The PPAR α/γ Agonist Saroglitazar Improves Insulin Resistance and Steatohepatitis in a Diet Induced Animal Model of Nonalcoholic Fatty Liver Disease

Hepatic glucagon action: beyond glucose mobilization

Glucagon's ability to promote hepatic glucose production has been known for over a century, with initial observations touting this hormone as a diabetogenic agent. However, glucagon receptor agonism [when balanced with an incretin, including glucagon-like peptide 1 (GLP-1) to dampen glucose excursions] is now being developed as a promising therapeutic target in the treatment of metabolic diseases, like metabolic dysfunction-associated steatotic disease/metabolic dysfunction-associated steatohepatitis (MASLD/MASH), and may also have benefit for obesity and chronic kidney disease. Conventionally regarded as the opposing tag-team partner of the anabolic mediator insulin, glucagon is gradually emerging as more than just a "catabolic hormone." Glucagon action on glucose homeostasis within the liver has been well characterized. However, growing evidence, in part thanks to new and sensitive "omics" technologies, has implicated glucagon as more than just a "glucose liberator." Elucidation of glucagon's capacity to increase fatty acid oxidation while attenuating endogenous lipid synthesis speaks to the dichotomous nature of the hormone. Furthermore, glucagon action is not limited to just glucose homeostasis and lipid metabolism, as traditionally reported. Glucagon plays key regulatory roles in hepatic amino acid and ketone body metabolism, as well as mitochondrial turnover and function, indicating broader glucagon signaling consequences for metabolic homeostasis mediated by the liver. Here we examine the broadening role of glucagon signaling within the hepatocyte and question the current dogma, to appreciate glucagon as more than just that "catabolic hormone."

The role of lipid metabolism in osteoporosis: Clinical implication and cellular mechanism

In recent years, researchers have become focused on the relationship between lipids and bone metabolism balance. Moreover, many diseases related to lipid metabolism disorders, such as nonalcoholic fatty liver disease, atherosclerosis, obesity, and menopause, are associated with osteoporotic phenotypes. It has been clinically observed in humans that these lipid metabolism disorders promote changes in osteoporosis-related indicators bone mineral density and bone mass. Furthermore, similar osteoporotic phenotype changes were observed in high-fat and high-cholesterol-induced animal models. Abnormal lipid metabolism (such as increased oxidized lipids and elevated plasma cholesterol) affects bone microenvironment homeostasis via cross-organ communication, promoting differentiation of mesenchymal stem cells to adipocytes, and inhibiting commitment towards osteoblasts. Moreover, disturbances in lipid metabolism affect the bone metabolism balance by promoting the secretion of cytokines such as receptor activator of nuclear factor-kappa B ligand by osteoblasts and stimulating the differentiation of osteoclasts. Conclusively, this review addresses the possible link between lipid metabolism disorders and osteoporosis and elucidates the potential modulatory mechanisms and signaling pathways by which lipid metabolism affects bone metabolism balance. We also summarize the possible approaches and prospects of intervening lipid metabolism for osteoporosis treatment.

Deciphering the molecular pathways of saroglitazar: A dual PPAR α/γ agonist for managing metabolic NAFLD

Saroglitazar (SARO), a dual peroxisome proliferator activated receptor (PPAR)-α/γ agonist, has been used to treat metabolic diseases such as insulin resistance and diabetic dyslipidemia in patients with non-alcoholic fatty liver disease (NAFLD). SARO, administered at a dose of 4 mg/day, has been consistently studied in clinical trials with different time points ranging from 4 to 24 weeks with NAFLD patients. Due to its PPAR-γ agonistic action, SARO prevents adipose tissue-mediated fatty acid delivery to the liver by increasing insulin sensitivity and regulating adiponectin and leptin levels in adipose tissue. In hepatocytes, SARO induces fatty acid β-oxidation in mitochondria and transcriptionally activates lipid metabolizing genes in peroxisomes. SARO inhibits insulin resistance, thereby preventing the activation of sterol regulatory element-binding proteins -1c and carbohydrate response element binding protein in hepatocytes through its PPAR-α agonistic action. SARO treatment reduces lipotoxicity-mediated oxidative stress by activating the nuclear factor erythroid 2-related factor 2 and transcriptionally expressing the antioxidants from the antioxidant response element in the nucleus through its PPAR-γ agonistic action. SARO provides a PPAR-α/γ-mediated anti-inflammatory effect by preventing the phosphorylation of mitogen-activated protein kinases (JNK and ERK) and nuclear factor kappa B in hepatocytes. Additionally, SARO interferes with transforming growth factor-β/Smad downstream signaling, thereby reducing liver fibrosis progression through its PPAR-α/γ agonistic actions. Thus, SARO improves insulin resistance and dyslipidemia in NAFLD, reduces lipid accumulation in the liver, and thereby prevents mitochondrial toxicity, oxidative stress, inflammation, and fibrosis progression. This review summarizes the possible molecular mechanism of SARO in the NAFLD.

Indigenous wisdom of a Kwatha to treat NASH: An insight into the mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Nonalcoholic fatty liver disease (NAFLD) is the most common severe liver disease globally, progressing further into nonalcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC). Vasaguduchyadi Kwatha (VK) is an Ayurvedic formulation traditionally used to treat liver diseases and other metabolic complications. This study is an ethnopharmacological approach to unravel this indigenous remedy.

AIM OF THE STUDY

We aimed to discover the probable mechanism of action of VK against NASH in this study, using network pharmacology, molecular docking, in vitro study, and preclinical investigation.

METHODS AND RESULTS

Among the 55 components identified, 10 were confirmed based on mass, elution charecteristics, MS/MS analysis data, and fragmentation rules. Computational study indicated 92 targets involved in the central pathways of NASH, out of which only 15 targets and 9 VK constituents have significant docking scores. In vitro and in vivo analysis results showed that VK significantly reduces weight gain and improves insulin sensitivity, dyslipidemia, steatohepatitis and overall histological features of NASH compared to saroglitazar (SGZR).

CONCLUSION

Our detailed study yielded three signalling pathways related to NASH on which VK has maximum effect, bringing up a probable alternative treatment for NASH.

Alleviation of pulmonary fibrosis by the dual PPAR agonist saroglitazar and breast milk mesenchymal stem cells via modulating TGFß/SMAD pathway

Pulmonary fibrosis (PF) is a complex disorder with high morbidity and mortality. Limited efficacies of the available drugs drive researchers to seek for new therapies. Saroglitazar (Saro), a full (PPAR α/γ) agonist, is devoid of known PPAR-mediated adverse effects. Breast milk mesenchymal stem cells (BrMSCs) are contemplated to be the ideal cell type harboring differentiation/anti-inflammatory/immunosuppressive properties. Accordingly, our aims were to investigate the potential roles of Saro and/or BrMSCs in PF and to spot their underlying protective mechanisms. In this study, PF was induced by bleomycin (BLM) via intratracheal instillation. Treatment started 14 days later. Animals were treated with oral saroglitazar (3 mg/kg daily) or intraperitoneal single BrMSCs injection (0.5 ml phosphate buffer saline (PBS) containing 2 × 107 cells) or their combination with same previous doses. At the work end, 24 h following the 6 weeks of treatment period, the levels of oxidative (MDA, SOD), inflammatory (IL-1ß, IL-10), and profibrotic markers (TGF-ß, αSMA) were assessed. The autophagy-related genes (LC3, Beclin) and the expression of PPAR-α/γ and SMAD-3/7 were evaluated. Furthermore, immunohistochemical and histological work were evaluated. Our study revealed marked lung injury influenced by BLM with severe oxidative/inflammatory/fibrotic damage, autophagy inhibition, and deteriorated lung histology. Saro and BrMSCs repaired the lung structure worsened by BLM. Treatments greatly declined the oxidative/inflammatory markers. The pro-fibrotic TGF-ß, αSMA, and SMAD-3 were decreased. Contrarily, autophagy markers were increased. SMAD-7 and PPAR α/γ were activated denoting their pivotal antifibrotic roles. Co-administration of Saro and BrMSCs revealed the top results. Our findings support the study hypothesis that Saro and BrMSCs can be proposed as potential treatments for IPF.

Intervention effect of Cigu Xiaozhi prescription on ceramide lipoapoptosis in non-alcoholic fatty liver disease

OBJECTIVE

To explore the mechanism of the Chinese medicine Cigu Xiaozhi prescription (, CGXZ) in the treatment of the non-alcoholic fatty liver disease (NAFLD) by detoxification and phlegm-reducing, the effect of CGXZ prescription on ceramide-mediated lipid apoptosis in Hep G2 cells with NAFLD.

