Inhibition of the NLRP3 inflammasome attenuates spiral ganglion neuron degeneration in aminoglycoside-induced hearing loss

Aminoglycosides are a widely used class of antibacterials renowned for their effectiveness and broad antimicrobial spectrum.However,their use leads to irreversible hearing damage by causing apoptosis of hair cells as their direct target.In addition,the hearing damage caused by aminoglycosides involves damage of spiral ganglion neurons upon exposure.To investigate the mechanisms underlying spiral ganglion neuron degeneration induced by aminoglycosides,we used a C57BL/6J mouse model treated with kanamycin.We found that the mice exhibited auditory deficits following the acute loss of outer hair cells.Spiral ganglion neurons displayed hallmarks of pyroptosis and exhibited progressive degeneration over time.Transcriptomic profiling of these neurons showed significant upregulation of genes associated with inflammation and immune response,particularly those related to the NLRP3 inflammasome.Activation of the canonical pyroptotic pathway in spiral ganglion neurons was observed,accompanied by infiltration of macrophages and the release of proinflammatory cytokines.Pharmacological intervention targeting NLRP3 using Mcc950 and genetic intervention using NLRP3 knockout ameliorated spiral ganglion neuron degeneration in the injury model.These findings suggest that NLRP3 inflammasome-mediated pyroptosis plays a role in aminoglycoside-induced spiral ganglion neuron degeneration.Inhibition of this pathway may offer a potential therapeutic strategy for treating sensorineural hearing loss by reducing spiral ganglion neuron degeneration.

Overexpression of low-density lipoprotein receptor prevents neurotoxic polarization of astrocytes via inhibiting NLRP3 inflammasome activation in experimental ischemic stroke

Neurotoxic astrocytes are a promising therapeutic target for the attenuation of cerebral ischemia/reperfusion injury.Low-density lipoprotein receptor,a classic cholesterol regulatory receptor,has been found to inhibit NLR family pyrin domain containing protein 3(NLRP3)inflammasome activation in neurons following ischemic stroke and to suppress the activation of microglia and astrocytes in individuals with Alzheimer’s disease.However,little is known about the effects of low-density lipoprotein receptor on astrocytic activation in ischemic stroke.To address this issue in the present study,we examined the mechanisms by which low-density lipoprotein receptor regulates astrocytic polarization in ischemic stroke models.First,we examined low-density lipoprotein receptor expression in astrocytes via immunofluorescence staining and western blotting analysis.We observed significant downregulation of low-density lipoprotein receptor following middle cerebral artery occlusion reperfusion and oxygen-glucose deprivation/reoxygenation.Second,we induced the astrocyte-specific overexpression of low-density lipoprotein receptor using astrocyte-specific adeno-associated virus.Low-density lipoprotein receptor overexpression in astrocytes improved neurological outcomes in middle cerebral artery occlusion mice and reversed neurotoxic astrocytes to create a neuroprotective phenotype.Finally,we found that the overexpression of low-density lipoprotein receptor inhibited NLRP3 inflammasome activation in oxygen-glucose deprivation/reoxygenation injured astrocytes and that the addition of nigericin,an NLRP3 agonist,restored the neurotoxic astrocyte phenotype.These findings suggest that low-density lipoprotein receptor could inhibit the NLRP3-meidiated neurotoxic polarization of astrocytes and that increasing low-density lipoprotein receptor in astrocytes might represent a novel strategy for treating cerebral ischemic stroke.

Microglial NLRP3 inflammasome-mediated neuroinflammation and therapeutic strategies in depression

Previous studies have demonstrated a bidirectional relationship between inflammation and depression.Activation of the nucleotide-binding oligomerization domain,leucine-rich repeat,and NLR family pyrin domain-containing 3(NLRP3)inflammasomes is closely related to the pathogenesis of various neurological diseases.In patients with major depressive disorder,NLRP3 inflammasome levels are significantly elevated.Understanding the role that NLRP3 inflammasome-mediated neuroinflammation plays in the pathogenesis of depression may be beneficial for future therapeutic strategies.In this review,we aimed to elucidate the mechanisms that lead to the activation of the NLRP3 inflammasome in depression as well as to provide insight into therapeutic strategies that target the NLRP3 inflammasome.Moreover,we outlined various therapeutic strategies that target the NLRP3 inflammasome,including NLRP3 inflammatory pathway inhibitors,natural compounds,and other therapeutic compounds that have been shown to be effective in treating depression.Additionally,we summarized the application of NLRP3 inflammasome inhibitors in clinical trials related to depression.Currently,there is a scarcity of clinical trials dedicated to investigating the applications of NLRP3 inflammasome inhibitors in depression treatment.The modulation of NLRP3 inflammasomes in microglia holds promise for the management of depression.Further investigations are necessary to ascertain the efficacy and safety of these therapeutic approaches as potential novel antidepressant treatments.

