NLRP3-mediated Inflammation Research Articles

NLRP3 is a BMI-independent mediator of stable COPD

PurposeThe inflammatory response in animal models of chronic obstructive pulmonary disease (COPD) is activated by the NLR-family-pyrin-domain-containing-3 (NLRP3) inflammasome pathway, which is also known to play a role in obesity-related inflammation. The NLRP3/caspase-1/interleukin (IL)-1β pathway might be involved in the progression of COPD with increasing body mass index. To our knowledge, no previous studies have explored the role of NLRP3 inflammasome markers in linking COPD and obesity. Here, we aim to investigate this potential connection by examining levels of NLRP3, caspase-1, IL-1β, and IL-17A and to provide additional data on the expression of these molecules in relation to smoking status and COPD severity.MethodsA case‒control study was conducted between July 2020 and March 2023. Peripheral blood mononuclear cells were isolated, and total RNA was extracted for real-time quantitative polymerase chain reaction (qPCR) analysis to measure the expression levels of inflammasome molecules.Results29 subjects who were diagnosed with stable COPD and 32 controls were included in the data analysis. NLRP3 and IL-17A but not caspase-1 or IL-1β expression was significantly greater in the COPD group than in the control group. We detected a significant increase in NLRP3 levels in the smoker COPD group (p = 0.009) and nonsmoker COPD group (p = 0.045) compared with those in the nonsmoker control group. There was no significant correlation between BMI and the inflammasome markers.ConclusionAs proinflammatory biomarkers, NLRP3 and IL-17A are prominent in stable COPD patients. Smoking may trigger NLRP3-mediated inflammation in stable COPD patients. The expression levels of NLRP3 inflammasome molecules did not differ in terms of disease severity or BMI.Graphical

Exploring the health benefits of food bioactive compounds from a perspective of NLRP3 inflammasome activation: an insight review.

The food industry has been focusing on food bioactive compounds with multiple physiological and immunological properties that benefit human health. These bioactive compounds, including polyphenols, flavonoids, and terpenoids, have great potential to limit inflammatory responses especially NLRP3 inflammasome activation, which is a key innate immune platform for inflammation. Current studies have revealed numerous food bioactive compounds with promising activities for unraveling immune metabolic disorders and excessive inflammatory responses by directly and indirectly regulating the NLRP3 inflammasome activation. This review explores the food hazards, including microbial and abiotic factors, that may trigger NLRP3-mediated illnesses and inflammation. It also highlights bioactive compounds in food that can suppress NLRP3 inflammasome activation through various mechanisms, linking its activation and inhibition to different pathways. Especially, this review provided further insight into NLRP3-related targets where food bioactive compounds can interact to block the NLRP3 inflammasome activation process, as well as mechanisms on how these compounds facilitate inactivation processes.

Why do microplastics aggravate cholestatic liver disease? The NLRP3-mediated intestinal barrier integrity damage matter.

Microplastics (MPs) are becoming a significant environmental and public health concern because they are present in freshwater and marine environments and are ingested by living organisms. Cholestatic liver disease (CLD) is closely related to intestinal homeostasis, but there are no data investigating the effects of MPs on CLD. In this study, we used Mdr2-/- mice (a model of CLD) to investigate the effects of polystyrene microplastics (PS-MPs, 0.5 μm) on CLD and the underlying mechanisms. Our data revealed that, compared with Mdr2-/- mice, PS-MPs (200 μg/day)-challenged Mdr2-/- mice presented more severe collagen deposition, infiltration of inflammatory cells in liver sections and higher alkaline phosphatase (ALP)/γ-glutamyltransferase (γ-GGT) concentrations in the serum. Furthermore, the number of mucous cells in the colonic tissues of mice with CLD was strongly inhibited by PS-MPs, accompanied by the downregulation of intestinal barrier integrity proteins (ZO-1, Occludin and Claudin-1). Through correlation analysis to further verify the connection between ALP/γ-GGT levels and intestinal barrier integrity genes, as well as a significant positive correlation with IL-1β after PS-MPs exposure. Our results also revealed that PS-MPs exposure accelerated the NOD-like receptor protein 3 (NLRP3)-associated inflammatory response in the colon but did not affect NLRP3 expression in the livers of Mdr2-/- mice. Further study confirmed that the inhibition of NLRP3 by the MCC950 inhibitor abrogated the exacerbating effects of PS-MPs on hepatobiliary injury and intestinal barrier integrity damage. These findings provide the first evidence that NLRP3-mediated inflammation is an important participant in intestinal barrier integrity damage crosstalk that drives CLD under MPs exposure and identify NLRP3 as a potential therapeutic target.

