Emerging roles of Sirtuins in alleviating alcoholic liver Disease: A comprehensive review

Alcohol-related liver disease (ALD): current perspectives on pathogenesis, therapeutic strategies, and animal models

Alcohol-related liver disease (ALD) is a major cause of morbidity and mortality worldwide. It encompasses conditions such as fatty liver, alcoholic hepatitis, chronic hepatitis with liver fibrosis or cirrhosis, and hepatocellular carcinoma. Numerous recent studies have demonstrated the critical role of oxidative stress, abnormal lipid metabolism, endoplasmic reticulum stress, various forms of cell death (including apoptosis, necroptosis, and ferroptosis), intestinal microbiota dysbiosis, liver immune response, cell autophagy, and epigenetic abnormalities in the pathogenesis of ALD. Currently, abstinence, corticosteroids, and nutritional therapy are the traditional therapeutic interventions for ALD. Emerging therapies for ALD mainly include the blockade of inflammatory pathways, the promotion of liver regeneration, and the restoration of normal microbiota. Summarizing the advances in animal models of ALD will facilitate a more systematic investigation of the pathogenesis of ALD and the exploration of therapeutic targets. This review summarizes the latest insight into the pathogenesis and molecular mechanisms of ALD, as well as the pros and cons of ALD rodent models, providing a basis for further research on therapeutic strategies for ALD.

Dietary supplementation of pterostilbene, a major component in small berries, prevents alcohol-induced liver injury associated with lipid accumulation and inflammation

Pterostilbene (PTE), a natural stilbene found in small berries, exhibits multiple pharmacological activities, particularly antioxidant and anti-inflammatory activities. This study explores the dietary supplementation of PTE to ameliorate acute and chronic alcohol-associated liver disease (ALD). C57BL/6 mice were administrated with PTE and subjected to acute or chronic alcohol stimulation. They were intragastrically administered with alcohol (5 g kg-1, 3 times per 24 h) to induce acute alcohol liver injury or fed a Lieber-DeCarli liquid diet containing 5% ethanol for 4 weeks and a single binge to induce chronic alcoholic liver injury. In the acute ethanol model, PTE decreased the serum transaminase and triglyceride (TG) levels and ameliorated lipid droplet accumulation. PTE ameliorated acute ethanol-induced hepatic steatosis by inhibiting the expression of SREBP1 and its target genes and up-regulating PPARα expression. PTE could reverse the inflammatory response by inhibiting NLRP3 activation, inflammatory factor secretion, and macrophage recruitment caused by acute ethanol exposure. PTE could synergistically activate the SIRT1-AMPK and LXR/FXR axis in mice with acute ethanol exposure. In the chronic-binge ethanol feeding model, PTE also decreased serum transaminase and TG levels and ameliorated hepatocellular ballooning, macrovesicular steatosis, lipid accumulation and inflammation. Chronic-binge ethanol feeding could induce extracellular matrix dysfunction with an increase in α-SMA, collagen I and TIMP-1 expression, which was decreased by PTE. PTE increased SIRT1 expression and AMPK phosphorylation and activated the LXRs/FXR axis, which could be reduced by chronic-binge ethanol feeding. PTE could prevent liver injury caused by alcohol regardless of acute or chronic exposure. These results suggest that PTE can be utilized as a dietary health supplement to avoid ALD and promote health and quality of life.

Hepatic Extracellular Matrix and Its Role in the Regulation of Liver Phenotype

The hepatic extracellular matrix (ECM) is most accurately depicted as a dynamic compartment that comprises a diverse range of players that work bidirectionally with hepatic cells to regulate overall homeostasis. Although the classic meaning of the ECM referred to only proteins directly involved in generating the ECM structure, such as collagens, proteoglycans, and glycoproteins, the definition of the ECM is now broader and includes all components associated with this compartment. The ECM is critical in mediating phenotype at the cellular, organ, and even organismal levels. The purpose of this review is to summarize the prevailing mechanisms by which ECM mediates hepatic phenotype and discuss the potential or established role of this compartment in the response to hepatic injury in the context of steatotic liver disease.

