Mitochondria and the NLRP3 Inflammasome in Alcoholic and Nonalcoholic Steatohepatitis

Diosgenin attenuates metabolic-associated fatty liver disease through the hepatic NLRP3 inflammasome-dependent signaling pathway

Metabolic-associated fatty liver disease (MAFLD) is one of the most common liver diseases worldwide; however, its pathogenesis and treatment methods have not been perfected. NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) is a promising therapeutic target for MAFLD. Diosgenin (DG) is a natural compound that was identified in a traditional Chinese herbal medicine, which has pharmacological effects, such as anti-inflammatory, antioxidant, hepatoprotective, and hypolipidemic activities. In this study, we examined the effects and molecular mechanisms of DG on MAFLD in vitro and in vivo. We established a rat model by administering a high-fat diet (HFD). We also generated an in vitro MAFLD model by treating HepG2 cells with free fatty acids (FFAs). The results indicated that DG attenuated lipid accumulation and liver injury in both in vitro and in vivo models. DG downregulated the expression of NLRP3, apoptosis-associated speckle-like protein (ASC), cysteinyl aspartate specific proteinase-1 (caspase-1), gasdermin D (GSDMD), GSDMD-n, and interleukin-1β (IL-1β). In addition, we silenced and overexpressed NLRP3 in vitro to determine the effects of DG on antiMAFLD. Silencing NLRP3 enhanced the effect of DG on the treatment of MAFLD, whereas NLRP3 overexpression reversed its beneficial effects. Taken together, the results show that DG has a favorable effect on attenuating MAFLD through the hepatic NLRP3 inflammasome-dependent signaling pathway. DG represents a natural NLRP3 inhibitor for the MAFLD treatment.

Phosphoglycerate mutase 5 exacerbates alcoholic cardiomyopathy in male mice by inducing prohibitin-2 dephosphorylation and impairing mitochondrial quality control

BACKGROUND

The induction of mitochondrial quality control (MQC) mechanisms is essential for the re-establishment of mitochondrial homeostasis and cellular bioenergetics during periods of stress. Although MQC activation has cardioprotective effects in various cardiovascular diseases, its precise role and regulatory mechanisms in alcoholic cardiomyopathy (ACM) remain incompletely understood.

METHODS

We explored whether two mitochondria-related proteins, phosphoglycerate mutase 5 (Pgam5) and prohibitin 2 (Phb2), influence MQC in male mice during ACM.

RESULTS

Myocardial Pgam5 expression was upregulated in a male mouse model of ACM. Notably, following ACM induction, heart dysfunction was markedly reversed in male cardiomyocyte-specific Pgam5 knockout (Pgam5cKO) mice. Meanwhile, in alcohol-treated male mouse-derived neonatal cardiomyocytes, Pgam5 depletion preserved cell survival and restored mitochondrial dynamics, mitophagy, mitochondrial biogenesis and the mitochondrial unfolded protein response (mtUPR). We further found that in alcohol-treated cardiomyocyte, Pgam5 binds Phb2 and induces its dephosphorylation at Ser91. Alternative transduction of phospho-mimetic (Phb2S91D) and phospho-defective (Phb2S9A) Phb2 mutants attenuated and enhanced, respectively, alcohol-related mitochondrial dysfunction in cardiomyocytes. Moreover, transgenic male mice expressing Phb2S91D were resistant to alcohol-induced heart dysfunction.

CONCLUSIONS

We conclude that ACM-induced Pgam5 upregulation results in Pgam5-dependent Phb2S91 dephosphorylation, leading to MQC destabilisation and mitochondrial dysfunction in heart. Therefore, modulating the Pgam5/Phb2 interaction could potentially offer a novel therapeutic strategy for ACM in male mice.