1,25-Dihydroxyvitamin D3 protects against placental inflammation by suppressing NLRP3-mediated IL-1β production via Nrf2 signaling pathway in preeclampsia

BackgroundMaternal vitamin D deficiency is associated with an increased risk of preeclampsia, a potentially life-threatening multi-system disorder specific to human pregnancy. Placental trophoblast dysfunction is a key factor in the development of preeclampsia, and the activation of NOD-like receptor protein 3 (NLRP3) inflammasome may play a crucial role in this process. Previous studies have suggested that vitamin D can exert beneficial effects by suppressing inflammasome activation, but the underlying mechanism has not been fully elucidated. This study aims to explore the protective effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on the placenta and to investigate the mechanisms by which 1,25(OH)2D3 attenuates NLRP3 inflammasome activation in a rat model of preeclampsia and hypoxia-cultured placental trophoblast cells. ResultsOur findings demonstrated that supplementation of rats with 1,25(OH)2D3 mitigated placental inflammation and prevented multi-organ dysfunction associated with preeclampsia. Treatment with 1,25(OH)2D3 inhibited inflammasome-mediated inflammation in trophoblast cells via its receptor VDR by reducing the expression of NLRP3, caspase-1, and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), decreasing IL-1β production, reducing mitochondrial reactive oxygen species generation, and enhancing the expression and enzymatic activity of Cu/Zn-superoxide dismutase (SOD). Mechanistically, 1,25(OH)2D3 upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) signaling, subsequently suppressing NLRP3-mediated IL-1β overproduction in trophoblast cells. ConclusionsOur study indicates that 1,25(OH)2D3 inhibits NLRP3-mediated inflammation in trophoblast cells during preeclampsia by stimulating the Nrf2 signaling pathway and inhibiting oxidative stress.

Conjugated bile acids alleviate acute pancreatitis through inhibition of TGR5 and NLRP3 mediated inflammation

IntroductionSevere acute pancreatitis (SAP) is a crucial gastrointestinal disease characterized by systemic inflammatory responses and persistent multiple organ failure. The role of bile acids (BAs) in diverse inflammatory diseases is increasingly recognized as crucial, but the underlying role of BA conjugation remains elusive.ObjectivesOur study aim to investigate the potential role of conjugated bile acids in SAP and reveal the molecular mechanisms underlying its regulatory effects. We hypothesized that taurochenodeoxycholic acid (TCDCA) and glycochenodeoxycholic acid (GCDCA) could protect SAP through inhibiting the activation of NLRP3 inflammasomes via the TGR5 pathway in macrophages.MethodsTo test our hypothesis, we used BA-CoA: amino acid N-acyltransferase knockout (Baat−/−) mice and established SAP mouse models using caerulein- and sodium taurocholate- induced. We utilized a range of methods, including pathology sections, qRT-PCR, immunofluorescence, Western blotting, and ELISA, to identify the mechanisms of regulation.ResultsBA-CoA: Amino acid N-acyltransferase knockout (Baat−/−) mice significantly exacerbated pancreatitis by increasing pancreatic and systemic inflammatory responses and pancreatic damage in SAP mouse models. Moreover, the serum TCDCA levels in Baat−/− mice were lower than those in wild-type (WT) mice with or without SAP, and GCDCA and TCDCA showed stronger anti-inflammatory effects than chenodeoxycholic acid (CDCA) in vitro. TCDCA treatment alleviated SAP in a Takeda G protein-coupled receptor 5 and NOD-like receptor family, pyrin domain containing 3—dependent manner in vivo. Reinforcing our conclusions from the mouse study, clinical SAP patients exhibited decreased serum content of conjugated BAs, especially GCDCA, which was inversely correlated with the severity of systemic inflammatory responses.ConclusionConjugated bile acids significantly inhibit NLRP3 inflammasome activation by activating TGR5 pathway, thereby alleviating pancreatic immunopathology. The results provide new insights into the variability of clinical outcomes and paves the way for developing more effective therapeutic interventions for AP.

