Statins Increase Mitochondrial and Peroxisomal Fatty Acid Oxidation in the Liver and Prevent Non-Alcoholic Steatohepatitis in Mice

Atorvastatin ameliorates α-KGDH and GDH functions in rats with diet-induced hypercholesterolemia

BACKGROUND

α-ketoglutarate dehydrogenase complex (α-KGDH) belongs to mitochondrial 2-oxoacid dehydrogenases family and is the key regulatory enzyme of cell metabolism. It is functionally interconnected with glutamate dehydrogenase (GDH) which is a source of α-KG, a substrate for α-KGDH. Our previous studies demonstrated that simvastatin had an influence on 2-oxoacid dehydrogenases, including α-KGDH. Hence, we hypothesised that atorvastatin, one of the most commonly prescribed lipid-lowering drugs, may modify liver α-KGDH and GDH.

OBJECTIVES

The purpose of the present study was to evaluate the effect of atorvastatin on liver α-KGDH and GDH in rats with diet-induced hypercholesterolemia.

METHODS

Atorvastatin at dose 20 mg/kg b.wt. (HC + A group, n = 10) or vehicle (HC group, hypercholesterolemic control, n = 10) were administered to rats with hypercholesterolemia for 21 days. The normal control group was fed a standard diet (ST group, normal control, n = 10). α-KGDH and GDH activities as well as their protein levels were determined. Moreover, serum parameters of lipid profile and liver function were measured.

RESULTS

Liver α-KGDH and GDH activities were lower in HC than in ST rats. Atorvastatin enhanced the inhibited activities of α-KGDH and GDH. Stimulation of α-KGDH and GDH by atorvastatin did not correspond with the increase in protein levels of these enzymes indicating that atorvastatin activated α-KGDH and GDH most likely via post-translational mechanism. Atorvastatin had a beneficial effect on serum lipid profile and did not change the parameters of liver function.

CONCLUSION

The present study demonstrated that atorvastatin ameliorated liver α-KGDH and GDH functions in rats with diet-induced hypercholesterolemia.

Statins and non-alcoholic fatty liver disease: A concise review

Non-alcoholic fatty liver disease (NAFLD) is a common hepatic manifestation of metabolic syndrome affecting 20-30 % of the adult population worldwide. This disease, which includes simple steatosis and non-alcoholic steatohepatitis, poses a significant risk for cardiovascular and metabolic diseases. Lifestyle modifications are crucial in the treatment of NAFLD; however, patient adherence remains challenging. As there is no specific treatment, drug repositioning is being researched as an alternative strategy. Statins, which are known for their cholesterol-lowering effects, are considered potential interventions for NAFLD. This review aimed to present the current understanding of the effects of statins on liver physiology in the context of NAFLD. The pathophysiology of NAFLD includes steatosis, inflammation, and fibrosis, which are exacerbated by dyslipidemia and insulin resistance. Statins, which inhibit 3-hydroxy-3-methylglutaryl-CoA reductase, have pleiotropic effects beyond cholesterol-lowering and affect pathways related to inflammation, fibrogenesis, oxidative stress, and microcirculation. Although clinical guidelines support the use of statins for dyslipidemia in patients with NAFLD, more studies are needed to demonstrate their efficacy in liver disease. This comprehensive review serves as a foundation for future studies on the therapeutic potential of statins in NAFLD.

Direct and transgenerational effects of simvastatin on the metabolism of the amphipod Gammarus locusta

In this study, untargeted Nuclear Magnetic Resonance (NMR) metabolomics was applied for the first time, to our knowledge, to assess the metabolic impact of direct and transgenerational exposure (F0 and F3 generations, respectively) of amphipods Gammarus locusta to simvastatin (SIM), a pharmaceutical widely prescribed for the treatment of hypercholesterolemia. Results revealed the important gender-dependent nature of each of these effects. Directly exposed males showed enhanced glucose catabolism and tricarboxylic acid (TCA) cycle activity, in tandem with adaptations in osmotic regulation and glyoxylate metabolism. Exposed females exhibited only a small osmoregulatory effect. It is suggested that the response of exposed males may reflect reported high levels of methyl farnesoate hormone (low levels in females) and alterations in apical factors, namely decreased growth. Conversely, transgenerational effects were identified only in females, with impact on energy metabolism (glycolysis and TCA cycle enhancement) and osmoregulatory response. This expresses the ability of female gametes to transmit the effects of direct SIM exposure. Such effects were putatively related to reported delayed maturation and transcriptomic deviations impacting on carbohydrate and lipid metabolisms, possibly specifically engaging phenylalanine/tyrosine and choline in dopamine and choline metabolisms. These findings reflect the importance of untargeted metabolomics in addressing not only direct exposure of contaminants, but also their transgenerational effects, potentially contributing towards improving hazard and risk assessment of biologically active compounds.

Statins as a Potential Treatment for Non-alcoholic Fatty Liver Disease: Target Deconvolution using Protein-protein Interaction Network Analysis

BACKGROUND

The hallmark of non-alcoholic fatty liver disease (NAFLD) is aberrant buildup of triglycerides (TGs) in hepatocytes. Many genes promote NAFLD development. Using bioinformatics tools, we investigated the possible effect of statins on genes involved in NAFLD progression.

METHODS

Protein interactions of statins and NAFLD were searched in gene-drug and gene-disease databases. A Protein-Protein interaction (PPI) network was constructed to find hub genes and Molecular Complex Detection (MCODE) of NAFLD-related genes. Shared protein targets between protein targets of statins and NAFLD-associated genes were identified. Next, targets of each statin were assayed with all modular clusters in the MCODEs related to NAFLD. Biological process and pathway enrichment analysis for shared proteins was performed.

RESULTS

Screening protein targets for conventional statins and curated NAFLD-related genes identified 343 protein targets and 70 genes, respectively. A Venn diagram of NAFLD-related genes and protein targets of statins showed 24 shared proteins. The biological pathways on KEGG enrichment associated with the 24 shared protein sets were evaluated and included cytokine-cytokine receptor interaction, adipocytokine, PPAR, TNF and AMPK signaling pathways. Gene Ontology analysis showed major involvement in lipid metabolic process regulation and inflammatory response. PPI network analysis of 70 protein targets indicated 13 hub genes (PPARA, IL4, CAT, LEP, SREBF1, PRKCA, CYP2E1, NFE2L2, PTEN, NR1H4, ADIPOQ, GSTP1 and TGFB1). Comparing all seven statins with the three MCODE clusterings and 13 hub genes revealed that simvastatin as the most associated statin with NAFLD.

CONCLUSION

Simvastatin has the most impact on NAFLD-related genes versus other statins.

Metabolic dysfunction-associated steatotic liver disease-induced changes in the antioxidant system: a review

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a heterogeneous condition characterized by liver steatosis, inflammation, consequent fibrosis, and cirrhosis. Chronic impairment of lipid metabolism is closely related to oxidative stress, leading to cellular lipotoxicity, mitochondrial dysfunction, and endoplasmic reticulum stress. The detrimental effect of oxidative stress is usually accompanied by changes in antioxidant defense mechanisms, with the alterations in antioxidant enzymes expression/activities during MASLD development and progression reported in many clinical and experimental studies. This review will provide a comprehensive overview of the present research on MASLD-induced changes in the catalytic activity and expression of the main antioxidant enzymes (superoxide dismutases, catalase, glutathione peroxidases, glutathione S-transferases, glutathione reductase, NAD(P)H:quinone oxidoreductase) and in the level of non-enzymatic antioxidant glutathione. Furthermore, an overview of the therapeutic effects of vitamin E on antioxidant enzymes during the progression of MASLD will be presented. Generally, at the beginning of MASLD development, the expression/activity of antioxidant enzymes usually increases to protect organisms against the increased production of reactive oxygen species. However, in advanced stage of MASLD, the expression/activity of several antioxidants generally decreases due to damage to hepatic and extrahepatic cells, which further exacerbates the damage. Although the results obtained in patients, in various experimental animal or cell models have been inconsistent, taken together the importance of antioxidant enzymes in MASLD development and progression has been clearly shown.

Diverting hepatic lipid fluxes with lifestyles revision and pharmacological interventions as a strategy to tackle steatotic liver disease (SLD) and hepatocellular carcinoma (HCC)

Steatotic liver disease (SLD) and Hepatocellular Carcinoma (HCC) are characterised by a substantial rewiring of lipid fluxes caused by systemic metabolic unbalances and/or disrupted intracellular metabolic pathways. SLD is a direct consequence of the interaction between genetic predisposition and a chronic positive energy balance affecting whole-body energy homeostasis and the function of metabolically-competent organs. In this review, we discuss how the impairment of the cross-talk between peripheral organs and the liver stalls glucose and lipid metabolism, leading to unbalances in hepatic lipid fluxes that promote hepatic fat accumulation. We also describe how prolonged metabolic stress builds up toxic lipid species in the liver, and how lipotoxicity and metabolic disturbances drive disease progression by promoting a chronic activation of wound healing, leading to fibrosis and HCC. Last, we provide a critical overview of current state of the art (pre-clinical and clinical evidence) regarding mechanisms of action and therapeutic efficacy of candidate SLD treatment options, and their potential to interfere with SLD/HCC pathophysiology by diverting lipids away from the liver therefore improving metabolic health.

