Diallyl disulfide ameliorates ethanol-induced liver steatosis and inflammation by maintaining the fatty acid catabolism and regulating the gut-liver axis

Biphasic effects of ethanol consumption on N,N-dimethylformamide-induced liver injury in mice

N,N-Dimethylformamide (DMF) is a well-documented occupational hazardous material, which can induce occupational liver injury. The current study was designed to investigate whether ethanol consumption can affect DMF-induced hepatotoxicity and the potential underlying mechanisms involved. We found that a single dose of ethanol (1.25, 2.5, or 5 g/kg bw by gavage) significantly repressed the increase in serum alanine transaminase (ALT) and aspartate transaminase (AST) activities and alleviated the liver histopathological changes in mice challenged with 3 g/kg DMF. In contrast, long-term moderate drinking (2.5 g/kg bw) significantly aggravated the repeated DMF (0.7 g/kg bw) exposure-induced increase in the serum ALT and AST activities. Mechanistically, acute ethanol consumption suppressed DMF-induced activation of the NLR family pyrin domain-containing protein 3 (NLRP3) inflammasome, while long-term moderate ethanol consumption promoted hepatocyte apoptosis in the mouse liver. Notably, cytochrome P4502E1 (CYP2E1) protein level and activity in mouse livers were not significantly affected by ethanol per se in the two models. These results confirm that regular drinking can increase the risk of DMF-induced hepatotoxicity, and suggest that DMF-handling workers should avoid consuming ethanol to reduce the risk of DMF-indued liver injury.

NLRP3 inflammasome activation triggers severe inflammatory liver injury in N, N-dimethylformamide-exposed mice

N,N-dimethylformamide (DMF) is a widely utilized chemical solvent with various industrial applications. Previous studies have indicated that the liver is the most susceptible target to DMF exposure, whereas the underlying mechanisms remain to be elucidated. This study aimed to investigate the role of NLRP3 inflammasome in DMF-induced liver injury in mice by using two NLRP3 inflammasome inhibitors, Nlrp3-/- mice, Nfe2l2-/- mice, and a macrophage-depleting agent. RNA sequencing revealed that endoplasmic reticulum (ER) stress and NLRP3 inflammasome-associated pathways were activated in the mouse liver after acute DMF exposure, which was validated by Western blotting. Interestingly, DMF-induced liver injury was effectively suppressed by two inflammasome inhibitors, MCC950 and Dapansutrile. In addition, knockout of Nlrp3 markedly attenuated DMF-induced liver injury without affecting the metabolism of DMF. Furthermore, silencing Nfe2l2 aggravated the liver injury and the NLRP3 inflammasome activation in mouse liver. Finally, the depletion of hepatic macrophages by clodronate liposomes significantly reduced the liver damage caused by DMF. These results suggest that NLRP3 inflammasome activation is the upstream molecular event in the development of acute liver injury induced by DMF.

PPARβ/δ as a promising molecular drug target for liver diseases: A focused review

Various liver diseases pose great threats to humans. Although the etiologies of these liver diseases are quite diverse, they share similar pathologic phenotypes and molecular mechanisms such as oxidative stress, lipid and glucose metabolism disturbance, hepatic Kupffer cell (KC) proinflammatory polarization and inflammation, insulin resistance, and hepatic stellate cell (HSC) activation and proliferation. Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) is expressed in various types of liver cells with relatively higher expression in KCs and HSCs. Accumulating evidence has revealed the versatile functions of PPARβ/δ such as controlling lipid homeostasis, inhibiting inflammation, regulating glucose metabolism, and restoring insulin sensitivity, suggesting that PPARβ/δ may serve as a potential molecular drug target for various liver diseases. This article aims to provide a concise review of the structure, expression pattern and biological functions of PPARβ/δ in the liver and its roles in various liver diseases, and to discuss potential future research perspectives.