HMGB1 as an extracellular pro-inflammatory cytokine: Implications for drug-induced organic damage

Drug-induced organic damage encompasses various intricate mechanisms, wherein HMGB1, a non-histone chromosome-binding protein, assumes a significant role as a pivotal hub gene. The regulatory functions of HMGB1 within the nucleus and extracellular milieu are interlinked. HMGB1 exerts a crucial regulatory influence on key biological processes including cell survival, inflammatory regulation, and immune response. HMGB1 can be released extracellularly from the cell during these processes, where it functions as a pro-inflammation cytokine. HMGB1 interacts with multiple cell membrane receptors, primarily Toll-like receptors (TLRs) and receptor for advanced glycation end products (RAGE), to stimulate immune cells and trigger inflammatory response. The excessive or uncontrolled HMGB1 release leads to heightened inflammatory responses and cellular demise, instigating inflammatory damage or exacerbating inflammation and cellular demise in different diseases. Therefore, a thorough review on the significance of HMGB1 in drug-induced organic damage is highly important for the advancement of pharmaceuticals, ensuring their effectiveness and safety in treating inflammation as well as immune-related diseases. In this review, we initially outline the characteristics and functions of HMGB1, emphasizing their relevance in disease pathology. Then, we comprehensively summarize the prospect of HMGB1 as a promising therapeutic target for treating drug-induced toxicity. Lastly, we discuss major challenges and propose potential avenues for advancing the development of HMGB1-based therapeutics.

What are the common downstream molecular events between alcoholic and nonalcoholic fatty liver?

Liver fat storage, also called hepatic steatosis, is increasingly common and represents a very frequent diagnosis in the medical field. Excess fat is not without consequences. In fact, hepatic steatosis contributes to the progression toward liver fibrosis. There are two main types of fatty liver disease, alcoholic fatty liver disease (AFLD) and nonalcoholic fatty liver disease (NAFLD). Although AFLD and NAFLD are similar in their initial morphological features, both conditions involve the same evolutive forms. Moreover, there are various common mechanisms underlying both diseases, including alcoholic liver disease and NAFLD, which are commonalities. In this Review, the authors explore similar downstream signaling events involved in the onset and progression of the two entities but not completely different entities, predominantly focusing on the gut microbiome. Downstream molecular events, such as the roles of sirtuins, cytokeratins, adipokines and others, should be considered. Finally, to complete the feature, some new tendencies in the therapeutic approach are presented.

Anti-miR-873-5p improves alcohol-related liver disease by enhancing hepatic deacetylation via SIRT1

Background & Aims

Current therapies for the treatment of alcohol-related liver disease (ALD) have proven largely ineffective. Patients relapse and the disease progresses even after liver transplantation. Altered epigenetic mechanisms are characteristic of alcohol metabolism given excessive acetate and NAD depletion and play an important role in liver injury. In this regard, novel therapeutic approaches based on epigenetic modulators are increasingly proposed. MicroRNAs, epigenetic modulators acting at the post-transcriptional level, appear to be promising new targets for the treatment of ALD.

Methods

MiR-873-5p levels were measured in 23 liver tissue from Patients with ALD, and GNMT levels during ALD were confirmed using expression databases (transcriptome n = 62, proteome n = 68). High-resolution proteomics and metabolomics in mice following the Gao-binge model were used to investigate miR-873-5p expression in ALD. Hepatocytes exposed to 50 mM alcohol for 12 h were used to study toxicity. The effect of anti-miR-873-5p in the treatment outcomes of ALD was investigated.

Results

The analysis of human and preclinical ALD samples revealed increased expression of miR-873-5p in the liver. Interestingly, there was an inverse correlation with NNMT, suggesting a novel mechanism for NAD depletion and aberrant acetylation during ALD progression. High-resolution proteomics and metabolomics identified miR-873-5p as a key regulator of NAD metabolism and SIRT1 deacetylase activity. Anti-miR-873-5p reduced NNMT activity, fuelled the NAD salvage pathway, restored the acetylome, and modulated the levels of NF-κB and FXR, two known SIRT1 substrates, thereby protecting the liver from apoptotic and inflammatory processes, and improving bile acid homeostasis.

Conclusions

These data indicate that targeting miR-873-5p, a repressor of GNMT previously associated with NAFLD and acetaminophen-induced liver failure. is a novel and attractive approach to treating alcohol-induced hepatoxicity.

Impact and implications

The role of miR-873-5p has not been explicitly examined in the progression of ALD, a pathology with no therapeutic options. In this study, inhibiting miR-873-5p exerted hepatoprotective effects against ALD through rescued SIRT1 activity and consequently restored bile acid homeostasis and attenuated the inflammatory response. Targeting hepatic miR-873-5p may represent a novel therapeutic approach for the treatment of ALD.

