The deubiquitinating enzyme 13 retards non-alcoholic steatohepatitis via blocking inactive rhomboid protein 2-dependent pathway

Nowadays potential preclinical drugs for the treatment of nonalcoholic steatohepatitis (NASH) have failed to achieve expected therapeutic efficacy because the pathogenic mechanisms are underestimated. Inactive rhomboid protein 2 (IRHOM2), a promising target for treatment of inflammation-related diseases, contributes to deregulated hepatocyte metabolism-associated nonalcoholic steatohepatitis (NASH) progression. However, the molecular mechanism underlying Irhom2 regulation is still not completely understood. In this work, we identify the ubiquitin-specific protease 13 (USP13) as a critical and novel endogenous blocker of IRHOM2, and we also indicate that USP13 is an IRHOM2-interacting protein that catalyzes deubiquitination of Irhom2 in hepatocytes. Hepatocyte-specific loss of the Usp13 disrupts liver metabolic homeostasis, followed by glycometabolic disorder, lipid deposition, increased inflammation, and markedly promotes NASH development. Conversely, transgenic mice with Usp13 overexpression, lentivirus (LV)- or adeno-associated virus (AAV)-driven Usp13 gene therapeutics mitigates NASH in 3 models of rodent. Mechanistically, in response to metabolic stresses, USP13 directly interacts with IRHOM2 and removes its K63-linked ubiquitination induced by ubiquitin-conjugating enzyme E2N (UBC13), a ubiquitin E2 conjugating enzyme, and thus prevents its activation of downstream cascade pathway. USP13 is a potential treatment target for NASH therapy by targeting the Irhom2 signaling pathway.

Relação monócito/HDL em esteatose não hepática / Monocyte/hdl ratio in non-alcoholic hepatic steatosis

ABSTRACT BACKGROUND: Non-alcoholic hepatic steatosis (NAS) is characterized by excess fat accumulation in hepatocytes, causing portal and lobular inflammation and hepatocyte injury. OBJECTIVE: We aimed to evaluate the alterations in monocyte count to high-density lipoprotein cholesterol ratio (MHR) in patients with grade 2 or 3 fatty liver disease and the association of this marker with liver function tests and insulin resistance. METHODS: In this retrospective analysis; patients diagnosed and followed for the grade 2 or 3 fatty liver disease were included in the patient group and the patients who had undergone abdominal ultrasound for any reason and who were not having any fatty liver disease were included in the control group. RESULTS: Totally 409 cases were included in the study. Among participants, 201 were in the control group, and 208 were in the NAS group (111 were having grade 2 and 97 were having grade 3 steatosis). The monocyte/HDL ratio was significantly higher in the NAS group compared with the healthy controls (P=0.001). There was a significant positive correlation between the monocyte/HDL ratio and age (r=0.109; P=0.028), ALT (r=0.123, P=0.014) and HOMA-IR (r=0.325, P=0.001) values. CONCLUSION: In conclusion, the monocyte to high-density lipoprotein ratio significantly increases in fatty liver disease and correlates with insulin resistance. Since it was suggested as a prognostic marker in atherosclerotic diseases, elevated MHR values in fatty liver disease should be evaluated cautiously.

RESUMO CONTEXTO: A esteatose não hepática (ENH) é caracterizada pelo acúmulo de gordura nos hepatócitos, causando inflamação portal e lobular e lesões ao hepatócito. OBJETIVO: Avaliar as alterações na contagem de monócitos em relação à proporção de lipoproteína de colesterol de alta densidade (MHR) em doentes com doença hepática gordurosa de grau 2 ou 3 e a associação deste marcador com testes de função hepática e de resistência à insulina. MÉTODOS: Nesta análise retrospectiva os pacientes diagnosticados e seguidos para a doença hepática gordurosa de grau 2 ou 3, foram incluídos no grupo de doentes e os indivíduos que tinham sido submetidos a ecografia abdominal por qualquer motivo e que não tinham qualquer doença hepática gordurosa foram incluídos no de controle. RESULTADOS: Foram incluídos 409 pacientes no estudo. Entre os participantes, 201 estavam no grupo controle e 208 estavam no grupo ENH (111 caracterizados como grau 2 e 97 com esteatose de grau 3). A relação monócito/HDL foi significativamente maior no grupo ENH em comparação com os controles saudáveis (P=0,001). Verificou-se correlação positiva significativa entre a relação monócitos/HDL e a idade (r=0,109; P=0,028), e valores de ALT (r=0,123; P=0,014) e HOMA-IR (r=0,325; P=0,001). CONCLUSÃO: A razão entre monócitos e a lipoproteína de alta densidade aumenta significativamente na doença hepática gordurosa e correlaciona-se com a resistência à insulina. Uma vez que foi sugerido como um marcador prognóstico em doenças ateroscleróticas, os valores elevados de MHR na doença hepática gordurosa devem ser avaliados com cautela.