Melosira nummuloides Ethanol Extract Ameliorates Alcohol-Induced Liver Injury by Affecting Metabolic Pathways

Melosira nummuloides is a microalga with a nutritionally favorable polyunsaturated fatty acid profile. In the present study, M. nummuloides ethanol extract (MNE) was administered to chronic-binge alcohol-fed mice and alcohol-treated HepG2 cells, and its hepatoprotective effects and underlying mechanisms were investigated. MNE administration reduced triglyceride (TG), total cholesterol (T-CHO), and liver injury markers, including aspartate transaminase (AST) and alanine transaminase (ALT), in the serum of chronic-binge alcohol-fed mice. However, MNE administration increased the levels of phosphorylated adenosine monophosphate-activated protein kinase (P-AMPK/AMPK) and PPARα, which was accompanied by a decrease in SREBP-1; this indicates that MNE can inhibit adipogenesis and improve fatty acid oxidation. Moreover, MNE administration upregulated the expression of antioxidant enzymes, including SOD, NAD(P)H quinone dehydrogenase 1, and GPX, and ameliorated alcohol-induced inflammation by repressing the Akt/NFκB/COX-2 pathway. Metabolomic analysis revealed that MNE treatment modulated many lipid metabolites in alcohol-treated HepG2 cells. Our study findings provide evidence for the efficacy and mechanisms of MNE in ameliorating alcohol-induced liver injury.

The Role of Oxidative Stress in Alcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis of Preclinical Studies

Alcoholic Fatty Liver Disease (AFLD) is characterized by the accumulation of lipids in liver cells owing to the metabolism of ethanol. This process leads to a decrease in the NAD+/NADH ratio and the generation of reactive oxygen species. A systematic review and meta-analysis were conducted to investigate the role of oxidative stress in AFLD. A total of 201 eligible manuscripts were included, which revealed that animals with AFLD exhibited elevated expression of CYP2E1, decreased enzymatic activity of antioxidant enzymes, and reduced levels of the transcription factor Nrf2, which plays a pivotal role in the synthesis of antioxidant enzymes. Furthermore, animals with AFLD exhibited increased levels of lipid peroxidation markers and carbonylated proteins, collectively contributing to a weakened antioxidant defense and increased oxidative damage. The liver damage in AFLD was supported by significantly higher activity of alanine and aspartate aminotransferase enzymes. Moreover, animals with AFLD had increased levels of triacylglycerol in the serum and liver, likely due to reduced fatty acid metabolism caused by decreased PPAR-α expression, which is responsible for fatty acid oxidation, and increased expression of SREBP-1c, which is involved in fatty acid synthesis. With regard to inflammation, animals with AFLD exhibited elevated levels of pro-inflammatory cytokines, including TNF-a, IL-1β, and IL-6. The heightened oxidative stress, along with inflammation, led to an upregulation of cell death markers, such as caspase-3, and an increased Bax/Bcl-2 ratio. Overall, the findings of the review and meta-analysis indicate that ethanol metabolism reduces important markers of antioxidant defense while increasing inflammatory and apoptotic markers, thereby contributing to the development of AFLD.

Galangin Prevents Against Ethanol-Induced Intestinal Barrier Dysfunction and NLRP3 Inflammasome Activation via NF-κB/MAPK Signaling Pathways in Mice and Caco-2 Cells

The potential of natural phytochemicals in addressing ethanol-related public safety concerns has been garnering attention. Galangin, a potent flavonoid renowned for its antioxidative and anti-inflammatory characteristics, is derived from the galanga plant, and propolis is derived from bees. Here, we documented the effects of galangin on ethanol-stimulated intestinal tight junction damage and investigated its potential protective mechanism in both in vivo and in vitro models, which has not been extensively investigated. Our results revealed that galangin efficaciously mitigated ethanol-induced intestine injury and dysfunction of the intestinal barrier. Concurrently, galangin significantly counteracted the ethanol-induced upregulation of NLRP3 inflammasome-associated proteins and activated the mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) signaling pathways in both the mouse colon and Caco-2 cells. Interestingly, similar to galangin, inhibitors of MAPKs and the NF-κB p65 reduced ethanol-induced NLRP3 inflammasome activation and intestinal tight junction damage. To sum up, our results showed that galangin blocks the ethanol-induced perturbation of the intestinal barrier and activation of the NLRP3 inflammasome via the NF-κB/MAPK signaling pathways.