Navigating from cellular phenotypic screen to clinical candidate: selective targeting of the NLRP3 inflammasome

The NLRP3 inflammasome plays a pivotal role in host defense and drives inflammation against microbial threats, crystals, and danger-associated molecular patterns (DAMPs). Dysregulation of NLRP3 activity is associated with various human diseases, making it an attractive therapeutic target. Patients with NLRP3 mutations suffer from Cryopyrin-Associated Periodic Syndrome (CAPS) emphasizing the clinical significance of modulating NLRP3. In this study, we present the identification of a novel chemical class exhibiting selective and potent inhibition of the NLRP3 inflammasome. Through a comprehensive structure–activity relationship (SAR) campaign, we optimized the lead molecule, compound A, for in vivo applications. Extensive in vitro and in vivo characterization of compound A confirmed the high selectivity and potency positioning compound A as a promising clinical candidate for diseases associated with aberrant NLRP3 activity. This research contributes to the ongoing efforts in developing targeted therapies for conditions involving NLRP3-mediated inflammation, opening avenues for further preclinical and clinical investigations.

Exploring Liraglutide in Lithium-Pilocarpine-Induced Temporal Lobe Epilepsy Model in Rats: Impact on Inflammation, Mitochondrial Function, and Behavior.

Background/Objectives: Glucagon-like peptide-1 receptor agonists such as liraglutide are known for their neuroprotective effects in neurodegenerative disorders, but their role in temporal lobe epilepsy (TLE) remains unclear. We aimed to investigate the effects of liraglutide on several biological processes, including inflammation, antioxidant defense mechanisms, mitochondrial dynamics, and function, as well as cognitive and behavioral changes in the TLE model. Methods: Low-dose, repeated intraperitoneal injections of lithium chloride-pilocarpine hydrochloride were used to induce status epilepticus (SE) in order to develop TLE in rats. Fifty-six male Sprague Dawley rats were subjected and allocated to the groups. The effects of liraglutide on inflammatory markers (NLRP3, Caspase-1, and IL-1β), antioxidant pathways (Nrf-2 and p-Nrf-2), and mitochondrial dynamics proteins (Pink1, Mfn2, and Drp1) were evaluated in hippocampal tissues via a Western blot. Mitochondrial function in peripheral blood mononuclear cells (PBMCs) was examined using flow cytometry. Cognitive-behavioral outcomes were assessed using the open-field, elevated plus maze, and Morris water maze tests. Results: Our results showed that liraglutide modulates NLRP3-mediated inflammation, reduces oxidative stress, and triggers antioxidative pathways through Nrf2 in SE-induced rats. Moreover, liraglutide treatment restored Pink1, Mfn2, and Drp1 levels in SE-induced rats. Liraglutide treatment also altered the mitochondrial function of PBMCs in both healthy and epileptic rats. This suggests that treatment can modulate mitochondrial dynamics and functions in the brain and periphery. Furthermore, in the behavioral aspect, liraglutide reversed the movement-enhancing effect of epilepsy. Conclusions: This research underscores the potential of GLP-1RAs as a possibly promising therapeutic strategy for TLE.

Galangin Alleviates Alcohol-Provoked Liver Injury Associated with Gut Microbiota Disorder and Intestinal Barrier Dysfunction in Mice.

Prolonged and excessive intake of alcohol results in the onset of alcoholic liver disease, which is marked by oxidative stress, intestinal barrier dysfunction, and disturbance in the intestinal microbiome. Galangin, a potent flavonoid from Alpinia officinarum Hance, has been recognized for its diverse biological properties; however, its ability for protecting against alcohol-stimulated hepatotoxicity remains unexplored in prior research. In the current study, a Gao-Binge mouse model was established to assess the positive role and mechanisms of galangin upon alcohol-induced liver injury. The administration of galangin relieved liver pathological damage, oxidative stress, and NLRP3-mediated inflammation induced by alcohol. In addition, galangin significantly reversed abnormal intestinal histopathological manifestations and damaged the intestinal barrier function. Furthermore, microbiota composition revealed that galangin improved intestinal imbalance by improving the gut microbiota dysbiosis and short-chain fatty acid level. Collectively, this study explored the interactions between phytochemical factors and virulence factors and discovered that galangin powerfully improved alcohol-induced liver disease by repressing the inflammatory cascade via the gut microbiota-mediated gut-liver axis. These results suggested that alcohol-targeted natural products could have potential applications in promoting food safety and human health and offer valuable insights into the possible use of these substances in these important areas.