METHODS

The experiment was randomly divided into 6 groups: normal control group, model group, CGXZ prescription medicated serum high, medium, and low dose groups, and pioglitazone positive control group. Using 500 μmol/L free fatty acid (FFA) mixture to induce Hep G2 cells to establish NAFLD cell model, respectively, with 2%, 4%, and 6% concentration of CGXZ prescription medicated serum intervention for 24 h. The changes in organelles and lipid droplet accumulation were observed under the electron microscope. Furthermore, TdT-mediated dUTP Nick-End Labeling method was used to assay hepatocyte apoptosis; Biochemical determination of glutamic-pyruvic transaminase, glutamic oxalacetic transaminase, triglycerides, and FFA levels in Hep G2 cells; the content of ceramide was determined by high-performance thin-layer chromatography. Finally, Western Blot and quantitative real-time polymerase chain reaction (qRT-PCR) were used to determine the protein and gene expression levels, such as inducible nitric oxide synthase (iNOS), nuclear factor κB (NF-κB), B cell lymphoma 2 (Bcl-2) and Bcl-2-associated X (Bax).

RESULTS

Under the electron microscope, the cells in the model group showed moderate-to-severe steatosis, and apoptotic bodies could be seen. The model group had greater improvements in the apoptosis rate (P < 0.01), and the levels of ceramide C2 and FFA in the cytoplasm (P < 0.01) than the normal control group. The protein expressions of NF-κB, iNOS, and Bax were significantly up-regulated (P < 0.05), while the Bcl-2 had no significant change (P > 0.05). Compared with the model group, the levels of ceramide C2 and FFA (P < 0.01), the protein expressions of NF-κB, iNOS, and Bax (P < 0.05) in the CGXZ prescription treatment group and pioglitazone positive control group were significantly decreased; Only the Bcl-2 protein was significantly up-regulated in the high-dose Chinese medicine group (P < 0.05). The down-regulation of Bax mRNA expression in each Chinese medicine treatment group was significantly better than in the pioglitazone positive control group (P < 0.01).

CONCLUSIONS

The CGXZ prescription, formulated with the method of detoxification and phlegm, can inhibit lipoapoptosis in the NAFLD cell model by down-regulating the levels of ceramide C2 and FFA, which may be achieved by regulating ceramide/iNOS/NF-κB signaling pathway.

Peroxisome proliferator-activated receptors: A key link between lipid metabolism and cancer progression

Lipids represent the essential components of membranes, serve as fuels for high-energy processes, and play crucial roles in signaling and cellular function. One of the key hallmarks of cancer is the reprogramming of metabolic pathways, especially abnormal lipid metabolism. Alterations in lipid uptake, lipid desaturation, de novo lipogenesis, lipid droplets, and fatty acid oxidation in cancer cells all contribute to cell survival in a changing microenvironment by regulating feedforward oncogenic signals, key oncogenic functions, oxidative and other stresses, immune responses, or intercellular communication. Peroxisome proliferator-activated receptors (PPARs) are transcription factors activated by fatty acids and act as core lipid sensors involved in the regulation of lipid homeostasis and cell fate. In addition to regulating whole-body energy homeostasis in physiological states, PPARs play a key role in lipid metabolism in cancer, which is receiving increasing research attention, especially the fundamental molecular mechanisms and cancer therapies targeting PPARs. In this review, we discuss how cancer cells alter metabolic patterns and regulate lipid metabolism to promote their own survival and progression through PPARs. Finally, we discuss potential therapeutic strategies for targeting PPARs in cancer based on recent studies from the last five years.

New Therapeutic Approaches for the Treatment of Patients with Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) and Increased Cardiovascular Risk

Metabolic dysfunction-associated steatotic liver disease (MASLD) was previously known as nonalcoholic fatty liver disease (NAFLD). The main characteristic of the disease is the process of long-term liver inflammation, which leads to hepatocyte damage followed by liver fibrosis and eventually cirrhosis. Additionally, these patients are at a greater risk for developing cardiovascular diseases (CVD). They have several pathophysiological mechanisms in common, primarily lipid metabolism disorders and lipotoxicity. Lipotoxicity is a factor that leads to the occurrence of heart disease and the occurrence and progression of atherosclerosis. Atherosclerosis, as a multifactorial disease, is one of the predominant risk factors for the development of ischemic heart disease. Therefore, CVD are one of the most significant carriers of mortality in patients with metabolic syndrome. So far, no pharmacotherapy has been established for the treatment of MASLD, but patients are advised to reduce their body weight and change their lifestyle. In recent years, several trials of different drugs, whose basic therapeutic indications include other diseases, have been conducted. Because it has been concluded that they can have beneficial effects in the treatment of these conditions as well, in this paper, the most significant results of these studies will be presented.

The Role of Nuclear Receptors in the Pathogenesis and Treatment of Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a global health burden closely linked to insulin resistance, obesity, and type 2 diabetes. The complex pathophysiology of NAFLD involves multiple cellular pathways and molecular factors. Nuclear receptors (NRs) have emerged as crucial regulators of lipid metabolism and inflammation in NAFLD, offering potential therapeutic targets for NAFLD. Targeting PPARs and FXRs has shown promise in ameliorating NAFLD symptoms and halting disease progression. However, further investigation is needed to address side effects and personalize therapy approaches. This review summarizes the current understanding of the involvement of NRs in the pathogenesis of NAFLD and explores their therapeutic potential. We discuss the role of several NRs in modulating lipid homeostasis in the liver, including peroxisome proliferator-activated receptors (PPARs), liver X receptors (LXRs), farnesoid X receptors (FXRs), REV-ERB, hepatocyte nuclear factor 4α (HNF4α), constitutive androstane receptor (CAR) and pregnane X receptor (PXR).The expanding knowledge of NRs in NAFLD offers new avenues for targeted therapies, necessitating exploration of novel treatment strategies and optimization of existing approaches to combat this increasingly prevalent disease.

Apoptosis antagonizing transcription factor-mediated liver damage and inflammation to cancer: Therapeutic intervention by curcumin in experimental metabolic dysfunction associated steatohepatitis-hepatocellular carcinoma

In tandem with the expanding obesity pandemic, the prevalence of metabolic dysfunction associated steatohepatitis (MASH, formerly known as NASH)- driven hepatocellular carcinoma (HCC) is predicted to rise globally, creating a significant need for therapeutic interventions. We previously identified the upregulation of apoptosis antagonizing transcription factor (AATF), which is implicated in facilitating the progression from MASH to HCC. The objective of this study was to examine whether the intervention of curcumin could alleviate AATF-mediated MASH, inhibit tumor growth, and elucidate the underlying mechanism. A preclinical murine model mimicking human MASH-HCC was employed, subjecting mice to either a chow diet normal water (CDNW) or western diet sugar water (WDSW) along with very low dose of carbon tetrachloride (CCl4 - 0.2 μL/g, weekly). Mice receiving curcumin (CUR) alongside WDSW/CCl4 exhibited significant improvements, including reduced liver enzymes, dyslipidemia, steatosis, inflammation, and hepatocellular ballooning. Curcumin treatment also suppressed hepatic expression of inflammatory, fibrogenic, and oncogenic markers. Of note, there was a significant reduction in the expression of AATF upon curcumin treatment in WDSW/CCl4 mice and human HCC cells. In contrast, curcumin upregulated Kruppel-like factor 4 (KLF4) in MASH liver and HCC cells, which is known to downregulate sp1 (specificity protein-1) expression. Thus, curcumin treatment effectively inhibited the progression of MASH to HCC by downregulating the expression of AATF via the KLF4-Sp1 signaling pathway. These preclinical findings establish a novel molecular connection between curcumin and AATF in reducing hepatocarcinogenesis, and provide a strong rationale for the development of curcumin as a viable treatment for MASH-HCC in humans.

Molecular mechanisms of alcohol's effects on the human body: A review and update

Alcohol consumption has been linked to numerous negative health outcomes although it has some beneficial effects on moderate dosages, the most severe of which being alcohol-induced hepatitis. The number of people dying from this liver illness has been shown to climb steadily over time, and its prevalence has been increasing. Researchers have found that alcohol consumption primarily affects the brain, leading to a wide range of neurological and psychological diseases. High-alcohol-consumption addicts not only experienced seizures, but also ataxia, aggression, social anxiety, and variceal hemorrhage that ultimately resulted in death, ascites, and schizophrenia. Drugs treating this liver condition are limited and can cause serious side effects like depression. Serine-threonine kinases, cAMP protein kinases, protein kinase C, ERK, RACK 1, Homer 2, and more have all been observed to have their signaling pathways disrupted by alcohol, and alcohol has also been linked to epigenetic changes. In addition, alcohol consumption induces dysbiosis by changing the composition of the microbiome found in the gastrointestinal tract. Although more studies are needed, those that have been done suggest that probiotics aid in keeping the various microbiota concentrations stable. It has been argued that reducing one's alcohol intake may seem less harmful because excessive drinking is a lifestyle disorder.

