scholarly journals NEK7-Mediated Activation of NLRP3 Inflammasome Is Coordinated by Potassium Efflux/Syk/JNK Signaling During Staphylococcus aureus Infection

2021 ◽  
Vol 12 ◽  
Author(s):  
Ruiqing Liu ◽  
Yashan Liu ◽  
Chang Liu ◽  
Aijiao Gao ◽  
Lin Wang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Nlrp3 Inflammasome ◽  
Critical Role ◽  
Foodborne Pathogen ◽  
Inflammasome Activation ◽  
Mrna Levels ◽  
Potassium Efflux ◽  
Pyrin Domain ◽  
Subsequent Activation

Staphylococcus aureus (S. aureus) is a foodborne pathogen that causes severe diseases, such as endocarditis, sepsis, and bacteremia. As an important component of innate immune system, the NLR family pyrin domain-containing 3 (NLRP3) inflammasome plays a critical role in defense against pathogen infection. However, the cellular mechanism of NLRP3 inflammasome activation during S. aureus infection remains unknown. In the present study, we found that spleen tyrosine kinase (Syk) and c-Jun N-terminal kinase (JNK) were rapidly phosphorylated during S. aureus infection. Moreover, a Syk/JNK inhibitor and Syk/JNK siRNA not only reduced NLRP3 inflammasome-associated molecule expression at the protein and mRNA levels, apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC) speck formation, and interleukin-1β (IL-1β), and IL-18 release but also rescued the decreased NIMA-related kinase 7 (NEK7) expression level following suppression of the NEK7-NLRP3 interaction in macrophages. Interestingly, Syk/JNK phosphorylation levels and NLRP3 inflammasome-associated molecule expression were decreased by blockade of K+ efflux. Furthermore, activation of the NLRP3 inflammasome and a lower NEK7 protein level were found in vivo upon S. aureus infection. Taken together, our data indicated that S. aureus infection induces a K+ efflux/Syk/JNK/NEK7-NLRP3 signaling pathway and the subsequent activation of the NLRP3 inflammasome for the release of proinflammatory cytokines. This study expands our understanding of the basic molecular mechanism regulating inflammation and provides potential value for anti-infective drug development against S. aureus infection.

scholarly journals The Roles of Endoplasmic Reticulum in NLRP3 Inflammasome Activation

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1219 ◽  
Author(s):  
Yang Zhou ◽  
Zhizi Tong ◽  
Songhong Jiang ◽  
Wenyan Zheng ◽  
Jianjun Zhao ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Nlrp3 Inflammasome ◽  
Critical Role ◽  
Immune Defense ◽  
Inflammasome Activation ◽  
Nucleotide Binding Domain ◽  
Cholesterol Trafficking ◽  
Pyrin Domain ◽  
Nlrp3 Inflammasome Activation ◽  
Molecular Patterns

The NLRP3 (nucleotide-binding domain, leucine-rich-repeat-containing family, pyrin domain-containing 3) inflammasome senses pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), and activates caspase-1, which provokes release of proinflammatory cytokines such as interleukin-1β (IL-1β) and IL-18 as well as pyroptosis to engage in innate immune defense. The endoplasmic reticulum (ER) is a large and dynamic endomembrane compartment, critical to cellular function of organelle networks. Recent studies have unveiled the pivotal roles of the ER in NLRP3 inflammasome activation. ER–mitochondria contact sites provide a location for NLRP3 activation, its association with ligands released from or residing in mitochondria, and rapid Ca2+ mobilization from ER stores to mitochondria. ER-stress signaling plays a critical role in NLRP3 inflammasome activation. Lipid perturbation and cholesterol trafficking to the ER activate the NLRP3 inflammasome. These findings emphasize the importance of the ER in initiation and regulation of the NLRP3 inflammasome.

scholarly journals Induction of NLRP3 Inflammasome Activation by Heme in Human Endothelial Cells

