Pellino1 orchestrates gut-kidney axis to perpetuate septic acute kidney injury through activation of STING pathway and NLRP3 inflammasome.

AIMS: Intestinal barrier dysfunction is the initial and propagable factor of sepsis in which acute kidney injury (AKI) has been considered as a common life-threatening complication. Our recent study identifies the regulatory role of Pellino1 in tubular death under inflammatory conditions in vitro. The objective of our current study is to explore the impact of Pellino1 on gut-kidney axis during septic AKI and uncover the molecular mechanism (s) underlying this process. MATERIALS AND METHODS: Immunohistochemistry (IHC) was conducted to evaluate Pellino1 and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) levels in renal biopsies from critically ill patients with a clinical diagnosis of sepsis. Functional and mechanistic studies were characterized in septic models of the Peli-knockout (Peli1-/-) mice by histopathological staining, enzyme-linked immunosorbent assay (ELISA), flow cytometry, immunofluorescence, biochemical detection, CRISPR/Cas9-mediated gene editing and intestinal organoid. KEY FINDINGS: Pellino1, together with NLRP3, are highly expressed in renal biopsies from critically ill patients diagnosed with sepsis and kidney tissues of septic mice. The Peli1-/- mice with sepsis become less prone to develop AKI and have markedly compromised NLRP3 activation in kidney. Loss of Peli1 endows septic mice refractory to intestinal inflammation, barrier permeability and enterocyte apoptosis that requires stimulator of interferons genes (STING) pathway. Administration of STING agonist DMXAA deteriorates AKI and mortality of septic Peli1-/- mice in the presence of kidney-specific NLRP3 reconstitution. SIGNIFICANCE: Our studies suggest that Pellino1 has a principal role in orchestrating gut homeostasis towards renal pathophysiology, thus providing a potential therapeutic target for septic AKI.

[Role of NLRP3 inflammasome in prevention and treatment of cognitive impairment-related diseases and traditional Chinese medicine intervention: a review].

Alzheimer's disease(AD), vascular dementia(VD), and traumatic brain injury(TBI) are more common cognitive impairment diseases characterized by high disability and mortality rates, imposing a heavy burden on individuals and their families. Although AD, VD, and TBI have different specific mechanisms, their pathogenesis is closely related to the nucleotide-binding oligome-rization domain-like receptor protein 3(NLRP3). The NLRP3 inflammasome is involved in neuroinflammatory responses, mediating microglial polarization, regulating the reduction of amyloid ß-protein(Aß) deposition, neurofibrillary tangles(NFTs) formation, autophagy regulation, and maintaining brain homeostasis, and synaptic stability, thereby contributing to the development of AD, VD, and TBI. Previous studies have shown that traditional Chinese medicine(TCM) can alleviate neuroinflammation, promote microglial polarization towards the M2 phenotype, reduce Aß deposition and NFTs formation, regulate autophagy, and maintain brain homeostasis by intervening in NLRP3 inflammasome, hence exerting a role in preventing and treating cognitive impairment-related diseases, reducing psychological and economic pressure on patients, and improving their quality of life. Therefore, this article elucidated the role of NLRP3 inflammasome in AD, VS, and TBI, and provided a detailed summary of the latest research results on TCM intervention in NLRP3 inflammasome for the prevention and treatment of these diseases, aiming to inherit the essence of TCM and provide references and foundations for clinical prevention and treatment of cognitive impairment-related diseases with TCM. Meanwhile, this also offers insights and directions for further research in TCM for the prevention and treatment of cognitive impairment-related diseases.

[Role of NLRP3 inflammasome in heart failure and traditional Chinese medicine intervention: a review].