Elaidic acid-induced intestinal barrier damage led to gut-liver axis derangement and triggered NLRP3 inflammasome in the liver of SD rats

Previous studies have shown that trans fatty acids(TFA) are associated with several chronic diseases,the gut microbiota is directly influenced by dietary components and linked to chronic diseases.Our research investigated the effects of elaidic acid(EA),a typical TFA,on the gut microbiota to understand the underlying mechanisms of TFA-related chronic diseases.16S rDNA gene sequencing on faecal samples from Sprague-Dawley rats were performed to explore the composition change of the gut microbiota by EA gavage for 4 weeks.The results showed that the intake of EA increased the abundance of well-documented harmful bacteria,such as Proteobacteria,Anaerotruncus,Oscillibacter and Desulfovibrionaceae.Plus,EA induced translocation of lipopolysaccharides(LPS) and the above pathogenic bacteria,disrupted the intestinal barrier,led to gut-liver axis derangement and TLR4 pathway activation in the liver.Overall,EA induced intestinal barrier damage and regulated TLR4-MyD88-NF-κB/MAPK pathways in the liver of SD rats,leading to the activation of NLRP3 inflammasome and inflammatory liver damage.

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 16.9µg/L CCEO for 1 h followed by 10µmol/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-1β,as well as reduced protein levels of NLRP3,ASC,pro-caspase-1,caspase-1(p20),GSDMD-FL,GSDMD-N,and pro-IL-1β.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.

Attenuation of the Activation of NLRP3 Inflammasome in Fibroblast Like Synoviocytes of Rheumatoid Arthritis by Baicalin through Regulating the Let-7i-3p/PI3K/Akt/NF-κB Signaling Axis

[Objectives]To study the effect and mechanism of baicalin on the activation of NLRP3 inflammasome in human fibroblast like synoviocytes of rheumatoid arthritis(HFLS-RA).[Methods]To confirm that baicalin alleviated the activation of NLRP3 inflammasome in HFLS-RA,the expression of NLRP3 before and after baicalin treatment was observed by immunofluorescence.Western blot was used to detect the protein expression of p-PI3K,p-Akt,NF-κB p65,NLRP3,ASC and caspase-1 after baicalin treatment for 48 h,and the contents of IL-1 and IL-18 in the supernatents were detected by ELISA.In order to explore the mechanism of baicalin alleviating the activation of NLRP3 inflammasome,the corresponding relationship between let-7i-3p and PIK3CA was verified by double luciferin and Westen blot analysis.The expression of let-7i-3p and PI3K before and after baicalin intervention was detected by RT-qPCR.let-7i-3p interference was used to verify whether baicalin mitigated the activation of enhanced NLRP3 inflammasome.[Results]Baicalin(50 and 100 mg/L)significantly reduced the activation of NLRP3 inflammasome,inhibited the protein expressions of p-PI3K,p-Akt,NF-κB p65,NLRP3,ASC and caspase-1,and the secretion of IL-1 and IL-18.let-7i-3p and PIK3CA had a targeted correspondence,and baicalin up-regulated the expression of let-7i-3p and down-regulated the expression of PIK3CA.Baicalin attenuated the activation of NLRP3 inflammasome enhanced by let-7i-3p interference.[Conclusions]Baicalin can up-regulate let-7i-3p expression,inhibit PI3K/Akt/NF-κB signal transduction,and thus reduce the activation of NLRP3 inflammasome in HFLS-RA.

