Apigenin alleviated PA-induced pyroptosis by activating autophagy in hepatocytes

Interplay Between Polyphenols and Autophagy: Insights From an Aging Perspective

The relationship between polyphenols and autophagy, particularly in the context of aging, presents a promising avenue for therapeutic interventions in age-related diseases. A decline in autophagy is associated with aging-related affections, and an increasing number of studies suggest that this enhancement is linked to cellular resilience and longevity. This review delves into the multifaceted roles of autophagy in cellular homeostasis and the potential of polyphenols to modulate autophagic pathways. We revised the most updated literature regarding the modulatory effects of polyphenols on autophagy in cardiovascular, liver, and kidney diseases, highlighting their therapeutic potential. We highlight the role of polyphenols as modulators of autophagy to combat age-related diseases, thus contributing to improving the quality of life in aging populations. A better understanding of the interplay of autophagy between autophagy and polyphenols will help pave the way for future research and clinical applications in the field of longevity medicine.

The therapeutic potential of apigenin against atherosclerosis

Apigenin is a natural flavonoid abundantly found in fruits, vegetables, and medicinal plants. It possesses protective effects against cancer, metabolic syndrome, dyslipidemia, etc. Atherosclerosis, a chronic immune-mediated inflammatory disease, is the underlying cause of coronary heart disease, stroke, and myocardial infarction. Numerous in vivo and in vitro studies have shown a protective effect of apigenin against atherosclerosis, attributed to its antioxidant and anti-inflammatory properties, as well as its antihypertensive effect and regulation of lipid metabolism. This study aimed to review the effects and mechanisms of apigenin against atherosclerosis for the first time. Apigenin displays encouraging results, and this review confirms the potential value of apigenin as a candidate medication for atherosclerosis.

Apigenin as an emerging hepatoprotective agent: current status and future perspectives

Apigenin (C15H10O5, API) is a natural flavonoid widely found in vegetables, fruits, and plants such as celery, oranges, and chamomile. In recent years, API has attracted considerable attention as a dietary supplement due to its low toxicity, non-mutagenic properties and remarkable therapeutic efficacy in various diseases. In particular, evidence from a large number of preclinical studies suggests that API has promising effects in the prevention and treatment of a variety of liver diseases, including multifactorial liver injury, non-alcoholic fatty liver disease/non-alcoholic steatohepatitis, liver fibrosis and liver cancer. This paper provides a comprehensive review of the progress of research into the therapeutic applications of API in liver diseases as of August 2024, based on literature retrieved from databases such as Web of Science, PubMed, CNKI, Google Scholar and ScienceDirect. The hepatoprotective effects of API involve multiple molecular mechanisms, including inhibition of inflammation, alleviation of hepatic oxidative stress, amelioration of insulin resistance, promotion of fatty acid oxidation, inhibition of liver cancer cell proliferation and differentiation, and induction of tumour cell apoptosis. More importantly, signaling pathways such as Nrf2, NF-κB, PI3K/Akt/mTOR, NLRP3, Wnt/β-catenin, TGF-β1/Smad3, AMPK/SREBP, PPARα/γ, MAPKs, and Caspases are identified as key targets through which API exerts its beneficial effects in various liver diseases. Studies on its toxicity and pharmacokinetics indicate that API has low toxicity, is slowly metabolized and excreted in vivo, and has low oral bioavailability. In addition, the paper summarises and discusses the sources, physicochemical properties, new dosage forms, and current challenges and opportunities of API, with the aim of providing direction and rationale for the further development and clinical application of API in the food, pharmaceutical and nutraceutical fields.