Heart failure is characterized by high incidence and mortality rates, and the search for effective treatment strategies for heart failure and the improvement of clinical outcomes have always been important research directions. Imbalanced inflammation has been proven to be one of the critical pathological factors in heart failure, positively correlated with adverse events such as impaired cardiac function and myocardial fibrosis. In recent years, studies have confirmed that the activation of the NOD-like receptor thermal protein domain-associated protein 3(NLRP3) inflammasome plays a common regulatory role in the inflammation imbalance induced by various factors in heart failure. Moreover, certain traditional Chinese medicine(TCM) and active components can significantly inhibit the activation of the NLRP3 inflammasome, thereby improving heart failure. This article first overviewed the basic information about the NLRP3 inflammasome, summarized the regulatory mechanisms of the NLRP3 inflammasome in heart failure induced by various factors, introduced recent research progress on TCM and active components that inhibited the NLRP3 inflammasome to improve heart failure, aiming to provide references for innovative drug research in the field of integrated Chinese and western medicine for the prevention and treatment of heart failure.

The interaction of inflammasomes and gut microbiota: novel therapeutic insights.

Inflammasomes are complex platforms for the cleavage and release of inactivated IL-1ß and IL-18 cytokines that trigger inflammatory responses against damage-associated molecular patterns (DAMPs) or pathogen-associated molecular patterns (PAMPs). Gut microbiota plays a pivotal role in maintaining gut homeostasis. Inflammasome activation needs to be tightly regulated to limit aberrant activation and bystander damage to the host cells. Several types of inflammasomes, including Node-like receptor protein family (e.g., NLRP1, NLRP3, NLRP6, NLRP12, NLRC4), PYHIN family, and pyrin inflammasomes, interact with gut microbiota to maintain gut homeostasis. This review discusses the current understanding of how inflammasomes and microbiota interact, and how this interaction impacts human health. Additionally, we introduce novel biologics and antagonists, such as inhibitors of IL-1ß and inflammasomes, as therapeutic strategies for treating gastrointestinal disorders when inflammasomes are dysregulated or the composition of gut microbiota changes.

Advances in the mechanism of inflammasomes activation in herpes virus infection.

Herpesviruses, prevalent DNA viruses with a double-stranded structure, establish enduring infections and play a part in various diseases. Despite their deployment of multiple tactics to evade the immune system, both localized and systemic inflammatory responses are triggered by the innate immune system's recognition of them. Recent progress has offered more profound understandings of the mechanisms behind the activation of the innate immune system by herpesviruses, specifically through inflammatory signaling. This process encompasses the initiation of an intracellular nucleoprotein complex, the inflammasome associated with inflammation.Following activation, proinflammatory cytokines such as IL-1ß and IL-18 are released by the inflammasome, concurrently instigating a programmed pathway for cell death. Despite the structural resemblances between herpesviruses, the distinctive methods of inflammatory activation and the ensuing outcomes in diseases linked to the virus exhibit variations.The objective of this review is to emphasize both the similarities and differences in the mechanisms of inflammatory activation among herpesviruses, elucidating their significance in diseases resulting from these viral infections.Additionally, it identifies areas requiring further research to comprehensively grasp the impact of this crucial innate immune signaling pathway on the pathogenesis of these prevalent viruses.

Repetitive transcranial magnetic stimulation ameliorates cognitive deficits in mice with radiation-induced brain injury by attenuating microglial pyroptosis and promoting neurogenesis via BDNF pathway.