The role of hydrogen sulfide regulation of pyroptosis in different pathological processes

Pyroptosis is one kind of programmed cell death in which the cell membrane ruptures and subsequently releases cell contents and pro-inflammatory cytokines including IL-1β and IL-18. Pyroptosis is caused by many types of pathological stimuli, such as hyperglycemia (HG), oxidative stress, and inflammation, and is mediated by gasdermin (GSDM) protein family. Increasing evidence indicates that pyroptosis plays an important role in multiple diseases, such as cancer, kidney diseases, inflammatory diseases, and cardiovascular diseases. Therefore, the regulation of pyroptosis is crucial for the occurrence, development, and treatment of many diseases. Hydrogen sulfide (H2S) is a biologically active gasotransmitter following carbon monoxide (CO) and nitrogen oxide (NO) in mammalian tissues. So far, three enzymes, including 3-mercaptopyruvate sulphurtransferase (3-MST), cystathionine γ- Lyase (CSE), and Cystine β-synthesis enzyme (CBS), have been found to catalyze the production of endogenous H2S in mammals. H2S has been reported to have multiple biological functions including anti-inflammation, anti-oxidative stress, anti-apoptosis and so on. Hence, H2S is involved in various physiological and pathological processes. In recent years, many studies have demonstrated that H2S plays a critical role by regulating pyroptosis in various pathological processes, such as ischemia-reperfusion injury, alcoholic liver disease, and diabetes cardiomyopathy. However, the relevant mechanism has not been completely understood. Therefore, elucidating the mechanism by which H2S regulates pyroptosis in diseases will help understand the pathogenesis of multiple diseases and provide important new avenues for the treatment of many diseases. Here, we reviewed the progress of H2S regulation of pyroptosis in different pathological processes, and analyzed the molecular mechanism in detail to provide a theoretical reference for future related research.

Calenduloside E ameliorates non-alcoholic fatty liver disease via modulating a pyroptosis-dependent pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver condition that can have multiple underlying causes. There are no satisfactory chemical or biological drugs for the treatment of NAFLD. Longyasongmu, the bark and root of Aralia elata (Miq.) Seem, is used extensively in traditional Chinese medicine (TCM) and has been used in treating diverse liver diseases including NAFLD. Based on Aralia elata (Miq.) Seem as the main ingredient, Longya Gantai Capsules have been approved for use in China for the treatment of acute hepatitis and chronic hepatitis. Calenduloside E (CE), a natural pentacyclic triterpenoid saponin, is a significant component of saponin isolated from the bark and root of Aralia elata (Miq.) Seem. However, the role and mechanism of anti-NAFLD effects of CE is still unclear.

AIM OF THE STUDY

The objective of this study was to examine the potential mechanisms underlying the protective effect of CE on NAFLD.

MATERIALS AND METHODS

In this study, an NAFLD model was established by Western diet in apoE-/- mice, followed by treatment with various doses of CE (5 mg/kg, 10 mg/kg). The anti-NAFLD effect of CE was assessed by the liver injury, lipid accumulation, inflammation, and pro-fibrotic phenotype. The mechanism of CE in ameliorating NAFLD was studied through transcriptome sequencing (RNA-seq). In vitro, the mouse hepatocytes (AML-12) were stimulated in lipid mixtures with CE and performed the exploration and validation of the relevant pathways using Western blot, immunofluorescence, etc. RESULTS: The findings revealed a significant improvement in liver injury, lipid accumulation, inflammation, and pro-fibrotic phenotype upon CE administration. Furthermore, RNAseq analysis indicated that the primary pathway through which CE alleviates NAFLD involves pyroptosis-related inflammatory cascade pathways. Furthermore, it was observed that CE effectively suppressed inflammasome-mediated pyroptosis both in vivo and in vitro. Remarkably, the functional enrichment analysis of RNA-seq data revealed that the PI3K-Akt signaling pathway is the primarily Signaling transduction pathway modulated by CE treatment. Subsequent experimental outcomes provided further validation of CE's ability to hinder inflammasome-mediated pyroptosis through the inhibition of PI3K/AKT/NF-κB signaling pathway.

CONCLUSIONS

These findings present a novel pharmacological role of CE in exerting anti-NAFLD effects by inhibiting pyroptosis signaling pathways.