Tyrobp deficiency blocks NLRP3-mediated inflammation and pyroptosis to alleviate myocardial ischemia-reperfusion injury through regulating Syk

PurposeThe present study aims to investigate the biological function of Tyrobp in myocardial ischemia-reperfusion injury (MIRI) and to clarify its potential reaction mechanisms. MethodsAC16 cells were induced by oxygen-glucose deprivation/reoxygenation (OGD/R) to simulate the MIRI in vitro. The cell transfection technology was used to downregulate Tyrobp, followed by assessment of cell damage, apoptosis and cytokines production via Cell Counting Kit (CCK)-8 assay, lactate dehydrogenase (LDH) release assay, TUNEL and ELISA assays, respectively. Immunofluorescence assay was performed to assess GSDMD. Corresponding proteins were detected via western blotting, and Co-immunoprecipitation (Co-IP) assay was used to validate proteins interaction. ResultsTyrobp was upregulated in OGD/R-exposed AC16 cells, and Tyrobp deficiency significantly alleviated OGD/R-caused cell viability loss, LDH release and cell apoptosis in AC16 cells. Meanwhile, Tyrobp deficiency inhibited the activation of NLRP3 inflammasome, reduced the production of cytokines and inhibited GSDMD intensity and GSDMD-N expression. Additionally, Tyrobp could interact with Syk and regulate Syk/NF-κB signaling. The rescue experiments showed that the above effects of Tyrobp deficiency on OGD/R-exposed AC16 cells were partly weakened by Syk overexpression. ConclusionTyrobp deficiency alleviated MIRI by inhibiting NLRP3-mediated inflammation and pyroptosis through regulating Syk, providing a novel target for the treatment of MIRI.

Dihydromyricetin suppresses endothelial NLRP3 inflammasome activation and attenuates atherogenesis by promoting mitophagy

BackgroundNOD-like receptor protein 3 (NLRP3) inflammasome activation is indispensable for atherogenesis. Mitophagy has emerged as a potential strategy to counteract NLRP3 inflammasome activation triggered by impaired mitochondria. Our previous research has indicated that dihydromyricetin, a natural flavonoid, can mitigate NLRP3-mediated endothelial inflammation, suggesting its potential to treat atherosclerosis. However, the precise underlying mechanisms remain elusive. This study sought to investigate whether dihydromyricetin modulates endothelial mitophagy and inhibits NLRP3 inflammasome activation to alleviate atherogenesis, along with the specific mechanisms involved.MethodsApolipoprotein E-deficient mice on a high-fat diet were administered daily oral gavages of dihydromyricetin for 14 weeks. Blood samples were procured to determine the serum lipid profiles and quantify proinflammatory cytokine concentrations. Aortas were harvested to evaluate atherosclerotic plaque formation and NLRP3 inflammasome activation. Concurrently, in human umbilical vein endothelial cells, Western blotting, flow cytometry, and quantitative real-time PCR were employed to elucidate the mechanistic role of mitophagy in the modulation of NLRP3 inflammasome activation by dihydromyricetin.ResultsDihydromyricetin administration significantly attenuated NLRP3 inflammasome activation and vascular inflammation in mice on a high-fat diet, thereby exerting a pronounced inhibitory effect on atherogenesis. Both in vivo and in vitro, dihydromyricetin treatment markedly enhanced mitophagy. This enhancement in mitophagy ameliorated the mitochondrial damage instigated by saturated fatty acids, thereby inhibiting the activation and nuclear translocation of NF-κB. Consequently, concomitant reductions in the transcript levels of NLRP3 and interleukin-1β (IL-1β), alongside decreased activation of NLRP3 inflammasome and IL-1β secretion, were discerned. Notably, the inhibitory effects of dihydromyricetin on the activation of NF-κB and subsequently the NLRP3 inflammasome were determined to be, at least in part, contingent upon its capacity to promote mitophagy.ConclusionThis study suggested that dihydromyricetin may function as a modulator to promote mitophagy, which in turn mitigates NF-κB activity and subsequent NLRP3 inflammasome activation, thereby conferring protection against atherosclerosis.

Apelin-13-Loaded Macrophage Membrane-Encapsulated Nanoparticles for Targeted Ischemic Stroke Therapy via Inhibiting NLRP3 Inflammasome-Mediated Pyroptosis.