Team players in the pathogenesis of metabolic dysfunctions-associated steatotic liver disease: The basis of development of pharmacotherapy

Nutrient metabolism is regulated by several factors. Social determinants of health with or without genetics are the primary regulator of metabolism, and an unhealthy lifestyle affects all modulators and mediators, leading to the adaptation and finally to the exhaustion of cellular functions. Hepatic steatosis is defined by presence of fat in more than 5% of hepatocytes. In hepatocytes, fat is stored as triglycerides in lipid droplet. Hepatic steatosis results from a combination of multiple intracellular processes. In a healthy individual nutrient metabolism is regulated at several steps. It ranges from the selection of nutrients in a grocery store to the last step of consumption of ATP as an energy or as a building block of a cell as structural component. Several hormones, peptides, and genes have been described that participate in nutrient metabolism. Several enzymes participate in each nutrient metabolism as described above from ingestion to generation of ATP. As of now several publications have revealed very intricate regulation of nutrient metabolism, where most of the regulatory factors are tied to each other bidirectionally, making it difficult to comprehend chronological sequence of events. Insulin hormone is the primary regulator of all nutrients' metabolism both in prandial and fasting states. Insulin exerts its effects directly and indirectly on enzymes involved in the three main cellular function processes; metabolic, inflammation and repair, and cell growth and regeneration. Final regulators that control the enzymatic functions through stimulation or suppression of a cell are nuclear receptors in especially farnesoid X receptor and peroxisome proliferator-activated receptor/RXR ligands, adiponectin, leptin, and adiponutrin. Insulin hormone has direct effect on these final modulators. Whereas blood glucose level, serum lipids, incretin hormones, bile acids in conjunction with microbiota are intermediary modulators which are controlled by lifestyle. The purpose of this review is to overview the key players in the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD) that help us understand the disease natural course, risk stratification, role of lifestyle and pharmacotherapy in each individual patient with MASLD to achieve personalized care and target the practice of precision medicine. PubMed and Google Scholar databases were used to identify publication related to metabolism of carbohydrate and fat in states of health and disease states; MASLD, cardiovascular disease and cancer. More than 1000 publications including original research and review papers were reviewed.

Exploration of the Key Genes Involved in Non-alcoholic Fatty Liver Disease and Possible MicroRNA Therapeutic Targets

Background

MicroRNAs (miRNAs) are promising therapeutic agents for non-alcoholic fatty liver disease (NAFLD). This study aimed to identify key genes/proteins involved in NAFLD pathogenesis and progression and to evaluate miRNAs influencing their expression.

Methods

Gene expression profiles from datasets GSE151158, GSE163211, GSE135251, GSE167523, GSE46300, and online databases were analyzed to identify significant NAFLD-related genes. Then, protein-protein interaction networks and module analysis identified hub genes/proteins, which were validated using real-time PCR in oleic acid-treated HepG2 cells. Functional enrichment analysis evaluated signaling pathways and biological processes. Gene-miRNA interaction networks identified miRNAs targeting critical NAFLD genes.

Results

The most critical overexpressed hub genes/proteins included: TNF, VEGFA, TLR4, CYP2E1, ACE, SCD, FASN, SREBF2, and TGFB1 based on PPI network analysis, of which TNF, TLR4, SCD, FASN, SREBF2, and TGFB1 were up-regulated in oleic acid-treated HepG2 cells. Functional enrichment analysis for biological processes highlighted programmed necrotic cell death, lipid metabolic process response to reactive oxygen species, and inflammation. In the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, the highest adjusted P-value signaling pathways encompassed AGE-RAGE in diabetic complications, TNF, and HIF-1 signaling pathways. In gene-miRNA network analysis, miR-16 and miR-124 were highlighted as the miRNAs exerting the most influence on important NAFLD-related genes.

Conclusion

In silico analyses identified NAFLD therapeutic targets and miRNA candidates to guide further experimental investigation.

Recent Progress in Anti-Tumor Nanodrugs Based on Tumor Microenvironment Redox Regulation

The growth state of tumor cells is strictly affected by the specific abnormal redox status of the tumor microenvironment (TME). Moreover, redox reactions at the biological level are also central and fundamental to essential energy metabolism reactions in tumors. Accordingly, anti-tumor nanodrugs targeting the disruption of this abnormal redox homeostasis have become one of the hot spots in the field of nanodrugs research due to the effectiveness of TME modulation and anti-tumor efficiency mediated by redox interference. This review discusses the latest research results of nanodrugs in anti-tumor therapy, which regulate the levels of oxidants or reductants in TME through a variety of therapeutic strategies, ultimately breaking the original "stable" redox state of the TME and promoting tumor cell death. With the gradual deepening of study on the redox state of TME and the vigorous development of nanomaterials, it is expected that more anti-tumor nano drugs based on tumor redox microenvironment regulation will be designed and even applied clinically.

Statins in Chronic Liver Disease: Review of the Literature and Future Role

Chronic liver disease (CLD) is a major contributor to global mortality, morbidity, and healthcare burden. Progress in pharmacotherapeutic for CLD management is lagging given its impact on the global population. While statins are indicated for the management of dyslipidemia and cardiovascular disease, their role in CLD prevention and treatment is emerging. Beyond their lipid-lowering effects, their liver-related mechanisms of action are multifactorial and include anti-inflammatory, antiproliferative, and immune-protective effects. In this review, we highlight what is known about the clinical benefits of statins in viral and nonviral etiologies of CLD and hepatocellular carcinoma (HCC), and explore key mechanisms and pathways targeted by statins. While their benefits may span the spectrum of CLD and potentially HCC treatment, their role in CLD chemoprevention is likely to have the largest impact. As emerging data suggest that genetic variants may impact their benefits, the role of statins in precision hepatology will need to be further explored.

A Systematic Review of Statins for the Treatment of Nonalcoholic Steatohepatitis: Safety, Efficacy, and Mechanism of Action

Nonalcoholic fatty liver disease (NAFLD) is the liver component of a cluster of conditions, while its subtype, nonalcoholic steatohepatitis (NASH), emerges as a potentially progressive liver disorder that harbors the risk of evolving into cirrhosis and culminating in hepatocellular carcinoma (HCC). NASH and cardiovascular disease (CVD) have common risk factors, but compared to liver-related causes, the most common cause of death in NASH patients is CVD. Within the pharmacological armamentarium, statins, celebrated for their lipid-modulating prowess, have now garnered attention for their expansive therapeutic potential in NASH. Evidence from a plethora of studies suggests that statins not only manifest anti-inflammatory and antifibrotic properties but also impart a multifaceted beneficial impact on hepatic health. In this review, we used "statin", "NAFLD", "NASH", and "CVD" as the major keywords and conducted a literature search using the PubMed and Web of Science databases to determine the safety and efficacy of statins in patients and animals with NASH and NAFLD, and the mechanism of statin therapy for NASH. Simultaneously, we reviewed the important role of the intestinal microbiota in statin therapy for NASH, as it is hoped that statins will provide new insights into modulating the harmful inflammatory microbiota in the gut and reducing systemic inflammation in NASH patients.

Inflammation drives pathogenesis of early intestinal failure-associated liver disease

Patients with intestinal failure who receive long-term parenteral nutrition (PN) often develop intestinal failure-associated liver disease (IFALD). Although there are identified risk factors, the early pathogenesis is poorly understood and treatment options are limited. Here, we perform a transcriptomic analysis of liver tissue in a large animal IFALD model to generate mechanistic insights and identify therapeutic targets. Preterm Yorkshire piglets were provided PN or bottle-fed with sow-milk replacer for 14 days. Compared to bottle-fed controls, piglets receiving PN developed biochemical cholestasis by day of life 15 (total bilirubin 0.2 vs. 2.9 mg/dL, P = 0.01). RNA-Seq of liver tissue was performed. Ingenuity Pathway Analysis identified 747 differentially expressed genes (343 upregulated and 404 downregulated) with an adjusted P < 0.05 and a fold-change of > |1|. Enriched canonical pathways were identified, demonstrating broad activation of inflammatory pathways and inhibition of cell cycle progression. Potential therapeutics including infliximab, glucocorticoids, statins, and obeticholic acid were identified as predicted upstream master regulators that may reverse the PN-induced gene dysregulation. The early driver of IFALD in neonates may be inflammation with an immature liver; identified therapeutics that target the inflammatory response in the liver should be investigated as potential treatments.