Nicotinamide Riboside and Phycocyanin Oligopeptides Affect Stress Susceptibility in Chronic Corticosterone-Exposed Rats

Nicotinamide riboside (NR) is an NAD+ precursor capable of regulating mammalian cellular metabolism. Phycocyanin oligopeptide (PC), a phytonutrient found in blue-green algae, has antioxidant and anti-inflammatory properties. This study explored the effects of NR, PC, and their combination on the telomere length as well as inflammatory and antioxidant status of rats under chronic stress conditions (CS). Forty-nine rats were allocated into seven groups: control, chronic stress (CS), CS with NR (26.44 mg/kg), a low dose of 2.64 mg/kg of PC (PC-LD), or a high dose of 26.44 mg/kg PC (PC-HD), NR + PC-LD, and NR + PC-HF. The rats were given daily corticosterone injections (40 mg/kg) to induce stress conditions, or NR and PC were orally administered for 21 days. NR and PC supplementation, particularly NR plus PC, increased the serum antioxidant enzyme activities, hepatic nicotinamide adenine (NAD+) content, and telomere length (p < 0.001 for all) compared to the CS group. The levels of serum malondialdehyde (MDA), liver interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), IL-1β, and IL-8 were reduced under the CS condition (p < 0.001). In addition, CS decreased the levels of hepatic telomere-related proteins and sirtuins (SIRT1 and 3), whereas administration of NR and PC or their combination to CS-exposed rats increased the levels of telomere-related proteins (e.g., POT1b, TRF1 and TRF2), SIRT3 and NAMPT (p < 0.05). In conclusion, NR and PC, especially their combination, can alleviate metabolic abnormalities by enhancing hepatic cytokines, SIRT3, NAMPT, and NAD+ levels in CS-exposed rats. More research is needed to further elucidate the potential health effects of the combination of NR and PC in humans.

Autophagy, Oxidative Stress, and Alcoholic Liver Disease: A Systematic Review and Potential Clinical Applications

Ethanol consumption triggers oxidative stress by generating reactive oxygen species (ROS) through its metabolites. This process leads to steatosis and liver inflammation, which are critical for the development of alcoholic liver disease (ALD). Autophagy is a regulated dynamic process that sequesters damaged and excess cytoplasmic organelles for lysosomal degradation and may counteract the harmful effects of ROS-induced oxidative stress. These effects include hepatotoxicity, mitochondrial damage, steatosis, endoplasmic reticulum stress, inflammation, and iron overload. In liver diseases, particularly ALD, macroautophagy has been implicated as a protective mechanism in hepatocytes, although it does not appear to play the same role in stellate cells. Beyond the liver, autophagy may also mitigate the harmful effects of alcohol on other organs, thereby providing an additional layer of protection against ALD. This protective potential is further supported by studies showing that drugs that interact with autophagy, such as rapamycin, can prevent ALD development in animal models. This systematic review presents a comprehensive analysis of the literature, focusing on the role of autophagy in oxidative stress regulation, its involvement in organ-organ crosstalk relevant to ALD, and the potential of autophagy-targeting therapeutic strategies.

Prognostic value of sirtuin family members and experimental verification identify SIRT5 as diagnostic biomarkers in clear cell renal cell carcinoma

Background

The sirtuins (SIRTs) family is a nicotinamide adenine dinucleotide (NAD+) family of dependent deacetylases, which includes SIRT1-7. This family is related to the development and progression of various tumors. However, a comprehensive analysis of the role of SIRTs in clear cell renal cell carcinoma (ccRCC) is still lacking, and there are few reports on the inhibitory role of SIRT5 in ccRCC.

Methods

We used immunohistochemical analysis, and several bioinformatic databases to perform an integrated analysis of the expression and prognostic value of SIRT5 and other SIRT family members in ccRCC along with the associated immune cell infiltration. These databases include TIMER, THPA, cell culture, UALCAN, cBioPortal, WebGestalt, Metascape, DiseaseMeth, STRING database, and Cytoscape.

Results

The protein expression of SIRT1, 2, 3, 6, and 7 were upregulated in ccRCC for the Human Protein Atlas database, whereas the expression of SIRT4 and SIRT5 was decreased. The expression based on tumor stage, and grade followed a similar trend. Kaplan-Meier analysis showed that high SIRT4 and SIRT5 expression was positively related to better overall survival (OS), whereas SIRT6 and SIRT7 expression was positively related to worse OS. Further, high SIRT3 expression was related to worse relapse-free survival (RFS), whereas high SIRT5 expression was related to better RFS. To explore the mechanism underlying the function of SIRTs in ccRCC, we also used several databases to perform the functional enrichment analysis and explore the relationship between infiltrating immune cells and seven SIRT family members in ccRCC. The results showed that several SIRT family members, and particularly SIRT5, are correlated with the infiltration of some important immune cells. The protein expression of SIRT5 was significantly lower in tumor tissue compared to normal tissue and was negatively related to the age of the patient ccRCC individual tumor stages, and grades. In human ccRCC samples, strong IHC staining expression of SIRT5 was displayed in adjacent normal tissue than in tumor tissues.