3'-Deoxyadenosin alleviates methamphetamine-induced aberrant synaptic plasticity and seeking behavior by inhibiting the NLRP3 inflammasome

Methamphetamine addiction is a brain disorder characterized by persistent drug-seeking behavior, which has been linked with aberrant synaptic plasticity. An increasing body of evidence suggests that aberrant synaptic plasticity is associated with the activation of the NOD-like receptor family pyrin domain containing-3(NLRP3) inflammasome. 3′-Deoxyadenosin, an active component of the Chinese fungus Cordyceps militaris, has strong anti-inflammatory effects. However, whether 3′-deoxyadenosin attenuates methamphetamine-induced aberrant synaptic plasticity via an NLRP3-mediated inflammatory mechanism remains unclear. We first observed that 3′-deoxyadenosin attenuated conditioned place preference scores in methamphetamine-treated mice and decreased the expression of c-fos in hippocampal neurons. Furthermore, we found that 3′-deoxyadenosin reduced the aberrant potentiation of glutamatergic transmission and restored the methamphetamine-induced impairment of synaptic plasticity. We also found that 3′-deoxyadenosin decreased the expression of NLRP3 and neuronal injury. Importantly, a direct NLRP3 deficiency reduced methamphetamine-induced seeking behavior, attenuated the impaired synaptic plasticity, and prevented neuronal damage. Finally, NLRP3 activation reversed the effect of 3′-deoxyadenosin on behavior and synaptic plasticity, suggesting that the anti-neuroinflammatory mechanism of 3′-deoxyadenosin on aberrant synaptic plasticity reduces methamphetamine-induced seeking behavior. Taken together, 3′-deoxyadenosin alleviates methamphetamine-induced aberrant synaptic plasticity and seeking behavior by inhibiting the NLRP3 inflammasome.

The Alzheimer's disease-associated gene TREML2 modulates inflammation by regulating microglia polarization and NLRP3 inflammasome activation

Triggering receptor expressed on myeloid cells-like 2(TREML2)is a newly identified susceptibility gene for Alzheimer's disease(AD).It encodes a microglial inflammation-associated receptor.To date,the potential role of mic roglial TREML2 in neuroinflammation in the context of AD remains unclear.In this study,APP/PS1 mice were used to investigate the dynamic changes of TREML2 levels in brain during AD progression.In addition,lipopolysaccharide(LPS)stimulation of primary microglia as well as a lentivirus-mediated TREML2 overexpression and knockdown were employed to explore the role of TREML2 in neuroinflammation in the context of AD.Our res ults show that TREML2 levels gradually increased in the brains of AP P/PS1 mice during disease progression.LPS stimulation of primary microglia led to the release of inflammato ry cytokines including interleukin-1β,inte rleukin-6,and tumor necrosis factor-a in the culture medium.The LPS-induced mic roglial release of inflammatory cytokines was enhanced by TREML2 overexpression and was attenuated by TREML2 knoc kdown.LPS increased the levels of mic roglial M1-type polarization marker inducible nitric oxide synthase.This effect was enhanced by TREML2 overexpression and ameliorated by TREML2 knockdown.Furthermore,the levels of microglial M2-type polarization markers CD206 and ARG1 in the primary microglia were reduced by TREML2 overexpression and elevated by TREML2 knockdown.LPS stimulation increased the levels of NLRP3 in primary microglia.The LPS-induced increase in NLRP3 was further elevated by TREML2 overexpression and alleviated by TREML2 knockdown.In summary,this study provides the first evidence that TREML2 modulates inflammation by regulating microglial polarization and NLRP3 inflammasome activation.These findings reveal the mechanisms by which TREML2 regulates microglial inflammation and suggest that TREML2 inhibition may represent a novel therapeutic strategy for AD.

Hypoxic preconditioning reduces NLRP3 inflammasome expression and protects against cerebral ischemia/reperfusion injury

Hypoxic preconditioning can protect against cerebral ischemia/reperfusion injury. However, the underlying mechanisms that mediate this effect are not completely clear. In this study, mice were pretreated with continuous, intermittent hypoxic preconditioning;1 hour later, cerebral ischemia/reperfusion models were generated by middle cerebral artery occlusion and reperfusion. Compared with control mice, mice with cerebral ischemia/reperfusion injury showed increased Bederson neurological function scores, significantly increased cerebral infarction volume, obvious pathological damage to the hippocampus, significantly increased apoptosis;upregulated interleukin-1β, interleukin-6, and interleukin-8 levels in brain tissue;and increased expression levels of NOD-like receptor family pyrin domain containing 3(NLRP3), NLRP inflammasome-related protein caspase-1, and gasdermin D. However, hypoxic preconditioning significantly inhibited the above phenomena. Taken together, these data suggest that hypoxic preconditioning mitigates cerebral ischemia/reperfusion injury in mice by reducing NLRP3 inflammasome expression. This study was approved by the Medical Ethics Committee of the Fourth Hospital of Baotou, China(approval No. DWLL2019001) in November 2019.

