Ginsenoside Rc Modulates SIRT6-NRF2 Interaction to Alleviate Alcoholic Liver Disease

Ginseng fermentation solution affects the gut microbiota in zebrafish with alcoholic liver disease via PI3K/Akt pathway

BACKGROUND

Ginsenosides have received increased amounts of attention due to their ability to modulate the intestinal flora, which may subsequently alleviate alcoholic liver disease (ALD). The effects of ginseng fermentation solution (GFS) on the gut microbiota and metabolism in ALD patients have not been explored.

PURPOSE

This research aimed to explore the regulatory effect of GFS on ALD both in vitro and in vivo.

METHOD

This study assessed the anti-ALD efficacy of GFS using an LO2 cell model and a zebrafish model. Untargeted metabolomics was used for differentially abundant metabolite analysis, and high-throughput 16S rRNA sequencing was used to examine the effect of GFS on ALD.

RESULTS

The LO2 cell line experiments demonstrated that GFS effectively mitigated alcohol-induced oxidative stress and reduced apoptosis by upregulating PI3K and Bcl-2 expression and decreasing the levels of malondialdehyde, total cholesterol, and triglycerides. In zebrafish, GFS improved morphological and physiological parameters and diminished oxidative stress-induced ALD. Meanwhile, the results from Western blotting indicated that GFS enhanced the expression of PI3K, Akt, and Bcl-2 proteins while reducing Bax protein expression, thereby ameliorating the ALD model in zebrafish. Metabolomics data revealed significant changes in a total of 46 potential biomarkers. Among them, metabolites such as prostaglandin F2 alpha belong to arachidonic acid metabolism. In addition, GFS also partly reversed the imbalance of gut microbiota composition caused by alcohol. At the genus level, alcohol consumption elevated the presence of Flectobacillus, Curvibacter, among others, and diminished Elizabethkingia within the intestinal microbes of zebrafish. Conversely, GFS reversed these effects, notably enhancing the abundance of Proteobacteria and Archaea. Correlation analyses further indicated a significant negative correlation between prostaglandin F2 alpha, 11,14,15-THETA, Taurocholic acid and Curvibacter.

CONCLUSION

This study highlights a novel mechanism by which GFS modulates anti-ALD activity through the PI3K/Akt signalling pathway by influencing the intestinal flora-metabolite axis. These results indicate the potential of GFS as a functional food for ALD treatment via modulation of the gut flora.

Pogostone attenuated high-fat diet-induced nonalcoholic fatty liver disease in mice through inhibition of NLRP3 inflammasome signaling

Inhibition of inflammasome activation is a potential therapeutic strategy for treating nonalcoholic fatty liver disease (NAFLD). Pogostone (PO), an active ingredient in Pogostemon cablin, exhibits various pharmacological properties, including anti-inflammation. However, there are no reports of the hepatoprotective effects of PO in NAFLD induced by a high-fat diet (HFD). Molecular biology methods and molecular docking analysis were used to determine the therapeutic effects and mechanisms of PO in NAFLD in vitro and in vivo. Results showed that in vitro, PO reduced lipid deposition, accelerated fatty acid oxidation (FAO), and inhibited the inflammatory response by elevating mRNA expression of FAO genes and decreasing mRNA expression of proinflammatory genes such as NLRP3. In vivo, PO significantly reduced body weight and liver fat deposition and lowered the generation of inflammatory factors, thereby ameliorating liver fibrosis and liver injury. The hepatoprotective effect of PO against HFD was largely impaired in NLRP3-/- mice. Molecular docking experiments demonstrated a strong interaction between PO and NLRP3. In conclusion, PO decreased fat deposition and the inflammatory response by inhibiting NLRP3 expression, resulting in the alleviation of NAFLD. Our study suggests that PO may be a promising treatment for NAFLD.