HIGHLIGHTS

Pgam5 knockout attenuates alcohol-induced cardiac histopathology and heart dysfunction in male mice. Pgam5 KO reduces alcohol-induced myocardial inflammation, lipid peroxidation and metabolic dysfunction in male mice. Pgam5 depletion protects mitochondrial function in alcohol-exposed male mouse cardiomyocytes. Pgam5 depletion normalises MQC in ACM. EtOH impairs MQC through inducing Phb2 dephosphorylation at Ser91. Pgam5 interacts with Phb2 and induces Phb2 dephosphorylation. Transgenic mice expressing a Ser91 phospho-mimetic Phb2 mutant are resistant to ACM.

The Coptidis Rhizoma and Bovis Calculus herb pair attenuates NASH and inhibits the NLRP3 inflammasome activation

The Coptidis Rhizoma and Bovis Calculus herb pair possesses clearing heat and detoxifying effects. The aim of this study was to reveal the effects and mechanisms of the herb pair in the treatment of NASH by network pharmacology and experimental verification. A network pharmacology-based approach was employed to predict the putative mechanism of the herb pair against NASH. The high-fat diet (HFD) and methionine/choline deficient (MCD) diet induced NASH models were used to evaluate efficacy and mechanism of the herb pair. Network pharmacological analysis showed that the herb pair modulated NOD-like receptor pathway. In the HFD mice, herb pair reduced body weight, blood sugar, serum ALT, AST, TBA, TC, TG and LDL-C contents, also improved the general morphology and pathological manifestations. Hepatic transcriptomics study showed that herb pair attenuated NASH by regulating NOD-like receptor signaling pathway. Western blotting showed that herb pair reduced the protein expression levels of NLRP3, cleaved Caspase-1 and cleaved IL-1β. In the MCD mice, herb pair also reduced serum ALT, ALT and TBA levels, improved liver pathological manifestations, inhibited the protein expression levels of NLRP3, cleaved Caspase-1 and cleaved IL-1β. Our findings proved that the Coptidis Rhizoma and Bovis Calculus herb pair attenuates NASH through suppression of NLRP3 inflammasome activation. This will demonstrate effective pharmacological evidence for the clinical application of herb pair.

Rab11b promotes M1-like macrophage polarization by restraining autophagic degradation of NLRP3 in alcohol-associated liver disease

Macrophage polarization is vital to mounting a host defense or repairing tissue in various liver diseases. Excessive activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome is related to the orchestration of inflammation and alcohol-associated liver disease (ALD) pathology. Rab GTPases play critical roles in regulating vesicular transport. In this study we investigated the role of Rab11b in ALD, aiming to identify effective therapeutic targets. Here, we first demonstrated a decreased expression of Rab11b in macrophages from ALD mice. Knockdown of Rab11b by macrophage-specific adeno-associated virus can alleviate alcohol induced liver inflammation, injury and steatosis. We found that LPS and alcohol stimulation promoted Rab11b transferring from the nucleus to the cytoplasm in bone marrow-derived macrophages (BMDM) cells. Rab11b specifically activated the NLRP3 inflammasome in BMDMs and RAW264.7 cells to induce M1 macrophage polarization. Rab11b overexpression in BMDMs inhibited autophagic flux, leading to the suppression of LC3B-mediated NLRP3 degradation. We conclude that impaired Rab11b could alleviate alcohol-induced liver injury via autophagy-mediated NLRP3 degradation.

Mitochondrial dynamics, quality control, and mtDNA in alcohol-associated liver disease and liver cancer

Mitochondria are intracellular organelles responsible for energy production, glucose and lipid metabolism, cell death, cell proliferation, and innate immune response. Mitochondria are highly dynamic organelles that constantly undergo fission, fusion, and intracellular trafficking, as well as degradation and biogenesis. Mitochondrial dysfunction has been implicated in a variety of chronic liver diseases including alcohol-associated liver disease, metabolic dysfunction-associated steatohepatitis, and HCC. In this review, we provide a detailed overview of mitochondrial dynamics, mitophagy, and mitochondrial DNA-mediated innate immune response, and how dysregulation of these mitochondrial processes affects the pathogenesis of alcohol-associated liver disease and HCC. Mitochondrial dynamics and mitochondrial DNA-mediated innate immune response may thereby represent an attractive therapeutic target for ameliorating alcohol-associated liver disease and alcohol-associated HCC.