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Judit Erdei ◽  
Andrea Tóth ◽  
Enikő Balogh ◽  
Benard Bogonko Nyakundi ◽  
Emese Bányai ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Nlrp3 Inflammasome ◽  
Structural Integrity ◽  
Umbilical Vein ◽  
Critical Role ◽  
Protoporphyrin Ix ◽  
Inflammasome Activation ◽  
Pyrin Domain ◽  
Nlrp3 Inflammasome Activation ◽  
Umbilical Vein Endothelial Cells

Hemolytic or hemorrhagic episodes are often associated with inflammation even when infectious agents are absent suggesting that red blood cells (RBCs) release damage-associated molecular patterns (DAMPs). DAMPs activate immune and nonimmune cells through pattern recognition receptors. Heme, released from RBCs, is a DAMP and induces IL-1βproduction through the activation of the nucleotide-binding domain and leucine-rich repeat-containing family and pyrin domain containing 3 (NLRP3) in macrophages; however, other cellular targets of heme-mediated inflammasome activation were not investigated. Because of their location, endothelial cells can be largely exposed to RBC-derived DAMPs; therefore, we investigated whether heme and other hemoglobin- (Hb-) derived species induce NLRP3 inflammasome activation in these cells. We found that heme upregulated NLRP3 expression and induced active IL-1βproduction in human umbilical vein endothelial cells (HUVECs). LPS priming largely amplified the heme-mediated production of IL-1β. Heme administration into C57BL/6 mice induced caspase-1 activation and cleavage of IL-1βwhich was not observed in NLRP3−/−mice. Unfettered production of reactive oxygen species played a critical role in heme-mediated NLRP3 activation. Activation of NLRP3 by heme required structural integrity of the heme molecule, as neither protoporphyrin IX nor iron-induced IL-1βproduction. Neither naive nor oxidized forms of Hb were able to induce IL-1βproduction in HUVECs. Our results identified endothelial cells as a target of heme-mediated NLRP3 activation that can contribute to the inflammation triggered by sterile hemolysis. Thus, understanding the characteristics and cellular counterparts of RBC-derived DAMPs might allow us to identify new therapeutic targets for hemolytic diseases.

scholarly journals The selective NLRP3 inhibitor MCC950 hinders atherosclerosis development by attenuating inflammation and pyroptosis in macrophages

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wenyun Zeng ◽  
Danbin Wu ◽  
Yingxin Sun ◽  
Yanrong Suo ◽  
Qun Yu ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
High Fat Diet ◽  
In Vitro Study ◽  
Inflammasome Activation ◽  
Mrna Levels ◽  
High Fat ◽  
Nlrp3 Inflammasome Activation ◽  
Atherosclerosis Development

AbstractNLRP3 inflammasome is a vital player in macrophages pyroptosis, which is a type of proinflammatory cell-death and takes part in the pathogenesis of atherosclerosis. In this study, we used apoE−/− mice and ox-LDL induced THP-1 derived macrophages to explore the mechanisms of MCC950, a selective NLRP3 inhibitor in treating atherosclerosis. For the in vivo study, MCC950 was intraperitoneal injected to 8-week-old apoE−/− mice fed with high-fat diet for 12 weeks. For the in vitro study, THP-1 derived macrophages were treated with ox-LDL and MCC950 for 48 h. MCC950 administration reduced plaque areas and macrophages contents, but did not improve the serum lipid profiles in aortic root of apoE−/− mice. MCC950 inhibited the activation of NLRP3/ASC/Caspase-1/GSDMD-N axis, and alleviated macrophages pyroptosis and the production of IL-1β and IL-18 both in aorta and in cell lysates. However, MCC950 did not affect the expression of TLR4 or the mRNA levels of NLRP3 inflammasome and its downstream proteins, suggesting that MCC950 had no effects on the priming of NLRP3 inflammasome activation in macrophages. The anti-atherosclerotic mechanisms of MCC950 on attenuating macrophages inflammation and pyroptosis involved in inhibiting the assembly and activation of NLRP3 inflammasome, rather than interrupting its priming.