Astragaloside IV ameliorate acute alcohol-induced liver injury in mice via modulating gut microbiota and regulating NLRP3/caspase-1 signaling pathway

PURPOSE

Astragaloside IV (AS-IV) is a natural saponin substance extracted from the plant Radix Astragali with anti-inflammatory, antioxidant, anti-apoptotic, and liver-protecting effects. This study was to evaluate the liver protection effect of AS-IV on mice after acute alcohol stimulation.

MATERIALS AND METHODS

Mice were orally administrated with AS-IV (50, 150, and 500 mg/kg, respectively), and sodium carboxymethyl cellulose (CMC, 50 mg/kg) daily for 7 days, before giving five alcohol-intragastric injections.

RESULTS

Results suggested that the levels of serum ALT and AST, liver SOD, GSH-PX, 4-HNE, and MDA, serum and liver TNF-α, IL-1β, and IL-6, serum lipopolysaccharide (LPS), lipopolysaccharide binding protein (LBP), diamine oxidase (DAO) and Myeloperoxidase (MPO), the mRNA and protein expression of hepatic NLRP3, Caspase-1, IL-1β, and IL-18 were significantly decreased in AS-IV-treated mice compared with the model group. Moreover, the effect of AS-IV on histopathology of liver tissue confirmed its protective function. Furthermore, AS-IV ameliorated the gut microbiota imbalance and adjusted the abundance of the following dysfunctional bacteria closer to the control group: Butyricicoccus, Turicibacter, Akkermansia, Anaerotruncus, and Mucispirillum. A strong correlation between intestinal bacteria and potential biomarkers was found.

CONCLUSION

Together, our findings indicated that AS-IV exert the hepatoprotective effect by modulating the gut microbiota imbalance and regulating NLRP3/Caspase-1 signaling pathway.

Allyl methyl disulfide (AMDS) prevents N,N-dimethyl formamide-induced liver damage by suppressing oxidative stress and NLRP3 inflammasome activation

N,N-dimethylformamide (DMF), a widely consumed industrial solvent with persistent characteristics, can induce occupational liver damage and pose threats to the general population due to the enormous DMF-containing industrial efflux and emission from indoor facilities. This study was performed to explore the roles of allyl methyl disulfide (AMDS) in liver damage induced by DMF and the underlying mechanisms. AMDS was found to effectively suppress the elevation in the liver weight/body weight ratio and serum aminotransferase activities, and reduce the mortality of mice induced by DMF. In addition, AMDS abrogated DMF-elicited increases in malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) levels and decreases in glutathione (GSH) levels in mouse livers. The increase in macrophage number, mRNA expression of M1 macrophage biomarkers, and protein expression of key components in the NF-κB pathway and NLRP3 inflammasome induced by DMF exposure were all suppressed by AMDS in mouse livers. Furthermore, AMDS inhibited DMF-induced cell damage and NF-κB activation in cocultured AML12 hepatocytes and J774A.1 macrophages. However, AMDS per se did not significantly affect the protein level and activity of CYP2E1. Collectively, these results demonstrate that AMDS effectively ameliorates DMF-induced acute liver damage possibly by suppressing oxidative stress and inactivating the NF-κB pathway and NLRP3 inflammasome.

Anti-Leishmania amazonensis Activity, Cytotoxic Features, and Chemical Profile of Allium sativum (Garlic) Essential Oil

Human tegumentary leishmaniasis (HTL) is a serious tropical disease caused by Leishmania amazonensis. Developing new leishmanicidal agents can help overcome current treatment challenges, such as drug resistance and toxicity. Essential oils are a source of lipophilic substances with diverse therapeutic properties. This study aimed to determine the anti-L. amazonensis activity, cytotoxicity, and chemical profile of Allium sativum essential oil (ASEO). The effect of ASEO on parasite and mammalian cells viability was evaluated using resazurin and MTT assays, respectively. The oil's effect against intracellular amastigotes was also determined. Transmission electron microscopy was used to assess the ultrastructural changes induced by ASEO. In addition, the chemical constituents of ASEO were identified by gas chromatography-mass spectrometry (GC-MS). The cytotoxic potential was evaluated in vitro and in silico. The oil displayed IC₅₀ of 1.76, 3.46, and 3.77 µg/mL against promastigotes, axenic, and intracellular amastigotes, respectively. Photomicrographs of treated parasites showed plasma membrane disruption, increased lipid bodies, and autophagic-like structures. ASEO chemical profiling revealed 1,2,4,6-tetrathiepane (24.84%) and diallyl disulfide (16.75%) as major components. Computational pharmacokinetics and toxicological analysis of ASEO's major components demonstrated good oral bioavailability and better toxicological endpoints than the reference drugs. Altogether, the results suggest that ASEO could be an alternative drug candidate against HTL.