Vialinin A alleviates oxidative stress and neuronal injuries after ischaemic stroke by accelerating Keap1 degradation through inhibiting USP4-mediated deubiquitination

BACKGROUND

Oxidative stress is known as a hallmark of cerebral ischaemia‒reperfusion injury and it exacerbates the pathologic progression of ischaemic brain damage. Vialinin A, derived from a Chinese edible mushroom, possesses multiple pharmacological activities in cancer, Kawasaki disease, asthma and pathological scarring. Notably, vialinin A is an inhibitor of ubiquitin-specific peptidase 4 (USP4) that shows anti-inflammatory and antioxidative properties. However, the precise effect of vialinin A in ischaemic stroke, as well as its underlying mechanisms, remains largely unexplored.

PURPOSE

The present research focuses on the impacts of vialinin A on oxidative stress and explores the underlying mechanisms involved while also examining its potentiality as a therapeutic candidate for ischaemic stroke.

METHODS

Mouse ischaemic stroke was conducted by MCAO surgery. Vialinin A was administered via lateral ventricular injection at a dose of 2 mg/kg after reperfusion. Subsequent experiments were meticulously conducted at the appropriate time points. Stroke outcomes were evaluated by TTC staining, neurological score, Nissl staining and behavioural analysis. Co-IP assays were operated to examine the protein-protein interactions. Immunoblot analysis, qRT-PCR, and luciferase reporter assays were conducted to further investigate its underlying mechanisms.

RESULTS

In this study, we initially showed that administration of vialinin A alleviated cerebral ischaemia‒reperfusion injury-induced neurological deficits and neuronal apoptosis. Furthermore, vialinin A, which is an antioxidant, reduced oxidative stress injury, promoted the activation of the Keap1-Nrf2-ARE signaling pathway and increased the protein degradation of Keap1. The substantial neuroprotective effects of vialinin A against ischaemic stroke were compromised by the overexpression of USP4. Mechanistically, vialinin A inhibited the deubiquitinating enzymatic activity of USP4, leading to enhanced ubiquitination of Keap1 and subsequently promoting its degradation. This cascade caused the activation of Nrf2-dependent antioxidant response, culminating in a reduction of neuronal apoptosis and the amelioration of neurological dysfunction following ischaemic stroke.

CONCLUSIONS

This study demonstrates that inhibition of USP4 to activate Keap1-Nrf2-ARE signaling pathway may represent a mechanism by which vialinin A conferred protection against cerebral ischaemia‒reperfusion injury and sheds light on its promising prospects as a therapeutic intervention for ischaemic stroke.

Integrated analysis of metabolomic and transcriptomic profiling reveals the effect of Atractylodes oil on Spleen Yang Deficiency Syndrome in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Spleen Yang Deficiency Syndrome (SYDS), which is a syndrome commonly treated with Traditional Chinese Medicine (TCM), manifests as overall metabolic dysfunction caused mainly by digestive system disorders. Atractylodes lancea (Thunb.) DC. (AL) is a widely used traditional herb with the efficacy of eliminate dampness and strengthen the spleen, Atractylodes oil (AO) is a medicinal component of AL and can be used to treat various gastrointestinal disorders. However, its effects on SYDS and underlying mechanisms have not been clarified to date.

AIM OF THE STUDY

The present study aimed to investigate the efficacy of AO in the improvement of the symptoms of SYDS in rat and the underlying mechanism by integrating transcriptomics, and metabolomics.

MATERIALS AND METHODS

The SYDS rats induced by reserpine were treated with AO. The protective effect of AO on SYDS rats was evaluated by serum biochemical detection, histopathological analyses. Enzyme-linked immunosorbent assay (ELISA), colorimetric assay and immunofluorescence (IF) were performed to determine the levels of relevant indicators of mitochondrial function and energy metabolism in the liver. Liver metabolites and transcript levels were assessed by non-targeted metabolomics and transcriptomics to analyze potential molecular mechanisms and targets. The expression of the corresponding proteins was verified using Western blotting.

