a t-test. Results: The mouse NASH model, mouse BMMs co-culture system, and primary hepatocytes were successfully constructed. Compared with the Notch1(FL/FL) + HFD group, the Notch1(M-KO) + HFD group showed a significant increase in serum ALT [(250.02 ± 58.21) U/L vs (370.70 ± 54.57) U/L, t = 3.705, P = 0.004], TG [(29.90 ± 3.54) mg/g vs (43.83 ± 8.56) mg/g, t = 3.685, P = 0.004], and TC [(33.70 ± 8.43) mg/g vs (90.53 ± 12.53) mg/g, t = 9.917, P < 0.001]. HE staining of liver tissue showed remarkable balloon-like alterations in liver cells, while IF staining demonstrated increased macrophage infiltration (t = 7.346, P < 0.001). Compared with the hepatocyte group co-cultured with Notch1(FL/FL) BMMs, the BODIPY probe showed a significant increase in lipid droplet (LDs) deposition in liver cells in the Notch1(M-KO) group (t = 3.835, P < 0.001). The co-localization of lysosomal associated membrane protein 1 (LAMP1), LDs (t = 7.103, P < 0.001), microtubule-associated protein light chain 3 (LC3) -II/LC3-I (t = 5.0, P = 0.007), and autophagy associated gene 12 (Atg12) (t = 28.36, P < 0.001) had decreased expression, while P-62 had increased expression (t = 3.253, P = 0.03), indicating a decrease in autophagic flow. Additionally, LC3 and LDs colocalization decreased (t = 5.24, P = 0.0003), indicating reduced lipophagy. Compared with the Notch1(FL/FL) group, the Notch1(M-KO) BMMS mouse group showed an increase in the expression of p-STING (t = 5.318, P = 0.006), p-TANK1 binding kinase 1 (TKB1) (t = 6.467, P = 0.002), p-interferon regulatory factor 3 (IRF3) (t = 14.61, P < 0.001), and p-P65 (t = 12.7, P = 0.002) protein, accompanied by mRNA expression of the inflammatory mediators interferon (IFN)-β (t = 7.978, P < 0.001), TNFα (t = 8.496, P = 0.001), interleukin-1 β (IL-1 β) (t = 4.7, P < 0.001), and CXCL-10 (t = 4.428, P = 0.001). The STING gene was knocked out in the BMMs Notch1(M-KO) mice using CRISPR/Cas9. Compared with the CRISPR-Control group, the expression of P-TKB1 (t = 2.909, P = 0.044), p-IRF3 (t = 10.96, P < 0.001), p-IRF3 (t = 10.96, P < 0.001), and p-P65 (t = 7.091, P = 0.002) proteins was lower in the STING-KO BMMs group. The release of TNF-α in the supernatant was decreased (732.3 ± 129.35 pg/ml vs. 398.17 ± 47.15 pg/ml, t = 4.204, P = 0.014). However, in hepatocytes co-cultured with STING-KO BMMs, LC3-II/LC3-I (t = 7.546, P = 0.001) increased, p-62 (t = 10.96, P < 0.001) expression decreased, autophagic flow increased, and the colocalization of LC3 and LDs increased, lipophagy increased, and LDs deposition decreased. Conclusion: Myeloid-specific Notch1 knockout can activate macrophages STING signaling, increase the expression of inflammatory mediator genes, inhibit the occurrence of autophagy flow and lipophagy in hepatocyte cells, and aggravate LDs deposition and NASH progression.

Nicotinic acid attenuates experimental non-alcoholic steatohepatitis by inhibiting the NLRP3 inflammasome/pyroptosis pathway

Non-alcoholic steatohepatitis (NASH) is a global public health concern that may progress into fibrosis, cirrhosis, and liver cancer, with limited curative treatment options. While the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is closely linked to NASH progression, nicotinic acid (NA), a vitamin used for the treatment of dyslipidemia, is an emerging pharmaceutical treatment for hepatic steatosis and fibrosis. Here, we investigated pharmacological effects of NA on experimental NASH and whether NLRP3 inflammasome/pyroptosis inhibition is an associated mechanism of action. Rats were fed a high-fat sucrose diet supplemented with cholesterol and a low dose of CCl4. NA significantly reduced inflammation by decreasing the protein levels of tumor necrosis factor-alpha and nuclear factor kappa B. Moreover, NA inhibited the formation of NLRP3- apoptosis-associated speck-like protein containing caspase recruitment domain-Caspase-1, decreasing interleukin-1beta, interleukin-18, and gasdermin D protein. In addition, NA reduced tumor growth factor-beta, alpha-smooth muscle actin, and hepatic levels of collagen-1, consequently decreasing extracellular matrix synthesis. Our results indicate that NA can inhibit NASH progression and encourage further basic and clinical studies on the use of NA for the treatment of human NASH.