High-fat diet promotes multiple binges-induced liver injury via promoting hepatic macrophage proinflammatory polarization

High-fat diet (HFD) and ethanol could synergistically induce liver damage, but the underlying mechanisms remain to be elucidated. M1-polarized macrophages have been demonstrated to be key players in ethanol-induced liver damage. The current study was designed to investigate whether hepatic steatosis could promote ethanol-induced liver injury by promoting liver macrophage M1 polarization. In the in vivo study, 12 weeks of HFD feeding induced a moderate increase in the F4/80 expression and protein levels of p-IKKα/β, p-IκBα, and p-p65, which was suppressed by single binge. In contrast, 8 weeks of HFD and multiple binges (two binges per week during the last 4 weeks) synergistically increased the F4/80 expression, mRNA levels of M1 polarization biomarkers including Ccl2, Tnfa, and Il1b, and protein levels of p65, p-p65, COX2, and Caspase 1. In the in vitro study, a nontoxic free fatty acids (FFAs) mixture (oleic acid/palmitic acid = 2: 1) induced a moderate increase of protein levels of p-p65 and NLRP3 in murine AML12 hepatocytes, which was inhibited by ethanol co-exposure. Ethanol alone induced proinflammatory polarization of murine J774A.1 macrophages evidenced by the enhanced secretion of TNF-α, increased mRNA levels of Ccl2, Tnfa, and Il1b, and upregulated protein levels of p65, p-p65, NLRP3, and Caspase 1, which was augmented by FFAs exposure. Collectively, these results suggest that HFD and multiple binges could synergistically induce liver damage by promoting the proinflammatory activation of macrophages in mice livers.

The potential health risks of short-chain chlorinated paraffin: A mini-review from a toxicological perspective

Short-chain chlorinated paraffins (SCCPs) are ubiquitously distributed in various environmental matrics due to their wide production and consumption globally in the past and ongoing production and use in some developing countries. SCCPs have been detected in various human samples including serum, milk, placenta, nail, and hair, and internal SCCP levels were found to be positively correlated with biomarkers of some diseases. While the environmental occurrence has been reported in a lot of studies, the toxicity and underlying molecular mechanisms of SCCPs remain largely unknown. The current tolerable daily intakes (TDIs) recommended by the world health organization/international programme on chemical safety (WHO/IPCS, 100 μg/kg bw/d) and the UK Committee on Toxicity (COT, 30 μg/kg bw/d) were obtained based on a no observed adverse effect level (NOAEL) of SCCP from the repeated-dose study (90 d exposure) in rodents performed nearly 40 years ago. Importantly, the health risks assessment of SCCPs in a variety of studies has shown that the estimated daily intakes (EDIs) may approach and even over the established TDI by UK COT. Furthermore, recent studies revealed that lower doses of SCCPs could also result in damage to multiple organs including the liver, kidney, and thyroid. Long-term effects of SCCPs at environmental-related doses are warranted.