The Protective Effects of Cinnamyl Alcohol Against Hepatic Steatosis, Oxidative and Inflammatory Stress in Nonalcoholic Fatty Liver Disease Induced by Childhood Obesity

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive intracellular lipid accumulation, oxidative stress, and inflammation. Cinnamyl alcohol (CA), one of the cinnamon extracts, has been shown to exhibit anti-oxidative and anti-inflammatory activities. We proposed that CA was beneficial to NAFLD.

METHODS

Serum cytokines and components of the lipid metabolism were determined in children with NAFLD against age-matched comparisons. A NAFLD mouse model was established by high fat and high carbohydrate (HFHC) diet in male C57BL/6 mouse pups, followed by administration of CA. The effects of CA on lipid metabolism, oxidative stress, and inflammation in hepatic tissues were assessed.

RESULTS

Abnormal lipid metabolism and inflammatory responses were observed in the children with NAFLD as compared with the controls. CA reduced the weight of obese mice without affecting food intake as well as alleviating liver injury caused by HFHC feeding. CA was found to mitigate dyslipidemia and reduce hepatic steatosis in HFHC-fed mice by down-regulating genes related to lipogenesis, including peroxisome proliferator-activated receptor gamma (PPARγ), sterol regulatory element-binding transcription factor-1c (SREBP-1c), and acetyl-CoA carboxylase 1 (ACC1). Additionally, CA treatment reversed HFHC-induced oxidative stress and inflammation, evidenced by the decreased liver reactive oxygen species (ROS), hepatic inflammatory cytokine levels, and F4/80-positive macrophage infiltration in HFHC diet mice. CA reduced the protein levels of pyrin domain-containing protein 3 (NLRP3), adapter protein apoptosis-associated speck-like protein (ASC), and caspase-1 in the liver tissues significantly.

CONCLUSION

CA alleviates HFHC-induced NAFLD in mice, which is associated with the amelioration in lipid metabolism, oxidative stress, and inflammation.

Effect of herbal extracts and Saroglitazar on high-fat diet-induced obesity, insulin resistance, dyslipidemia, and hepatic lipidome in C57BL/6J mice

We evaluated the effects of select herbal extracts (Tinospora cordifolia [TC], Tinospora cordifolia with Piper longum [TC + PL], Withania somnifera [WS], Glycyrrhiza glabra [GG], AYUSH-64 [AY-64], and Saroglitazar [S]) on various parameters in a diet-induced obesity mouse model. After 12 weeks of oral administration of the herbal extracts in high-fat diet (HFD)-fed C57BL/6J mice, we analyzed plasma biochemical parameters, insulin resistance (IR), liver histology, and the expression of inflammatory and fibrosis markers, along with hepatic lipidome. We also used a 3D hepatic spheroid model to assess their impact on profibrotic gene expression. Among the extracts, TC + PL showed a significant reduction in IR, liver weight, TNF-α, IL4, IL10 expression, and hepatic lipid levels (saturated triglycerides, ceramides, lysophosphocholines, acylcarnitines, diglycerides, and phosphatidylinositol levels). Saroglitazar reversed changes in body weight, IR, plasma triglycerides, glucose, insulin, and various hepatic lipid species (fatty acids, phospholipids, glycerophospholipids, sphingolipids, and triglycerides). With the exception of GG, Saroglitazar, and other extracts protected against palmitic acid-induced fibrosis marker gene expression in the 3D spheroids. TC + PL and Saroglitazar also effectively prevented HFD-induced insulin resistance, inflammation, and specific harmful lipid species in the liver.

Exploration of potential targets and mechanisms of naringenin in the treatment of nonalcoholic fatty liver disease through network pharmacology

OBJECTIVE

This study aimed to use network pharmacology to investigate the molecular mechanisms and potential targets of naringenin (NR) for nonalcoholic fatty liver disease (NAFLD) treatment to offer new drug development ideas.

METHODS

The structure and compound information of NR were obtained from PubChem and the traditional Chinese medicine system pharmacology database and analysis platform. The traditional Chinese medicine system pharmacology database and analysis platform Database, Comparative Toxicogenomics Database and Encyclopedia of Traditional Chinese Medicine Database were then used to predict the related targets of NR. Online mendelian inheritance in man, Disgenet, Gene cards, The therapeutic target database and Drug bank were used to screen NAFLD targets, and the intersection analysis was performed with the targets of NR active components to obtain the targets of NR in the treatment of NAFLD. The protein-protein interaction network of therapeutic targets was constructed by protein-protein interaction networks functional enrichment analysis 11.0, and gene ontology (GO) functional enrichment analysis and Kyoto encyclopedia of genes and genomes pathway enrichment analysis of therapeutic targets was performed by Metascape platform.

RESULTS

In this study, 171 NR targets and 1748 potential targets of NAFLD were screened, and 89 crossover targets and 16 core targets were screened and finally obtained. A total of 176 GO items were obtained by GO enrichment analysis (P < .05), including 389 biological process, 6 cell composition and 30 molecular function. A total of 137 signaling pathways were obtained by Kyoto encyclopedia of genes and genomes pathway enrichment and screening (P < .05). The core targets of NR in the treatment of NAFLD are TP53, CASP3, PRKCA, AKT1, RELA, PPARG, NCOA2, CYP1A1, ESR1, MAPK3, STAT3, JAK1, MAPK1, TNF, PPARA and PRKCB. Enrichment analysis showed that NR mainly involved in biological processes such as cellular response to nitrogen compound, regulation of miRNA transcription and negative regulation of miRNA-mediated gene silencing. It regulates Hepatitis B, Lipid and atherosclerosis, cytomegalovirus infection, Hepatitis C, AGE-RAGE signaling pathway in diabetic patients complications and other ways play a role in the treatment of NAFLD.

CONCLUSIONS

The therapeutic effect of NR on NAFLD has the characteristics of multi-targets and multi-pathways, which provides a preliminary theoretical basis for clinical trials and the development of new drugs.

Saroglitazar in Non-alcoholic Fatty Liver Disease From Bench to Bedside: A Comprehensive Review and Sub-group Meta-Analysis

Non-alcoholic fatty liver disease (NAFLD) has become one of the most common causes of liver diseases globally, with a projected exponential rise. In contrast to the exponential rise in disease burden, there are limited options in the pharmacotherapeutic armamentarium against NAFLD. Saroglitazar belongs to the class of drugs known as peroxisome proliferator-activated receptor (PPAR) agonists, initially introduced for managing diabetic dyslipidemia. However, based on translational and clinical studies, it has been shown to be efficacious in NAFLD. It has been shown to modify key parameters in NAFLD, including reduction of transaminase levels, improvement in overall metabolic health, reduction of liver fat content, and improvement of liver stiffness and histology. Given the promising results, it has been made a part of society's guidelines in the therapeutic management of NAFLD. However, there remains a dearth of detailed reviews encompassing both pre-clinical and clinical data on the effectiveness of saroglitazar in NAFLD. In this review, we comprehensively review the pharmacology, pre-clinical data, and clinical studies on saroglitazar usage in NAFLD and conduct a subgroup meta-analysis of studies focussing on the impact of saroglitazar on liver stiffness changes.

The Role of Tumor Necrosis Factor-Alpha in the Pathogenesis and Treatment of Nonalcoholic Fatty Liver Disease

PURPOSE OF REVIEW

To summarize experimental and clinical evidence on the association between tumor necrosis factor-α (TNF-α) and nonalcoholic fatty liver disease (NAFLD) and discuss potential treatment considerations.

RECENT FINDINGS

Experimental evidence suggests that TNF-α is a cytokine with a critical role in the pathogenesis of NAFLD. Although, the production of TNF-α may be an early event during the course of nonalcoholic fatty liver (NAFL), TNF-α may play a more substantial role in the pathogenesis of nonalcoholic steatohepatitis (NASH) and NAFLD-associated fibrosis. Moreover, TNF-α may potentiate hepatic insulin resistance, thus interconnecting inflammatory with metabolic signals and possibly contributing to the development of NAFLD-related comorbidities, including cardiovascular disease, hepatocellular carcinoma, and extra-hepatic malignancies. In clinical terms, TNF-α is probably associated with the severity of NAFLD; circulating TNF-α gradually increases from controls to patients with NAFL, and then, to patients with NASH. Given this potential association, various therapeutic interventions (obeticholic acid, peroxisome proliferator-activated receptors, sodium-glucose co-transporter 2 inhibitors, glucagon-like peptide-1 receptor agonists, probiotics, synbiotics, rifaximin, vitamin E, pentoxifylline, ursodeoxycholic acid, fibroblast growth factor-21, n-3 polyunsaturated fatty acids, statins, angiotensin receptor blockers) have been evaluated for their effect on TNF-α and NAFLD. Interestingly, anti-TNF biologics have shown favorable metabolic and hepatic effects, which may open a possible therapeutic window for the management of advanced NAFLD. The potential key pathogenic role of TNF-α in NAFLD warrants further investigation and may have important diagnostic and therapeutic implications.