Gossypetin prevents the progression of nonalcoholic steatohepatitis by regulating oxidative stress and AMP-activated protein kinase.

Nonalcoholic steatohepatitis (NASH) is severe liver metabolic disorder, however, there are still no effective and safe drugs for its treatment. Previous clinical trials used various therapeutic approaches to target individual pathological mechanisms, but these approaches were unsuccessful because of the complex pathological causes of NASH. Combinatory therapy in which two or more drugs are administered simultaneously to patients with NASH, however, it carries the risk of side effects associated with each individual drug. To solve this problem, we identified gossypetin as an effective dual-targeting agent that activates AMP-activated protein kinase (AMPK) and decreases oxidative stress. Administration of gossypetin decreased hepatic steatosis, lobular inflammation and liver fibrosis in the liver tissue of mice with CDHFD and MCD diet-induced NASH. Gossypetin functioned directly as anti-oxidant agents, decreasing hydrogen peroxide and palmitate-induced oxidative stress in the AML12 cells and liver tissue of MCD diet fed mice without regulating the antioxidant response factors. In addition, gossypetin acted as a novel AMPK activator by binding to the allosteric drug and metabolite (ADaM) site, which stabilizes the activated structure of AMPK. Our findings demonstrate that gossypetin has the potential to serve as a novel therapeutic agent for NAFLD/NASH. Significance Statement This study demonstrates that gossypetin has preventive effect to progression of NASH as a novel AMPK activator and antioxidants. Our findings implicate that simultaneous activation of AMPK and oxidative stress using gossypetin has the potential to serve as a novel therapeutic approach for NAFLD/NASH patients.

Current Clinical Trial Status and Future Prospects of PPAR-Targeted Drugs for Treating Nonalcoholic Fatty Liver Disease.

The number of patients with nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH) is increasing globally and is raising serious concerns regarding the increasing medical and economic burden incurred for their treatment. The progression of NASH to more severe conditions such as cirrhosis and hepatocellular carcinoma requires liver transplantation to avoid death. Therefore, therapeutic intervention is required in the NASH stage, although no therapeutic drugs are currently available for this. Several anti-NASH candidate drugs have been developed that enable treatment via the modulation of distinct signaling cascades and include a series of drugs targeting peroxisome proliferator-activated receptor (PPAR) subtypes (PPARα/δ/γ) that are considered to be attractive because they can regulate both systemic lipid metabolism and inflammation. Multiple PPAR dual/pan agonists have been developed but only a few of them have been evaluated in clinical trials for NAFLD/NASH. Herein, we review the current clinical trial status and future prospects of PPAR-targeted drugs for treating NAFLD/NASH. In addition, we summarize our recent findings on the binding modes and the potencies/efficacies of several candidate PPAR dual/pan agonists to estimate their therapeutic potentials against NASH. Considering that the development of numerous PPAR dual/pan agonists has been abandoned because of their serious side effects, we also propose a repositioning of the already approved, safety-proven PPAR-targeted drugs against NAFLD/NASH.

Differentially Expressed Genes in Response to a Squalene-Supplemented Diet Are Accurate Discriminants of Porcine Non-Alcoholic Steatohepatitis.

Squalene is the major unsaponifiable component of virgin olive oil, the fat source of the Mediterranean diet. To evaluate its effect on the hepatic transcriptome, RNA sequencing was carried out in two groups of male Large White x Landrace pigs developing nonalcoholic steatohepatitis by feeding them a high fat/cholesterol/fructose and methionine and choline-deficient steatotic diet or the same diet with 0.5% squalene. Hepatic lipids, squalene content, steatosis, activity (ballooning + inflammation), and SAF (steatosis + activity + fibrosis) scores were analyzed. Pigs receiving the latter diet showed hepatic squalene accumulation and twelve significantly differentially expressed hepatic genes (log2 fold change < 1.5 or <1.5) correlating in a gene network. These pigs also had lower hepatic triglycerides and lipid droplet areas and higher cellular ballooning. Glutamyl aminopeptidase (ENPEP) was correlated with triglyceride content, while alpha-fetoprotein (AFP), neutralized E3 ubiquitin protein ligase 3 (NEURL3), 2'-5'-oligoadenylate synthase-like protein (OASL), and protein phosphatase 1 regulatory inhibitor subunit 1B (PPP1R1B) were correlated with activity reflecting inflammation and ballooning, and NEURL3 with the SAF score. AFP, ENPEP, and PPP1R1B exhibited a remarkably strong discriminant power compared to those pathological parameters in both experimental groups. Moreover, the expression of PPP1R1B, TMEM45B, AFP, and ENPEP followed the same pattern in vitro using human hepatoma (HEPG2) and mouse liver 12 (AML12) cell lines incubated with squalene, indicating a direct effect of squalene on these expressions. These findings suggest that squalene accumulated in the liver is able to modulate gene expression changes that may influence the progression of non-alcoholic steatohepatitis.