Bacillus subtilis pretreatment alleviates ethanol-induced acute liver injury by regulating the Gut-liver axis in mice

This study was designed to investigate the hepatoprotective effects of Bacillus subtilis, a commensal bacterial species in the human gut, on ethanol-induced acute liver damage and the underlying mechanisms in mice. Male ICR mice challenged with three doses of ethanol (5.5 g/kg BW) exhibited a significant increase in serum aminotransferase activities and TNF-α level, liver fat accumulation, and activation of NF-κB signaling and NLRP3 inflammasome, which was suppressed by pretreatment with Bacillus subtilis. Besides, Bacillus subtilis inhibited acute ethanol-induced intestinal villi shortening and epithelial loss, the decline of protein levels of intestinal tight junction protein ZO-1 and occludin, and elevation of serum LPS level. Furthermore, the upregulation of mucin-2 (MUC2) and the downregulation of anti-microbial Reg3B and Reg3G levels induced by ethanol were repressed by Bacillus subtilis. Lastly, Bacillus subtilis pretreatment significantly increased the abundance of the intestinal Bacillus, but had no effects on the binge drinking-induced increase of Prevotellaceae abundance. These results demonstrate that Bacillus subtilis supplementation could ameliorate binge drinking-induced liver injury, and thus may serve as a functional dietary supplement for binge drinkers.

Long-term exposure to low-dose Di(2-ethylhexyl) phthalate aggravated high fat diet-induced obesity in female mice

The potential obesogenic roles of di(2-ethylhexyl) phthalate (DEHP) have attracted great attention. The current study aimed to evaluate the combined effects of chronic low-dose DEHP (0.05 mg/kg BW) and a high-fat diet (HFD) on obesity in female mice and explore the underlying mechanisms. We found that low-dose DEHP challenge for 29 weeks increased fat accumulation both in CD- and HFD-fed mice and significantly accelerated the weight gain without affecting food intake in HFD-fed mice. DEHP exposure reduced the energy metabolism, down-regulated the uncoupling protein 1 (UCP1) and total oxidative phosphorylation (OXPHOS) proteins expression in the brown adipose tissue, and up-regulated the PPARγ expression and its phosphorylation at Ser273 in white adipose tissue (WAT). Besides, the combination of DEHP and HFD drove the remodeling of gut microbiota of mice, characterized by the reduced richness and diversity and the elevated Firmicutes to Bacteroidetes (F/B) ratio. Short-chain fatty acids (SCFAs) analysis revealed that DEHP and HFD cotreatment led to a decrease in levels of acetic acid, butyric acid, and pentanoic acid. Interestingly, sodium butyrate (NaB) significantly inhibited the adipogenesis and lipid accumulation of NIH/3T3 mouse embryonic fibroblasts (PPARγ2 overexpression) and the PPARγ phosphorylation at Ser273 induced by DEHP or MEHP. These findings demonstrate that chronic low-dose DEHP challenge could prompt fat accumulation by increasing PPARγ phosphorylation at Ser273 and decreasing thermogenesis in BAT, which might be associated with the SCFAs reduction.

Lipid metabolism disorders contribute to hepatotoxicity of ICR mice induced by nitrosamines exposure

Health risks caused by crucial environmental carcinogens N-nitrosamines triggered ubiquitous attention. As the liver exerted vital function through metabolic process, lipid metabolism disorders have been confirmed as potential drivers for toxicological effects, and the mechanisms of lipid regulation related to hepatotoxicity induced by N-nitrosamines remained largely unclear. In this study, we comprehensively explored the disturbance of hepatic lipid homeostasis in mice induced by nitrosamines. The results implied that nitrosamines exposure induced hepatotoxicity accompanied by liver injury, inflammatory infiltration, and hepatic edema. Lipidomics profiling analysis indicated the decreased levels of phosphatidic acids (PA), phosphatidylcholines (PC), phosphatidylethanolamines (PE), lyso-phosphatidylcholines (LPC), lyso-phosphatidylethanolamines (LPE), diacylglycerols (DAG) and triacylglycerols (TAG), the elevation of ceramides (Cer) and decomposition of free fatty acids (FFA) in high-dose nitrosamines exposure group. Importantly, nitrosamines exposure promoted fatty acid oxidation (FAO) by facilitating fatty acid uptake and decomposition, together with the upregulation of genes associated with FAO accompanied by the activation of inflammatory cytokines TNF-α, IL-1β and NLRP3. Furthermore, fatty acid translocase CD36-mediated fatty acid oxidation was correlated with the enhancement of oxidative stress in the liver caused by nitrosamines exposure. Overall, our results contributed to the new strategies to interpret the early toxic effects of nitrosamines exposure.