α, ß-Amyrin prevents steatosis and insulin resistance in a high-fat diet-induced mouse model of NAFLD via the AMPK-mTORC1-SREBP1 signaling mechanism

Nonalcoholic fatty liver disease (NAFLD), characterized by hepatosteatosis and steatohepatitis, is intrinsically related to obesity. Our previous study reported on the anti-obese activity of α,β-amyrin (AMY), a pentacyclic triterpene isolated from Protium heptaphyllum. This study investigated its ability to prevent fatty liver and the underlying mechanism using the mouse model of NAFLD. NAFLD was induced in male Swiss mice fed a high fat diet (HFD) for 15 weeks. The controls were fed a normal chow diet (ND). The mice were simultaneously treated with AMY at 10 and 20 mg/kg or fenofibrate at 50 mg/kg. Lipid levels along with metabolic and inflammatory parameters were assessed in liver and serum. The liver sections were histologically examined using H&E staining. RT-qPCR and western blotting assays were performed to analyze signaling mechanisms. Mice fed HFD developed severe hepatic steatosis with elevated triglycerides and lipid droplets compared with ND controls. This was associated with a decrease in AMP-activated protein kinase (AMPK) activity, an increase of mechanistic target of rapamycin complex 1 (mTORC1) signaling, and enhanced sterol regulatory element binding protein 1 (SREBP1) expression, which have roles in lipogenesis, inhibition of lipolysis, and inflammatory response. AMY treatment reversed these signaling activities and decreased the severity of hepatic steatosis and inflammatory response, evidenced by serum and liver parameters as well as histological findings. AMY-induced reduction in hepatic steatosis seemed to involve AMPK-mTORC1-SREBP1 signaling pathways, which supported its beneficial role in the prevention and treatment of NAFLD.

Pleurotus citrinopileatus alleviates alcohol-induced fatty liver via upregulating AMPK signaling / 中国药理学与毒理学杂志

OBJECTIVE The current study was designed to investigate the anti-steatosis effect of Pleurotus citrinopileatus extract (PC) and the underlying mechanism in vivo and in vitro. METHODS Acute and chronic alcoholic hepatosteatosis murine models and ethanol-treated HepG2 cells were applied. RESULTS In vitro,the anti-steatosis effect of PC was further confirmed via Nile red staining in HepG2 cells treated with ethanol.Both of acute and chronic alcohol-induced mice hepatosteatosis model,PC decreased serum aminotransferase and triglyceride accumulation. Upregulated sterol-regulatory element binding protein1(Srebp1),purinergic ligand-gated ion channel 7receptor(P2X7R)and downregulated sirtuin1 (SIRT1), adenosine 5′-monophosphate (AMP)-activated protein kinase α (AMPKα) caused by acute and chronic alcohol intake were modulated by PC.In ethanol-exposed HepG2 cells,PC reduced lipid accumulation in a concentration-dependent manner and exhibited superior ability in controlling lipid accumulation compared with metformin. CONCLUSION PC could abolish hepatic lipid accumulation through regulating SIRT1-AMPKα signaling in acute and chronic alcohol-induced hepatic steatosis.

Gentiopicroside ameliorates LKB1/AMPK-dependent alcoholic hepatosteatosis via P2x7R-NLRP3 inflammasome / 中国药理学与毒理学杂志