NLRP3 Inflammasome in Acute and Chronic Liver Diseases

NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3) is an intracellular complex that upon external stimuli or contact with specific ligands, recruits other components, forming the NLRP3 inflammasome. The NLRP3 inflammasome mainly mediates pyroptosis, a highly inflammatory mode of regulated cell death, as well as IL-18 and IL-1β production. Acute and chronic liver diseases are characterized by a massive influx of pro-inflammatory stimuli enriched in reactive oxygen species (ROS) and damage-associated molecular patterns (DAMPs) that promote the assemblage and activation of the NLRP3 inflammasome. As the major cause of inflammatory cytokine storm, the NLRP3 inflammasome exacerbates liver diseases, even though it might exert protective effects in regards to hepatitis C and B virus infection (HCV and HBV). Here, we summarize the current knowledge concerning NLRP3 inflammasome function in both acute and chronic liver disease and in the post liver transplant setting, focusing on the molecular mechanisms involved in NLRP3 activity.

LanGui tea, an herbal medicine formula, protects against binge alcohol-induced acute liver injury by activating AMPK-NLRP3 signaling

BACKGROUND

LanGui tea, a traditional Chinese medicine formulation comprising of Gynostemma pentaphyllum (Thunb.) Makino, Cinnamomum cassia (L.) J. Presl, and Ampelopsis grossedentata (Hand-Mazz) W.T. Wang, has yet to have its potential contributions to alcoholic liver disease (ALD) fully elucidated. Consequently, the objective of this research is to investigate the protective properties of LanGui tea against binge alcohol-induced ALD and the mechanisms underlying its effects.

METHODS

An experimental model of acute alcohol-induced liver disease was performed to assess the protective effects of extract of LanGui tea (ELG) at both 50 and 100 mg.kg-1 dosages on male C57BL/6 mice. Various parameters, including hepatic histological changes, inflammation, lipids content, as well as liver enzymes and interleukin 1β (IL-1β) in the serum were measured. The pharmacological mechanisms of ELG, specifically its effects on adenosine monophosphate-(AMP)-activated protein kinase (AMPK) and NLR family pyrin domain containing 3 (NLRP3) signaling, were investigated through Western blotting, qRT-PCR, ELISA, immunohistochemistry, immunofluorescence analyses, and by blocking the AMPK activity.

RESULTS

ELG demonstrated a mitigating effect on fatty liver, inflammation, and hepatic dysfunction within the mouse model. This effect was achieved by activating AMPK signaling and inhibitingNLRP3 signaling in the liver, causing a reduction in IL-1β generation. In vitro studies further confirmed that ELG inhibited cell damage and IL-1β production in ethanol-induced hepatocytes by enhancing AMPK-NLRP3 signaling. Conversely, the pharmacological inhibition of AMPK activity nearly abrogated such alteration.

CONCLUSIONS

Thus, LanGui tea emerges as a promising herbal therapy for ALD management involving AMPK-NLRP3 signaling.

Mitochondrial Dysfunction in Metabolic Dysfunction Fatty Liver Disease (MAFLD)

Nonalcoholic fatty liver disease (NAFLD) has become an increasingly common disease in Western countries and has become the major cause of liver cirrhosis or hepatocellular carcinoma (HCC) in addition to viral hepatitis in recent decades. Furthermore, studies have shown that NAFLD is inextricably linked to the development of extrahepatic diseases. However, there is currently no effective treatment to cure NAFLD. In addition, in 2020, NAFLD was renamed metabolic dysfunction fatty liver disease (MAFLD) to show that its pathogenesis is closely related to metabolic disorders. Recent studies have reported that the development of MAFLD is inextricably associated with mitochondrial dysfunction in hepatocytes and hepatic stellate cells (HSCs). Simultaneously, mitochondrial stress caused by structural and functional disorders stimulates the occurrence and accumulation of fat and lipo-toxicity in hepatocytes and HSCs. In addition, the interaction between mitochondrial dysfunction and the liver-gut axis has also become a new point during the development of MAFLD. In this review, we summarize the effects of several potential treatment strategies for MAFLD, including antioxidants, reagents, and intestinal microorganisms and metabolites.