Pharmaceutical Strategies to Improve Druggability of Potential Drug Candidates in Nonalcoholic Fatty Liver Disease Therapy

Nonalcoholic fatty liver disease (NAFLD) has become globally prevalent and is the leading cause of chronic liver disease. Although NAFLD is reversible without medical intervention in the early stage, the condition could be sequentially worsened to nonalcoholic steatohepatitis (NASH) and, eventually, cirrhosis and hepatic cancer. The progression of NAFLD is related to various factors such as genetics, pre-disposed metabolic disorders, and immunologic factors. Thankfully, to date, there have been accumulating research efforts and, as a result, different classes of potent drug candidates have been discovered. In addition, there have also been various attempts to explore pharmaceutical strategies to improve the druggability of drug candidates. In this review, we provided a brief overview of the drug candidates that have undergone clinical trials. In the latter part, strategies for developing better drugs are discussed.

Antioxidant Peptides from Monkfish Swim Bladders: Ameliorating NAFLD In Vitro by Suppressing Lipid Accumulation and Oxidative Stress via Regulating AMPK/Nrf2 Pathway

In this study, we investigate the ameliorating functions of QDYD (MSP2), ARW (MSP8), DDGGK (MSP10), YPAGP (MSP13) and DPAGP (MSP18) from monkfish swim bladders on an FFA-induced NAFLD model of HepG2 cells. The lipid-lowering mechanisms revealed that these five oligopeptides can up-regulate the expression of phospho-AMP-activated protein kinase (p-AMPK) proteins to inhibit the expression of the sterol regulatory element binding protein-1c (SREBP-1c) proteins on increasing lipid synthesis and up-regulating the expression of the PPAP-α and CPT-1 proteins on promoting the β-oxidation of fatty acids. Moreover, QDYD (MSP2), ARW (MSP8), DDGGK (MSP10), YPAGP (MSP13) and DPAGP (MSP18) can significantly inhibit reactive oxygen species' (ROS) production, promote the activities of intracellular antioxidases (superoxide dismutase, SOD; glutathione peroxidase, GSH-PX; and catalase, CAT) and bring down the content of malondialdehyde (MDA) derived from lipid peroxidation. Further investigations revealed that the regulation of these five oligopeptides on oxidative stress was achieved through activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway to raise the expression levels of the heme oxygenase 1 (HO-1) protein and downstream antioxidant proteases. Therefore, QDYD (MSP2), ARW (MSP8), DDGGK (MSP10), YPAGP (MSP13) and DPAGP (MSP18) could serve as candidate ingredients to develop functional products for treating NAFLD.

Targeting PPARs for therapy of atherosclerosis: A review

Atherosclerosis, a chief pathogenic factor of cardiovascular disease, is associated with many factors including inflammation, dyslipidemia, and oxidative stress. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors and are widely expressed with tissue- and cell-specificity. They control multiple genes that are involved in lipid metabolism, inflammatory response, and redox homeostasis. Given the diverse biological functions of PPARs, they have been extensively studied since their discovery in 1990s. Although controversies exist, accumulating evidence have demonstrated that PPAR activation attenuates atherosclerosis. Recent advances are valuable for understanding the mechanisms of action of PPAR activation. This article reviews the recent findings, mainly from the year of 2018 to present, including endogenous molecules in regulation of PPARs, roles of PPARs in atherosclerosis by focusing on lipid metabolism, inflammation, and oxidative stress, and synthesized PPAR modulators. This article provides information valuable for researchers in the field of basic cardiovascular research, for pharmacologists that are interested in developing novel PPAR agonists and antagonists with lower side effects as well as for clinicians.

Current, emerging, and potential therapies for non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) has been identified as the most common chronic liver disease worldwide, with a growing incidence. NAFLD is considered the hepatic manifestation of a metabolic syndrome that emerges from multiple factors (e.g., oxidative stress, metabolic disorders, endoplasmic reticulum stress, cell death, and inflammation). Non-alcoholic steatohepatitis (NASH), an advanced form of NAFLD, has been reported to be a leading cause of cirrhosis and hepatic carcinoma, and it is progressing rapidly. Since there is no approved pharmacotherapy for NASH, a considerable number of therapeutic targets have emerged with the deepening of the research on NASH pathogenesis. In this study, the therapeutic potential and properties of regulating metabolism, the gut microbiome, antioxidant, microRNA, inhibiting apoptosis, targeting ferroptosis, and stem cell-based therapy in NASH are reviewed and evaluated. Since the single-drug treatment of NASH is affected by individual heterogeneous responses and side effects, it is imperative to precisely carry out targeted therapy with low toxicity. Lastly, targeted therapeutic agent delivery based on exosomes is proposed in this study, such that drugs with different mechanisms can be incorporated to generate high-efficiency and low-toxicity individualized medicine.

PPAR-γ signaling in nonalcoholic fatty liver disease: Pathogenesis and therapeutic targets

Non-alcoholic fatty liver disease (NAFLD), currently the leading cause of global chronic liver disease, has emerged as a major public health problem, more efficient therapeutics of which are thus urgently needed. Peroxisome proliferator-activated receptor γ (PPAR-γ), ligand-activated transcription factors of the nuclear hormone receptor superfamily, is considered a crucial metabolic regulator of hepatic lipid metabolism and inflammation. The role of PPAR-γ in the pathogenesis of NAFLD is gradually being recognized. Here, we outline the involvement of PPAR-γ in the pathogenesis of NAFLD through adipogenesis, insulin resistance, inflammation, oxidative stress, endoplasmic reticulum stress, and fibrosis. In addition, the evidence for PPAR-γ- targeted therapy for NAFLD are summarized. Altogether, PPAR-γ is a promising therapeutic target for NAFLD, and the development of drugs that can balance the beneficial and undesirable effects of PPAR-γ will bring new light to NAFLD patients.

The Effects of Probiotics on Small Intestinal Microbiota Composition, Inflammatory Cytokines and Intestinal Permeability in Patients with Non-Alcoholic Fatty Liver Disease

The prevalence of non-alcoholic fatty liver disease (NAFLD) has soared globally. As our understanding of the disease grows, the role of the gut-liver axis (GLA) in NAFLD pathophysiology becomes more apparent. Hence, we focused mainly on the small intestinal area to explore the role of GLA. We looked at how multi-strain probiotics (MCP^® BCMC^® strains) containing six different Lactobacillus and Bifidobacterium species affected the small intestinal gut microbiota, inflammatory cytokines, and permeability in NAFLD patients. After six months of supplementation, biochemical blood analysis did not show any discernible alterations in either group. Five predominant phyla known as Actinobacteria, Proteobacteria, Firmicutes, Bacteroidota and Fusobacteria were found in NAFLD patients. The probiotics group demonstrated a significant cluster formation of microbiota composition through beta-diversity analysis (p < 0.05). This group significantly reduced three unclassifiable species: unclassified_Proteobacteria, unclassified_Streptococcus, and unclassified_Stenotrophomonas. In contrast, the placebo group showed a significant increase in Prevotella_melaninogenica and Rothia_mucilaginosa, which were classified as pathogens. Real-time quantitative PCR analysis of small intestinal mucosal inflammatory cytokines revealed a significant decrease in IFN-γ (-7.9 ± 0.44, p < 0.0001) and TNF-α (-0.96 ± 0.25, p < 0.0033) in the probiotics group but an increase in IL-6 (12.79 ± 2.24, p < 0.0001). In terms of small intestinal permeability analysis, the probiotics group, unfortunately, did not show any positive changes through ELISA analysis. Both probiotics and placebo groups exhibited a significant increase in the level of circulating zonulin (probiotics: 107.6 ng/mL ± 124.7, p = 0.005 vs. placebo: 106.9 ng/mL ± 101.3, p = 0.0002) and a significant decrease in circulating zonula occluden-1 (ZO-1) (probiotics: -34.51 ng/mL ± 18.38, p < 0.0001 vs. placebo: -33.34 ng/mL ± 16.62, p = 0.0001). The consumption of Lactobacillus and Bifidobacterium suggested the presence of a well-balanced gut microbiota composition. Probiotic supplementation improves dysbiosis in NAFLD patients. This eventually stabilised the expression of inflammatory cytokines and mucosal immune function. To summarise, more research on probiotic supplementation as a supplement to a healthy diet and lifestyle is required to address NAFLD and its underlying causes.