RESULTS

AO not only regulated the digestion, absorption function and oxidative stress status of SYDS rats, but also improved mitochondrial function and alleviated energy metabolism disorders in SYDS rats. Metabolomic and transcriptomic analyses demonstrated that AO regulation is mainly exerted in amino acid metabolism, unsaturated fatty acid metabolism, TCA cycle as well as PPAR and AMPK signaling pathways. In addition, The AMPK signaling pathway was verified and AO promoted AMPK phosphorylation and the expression of SIRT1, PGC-1α, and PPARα in SYDS rats.

CONCLUSIONS

The therapeutic effect of AO on SYDS is potentially attributable to activation of the AMPK/SIRT1/PGC-1α signaling pathway, which enhances transport and regulation of energy metabolism.

Sirt6 promotes DNA damage repair in osteoarthritis chondrocytes by activating the Keap1/Nrf2/HO-1 signaling pathway

The aim of this study was to explore the effect and mechanism of Sirt6 on DNA damage repair in OA chondrocytes. Cartilage tissues were collected from OA patients with knee arthroplasty and traumatic amputation patients without OA. Besides, 7-week-old male C57BL/6 mice were randomly divided into Control and OA groups; CHON-001 cells of corresponding groups were treated with 10 ng/ml interleukin (IL)-1β, respectively. Subsequently, Sirt6 or siNrf2 was over-expressed in CHON-001 cells to observe the effect of Sirt6 on DNA damage and senescence of chondrocytes by IL-1β through the nuclear factor E2-related factor 2 (Nrf2) signaling pathway. The expression level of Sirt6 in human and mouse OA cartilage tissues was significantly decreased. However, 24 h of treatment with IL-1β significantly decreased the expression of Sirt6 in chondrocytes, induced DNA damage, and promoted cellular senescence. In addition, over-expression of Sirt6 promoted DNA damage repair and inhibited cellular senescence in IL-1β-induced chondrocytes. Moreover, the overexpression of Sirt6 activated the Keap1/Nrf2/HO-1 signaling pathway in chondrocytes, while knockdown of Nrf2 expression inhibited the DNA damage repair and anti-senescence effects of Sirt6 on IL-1β-treated chondrocytes. Sirt6 may reduce DNA damage and cellular senescence in OA chondrocytes induced by IL-1β through activating the Keap1/Nrf2/HO-1 signaling pathway.

Ginsenoside Rc: A potential intervention agent for metabolic syndrome

Ginsenoside Rc, a dammarane-type tetracyclic triterpenoid saponin primarily derived from Panax ginseng, has garnered significant attention due to its diverse pharmacological properties. This review outlined the sources, putative biosynthetic pathways, extraction, and quantification techniques, as well as the pharmacokinetic properties of ginsenoside Rc. Furthermore, this study explored the pharmacological effects of ginsenoside Rc against metabolic syndrome (MetS) across various phenotypes including obesity, diabetes, atherosclerosis, non-alcoholic fatty liver disease, and osteoarthritis. It also highlighted the impact of ginsenoside Rc on multiple associated signaling molecules. In conclusion, the anti-MetS effect of ginsenoside Rc is characterized by its influence on multiple organs, multiple targets, and multiple ways. Although clinical investigations regarding the effects of ginsenoside Rc on MetS are limited, its proven safety and tolerability suggest its potential as an effective treatment option.

Regulation of Nur77-TLR4/MyD88 signaling pathway is required for Ginsenoside Rc ameliorates hepatic fibrosis regression by deactivating hepatic stellate cells