Ischemic stroke is a refractory disease wherein the reperfusion injury caused by sudden restoration of blood supply is the main cause of increased mortality and disability. However, current therapeutic strategies for the inflammatory response induced by cerebral ischemia-reperfusion (I/R) injury are unsatisfactory. This study aimed to develop a functional nanoparticle (MM/ANPs) comprising apelin-13 (APNs) encapsulated in macrophage membranes (MM) modified with distearoyl phosphatidylethanolamine-polyethylene glycol-RVG29 (DSPE-PEG-RVG29) to achieve targeted therapy against ischemic stroke. MM were extracted from RAW264.7. PLGA was dissolved in dichloromethane, while Apelin-13 was dissolved in water, and CY5.5 was dissolved in dichloromethane. The precipitate was washed twice with ultrapure water and then resuspended in 10 mL to obtain an aqueous solution of PLGA nanoparticles. Subsequently, the cell membrane was evenly dispersed homogeneously and mixed with PLGA-COOH at a mass ratio of 1:1 for the hybrid ultrasound. DSPE-PEG-RVG29 was added and incubated for 1 h to obtain MM/ANPs. In this study, we developed a functional nanoparticle delivery system (MM/ANPs) that utilizes macrophage membranes coated with DSPE-PEG-RVG29 peptide to efficiently deliver Apelin-13 to inflammatory areas using ischemic stroke therapy.MM/ANPs effectively cross the blood-brain barrier and selectively accumulate in ischemic and inflamed areas. In a mouse I/R injury model, these nanoparticles significantly improved neurological scores and reduced infarct volume.Apelin-13 is gradually released from the MM/ANPs, inhibiting NLRP3 inflammasome assembly by enhancing sirtuin 3 (SIRT3) activity, which suppresses the inflammatory response and pyroptosis. The positive regulation of SIRT3 further inhibits the NLRP3-mediated inflammation, showing the clinical potential of these nanoparticles for ischemic stroke treatment. The biocompatibility and safety of MM/ANPs were confirmed through in vitro cytotoxicity tests, blood-brain barrier permeability tests, biosafety evaluations, and blood compatibility studies. MM/ANPs offer a highly promising approach to achieve ischemic stroke-targeted therapy inhibiting NLRP3 inflammasome-mediated pyroptosis.

Coenzyme Q10 ameliorates lipopolysaccharide-induced acute lung injury by attenuating oxidative stress and NLRP3 inflammation through regulating mitochondrial dynamics

Increasing evidence has demonstrated that coenzyme Q10 (CoQ10) exhibits a range of biological properties. Herein, we explored the protective effect and potential molecular mechanism of CoQ10 on lipopolysaccharide (LPS)-induced acute lung injury (ALI). We found that medium (10 mg/kg) and high (50 mg/kg) doses of CoQ10 ameliorated LPS (50 µg/µL)-induced ALI to varying degrees, as demonstrated by reduced lung coefficient, lower wet/dry weight lung tissue ratio, decreased bronchoalveolar lavage fluid protein concentration, less anatomical and histopathological damage to the lung, and increased expression of proteins related to lung epithelial barrier structure. CoQ10 also alleviated LPS-induced oxidative stress and inflammation mediated by NOD-like receptor protein 3 (NLRP3) by reducing the reactive oxygen species (ROS), malondialdehyde, and mitochondrial ROS concentrations, increasing superoxide dismutase, glutathione, and catalase activity, and decreasing NLRP3 expression at the protein and mRNA levels. Moreover, CoQ10 alleviated structural and functional damage to the mitochondria, inhibited mitochondrial fission, and promoted mitochondrial fusion, mainly by inhibiting phosphorylation of dynamin-related protein 1 (Drp1) at Ser616 and Ser637. Correlation analysis revealed that mitochondrial fission (especially Drp1) was positively correlated with oxidative stress, NLRP3-mediated inflammation, and structural damage to the lung epithelial barrier. Molecular docking analysis showed that CoQ10 binds stably to Drp1, with a binding energy of −5.9 kcal/mol. Furthermore, the use of schaftoside (a Drp1 inhibitor) has further elucidated the mechanism of action of CoQ10. Together, these results suggest that CoQ10 alleviates LPS-induced ALI by regulating mitochondrial dynamics, attenuating oxidative stress, and decreasing NLRP3-medated inflammation, thereby promoting lung epithelial barrier structural remodeling.

The Protective Effects of Ruscogenin Against Lipopolysaccharide-Induced Myocardial Injury in Septic Mice.