Vinpocetine represses the progression of nonalcoholic steatohepatitis in mice by mediating inflammasome components via NF-κB signaling

BackgroundInflammasome activation is known to be involved in nonalcoholic steatohepatitis (NASH). Vinpocetine is a derivative of vincamine and is reported to suppress the activation of inflammasome. MethodsThis study explored the therapeutical potential of Vinpocetine on NASH. Mice were fed with a choline-deficient (MCD) or chow diet in the presence or absence of Vinpocetine for 8 weeks. H&E staining and biochemical assays were determined to evaluate the hepatic steatosis and fibrosis symptoms. In addition, primary hepatocytes and Kupffer cells were isolated and induced by MCD or lipopolysaccharides/cholesterol crystals with or without Vinpocetine. ELISAs, qPCR, and Western blotting were applied to determine the levels of NASH-related biomarkers in both in vivo mouse model and in vitro cell models. ResultsTreatment of Vinpocetine did not cause observable side effects against and MCD-induced cells and mouse NASH model. However, treatment of Vinpocetine ameliorated hepatic steatosis and fibrosis and suppressed the levels of alanine transaminase and aspartate transferase in the mouse NASH model. In addition, treatment of Vinpocetine suppressed the mRNA and protein levels of inflammasome components both in vitro and in vivo. ConclusionVinpocetine suppressed NASH in mice by mediating inflammasome components via nuclear factor κB signaling.

Antagonizing adipose tissue-derived exosome miR-103-hepatocyte phosphatase and tensin homolog pathway alleviates autophagy in non-alcoholic steatohepatitis: A trans-cellular crosstalk.

Obesity plays a vital role in the occurrence and development of non-alcoholic steatohepatitis (NASH). However, the underlining mechanism is still unclear, where adipose tissue (AT) derived exosomes may actively participate. MicroRNAs (miRNAs) are commonly secreted from exosomes for cell communication. Though the regulation of miR-103 on insulin sensitivity has been reported, the specific role of AT-derived exosomes miR-103 in NASH is still vague and further investigation may provide novel therapeutic choices. To determine the specific role of AT-derived exosomes miR-103 in developing NASH through various methods. The expression levels of miR-103 in the AT-derived exosomes and livers were detected and compared between NASH mice and control. The effect of miR-103 on NASH progression was also explored by antagonizing miR-103, including steatosis and inflammation degree changes. The interaction between miR-103 and the autophagy-related gene phosphatase and tensin homolog (PTEN) was confirmed by dual-luciferase reporter assay. The role of the interaction between miR-103 and PTEN on autophagy was verified in NASH-like cells. Finally, the effects of miR-103 from adipose-derived exosomes on NASH and autophagy were analyzed through animal experiments. The expression of miR-103 was increased in NASH mice, compared to the control, and inhibition of miR-103 could alleviate NASH. The results of the dual-luciferase reporter assay showed miR-103 could interact with PTEN. MiR-103-anta decreased p-AMPKa, p-mammalian target of rapamycin (mTOR), and p62 but increased the protein levels of PTEN and LC3-II/I and the number of autophagosomes in NASH mice. Similar results were also observed in NASH-like cells, and further experiments showed PTEN silencing inhibited the effect of miR-103-anta. AT derived-exosome miR-103 aggravated NASH and increased the expressions of p-AMPKa, p-mTOR, and p62 but decreased the protein levels of PTEN and LC3-II/I and the number of autophagosomes in mice. AT derived-exosome increased the levels of miR-103 in the liver, and miR-103 aggravated NASH. Mechanically, miR-103 could interact with PTEN and inhibit autophagy.