Organelle stress and alterations in interorganelle crosstalk during liver fibrosis

The synchronous functioning and quality control of organelles ensure cell survival and function and are essential for maintaining homeostasis. Prolonged exposure to stressors (viruses, bacteria, parasitic infections, alcohol, drugs) or genetic mutations often disrupt the functional integrity of organelles which plays a critical role in the initiation and progression of several diseases including chronic liver diseases. One of the most important pathologic consequences of chronic liver diseases is liver fibrosis, characterized by tissue scarring due to the progressive accumulation of extracellular matrix components. Left untreated, fibrosis may advance to life-threatening complications such as cirrhosis, hepatic decompensation, and HCC, which collectively accounts for ∼1 million deaths per year worldwide. Owing to the lack of treatment options that can regress or reverse cirrhosis, liver transplantation is currently the only available treatment for end-stage liver disease. However, the limited supply of usable donor organs, adverse effects of lifelong immunosuppressive regimes, and financial considerations pose major challenges and limit its application. Hence, effective therapeutic strategies are urgently needed. An improved understanding of the organelle-level regulation of fibrosis can help devise effective antifibrotic therapies focused on reducing organelle stress, limiting organelle damage, improving interorganelle crosstalk, and restoring organelle homeostasis; and could be a potential clinical option to avoid transplantation. This review provides a timely update on the recent findings and mechanisms covering organelle-specific dysfunctions in liver fibrosis, highlights how correction of organelle functions opens new treatment avenues and discusses the potential challenges to clinical application.

Statin therapy: a potential adjuvant to immunotherapies in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide and accounts for more than 90% of primary liver cancer. The advent of immune checkpoint inhibitor (ICI)-related therapies combined with angiogenesis inhibition has revolutionized the treatment of HCC in late-stage and unresectable HCC, as ICIs alone were disappointing in treating HCC. In addition to the altered immune microenvironment, abnormal lipid metabolism in the liver has been extensively characterized in various types of HCC. Stains are known for their cholesterol-lowering properties and their long history of treating hypercholesterolemia and reducing cardiovascular disease risk. Apart from ICI and other conventional therapies, statins are frequently used by advanced HCC patients with dyslipidemia, which is often marked by the abnormal accumulation of cholesterol and fatty acids in the liver. Supported by a body of preclinical and clinical studies, statins may unexpectedly enhance the efficacy of ICI therapy in HCC patients through the regulation of inflammatory responses and the immune microenvironment. This review discusses the abnormal changes in lipid metabolism in HCC, summarizes the clinical evidence and benefits of stain use in HCC, and prospects the possible mechanistic actions of statins in transforming the immune microenvironment in HCC when combined with immunotherapies. Consequently, the use of statin therapy may emerge as a novel and valuable adjuvant for immunotherapies in HCC.

Gowda SG, Chen Y, Hui SP. Crosstalk between Lipids and Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD), a complex liver disorder that can result in non-alcoholic steatohepatitis, cirrhosis, and liver cancer, is the accumulation of fat in the liver seen in people due to metabolic dysfunction. The pathophysiology of NAFLD is influenced by several variables, such as metabolic dysregulation, oxidative stress, inflammation, and genetic susceptibility. This illness seriously threatens global health because of its link to obesity, insulin resistance, type 2 diabetes, and other metabolic disorders. In recent years, lipid–NAFLD crosstalk has drawn a lot of interest. Through numerous methods, lipids have been connected to the onset and advancement of the illness. The connection between lipids and NAFLD is the main topic of the current review, along with the various therapeutic targets and currently available drugs. The importance of hepatic lipid metabolism in the progression of NAFLD is summarized with the latest results in the field.

Atorvastatin rescues hyperhomocysteinemia-induced cognitive deficits and neuroinflammatory gene changes

BACKGROUND

Epidemiological data suggests statins could reduce the risk of dementia, and more specifically, Alzheimer's disease (AD). Pre-clinical data suggests statins reduce the risk of dementia through their pleiotropic effects rather than their cholesterol lowering effects. While AD is a leading cause of dementia, it is frequently found co-morbidly with cerebral small vessel disease and other vascular contributions to cognitive impairment and dementia (VCID), which are another leading cause of dementia. In this study, we determined if atorvastatin ameliorated hyperhomocysteinemia (HHcy)-induced VCID.

METHODS

Wild-type (C57Bl6/J) mice were placed on a diet to induce HHcy or a control diet each with or without atorvastatin for 14 weeks. Mice underwent novel object recognition testing before tissue collection. Plasma total cholesterol and total homocysteine as well as related metabolites were measured. Using qPCR and NanoString technology, we profiled glial cell-associated gene expression changes. Finally, microglial morphology, astrocyte end feet, and microhemorrhages were analyzed using histological methods.

RESULTS

Atorvastatin treatment of HHcy in mice led to no changes in total cholesterol but decreases in total homocysteine in plasma. While HHcy decreased expression of many glial genes, atorvastatin rescued these gene changes, which mostly occurred in oligodendrocytes and microglia. Microglia in HHcy mice with atorvastatin were trending towards fewer processes compared to control with atorvastatin, but there were no atorvastatin effects on astrocyte end feet. While atorvastatin treatment was trending towards increasing the area of microhemorrhages in HHcy mice in the frontal cortex, it only slightly (non-significantly) reduced the number of microhemorrhages. Finally, atorvastatin treatment in HHcy mice led to improved cognition on the novel object recognition task.

CONCLUSIONS

These data suggest that atorvastatin rescued cognitive changes induced by HHcy most likely through lowering plasma total homocysteine and rescuing gene expression changes rather than impacts on vascular integrity or microglial changes.

Statins on nonalcoholic fatty liver disease: A systematic review and meta-analysis of 14 RCTs

BACKGROUND

The prevalence of nonalcoholic fatty liver disease (NAFLD) is rising rapidly in the world. Our aim is to investigate the efficacy and safety of statins in the treatment of NAFLD.

METHODS

This study was conducted by searching The National Library of Medicine, Cochrane Library, China National Knowledge Infrastructure, Web of Science, and Wanfang Data Knowledge Service Platform databases. Literature data are expressed as mean difference (MD) and 95% confidence intervals (CIs) or relative risk and 95% CI. For I2 > 50% trials, random effect model is used for statistical analysis, otherwise fixed effect model is used.

RESULTS

Fourteen studies are selected for this meta-analysis, which includes totally 534 patients in the treatment group and 527 patients in the control group. As a result, 5 studies show that the total effective rate of the treatment group is 17% higher than that of the control group (Z = 2.11, relative risk = 1.17, 95% CI: [1.01-1.35]). Twelve studies show that alanine aminotransferase levels of the experimental group are lower than that of the control group (Z = 2.63, P = .009, MD = -5.53, 95% CI: [-9.64 to -1.41]). Eleven studies show that aspartate transaminase levels of the experimental group are lower than that of the control group (Z = 2.01, P = .04, MD = -3.43, 95% CI: [-6.77 to -0.08]). Six studies show that alkaline phosphatase levels of the experimental group are lower than that of the control group (Z = 0.79, P = .43, MD = -3.46, 95% CI: [-12.08 to 5.16]). Eight studies show that gamma-glutamyl transpeptidase levels of the experimental group are lower than that of the control group (Z = 2.04, P = .04, MD = -4.05, 95% CI: [-7.96 to -0.15]). Thirteen studies show that triglyceride levels of the experimental group are lower than that of the control group (Z = 4.15, P < .0001, MD = -0.94, 95% CI: [-1.39 to -0.50]). Eleven studies show that the total cholesterol levels of the experimental group are lower than that of the control group (Z = 5.42, P < .00001, MD = -1.51, 95% CI: [-2.05 to -0.96]). Seven studies show that low-density lipoprotein-cholesterol levels of the experimental group are lower than that of the control group (Z = 5.00, P < .00001, MD = -0.85, 95% CI: [-1.18 to -0.52]).

CONCLUSION

Statins can significantly reduce liver biochemical indicators in patients with NAFLD.

Serum metabolomic signatures of fatty acid oxidation defects differentiate host-response subphenotypes of acute respiratory distress syndrome

BACKGROUND

Fatty acid oxidation (FAO) defects have been implicated in experimental models of acute lung injury and associated with poor outcomes in critical illness. In this study, we examined acylcarnitine profiles and 3-methylhistidine as markers of FAO defects and skeletal muscle catabolism, respectively, in patients with acute respiratory failure. We determined whether these metabolites were associated with host-response ARDS subphenotypes, inflammatory biomarkers, and clinical outcomes in acute respiratory failure.

METHODS

In a nested case-control cohort study, we performed targeted analysis of serum metabolites of patients intubated for airway protection (airway controls), Class 1 (hypoinflammatory), and Class 2 (hyperinflammatory) ARDS patients (N = 50 per group) during early initiation of mechanical ventilation. Relative amounts were quantified by liquid chromatography high resolution mass spectrometry using isotope-labeled standards and analyzed with plasma biomarkers and clinical data.

RESULTS

Of the acylcarnitines analyzed, octanoylcarnitine levels were twofold increased in Class 2 ARDS relative to Class 1 ARDS or airway controls (P = 0.0004 and < 0.0001, respectively) and was positively associated with Class 2 by quantile g-computation analysis (P = 0.004). In addition, acetylcarnitine and 3-methylhistidine were increased in Class 2 relative to Class 1 and positively correlated with inflammatory biomarkers. In all patients within the study with acute respiratory failure, increased 3-methylhistidine was observed in non-survivors at 30 days (P = 0.0018), while octanoylcarnitine was increased in patients requiring vasopressor support but not in non-survivors (P = 0.0001 and P = 0.28, respectively).