Vav1 promotes inflammation and neuronal apoptosis in cerebral ischemia/reperfusion injury by upregulating microglial and NLRP3 inflammasome activation

Microglia,which are the resident macrophages of the central nervous system,are an important part of the inflammatory response that occurs after cerebral ischemia.Vav guanine nucleotide exchange factor 1(Vav1) is a guanine nucleotide exchange factor that is related to microglial activation.However,how Vav1 participates in the inflammato ry response after cerebral ischemia/reperfusion inj ury remains unclea r.In this study,we subjected rats to occlusion and repe rfusion of the middle cerebral artery and subjected the BV-2 mic roglia cell line to oxygen-glucose deprivatio n/reoxygenation to mimic cerebral ischemia/repe rfusion in vivo and in vitro,respectively.We found that Vav1 levels were increased in the brain tissue of rats subjected to occlusion and reperfusion of the middle cerebral arte ry and in BV-2 cells subjected to oxygen-glucose deprivation/reoxygenation.Silencing Vav1 reduced the cerebral infarct volume and brain water content,inhibited neuronal loss and apoptosis in the ischemic penumbra,and im p roved neurological function in rats subjected to occlusion and repe rfusion of the middle cerebral artery.Further analysis showed that Vav1 was almost exclusively localized to microglia and that Vav1 downregulation inhibited microglial activation and the NOD-like receptor pyrin 3(NLRP3) inflammasome in the ischemic penumbra,as well as the expression of inflammato ry facto rs.In addition,Vov1 knoc kdown decreased the inflammatory response exhibited by BV-2 cells after oxygen-glucose deprivation/reoxyge nation.Taken together,these findings show that silencing Vav1 attenuates inflammation and neuronal apoptosis in rats subjected to cerebral ischemia/repe rfusion through inhibiting the activation of mic roglia and NLRP3 inflammasome.

Lactobacillus rhamnosus GR-1 attenuates foodborne Bacillus cereus-induced NLRP3 inflammasome activity in bovine mammary epithelial cells by protecting intercellular tight junctions

Background:Bacillus cereus is an important pathogen that causes human food poisoning,specifically diarrhea and vomiting.B.cereus can also induce mastitis in dairy cows and has a strong survival ability in milk,as it cannot be inactivated by high-temperature short-time pasteurization.Therefore,B.cereus can enter the market through pasteurized milk and other dairy products,imposing enormous hidden dangers on food safety and human health.Results:In this study,B.cereus 2101(BC)was isolated from milk samples of cows with mastitis.BC grew rapidly with strong hemolysis,making it difficult to prevent mastitis and ensure food security.MAC-T cells were treated with BC and/or Lactobacillus rhamnosus GR-1(LGR-1).Pretreatment with LGR-1 protected the integrity of tight junctions and the expression of zonula occludens-1(ZO-1)and occludin destroyed by BC.Furthermore,LGR-1 pretreatment reduced the expression of NOD-like receptor family member pyrin domain-containing protein 3(NLRP3),caspase recruitment and activation domain(ASC),Caspase-1 p20,gasdermin D(GSDMD)p30,inflammatory factors(interleukin(IL)-1βand IL-18),and cell death induced by BC.Moreover,LGR-1 pretreatment reduced NLRP3 inflammasome activity and increased expressions of ZO-1 and occludin induced by lipopolysaccharides(LPS)+ATP stimulation.MAC-T cells were transfected with NLRP3 si RNA or MCC950 and/or treated with BC and/or LGR-1.NLRP3-si RNA transfection and MCC950 attenuated BC-induced NLRP3 inflammasome activity.Expression of inflammatory cytokines and cell death suggested that the inflammatory pathway might play an important role in the induction of the NLRP3 inflammasome by BC and the protection of LGR-1.Conclusions:These results suggest that LGR-1 might be a probiotic alternative to antibiotics and could be administered to prevent mastitis in dairy cows,thus ensuring food security.