Mechanisms of NLRP3 inflammasome activation and the development of peptide inhibitors

The Nucleotide-binding domain leucine-rich repeat and pyrin domain containing receptor 3 (NLRP3), a member of the nucleotide-binding oligomerization domain (NOD) like receptors (NLRs) family, plays an important role in the innate immune response against pathogen invasions. NLRP3 inflammasome consisting of NLRP3 protein, the adapter protein apoptosis-associated speck-like protein containing a caspase recruitment domain (CARD) (ASC), and the effector protein pro-caspase-1, is central to this process. Upon activation, NLRP3 inflammasome initiates the release of inflammatory cytokines and triggers a form of cell death known as pyroptosis. Dysregulation or inappropriate activation of NLRP3 has been implicated in various human diseases, including type 2 diabetes, colitis, depression, and gout. Consequently, understanding the mechanism underlying NLRP3 inflammasome activation is critical for the development of therapeutic drugs. In the pursuit of potential therapeutic agents, peptides present several advantages over small molecules. They offer higher selectivity, increased potency, reduced toxicity, and fewer off-target effects. The advancements in molecular biology have expanded the opportunities for applying peptides in medicine, unlocking their vast medical potential. This review begins by providing a comprehensive summary of recent research progress regarding the mechanisms governing NLRP3 inflammasome activation. Subsequently, we offer an overview of current peptide inhibitors capable of modulating the NLRP3 inflammasome activation pathway.

Korean Chestnut Honey Suppresses HSV-1 Infection by Regulating the ROS-NLRP3 Inflammasome Pathway

Herpes simplex virus 1 (HSV-1) is double-stranded DNA virus that belongs to the Orthoherpesviridae family. It causes serious neurological diseases of the central nervous system, such as encephalitis. The current U.S. Food and Drug Administration (FDA)-approved drugs for preventing HSV-1 infection include acyclovir (ACV) and valacyclovir; however, their long-term use causes severe side effects and often results in the emergence of drug-resistant strains. Therefore, it is important to discover new antiviral agents that are safe and effective against HSV-1 infection. Korean chestnut honey (KCH) has various pharmacological activities, such as antioxidant, antibacterial, and anti-inflammation effects; however, antiviral effects against HSV-1 have not yet been reported. Therefore, we determined the antiviral activity and mechanism of action of KCH after HSV-1 infection on the cellular level. KCH inhibited the HSV-1 infection of host cells through binding and virucidal steps. KCH decreased the production of reactive oxygen species (ROS) and calcium (Ca2+) following HSV-1 infection and suppressed the production of inflammatory cytokines by inhibiting nuclear factor kappa-light-chain-enhancer of activated B cells (NF-кB) activity. Furthermore, we found that KCH inhibited the expression of the nod-like receptor protein 3 (NLRP3) inflammasome during HSV-1 infection. Taken together, the antiviral effects of KCH occur through multiple targets, including the inhibition of viral replication and the ROS-mediated NLRP3 inflammasome pathway. Our findings suggest that KCH has potential for the treatment of HSV-1 infection and related diseases.