Inhibition of Pyroptosis by Hydroxychloroquine as a Neuroprotective Strategy in Ischemic Stroke

Hydroxychloroquine (HCQ), a well-known antimalarial and anti-inflammatory drug, has demonstrated potential neuroprotective effects in ischemic stroke by inhibiting pyroptosis, a programmed cell death associated with inflammation. This study investigates the impact of HCQ on ischemic stroke pathology using both in vivo and in vitro models. In vivo, C57BL/6 mice subjected to middle cerebral artery occlusion (MCAO) were treated with HCQ. Neurological deficits, infarct volume, and the expression of pyroptosis markers were evaluated. The results demonstrated that HCQ significantly improved motor function and reduced infarct volume in the MCAO mouse model. In vitro, BV2 microglial cells exposed to lipopolysaccharide (LPS) and oxygen-glucose deprivation (OGD) were treated with HCQ. Western blot and immunofluorescence analyses revealed that HCQ effectively suppressed the expression of pyroptosis markers GSDMD and NLRP3 in both in vivo and in vitro models. These findings suggest that HCQ mitigates ischemic stroke damage by inhibiting pyroptosis, highlighting its potential as a therapeutic agent for ischemic stroke. This study provides novel insights into the molecular mechanisms by which HCQ exerts its neuroprotective effects, offering a promising new avenue for developing safe, cost-effective, and widely applicable stroke treatments. The potential of HCQ to modulate neuroinflammatory pathways presents a significant advancement in ischemic stroke therapy, emphasizing the importance of targeting pyroptosis in stroke management and the broader implications for treating neuroinflammatory conditions.Significance Statement Ischemic stroke remains a leading cause of disability and death globally, with limited effective treatments. This study reveals that HCQ significantly mitigates ischemic stroke damage by inhibiting pyroptosis, a form of programmed cell death. Using in vivo and in vitro models, HCQ was shown to improve motor function and reduce infarct volume, highlighting its potential as a neuroprotective agent. These findings offer a promising new therapeutic approach for ischemic stroke, emphasizing the importance of targeting pyroptosis in stroke treatment.

MicroRNA 29a alleviates mitochondrial stress in diet-induced NAFLD by inhibiting the MAVS pathway

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder characterized by fat accumulation in the liver. This leads to aggravated hepatocyte inflammation due to impaired mitochondrial function, mitochondrial double-stranded RNA (mt-dsRNA) release, elevated oxidative stress, and reactive oxygen species (ROS) production. MicroRNA-29a (miR-29a) is used to reduce hepatic fibrosis in cases of cholestatic liver damage and lessen the severity of non-alcoholic steatohepatitis in animal studies by influencing mitochondrial protein balance. However, the effectiveness of miR-29a in diminishing mt-dsRNA-induced exacerbation of NAFLD remains poorly understood, particularly in the context of a Western diet (WD). Our results have found that mice with increased miR-29a levels and fed a WD showed notably decreased serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol, and low-density lipoprotein cholesterol levels. They also experienced less weight gain and lower final body and liver weights. In addition, overexpression of miR-29a reduced the severity of fibrosis, alleviated hepatic oxidative stress, misfolded protein aggregates, and the release of mt-dsRNA. Moreover, miR-29a attenuated the innate immune mitochondrial antiviral-signaling protein (MAVS) pathway response. In vitro, the research using HepG2 cells confirmed that miR-29a reduces MAVS expression and decreases the release of mt-dsRNA and superoxide initiated by palmitic acid (PA). Analysis of luciferase activity further established that the specific binding of miR-29a to the 3'UTR of MAVS led to a repression of its expression. In conclusion, these groundbreaking findings underscore the potential of miR-29a in improving the treatment of NAFLD and liver steatofibrosis by inhibiting the MAVS signaling pathway.

Lycopene alleviates age-related cognitive deficit via activating liver-brain fibroblast growth factor-21 signalling