Palmitoyltransferase ZDHHC3 Aggravates Nonalcoholic Steatohepatitis by Targeting S-Palmitoylated IRHOM2.

Underestimation of the complexity of pathogenesis in nonalcoholic steatohepatitis (NASH) significantly encumbers development of new drugs and targeted therapy strategies. Inactive rhomboid protein 2 (IRHOM2) has a multifunctional role in regulating inflammation, cell survival, and immunoreaction. Although cytokines and chemokines promote IRHOM2 trafficking or cooperate with partner factors by phosphorylation or ubiquitin ligases-mediated ubiquitination to perform physiological process, it remains unknown whether other regulators induce IRHOM2 activation via different mechanisms in NASH progression. Here the authors find that IRHOM2 is post-translationally S-palmitoylated at C476 in iRhom homology domain (IRHD), which facilitates its cytomembrane translocation and stabilization. Fatty-acids challenge can directly promote IRHOM2 trafficking by increasing its palmitoylation. Additionally, the authors identify Zinc finger DHHC-type palmitoyltransferase 3 (ZDHHC3) as a key acetyltransferase required for the IRHOM2 palmitoylation. Fatty-acids administration enhances IRHOM2 palmitoylation by increasing the direct association between ZDHHC3 and IRHOM2, which is catalyzed by the DHHC (C157) domain of ZDHHC3. Meanwhile, a metabolic stresses-triggered increase of ZDHHC3 maintains palmitoylated IRHOM2 accumulation by blocking its ubiquitination, consequently suppressing its ubiquitin-proteasome-related degradation mediated by tripartite motif containing 31 (TRIM31). High-levels of ZDHHC3 protein abundance positively correlate with the severity of NASH phenotype in patient samples. Hepatocyte-specific dysfunction of ZDHHC3 significantly inhibits palmitoylated IRHOM2 deposition, therefore suppressing the fatty-acids-mediated hepatosteatosis and inflammation in vitro, as well as NASH pathological phenotype induced by two different high-energy diets (HFHC & WTDF) in the in vivo rodent and rabbit model. Inversely, specific restoration of ZDHHC3 in hepatocytes markedly provides acceleration over the course of NASH development via increasing palmitoylation of IRHOM2 along with suppression of ubiquitin degradation. The current work uncovers that ZDHHC3-induced palmitoylation is a novel regulatory mechanism and signal that regulates IRHOM2 trafficking, which confers evidence associating the regulation of palmitoylation with NASH progression.

Schisandra lignans ameliorate nonalcoholic steatohepatitis by regulating aberrant metabolism of phosphatidylethanolamines.

Nonalcoholic steatohepatitis (NASH) is a spectrum of chronic liver disease characterized by hepatic lipid metabolism disorder. Recent reports emphasized the contribution of triglyceride and diglyceride accumulation to NASH, while the other lipids associated with the NASH pathogenesis remained unexplored. The specific purpose of our study was to explore a novel pathogenesis and treatment strategy of NASH via profiling the metabolic characteristics of lipids. Herein, multi-omics techniques based on LC-Q-TOF/MS, LC-MS/MS and MS imaging were developed and used to screen the action targets related to NASH progress and treatment. A methionine and choline deficient (MCD) diet-induced mouse model of NASH was then constructed, and Schisandra lignans extract (SLE) was applied to alleviate hepatic damage by regulating the lipid metabolism-related enzymes CES2A and CYP4A14. Hepatic lipidomics indicated that MCD-diet led to aberrant accumulation of phosphatidylethanolamines (PEs), and SLE could significantly reduce the accumulation of intrahepatic PEs. Notably, exogenous PE (18:0/18:1) was proved to significantly aggravate the mitochondrial damage and hepatocyte apoptosis. Supplementing PE (18:0/18:1) also deteriorated the NASH progress by up regulating intrahepatic proinflammatory and fibrotic factors, while PE synthase inhibitor exerted a prominent hepatoprotective role. The current work provides new insights into the relationship between PE metabolism and the pathogenesis of NASH.