BAM15 as a mitochondrial uncoupler: a promising therapeutic agent for diverse diseases

Subcellular organelles dysfunction is implicated in various diseases, including metabolic diseases, neurodegenerative diseases, cancer, and cardiovascular diseases. BAM15, a selective mitochondrial uncoupler, has emerged as a promising therapeutic agent due to its ability to enhance mitochondrial respiration and metabolic flexibility. By disrupting the coupling between electron transport and ATP synthesis, BAM15 dissipates the proton gradient, leading to increased mitochondrial respiration and energy expenditure. This review provides a comprehensive overview of BAM15, including its mechanism of action and potential therapeutic applications in diverse disease contexts. BAM15 has shown promise in obesity by increasing energy expenditure and reducing fat accumulation. In diabetes, it improves glycemic control and reverses insulin resistance. Additionally, BAM15 has potential in non-alcoholic fatty liver disease, sepsis, and cardiovascular diseases by mitigating oxidative stress, modulating inflammatory responses, and promoting cardioprotection. The safety profile of BAM15 is encouraging, with minimal adverse effects and remarkable tolerability. However, challenges such as its high lipophilicity and the need for alternative delivery methods need to be addressed. Further research is necessary to fully understand the therapeutic potential of BAM15 and optimize its application in clinical settings.

Insights of mitochondrial involvement in alcoholic fatty liver disease

Alcoholic liver disease (ALD) is a global concern affecting most of the population and leading to the development of end-stage liver disease. Metabolic alterations due to increased alcohol consumption surge the hepatic accumulation of lipids and develop into a severe form of alcoholic steatohepatitis (ASH), depending on age and the consumption rate. The mitochondria in the hepatocyte actively regulate metabolic homeostasis and are disrupted in ALD pathogenesis. The increased NADH upon ethanol metabolism inhibits the mitochondrial oxidation of fatty acids, alters oxidative phosphorylation, and favors de novo lipogenesis. The higher mitochondrial respiration in early ALD increases free radical generation, whereas mitochondrial respiration is uncoupled in chronic ALD, affecting the cellular energy status. The defective glutathione importer due to excessive cholesterol loading and low adenosine triphosphate accounts for additional oxidative stress leading to hepatocyte apoptosis. The defective mitochondrial transcription machinery and sirtuins function in ALD affect mitochondrial function and biogenesis. The metabolites of ethanol metabolism epigenetically alter the gene expression profile of hepatic cell populations by modulating the promoters and sirtuins, aiding hepatic fibrosis and inflammation. The defect in mitophagy increases the accumulation of megamitochondria in hepatocytes and attracts immune cells by releasing mitochondrial damage-associated molecular patterns to initiate hepatic inflammation and ASH progression. Thus, maintaining mitochondrial lipid homeostasis and antioxidant capacity pharmacologically could provide a better outcome for ALD management.

Anti-Angiogenic Effects of Natural Compounds in Diet-Associated Hepatic Inflammation

Alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD) are the most common causes of chronic liver disease and are increasingly emerging as a global health problem. Such disorders can lead to liver damage, resulting in the release of pro-inflammatory cytokines and the activation of infiltrating immune cells. These are some of the common features of ALD progression in ASH (alcoholic steatohepatitis) and NAFLD to NASH (non-alcoholic steatohepatitis). Hepatic steatosis, followed by fibrosis, lead to a continuous progression accompanied by angiogenesis. This process creates hypoxia, which activates vascular factors, initiating pathological angiogenesis and further fibrosis. This forms a vicious cycle of ongoing damage and progression. This condition further exacerbates liver injury and may contribute to the development of comorbidities, such as metabolic syndrome as well as hepatocellular carcinoma. Increasing evidence suggests that anti-angiogenic therapy may have beneficial effects on these hepatic disorders and their exacerbation. Therefore, there is a great interest to deepen the knowledge of the molecular mechanisms of natural anti-angiogenic products that could both prevent and control liver diseases. In this review, we focus on the role of major natural anti-angiogenic compounds against steatohepatitis and determine their potential therapeutic benefits in the treatment of liver inflammation caused by an imbalanced diet.