HSCs (hepatic stellate cells) contribute to the excessive extracellular matrix (ECM) deposition plays a key role in the progression of hepatic fibrosis. The present study focused on the hepatoprotective effect of Ginsenoside Rc (Rc), one of the protopanaxadiol type ginsenoside, which has contributed to reverse activated HSCs to improve hepatic fibrosis via regulating Nur77-TLR4/MyD88 signaling pathway. We established the hepatic fibrosis model by intraperitoneal injection of carbon tetrachloride (CCl4). And HSCs were stimulated with TGF-β, followed by silencing of Nur77, and then incubated in Rc. Rc significantly alleviated histopathological changes, reduced serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Rc could upregulate the Nur77 and downregulate fibrosis markers in the liver of mice, including decreasing the expressions of α-SMA, Collagen-I, the ratio of TIMP-1/MMP-13. Rc significantly increased the expression of Nur77 and suppressed the production of ECM in HSCs. Rc inhibited TLR4 signaling pathway, consequently reversing the inflammatory response, including the production of MyD88, IRAK1, IRAK4 and IL-23. When Nur77 was knocked in TGF-β-stimulated HSCs, TLR4 and α-SMA production were increased. Rc suppressed these activatory effects in Nur77 knockdown HSCs. Rc reduced inflammatory reaction by regulating the Nur77-TLR4 signaling pathway while suppressing the fibrogenesis suggesting, underscoring a promising approach of Rc for the treatment in hepatic fibrosis. Targeting Nur77-TLR4 signaling in HSCs would be the potential strategy for Rc against hepatic fibrosis.

Hepatic Clstn3 Ameliorates Lipid Metabolism Disorders in High Fat Diet-Induced NAFLD through Activation of FXR

Non-alcoholic fatty liver disease (NAFLD) has become serious liver disease all over the world. At present, NAFLD caused by high calorie and fat diet is increasing. Calsyntenin-3 (Clstn3) is a transmembrane protein that has recently been found to participate in lipid energy metabolism. But whether Clstn3 affects NAFLD lipid metabolism has not been analyzed. We stimulate the mice primary hepatocytes (MPHs) with oleic acid and palmitic acid (OA&PA) to establish a cell model. Then, potential targets, including Clstn3 gene, were validated for improving lipid metabolism disorder in NAFLD model mice (HFD and db/db) by silencing and overexpressing hepatic Clstn3. Moreover, the effects of Clstn3 on lipid homeostasis were determined by functional determination, triglyceride (TG) levels, total cholesterol (TC) levels, ELISA, and qRT-PCR detection. Our results displayed that Clstn3 was decreased in the NAFLD mice model. Also, overexpression of Clstn3 improved lipid metabolism disorders, gluconeogenesis, and energy homeostasis and reduced liver injury, inflammation, and oxidative stress injury. However, opposite results were obtained in Clstn3-silencing mice, suggesting that the Clstn3 gene is closely related to lipid metabolism disorder in NAFLD. RNAseq expression demonstrated that Farnesoid X Receptor (FXR) expression was increased after overexpression of Clstn3. Clstn3 supplementation in FXRKO mice can improve the dysfunction caused by insufficient FXR, suggesting that Clstn3 can improve the NAFLD lipid metabolism disorder to some extent through FXR, which may provide a new method for the treatment of NAFLD.

Research Progress on the Anti-Aging Potential of the Active Components of Ginseng

Aging is a cellular state characterized by a permanent cessation of cell division and evasion of apoptosis. DNA damage, metabolic dysfunction, telomere damage, and mitochondrial dysfunction are the main factors associated with senescence. Aging increases β-galactosidase activity, enhances cell spreading, and induces Lamin B1 loss, which further accelerate the aging process. It is associated with a variety of diseases, such as Alzheimer's disease, Parkinson's, type 2 diabetes, and chronic inflammation. Ginseng is a traditional Chinese medicine with anti-aging effects. The active components of ginseng, including saponins, polysaccharides, and active peptides, have antioxidant, anti-apoptotic, neuroprotective, and age-delaying effects. DNA damage is the main factor associated with aging, and the mechanism through which the active ingredients of ginseng reduce DNA damage and delay aging has not been comprehensively described. This review focuses on the anti-aging mechanisms of the active ingredients of ginseng. Furthermore, it broadens the scope of ideas for further research on natural products and aging.