Unraveling the Potential Role of Tecomella undulata in Experimental NASH

The pathophysiology of nonalcoholic steatohepatitis (NASH) is complex, owing to its diverse pathological drivers and, until recently, there were no approved drugs for this disease. Tecomella is a popular herbal medicine used to treat hepatosplenomegaly, hepatitis, and obesity. However, the potential role of Tecomella undulata in NASH has not yet been scientifically investigated. The administration of Tecomella undulata via oral gavage lowered body weight, insulin resistance, alanine transaminase (ALT), aspartate transaminase (AST), triglycerides, and total cholesterol in western diet sugar water (WDSW) fed mice but had no effect on chow diet normal water (CDNW) fed mice. Tecomella undulata improved steatosis, lobular inflammation, and hepatocyte ballooning and resolved NASH in WDSW mice. Furthermore, Tecomella undulata also alleviated the WDSW-induced Endoplasmic Reticulum stress and oxidative stress, enhanced antioxidant status, and thus reduced inflammation in the treated mice. Of note, these effects were comparable to saroglitazar, the approved drug used to treat human NASH and the positive control used in the study. Thus, our findings indicate the potential of Tecomella undulata to ameliorate WDSW-induced steatohepatitis, and these preclinical data provide a strong rationale for assessing Tecomella undulata for the treatment of NASH.

Role of ceramides in diabetic foot ulcers (Review)

Diabetes mellitus (DM) is a metabolic disorder, which if not managed properly, can lead to serious health problems over time and impose significant financial burden on the patient, their family and society as a whole. The study of this disease and the underlying biological mechanism is gaining momentum. Multiple pieces of conclusive evidence show that ceramides are involved in the occurrence and development of diabetes. The present review focuses on the function of ceramides, a type of sphingolipid signaling molecule, to provide a brief description of ceramides and their metabolism, discuss the significant roles of ceramides in the healthy skin barrier, and speculate on the potential involvement of ceramides in the pathogenesis and development of diabetic foot ulcers (DFUs). Understanding these aspects of this disease more thoroughly is crucial to establish how ceramides contribute to the etiology of diabetic foot infections and identify possible therapeutic targets for the treatment of DFUs.

Recent updates on targeting the molecular mediators of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming the most common disease worldwide in an era of rapid economic growth. NAFLD is a multifactorial disease, involving multiple genetic, metabolic, and environmental factors, and is closely associated with metabolic syndrome, obesity, and cardiovascular disease. NAFLD can be classified into nonalcoholic fatty liver disease (NAFL) and nonalcoholic steatohepatitis (NASH), which can both progress to cirrhosis and even hepatocellular carcinoma (HCC). Due to the enormous burden of NAFLD and its complications, no FDA-approved drugs for the treatment of NAFLD are on the market, and therapeutic targets and drug therapies are being actively investigated. In view of the various pathological mechanisms of NAFLD, numbers of preclinical studies and clinical trials have made rapid progress. This review mainly summarizes the most recently characterized mechanisms and therapeutic targets in each mechanism of NAFLD, focusing on the mechanism and application potential.

Saroglitazar, a dual PPAR-α/γ agonist, alleviates LPS-induced hepatic and renal injury in rats

BACKGROUND

Lipopolysaccharide (LPS), an endotoxin within gram-negative bacteria, is associated with systemic acute inflammatory response after invading living tissues and results in sepsis. The liver and kidney are both major target organs in sepsis. Septic acute hepatic-renal injury is a serious clinical condition with high risk of morbidity and mortality. Nevertheless, effective treatment is still lacking.

AIM

This study highlights saroglitazar (SAR), a dual PPAR-α/γ agonist, as a proposed prophylactic drug against LPS-induced hepatic-renal injury.

MAIN METHODS

Rats were pretreated with SAR (2 and 4 mg/kg/day) for 15 days, while sepsis was induced by LPS injection (10 mg/kg) on day 15 one hour following SAR oral administration.

KEY FINDINGS

SAR pretreatment could successfully mitigate LPS-induced hepatic-renal injury, evidenced by enhancement of renal and hepatic functions and a decrease of tissue pathological injury. Meanwhile, SAR alleviated LPS-induced oxidative stress; it reduced malondialdehyde (MDA) levels and ameliorated decreased levels of superoxide dismutase (SOD) and glutathione (GSH). LPS-induced elevations in hepatic and renal nuclear factor-kappa B (NF-κB), phosphorylated inhibitor of kappa B alpha (p-IκBα), interferon-beta (IFN-β), and hepatic high mobility group box-1 (HMGB-1) contents were significantly attenuated in SAR-treated groups. SAR showed an advantageous impact against LPS-induced activation of non-canonical inflammasome and pyroptosis via a significant reduction in cysteinyl aspartate-specific proteinase-11 (Caspase-11) and gasdermin D (GSDMD) expressions. Moreover, Nucleotide-Binding Oligomerization Domain (NOD)-Like Receptor Protein 3 (NLRP3) inflammasome activation with concomitant expression and activation of caspase-1 and release of interleukin-1beta (IL-1β) were considerably diminished following SAR pretreatment.

SIGNIFICANCE

SAR could be considered a prophylactic anti-inflammatory antioxidant drug against LPS-induced liver and kidney injury.

RGS7-ATF3-Tip60 Complex Promotes Hepatic Steatosis and Fibrosis by Directly Inducing TNFα

Aims: The pathophysiological mechanism(s) underlying non-alcoholic fatty liver disease (NAFLD) have yet to be fully delineated and only a single drug, peroxisome proliferator-activated receptor (PPAR) α/γ agonist saroglitazar, has been approved. Here, we sought to investigate the role of Regulator of G Protein Signaling 7 (RGS7) in hyperlipidemia-dependent hepatic dysfunction. Results: RGS7 is elevated in the livers of NAFLD patients, particularly those with severe hepatic damage, pronounced insulin resistance, and high inflammation. In the liver, RGS7 forms a unique complex with transcription factor ATF3 and histone acetyltransferase Tip60, which is implicated in NAFLD. The removal of domains is necessary for ATF3/Tip60 binding compromises RGS7-dependent reactive oxygen species generation and cell death. Hepatic RGS7 knockdown (KD) prevented ATF3/Tip60 induction, and it provided protection against fibrotic remodeling and inflammation in high-fat diet-fed mice translating to improvements in liver function. Hyperlipidemia-dependent oxidative stress and metabolic dysfunction were largely reversed in RGS7 KD mice. Interestingly, saroglitazar failed to prevent RGS7/ATF3 upregulation but it did partially restore Tip60 levels. RGS7 drives the release of particularly tumor necrosis factor α (TNFα) from isolated hepatocytes, stellate cells and its depletion reverses steatosis, oxidative stress by direct TNFα exposure. Conversely, RGS7 overexpression in the liver is sufficient to trigger oxidative stress in hepatocytes that can be mitigated via TNFα inhibition. Innovation: We discovered a novel non-canonical function for an R7RGS protein, which usually functions to regulate G protein coupled receptor (GPCR) signaling. This is the first demonstration for a functional role of RGS7 outside the retina and central nervous system. Conclusion: RGS7 represents a potential novel target for the amelioration of NAFLD. Antioxid. Redox Signal. 38, 137-159.

Orphan receptor GPR50 attenuates inflammation and insulin signaling in 3T3-L1 preadipocytes

Type 2 diabetes (T2DM) is characterized by insulin secretion deficiencies and systemic insulin resistance (IR) in adipose tissue, skeletal muscle, and the liver. Although the mechanism of T2DM is not yet fully known, inflammation and insulin resistance play a central role in the pathogenesis of T2DM. G protein-coupled receptors (GPCRs) are involved in endocrine and metabolic processes as well as many other physiological processes. GPR50 (G protein-coupled receptor 50) is an orphan GPCR that shares the highest sequence homology with melatonin receptors. The aim of this study was to investigate the effect of GPR50 on inflammation and insulin resistance in 3T3-L1 preadipocytes. GPR50 expression was observed to be significantly increased in the adipose tissue of obese T2DM mice, while GPR50 deficiency increased inflammation in 3T3-L1 cells and induced the phosphorylation of AKT and insulin receptor substrate (IRS) 1. Furthermore, GPR50 knockout in the 3T3-L1 cell line suppressed PPAR-γ expression. These data suggest that GPR50 can attenuate inflammatory levels and regulate insulin signaling in adipocytes. Furthermore, the effects are mediated through the regulation of the IRS1/AKT signaling pathway and PPAR-γ expression.

Diagnostic and therapeutic strategies for non-alcoholic fatty liver disease

The global incidence rate of non-alcoholic fatty liver disease (NAFLD) is approximately 25%. With the global increase in obesity and its associated metabolic syndromes, NAFLD has become an important cause of chronic liver disease in many countries. Despite recent advances in pathogenesis, diagnosis, and therapeutics, there are still challenges in its treatment. In this review, we briefly describe diagnostic methods, therapeutic targets, and drugs related to NAFLD. In particular, we focus on evaluating carbohydrate and lipid metabolism, lipotoxicity, cell death, inflammation, and fibrosis as potential therapeutic targets for NAFLD. We also summarized the clinical research progress in terms of drug development and combination therapy, thereby providing references for NAFLD drug development.