Microglia NLRP3 Inflammasome and Neuroimmune Signaling in Substance Use Disorders

During the last decade, substance use disorders (SUDs) have been increasingly recognized as neuroinflammation-related brain diseases. Various types of abused drugs (cocaine, methamphetamine, alcohol, opiate-like drugs, marijuana, etc.) can modulate the activation status of microglia and neuroinflammation levels which are involved in the pathogenesis of SUDs. Several neuroimmune signaling pathways, including TLR/NF-кB, reactive oxygen species, mitochondria dysfunction, as well as autophagy defection, etc., have been implicated in promoting SUDs. Recently, inflammasome-mediated signaling has been identified as playing critical roles in the microglia activation induced by abused drugs. Among the family of inflammasomes, NOD-, LRR-, and pyrin-domain-containing protein 3 (NLRP3) serves the primary research target due to its abundant expression in microglia. NLRP3 has the capability of integrating multiple external and internal inputs and coordinately determining the intensity of microglia activation under various pathological conditions. Here, we summarize the effects of abused drugs on NLRP3 inflammasomes, as well as others, if any. The research on this topic is still at an infant stage; however, the readily available findings suggest that NLRP3 inflammasome could be a common downstream effector stimulated by various types of abused drugs and play critical roles in determining abused-drug-mediated biological effects through enhancing glia-neuron communications. NLRP3 inflammasome might serve as a novel target for ameliorating the development of SUDs.

A five-cuproptosis-related LncRNA Signature: predicting prognosis, assessing immune function & drug sensitivity in lung squamous cell carcinoma

Lung squamous cell carcinoma has so far lacked effective targets for diagnosis and treatment. In cancer research, long noncoding RNAs (LncRNAs) emerge as novel therapeutic targets and biomarkers. Cuprophosis is a new death type involving multiple biological processes in tumor cells. Here, we aimed to explore whether Cuprophosis-related lncRNAs could be used to predict prognosis, assess immune function, and test drug sensitivity in LUSC patients. The Cancer Genome Map (TCGA) was used to obtain genome and clinical data, and Cuprophosis-relevant genes were found in the literature. A cuproptosis-related lncRNA risk model was built using co-expression analysis, univariate/multivariate Cox regression, and LASSO analysis. The survival analysis was used to assess the model's prognostic value. The univariate and multivariate Cox regression analyses were performed to determine whether risk score, age, gender, or clinical stages could be used as independent prognostic factors. Gene Set Enrichment Analysis and mutation analysis were performed on differentially expressed mRNA between high-risk and low-risk groups. The (TIDE) algorithm was used to conduct immunological functional analysis and drug sensitivity testing. Five cuproptosis-related LncRNAs were identified, and the selected LncRNAs constructed a prognosis model. According to the Kaplan-Meier survival analysis, the overall survival time for patients in the high-risk group was shorter than for those in the low-risk group. For LUSC patients, the risk score serves as an independent prognostic indicator. The GO and KEGG enrichment analysis revealed that the differentially expressed mRNAs between the high- and low-risk groups were enriched in several immune-related processes. The enrichment score of differentially expressed mRNAs in the high-risk group is higher than that of the low-risk group in multiple immune function pathways, including the IFN-γ and MHC I pathways. The Tumor Immune Dysfunction and Exclusion (TIDE) test revealed that the high-risk group was more likely to experience immune escape. The drug sensitivity analysis showed that patients with low-risk ratings were likely to respond to GW441756 and Salubrinal. In contrast, patients with higher risk scores were more responsive to dasatinib and Z-LLNIe CHO. The 5-Cuprophosis-related lncRNA signature can be used to predict prognosis, assess immune function, and test drug sensitivity in LUSC patients.