Glycogen Synthase Kinase-3β,NLRP3 Inflammasome,and Alzheimer's Disease

Alzheimer’s disease (AD) is the most prevalent cause of dementia worldwide. Because of the progressive neurodegeneration, individual cognitive and behavioral functions are impaired, affecting the quality of life of millions of people. Although the exact pathogenesis of AD has not been fully elucidated, amyloid plaques, neurofibrillary tangles (NFTs), and sustaining neuroinflammation dominate its characteristics. As one of the major tau kinases leading to hyperphosphorylation and aggregation of tau, glycogen synthase kinase-3β (GSK-3β) has been drawing great attention in various AD studies. Another research focus of AD in recent years is the inflammasome, a multiprotein complex acting as a regulator in immunological reactions to exogenous and endogenous danger signals, of which the Nod-like receptor (NLR) family, pyrin domain-containing 3 (NLRP3) inflammasome has been studied mostly in AD and proven to play a significant role in AD development by its activation and downstream effects such as caspase-1 maturation and interleukin (IL)-1β release. Studies have shown that the NLRP3 inflammasome is activated in a GSK-3β-dependent way and that inhibition of the NLRP3 inflammasome downregulates GSK-3β, suggesting that these two important proteins are closely related. This article reviews the respective roles of GSK-3β and the NLRP3 inflammasome in AD as well as their relationship and interaction.

Linarin ameliorates innate inflammatory response in an experimental dry eye model via modulation of the NLRP3 inflammasome

Objective To investigate the effect and mechanism of linarin(LA) in an experimental dry eye model.Methods LA or vehicle was applied in two dry eye models: an in vitro hyperosmotic stress model and an in vivo desiccating stress(DS) murine model. The viability of human corneal epithelial cells(HCECs) was measured using a cell counting kit(CCK-8).Tear secretion was assessed using the phenol red cotton test. The tear break-up time(TBUT) was recorded using 0.1% liquid fluorescein sodium. Corneal epithelial permeability was evaluated through Oregon green dextran(OGD) staining.Conjunctival goblet cells were counted using periodic acid-Schiff(PAS) staining. Terminal deoxynucleotidyl transfer d UTP nickend labeling(TUNEL) staining was used to quantify apoptotic cells in both models. The expression of Ki-67 was measured in HCECs in the cell model while that of matrix metalloproteinase(MMP)-3 and-9 was measured in the murine model through immunofluorescence staining. Real-time quantitative PCR(RTqPCR) was performed to assess the expression of MMP-3 and MMP-9 in the corneal epithelium and NLRP3, ASC, Caspase-1,interleukin(IL)-1β, IL-18, and tumor necrosis factor(TNF)-α in the conjunctiva. The protein expression levels of NLRP3, ASC,Caspase-1, IL-1β, and IL-18 in the conjunctiva were assessed via Western blot.Results In the in vitro model, treatment of HCECs with LA showed no toxicity, increased proliferation, and reduced apoptosis. In the murine model, compared to the control, LA significantly increased tear production and TBUT, improved OGD staining, and increased the number of goblet cells. Topical treatment of LA to mice provided decreased expression of MMP-3, MMP-9, TNF-α, and apoptotic corneal epithelium. Topical administration of LA also suppressed the NLRP3 inflammasome in the dry eye disease(DED) murine model by decreasing the expression of NLRP3, ASC, Caspase-1, IL-1β, and IL-18 in the conjunctiva.Conclusion Our findings support the safety and efficacy of LA in the treatment of DED. LA alleviated corneal epithelial damage and suppressed NLRP3 inflammasome-mediated immunity in the conjunctiva in a murine model of DED.

Effect of Tanshinone IIA on LPS-induced inflammatory response in a ROS-NLRP3 inflammasome dependent manner in RAW264.7 cells