NLRP3 inflammasome is involved in uterine activation for labor at term and preterm

Reproduction ◽  
2021 ◽  
Vol 162 (6) ◽  
pp. 449-460
Author(s):  
Zixi Chen ◽  
Yali Shan ◽  
Xingji You ◽  
Hang Gu ◽  
Chen Xu ◽  
...  
Keyword(s):  
Mouse Model ◽  
Nlrp3 Inflammasome ◽  
Inflammatory Diseases ◽  
Critical Role ◽  
Inflammasome Activation ◽  
Pyrin Domain ◽  
Nlrp3 Inflammasome Activation ◽  
Pregnant Mice ◽  
Labor Onset

The nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome plays a critical role in various inflammatory diseases. We sought to investigate the role of NLRP3 inflammasome in uterine activation for labor at term and preterm. We found that NLRP3 inflammasome was activated in the myometrium tissues obtained from the pregnant women undergoing labor at term (TL) compared with those not undergoing labor (TNL) at term. NLRP3 inflammasome was also activated in amnion and chorion-deciduas in TL and preterm labor (PTL) groups. In the mouse model, uterine NLRP3 inflammasome and nuclear factor kappaB (NF-κB) were activated toward term and during labor. Treatment of pregnant mice with lipopolysaccharide (LPS) and RU38486 induced preterm birth (PTB) and also promoted uterine NLRP3 inflammasome and NF-κB activation. Treatment of pregnant mice with NLRP3 inflammasome inhibitor BAY11-7082 and MCC950 delayed the onset of labor and suppressed NLRP3 inflammasome and NF-κB activation in uterus. MCC950 postponed labor onset of the mice with LPS and RU38486 treatment and inhibited NLRP3 inflammasome activation in uterus. Our data provide the evidence that NLRP3 inflammasome is involved in uterine activation for labor onset in term and PTB in humans and mouse model.

scholarly journals Dopamine Signaling Modulates Microglial NLRP3 Inflammasome Activation: Implications for Parkinson’s Disease

2021 ◽  
Author(s):  
Adrianne F. Pike ◽  
Francesca Longhena ◽  
Gaia Faustini ◽  
Jean-Marc van Eik ◽  
Iris Gombert ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Nlrp3 Inflammasome ◽  
Critical Role ◽  
Inflammasome Activation ◽  
Human Microglia ◽  
Dopaminergic Neurodegeneration ◽  
Nlrp3 Inflammasome Activation ◽  
Dopamine Signaling

Abstract Background: Parkinson’s disease (PD) is characterized by the loss of nigral dopaminergic neurons leading to impaired striatal dopamine signaling, α-synuclein- (α-syn-) rich inclusions, and neuroinflammation. Degenerating neurons are surrounded by activated microglia with increased secretion of interleukin-1β (IL-1β), driven largely by the NLRP3 inflammasome. A critical role for microglial NLRP3 inflammasome activation in the progression of both dopaminergic neurodegeneration and α-syn pathology has been demonstrated in parkinsonism mouse models. Fibrillar α-syn activates this inflammasome in mouse and human macrophages, and we have shown previously that the same holds true for primary human microglia. Dopamine blocks microglial NLRP3 inflammasome activation in the MPTP model, but its effects in this framework, highly relevant to PD, remain unexplored in primary human microglia and in other in vivo parkinsonism models. Methods: Biochemical techniques including quantification of IL-1β secretion and confocal microscopy were employed to gain insight into dopamine signaling-mediated inhibition of the NLRP3 inflammasome mechanism in primary human microglia and the SYN120 transgenic mouse model. Dopamine and related metabolites were applied to human microglia together with various inflammasome activating stimuli. The involvement of the receptors through which these catecholamines were predicted to act were assessed with agonists in both species. Results: We show in primary human microglia that dopamine, L-DOPA, and high extracellular K+, but not norepinephrine and epinephrine, block canonical, non-canonical, and α-syn-mediated NLRP3 inflammasome-driven IL-1β secretion. This suggests that dopamine acts as an inflammasome inhibitor in human microglia. Accordingly, we provide evidence that dopamine exerts its inhibitory effect through dopamine receptor D1 and D2 (DRD1 and DRD2) signaling. We also show that aged mice transgenic for human C-terminally truncated (1-120) α-syn (SYN120 tg mice) display increased NLRP3 inflammasome activation in comparison to WT mice that is diminished upon DRD1 agonism. Conclusions: Dopamine inhibits canonical, non-canonical, and α-syn-mediated activation of the NLRP3 inflammasome in primary human microglia, as does high extracellular K+. We suggest that dopamine serves as an endogenous repressor of the K+ efflux-dependent microglial NLRP3 inflammasome activation that contributes to dopaminergic neurodegeneration in PD, and that this reciprocation may account for the specific vulnerability of these neurons to disease pathology.