Role of NLRP3 inflammasome in hepatocellular carcinoma: A double-edged sword

In recent years, the study of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome has become a hot topic, especially its role in various tumors. The incidence of hepatocellular carcinoma is ranked in the top five in China. Hepatocellular carcinoma (HCC) is the predominant and typical form of primary liver cancer. Due to the close relationship between NLRP3 inflammasome and cancers, many studies have investigated its role in HCC. The results suggest that NLRP3 inflammasome participates in both tumor growth inhibition and tumor growth promotion in HCC. Therefore, this review elaborates on the relationship between NLRP3 and HCC and explains its role in HCC. In addition, the potential of NLRP3 as a therapeutic target for cancer therapy is explored, summarizing and classifying impacts of and processes underlying different NLRP3 inflammasome-targeting drugs on HCC.

Lutein attenuates Propionibacterium acnes-induced inflammation by inhibiting pyroptosis of human keratinocyte cells via TLR4/NLRP3/Caspase-1 pathway

BACKGROUND

Previous studies found Propionibacterium acnes (P. acnes) has a strong association with acne inflammation and cell pyroptosis. Because of the various side effects of current acne medicines, it is important to explore alternative drugs with anti-inflammatory activity against P. acnes. we explored the effect of Lutein on P. acnes-induced cell pyroptosis and accelerated the recovery of acne inflammation in vitro and vivo.

METHODS

Lutein was utilized to expose HaCaT keratinocytes, then we reassessed the effect of Lutein on the cell apoptosis, pyroptotic-associated inflammatory factors and catabolic enzymes in heat-killed P. acnes-treated HaCaT cells. Next, living P. acnes was intradermally injected into the right ears of ICR mice to induce mice with acne inflammation, and the effect of Lutein on living P. acnes-induced inflammation was investigated. Moreover, we explored the mechanism of Lutein on TLR4/NLRP3/Caspase-1 pathways by ELISA, immunofluorescence microscopy, and western blot assay.

RESULTS

Heat-killed P. acnes triggered remarkable cell pyroptosis, pyroptotic inflammatory factors and catabolic enzymes in HaCaT cells, including up-regulating interleukin (IL)-1β, IL-18, TNF-α, MMP3, MMP13, ADAMTS4, and ADAMTS5, TLR4, NLRP3, caspase-1, and the ratio of gasdermin D to cleaved gasdermin D, whereas these effects were suppressed by Lutein. In addition, Lutein effectively improved ear redness, swelling, and the expression of TLR4, IL-1β and TNF-α in vivo. Finally, NLRP3 activator (nigericin) increased caspase-1, IL-1β and IL-18 level, while TLR4 inhibitor (TAK-242) significantly blocked this effect in heat-killed P. acnes-treated cells.

CONCLUSIONS

Lutein attenuated P. acnes-caused pyroptosis of HaCaTs and the subsequent acne inflammation via the TLR4/NLRP3/Caspase-1 pathway.

Protective Effect of Polyphenols, Protein, Peptides, and Polysaccharides on Alcoholic Liver Disease: A Review of Research Status and Molecular Mechanisms

Alcoholic liver disease (ALD) has emerged as an important public health problem in the world. The polyphenols, protein, peptides, and polysaccharides have attracted attention for prevention or treatment of ALD. Therefore, this paper reviews the pathogenesis of ALD, the relationship between polyphenols, peptides, polysaccharides, and ALD, and expounds the mechanism of gut microbiota on protecting ALD. It is mainly found that the hydroxyl group of polyphenols endows it with antioxidation to protect ALD. The ALD protection of bioactive peptides is related to amino acid composition. The ALD protection of polysaccharides is related to the primary structure. Meanwhile, polyphenols, protein, peptides, and polysaccharides prevent or treat ALD by antioxidation, anti-inflammatory, antiapoptosis, lipid metabolism, and gut microbiota regulation. This contribution provides updated information on polyphenols, protein, peptides, and polysaccharides in response to ALD, which will not only facilitate the development of novel bioactive components but also the future application of functional food raw materials will be promoted.