Sepsis-induced myocardial dysfunction commonly occurs in individuals with sepsis and is a severe complication with high morbidity and mortality rates. This study aimed to investigate the effects and potential mechanisms of the natural steroidal sapogenin ruscogenin (RUS) against lipopolysaccharide (LPS)-induced myocardial injury in septic mice. We found that RUS effectively alleviated myocardial pathological damage, normalized cardiac function, and increased survival in septic mice. RNA sequencing demonstrated that RUS administration significantly inhibited the activation of the NOD-like receptor signaling pathway in the myocardial tissues of septic mice. Subsequent experiments further confirmed that RUS suppressed myocardial inflammation and pyroptosis during sepsis. In addition, cultured HL-1 cardiomyocytes were challenged with LPS, and we observed that RUS could protect these cells against LPS-induced cytotoxicity by suppressing inflammation and pyroptosis. Notably, both the in vivo and in vitro findings indicated that RUS inhibited NOD-like receptor protein-3 (NLRP3) upregulation in cardiomyocytes stimulated with LPS. As expected, knockdown of NLRP3 blocked the LPS-induced activation of inflammation and pyroptosis in HL-1 cells. Furthermore, the cardioprotective effects of RUS on HL-1 cells under LPS stimulation were abolished by the novel NLRP3 agonist BMS-986299. Taken together, our results suggest that RUS can alleviate myocardial injury during sepsis, at least in part by suppressing NLRP3-mediated inflammation and pyroptosis, highlighting the potential of this molecule as a promising candidate for sepsis-induced myocardial dysfunction therapy.

Raddeanin A Protects the BRB Through Inhibiting Inflammation and Apoptosis in the Retina of Alzheimer's Disease.

Neuroinflammation and endothelial cell apoptosis are prominent features of blood-brain barrier (BBB) disruption, which have been described in Alzheimer's disease (AD) and can predict cognitive decline. Recent reports revealed vascular β-amyloid (Aβ) deposits, Muller cell degeneration and microglial dysfunction in the retina of AD patients. However, there has been no in-depth research on the roles of inflammation, retinal endothelial cell apoptosis, and blood-retinal barrier (BRB) damage in AD retinopathy. We found that Raddeanin A (RDA) could improve pathological and cognitive deficits in a mouse model of Alzheimer's disease by targeting β-amyloidosis, However, the effects of RDA on AD retinal function require further study. To clarify whether RDA inhibits inflammation and apoptosis and thus improves BRB function in AD-related retinopathy. In vitro we used Aβ-treated HRECs and MIO-M1 cells, and in vivo we used 3×Tg-AD mice to investigate the effect of RDA on BRB in AD-related retinopathy. We found that RDA could improve BRB function in AD-related retinopathy by inhibiting NLRP3-mediated inflammation and suppressing Wnt/β-catenin pathway-mediated apoptosis, which is expected to improve the pathological changes in AD-related retinopathy and the quality of life of AD patients.

Paeoniflorin alleviates depression by inhibiting the activation of NLRP3 inflammasome via promoting mitochondrial autophagy

Depression ranks among the most common neuropsychiatric disorders globally. Current studies examining the roles of inflammation and mitochondrial autophagy in the antidepressant efficacy of paeoniflorin (PF) are sparse. This study aimed to elucidate PF’s antidepressant mechanism by promoting autophagy and inhibiting NLRP3 inflammasome activation using chronic unpredictable mild stimulation (CUMS)-induced C57BL/6 mouse models in vivo and corticosterone (CORT)-induced HT22 cell models in vitro. Results demonstrated that PF enhanced the viability of HT22 cells following CORT exposure, restored mitochondrial membrane potential (MMP), reduced reactive oxygen species accumulation, increased LC3 fluorescence intensity, and suppressed inflammatory cytokine secretion and inflammation activation. Additionally, PF ameliorated depressive behaviors induced by CUMS and improved damage in hippocampal neurons. It also reduced the expression of NLRP3, ASC, Caspase-1, IL-1β, and the assembly of the NLRP3 inflammasome. Moreover, PF upregulated the expression of autophagy-related proteins in the hippocampus, facilitating the clearance of damaged mitochondria and enhancing autophagy. The role of autophagy in PF’s antidepressant effects was further confirmed through the use of the autophagy inhibitor 3-methyladenine (3-MA), which reduced the efficacy of PF. In conclusion, PF effectively improved depressive behaviors in CUMS-induced mice and reduced NLRP3-mediated inflammation both in vivo and in vitro, likely via the induction of autophagy.

Female Type 1 Diabetic Akita Mice Demonstrate Increased Bladder Contractility via FP Receptor Activation due to NLRP3-Mediated Inflammation.