CONCLUSIONS

This study demonstrates that increased levels of acetylcarnitine, octanoylcarnitine, and 3-methylhistidine distinguish Class 2 from Class 1 ARDS patients and airway controls. Octanoylcarnitine and 3-methylhistidine were associated with poor outcomes in patients with acute respiratory failure across the cohort independent of etiology or host-response subphenotype. These findings suggest a role for serum metabolites as biomarkers in ARDS and poor outcomes in critically ill patients early in the clinical course.

Atorvastatin Attenuates Diet-Induced Non-Alcoholic Steatohepatitis in APOE*3-Leiden Mice by Reducing Hepatic Inflammation

Patients with metabolic syndrome are often prescribed statins to prevent the development of cardiovascular disease. Conversely, data on their effects on non-alcoholic steatohepatitis (NASH) are lacking. We evaluated these effects by feeding APOE*3-Leiden mice a Western-type diet (WTD) with or without atorvastatin to induce NASH and hepatic fibrosis. Besides the well-known plasma cholesterol lowering (-30%) and anti-atherogenic effects (severe lesion size -48%), atorvastatin significantly reduced hepatic steatosis (-22%), the number of aggregated inflammatory cells in the liver (-80%) and hepatic fibrosis (-92%) compared to WTD-fed mice. Furthermore, atorvastatin-treated mice showed less immunohistochemically stained areas of inflammation markers. Atorvastatin prevented accumulation of free cholesterol in the form of cholesterol crystals (-78%). Cholesterol crystals are potent inducers of the NLRP3 inflammasome pathway and atorvastatin prevented its activation, which resulted in reduced expression of the pro-inflammatory cytokines interleukin (IL)-1β (-61%) and IL-18 (-26%). Transcriptome analysis confirmed strong reducing effects of atorvastatin on inflammatory mediators, including NLRP3, NFκB and TLR4. The present study demonstrates that atorvastatin reduces hepatic steatosis, inflammation and fibrosis and prevents cholesterol crystal formation, thereby precluding NLRP3 inflammasome activation. This may render atorvastatin treatment as an attractive approach to reduce NAFLD and prevent progression into NASH in dyslipidemic patients.

Effects of metformin and simvastatin treatment on ultrastructural features of liver macrophages in HFD mice

Type 2 diabetes is a major health burden to the society. Macrophages and liver inflammation emerged as important factors in its development. We investigated ultrastructural changes in the liver, with a special emphasis on macrophages in high fat diet (HFD) fed C57BL/6 J mice treated with metformin or simvastatin, two drugs that are used frequently in diabetes. Both metformin and simvastatin reduced the liver damage in HFD fed animals, manifested as the prevention of nonalcoholic steatohepatitis development and reduced activation and number of macrophages in the liver, as well as the percentage of these cells with lipid droplets in the cytoplasm compared to untreated HFD animals. In contrast with untreated HFD-fed animals, lipid droplets were not observed in lysosomes of macrophages in HFD animals treated with metformin and simvastatin. These findings provide new insight into the effects of metformin and simvastatin on the liver in this experimental model of type 2 diabetes and provide further rationale for implementation of statins in the therapeutic regimens in this disease.

The interplay between nonalcoholic fatty liver disease and atherosclerotic cardiovascular disease

Therapeutic approaches that lower circulating low-density lipoprotein (LDL)-cholesterol significantly reduced the burden of cardiovascular disease over the last decades. However, the persistent rise in the obesity epidemic is beginning to reverse this decline. Alongside obesity, the incidence of nonalcoholic fatty liver disease (NAFLD) has substantially increased in the last three decades. Currently, approximately one third of world population is affected by NAFLD. Notably, the presence of NAFLD and particularly its more severe form, nonalcoholic steatohepatitis (NASH), serves as an independent risk factor for atherosclerotic cardiovascular disease (ASCVD), thus, raising interest in the relationship between these two diseases. Importantly, ASCVD is the major cause of death in patients with NASH independent of traditional risk factors. Nevertheless, the pathophysiology linking NAFLD/NASH with ASCVD remains poorly understood. While dyslipidemia is a common risk factor underlying both diseases, therapies that lower circulating LDL-cholesterol are largely ineffective against NASH. While there are no approved pharmacological therapies for NASH, some of the most advanced drug candidates exacerbate atherogenic dyslipidemia, raising concerns regarding their adverse cardiovascular consequences. In this review, we address current gaps in our understanding of the mechanisms linking NAFLD/NASH and ASCVD, explore strategies to simultaneously model these diseases, evaluate emerging biomarkers that may be useful to diagnose the presence of both diseases, and discuss investigational approaches and ongoing clinical trials that potentially target both diseases.

Statins for the Treatment of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis: A Systematic Review and Meta-Analysis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has become more common as a result of changes in dietary structure and lifestyle. It is now the most common chronic liver disease both in China and in the rest of the world (NAFLD is also of concern in European and American countries).

STUDY QUESTION

NAFLD and nonalcoholic steatohepatitis (NASH) are different stages of fatty liver disease. There is currently a lack of consensus on the use of statin therapy. We conducted a meta-analysis to evaluate the efficacy of statins in the treatment of NAFLD and NASH.

DATA SOURCES

PubMed, MEDLINE, and other literature databases, including the Cochrane Library, were searched.

STUDY DESIGN

The primary inclusion criteria for studies included the use of different statins for the treatment of NAFLD and NASH. Two reviewers identified documents and extracted data based on predetermined inclusion and exclusion criteria. To examine heterogeneity and publication bias, all analyses were undertaken using the complete meta-analysis Review Manager 5.3 software.

RESULTS

The meta-analysis includes 4 randomized controlled studies involving 169 participants with NAFLD and NASH. In comparison with the control group, statins dramatically lowered serum levels of aspartate transaminase, alanine aminotransferase (ALT), triglycerides, and cholesterol.

CONCLUSIONS

The use of statins in the treatment of NAFLD and NASH has shown significant histological and biochemical benefits, especially in patients with hyperlipidemia. To assess the effects of statins on NAFLD and NASH, more large research and randomized placebo-controlled trials are needed.

Effects of SLCO1B1 Genetic Variant on Metabolite Profile in Participants on Simvastatin Treatment

Organic-anion-transporting polypeptide 1B1 (OATP1B1), encoded by the solute carrier organic anion transporter family member 1B1 gene (SLCO1B1), is highly expressed in the liver and transports several endogenous metabolites into the liver, including statins. Previous studies have not investigated the association of SLCO1B1 rs4149056 variant with the risk of type 2 diabetes (T2D) or determined the metabolite signature of the C allele of SLCO1B1 rs4149056 (SLCO1B1 rs4149056-C allele) in a large randomly selected population. SLCO1B1 rs4149056-C inhibits OATP1B1 transporter and is associated with increased levels of blood simvastatin concentrations. Our study is to first to show that SLCO1B1 rs4149056 variant is not significantly associated with the risk of T2D, suggesting that simvastatin has a direct effect on the risk of T2D. Additionally, we investigated the effects of SLCO1B1 rs4149056-C on plasma metabolite concentrations in 1373 participants on simvastatin treatment and in 1368 age- and body-mass index (BMI)-matched participants without any statin treatment. We found 31 novel metabolites significantly associated with SLCO1B1 rs4149056-C in the participants on simvastatin treatment and in the participants without statin treatment. Simvastatin decreased concentrations of dicarboxylic acids, such as docosadioate and dodecanedioate, that may increase beta- and peroxisomal oxidation and increased the turnover of cholesterol into bile acids, resulting in a decrease in steroidogenesis due to limited availability of cholesterol for steroid synthesis. Our findings suggest that simvastatin exerts its effects on the lowering of low-density lipoprotein (LDL) cholesterol concentrations through several distinct pathways in the carriers of SLCO1B1 rs4149056-C, including dicarboxylic acids, bile acids, steroids, and glycerophospholipids.

Association of Statin Adherence With the Development of Nonalcoholic Fatty Liver Disease: A Nested Case-Control Study Using a Japanese Claims Database

BACKGROUND

Statins are expected to have beneficial effects on nonalcoholic fatty liver disease (NAFLD); however, evidence remains insufficient.

OBJECTIVE

In this study, we aim to investigate the association between statin adherence and NAFLD development.

METHODS

We conducted a nested case-control study of statin users using the Japan Medical Data Center administrative claims database (January 2005 to January 2020). Individuals who developed NAFLD were designated as cases. For each case, we randomly selected a maximum of 10 controls using risk set sampling. Good adherence was defined as the proportion of days covered (PDC) of ≥0.80. Higher intensity was defined as the median or higher of a cumulative defined daily dose (cDDD) per day covered by statin prescription. Conditional logistic regression analysis was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

In this study, 253 383 patients with the first statin prescription were identified. Of them, 7080 were selected and matched to 70 734 controls. The medians of PDC and intensity were 0.88 (interquartile range [IQR], 0.61-0.96) and 0.32 (IQR, 0.25-0.50) cDDD/day, respectively. Good adherence was significantly associated with a reduced risk of NAFLD development (adjusted OR, 0.82; 95% CI, 0.78-0.86). Higher intensity was not significantly associated with a reduced risk of NAFLD development (adjusted OR, 1.02; 95% CI, 0.97-1.08).