Mouse models of nonalcoholic fatty liver disease (NAFLD): pathomechanisms and pharmacotherapies

The prevalence of non-alcoholic fatty liver disease (NAFLD) increases year by year, and as a consequence, NAFLD has become one of the most prevalent liver diseases worldwide. Unfortunately, no pharmacotherapies for NAFLD have been approved by the United States Food and Drug Administration despite promising pre-clinical benefits; this situation highlights the urgent need to explore new therapeutic targets for NAFLD and for the discovery of effective therapeutic drugs. The mouse is one of the most commonly used models to study human disease and develop novel pharmacotherapies due to its small size, low-cost and ease in genetic engineering. Different mouse models are used to simulate various stages of NAFLD induced by dietary and/or genetic intervention. In this review, we summarize the newly described patho-mechanisms of NAFLD and review the preclinical mouse models of NAFLD (based on the method of induction) and appraises the use of these models in anti-NAFLD drug discovery. This article will provide a useful resource for researchers to select the appropriate model for research based on the research question being addressed.

Molecular mechanisms of metabolic associated fatty liver disease (MAFLD): functional analysis of lipid metabolism pathways

The metabolic-associated fatty liver disease (MAFLD) is a condition of fat accumulation in the liver in combination with metabolic dysfunction in the form of overweight or obesity and insulin resistance. It is also associated with an increased cardiovascular disease risk, including hypertension and atherosclerosis. Hepatic lipid metabolism is regulated by a combination of the uptake and export of fatty acids, de novo lipogenesis, and fat utilization by β-oxidation. When the balance between these pathways is altered, hepatic lipid accumulation commences, and long-term activation of inflammatory and fibrotic pathways can progress to worsen the liver disease. This review discusses the details of the molecular mechanisms regulating hepatic lipids and the emerging therapies targeting these pathways as potential future treatments for MAFLD.

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.

Peroxisome proliferator-activated receptor gamma as a therapeutic target for hepatocellular carcinoma: Experimental and clinical scenarios

Hepatocellular carcinoma (HCC) is the most common type of liver cancer worldwide. Viral hepatitis is a significant risk factor for HCC, although metabolic syndrome and diabetes are more frequently associated with the HCC. With increasing prevalence, there is expected to be > 1 million cases annually by 2025. Therefore, there is an urgent need to establish potential therapeutic targets to cure this disease. Peroxisome-proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcription factor that plays a crucial role in the patho-physiology of HCC. Many synthetic agonists of PPARγ suppress HCC in experimental studies and clinical trials. These synthetic agonists have shown promising results by inducing cell cycle arrest and apoptosis in HCC cells and preventing the invasion and metastasis of HCC. However, some synthetic agonists also pose severe side effects in addition to their therapeutic efficacy. Thus natural PPARγ agonists can be an alternative to exploit this potential target for HCC treatment. In this review, the regulatory role of PPARγ in the pathogenesis of HCC is elucidated. Furthermore, the experimental and clinical scenario of both synthetic and natural PPARγ agonists against HCC is discussed. Most of the available literature advocates PPARγ as a potential therapeutic target for the treatment of HCC.

Antidiabetic Effect of Tamarindus indica and Momordica charantia and Downregulation of TET-1 Gene Expression by Saroglitazar in Glucose Feed Adipocytes and Their Involvement in the Type 2 Diabetes-Associated Inflammation In Vitro

To date, there is no satisfactory and effective therapy available to cure type 2 diabetes mellitus (T2DM). This present work is focused on plant extracts and the effect of saroglitazar and TET genes on oxidative stress and inflammation in vitro adipocytes. Aqueous extracts of Tamarindus indica and Momordica charantia seed have shown potent antidiabetic activity that decreases glucose levels in diabetic adipocytes. After seven and fourteen days, the sugar level in the blood was significantly reduced when plant extracts were supplemented. Lipid profiles including total cholesterol (TC), triglyceride (TGL), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL) showed a highly significant change as expected in adipocytes treated with glucose compared with controlled adipocytes (P < 0.001). Gene expression of catalase, superoxide dismutase (SOD1, SOD2), and glutathione peroxidase (GPx) are changed twice, thrice, and quadruplet, respectively. The level of interleukin-1 (IL1) and tumor necrosis factor-α (TNF-α) was restored but the interleukin-6 (IL6) and ten-eleven-translocation-1 (TET1) were completely knocked down by the use of saroglitazar. In comparison with the diabetic group, this supplementation significantly increased glycogen content and glucose-6-phosphate dehydrogenase activity. In the extract supplemented group, glucose-6-phosphatase, glucose-oxidizing enzyme, and glucose-phosphorylating enzyme activities were significantly reduced. After seven days of extract supplementation, these parameters were not resettled to a controlled level; however, after 14 days of supplementation, all parameters were restored to the control level. In addition to altering gene expression, TET enzymes may contribute to altered adiposity and its metabolic consequences. The purpose of this study is to examine new ideas and approaches for treating obesity, T2DM, and other associated metabolic disorders.

Review article: vascular effects of PPARs in the context of NASH

BACKGROUND

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors known to regulate glucose and fatty acid metabolism, inflammation, endothelial function and fibrosis. PPAR isoforms have been extensively studied in metabolic diseases, including type 2 diabetes and cardiovascular diseases. Recent data extend the key role of PPARs to liver diseases coursing with vascular dysfunction, including nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH).

AIM

This review summarises and discusses the pathobiological role of PPARs in cardiovascular diseases with a special focus on their impact and therapeutic potential in NAFLD and NASH.

RESULTS AND CONCLUSIONS

PPARs may be attractive for the treatment of NASH due to their liver-specific effects but also because of their efficacy in improving cardiovascular outcomes, which may later impact liver disease. Assessment of cardiovascular disease in the context of NASH trials is, therefore, of the utmost importance, both from a safety and efficacy perspective.

Nil-Surin Rice Bran Hydrolysates Improve Lipid Metabolism and Hepatic Steatosis by Regulating Secretion of Adipokines and Expression of Lipid-Metabolism Genes

Overconsumption of a high caloric diet is associated with metabolic disorders and a heightened risk of diabetes mellitus (DM), hepatic steatosis, and cardiovascular complications. The use of functional food has received much attention as a strategy in the prevention and treatment of metabolic disorders. This present study investigated whether Nil-Surin rice bran hydrolysates (NRH) could prevent or ameliorate the progression of metabolic disorders in rats in which insulin resistance (IR) was induced by a high fat-high fructose diet (HFFD). After 10 weeks of the HFFD, the rats showed elevated fasting blood glucose (FBG), impaired glucose tolerance, dysregulation of adipokine secretion, distorted lipid metabolism such as dyslipidemia, and increased intrahepatic fat accumulation. The IR was significantly attenuated by a daily dose of NRH (100 or 300 mg/kg/day). Doses of NRH rectified adipokine dysregulation by increasing serum adiponectin and improving hyperleptinemia. Interestingly, NRH decreased intrahepatic fat accumulation and improved dyslipidemia as shown by decreased levels of hepatic triglyceride (TG) and serum TG, total cholesterol and low-density lipoprotein cholesterol, and increased high-density lipoprotein cholesterol. In addition, a modulation of expression of lipid metabolism genes was observed: NRH prevented upregulation of the lipogenesis genes Srebf1 and Fasn. In addition, NRH enhanced the expression of fatty-acid oxidation genes, as evidenced by an increase of Ppara and Cpt1a when compared with the HFFD control group. The activities of NRH in the modulation of lipid metabolism and rectifying the dysregulation of adipokines may result in a decreased risk of DM and hepatic steatosis. Therefore, NRH may be beneficial in ameliorating metabolic disorders in the HFFD model.

PPAR-Targeted Therapies in the Treatment of Non-Alcoholic Fatty Liver Disease in Diabetic Patients

Peroxisome proliferator-activated receptors (PPAR), ligand-activated transcription factors of the nuclear hormone receptor superfamily, have been identified as key metabolic regulators in the liver, skeletal muscle, and adipose tissue, among others. As a leading cause of liver disease worldwide, non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) cause a significant burden worldwide and therapeutic strategies are needed. This review provides an overview of the evidence on PPAR-targeted treatment of NAFLD and NASH in individuals with type 2 diabetes mellitus. We considered current evidence from clinical trials and observational studies as well as the impact of treatment on comorbid metabolic conditions such as obesity, dyslipidemia, and cardiovascular disease. Future areas of research, such as possible sexually dimorphic effects of PPAR-targeted therapies, are briefly reviewed.