BACKGROUND: Radiation-induced brain injury (RIBI) is a common and severe complication during radiotherapy for head and neck tumor. Repetitive transcranial magnetic stimulation (rTMS) is a novel and non-invasive method of brain stimulation, which has been applied in various neurological diseases. rTMS has been proved to be effective for treatment of RIBI, while its mechanisms have not been well understood. METHODS: RIBI mouse model was established by cranial irradiation, K252a was daily injected intraperitoneally to block BDNF pathway. Immunofluorescence staining, immunohistochemistry and western blotting were performed to examine the microglial pyroptosis and hippocampal neurogenesis. Behavioral tests were used to assess the cognitive function and emotionality of mice. Golgi staining was applied to observe the structure of dendritic spine in hippocampus. RESULTS: rTMS significantly promoted hippocampal neurogenesis and mitigated neuroinflammation, with ameliorating pyroptosis in microglia, as well as downregulation of the protein expression level of NLRP3 inflammasome and key pyroptosis factor Gasdermin D (GSDMD). BDNF signaling pathway might be involved in it. After blocking BDNF pathway by K252a, a specific BDNF pathway inhibitor, the neuroprotective effect of rTMS was markedly reversed. Evaluated by behavioral tests, the cognitive dysfunction and anxiety-like behavior were found aggravated with the comparison of mice in rTMS intervention group. Moreover, the level of hippocampal neurogenesis was found to be attenuated, the pyroptosis of microglia as well as the levels of GSDMD, NLRP3 inflammasome and IL-1ß were upregulated. CONCLUSION: Our study indicated that rTMS notably ameliorated RIBI-induced cognitive disorders, by mitigating pyroptosis in microglia and promoting hippocampal neurogenesis via mediating BDNF pathway.

Nod-like receptor protein 3 inflammasome-mediated pyroptosis contributes to chronic NaAsO2 exposure-induced fibrotic changes and dysfunction in the liver of SD rats.

The metalloid arsenic, known for its toxic properties, is widespread presence in the environment. Our previous research has confirmed that prolonged exposure to arsenic can lead to liver fibrosis injury in rats, while the precise pathogenic mechanism still requires further investigation. In the past few years, the Nod-like receptor protein 3 (NLRP3) inflammasome has been found to play a pivotal role in the occurrence and development of liver injury. In this study, we administered varying doses of sodium arsenite (NaAsO2) and 10 mg/kg.bw MCC950 (a particular tiny molecular inhibitor targeting NLRP3) to Sprague-Dawley (SD) rats for 36 weeks to explore the involvement of NLRP3 inflammasome in NaAsO2-induced liver injury. The findings suggested that prolonged exposure to NaAsO2 resulted in pyroptosis in liver tissue of SD rats, accompanied by the fibrotic injury, extracellular matrix (ECM) deposition and liver dysfunction. Moreover, long-term NaAsO2 exposure activated NLRP3 inflammasome, leading to the release of pro-inflammatory cytokines in liver tissue. After treatment with MCC950, the induction of NLRP3-mediated pyroptosis and release of pro-inflammatory cytokines were significantly attenuated, leading to a decrease in the severity of liver fibrosis and an improvement in liver function. To summarize, those results clearly indicate that hepatic fibrosis and liver dysfunction induced by NaAsO2 occur through the activation of NLRP3 inflammasome-mediated pyroptosis, shedding new light on the potential mechanisms underlying arsenic-induced liver damage.

The NLR family of innate immune and cell death sensors.

Nucleotide-binding oligomerization domain (NOD)-like receptors, also known as nucleotide-binding leucine-rich repeat receptors (NLRs), are a family of cytosolic pattern recognition receptors that detect a wide variety of pathogenic and sterile triggers. Activation of specific NLRs initiates pro- or anti-inflammatory signaling cascades and the formation of inflammasomes-multi-protein complexes that induce caspase-1 activation to drive inflammatory cytokine maturation and lytic cell death, pyroptosis. Certain NLRs and inflammasomes act as integral components of larger cell death complexes-PANoptosomes-driving another form of lytic cell death, PANoptosis. Here, we review the current understanding of the evolution, structure, and function of NLRs in health and disease. We discuss the concept of NLR networks and their roles in driving cell death and immunity. An improved mechanistic understanding of NLRs may provide therapeutic strategies applicable across infectious and inflammatory diseases and in cancer.

Inflammatory Consequences: Hepatitis C Virus-Induced Inflammasome Activation and Pyroptosis.