CONCLUSION AND RELEVANCE

Good adherence to statins is associated with a reduced risk of NAFLD development, regardless of the statin intensity. Appropriate statin therapy could reduce the risk of NAFLD development.

Regulation of Hepatic Lipid and Glucose Metabolism by INSP3R1

With the rising epidemics of obesity and nonalcoholic fatty liver disease (NAFLD) and its downstream consequences including steatohepatitis, cirrhosis, and type 2 diabetes in the U.S. and worldwide, new therapeutic approaches are urgently needed to treat these devastating conditions. Glucagon, known for a century to be a glucose-raising hormone and clearly demonstrated to contribute to fasting and postprandial hyperglycemia in both type 1 and type 2 diabetes, represents an unlikely target to improve health in those with metabolic syndrome. However, recent work from our group and others' identifies an unexpected role for glucagon as a potential means of treating NAFLD, improving insulin sensitivity, and improving the lipid profile. We propose a unifying, calcium-dependent mechanism for glucagon's effects both to stimulate hepatic gluconeogenesis and to enhance hepatic mitochondrial oxidation: signaling through the inositol 1,4,5-trisphosphate receptor type 1 (INSP3R1), glucagon activates phospholipase C (PKC)/protein kinase A (PKA) signaling to enhance adipose triglyceride lipase (ATGL)-dependent intrahepatic lipolysis and, in turn, increase cytosolic gluconeogenesis by allosteric activation of pyruvate carboxylase. Simultaneously in the mitochondria, calcium transferred through mitochondria-associated membranes activates several dehydrogenases in the tricarboxylic acid cycle, correlated with an increase in mitochondrial energy expenditure and reduction in ectopic lipid. This model suggests that short-term, cyclic treatment with glucagon or other INSP3R1 antagonists could hold promise as a means to reset lipid homeostasis in patients with NAFLD.

Targeted therapeutics and novel signaling pathways in non-alcohol-associated fatty liver/steatohepatitis (NAFL/NASH)

Non-alcohol-associated fatty liver/steatohepatitis (NAFL/NASH) has become the leading cause of liver disease worldwide. NASH, an advanced form of NAFL, can be progressive and more susceptible to developing cirrhosis and hepatocellular carcinoma. Currently, lifestyle interventions are the most essential and effective strategies for preventing and controlling NAFL without the development of fibrosis. While there are still limited appropriate drugs specifically to treat NAFL/NASH, growing progress is being seen in elucidating the pathogenesis and identifying therapeutic targets. In this review, we discussed recent developments in etiology and prospective therapeutic targets, as well as pharmacological candidates in pre/clinical trials and patents, with a focus on diabetes, hepatic lipid metabolism, inflammation, and fibrosis. Importantly, growing evidence elucidates that the disruption of the gut-liver axis and microbe-derived metabolites drive the pathogenesis of NAFL/NASH. Extracellular vesicles (EVs) act as a signaling mediator, resulting in lipid accumulation, macrophage and hepatic stellate cell activation, further promoting inflammation and liver fibrosis progression during the development of NAFL/NASH. Targeting gut microbiota or EVs may serve as new strategies for the treatment of NAFL/NASH. Finally, other mechanisms, such as cell therapy and genetic approaches, also have enormous therapeutic potential. Incorporating drugs with different mechanisms and personalized medicine may improve the efficacy to better benefit patients with NAFL/NASH.

Supplementation of Lycium barbarum Polysaccharide Combined with Aerobic Exercise Ameliorates High-Fat-Induced Nonalcoholic Steatohepatitis via AMPK/PPARα/PGC-1α Pathway

Nonalcoholic steatohepatitis (NASH) is a subtype of nonalcoholic fatty liver disease (NAFLD). Either Lycium barbarum polysaccharide (LBP) or aerobic exercise (AE) has been reported to be beneficial to hepatic lipid metabolism. However, whether the combination of LBP with AE improves lipid accumulation of NASH remains unknown. Our study investigated the influence of 10 weeks of treatment of LBP, AE, and the combination (LBP plus AE) on high-fat-induced NASH in Sprague-Dawley rats. The results showed that LBP or AE reduced the severity of the NASH. LBP plus AE treatment more effectively ameliorated liver damage and lowered levels of serum lipid and inflammation. In addition, the combination can also regulate genes involved in hepatic fatty acid synthesis and oxidation. LBP plus AE activated AMPK, thereby increasing the expression of PPARα which controls hepatic fatty acid oxidation and its coactivator PGC-1α. Our study demonstrated the improvement of LBP plus AE on NASH via enhancing fatty acid oxidation (FAO) which was dependent on AMPK/PPARα/PGC-1α pathway.

Association between organochlorine pesticides and nonalcoholic fatty liver disease in the National Health and Nutrition Examination Survey 2003-2004

While endocrine disruptors are emerging as a cause of nonalcoholic fatty liver disease (NAFLD), little is known about the link between NAFLD and organochlorine pesticides (OCPs), one of the endocrine disruptors. We retrospectively analyzed the U.S. National Health and Nutrition Examination Survey 2003-2004 and compared the baseline demographics in individuals according to the presence of NAFLD (fatty liver index [FLI] ≥ 60). Logistic regression analysis was performed to determine whether OCP concentration affected NAFLD prevalence and subgroup analyses regarding NAFLD-related variables and advanced hepatic fibrosis (FIB-4 ≥ 2.67) were performed. Of the 1515 individuals, 579 (38.2%) had NAFLD. Oxychlordane showed concentration-dependent risk for NAFLD (OR 3.471 in fourth quartile [Q4]; 95% CI 1.865-6.458; P = 0.007). p,p'-DDE and trans-nonachlor showed similar trends without statistical significance. Conversely, mirex showed the lowest risk for NAFLD in the highest concentration quartile (OR 0.29 in Q4; 95% CI 0.175-0.483; P < 0.001). Oxychlordane showed the most pronounced association with the levels of each component of FLI and liver enzymes. None of the OCPs were significantly associated with advanced fibrosis. In conclusion, among OCPs, exposure to oxychlordane showed the most prominent impact associated with NAFLD.

PPAR Alpha as a Metabolic Modulator of the Liver: Role in the Pathogenesis of Nonalcoholic Steatohepatitis (NASH)

Simple Summary

In the context of liver disease, one of the more growing public health problems is the transition from simple steatosis to non-alcoholic steatohepatitis. Profound metabolic dysregulations linked to inflammation and hepatic injury are features of non-alcoholic steatohepatitis. Since the peroxisomal-proliferator-activated receptor alpha has long been considered one of the key transcriptional factors in hepatic metabolism, its role in the pathogenesis of non-alcoholic steatohepatitis is discussed in this review.

Abstract

The strong relationship between metabolic alterations and non-alcoholic steatohepatitis (NASH) suggests a pathogenic interplay. However, many aspects have not yet been fully clarified. Nowadays, NASH is becoming the main cause of liver-associated morbidity and mortality. Therefore, an effort to understand the mechanisms underlying the pathogenesis of NASH is critical. Among the nuclear receptor transcription factors, peroxisome-proliferator-activated receptor alpha (PPARα) is highly expressed in the liver, where it works as a pivotal transcriptional regulator of the intermediary metabolism. In this context, PPARα’s function in regulating the lipid metabolism is essential for proper liver functioning. Here, we review metabolic liver genes under the control of PPARα and discuss how this aspect can impact the inflammatory condition and pathogenesis of NASH.

PharmOmics: A species- and tissue-specific drug signature database and gene-network-based drug repositioning tool

Drug development has been hampered by a high failure rate in clinical trials due to our incomplete understanding of drug functions across organs and species. Therefore, elucidating species- and tissue-specific drug functions can provide insights into therapeutic efficacy, potential adverse effects, and interspecies differences necessary for effective translational medicine. Here, we present PharmOmics, a drug knowledgebase and analytical tool that is hosted on an interactive web server. Using tissue- and species-specific transcriptome data from human, mouse, and rat curated from different databases, we implemented a gene-network-based approach for drug repositioning. We demonstrate the potential of PharmOmics to retrieve known therapeutic drugs and identify drugs with tissue toxicity using in silico performance assessment. We further validated predicted drugs for nonalcoholic fatty liver disease in mice. By combining tissue- and species-specific in vivo drug signatures with gene networks, PharmOmics serves as a complementary tool to support drug characterization and network-based medicine.