Conclusion

SIRT5 may be a prognostic marker and a novel strategy for the treatment of ccRCC.

Aqueous extract of Artemisia capillaris improves non-alcoholic fatty liver and obesity in mice induced by high-fat diet

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases and is a nutritional metabolic disease. Artemisia capillaris (AC) is the above-ground dried part of Artemisia capillaris Thunb. or Artemisia scoparia Waldst. et Kit., a natural medicinal plant with pharmacological effects of heat-clearing and biliary-promoting. In order to evaluate the therapeutic effect of Artemisia capillaris on NAFLD and obesity, experiments were conducted using aqueous extracts of Artemisia capillaris (WAC) to intervene in NAFLD models in vivo and in vitro. In vivo experiments were performed using HFD-fed (high fat diet) C57BL/6 mice to induce NAFLD model, and in vitro experiments were performed using oleic acid to induce HepG2 cells to construct NAFLD cell model. H.E. staining and oil red O staining of liver tissue were used to observe hepatocytes. Blood biochemistry analyzer was used to detect serum lipid levels in mice. The drug targets and mechanism of action of AC to improve NAFLD were investigated by western blotting, qRT-PCR and immunofluorescence. The results showed that C57BL/6 mice fed HFD continuously for 16 weeks met the criteria for NAFLD in terms of lipid index and hepatocyte fat accumulation. WAC was able to reverse the elevation of serum lipid levels induced by high-fat diet in mice. WAC promoted the phosphorylation levels of PI3K/AKT and AMPK in liver and HepG2 cells of NAFLD mice, inhibited SREBP-1c expression, reduced TG and lipogenesis, and decreased lipid accumulation. In summary, WAC extract activates PI3K/AKT pathway, reduces SREBP-1c protein expression by promoting AMPK phosphorylation, and decreases fatty acid synthesis and TG content in hepatocytes. AC can be used as a potential health herb to improve NAFLD and obesity.

Roles of sirtuins in asthma

Sirtuins are nicotinamide adenine dinucleotide (NAD⁺)-dependent lysine deacylases and deacetylases that participate in a variety of cellular processes, including transcriptional activity, energy metabolism, DNA damage response, inflammation, apoptosis, autophagy, and oxidative stress. As a result, sirtuins are linked to multiple pathophysiological processes, such as cardiovascular diseases, metabolic diseases, autoimmune diseases, infectious diseases, and respiratory diseases. Asthma is the most common respiratory disease, which is characterized by airway inflammation and airway remodeling. Accumulating evidence has indicated that sirtuins are involved in the pathogenesis of asthma. Furthermore, some studies have suggested that sirtuin modulators are potential agents for the treatment of asthma via alteration of the expression or activity of sirtuins. In this review, we illustrate the role of sirtuins in asthma, discuss related molecular mechanisms, and evaluate the sirtuins-targeted therapy for asthma.

Fu brick tea alleviates alcoholic liver injury by modulating the gut microbiota-liver axis and inhibiting the hepatic TLR4/NF-κB signaling pathway

This study first evaluated the protective effects of Fu brick tea water extracts (FTE) on alcoholic liver injury and its underlying mechanism in C57BL/6J mice. Oral administration of FTE by oral gavage (400 mg per kg bw) for 12 weeks significantly alleviated lipid metabolism disorder, reduced the activities of serum ALT and AST, decreased the expression of the liver CYP2E1 gene, and enhanced the antioxidant capacities of the livers in alcohol-fed mice (p < 0.05). FTE also relieved alcohol-induced gut microbiota dysbiosis by promoting the proliferation of probiotics such as Muribaculaceae and Lactobacillus, and subsequently increased the cecal levels of short-chain fatty acids (SCFAs) and decreased the tryptophan content of alcohol-fed mice (p < 0.05). Importantly, FTE was found to improve the alcohol-impaired gut barrier function by up-regulating the expression of the epithelial tight junction protein. Accordingly, FTE decreased the circulating lipopolysaccharide (LPS) and thus inhibited the hepatic TLR4/NF-κB signaling pathway to ameliorate alcoholic liver injury. Cumulatively, these findings shed light on the important role of the gut microbiota-liver axis behind the protective efficacy of FTE on alcoholic liver injury.