Diabetic bladder dysfunction (DBD) is driven in part by inflammation which dysregulates prostaglandin release in the bladder. Precise inflammatory mechanisms responsible for such dysregulation have been elusive. Since prostaglandins impact bladder contractility, elucidating these mechanisms may yield potential therapeutic targets for DBD. In female Type 1 diabetic Akita mice, inflammation mediated by the nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome is responsible for DBD. Here, we utilized female Akita mice crossbred with NLRP3 knock-out mice to determine how NLRP3-driven inflammation impacts prostaglandin release within the bladder and prostaglandin-mediated bladder contractions. Akita mice were crossbred with NLRP3-⁣/- mice to yield four groups of non-diabetics and diabetics with and without the NLRP3 gene. Females were aged to 30 weeks when Akitas typically exhibit DBD. Urothelia and detrusors were stretched ex vivo to release prostaglandins. Prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2α) were quantified using enzyme linked immunosorbent assays (ELISA). In separate samples, ex vivo contractile force to PGE2 and PGF2α +/- the prostaglandin F (FP) receptor antagonist, AL8810, was measured. FP receptor protein expression was determined via western blotting. Stretch-induced PGE2 release increases in urothelia but decreases in detrusors of diabetics. However, PGE2-mediated bladder contractions are not impacted. Conversely, diabetics show no changes in PGF2α release, but PGF2α-mediated contractions increase significantly. This is likely due to signaling through the FP receptors as FP receptor antagonism prevents this increase and diabetics demonstrate a four-fold increase in FP receptor proteins. Without NLRP3-mediated inflammation, changes in prostaglandin release, contractility, and receptor expression do not occur. NLRP3-dependent inflammation dysregulates prostaglandin release and prostaglandin-mediated bladder contractions in diabetic female Akita mice via FP receptor upregulation.

GSNOR negatively regulates the NLRP3 inflammasome via S-nitrosation of MAPK14.

Hyperactivation of the NLRP3 inflammasome has been implicated in the pathogenesis of numerous diseases. However, the precise molecular mechanisms that modulate the transcriptional regulation of NLRP3 remain largely unknown. In this study, we demonstrated that S-nitrosoglutathione reductase (GSNOR) deficiency in macrophages leads to significant increases in the Nlrp3 and Il-1β expression levels and interleukin-1β (IL-1β) secretion in response to NLRP3 inflammasome stimulation. Furthermore, in vivo experiments utilizing Gsnor-/- mice revealed increased disease severity in both lipopolysaccharide (LPS)-induced septic shock and dextran sodium sulfate (DSS)-induced colitis models. Additionally, we showed that both LPS-induced septic shock and DSS-induced colitis were ameliorated in Gsnor-/- Nlrp3-/- double-knockout (DKO) mice. Mechanistically, GSNOR deficiency increases the S-nitrosation of mitogen-activated protein kinase 14 (MAPK14) at the Cys211 residue and augments MAPK14 kinase activity, thereby promoting Nlrp3 and Il-1β transcription and stimulating NLRP3 inflammasome activity. Our findings suggested that GSNOR is a regulator of the NLRP3 inflammasome and that reducing the level of S-nitrosylated MAPK14 may constitute an effective strategy for alleviating diseases associated with NLRP3-mediated inflammation.

METTL3-deficiency m6A-dependently degrades MALAT1 to suppress NLRP3-mediated pyroptotic cell death and inflammation in Mycobacterium tuberculosis (H37Ra strain)-infected mouse macrophages

Mycobacterium tuberculosis (Mtb)-infected macrophages aggravated the development of pulmonary tuberculosis, but its detailed molecular mechanisms are still largely unknown. Here, the mouse primary peritoneal macrophages were infected with the attenuated strain of Mtb H37Ra, and we firstly verified that targeting a novel METTL3/N6-Methyladenosine (m6A)/LncRNA MALAT1/miR-125b/TLR4 axis was effective to suppress pyroptotic cell death in the Mtb-infected macrophages. Specifically, through performing Real-Time qPCR and Western Blot analysis, we validated that METTL3, LncRNA MALAT1 and TLR4 were elevated, whereas miR-125b and the anti-oxidant agents (Nrf2 and HO-1) were downregulated in Mtb-infected mouse macrophages. In addition, functional experiments confirmed that both ROS scavenger NAC and METTL3-ablation downregulated NLRP3, GSDMD-C, cleaved Caspase-1 and ASC to restrain pyroptotic cell death and decreased the expression levels of IL-1β, IL-18, IL-6 and TNF-α to restrain inflammatory cytokines expression in Mtb-infected macrophages. Next, METTL3-ablation induced m6A-demethylation and instability in LncRNA MALAT1, and low-expressed LncRNA MALAT1 caused TLR4 downregulation through sponging miR-125b, resulting in the inactivation of NLRP3 inflammasome. Finally, silencing of METTL3-induced protective effects in Mtb-infected macrophages were all abrogated by overexpressing LncRNA MALAT1 and downregulating miR-125b. Thus, we concluded that targeting METTL3-mediated m6A modifications suppressed Mtb-induced pyroptotic cell death in mouse macrophages, and the downstream LncRNA MALAT1/miR-125b/TLR4 axis played critical role in this process.