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Development of PharmOmics, a platform for drug repositioning and toxicity prediction

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Contains >18000 species/tissue-specific gene signatures for 941 drugs and chemicals

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Benchmarked and validated network-based drug repositioning and toxicity prediction

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PharmOmics is freely accessible via an online web server to facilitate user access

Bifidobacterium animalis subsp. lactis A6 Enhances Fatty Acid β-Oxidation of Adipose Tissue to Ameliorate the Development of Obesity in Mice

Fatty acid β-oxidation (FAO) is confirmed to be impaired in obesity, especially in adipose tissues. We previously proved that Bifidobacterium animalis subsp. lactis A6 (BAA6) had protective effects against diet-induced obesity. However, whether BAA6 enhances FAO to ameliorate the development of obesity has not been explored. After being fed with high-fat diet (HFD) for 9 weeks, male C57BL/6J mice were fed HFD or BAA6 for 8 weeks. In vitro study was carried out using 3T3-L1 adipocytes to determine the effect of BAA6 culture supernatant (BAA6-CM). Here, we showed that administration of BAA6 to mice fed with HFD decreased body weight gain (by 5.03 g) and significantly up-regulated FAO in epididymal adipose tissues. In parallel, FAO in 3T3-L1 cells was increased after BAA6-CM treatment. Acetate was identified as a constituent of BAA6-CM that showed a similar effect to BAA6-CM. Furthermore, acetate treatment activated the GPR43-PPARα signaling, thereby promoting FAO in 3T3-L1 cells. The levels of acetate were also elevated in serum and feces (by 1.92- and 2.27-fold) of HFD-fed mice following BAA6 administration. The expression levels of GPR43 and PPARα were increased by 55.45% and 69.84% after BAA6 supplement in the epididymal fat of mice. Together, these data reveal that BAA6 promotes FAO of adipose tissues through the GPR43-PPARα signaling, mainly by increasing acetate levels, leading to alleviating the development of obesity.

Is there a role of lipid-lowering therapies in the management of fatty liver disease?

Atherogenic dyslipidemia is characterized by increased triglyceride-rich lipoproteins and low high-density lipoprotein cholesterol concentrations. It is highly prevalent in non-alcoholic fatty liver disease (NAFLD) and contributes to the increased cardiovascular risk associated with this condition. Alongside insulin resistance it plays an important pathogenetic role in NAFLD/non-alcoholic steatohepatitis (NASH) development and progression. It has been shown that cholesterol-lowering reduces cardiovascular risk more in NAFLD vs non-NAFLD high-risk individuals. This evidence highlights the importance of effective lipid modulation in NAFLD. In this narrative review the effects of the most commonly used lipid-lowering therapies on liver outcomes alongside their therapeutic implications in NAFLD/NASH are critically discussed. Preclinical and clinical evidence suggests that statins reduce hepatic steatosis, inflammation and fibrosis in patients with NAFLD/NASH. Most data are derived from observational and small prospective clinical studies using changes in liver enzyme activities, steatosis/fibrosis scores, and imaging evidence of steatosis as surrogates. Also, relevant histologic benefits were noted in small biopsy studies. Atorvastatin and rosuvastatin showed greater benefits, whereas data for other statins are scarce and sometimes conflicting. Similar studies to those of statins showed efficacy of ezetimibe against hepatic steatosis. However, no significant anti-inflammatory and anti-fibrotic actions of ezetimibe have been shown. Preclinical studies showed that fibrates through peroxisome proliferator-activated receptor (PPAR)α activation may have a role in NAFLD prevention and management. Nevertheless, no relevant benefits have been noted in human studies. Species-related differences in PPARα expression and its activation responsiveness may help explain this discrepancy. Omega-3 fatty acids reduced hepatic steatosis in numerous heterogeneous studies, but their benefits on hepatic inflammation and fibrosis have not been established. Promising preliminary data for the highly purified eicosapentaenoic acid require further confirmation. Observational studies suggest that proprotein convertase subtilisin/kexin9 inhibitors may also have a role in the management of NAFLD, though this needs to be established by future prospective studies.

Statins in Non-alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the primary cause of chronic liver disease. The range is extensive, including hepatocellular carcinoma, cirrhosis, fibrosis, fatty liver, and non-alcoholic steatohepatitis (NASH). NASH is a condition related to obesity, overweight, metabolic syndrome, diabetes, and dyslipidemia. It is a dynamic condition that can regress to isolated steatosis or progress to fibrosis and cirrhosis. Statins exert anti-inflammatory, proapoptotic, and antifibrotic effects. It has been proposed that these drugs could have a relevant role in NASH. In this review, we provide an overview of current evidence, from mechanisms of statins involved in the modulation of NASH to human trials about the use of statins to treat or attenuate NASH.

Impact of statin use on the risk and prognosis of hepatocellular carcinoma: a meta-analysis

BACKGROUND

Previous studies have demonstrated that statin use might be associated with a reduced risk of hepatocellular carcinoma (HCC). However, the value of statin on the prognosis still needs to be evaluated. Based on the above considerations, we conducted a meta-analysis regarding the value of statin on the prevention and prognosis of HCC.

METHODS

Articles regarding the impact of statin use on the risk, prognosis of HCC and published before October 2020 were searched in the five databases. We computed odds ratio (OR)/relative risk (RR) or hazard ratio (HR) and 95% confidence intervals (CIs) regarding the association between statin use and the risk or prognosis of HCC by using STATA 12.0 software.

RESULTS

Twenty-six studies (including 1772 463 participants) detected the association between statin use and risk of HCC. Additionally, seven studies (including 8925 statin users and 76 487 no-statin users) explored the association between statin use and mortality of HCC. The meta-analysis showed that statin use was associated with lower risk and all-cause mortality of HCC with random effects models (risk: OR/RR = 0.57, 95% CI 0.49-0.65, I2 = 86.0%, P < 0.0001; all-cause mortality: HR = 0.80, 95% CI 0.68-0.94, I2 = 77.6%, P < 0.0001). However, statin use was not associated with cancer-specific mortality of HCC with a random effects model (HR = 0.80, 95% CI 0.62-1.03, I2 = 73.9%, P = 0.002).

CONCLUSION

In conclusion, our results have demonstrated the salutary effect of statin on the prevention and prognosis of HCC.

Simvastatin affects the PPARα signaling pathway and causes oxidative stress and embryonic development interference in Mugilogobius abei

Simvastatin (SV) is a common hypolipidemic drug in clinical medicine that can reduce endogenous cholesterol biosynthesis by inhibiting hydroxyl-methyl-glutaryl coenzyme A reductase. SV took a large market share in the lipid-lowering drugs and it is frequently detected in various water bodies due to its increasing consumption in past years. In the present investigation, we selected a native fish species in the Pearl River Basin in China, Mugilogobius abei (M. abei), to study the effects of SV on non-target aquatic organisms. Results showed that a significant decrease in the volume of adipocytes under SV exposure were observed on oil red O section, and the expression of HMG-CoAR decreased significantly. The mRNA and protein expression of PPARα were significantly up-regulated, the expressions of other genes related to lipid metabolism were up-regulated to varying degrees as well. There was a positive correlation between the concentrations of SV and the protein expressions of plasma phospholipid transfer protein (PLTP) and cholesterolester transfer protein (CETP). In addition, the frozen sections showed that SV led to ROS accumulation in liver in a time and concentration dependent manner. The mRNA and protein expressions of Nrf2 were significantly up-regulated after 24 hours of SV exposure. Some biomarkers associated with antioxidant such as Trx2, TrxR and MDA content were positively correlated with the exposure concentration and time, while the content of GSH decreased sharply. It is noteworthy that the environmentally relevant concentration (0.5 μg/L) of SV exposure caused delayed embryonic development and deformations, decreased hatching rates. We conclude that SV promotes fat metabolism, gives rise to oxidative stress and has significant toxicity on embryo development in M. abei.

Peroxisomal footprint in the pathogenesis of nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a form of fatty liver disease where benign hepatic steatosis leads to chronic inflammation in the steatotic liver of a patient without any history of alcohol abuse. Mechanisms underlying the progression of hepatic steatosis to NASH have long been investigated. This review outlines the potential role of peroxisomal dysfunctions in exacerbating the disease in NASH. Loss of peroxisomes as well as impaired peroxisomal functions have been demonstrated to occur in inflammatory conditions including NASH. Because peroxisomes and mitochondria co-operatively perform many metabolic functions including O₂ and lipid metabolisms, a compromised peroxisomal biogenesis and function can potentially contribute to defective lipid and reactive oxygen species metabolism which in turn can lead the progression of disease in NASH. Impaired peroxisomal biogenesis and function may be due to the decreased expression of peroxisomal proliferator-activated receptor-α (PPAR-α), the major transcription factor of peroxisomal biogenesis. Recent studies indicate that the reduced expression of PPAR-α in NASH is correlated with the activation of the toll-like receptor-4 pathway (TLR-4). Further investigations are required to establish the mechanistic connection between the TLR-4 pathway and PPAR-α-dependent impaired biogenesis/function of peroxisomes in NASH.