Ginsenosides for therapeutically targeting inflammation through modulation of oxidative stress

Ginsenosides are steroid glycosides derived from ginseng plants such as Panax ginseng, Panax quinquefolium, and Panax notoginseng. Advances in recent studies have identified numerous physiological functions of each type of ginsenoside, i.e., immunomodulatory, antioxidative, and anti-inflammatory functions, in the context of inflammatory diseases. Accumulating evidence has revealed the molecular mechanisms by which the single or combined ginsenoside(s) exhibit anti-inflammatory effects, although it remains largely unclear. It is well known that excessive production of reactive oxygen species (ROS) is associated with pathological inflammation and cell death in a variety of cells, and that inhibition of ROS generation ameliorates the local and systemic inflammatory responses. The mechanisms by which ginsenosides attenuate inflammation are largely unknown; however, targeting ROS is suggested as one of the crucial mechanisms for the ginsenosides to control the pathological inflammation in the immune and non-immune cells. This review will summarize the latest progress in ginsenoside studies, particularly in the context of antioxidant mechanisms for its anti-inflammatory effects. A better understanding of the distinct types and the combined action of ginsenosides will pave the way for developing potential preventive and therapeutic modalities in treating various inflammation-related diseases.

Exploring the pathogenesis of colorectal carcinoma complicated with hepatocellular carcinoma via microarray data analysis

Background: Despite the increasing number of research endeavors dedicated to investigating the relationship between colorectal carcinoma (CRC) and hepatocellular carcinoma (HCC), the underlying pathogenic mechanism remains largely elusive. The aim of this study is to shed light on the molecular mechanism involved in the development of this comorbidity. Methods: The gene expression profiles of CRC (GSE90627) and HCC (GSE45267) were downloaded from the Gene Expression Omnibus (GEO) database. After identifying the common differentially expressed genes (DEGs) of psoriasis and atherosclerosis, three kinds of analyses were performed, namely, functional annotation, protein-protein interaction (PPI) network and module construction, and hub gene identification, survival analysis and co-expression analysis. Results: A total of 150 common downregulated differentially expressed genes and 148 upregulated differentially expressed genes were selected for subsequent analyses. The significance of chemokines and cytokines in the pathogenesis of these two ailments is underscored by functional analysis. Seven gene modules that were closely connected were identified. Moreover, the lipopolysaccharide-mediated signaling pathway is intricately linked to the development of both diseases. Finally, 10 important hub genes were identified using cytoHubba, including CDK1, KIF11, CDC20, CCNA2, TOP2A, CCNB1, NUSAP1, BUB1B, ASPM, and MAD2L1. Conclusion: Our study reveals the common pathogenesis of colorectal carcinoma and hepatocellular carcinoma. These common pathways and hub genes may provide new ideas for further mechanism research.

Leonurine alleviates acetaminophen-induced acute liver injury by regulating the PI3K/AKT signaling pathway in mice

Leonurine (Leo) is a natural alkaloid isolated from the herb Leonurus japonicus Houtt. (Leonuri) that has been shown to inhibit oxidative stress and inflammation. However, the role and mechanism of Leo in acetaminophen (APAP)-induced acute liver injury (ALI) remain unknown. In this study, we investigated the protective effect of Leo against APAP-induced ALI and elucidated the molecular mechanism. Here, we showed that the damage to mouse primary hepatocytes (MPHs) induced by APAP was attenuated by treatment with Leo, which promoted proliferation and inhibited oxidative stress injury, and Leo significantly improved APAP-induced ALI in mice. Leo could protect against APAP-induced ALI by reducing serum aspartate aminotransferase (AST) and alanine transaminase (ALT) levels, hepatic histopathological damage, liver cell necrosis, inflammation, and oxidative stress-induced damage in vivo and in vitro. Moreover, the results indicated that Leo relieved APAP-induced liver cell necrosis by reducing the expression of Bax and cleaved caspase-3 and increasing Bcl-2 expression. Leo alleviated APAP-induced oxidative stress-induced damage by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, which facilitated Nrf2 nuclear translocation and upregulated oxidative stress-related protein expression in liver tissues. Moreover, the results suggested that APAP-induced inflammation in the liver was suppressed by Leo by suppressing the Toll-like receptor 4 (TLR4) and NLR family pyrin domain containing 3 (NLRP3) pathways. In addition, Leo facilitated the activation of the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway in the liver tissue of ALI mice. Network pharmacology, molecular docking, and western blotting showed that PI3K was a potential target of Leo in the treatment of ALI. Molecular docking and cellular thermal shift assay (CETSA) indicated that Leo could stably bind to the PI3K protein. In conclusion, Leo attenuated ALI, and reversed liver cell necrosis, the inflammatory response and oxidative stress-induced damage by regulating the PI3K/AKT signaling pathway.