Scutellarin prevents acute alcohol-induced liver injury via inhibiting oxidative stress by regulating the Nrf2/HO-1 pathway and inhibiting inflammation by regulating the AKT, p38 MAPK/NF-κB pathways

Alcoholic liver disease (ALD) is the most frequent liver disease worldwide, resulting in severe harm to personal health and posing a serious burden to public health. Based on the reported antioxidant and anti-inflammatory capacities of scutellarin (SCU), this study investigated its protective role in male BALB/c mice with acute alcoholic liver injury after oral administration (10, 25, and 50 mg/kg). The results indicated that SCU could lessen serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and improve the histopathological changes in acute alcoholic liver; it reduced alcohol-induced malondialdehyde (MDA) content and increased glutathione peroxidase (GSH-Px), catalase (CAT), and superoxide dismutase (SOD) activity. Furthermore, SCU decreased tumor necrosis factor-‍α (TNF-‍α), interleukin-6 (IL-6), and IL-‍1β messenger RNA (mRNA) expression levels, weakened inducible nitric oxide synthase (iNOS) activity, and inhibited nucleotide-binding oligomerization domain (NOD)‍-like receptor protein 3 (NLRP3) inflammasome activation. Mechanistically, SCU suppressed cytochrome P450 family 2 subfamily E member 1 (CYP2E1) upregulation triggered by alcohol, increased the expression of oxidative stress-related nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) pathways, and suppressed the inflammation-related degradation of inhibitor of nuclear factor-‍κB (NF-‍κB)‍-‍α (IκBα) as well as activation of NF‍-‍κB by mediating the protein kinase B (AKT) and p38 mitogen-activated protein kinase (MAPK) pathways. These findings demonstrate that SCU protects against acute alcoholic liver injury via inhibiting oxidative stress by regulating the Nrf2/HO-1 pathway and suppressing inflammation by regulating the AKT, p38 MAPK/NF-κB pathways.

The Role of the NLRP3 Inflammasome and Programmed Cell Death in Acute Liver Injury

Acute liver injury (ALI) is a globally important public health issue that, when severe, rapidly progresses to acute liver failure, seriously compromising the life safety of patients. The pathogenesis of ALI is defined by massive cell death in the liver, which triggers a cascade of immune responses. Studies have shown that the aberrant activation of the nod-like receptor protein 3 (NLRP3) inflammasome plays an important role in various types of ALI and that the activation of the NLRP3 inflammasome causes various types of programmed cell death (PCD), and these cell death effectors can in turn regulate NLRP3 inflammasome activation. This indicates that NLRP3 inflammasome activation is inextricably linked to PCD. In this review, we summarize the role of NLRP3 inflammasome activation and PCD in various types of ALI (APAP, liver ischemia reperfusion, CCl₄, alcohol, Con A, and LPS/D-GalN induced ALI) and analyze the underlying mechanisms to provide references for future relevant studies.

Role of Oxidative Stress in Liver Disorders

Oxygen is vital for life as it is required for many different enzymatic reactions involved in intermediate metabolism and xenobiotic biotransformation. Moreover, oxygen consumption in the electron transport chain of mitochondria is used to drive the synthesis of ATP to meet the energetic demands of cells. However, toxic free radicals are generated as byproducts of molecular oxygen consumption. Oxidative stress ensues not only when the production of reactive oxygen species (ROS) exceeds the endogenous antioxidant defense mechanism of cells, but it can also occur as a consequence of an unbalance between antioxidant strategies. Given the important role of hepatocytes in the biotransformation and metabolism of xenobiotics, ROS production represents a critical event in liver physiology, and increasing evidence suggests that oxidative stress contributes to the development of many liver diseases. The present review, which is part of the special issue “Oxidant stress in Liver Diseases”, aims to provide an overview of the sources and targets of ROS in different liver diseases and highlights the pivotal role of oxidative stress in cell death. In addition, current antioxidant therapies as treatment options for such disorders and their limitations for future trial design are discussed.