PPARs as Metabolic Sensors and Therapeutic Targets in Liver Diseases

Carbohydrates and lipids are two components of the diet that provide the necessary energy to carry out various physiological processes to help maintain homeostasis in the body. However, when the metabolism of both biomolecules is altered, development of various liver diseases takes place; such as metabolic-associated fatty liver diseases (MAFLD), hepatitis B and C virus infections, alcoholic liver disease (ALD), and in more severe cases, hepatocelular carcinoma (HCC). On the other hand, PPARs are a family of ligand-dependent transcription factors with an important role in the regulation of metabolic processes to hepatic level as well as in other organs. After interaction with specific ligands, PPARs are translocated to the nucleus, undergoing structural changes to regulate gene transcription involved in lipid metabolism, adipogenesis, inflammation and metabolic homeostasis. This review aims to provide updated data about PPARs’ critical role in liver metabolic regulation, and their involvement triggering the genesis of several liver diseases. Information is provided about their molecular characteristics, cell signal pathways, and the main pharmacological therapies that modulate their function, currently engaged in the clinic scenario, or in pharmacological development.

Atorvastatin Modulates Bile Acid Homeostasis in Mice with Diet-Induced Nonalcoholic Steatohepatitis

Bile acids (BA) play a significant role in the pathophysiology of nonalcoholic steatohepatitis (NASH). The present study evaluates the modulation of bile acid metabolomics by atorvastatin, a cholesterol-lowering agent commonly used to treat cardiovascular complications accompanying NASH. NASH was induced in mice by 24 weeks of consuming a high–saturated fat, high-fructose, and high-cholesterol diet (F), with atorvastatin administered orally (20 mg/kg/day) during the last three weeks. Biochemical and histological analyses confirmed the effectiveness of the F diet in inducing NASH. Untreated NASH animals had significantly reduced biliary secretion of BA and increased fecal excretion of BA via decreased apical sodium-dependent bile salt transporter (Asbt)-mediated reabsorption. Atorvastatin decreased liver steatosis and inflammation in NASH animals consistently with a reduction in crucial lipogenic enzyme stearoyl–coenzyme A (CoA) desaturase-1 and nuclear factor kappa light chain enhancer of activated B-cell pro-inflammatory signaling, respectively. In this group, atorvastatin also uniformly enhanced plasma concentration, biliary secretion and fecal excretion of the secondary BA, deoxycholic acid (DCA). However, in the chow diet–fed animals, atorvastatin decreased plasma concentrations of BA, and reduced BA biliary secretions. These changes stemmed primarily from the increased fecal excretion of BA resulting from the reduced Asbt-mediated BA reabsorption in the ileum and suppression of synthesis in the liver. In conclusion, our results reveal that atorvastatin significantly modulates BA metabolomics by altering their intestinal processing and liver synthesis in control and NASH mice.

Allopurinol ameliorates high fructose diet induced hepatic steatosis in diabetic rats through modulation of lipid metabolism, inflammation, and ER stress pathway

Excess fructose consumption contributes to development obesity, metabolic syndrome, and nonalcoholic fatty liver disease (NAFLD). Uric acid (UA), a metabolite of fructose metabolism, may have a direct role in development of NAFLD, with unclear mechanism. This study aimed to evaluate role of fructose and UA in NAFLD and explore mechanisms of allopurinol (Allo, a UA lowering medication) on NAFLD in Otsuka Long-Evans Tokushima Fatty (OLETF) rats fed a high fructose diet (HFrD), with Long-Evans Tokushima Otsuka (LETO) rats used as a control. There were six groups: LETO, LETO-Allo, OLETF, OLETF-Allo, OLETF-HFrD, and OLETF-HFrD-Allo. HFrD significantly increased body weight, epididymal fat weight, and serum concentrations of UA, cholesterol, triglyceride, HbA1c, hepatic enzymes, HOMA-IR, fasting insulin, and two hour-glucose after intraperitoneal glucose tolerance tests, as well as NAFLD activity score of liver, compared to the OLETF group. Allopurinol treatment significantly reduced hepatic steatosis, epididymal fat, serum UA, HOMA-IR, hepatic enzyme levels, and cholesterol in the OLETF-HFrD-Allo group. Additionally, allopurinol significantly downregulated expression of lipogenic genes, upregulated lipid oxidation genes, downregulated hepatic pro-inflammatory cytokine genes, and decreased ER-stress induced protein expression, in comparison with the OLETF-HFrD group. In conclusion, allopurinol ameliorates HFrD-induced hepatic steatosis through modulation of hepatic lipid metabolism, inflammation, and ER stress pathway. UA may have a direct role in development of fructose-induced hepatic steatosis, and allopurinol could be a candidate for prevention or treatment of NAFLD.

Acute and chronic effects of environmental realistic concentrations of simvastatin in danio rerio: evidences of oxidative alterations and endocrine disruptive activity

Due to their wide use, pharmaceuticals can be discarded, metabolized and excreted into the environment, potentially affecting aquatic organisms. Lipid-regulating drugs are among the most prescribed medications around the world, to control human cholesterol levels, in more than 20 million patients. Despite this massive use of lipid-regulating drugs, particularly simvastatin, the role of these drugs is not fully characterized and understood in terms of its potential toxicological effects at the environmental level. This work intended to characterize the toxicity of an acute (120 h post-fertilization) and chronic (60 days) exposure to the antihyperlipidemic drug simvastatin (in concentrations of 92.45, 184.9, 369.8, 739.6 and 1479.2 ng L^-1), in the freshwater species zebrafish (Danio rerio). The concentrations hereby mentioned were implemented in both exposures, and were based on levels found in wastewater treatment plant influents (11.7 ± 3.2 μg L^-1), effluents (2.65 ± 0.8 μg L^-1) and Apies River (1.585 ± 0.3 μg L^-1), located in Pretoria, South Africa and, particularly in the maximum levels found in effluents from wastewater treatment plants in Portugal (369.8 ng L^-1). The acute effects were analysed focusing on behavioural endpoints (erratic and purposeful swimming), total distance travelled and swimming time), biomarkers of oxidative stress (the activities of the enzymes superoxide dismutase, catalase, glutathione peroxidase), biotransformation (the activity of glutathione S-transferases) and lipid peroxidation (levels of thiobarbituric acid reactive substances). Animals chronically exposed were also histologically analysed for sex determination and gonadal developmental stages identification. In terms of acute exposure, significant alterations were reported in terms of behavioural alterations (hyperactivity), followed by a general reduction in all tested biomarkers. Also, the analysis of chronically exposed fish evidenced no alterations in sex ratio and maturation stages. In addition, the analysis of chronically exposed fish evidenced no alterations in terms of sexual characteristics, suggesting that the chronic exposure of Danio rerio to simvastatin does not alter the sex ratio and maturation stages of individuals. This assumption suggests that simvastatin did not act as an endocrine disruptor. Moreover, the metabolism, neuronal interactions and the antioxidant properties of SIM seem to have modulated the hereby-mentioned results of toxicity. Results from this assay allow inferring that simvastatin can have an ecologically relevant impact in living organisms.

Disease-associated gut microbiome and metabolome changes in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is the third commonest cause of death globally, and manifests as a progressive inflammatory lung disease with no curative treatment. The lung microbiome contributes to COPD progression, but the function of the gut microbiome remains unclear. Here we examine the faecal microbiome and metabolome of COPD patients and healthy controls, finding 146 bacterial species differing between the two groups. Several species, including Streptococcus sp000187445, Streptococcus vestibularis and multiple members of the family Lachnospiraceae, also correlate with reduced lung function. Untargeted metabolomics identifies a COPD signature comprising 46% lipid, 20% xenobiotic and 20% amino acid related metabolites. Furthermore, we describe a disease-associated network connecting Streptococcus parasanguinis_B with COPD-associated metabolites, including N-acetylglutamate and its analogue N-carbamoylglutamate. While correlative, our results suggest that the faecal microbiome and metabolome of COPD patients are distinct from those of healthy individuals, and may thus aid in the search for biomarkers for COPD.

Chronic obstructive pulmonary disease (COPD) is a progressing disease, with lung but not gut microbiota implicated in its etiology. Here the authors compare the stool from patients with COPD and healthy controls to find specific gut bacteria and metabolites associated with active disease, thereby hinting at a potential role for the gut microbiome in COPD.

Structural Basis for Activation of Human Sirtuin 6 by Fluvastatin

Sirtuins are NAD+-dependent protein lysine deacylases that are considered attractive drug targets for aging-related diseases. Sirt6 deacetylates, e.g., transcription factors and histone H3, and regulates metabolic processes and stress responses. It has been implicated in lifespan extension and tumor suppression. Sirt6 deacetylase activity can be stimulated with small molecules, and fluvastatin, an FDA-approved synthetic statin, was recently described as a novel Sirt6 activator. We studied the molecular details of this effect on Sirt6 in deacylation assays and by solving a crystal structure of a Sirt6/fluvastatin complex. We find that fluvastatin inhibits Sirt1-3 at higher concentrations but has a unique, activating effect on Sirt6. The complex structure reveals that fluvastatin occupies the Sirt6 substrate acyl channel exit, similar to other, unrelated activator families, providing interaction details that will support the development of potent, druglike Sirt6 activators.