A Meta-Analysis of Preclinical Studies to Investigate the Effect of Panax ginseng on Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) has become a major global concern, but the development of effective drugs remains a challenge despite numerous preclinical and clinical pieces of research on the effects of natural compounds. To address this, a meta-analysis was conducted on the efficacy of Panax ginseng for ALD based on preclinical studies. We identified 18 relevant studies from PubMed, Web of Science, and Cochrane Library database and evaluated their methodological quality using the Systematic Review Centre for Laboratory animal Experimentation tool. We analyzed the data using I2, p-values, and fixed effects models to assess overall efficacy and heterogeneity. The results of the meta-analysis suggested that Panax ginseng treatment is effective in reducing the levels of inflammatory markers associated with hepatic injury caused by ALD in animal experiments. Additionally, the administration of Panax ginseng was found to down-regulate inflammatory cytokines and attenuate lipid metabolism in ALD. Moreover, Panax ginseng markedly improved the antioxidant systems in ALD. Therefore, we concluded that Panax ginseng has the potential to be a promising therapeutic agent for ALD. Further research is needed to confirm these findings and to determine the optimal dosage and duration of treatment for patients with ALD.

Effects of various interventions on non-alcoholic fatty liver disease (NAFLD): A systematic review and network meta-analysis

Background: With the increasing prevalence of obesity and metabolic syndrome, the incidence of non-alcoholic fatty liver disease (NAFLD) is also increasing. In the next decade, NAFLD may become the main cause of liver transplantation. Therefore, the choice of treatment plan is particularly important. The purpose of this study was to compare several interventions in the treatment of NAFLD to provide some reference for clinicians in selecting treatment methods.

Methods: We searched Public Medicine (PubMed), Medline, Excerpta Medica Database (Embase), and Cochrane Library from January 2013 to January 2023 to identify randomized controlled trials (RCTs) published in English. The network meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Forty-three studies accounting for a total of 2,969 patients were included, and alanine aminotransferase (ALT), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL) were selected as outcome measures for analysis and comparison.

Results: We evaluated the results of drug, diet, and lifestyle interventions between the intervention and control groups. Curcumin (CUN) and probiotics (PTC) were selected for medication, the Mediterranean diet (MDED) was selected for special diet (SPD), and various kinds of exercise and lifestyle advice were selected for lifestyle interventions (LFT). The SUCRA was used to rank interventions according to the effect on ALT indicators (SUCRA: PTC 80.3%, SPD 65.2%, LFT 61.4%, PLB 32.8%, CUN 10.2%), TC indicators (SUCRA: PTC 89.4%, SPD 64%, CUN 34%, LFT 36.6%, PLB 17%), and LDL indicators (SUCRA: PTC 84.2%, CUN 69.5%, LFT 51.7%, PLB 30.1%, SPD 14.5%). The pairwise meta-analysis results showed that MDED was significantly better than NT in improving ALT [SMD 1.99, 95% CI (0.38, 3.60)]. In terms of improving TC and LDL, ATS was significantly better than NT [SMD 0.19, 95% CI (0.03, 0.36)] [SMD 0.18, 95% CI (0.01, 0.35)].