scholarly journals NLRP3 Inflammasome Contributes to Host Defense Against Talaromyces marneffei Infection

2021 ◽  
Vol 12 ◽  
Author(s):  
Haiyan Ma ◽  
Jasper F. W. Chan ◽  
Yen Pei Tan ◽  
Lin Kui ◽  
Chi-Ching Tsang ◽  
...  
Keyword(s):  
Host Defense ◽  
Nlrp3 Inflammasome ◽  
Critical Role ◽  
Cell Types ◽  
Inflammasome Activation ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation ◽  
Fungal Load ◽  
Different Cell Types

Talaromyce marneffei is an important thermally dimorphic pathogen causing disseminated mycoses in immunocompromised individuals in southeast Asia. Previous studies have suggested that NLRP3 inflammasome plays a critical role in antifungal immunity. However, the mechanism underlying the role of NLRP3 inflammasome activation in host defense against T. marneffei remains unclear. We show that T. marneffei yeasts but not conidia induce potent IL-1β production. The IL-1β response to T. marneffei yeasts is differently regulated in different cell types; T. marneffei yeasts alone are able to induce IL-1β production in human PBMCs and monocytes, whereas LPS priming is essential for IL-1β response to yeasts. We also find that Dectin-1/Syk signaling pathway mediates pro-IL-1β production, and NLRP3-ASC-caspase-1 inflammasome is assembled to trigger the processing of pro-IL-1β into IL-1β. In vivo, mice deficient in NLRP3 or caspase-1 exhibit higher mortality rate and fungal load compared to wild-type mice after systemic T. marneffei infection, which correlates with the diminished recruitment of CD4 T cells into granulomas in knockout mice. Thus, our study first demonstrates that NLRP3 inflammasome contributes to host defense against T. marneffei infection.

scholarly journals NLRP3 inflammasome contributes to host defense against Talaromyces marneffei infection

2020 ◽  
Author(s):  
Haiyan Ma ◽  
Jasper FW Chan ◽  
Yen Pei Tan ◽  
Lin Kui ◽  
Chi-Ching Tsang ◽  
...  
Keyword(s):  
Host Defense ◽  
Nlrp3 Inflammasome ◽  
Immune Cell ◽  
Critical Role ◽  
Cell Types ◽  
Inflammasome Activation ◽  
Talaromyces Marneffei ◽  
Nlrp3 Inflammasome Activation ◽  
Fungal Load

AbstractTalaromyces marneffei is an important thermally dimorphic pathogen causing disseminated mycoses in immunocompromised individuals in southeast Asia. Previous study has suggested that NLRP3 inflammasome plays a critical role in antifungal immunity. However, the mechanism underlying the role of NLRP3 inflammasome activation in host defense against T. marneffei remains unclear. We show that T. marneffei yeasts but not conidia induce potent IL-1β response, which is differentially regulated in discrete immune cell types. Dectin-1/Syk signaling pathway mediates pro-IL-1β production, and NLRP3 inflammasome is activated to trigger the processing of pro-IL-1β into IL-1β. The activated NLRP3 inflammasome partially promotes Th1 and Th17 immune responses against T. marneffei yeasts. In vivo, mice with NLRP3 or caspase-1 deficiency exhibit higher mortality rate and fungal load compared to wild-type mice. Herein, our study provides the first evidence that NLRP3 inflammasome contributes to host defense against T. marneffei infection, which may have implications for future antifungal therapeutic designs.