Hepatitis C virus (HCV), despite the availability of effective direct-acting antivirals (DAAs) that clear the virus from >95% of individuals treated, continues to cause significant health care burden due to disease progression that can lead to fibrosis, cirrhosis, and/or hepatocellular carcinoma. The fact that some people who are treated with DAAs still go on to develop worsening liver disease warrants further study into the immunopathogenesis of HCV. Many viral infections, including HCV, have been associated with activation of the inflammasome/pyroptosis pathway. This inflammatory cell death pathway ultimately results in cell lysis and release of inflammatory cytokines, IL-18 and IL-1ß. This review will report on studies that investigated HCV and inflammasome activation/pyroptosis. This includes clinical in vivo data showing elevated pyroptosis-associated cytokines in the blood of individuals living with HCV, studies of genetic associations of pyroptosis-related genes and development of liver disease, and in vitro studies aimed at understanding the mechanism of pyroptosis induced by HCV. Finally, we discuss major gaps in understanding and outstanding questions that remain in the field of HCV-induced pyroptosis.

Truncating NFKB1 variants cause combined NLRP3 inflammasome activation and type I interferon signaling and predispose to necrotizing fasciitis.

In monogenic autoinflammatory diseases, mutations in genes regulating innate immune responses often lead to uncontrolled activation of inflammasome pathways or the type I interferon (IFN-I) response. We describe a mechanism of autoinflammation potentially predisposing patients to life-threatening necrotizing soft tissue inflammation. Six unrelated families are identified in which affected members present with necrotizing fasciitis or severe soft tissue inflammations. Exome sequencing reveals truncating monoallelic loss-of-function variants of nuclear factor κ light-chain enhancer of activated B cells (NFKB1) in affected patients. In patients' macrophages and in NFKB1-variant-bearing THP-1 cells, activation increases both interleukin (IL)-1ß secretion and IFN-I signaling. Truncation of NF-κB1 impairs autophagy, accompanied by the accumulation of reactive oxygen species and reduced degradation of inflammasome receptor nucleotide-binding oligomerization domain, leucine-rich repeat-containing protein 3 (NLRP3), and Toll/IL-1 receptor domain-containing adaptor protein inducing IFN-ß (TRIF), thus leading to combined excessive inflammasome and IFN-I activity. Many of the patients respond to anti-inflammatory treatment, and targeting IL-1ß and/or IFN-I signaling could represent a therapeutic approach for these patients.

Dicoumarol attenuates NLRP3 inflammasome activation to inhibit inflammation and fibrosis in knee osteoarthritis.

Knee osteoarthritis (KOA) is a major cause of disability in elderly individuals. Dicoumarol is a coumarin­like compound derived from sweet clover [Melilotus officinalis (L.) Pall]. It has been suggested that dicoumarol exhibits various types of pharmacological activities, including anticoagulant, antitumor and antibacterial effects. Due to its various biological activities, dicoumarol has a potential protective effect against OA. Therefore, the present study aimed to assess the effects of dicoumarol on knee osteoarthritis. In the present study, dicoumarol was found to protect rat synoviocytes from lipopolysaccharide (LPS)­induced cell apoptosis. Western blot analysis showed that dicoumarol significantly reduced the protein expression levels of fibrosis­related markers and inflammatory cytokines (Tgfb, Timp, Col1a, Il1b and Il18). The inhibitory rates of these proteins were all >50% (P<0.01) compared with those in the LPS and ATP­induced group. Consistently, the mRNA expression levels of these markers and cytokines were decreased to normal levels by dicoumarol after the treatment of rat synovial fibroblasts with LPS and ATP. Mechanistic studies demonstrated that dicoumarol did not affect NF­κB signaling, but it did directly interact with NOD­like receptor protein 3 (NLRP3) to promote its protein degradation, which could be reversed by MG132, but not NH4Cl. The protein half­life of NLRP3 was accelerated from 26.1 to 4.3 h by dicoumarol. Subsequently, dicoumarol could alleviate KOA in vivo; knee joint diameter was decreased from 11.03 to 9.93 mm. Furthermore, the inflammation and fibrosis of the knee joints were inhibited in rats. In conclusion, the present findings demonstrated that dicoumarol could impede the progression of KOA by inhibiting NLRP3 activation, providing a potential treatment strategy for KOA.