Vinexin β deficiency exacerbates diet-induced obesity, hepatosteatosis, insulin resistance and endoplasmic reticulum stress in mice

Vinexin β is a member of an adaptor protein family. Previous research has elucidated its role in cell adhesion and growth factor signaling. Recently, several studies demonstrated its role in metabolic abnormality, such as obesity and atherosclerosis. In this study, we found that vinexin β-knockout (KO) mice were more obese and gained more obvious visceral fat accumulation than their wildtype (WT) littermates fed with high fat diet (HFD). KO mice also showed more severe hepatosteatosis when compared with the WT control, which was in line with the significant increase of key serum lipids in KO mice. Furthermore, we confirmed the inhibited Akt signaling and exacerbated insulin resistance which resulted in high fasting blood glucose in KO mice. The endoplasmic reticulum stress response was found obviously activated which may mediate the metabolic changes in KO mice. Our studies indicated that vinexin β deficiency promotes the diet-induced metabolic disorders.

Emerging Role of Nuclear Receptors for the Treatment of NAFLD and NASH

Non-alcoholic fatty liver (NAFLD) over the past years has become a metabolic pandemic linked to a collection of metabolic diseases. The nuclear receptors ERRs, REV-ERBs, RORs, FXR, PPARs, and LXR are master regulators of metabolism and liver physiology. The characterization of these nuclear receptors and their biology has promoted the development of synthetic ligands. The possibility of targeting these receptors to treat NAFLD is promising, as several compounds including Cilofexor, thiazolidinediones, and Saroglitazar are currently undergoing clinical trials. This review focuses on the latest development of the pharmacology of these metabolic nuclear receptors and how they may be utilized to treat NAFLD and subsequent comorbidities.

Nuclear Receptors Linking Metabolism, Inflammation, and Fibrosis in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) and its progressive form nonalcoholic steatohepatitis (NASH) comprise a spectrum of chronic liver diseases in the global population that can lead to end-stage liver disease and hepatocellular carcinoma (HCC). NAFLD is closely linked to the metabolic syndrome, and comorbidities such as type 2 diabetes, obesity and insulin resistance aggravate liver disease, while NAFLD promotes cardiovascular risk in affected patients. The pathomechanisms of NAFLD are multifaceted, combining hepatic factors including lipotoxicity, mechanisms of cell death and liver inflammation with extrahepatic factors including metabolic disturbance and dysbiosis. Nuclear receptors (NRs) are a family of ligand-controlled transcription factors that regulate glucose, fat and cholesterol homeostasis and modulate innate immune cell functions, including liver macrophages. In parallel with metabolic derangement in NAFLD, altered NR signaling is frequently observed and might be involved in the pathogenesis. Therapeutically, clinical data indicate that single drug targets thus far have been insufficient for reaching patient-relevant endpoints. Therefore, combinatorial treatment strategies with multiple drug targets or drugs with multiple mechanisms of actions could possibly bring advantages, by providing a more holistic therapeutic approach. In this context, peroxisome proliferator-activated receptors (PPARs) and other NRs are of great interest as they are involved in wide-ranging and multi-organ activities associated with NASH progression or regression. In this review, we summarize recent advances in understanding the pathogenesis of NAFLD, focusing on mechanisms of cell death, immunometabolism and the role of NRs. We outline novel therapeutic strategies and discuss remaining challenges.

A Network Pharmacology Study on the Active Components and Targets of the Radix Ginseng and Radix Bupleuri Herb Pair for Treating Nonalcoholic Fatty Liver Disease

OBJECTIVE

To explore the potential active components and corresponding target herb pairs of Radix Ginseng (Renshen) and Radix Bupleuri (Chaihu) in the treatment of nonalcoholic fatty liver disease (NAFLD) through network pharmacology and in vitro experiments.

METHODS

The active components and potential targets of the herb pair of Renshen and Chaihu were screened through a network database system, and Venn analysis was performed with the obtained NAFLD targets. The intersecting targets were analysed for gene ontology (GO) functions and Kyoto Encyclopedia of Genes and Genome (KEGG) pathways, and a protein-protein interaction (PPI) network was generated. Cytoscape software was used to construct active component-target networks of the Renshen and Chaihu herb pair. Free fatty acids were added to the HepG2 cell line to create high-fat models that were treated with different concentrations of stigmasterol. The effect of stigmasterol on the lipid metabolism in HepG2 cells and PPARγ-knockdown cells was determined by oil red O staining, Nile red staining, and TG level. PPARγ and UCP-1 mRNA, and protein expression levels were detected by qRT-PCR and Western blot analyses, respectively.

RESULTS

Twenty active components obtained from the Renshen and Chaihu herb pair were identified. The herb pair active component-target network showed that both Renshen and Chaihu contained stigmasterol and kaempferol as active components. The PPI network comprised 63 protein nodes. GO enrichment analysis and KEGG pathway enrichment analysis showed that the targets were mainly involved in lipid metabolism. Eight core targets were identified: AKT1, PPARG, MAPK3, TNF, TP53, SIRT1, STAT3, and PPARA. In vitro experiments demonstrated that stigmasterol reduced lipid accumulation and TG levels in HepG2 cells, and the mechanism may have been related to the activation of the PPARγ-UCP-1 signalling pathway.

CONCLUSION

This study preliminarily illustrated the potential components and corresponding core targets of the Renshen and Chaihu herb pair in treating NAFLD. The effect of stigmasterol on the PPARγ-UCP-1 signalling pathway in enhancing lipid metabolism may represent one of the mechanisms of the Renshen and Chaihu herb pair in the treatment of NAFLD. The results provide new evidence and research insights to reveal the roles of Renshen and Chaihu in the management of NAFLD.

The role of exosomal miRNA in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) impacts more than one-third of the population and is linked with other metabolic diseases. The term encompasses a wide spectrum of diseases, from modest steatosis to nonalcoholic steatohepatitis, fibrosis and, ultimately, cirrhosis with the potential for development of hepatocellular carcinoma. Currently, available methods for diagnosing NAFLD are invasive or lack accuracy, and monitoring to determine response to therapeutic interventions is challenging. Exosomes are nano-scaled extracellular vesicles that are secreted by a variety of cells. They convey proteins, mRNA, miRNA, and other bioactive molecules between cells and are involved in an extensive range of biological processes, particularly cell-cell communication. Several reports suggest that exosomes mediate miRNAs and, thus, they have potential clinical utility for diagnosis, prognosis, and therapeutics in liver diseases. In view of the vital role of exosomal microRNA in disease, we here synthesized current knowledge about the biogenesis of exosomal miRNA and exosome-mediated microRNA transfer. We then discuss the potential of exosomal miRNA in diagnosis and therapeutics of NAFLD.

Mechanism by which Eucommia ulmoides leaves Regulate Nonalcoholic fatty liver disease based on system pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Eucommia ulmoides (E. ulmoides) leaves are included in the Chinese Pharmacopoeia, and are traditionally used to treat hypertension, obesity, diabetes, and other diseases. Numerous pharmacological studies have shown that E. ulmoides has a good effect on lowering blood lipids and can improve obesity and nonalcoholic fatty liver.

AIM

To study the mechanism of E. ulmoides leaves in regulating nonalcoholic fatty liver disease by combining prediction and validation.

METHODS

Using network pharmacology, and molecular docking to predict E. ulmoides in regulating the action mechanism and potential active ingredients of nonalcoholic fatty liver, large hole adsorption resin enrichment active sites, in vitro experiments were performed to verify its fat-lowering effect and mechanism.

RESULTS

The major components of E. ulmoides leaves exhibited good combination with lipid metabolism-regulating core proteins, particularly flavonoids. EUL 50 significantly reduced lipid accumulation, and increased PPARγ. Compared with the control group, the autophagy level increased after the administration of EUL 50. PPARγ decreased significantly after the addition of chloroquine (CQ, autophagy inhibitor).

CONCLUSION

The active ingredients in E. ulmoides leaves regulating nonalcoholic fatty liver disease are mainly flavonoids and phenolics. EUL 50 may play a role in lowering lipids by regulating PPARγ expression through inducing autophagy.

Target Deconvolution of Fenofibrate in Nonalcoholic Fatty Liver Disease Using Bioinformatics Analysis

Background

Nonalcoholic fatty liver disease (NAFLD) is a prevalent form of liver damage, affecting ~25% of the global population. NAFLD comprises a spectrum of liver pathologies, from hepatic steatosis to nonalcoholic steatohepatitis (NASH), and may progress to liver fibrosis and cirrhosis. The presence of NAFLD correlates with metabolic disorders such as hyperlipidemia, obesity, blood hypertension, cardiovascular, and insulin resistance. Fenofibrate is an agonist drug for peroxisome proliferator-activated receptor alpha (PPARα), used principally for treatment of hyperlipidemia. However, fenofibrate has recently been investigated in clinical trials for treatment of other metabolic disorders such as diabetes, cardiovascular disease, and NAFLD. The evidence to date indicates that fenofibrate could improve NAFLD. While PPARα is considered to be the main target of fenofibrate, fenofibrate may exert its effect through impact on other genes and pathways thereby alleviating, and possibly reversing, NAFLD. In this study, using bioinformatics tools and gene-drug, gene-diseases databases, we sought to explore possible targets, interactions, and pathways involved in fenofibrate and NAFLD.