Macrophage heterogeneity role in NAFLD and NASH disease progression

Nonalcoholic fatty liver disease (NAFLD) is a type of metabolic stress liver injury that is closely associated with insulin resistance and genetic susceptibility. The continuum of liver injury in NAFLD can range from nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH) and even lead to cirrhosis and liver cancer. The pathogenesis of NAFLD is complicated. Pro-inflammatory cytokines, lipotoxicity, and gut bacterial metabolites play a key role in activating liver-resident macrophages (Kupffer cells, KCs) and recruiting circulating monocyte-derived macrophages (MoDMacs) to deposit fat in the liver. With the application of single-cell RNA-sequencing, significant heterogeneity in hepatic macrophages has been revealed, suggesting that KCs and MoDMacs located in the liver exert distinct functions in regulating liver inflammation and NASH progression. This study focuses on the role of macrophage heterogeneity in the development and occurrence of NAFLD and NASH, in view of the fact that innate immunity plays a key role in the development of NAFLD.

Downregulation of microRNA-145a-5p promotes steatosis-to-NASH progression through upregulation of Nr4a2

The molecular mechanisms underlying the progression of simple steatosis to non-alcoholic steatohepatitis (NASH) remain incompletely understood, though the potential role of epigenetic regulation by microRNA (miRNAs) is an area of increasing interest. In the present study, we aimed to investigate the role and mechanism of miRNAs during steatosis-to-NASH progression. miR-145a-5p was identified as an important checkpoint in steatosis-to-NASH progression. Invivo loss-of-function and gain-of-function studies were performed to explore the role of miR-145a-5p and Nr4a2 in NASH progression. RNA-sequencing and bioinformatic analysis were used to investigate the targets of miR-145a-5p. Suppression of miR-145a-5p in the liver aggravated lipid accumulation and activated hepatic inflammation, liver injury and fibrosis in steatotic mice, whereas its restoration markedly attenuated diet-induced NASH pathogenesis. Mechanistically, miR-145a-5p was able to downregulate the nuclear receptor Nr4a2 and thus inhibit the expression of NASH-associated genes. Similarly, Nr4a2 overexpression promoted steatosis-to-NASH progression while liver-specific Nr4a2 knockout mice were protected from diet-induced NASH. This role of the miR-145a-5p/Nr4a2 regulatory axis was also confirmed in primary human hepatocytes. Furthermore, the expression of miR-145a-5p was reduced and the expression of Nr4a2 was increased in the livers of patients with NASH, while their expression levels significantly negatively and positively correlated with features of liver pathology, respectively. Our findings highlight the role of the miR-145a-5p/Nr4a2 regulatory axis in steatosis-to-NASH progression, suggesting that either supplementation of miR-145a-5p or pharmacological inhibition of Nr4a2 in hepatocytes may provide a promising therapeutic approach for the treatment of NASH. Non-alcoholic fatty liver disease (NAFLD) is a dynamic spectrum of chronic liver diseases ranging from simple steatosis to non-alcoholic steatohepatitis (NASH). Unfortunately, there are currently no approved drugs for NASH. Our current study identified miR-145a-5p as a novel regulator that inhibits steatosis-to-NASH progression. We found that miR-145a-5p was able to downregulate the nuclear receptor Nr4a2 to suppress the expression of NASH-associated genes. The differential expression of miR-145a-5p and Nr4a2 was further confirmed in patients with NASH, raising the possibility that supplementation of miR-145a-5p or suppression of Nr4a2 in hepatocytes might provide novel strategies for treating NASH.

Liver lipophagy ameliorates nonalcoholic steatohepatitis through extracellular lipid secretion

Nonalcoholic steatohepatitis (NASH) is a progressive disorder with aberrant lipid accumulation and subsequent inflammatory and profibrotic response. Therapeutic efforts at lipid reduction via increasing cytoplasmic lipolysis unfortunately worsens hepatitis due to toxicity of liberated fatty acid. An alternative approach could be lipid reduction through autophagic disposal, i.e., lipophagy. We engineered a synthetic adaptor protein to induce lipophagy, combining a lipid droplet-targeting signal with optimized LC3-interacting domain. Activating hepatocyte lipophagy in vivo strongly mitigated both steatosis and hepatitis in a diet-induced mouse NASH model. Mechanistically, activated lipophagy promoted the excretion of lipid from hepatocytes, thereby suppressing harmful intracellular accumulation of nonesterified fatty acid. A high-content compound screen identified alpelisib and digoxin, clinically-approved compounds, as effective activators of lipophagy. Administration of alpelisib or digoxin in vivo strongly inhibited the transition to steatohepatitis. These data thus identify lipophagy as a promising therapeutic approach to prevent NASH progression.

Targeting Endothelial Necroptosis Disrupts Profibrotic Endothelial-Hepatic Stellate Cells Crosstalk to Alleviate Liver Fibrosis in Nonalcoholic Steatohepatitis.