Cardioprotective Potential of Cymbopogon citratus Essential Oil against Isoproterenol-induced Cardiomyocyte Hypertrophy: Possible Involvement of NLRP3 Inflammasome and Oxidative Phosphorylation Complex Subunits.

OBJECTIVE: Cymbopogon citratus (DC.) Stapf is a medicinal and edible herb that is widely used for the treatment of gastric, nervous and hypertensive disorders. In this study, we investigated the cardioprotective effects and mechanisms of the essential oil, the main active ingredient of Cymbopogon citratus, on isoproterenol (ISO)-induced cardiomyocyte hypertrophy. METHODS: The compositions of Cymbopogon citratus essential oil (CCEO) were determined by gas chromatography-mass spectrometry. Cardiomyocytes were pretreated with 16.9 µg/L CCEO for 1 h followed by 10 µmol/L ISO for 24 h. Cardiac hypertrophy-related indicators and NLRP3 inflammasome expression were evaluated. Subsequently, transcriptome sequencing (RNA-seq) and target verification were used to further explore the underlying mechanism. RESULTS: Our results showed that the CCEO mainly included citronellal (45.66%), geraniol (23.32%), and citronellol (10.37%). CCEO inhibited ISO-induced increases in cell surface area and protein content, as well as the upregulation of fetal gene expression. Moreover, CCEO inhibited ISO-induced NLRP3 inflammasome expression, as evidenced by decreased lactate dehydrogenase content and downregulated mRNA levels of NLRP3, ASC, CASP1, GSDMD, and IL-1ß, as well as reduced protein levels of NLRP3, ASC, pro-caspase-1, caspase-1 (p20), GSDMD-FL, GSDMD-N, and pro-IL-1ß. The RNA-seq results showed that CCEO inhibited the increase in the mRNA levels of 26 oxidative phosphorylation complex subunits in ISO-treated cardiomyocytes. Our further experiments confirmed that CCEO suppressed ISO-induced upregulation of mt-Nd1, Sdhd, mt-Cytb, Uqcrq, and mt-Atp6 but had no obvious effects on mt-Col expression. CONCLUSION: CCEO inhibits ISO-induced cardiomyocyte hypertrophy through the suppression of NLRP3 inflammasome expression and the regulation of several oxidative phosphorylation complex subunits.

Adipose tissue IL-18 production is independent of caspase-1 and caspase-11.

BACKGROUND: Inflammation in adipose tissue, resulting from imbalanced caloric intake and energy expenditure, contributes to the metabolic dysregulation observed in obesity. The production of inflammatory cytokines, such as IL-1ß and IL-18, plays a key role in this process. While IL-1ß promotes insulin resistance and diabetes, IL-18 regulates energy expenditure and food intake. Previous studies have suggested that caspase-1, activated by the Nlrp3 inflammasome in response to lipid excess, mediates IL-1ß production, whereas activated by the Nlrp1b inflammasome in response to energy excess, mediates IL-18 production. However, this has not been formally tested. METHODS: Wild-type and caspase-1-deficient Balb/c mice, carrying the Nlrp1b1 allele, were fed with regular chow or a high-fat diet for twelve weeks. Food intake and mass gain were recorded weekly. At the end of the twelve weeks, glucose tolerance and insulin resistance were evaluated. Mature IL-18 protein levels and the inflammatory process in the adipose tissue were determined. Fasting lipid and cytokine levels were quantified in the sera of the different experimental groups. RESULTS: We found that IL-18 production in adipose tissue is independent of caspase-1 activity, regardless of the metabolic state, while Nlrp3-mediated IL-1ß production remains caspase-1 dependent. Additionally, caspase-1 null Balb/c mice did not develop metabolic abnormalities in response to energy excess from the high-fat diet. CONCLUSION: Our findings suggest that IL-18 production in the adipose tissue is independent of Nlrp3 inflammasome and caspase-1 activation, regardless of caloric food intake. In contrast, Nlrp3-mediated IL-1ß production is caspase-1 dependent. These results provide new insights into the mechanisms underlying cytokine production in the adipose tissue during both homeostatic conditions and metabolic stress, highlighting the distinct roles of caspase-1 and the Nlrp inflammasomes in regulating inflammatory responses.