Brain function is linked with many peripheral tissues, including the liver, where hepatic fibroblast growth factor 21 (FGF21) mediates communication between the liver and brain. Lycopene (LYC), a naturally occurring carotenoid, posses multiple health-promoting properties, including neuroprotective function. Here, we investigated the effects of LYC on age-related memory impairment and the relative contribution of liver-brain FGF21 signaling in these process. The results showed that after treatment with LYC for 3 months, brain aging and age-related cognitive deficits were effectively managed. In addition, LYC ameliorated neuronal degeneration, mitochondrial dysfunction and synaptic damage, and promoted synaptic vesicle fusion in 18-month-old mice. Notably, LYC activated liver-brain FGF21 signalling in aging mice. Whereas all these central effects of LYC were negated by blocking FGF21 via i. v. injection of adeno-associated virus in aging mice. Furthermore, recombinant FGF21 elevated mitochondrial ATP levels and enhanced synaptic vesicle fusion in mouse hippocampal HT-22 cells, which promoted neurotransmitter release. Additionally, we co-cultured hepatocytes and neurons in Transwell and found that LYC enhanced hepatocytes' support for neurons. This support included improved cell senescence, enhanced mitochondrial function, and increased axon length in co-cultured neurons. In conclusion, LYC protects against age-related cognitive deficit, partly explained by activating liver-brain FGF21 signalling, hence promoting neurotransmitters release via increasing mitochondrial ATP levels and enhancing synaptic vesicle fusion. These findings revealed that FGF21 could be a potential therapeutical target in nutritional intervention strategies to improve cognitive damage caused by aging and age-related neurodegenerative diseases.

Flavonoids in natural products for the therapy of liver diseases: progress and future opportunities

The liver is the largest, important organ and the site for essential biochemical reactions in the human body. It has the function to detoxify toxic substances and synthesize useful biomolecules. Liver diseases related complications represent a significant source of morbidity and mortality worldwide, creating a substantial economic burden. Oxidative stress, excessive inflammation, and dysregulated energy metabolism significantly contributed to liver diseases. Therefore, discovery of novel therapeutic drugs for the treatment of liver diseases are urgently required. For centuries, flavonoids and their preparations which have the beneficial health effects in chronic diseases have been used to treat various human illnesses. Flavonoids mainly include flavones, isoflavones, flavanols, dihydroflavones, dihydroflavonols, anthocyanins and chalcones. The primary objective of this review is to assess the efficacy and safety of flavonoids, mainly from a clinical point of view and considering clinically relevant end-points. We summarized the recent progress in the research of hepatoprotective and molecular mechanisms of different flavonoids bioactive ingredients and also outlined the networks of underlying molecular signaling pathways. Further pharmacology and toxicology research will contribute to the development of natural products in flavonoids and their derivatives as medicines with alluring prospect in the clinical application.

Sesamin ameliorates nonalcoholic steatohepatitis through inhibiting hepatocyte pyroptosis in vivo and in vitro

Sesamin (Ses) is a natural lignan abundantly present in sesame and sesame oil. Pyroptosis, a newly identified type of pro-inflammatory programmed necrosis, contributes to the development of non-alcoholic steatohepatitis (NASH) when hepatocyte pyroptosis is excessive. In this study, Ses treatment demonstrated an improvement in hepatic damage in mice with high-fat, high-cholesterol diet-induced NASH and palmitate (PA)-treated mouse primary hepatocytes. Notably, we discovered, for the first time, that Ses could alleviate hepatocyte pyroptosis both in vivo and in vitro. Furthermore, treatment with phorbol myristate acetate, a protein kinase Cδ (PKCδ) agonist, increased PKCδ phosphorylation and attenuated the protective effects of Ses against pyroptosis in PA-treated mouse primary hepatocytes. Mechanistically, Ses treatment alleviated hepatocyte pyroptosis in NASH, which was associated with the regulation of the PKCδ/nod-like receptor family CARD domain-containing protein 4/caspase-1 axis. This study introduces a novel concept and target, suggesting the potential use of functional factors in food to alleviate liver damage caused by NASH.