Chronic liver diseases affect over a billion people worldwide and often lead to fibrosis. Nonalcoholic steatohepatitis (NASH), a disease paralleling a worldwide surge in metabolic syndromes, is characterized by liver fibrosis, and its pathogenesis remains largely unknown, with no effective treatment available. Necroptosis has been implicated in liver fibrosis pathogenesis. However, there is a lack of research on necroptosis specific to certain cell types, particularly the vascular system, in the context of liver fibrosis and NASH. Here, we employed a mouse model of NASH in combination with inducible gene knockout mice to investigate the role of endothelial necroptosis in NASH progression. We found that endothelial cell (EC)-specific knockout of mixed lineage kinase domain-like protein (MLKL), a critical executioner involved in the disruption of cell membranes during necroptosis, alleviated liver fibrosis in the mouse NASH model. Mechanistically, EC-specific deletion of Mlkl mitigated the activation of TGFβ/Smad 2/3 pathway, disrupting the pro-fibrotic crosstalk between endothelial cells and hepatic stellate cells (HSCs). Our findings highlight endothelial MLKL as a promising molecular target for developing therapeutic interventions for NASH.

Endothelial autophagy is not required for liver regeneration after partial hepatectomy in mice with fatty liver.

Patients with non-alcoholic fatty liver disease (NAFLD) have impaired liver regeneration. Liver endothelial cells play a key role in liver regeneration. In non-alcoholic steatohepatitis (NASH), liver endothelial cells display a defect in autophagy, contributing to NASH progression. We aimed to determine the role of endothelial autophagy in liver regeneration following liver resection in NAFLD. First, we assessed autophagy in primary endothelial cells from wild type mice fed a high fat diet and subjected to partial hepatectomy. Then, we assessed liver regeneration after partial hepatectomy in mice deficient (Atg5lox/lox ;VE-cadherin-Cre+ ) or not (Atg5lox/lox ) in endothelial autophagy and fed a high fat diet. The role of endothelial autophagy in liver regeneration was also assessed in ApoE-/- hypercholesterolemic mice and in mice with NASH induced by methionine- and choline-deficient diet. First, autophagy (LC3II/protein) was strongly increased in liver endothelial cells following hepatectomy. Then, we observed at 40 and 48 h and at 7 days after partial hepatectomy, that Atg5lox/lox ;VE-cadherin-Cre+ mice fed a high fat diet had similar liver weight, plasma AST, ALT and albumin concentration, and liver protein expression of proliferation (PCNA), cell-cycle (Cyclin D1, BrdU incorporation, phospho-Histone H3) and apoptosis markers (cleaved Caspase-3) as Atg5lox/lox mice fed a high fat diet. Same results were obtained in ApoE-/- and methionine- and choline-deficient diet fed mice, 40 h after hepatectomy. These results demonstrate that the defect in endothelial autophagy occurring in NASH does not account for the impaired liver regeneration occurring in this setting.

Parabacteroides distasonis uses dietary inulin to suppress NASH via its metabolite pentadecanoic acid

Non-alcoholic steatohepatitis (NASH) is the severe form of non-alcoholic fatty liver disease, and is characterized by liver inflammation and fat accumulation. Dietary interventions, such as fibre, have been shown to alleviate this metabolic disorder in mice via the gut microbiota. Here, we investigated the mechanistic role of the gut microbiota in ameliorating NASH via dietary fibre in mice. Soluble fibre inulin was found to be more effective than insoluble fibre cellulose to suppress NASH progression in mice, as shown by reduced hepatic steatosis, necro-inflammation, ballooning and fibrosis. We employed stable isotope probing to trace the incorporation of 13C-inulin into gut bacterial genomes and metabolites during NASH progression. Shotgun metagenome sequencing revealed that the commensal Parabacteroides distasonis was enriched by 13C-inulin. Integration of 13C-inulin metagenomes and metabolomes suggested that P. distasonis used inulin to produce pentadecanoic acid, an odd-chain fatty acid, which was confirmed in vitro and in germ-free mice. P. distasonis or pentadecanoic acid was protective against NASH in mice. Mechanistically, inulin, P. distasonis or pentadecanoic acid restored gut barrier function in NASH models, which reduced serum lipopolysaccharide and liver pro-inflammatory cytokine expression. Overall this shows that gut microbiota members can use dietary fibre to generate beneficial metabolites to suppress metabolic disease.