BCL6 attenuates hyperoxia-induced lung injury by inhibiting NLRP3-mediated inflammation in fetal mouse

Background The transcriptional repressor B-cell lymphoma 6 (BCL6) has been reported to inhibit inflammation. So far, experimental evidence for the role of BCL6 in bronchopulmonary dysplasia (BPD) is lacking. Our study investigated the roles of BCL6 in the progression of BPD and its downstream mechanisms. Methods Hyperoxia or lipopolysaccharide (LPS) was used to mimic the BPD mouse model. To investigate the effects of BCL6 on BPD, recombination adeno-associated virus serotype 9 expressing BCL6 (rAAV9-BCL6) and BCL6 inhibitor FX1 were administered in mice. The pulmonary pathological changes, inflammatory chemokines and NLRP3-related protein were observed. Meanwhile, BCL6 overexpression plasmid was used in human pulmonary microvascular endothelial cells (HPMECs). Cell proliferation, apoptosis, and NLRP3-related protein were detected. Results Either hyperoxia or LPS suppressed pulmonary BCL6 mRNA expression. rAAV9-BCL6 administration significantly inhibited hyperoxia-induced NLRP3 upregulation and inflammation, attenuated alveolar simplification and dysregulated angiogenesis in BPD mice, which were characterized by decreased mean linear intercept, increased radical alveolar count and alveoli numbers, and the upregulated CD31 expression. Meanwhile, BCL6 overexpression promoted proliferation and angiogenesis, inhibited apoptosis and inflammation in hyperoxia-stimulated HPMECs. Moreover, administration of BCL6 inhibitor FX1 arrested growth and development. FX1-treated BPD mice exhibited exacerbation of alveolar pathological changes and pulmonary vessel permeability, with upregulated mRNA levels of pro-inflammatory cytokines and pro-fibrogenic factors. Furthermore, both rAAV9-BCL6 and FX1 administration exerted a long-lasting effect on hyperoxia-induced lung injury (≥4 wk). Conclusions BCL6 inhibits NLRP3-mediated inflammation, attenuates alveolar simplification and dysregulated pulmonary vessel development in hyperoxia-induced BPD mice. Hence, BCL6 may be a target in treating BPD and neonatal diseases.

FOSL1 regulates hyperproliferation and NLRP3-mediated inflammation of psoriatic keratinocytes through the NF-kB signaling via transcriptionally activating TRAF3

Psoriasis is a common and immune-mediated skin disease related to keratinocytes hyperproliferation and inflammation. Fos-like antigen-1 (FOSL1) is an important transcription factor involved in various diseases. FOSL1 has been reported to be differentially expressed in psoriasis. However, the roles and mechanism of FOSL1 in psoriasis progression remain largely unknown. FOSL1 is an upregulated transcription factor in psoriasis and increased in M5-treated HaCaT cells. FOSL1 had a diagnostic value in psoriasis, and positively associated with PASI score, TNF-α and IL-6 levels in psoriasis patients. FOSL1 silencing attenuated M5-induced HaCaT cell hyperproliferation through decreasing cell viability and proliferative ability and increasing cell apoptosis. FOSL1 knockdown mitigated M5-induced NLRP3 inflammasome activation and it-mediated inflammatory cytokine (IL-6, IL-8 and CCL17) expression. TRAF3 expression was increased in psoriasis patients and M5-treated HaCaT cells. FOSL1 transcriptionally activating TRAF3 in HaCaT cells. TRAF3 overexpression reversed the suppressive effects of FOSL1 silencing on M5-induced hyperproliferation and NLRP3-mediated inflammation. FOSL1 knockdown attenuated M5-induced NF-κB signaling activation by reducing TRAF3. Activation of NF-κB signaling reversed the effects of FOSL1 knockdown on hyperproliferation and inflammation in M5-treated cells. FOSL1 silencing prevented M5-induced hyperproliferation and NLRP3-mediated inflammation of keratinocytes by inhibiting TRAF3-mediated NF-κB activity, indicating FOSL1 might act as a therapeutic target of psoriasis.