Current Advances in the Regulatory Effects of Bioactive Compounds from Dietary Resources on Nonalcoholic Fatty Liver Disease: Role of Autophagy

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease characterized by lipid metabolic disorder primarily due to sedentary lifestyles and excessive food consumption. However, there are currently no approved and effective drugs available to treat NAFLD. In recent years, research has shown that dietary bioactive compounds, such as polysaccharides, polyphenols, flavones, and alkaloids, have the potential to improve NAFLD by regulating autophagy. However, there is no up-to-date review of research progress in this field. This review aims to systematically summarize and discuss the regulatory effects and molecular mechanisms of dietary bioactive compounds on NAFLD through the modulation of autophagy. The existing research has demonstrated that some dietary bioactive compounds can effectively improve various aspects of NAFLD progression, such as lipid metabolism, insulin resistance (IR), endoplasmic reticulum (ER) stress, oxidative stress, mitochondrial homeostasis, and inflammation. Molecular mechanism studies have revealed that they exert their beneficial effects on NAFLD through autophagy-mediated signaling pathways, predominantly involving transcription factor EB (TFEB), mammalian target of rapamycin (mTOR), adenosine monophosphate-activated protein kinase (AMPK), peroxisome proliferator-activated receptors (PPARs), SIRT, and PTEN-induced kinase 1 (PINK1)/parkin. Furthermore, the challenges and prospects of current research in this field are highlighted. Overall, this review provides valuable insights into the potential treatment of NAFLD using dietary bioactive compounds that can modulate autophagy.

Elaidic acid induced hepatocyte pyroptosis via autophagy-CTSB-NLRP3 pathway

Elaidic acid (EA, C18:1 trans) is a kind of principal Trans fatty acid (TFA) and is widely found in processed food. Pyroptosis is a form of programmed cell death, distinct from apoptosis and traditional necrosis. Excessive pyroptosis could induce body injury and serious inflammation. However, the effect of EA on pyroptosis has not been reported. In the study, we found that EA exposure caused liver damage and hepatocyte pyroptosis by testing GSDMD-N, Caspase 1, IL-18, and IL-1β in mice and HepG2 cells. Further exploring the mechanisms, we found that EA-induced pyroptosis depended on Cathepsin B (CTSB)-mediated NLRP3 inflammasome activation. Cell autophagy was closely related to lysosomes. Our study revealed that EA promoted hepatocyte autophagy, and activated autophagy induced lysosomal membrane permeabilization (LMP) and CTSB leakage. Inhibition of autophagy by 3-MA mitigated the CTSB leak, reduced the activation of the NLRP3 inflammasome, and then attenuated the EA-induced pyroptosis. In summary, these results indicated that EA induced hepatocyte pyroptosis via autophagy-CTSB-NLRP3 inflammasome pathway. The study revealed new insights into the toxicity mechanism of EA.

Apigenin inhibits macrophage pyroptosis through regulation of oxidative stress and the NF-κB pathway and ameliorates atherosclerosis

Pyroptosis plays an important role in inflammatory diseases such as viral hepatitis and atherosclerosis. Apigenin exhibits various bioactivities, particularly anti-inflammation, but its effect on pyroptosis remains unclear. The aim of this study is to investigate the effect of apigenin on pyroptosis and explore its potential against inflammatory diseases. THP-1 macrophages treated by lipopolysaccharides/adenosine 5'-triphosphate were used as the in vitro pyroptosis model. Western blot was used to detect the expression of NLRP3 inflammasome components and key regulators. Immunofluorescence was used to observe ROS production and intracellular location of p65. The potential of apigenin against inflammatory diseases was evaluated using atherosclerotic mice. Plaque progression was observed by pathological staining. Immunofluorescence was used to observe the expression of NLRP3 inflammasome components in plaques. The results showed that apigenin inhibited NLRP3 inflammasome activation. Apigenin reduced ROS overproduction and inhibited p65 nuclear translocation. Additionally, apigenin decreased the expression of NLRP3 inflammasome components in the plaque. Plaque progression was inhibited by apigenin. In conclusion, apigenin exhibited a preventive effect on macrophage pyroptosis by reducing oxidative stress and inhibiting the NF-κB pathway. Apigenin may alleviate atherosclerosis at least partially by inhibiting macrophage pyroptosis. These findings suggest apigenin to be a promising therapeutic agent for inflammatory diseases.