Emerging evidence has demonstrated that Tanshinone IIA (Tan IIA) prevents cardiomyocytes injury, cardiac fibroblasts and atherosclerosis. However, the molecular mechanism underlying the effects of Tan IIA is still unclear. To investigate the role of Tan IIA in inflammatory response in a ROS-NLRP3 inflammasome dependent manner, RAW264.7 cells stimulated with LPS were recruited to produce a cell model of inflammatory response. Our results indicated that the production of NO was significantly increased after stimulated by LPS, and Tan IIA treated significantly decreased the level of NO. The mRNA expression of NLRP3, IL-1β and TNF-α was significantly inhibited by Tan IIA compared with LPS treated cells. The protein expression of NLRP3, IKBα, pp65/p65 and pp38/p38 was significantly decreased by Tan IIA, compared with LPS or LPS+ATP stimulated groups. Meanwhile, Tan IIA significantly inhibited the level of ROS induced by LPS+ATP. And NAC, a ROS inhibitor, could also inhibit the protein expression of NLRP3. Based on these findings, it could be speculated that the mechanism underlying the effect of Tan IIA may involve the regulation of ROS-NF-κB/ P38-NLRP3 pathway. This study further characterized the molecular mechanism of Tan IIA, and provided new thoughts to its clinical therapy.

The GSK3b sensing metabolism controls NLRP3 inflammasome activation

OBJECTIVE To identify the role of GSK3 isoform inhibition on inflammasome activation.METHODS The NLRP3 inflammasome was activated by typical LPS/ATP and host-derived metabolites in primary mouse macrophages.The pharmacological inhibition of GSK3 isoforms on inflammasome activation was assayed by quantifying IL-1βin the supernatant,and activated caspase-1in cell lysates using highly selective inhibitors.Further molecular mechanisms were investigated by protein pulldown assay,confocal imaging using forced gene expression system and endogenous protein tagged mouse macrophages.RESULTS Pharmacological inhibition of GSK3-β,but not GSK3-αisoform suppressed NLRP3 inflammasome activation in response to ATP,urate crystal and the microbial alkaloid toxin staurosporine.GSK3-βinhibition did not inhibit melanoma 2(AIM2)inflammasome activation in response to double-stranded DNA(dsDNA)and did not affect non-canonical caspase-11 inflammasome activation.GSK3-βinhibition suppressed high glucose mediated NLRP3 inflammasome activation.Mechanistically,GSK3-βinhibition blocked NLRP3 inflammasome by preventing pro IL-1βtranscription,reducing caspase-1 activation and ASC speck formation.GSK3-βinhibition blocked NLRP3 inflammasome activation without affecting the level of reactive oxygen species(ROS)which is a crucial component in initialing inflammasome activation.Further studies revealed that GSK3-βdirectly binds to ASC by both co-forced expression and endogenous protein level.Interestingly,we found ASC can be glycosylated in response to inflammasome activation,and GSK3-βinhibition reduced ASC glycosylation.Consistently,the O-Glc NAc transferase(OGT)deficient mouse macrophages showed the significant reduction of mature IL-1βsecretion in response to NLRP3 inflammasome activation.CONCLUSION Our results demonstrate a critical role of metabolism-sensing GSK3-βpathway in mediating NLRP3 inflammasome activation,thus defining a new therapeutic target for sterile inflammation.

14-Deoxygarcinol,a polyisoprenylated benzophenone from Garcinia cambogia,ameliorates inflammatory responses in adipose tissue via suppressing NLRP3 inflammasome

OBJECTIVE Interleukin(IL)-1β,one of the principal inflammatory cytokines mainly secreted by monocytes and macrophages,is produced by cleavage of the inactive pro-IL^(-1)βprecursor by caspase-1 via the NLRP3 inflammasome complex.The fruits of Garcinia cambogia(Clusiaceae)are widely developed as health products for anti-obese purpose.14-deoxygarcinol(DOG)is a polyisoprenylated benzophenone from the fruits of G.cambogia,which showed potent anti-inflammatory effect in our previous study.The objective of this study was to explore the anti-inflammatory mechanism of DOG and its roles in alleviating adipose tissue inflammation and insulin resistance.METHODS The anti-inflammatory effect of DOG was evaluated on LPS plus nigericin-induced THP-1 macrophages.The expression of NLRP3 inflammasome complex proteins was analyzed by Western blotting,immunofluorescence staining and co-immunoprecipitation.The pro-inflammatory cytokines levels were determined by ELISA kits.RESULTS DOG increased the expression of Sirtuin 2(SIRT2)deacetylase and enhanced its deacetylating activity to suppress the NLRP3 inflammasome activation and IL^(-1)βsecretion in THP-1 macrophages.Moreover,DOG attenuated macrophage conditioned medium-induced inflammatory responses in adipocytes and blocked THP-1 macrophages migration towards 3T3-L1 adipocytes.CONCLUSION DOG attenuated the inflammatory crosstalk between macrophages and adipocytes through SIRT2-mediated NLRP3 inflammasome inhibition,which might be used for the treatment of adipose tissue inflammation-related metabolic disorders.