scholarly journals The E3 Ubiquitin Ligase TRIM65 Negatively Regulates Inflammasome Activation Through Promoting Ubiquitination of NLRP3

2021 ◽  
Vol 12 ◽  
Author(s):  
Tiantian Tang ◽  
Ping Li ◽  
Xinhui Zhou ◽  
Rui Wang ◽  
Xiuqin Fan ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Inflammatory Diseases ◽  
Critical Role ◽  
Neutrophil Migration ◽  
Inflammasome Activation ◽  
Regulation Mechanism ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation

The dysregulation of NLRP3 inflammasome plays a critical role in pathogenesis of various human inflammatory diseases, thus NLRP3 inflammasome activation must be tightly controlled at multiple levels. However, the underlying mechanism regulating NLRP3 inflammasome activation remains unclear. Herein, the effects of Tripartite motif-containing protein 65 (TRIM65) on NLRP3 inflammasome activation and the underlying molecular mechanism were investigated in vitro and in vivo. Inhibition or deletion of Trim65 could significantly strengthen agonist induced NLRP3 inflammasome activation in THP-1 cells and BMDMs, indicated by increased caspase-1 activation and interleukin-1β secretion. However, TRIM65 had no effect on poly (dA: dT)-induced AIM2 inflammasome activation or flagellin-induced IPAF inflammasome activation. Mechanistically, immunoprecipitation assays demonstrated that TRIM65 binds to NACHT domain of NLRP3, promotes lys48- and lys63- linked ubiquitination of NLRP3 and restrains the NEK7-NLRP3 interaction, thereby inhibiting NLRP3 inflammasome assembly, caspase-1 activation, and IL-1β secretion. In vivo, three models of inflammatory diseases were used to confirm the suppression role of TRIM65 in NLRP3 inflammasome activation. TRIM65-deficient mice had a higher production of IL-1β induced by lipopolysaccharide in sera, and more IL-1β secretion and neutrophil migration in the ascites, and more severity of joint swelling and associated IL-1β production induced by monosodium urate, suggesting that TRIM65 deficiency was susceptible to inflammation. Therefore, the data elucidate a TRIM65-dependent negative regulation mechanism of NLRP3 inflammasome activation and provide potential therapeutic strategies for the treatment of NLRP3 inflammasome-related diseases.

scholarly journals Anthocyanins from Hibiscus syriacus L. Inhibit NLRP3 Inflammasome in BV2 Microglia Cells by Alleviating NF-κB- and ER Stress-Induced Ca2+ Accumulation and Mitochondrial ROS Production

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Ilandarage Menu Neelaka Molagoda ◽  
Kyoung Tae Lee ◽  
Yung Hyun Choi ◽  
Jayasingha Arachchige Chathuranga Chanaka Jayasingha ◽  
Gi-Young Kim
Keyword(s):  
Er Stress ◽  
Signaling Pathway ◽  
Nlrp3 Inflammasome ◽  
Early Stage ◽  
Nuclear Factor Κb ◽  
Inflammasome Activation ◽  
Pyrin Domain ◽  
Bv2 Microglia ◽  
Hibiscus Syriacus