[Research progress on pyroptosis in liver diseases].

Pyroptosis is a newly discovered kind of cell death modality that, due to its association with innate immunity, plays a crucial role in cytolysis and inflammatory cytokine release during host defense against infection. In recent years, studies have shown that pyroptosis plays an important role in the occurrence and development of liver diseases. This article introduces and elaborates on the most recent research progress on pyroptosis in liver diseases based on the morphological features, molecular and pathophysiological mechanisms.

The heavy subunit of ferritin stimulates NLRP3 inflammasomes in hepatic stellate cells through ICAM-1 to drive hepatic inflammation.

Serum ferritin concentrations increase during hepatic inflammation and correlate with the severity of chronic liver disease. Here, we report a molecular mechanism whereby the heavy subunit of ferritin (FTH) contributes to hepatic inflammation. We found that FTH induced activation of the NLRP3 inflammasome and secretion of the proinflammatory cytokine interleukin-1ß (IL-1ß) in primary rat hepatic stellate cells (HSCs) through intercellular adhesion molecule-1 (ICAM-1). FTH-ICAM-1 stimulated the expression of Il1b, NLRP3 inflammasome activation, and the processing and secretion of IL-1ß in a manner that depended on plasma membrane remodeling, clathrin-mediated endocytosis, and lysosomal destabilization. FTH-ICAM-1 signaling at early endosomes stimulated Il1b expression, implying that this endosomal signaling primed inflammasome activation in HSCs. In contrast, lysosomal destabilization was required for FTH-induced IL-1ß secretion, suggesting that lysosomal damage activated inflammasomes. FTH induced IL-1ß production in liver slices from wild-type mice but not in those from Icam1-/- or Nlrp3-/- mice. Thus, FTH signals through its receptor ICAM-1 on HSCs to activate the NLRP3 inflammasome. We speculate that this pathway contributes to hepatic inflammation, a key process that stimulates hepatic fibrogenesis associated with chronic liver disease.

[Mechanism of traditional Chinese medicine in regulating NLRP3 inflammasomes to alleviate renal interstitial fibrosis in diabetic nephropathy: a review].

Diabetic nephropathy(DN), a progressive chronic kidney disease(CKD) induced by diabetes mellitus, is the main cause of end-stage renal disease. Renal interstitial fibrosis(RIF) is an irreversible factor in the progression and deterioration of the renal function in DN. Chronic inflammation has become a key link in the pathogenesis of DN-RIF. The NOD-like receptor thermal protein domain associated protein 3(NLRP3) inflammasome is an important inflammatory regulator regulated by a variety of signals. It promotes the production of pro-inflammatory cytokines and induces renal inflammatory cell infiltration to participate in the process of renal fibrosis, demonstrating a complex mechanism of action. In view of the important role of NLRP3 inflammasomes in the prevention and treatment of DN-RIF, a large number of experimental studies have demonstrated that traditional Chinese medicine(TCM) can reduce the inflammation by regulating the pathways involving NLRP3 inflammasome, thereby slowing down the progression of DN-RIF and improving the renal function. This paper reviews the relationship between NLRP3 inflammasomes and DN-RIF, and the research progress in the mechanism of TCM intervention in NLRP3 inflammasomes to alleviate DN-RIF, aiming to provide new ideas for the targeted treatment of DN-RIF.