Methods

We first determined significant protein interactions with fenofibrate in the STITCH database with high confidence (0.7). Next, we investigated the identified proteins on curated targets in two databases, including the DisGeNET and DISEASES databases, to determine their association with NAFLD. We finally constructed a Venn diagram for these two collections (curated genes-NAFLD and fenofibrate-STITCH) to uncover possible primary targets of fenofibrate. Then, Gene Ontology (GO) and KEGG were analyzed to detect the significantly involved targets in molecular function, biological process, cellular component, and biological pathways. A P value < 0.01 was considered the cut-off criterion. We also estimated the specificity of targets with NAFLD by investigating them in disease-gene associations (STRING) and EnrichR (DisGeNET). Finally, we verified our findings in the scientific literature.

Results

We constructed two collections, one with 80 protein-drug interactions and the other with 95 genes associated with NAFLD. Using the Venn diagram, we identified 11 significant targets including LEP, SIRT1, ADIPOQ, PPARA, SREBF1, LDLR, GSTP1, VLDLR, SCARB1, MMP1, and APOC3 and then evaluated their biological pathways. Based on Gene Ontology, most of the targets are involved in lipid metabolism, and KEGG enrichment pathways showed the PPAR signaling pathway, AMPK signaling pathway, and NAFLD as the most significant pathways. The interrogation of those targets on authentic disease databases showed they were more specific to both steatosis and steatohepatitis liver injury than to any other diseases in these databases. Finally, we identified three significant genes, APOC3, PPARA, and SREBF1, that showed robust drug interaction with fenofibrate.

Conclusion

Fenofibrate may exert its effect directly or indirectly, via modulation of several key targets and pathways, in the treatment of NAFLD.

Analysis of the Sphingolipidome in NAFLD

The relationship between sphingolipid levels and NAFLD pathology has been recognized for some time. Numerous studies using pharmacological and genetic approaches in vitro and in animal models of NAFLD have demonstrated that modifications to sphingolipid metabolism can attenuate various facets of NAFLD pathology. However, a more precise understanding of the role of sphingolipids and NAFLD pathology is essential to creating therapeutics that target this pathway. This chapter touches on the scale and variety of sphingolipid metabolites at play in NAFLD, which vary widely in their chemical structures and biological functions. With advances in liquid chromatography and tandem mass spectrometry approaches, each of thousands of individual sphingolipid species and sphingolipid metabolites can be identified and precisely quantified. These approaches are beginning to reveal specific sub-classes and species of sphingolipids that change in NAFLD, and as such, enzymes that generate them can be identified and potentially serve as therapeutic targets. Advances in lipidomics technology have been, and will continue to be, critical to these gains in our understanding of NAFLD.

Esculin protects against methionine choline-deficient diet-induced non-alcoholic steatohepatitis by regulating the Sirt1/NF-κB p65 pathway

CONTEXT

Esculin, an active coumarin compound, has been demonstrated to exert anti-inflammatory effects. However, its potential role in non-alcoholic steatohepatitis (NASH) remains unclear.

OBJECTIVE

This study explored the hepatoprotective effect and the molecular mechanism of esculin in methionine choline-deficient (MCD) diet-induced NASH.

MATERIALS AND METHODS

Fifty C57BL/6J mice were divided into five groups: control, model, low dosage esculin (oral, 20 mg/kg), high dosage esculin (oral, 40 mg/kg), and silybin (oral, 105 mg/kg). All animals were fed a MCD diet, except those in the control group (control diet), for 6 weeks.

RESULTS

Esculin (20 and 40 mg/kg) inhibited MCD diet-induced hepatic lipid content (triglyceride: 16.95 ± 0.67 and 14.85 ± 0.78 vs. 21.21 ± 1.13 mg/g; total cholesterol: 5.10 ± 0.34 and 4.08 ± 0.47 vs. 7.31 ± 0.58 mg/g), fibrosis, and inflammation (ALT: 379.61 ± 40.30 and 312.72 ± 21.45 vs. 559.51 ± 37.01 U/L; AST: 428.22 ± 34.29 and 328.23 ± 23.21 vs. 579.36 ± 31.93 U/L). In vitro, esculin reduced tumour necrosis factor-α, interleukin-6, fibronectin, and collagen 4A1 levels, but had no effect on lipid levels in HepG2 cells induced by free fatty acid. Esculin increased Sirt1 expression levels and decreased NF-κB acetylation levels in vivo and in vitro. Interfering with Sirt1 expression attenuated the beneficial effect of esculin on inflammatory and fibrotic factor production in HepG2 cells.

CONCLUSIONS

These findings demonstrate that esculin ameliorates MCD diet-induced NASH by regulating the Sirt1/ac-NF-κB signalling pathway. Esculin could thus be employed as a therapy for NASH.

Saroglitazar and Hepano treatment offers protection against high fat high fructose diet induced obesity, insulin resistance and steatosis by modulating various class of hepatic and circulating lipids

Higher global prevalence of non-alcoholic fatty liver disease (NAFLD) is associated with obesity, steatosis, and insulin resistance (IR), and often progresses to steatohepatitis (NASH). Even after more than twenty years of research, there is still no FDA approved therapy for the treatment of fatty liver disease/NASH though, Saroglitazar - a dual PPAR α/γ agonist has been recently approved as a therapeutic option for the fatty liver disease in India. Hepatoprotective Ayurvedic formulations are widely used and are considered safe. In the present study, C57BL/6 male mice on HFHF diet for four weeks were treated with vehicle, Saroglitazar (3 mg/kg/po), and Hepano - a formulation of five herbs (200 mg/kg/po), at the human equivalent therapeutic doses for additional eight weeks. These animals were evaluated after 12 weeks for obesity, body mass index (BMI), systemic insulin resistance, hyperglycaemia, dyslipidaemia, and hepatic lipid accumulation. Differential liquid chromatography-mass spectrometry (LC-MS/MS) based lipidomics analysis demonstrated significant changes in the different class of lipids [phospholipids, sphingolipids, diglycerides and triglycerides (TG)] in HFHF fed group. The protective effects of both Saroglitazar and Hepano were evident against IR, obesity and in the modulation of different class of lipids in the circulation and hepatic tissue. Saroglitazar reduced TG as well as modulated phospholipids levels, while Hepano modulated only phospholipids, ceramides, oxidised lipids, and had no effect on hepatic or circulating TG levels in HFHF fed mice. In addition, in vitro studies using HepG2, THP1 and LX2 cells demonstrated safety of both the test substances where Hepano possess better anti-inflammatory as well as anti-fibrotic potential. Overall, Saroglitazar seems to be more efficacious than Hepano in the regimen used against HFHF induced IR, obesity, and dyslipidaemia.

Ginsenoside Re Improves Inflammation and Fibrosis in Hepatic Tissue by Upregulating PPARγ Expression and Inhibiting Oxidative Stress in db/db Mice

Ginsenoside Re (Re) is the main component of “Zhenyuan Capsule” (ZYC), which was wildly used in clinic in China for adjunctive treatment of coronary heart disease (CHD) and type II diabetes (T2DM). Nonalcoholic fatty liver disease (NAFLD) is one of the most important complications of T2DM, as well as an important risk factor of CHD. The aim of the present study was to investigate the effects of Re on NAFLD in db/db mice, one of the most recognized gene deficient animal models on T2DM. Sixteen db/db mice and sixteen wild-type mice were divided into four groups and orally administered Re or placebo in equal volume. According to the results, Re showed no obvious effect on blood glucose, lipids, or body weight of db/db mice. Histology pictures of hepatic tissue showed that Re did not improve steatosis, too. However, some evidence suggested that hepatic injury in db/db mice was attenuated by Re administering. Collagen deposition and aminotransferase elevation were significantly downregulated in the DB + Re group compared to those in the DB Group. The mechanisms of the protect effects of Re represented in db/db mice with NAFLD might be inhibiting oxidative stress and the reupregulation of peroxisome proliferator-activated receptor γ (pparγ) expression. The results of this study indicated that ZYC might be able to help T2DM patients with NAFLD to control the progress of NAFLD as an alternation of thiazolidinediones, synthetic agonists of PPARγ, whose side effects and adverse events should not be ignored.