Conclusion: Our study showed that PTC is most likely to be the most effective treatment for improving NAFLD indicators. Professional advice on diet or exercise was more effective in treating NAFLD than no intervention.

Sirtuin 6-A Key Regulator of Hepatic Lipid Metabolism and Liver Health

Sirtuin 6 (SIRT6) is an NAD-dependent deacetylase/deacylase/mono-ADP ribosyltransferase, a member of the sirtuin protein family. SIRT6 has been implicated in hepatic lipid homeostasis and liver health. Hepatic lipogenesis is driven by several master regulators including liver X receptor (LXR), carbohydrate response element binding protein (ChREBP), and sterol regulatory element binding protein 1 (SREBP1). Interestingly, these three transcription factors can be negatively regulated by SIRT6 through direct deacetylation. Fatty acid oxidation is regulated by peroxisome proliferator activated receptor alpha (PPARα) in the liver. SIRT6 can promote fatty acid oxidation by the activation of PPARα or the suppression of miR-122. SIRT6 can also directly modulate acyl-CoA synthetase long chain family member 5 (ACSL5) activity for fatty acid oxidation. SIRT6 also plays a critical role in the regulation of total cholesterol and low-density lipoprotein (LDL)-cholesterol through the regulation of SREBP2 and proprotein convertase subtilisin/kexin type 9 (PCSK9), respectively. Hepatic deficiency of Sirt6 in mice has been shown to cause hepatic steatosis, inflammation, and fibrosis, hallmarks of alcoholic and nonalcoholic steatohepatitis. SIRT6 can dampen hepatic inflammation through the modulation of macrophage polarization from M1 to M2 type. Hepatic stellate cells are a key cell type in hepatic fibrogenesis. SIRT6 plays a strong anti-fibrosis role by the suppression of multiple fibrogenic pathways including the transforming growth factor beta (TGFβ)-SMAD family proteins and Hippo pathways. The role of SIRT6 in liver cancer is quite complicated, as both tumor-suppressive and tumor-promoting activities have been documented in the literature. Overall, SIRT6 has multiple salutary effects on metabolic homeostasis and liver health, and it may serve as a therapeutic target for hepatic metabolic diseases. To date, numerous activators and inhibitors of SIRT6 have been developed for translational research.

ATL I, Acts as a SIRT6 Activator to Alleviate Hepatic Steatosis in Mice via Suppression of NLRP3 Inflammasome Formation

Accumulating evidence has highlighted that sirtuin-6 (SIRT6) plays an important role in hepatic gluconeogenesis and lipogenesis. We aim to investigate the underlying mechanisms and pharmacological interventions of SIRT6 on hepatic steatosis treatment. Herein, our results showed that atractylenolide I (ATL I) activated the deacetylase activity of SIRT6 to promote peroxisome proliferator-activated receptor alpha (PPARα) transcription and translation, while suppressing nuclear factor NF-kappa-B (NFκB)-induced NACHT, LRR, and PYD domains containing protein 3 (NLRP3) inflammasome formation. Together, these decreased the infiltration of F4/80 and CD11B positive macrophages, accompanied by decreased mRNA expression and serum levels of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL6), and interleukin-1 beta (IL1β). Additionally, these changes decreased sterol regulatory element-binding protein-1c (SREBP-1c) expression, while restoring carnitine O-palmitoyltransferase 1a (Cpt1a) expression, to decrease the size of adipocytes and adipose deposition, which, in turn, reversed high-fat diet (HFD)-induced liver weight and body weight accumulation in C57 mice. SIRT6 knockout or hepatic SIRT6 knockout in C57 mice largely abolished the effect of ATL I on ameliorating hepatic steatosis. Taken together, our results suggest that ATL I acts as a promising compound that activates SIRT6/PPARα signaling and attenuates the NLRP3 inflammasome to ameliorate hepatic inflammation and steatosis.