Molecular mechanisms of metabolic disease-associated hepatic inflammation in non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is the leading chronic liver disease worldwide, with a progressive form of non-alcoholic steatohepatitis (NASH). It may progress to advanced liver diseases, including liver fibrosis, cirrhosis, and hepatocellular carcinoma. NAFLD/NASH is a comorbidity of many metabolic disorders such as obesity, insulin resistance, type 2 diabetes, cardiovascular disease, and chronic kidney disease. These metabolic diseases are often accompanied by systemic or extrahepatic inflammation, which plays an important role in the pathogenesis and treatment of NAFLD or NASH. Metabolites, such as short-chain fatty acids, impact the function, inflammation, and death of hepatocytes, the primary parenchymal cells in the liver tissue. Cholangiocytes, the epithelial cells that line the bile ducts, can differentiate into proliferative hepatocytes in chronic liver injury. In addition, hepatic non-parenchymal cells, including liver sinusoidal endothelial cells, hepatic stellate cells, and innate and adaptive immune cells, are involved in liver inflammation. Proteins such as fibroblast growth factors, acetyl-coenzyme A carboxylases, and nuclear factor erythroid 2-related factor 2 are involved in liver metabolism and inflammation, which are potential targets for NASH treatment. This review focuses on the effects of metabolic disease-induced extrahepatic inflammation, liver inflammation, and the cellular and molecular mechanisms of liver metabolism on the development and progression of NAFLD and NASH, as well as the associated treatments.

Regulatory Roles of Flavonoids in Caspase-11 Non-Canonical Inflammasome-Mediated Inflammatory Responses and Diseases

Inflammasomes are multiprotein complexes that activate inflammatory responses by inducing pyroptosis and secretion of pro-inflammatory cytokines. Along with many previous studies on inflammatory responses and diseases induced by canonical inflammasomes, an increasing number of studies have demonstrated that non-canonical inflammasomes, such as mouse caspase-11 and human caspase-4 inflammasomes, are emerging key players in inflammatory responses and various diseases. Flavonoids are natural bioactive compounds found in plants, fruits, vegetables, and teas and have pharmacological properties in a wide range of human diseases. Many studies have successfully demonstrated that flavonoids play an anti-inflammatory role and ameliorate many inflammatory diseases by inhibiting canonical inflammasomes. Others have demonstrated the anti-inflammatory roles of flavonoids in inflammatory responses and various diseases, with a new mechanism by which flavonoids inhibit non-canonical inflammasomes. This review discusses recent studies that have investigated the anti-inflammatory roles and pharmacological properties of flavonoids in inflammatory responses and diseases induced by non-canonical inflammasomes and further provides insight into developing flavonoid-based therapeutics as potential nutraceuticals against human inflammatory diseases.

Apigenin Alleviated High-Fat-Diet-Induced Hepatic Pyroptosis by Mitophagy-ROS-CTSB-NLRP3 Pathway in Mice and AML12 Cells

Apigenin is considered the most-known natural flavonoid and is abundant in a wide variety of fruits and vegetables. A high fat diet (HFD) can induce liver injury and hepatocyte death in multiple ways. Pyroptosis is an innovative type of programmed cell death. Moreover, excessive pyroptosis of hepatocytes leads to liver injury. We used HFD to induce liver cell pyroptosis in C57BL/6J mice in this work. After gavage of apigenin, apigenin can significantly reduce the level of lactate dehydrogenase (LDH) in liver tissue ignited by HFD and reduce the levels of NLRP3 (NOD-like receptor family pyrin domain containing 3), the N-terminal domain of GSDMD (GSDMD-N), cleaved-caspase 1, cathepsin B (CTSB), interleukin-1β (IL-1β) and interleukin-18 (IL-18) protein expression and the colocalization of NLRP3 and CTSB and increase the level of lysosomal associated membrane protein-1 (LAMP-1) protein expression, thus alleviating cell pyroptosis. In a further in vitro mechanism study, we find that palmitic acid (PA) can induce pyroptosis in AML12 cells. After adding apigenin, apigenin can clear the damaged mitochondria through mitophagy and reduce the generation of intracellular reactive oxygen species (ROS), thus alleviating CTSB release caused by lysosomal membrane permeabilization (LMP), reducing the LDH release caused by PA and reducing the levels of NLRP3, GSDMD-N, cleaved-caspase 1, CTSB, IL-1β, and IL-18 protein expression. By adding the mitophagy inhibitor cyclosporin A (CsA), LC3-siRNA, the CTSB inhibitor CA-074 methyl ester (CA-074 Me), and the NLRP3 inhibitor MCC950, the aforementioned results were further confirmed. Therefore, our results show that HFD-fed and PA can damage mitochondria, promote the production of intracellular ROS, enhance the lysosomal membrane permeabilization (LMP), and cause the leakage of CTSB, thus activating the NLRP3 inflammatory body and inducing pyroptosis in C57BL/6J mice and AML12 cells, while apigenin alleviates this phenomenon through the mitophagy-ROS-CTSB-NLRP3 pathway.