Modulation and Determination of the Status of Inflammasomes in Leishmania-Infected Macrophages.

Leishmania, an intra-macrophage kinetoplastid parasite, modulates a vast array of defensive mechanisms of the host macrophages to create a comfortable environment for their survival. When the host encounters intracellular pathogens, a multimeric protein complex called NLRP3 inflammasome gets turned on, leading to caspase-1 activation-mediated maturation of IL-1ß from its pro-form. However, Leishmania often manages to neutralize inflammasome activation by manipulating negative regulatory molecules of the host itself. Exhaustion of NLRP3 and pro-IL-1ß result from decreased NF-κB activity in infection, which was attributed to increased expression of A20, a negative regulator of NF-κB signalling. Moreover, reactive oxygen species, another key requirement for inflammasome activation, are inhibited by mitochondrial uncoupling protein 2 (UCP2) which is upregulated by Leishmania. Inflammasome activation is a complex event and procedures involved in monitoring inflammasome activation need to be accurate and error-free. In this chapter, we summarize the protocol that includes various experimental procedures required for the determination of the status of inflammasomes in Leishmania-infected macrophages.

Mitochondria-targeted reactive oxygen species blockor SS-31 blocks hepatic stellate cell activation and alleviates hepatic fibrosis by regulating NLRP3 inflammasomes.

This study aimed to elucidate the effect of mitochondria-targeted reactive oxygen species (ROS) blockor SS-31 on hepatic stellate cells (HSC) activation during liver fibrosis. TGF-ß1 was employed to induce HSC activation, while MitoSOX Red was utilized to assess the presence of mitochondrial ROS. The mitochondrial membrane potential (MMP) was measured using the JC-1 probe, and the ATP level was determined using a specific kit. The proliferation of HSCs was assessed using CCK-8 and colony formation assays, whereas flow cytometry was employed to detect HSC apoptosis. Fibrotic markers (COL1A1 and α-SMA) and NLRP3 inflammasome components (NLRP3, caspase-1, and ASC) were analyzed via Western blotting. Liver fibrosis was induced in mice using CCl4, and subsequently, histopathological changes were observed through HE staining and Masson staining. In TGF-ß1-activated HSCs, mitochondrial ROS expression increased, MMP and ATP content decreased, indicating mitochondrial damage. After TGF-ß1 induction, HSC proliferation increased, apoptosis decreased, and COL1A1, α-SMA, and NLRP3 inflammasome protein expression increased. After SS-31 treatment, mitochondrial ROS expression decreased, MMP recovered, ATP level increased, HSC proliferation decreased, apoptosis increased, and the expressions of COL1A1, α-SMA, and NLRP3 inflammasome decreased. NLRP3 blockor MCC950 treatment blocked HSC activation. CCL4-induced liver fibrosis mice had inflammatory cell infiltration and significant collagen fiber deposition in the liver. After SS-31 treatment, liver inflammation and collagen deposition were significantly reduced. SS-31, as a mitochondria-targeted ROS blockor, can block HSC activation by regulating the NLRP3 inflammasome, thereby alleviating liver fibrosis.

Vitamin D Mitigates Hepatic Fat Accumulation and Inflammation and Increases SIRT1/AMPK Expression in AML-12 Hepatocytes.