Protective action of aspirin and its against endothelial Nlrp3 inflammasome activation in response to LPS stimuli

OBJECTIVE Recent studies have demonstrated that the Nlrp3 inflammasome serve as a central role in the pathogenesis of cardiovascular diseases and endothelial dysfunction occurs in association with several cardiovascular risk factors.Given the demonstrated anti-inflammatory effects of aspirin,the present study was designed to test whether aspirin diminish NLRP3 inflammasome activation and prevent endothelium injury and associated coronary artery damage during LPS.METHODS Mouse carotid arterial endothelial cells(CAECs)were cultured and treated with 0.1-3 mmol·L^(-1) of aspirin in response to LPS(2μg·mL^(-1))stimuli.After 24 h,the Nlrp3 inflammasome complexes consist of varied proteins were analyzed by WB.NO and T-AOC in the supernatant was detected by ELISA.Intracellular reactive oxygen species(ROS)generation for 24 h was observed by DCF fluorescence.The mice were treated with aspirin(12.5 mg·kg^(-1) per day,62.5 mg·kg^(-1) per day,125 mg·kg^(-1) per day)and dexamethasone(0.0182 mg·kg^(-1)per day)for 7 d.The level of IL^(-1)β,IL^(-1)8 protein was detected by ELISA.RESULTS Immunofluorescence results showed the colocalization of Nlrp3 with ASC or caspase 1decrease in a concentration-dependent manner.Meanwhile,the expression of Nlrp3 and caspase 1protein was decreased with the concentration of aspirin,but no changes the expression of ASC protein.Nlrp3 protein levels in CAECs were 0.33-0.8-fold and cle-caspase 1 protein levels in CAECs were 0.48-1-fold compared to those in LPS stimulation when treated with 0.1-3 mmol·L^(-1) aspirin for 24 h(P<0.01).Aspirin significantly antagonized the effect of LPS on NO(1.22-1.91-fold that of LPS stimulation,P<0.01)and T-AOC expression(1.02-1.90-fold that of LPS stimulation,P<0.01).As the different concentration of aspirin treated,the generation of ROS was 0.51-1.10-fold that of LPS stimulation(P<0.01).In vivo data shown the level of IL^(-1)β,IL^(-1)8 protein from serum are in concordance with the level of Nlrp3 inflammasome activation.CONCLUSION We conclude that aspirin has anti-inflammatory properties,protecting CAECs fromLPS-induced injury by inhibition of NLRP3 inflammasome activation through ROS pathway.

Effect of lipoxin receptor agonist BML-111 on the NLRP3 inflammasome after traumatic brain injury in rats

Objective:To investigate the effect of lipoxin receptor agonist BML-111 on the NLRP3 inflammasome after traumatic brain injury in rats.Methods:Sixty male Sprague-Dawley rats,weighing 280~340 g,were randomly divided into 4 groups(n=15):the sham operation group(group Sham),the traumatic brain injury group(group TBI),the BML-111 treatment group(group BML-111),and the BOC-2 treatment group(group BOC-2).The TBI model was prepared by craniocerebral collision,while the rats in group Sham underwent only craniotomy without collision.Acute traumatic brain injury model was prepared in group TBI,BML-111 and BOC-2.The rats in group BOC-2 were intraperitoneally injected with 50μg/kg of BOC-230 min prior to trauma.Then the rats in group BOC-2 and BML-111 were injected intraperitoneally with 1 mg/kg of BML-111 immediately and 24 hours after trauma.The neurological severity scores(NSS)were evaluated at 3 and 7 days after brain trauma.The protein expression levels of NLRP3,Caspase-1-p20 and active Caspase-3 were determined by Western blot.The content of IL-1βand IL-18 was detected by ELISA assays.The apoptotic cells were analyzed by the TUNEL method.Results:Compared with group Sham,the brain water content and NSS scores in group TBI were increased,and the protein levels of NLRP3,Caspase-1-p20,activated Caspase-3,IL-1βand IL-18 as well as TUNEL-positive cells in the cortex were elevated significantly(P<0.05);compared with group TBI,the brain water content and NSS scores in group BML-111 were reduced,and the protein levels of NLRP3,Caspase-1-p20,activated Caspase-3,IL-1βand IL-18 as well as TUNEL-positive cells in the cortex were decreased(P<0.05);Compared with group BML-111,the brain water content and NSS scores in group BOC-2 were increased,and the protein levels of NLRP3,Caspase-1-p20,activated Caspase-3,IL-1βand IL-18 as well as TUNEL-positive cells in the cortex were up-regulated(P<0.05).Conclusions:The lipoxin receptor agonist BML-111 might attenuate traumatic brain injury in rats by inhibiting NLRP3 inflammasome activation.