Anthocyanins from the petals of Hibiscus syriacus L. (PS) possess anti-inflammatory, antioxidant, and antimelanogenic activities. However, it remains unclear whether PS inhibit the NLR family pyrin domain-containing 3 (NLRP3) inflammasome activation and assembly. This study is aimed at investigating whether PS downregulate NLRP3-mediated inflammasome by inhibiting nuclear factor-κB (NF-κB) and endoplasmic reticulum (ER) stress. BV2 microglia cells were treated with PS in the presence of lipopolysaccharide and adenosine triphosphate (LPS/ATP), and the NLRP3-related signaling pathway was investigated. In this study, we found that LPS/ATP treatment activated the NLRP3 inflammasome, which resulted in the release of interleukin-1β (IL-1β) and IL-18. Meanwhile, PS reduced LPS/ATP-mediated NLRP3 inflammasome at 12 h by inhibiting ER stress-mediated Ca2+ accumulation and subsequent mitochondrial reactive oxygen species (mtROS) production, which, in turn, decreased IL-1β and IL-18 release. Furthermore, PS inhibited the NLRP3 inflammasome 1 h after LPS/ATP treatment by suppressing the NF-κB pathway, which downregulated Ca2+ accumulation and mtROS production. These data showed that PS negatively regulated activation of the NLRP3 inflammasome in a time-different manner by inhibiting the NF-κB signaling pathway in the early stage and the ER stress response in the late stage. The pathways shared Ca2+ accumulation-mediated mtROS production, which was significantly inhibited in the presence of PS. In conclusion, our results suggested that PS has potential as a supplement against NLRP3 inflammasome-related inflammatory disorders; nevertheless, further studies are needed to determine the effect of PS in the noncanonical NLRP3 inflammasome pathways and pathological conditions in vivo.

scholarly journals Dopamine Signaling Modulates Microglial NLRP3 Inflammasome Activation: Implications for Parkinson’s Disease

2021 ◽  
Author(s):  
Adrianne Frances Pike ◽  
Francesca Longhena ◽  
Gaia Faustini ◽  
Jean-Marc van Eik ◽  
Iris Gombert ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Nlrp3 Inflammasome ◽  
Critical Role ◽  
Inflammasome Activation ◽  
Human Microglia ◽  
Dopaminergic Neurodegeneration ◽  
Nlrp3 Inflammasome Activation ◽  
Dopamine Signaling

Abstract Background: Parkinson’s disease (PD) is characterized by the loss of nigral dopaminergic neurons leading to impaired striatal dopamine signaling, α-synuclein- (α-syn-) rich inclusions, and neuroinflammation. Degenerating neurons are surrounded by activated microglia with increased secretion of interleukin-1β (IL-1β), driven largely by the NLRP3 inflammasome. A critical role for microglial NLRP3 inflammasome activation in the progression of both dopaminergic neurodegeneration and α-syn pathology has been demonstrated in parkinsonism mouse models. Fibrillar α-syn activates this inflammasome in mouse and human macrophages, and we have shown previously that the same holds true for primary human microglia. Dopamine blocks microglial NLRP3 inflammasome activation in the MPTP model, but its effects in this framework, highly relevant to PD, remain unexplored in primary human microglia and in other in vivo parkinsonism models. Methods: Biochemical techniques including quantification of IL-1β secretion and confocal microscopy were employed to gain insight into dopamine signaling-mediated inhibition of the NLRP3 inflammasome mechanism in primary human microglia and the SYN120 transgenic mouse model. Dopamine and related metabolites were applied to human microglia together with various inflammasome activating stimuli. The involvement of the receptors through which these catecholamines were predicted to act were assessed with agonists in both species. Results: We show in primary human microglia that dopamine, L-DOPA, and high extracellular K+, but not norepinephrine and epinephrine, block canonical, non-canonical, and α-syn-mediated NLRP3 inflammasome-driven IL-1β secretion. This suggests that dopamine acts as an inflammasome inhibitor in human microglia. Accordingly, we provide evidence that dopamine exerts its inhibitory effect through dopamine receptor D1 and D2 (DRD1 and DRD2) signaling. We also show that aged mice transgenic for human C-terminally truncated (1-120) α-syn (SYN120 tg mice) display increased NLRP3 inflammasome activation in comparison to WT mice that is diminished upon DRD1 agonism. Conclusions: Dopamine inhibits canonical, non-canonical, and α-syn-mediated activation of the NLRP3 inflammasome in primary human microglia, as does high extracellular K+. We suggest that dopamine serves as an endogenous repressor of the K+ efflux-dependent microglial NLRP3 inflammasome activation that contributes to dopaminergic neurodegeneration in PD, and that this reciprocation may account for the specific vulnerability of these neurons to disease pathology.

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