Emerging evidence has demonstrated a strong correlation between vitamin D status and fatty liver disease. Aberrant hepatic fat infiltration contributes to oxidant overproduction, promoting metabolic dysfunction, and inflammatory responses. Vitamin D supplementation might be a good strategy for reducing hepatic lipid accumulation and inflammation in non-alcoholic fatty liver disease and its associated diseases. This study aimed to investigate the role of the most biologically active form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D), in hepatic fat accumulation and inflammation in palmitic acid (PA)-treated AML-12 hepatocytes. The results indicated that treatment with 1,25(OH)2D significantly decreased triglyceride contents, lipid peroxidation, and cellular damage. In addition, mRNA levels of apoptosis-associated speck-like CARD-domain protein (ASC), thioredoxin-interacting protein (TXNIP), NOD-like receptor family pyrin domain-containing 3 (NLRP3), and interleukin-1ß (IL-1ß) involved in the NLRP3 inflammasome accompanied by caspase-1 activity and IL-1ß expression were significantly suppressed by 1,25(OH)2D in PA-treated hepatocytes. Moreover, upon PA exposure, 1,25(OH)2D-incubated AML-12 hepatocytes showed higher sirtulin 1 (SIRT1) expression and adenosine monophosphate-activated protein kinase (AMPK) phosphorylation. A SIRT1 inhibitor alleviated the beneficial effects of 1,25(OH)2D on PA-induced hepatic fat deposition, IL-1ß expression, and caspase-1 activity. These results suggest that the favorable effects of 1,25(OH)2D on hepatic fat accumulation and inflammation may be, at least in part, associated with the SIRT1.

Tau induces inflammasome activation and microgliosis through acetylating NLRP3.

BACKGROUND: Alzheimer's disease (AD) and related Tauopathies are characterised by the pathologically hyperphosphorylated and aggregated microtubule-associated protein Tau, which is accompanied by neuroinflammation mediated by activated microglia. However, the role of Tau pathology in microglia activation or their causal relationship remains largely elusive. METHODS: The levels of nucleotide-binding oligomerisation domain (NOD)-like receptor pyrin domain containing 3 (NLRP3) acetylation and inflammasome activation in multiple cell models with Tau proteins treatment, transgenic mice with Tauopathy, and AD patients were measured by Western blotting and enzyme-linked immunosorbent assay. In addition, the acetyltransferase activity of Tau and NLRP3 acetylation sites were confirmed using the test-tube acetylation assay, co-immunoprecipitation, immunofluorescence (IF) staining, mass spectrometry and molecular docking. The Tau-overexpressing mouse model was established by overexpression of human Tau proteins in mouse hippocampal CA1 neurons through the adeno-associated virus injection. The cognitive functions of Tau-overexpressing mice were assessed in various behavioural tests, and microglia activation was analysed by Iba-1 IF staining and [18F]-DPA-714 positron emission tomography/computed tomography imaging. A peptide that blocks the interaction between Tau and NLRP3 was synthesised to determine the in vitro and in vivo effects of Tau-NLRP3 interaction blockade on NLRP3 acetylation, inflammasome activation, microglia activation and cognitive function. RESULTS: Excessively elevated NLRP3 acetylation and inflammasome activation were observed in 3xTg-AD mice, microtubule-associated protein Tau P301S (PS19) mice and AD patients. It was further confirmed that mimics of 'early' phosphorylated-Tau proteins which increase at the initial stage of diseases with Tauopathy, including TauT181E, TauS199E, TauT217E and TauS262E, significantly promoted Tau-K18 domain acetyltransferase activity-dependent NLRP3 acetylation and inflammasome activation in HEK293T and BV-2 microglial cells. In addition, Tau protein could directly acetylate NLRP3 at the K21, K22 and K24 sites at its PYD domain and thereby induce inflammasome activation in vitro. Overexpression of human Tau proteins in mouse hippocampal CA1 neurons resulted in impaired cognitive function, Tau transmission to microglia and microgliosis with NLRP3 acetylation and inflammasome activation. As a targeted intervention, competitive binding of a designed Tau-NLRP3-binding blocking (TNB) peptide to block the interaction of Tau protein with NLRP3 inhibited the NLRP3 acetylation and downstream inflammasome activation in microglia, thereby alleviating microglia activation and cognitive impairment in mice. CONCLUSIONS: In conclusion, our findings provide evidence for a novel role of Tau in the regulation of microglia activation through acetylating NLRP3, which has potential implications for early intervention and personalised treatment of AD and related Tauopathies.