OBJECTIVE Regulating P2x7R- NLRP3 inflammasome activation might be a potentialtherapeutic strategy to treat alcoholic hepatosteatosis. We investigated whether this process would be modulated by gentiopicroside (GPS), which is attributed to the bitterness of gentian root extract. METHODSAn in vivo model was established by intragastrically treating mice with ethanol, and an in vitro modelwas created by treating HepG2 cells with ethanol or treating RAW 264.7 macrophages and murinebone marrow- derived macrophages (BMDMs) with lipopolysaccharides (LPS) plus adenosine triphos-phate (ATP). RESULTS In alcoholic hepatosteatotic mice model, GPS decreased serum aminotrans-ferase and triglyceride accumulation. GPS regulated sterol regulatory element-binding protein-1 (Srebp1),peroxisome proliferators- actived receptors α (PPARα) and acetyl CoA carboxylase (ACC) expressionvia elevating liver kinase B1 (LKB1)/AMP-activated Kinase (AMPK). Suppression of nucleotide-bindingoligomerization domain-like receptor protein 3 (NLRP3), caspase-1 and expression by GPS resulted inthe inhibition of interleukin-1β (IL-1β) production. In ethanol-exposed HepG2 cells, GPS reduced lipo-genesis and promoted lipid oxidation via P2x7R- NLRP3 inflammasome activation. P2x7R silencingenhanced AMPK activity, and reduced Srebp1 expression in ethanol-treated hepatocytes. GPS down-regulated P2x7R-mediated inflammatory response to extracellular ATP in LPS-primed RAW 264.7 macro-phages and BMDMs. Additionally, P2x7R deficiency attenuated IL- 1β cleavage in RAW 264.7 macro-phages, and GPS further suppressed IL-1β cleavage. CONCLUSION Activation of LKB1/AMPK signalingby GPS might be mediated by P2x7R-NLRP3 inflammasome, suggesting a therapeutic utility of P2x7Rblockade in alcoholic hepatosteatosis treatment.

Renal protective effect of Ganoderma lucidum / 中国药理学与毒理学杂志

OBJECTIVE Non-alcoholic fatty liver disease(NAFLD) encompasses a series of patho-logic changes ranging from steatosis to steatohepatitis,which may progress to cirrhosis and hepatocel-lular carcinoma.The purpose of this study was to determine whether Ganoderma lucidum polysaccha-ride peptide (GLPP) has therapeutic effect on NAFLD. METHODS ob/ob mouse model and ApoC3 transgenic mouse model were used for exploring the effect of GLPP on NAFLD. Key metabolic path-ways and enzymes were identified by metabolomics combining with KEGG and PIUmet analyses and key enzymes were detected by Western blotting. Hepatosteatosis models of HepG2 cells and primary hepatocytes were used to further confirm the therapeutic effect of GLPP on NAFLD. RESULTS GLPP administrated for a month alleviated hepatosteatosis, dyslipidemia, liver dysfunction and liver insulin resistance. Pathways of glycerophospholipid metabolism, fatty acid metabolism and primary bile acid biosynthesis were involved in the therapeutic effect of GLPP on NAFLD. Detection of key enzymes revealed that GLPP reversed low expression of CYP7A1,CYP8B1,FXR,SHP and high expression of FGFR4 in ob/ob mice and ApoC3 mice. Besides, GLPP inhibited fatty acid synthesis by reducing the expression of SREBP1c, FAS and ACC via a FXR-SHP dependent mechanism. Additionally, GLPP reduced the accumulation of lipid droplets and the content of TG in HepG2 cells and primary hepato-cytes induced by oleic acid and palmitic acid. CONCLUSION GLPP significantly improves NAFLD via regulating bile acid synthesis dependent on FXR-SHP/FGF pathway, which finally inhibits fatty acid synthesis,indicating that GLPP might be developed as a therapeutic drug for NAFLD.

The association of vitamin D deficiency with non-alcoholic fatty liver disease

OBJECTIVE: Vitamin D deficiency has been related to diabetes, hypertension, hyperlipidemia and peripheral vascular disease. In this study, we aimed to investigate the role of vitamin D status in non-alcoholic fatty liver disease. METHODS: We included 211 consecutive subjects to examine the presence of non-alcoholic fatty liver disease. Of these subjects, 57 did not have non-alcoholic fatty liver disease and 154 had non-alcoholic fatty liver disease. RESULTS: The non-alcoholic fatty liver disease group had significantly higher fasting blood glucose (p = 0.005), uric acid (p = 0.001), aspartate aminotransferase (p<0.001), alanine aminotransferase (p<0.001), γ-glutamyltransferase (p<0.0001), alkaline phosphatase (p = 0.028), HbA1c (p<0.001), ferritin (p<0.001), insulin (p = 0.016), C-peptide (p = 0.001), HOMA-IR (p = 0.003), total cholesterol (p = 0.001), triglyceride (p = 0.001) and white blood cell (p = 0.04) levels. In contrast, the non-alcoholic fatty liver disease group had significantly lower 25(OH)D levels (12.3±8.9 ng/dl, p<0.001) compared with those of the control group (20±13.6 ng/dl). CONCLUSIONS: In this study, we found lower serum 25(OH)D levels in patients with non-alcoholic fatty liver disease than in subjects without non-alcoholic fatty liver disease. To establish causality between vitamin D and non-alcoholic fatty liver disease, further interventional studies with a long-term follow-up are needed. .