Pleiotropic Effects of Statins in the Light of Non-Alcoholic Fatty Liver Disease and Non-Alcoholic Steatohepatitis

Statins, the lipid-lowering drugs, and non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH), a lipid-related pathology, share a complex relationship, one known to be hepatotoxic and other being hepatic injury. NASH is an unresolved mystery in terms of treatment. Could statins prove to be a promising solution due to their pleiotropic properties in addition to the cholesterol-lowering effect? This study aims to find statin effectiveness in NAFLD/NASH treatment and prevention of associated adverse outcomes. An extensive data search was done to identify the studies assessing statin effect on NAFLD/NASH and then analyzed to establish the relationship. Several studies demonstrated a reduction in NAFLD/NASH-associated inflammation and fibrosis with statin treatment. These anti-inflammatory and anti-fibrotic effects were through their pleiotropic properties, which were in addition to their cholesterol-lowering effect. In various animal studies, statins were found to improve hepatic lipotoxicity, oxidative stress, inflammatory responses, and fibrosis associated with NASH through multiple pathways. Statins exert these protective effects by recovering the gene expression level of peroxisomal proliferator-activated receptor alpha (PPARα) and therefore restore the mitochondrial and peroxisomal fatty acid oxidation (FAO). Statin treatment also increased the levels of paraoxonase 1 (PON1), an antioxidant and antiatherogenic enzyme that is reduced in NAFLD as well as encounter the hepatic lipotoxicity by resolving cholesterol crystals and Kupffer cells (KCs) with crown-like structures (CLSs). They exhibited antitumor properties by inhibiting proinflammatory cytokines and vascular proliferative factors. Moreover, they restored a healthy liver sinusoidal endothelial cell (LSEC) and hepatic stellate cells (HSC) along with inhibiting the activation of HSC via modulating inducible nitric oxide synthase (iNOS) and expressions of endothelial nitric oxide synthase (eNOS). Besides, they were protective against cardiovascular disease (CVD)-related morbidity and mortality, hepatocellular carcinoma (HCC), and metabolic syndrome (MS) associated with NAFLD/NASH. NASH and its precursor, NAFLD, could be treated and prevented with statins owing to their pleiotropic properties. This study helps to prove this by looking back at different literature and has successfully enlightened the point. Once proved through large clinical trials on humans, it could revolutionize the NASH therapy. 

Specificity of transaminase activities in the prediction of drug-induced hepatotoxicity

The activities of the transaminases (aminotransferases) alanine aminotransferase and aspartate aminotransferase in the blood (serum or plasma) are widely used as sensitive markers of possible tissue damage and, in particular for liver toxicity. On the other hand, an increase in transaminase activities is not always accompanied by findings suggestive of hepatotoxicity. Transaminases are some of the key enzymes in the gluconeogenesis and glycolysis pathways and exist in many organs and tissues which have high activities of the gluconeogenesis and glycolysis. The activities of transaminases are altered not only in the liver but also in other organs by modification of gluconeogenesis by nutritional or hormonal factors and this phenomenon leads to alteration of transaminase activity in the blood. Drugs, which are considered to directly or secondarily modify gluconeogenesis through lowering blood glucose levels or activating lipid metabolism, such as α-glucosidase inhibitors and fibrates, slightly increase transaminase activities in the blood but there is little evidence that the phenomenon is related to drug-induced liver injury (DILI). This type of elevations can be called pharmacology-related elevation. The pharmacology-related elevation of transaminase activities sometimes makes it difficult to assess precisely the potential hepatotoxicity of new investigational drugs. Considering the characteristic of transaminases, concomitant use of new biomarkers more specific to hepatic injury is needed in the assessment of DILI both in non-clinical and clinical studies. In this review, we will discuss the specificity of transaminases to DILI and future perspectives for transaminases in the estimation of risk of DILI.

NADPH Oxidase Inhibition in Fibrotic Pathologies

Significance: Fibrosis is a stereotypic, multicellular tissue response to diverse types of injuries that fundamentally result from a failure of cell/tissue regeneration. This complex tissue remodeling response disrupts cellular/matrix composition and homeostatic cell-cell interactions, leading to loss of normal tissue architecture and progressive loss of organ structure/function. Fibrosis is a common feature of chronic diseases that may affect the lung, kidney, liver, and heart. Recent Advances: There is emerging evidence to support a combination of genetic, environmental, and age-related risk factors contributing to susceptibility and/or progression of fibrosis in different organ systems. A core pathway in fibrogenesis involving these organs is the induction and activation of nicotinamide adenine dinucleotide phosphate oxidase (NOX) family enzymes. Critical Issues: We explore current pharmaceutical approaches to targeting NOX enzymes, including repurposing of currently U.S. Food and Drug Administration (FDA)-approved drugs. Specific inhibitors of various NOX homologs will aid establishing roles of NOXs in the various organ fibroses and potential efficacy to impede/halt disease progression. Future Directions: The discovery of novel and highly specific NOX inhibitors will provide opportunities to develop NOX inhibitors for treatment of fibrotic pathologies.

Current and emerging pharmacotherapeutic interventions for the treatment of liver fibrosis

INTRODUCTION

Chronic liver disease is due to various causes of persistent liver damage and will eventually lead to the development of liver fibrosis. If no treatment is initiated, this condition may progress to cirrhosis and hepatocellular carcinoma. Current treatments comprise the elimination of the cause of injury, such as by lifestyle changes, alcohol abstinence, and antiviral agents. However, such etiology-driven therapy is often insufficient in patients with late-stage fibrosis/cirrhosis, therefore maintaining the need for efficient antifibrotic pharmacotherapeutic interventions.

AREAS COVERED

The authors discuss the recent advances in the development of antifibrotic drugs, which target various pathways of the fibrogenesis process, including cell death, inflammation, gut-liver axis, and myofibroblast activation. Due to the significant burden of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH), various agents which specifically target metabolic pathways and their related receptors/ligands have been developed. For some of them, e.g., obeticholic acid, advanced stage clinical trials indicate antifibrotic efficacy in NAFLD and NASH.

EXPERT OPINION

Significant advances have been made in the development of novel antifibrotic pharmacotherapeutics. The authors expect that the development of combinatorial therapies, which combine compounds that target various pathways of fibrosis progression, will have a major impact as future etiology-independent therapies.

The Influence of Statins on the Aerobic Metabolism of Endothelial Cells

Endothelial mitochondrial dysfunction is considered to be the main cause of cardiovascular disease. The aim of this research was to elucidate the effects of cholesterol-lowering statins on the aerobic metabolism of endothelial cells at the cellular and mitochondrial levels. In human umbilical vein endothelial cells (EA.hy926), six days of exposure to 100 nM atorvastatin (ATOR) induced a general decrease in mitochondrial respiration. No changes in mitochondrial biogenesis, cell viability, or ATP levels were observed, whereas a decrease in Coenzyme Q10 (Q10) content was accompanied by an increase in intracellular reactive oxygen species (ROS) production, although mitochondrial ROS production remained unchanged. The changes caused by 100 nM pravastatin were smaller than those caused by ATOR. The ATOR-induced changes at the respiratory chain level promoted increased mitochondrial ROS production. In addition to the reduced level of mitochondrial Q10, the activity of Complex III was decreased, and the amount of Complex III in a supercomplex with Complex IV was diminished. These changes may cause the observed decrease in mitochondrial membrane potential and an increase in Q10 reduction level as a consequence, leading to elevated mitochondrial ROS formation. The above observations highlight the role of endothelial mitochondria in response to potential metabolic adaptations related to the chronic exposure of endothelial cells to statins.

Impaired Peroxisomal Fitness in Obese Mice, a Vicious Cycle Exacerbating Adipocyte Dysfunction via Oxidative Stress

Aims: Peroxisome is a critical organelle for fatty acid oxidation (FAO) and metabolism of reactive oxygen species (ROS). Increased oxidative stress in adipose tissue contributes to the development of insulin resistance and metabolic syndrome in obesity. This study aimed to investigate the role of peroxisomal fitness in maintaining adipocyte function, which has been under-rated in the obesity research area. Results: Reduced peroxisomal gene expressions in white adipose tissue (WAT) of obese mice suggested a close correlation between peroxisomes and obesity. Peroxisomal biogenesis factor 5 siRNA increased cellular ROS and inflammatory mediators in 3T3-L1 adipocytes. On the contrary, hydrogen peroxide or tumor necrosis factor-α treatment significantly decreased biogenesis- and function-related peroxisomal proteins, suggesting a positive feedback loop of ROS/inflammation and peroxisomal dysfunction. Correspondingly, catalase (a major peroxisomal antioxidant)-knockout mice fed with high-fat diet (HFD) exhibited suppressed peroxisomal proteins along with increased oxidative stress and accelerated obesity. In response to fenofibrate (a peroxisomal proliferator) treatment, WAT of HFD-fed wild-type mice showed not only increases in peroxisomal biogenesis and FAO but also attenuated features of adipocyte dysfunction and obesity. However, these results were not observed in peroxisome proliferator-activated receptor-alpha null obese mice. Innovation: Impaired peroxisomal fitness enhanced oxidative stress and inflammation in adipocytes, which exacerbates obesity. Conclusion: Adipose tissue peroxisomal homeostasis plays an important role in attenuating the features of obesity, and it can be a potential therapeutic target of obesity.