Dipsacus and Scabiosa Species-The Source of Specialized Metabolites with High Biological Relevance: A Review

The genera Dipsacus L. and Scabiosa L. of the Caprifoliaceae family are widely distributed in Europe, Asia, and Africa. This work reviews the available literature on the phytochemical profiles, ethnomedicinal uses, and biological activities of the most popular species. These plants are rich sources of many valuable specialized metabolites with beneficial medicinal properties, such as triterpenoid derivatives, iridoids, phenolic acids, and flavonoids. They are also sources of essential oils. The genus Dipsacus has been used for centuries in Chinese and Korean folk medicines to treat bone (osteoporosis) and joint problems (rheumatic arthritis). The Korean Herbal Pharmacopoeia and Chinese Pharmacopoeia include Dipsaci radix, the dried roots of D. asperoides C.Y.Cheng & T.M.Ai. In addition, S. comosa Fisch. ex Roem & Schult. and S. tschiliiensis Grunning are used in traditional Mongolian medicine to treat liver diseases. The current scientific literature data indicate that these plants and their constituents have various biological properties, including inter alia antiarthritic, anti-neurodegenerative, anti-inflammatory, antioxidant, anticancer, and antimicrobial activities; they have also been found to strengthen tendon and bone tissue and protect the liver, heart, and kidney. The essential oils possess antibacterial, antifungal, and insecticidal properties. This paper reviews the key biological values of Dipsacus and Scabiosa species, as identified by in vitro and in vivo studies, and presents their potential pharmacological applications.

Therapeutic interventions target the NLRP3 inflammasome in ulcerative colitis: Comprehensive study

One of the significant health issues in the world is the prevalence of ulcerative colitis (UC). UC is a chronic disorder that mainly affects the colon, beginning with the rectum, and can progress from asymptomatic mild inflammation to extensive inflammation of the entire colon. Understanding the underlying molecular mechanisms of UC pathogenesis emphasizes the need for innovative therapeutic approaches based on identifying molecular targets. Interestingly, in response to cellular injury, the NLR family pyrin domain containing 3 (NLRP3) inflammasome is a crucial part of the inflammation and immunological reaction by promoting caspase-1 activation and the release of interleukin-1β. This review discusses the mechanisms of NLRP3 inflammasome activation by various signals and its regulation and impact on UC.

Autophagy and Glycometabolic Reprograming in the Malignant Progression of Lung Cancer: A Review

Lung cancer is one of the leading causes of cancer-related deaths worldwide. However, there are currently limited treatment options that are widely available to patients with advanced lung cancer, and further research is required to inhibit or reverse disease progression more effectively. In lung and other solid tumor cancers, autophagy and glycometabolic reprograming are critical regulators of malignant development, including proliferation, drug resistance, invasion, and metastasis. To provide a theoretical basis for therapeutic strategies targeting autophagy and glycometabolic reprograming to prevent lung cancer, we review how autophagy and glycometabolism are regulated in the malignant development of lung cancer based on research progress in other solid tumors.