Research Progress and Ideas on the Anti-liver Fibrosis Effect of Ethnic Medicine Plumbagin Based on microRNAs/TLR4/NF-κB and NLRP3 Inflammasome Activation

The core of hepatic fibrosis is the activation of hepatic stellate cells.Through the lipopolysaccharide/TLR4/MyD88/NF-κB signal transduction pathway,the inflammatory response in the liver is directly enhanced,and then returns to promote the activation of hepatic stellate cells.And TLR4/MyD88/NF-κB signaling pathway can directly regulate the activation of NLRP3 inflammasome and is an important pathway for activating hepatic stellate cells.TLR4/MyD88/NF-κB/NLRP3 inflammasome pathway is regulated by upstream microRNAs.These miRNAs can significantly regulate the inflammatory response of the liver and the activation behavior of hepatic stellate cells,affecting the formation of liver fibrosis.Previous studies have found that the active ingredient of Guangxi specialty ethnic medicine,plumbagin,has a definite anti liver fibrosis effect,but its mechanism of action is not clear.This paper provides a review of the research progress on the above issues,and further research ideas have been derived from this,stating that"the anti liver fibrosis effect of plumbagin is achieved by regulating miRNA/TLR4/MyD88/NF-κB inflammatory pathway and activating downstream NLRP3 inflammasome".

Mechanism of Qishen Decoction inhibition of macrophage M1 type polarization by targeting TGR5-mediated NLRP3 inflammasome

Objective:To observe the effect of Qishen decoction on TGR5-mediated activation of NLRP3 inflammasome,so as to clarify the molecular mechanism of its inhibition of macrophage M1-type polarisation to ameliorate non-alcoholic steatohepatitis;Methods:Mouse macrophage cell line RAW264.7 was randomly divided into a control group,model group,Qishen decoction group,TGR5 agonist group and Qishen decoction+TGR5 agonist group.Except for the control group,the remaining groups were constructed the macrophage NLRP3 activation model by palmitic acid induction,and the corresponding drugs were given to intervene.ELISA was used to detect the levels of TNF-α,IL-6,IL-1βand CXCL2 in macrophage supernatants,flow cytometry was used to detect the expression levels of macrophage polarisation marker molecules CD86 and iNOS,and Western blot was used to detect the expression of the TGR5/STAT1/STAT6 signaling pathway and the expression of NLRP3 inflammasome-associated proteins,respectively.Results:Compared with the control group,the contents of macrophages TNF-α,IL-6,IL-1β,CXCL2 and the proportion of macrophages with positive expression of CD86 and iNOS were significantly increased in the model group,and the differences were all statistically significant(P<0.01).Compared with the model group,the contents of TNF-α,IL-6,IL-1β,CXCL2 and the proportion of macrophages with positive expression of CD86 and iNOS were significantly decreased in the Qishen decoction group,and the differences were all statistically significant(P<0.01).In addition,the expression of NLRP3 and Pro-IL-1βproteins in the macrophage lysate and the expression of Caspase-1 p10,Caspase-1 p20 and IL-1βp17 proteins in the cell supernatant of the model group were significantly increased when compared with the control group,and the differences were all statistically significant(P<0.01).Compared with the model group,the expression of NLRP3 and Pro-IL-1βproteins in macrophage lysate and the expression of Caspase-1 p10,Caspase-1 p20 and IL-1βp17 proteins in cell supernatant of the Qishen decoction were significantly reduced,and the differences were all statistically significant(P<0.01);Conclusion:Qishen decoction can inhibit the activation of NLRP3 inflammasome in macrophages by inhibiting the TGR5/STAT1/STAT6 signaling pathway,thereby inhibiting macrophage M1 polarization and improving inflammatory response.