miR-1929-3p Overexpression Alleviates Murine Cytomegalovirus-Induced Hypertensive Myocardial Remodeling by Suppressing Ednra/NLRP3 Inflammasome Activation

MicroRNAs (miRNAs) play crucial roles in the development of essential hypertension (EH). Previously, we found that the expression of miR-1929-3p was decreased in C57BL/6 mice with hypertension induced by murine cytomegalovirus (MCMV). In this study, we explored the role of miR-1929-3p in hypertension myocardial remodeling in MCMV-infected mice. First, we measured MCMV DNA and host IgG and IgM after infection and determined the expression of miR-1929-3p and its target gene endothelin A receptor (Ednra) mRNA in the myocardium of mice. Then, we performed invasive blood pressure (BP) monitoring. Heart-to-body weight ratio (HW/BW%), along with mRNA levels of B-type natriuretic peptide (BNP) and beta myosin heavy chain (β-MHC), revealed myocardial remodeling. Hematoxylin/eosin and Masson’s trichrome staining indicated morphological changes in the myocardium. Cardiac function was assessed via echocardiography. Moreover, MCMV-infected mice were injected with recombinant adeno-associated virus- (rAAV-) miR-1929-3p overexpression vector. Immunohistochemistry and western blotting showed the expression of Ednra and the activation of NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome. And enzyme-linked immunosorbent assay (ELISA) revealed the concentrations of endothelin-1 (ET-1), interleukin-1β (IL-1β), and interleukin-18 (IL-18). In this study, we found that decreased expression of miR-1929-3p in MCMV-infected mice induced high BP and further development of myocardial remodeling cardiac function injury through increased expression of Ednra. Strikingly, overexpression of miR-1929-3p ameliorated these pathological changes of the heart. The positive effect was shown to be associated with inhibition of NLRP3 inflammasome activation and decreased expression of key proinflammatory cytokine IL-1β. Collectively, these results indicate that miR-1929-3p overexpression may effectively alleviate EH myocardial remodeling by suppressing Ednra/NLRP3 inflammasome activation in MCMV-infected mice.

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Eff ects of hyperbaric oxygen on NLRP3 infl ammasome activation in the brain aft er carbon monoxide poisoning

Undersea and Hyperbaric Medicine ◽

10.22462/10.12.2020.10 ◽

2020 ◽

pp. 607-619

Author(s):

Ya’nan Qi ◽

◽

Zhibao Guo ◽

Huijun Hu ◽

Xiang’en Meng ◽

...

Keyword(s):

Carbon Monoxide ◽

Nadph Oxidase ◽

Hyperbaric Oxygen ◽

Nlrp3 Inflammasome ◽

Carbon Monoxide Poisoning ◽

Enzyme Linked Immunosorbent Assay ◽

Inflammasome Activation ◽

Protein Levels ◽

Nlrp3 Inflammasome Activation ◽

Myelin Injury

Neuroinflammation plays an important role in brain damage after acute carbon monoxide poisoning (ACOP). The nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing (NLRP) 3 inflammasome triggers the activation of inflammatory caspases and maturation of interleukin (IL)-1β and -18, and has been linked to various human autoinflammatory and autoimmune diseases. In this study we investigated the effects of hyperbaric oxygen (HBO2) on NLRP3 inflammasome activation after ACOP. Mice were randomly divided into four groups: sham group (exposure to normobaric air – i.e., 21% O2 at 1 atmosphere absolute); HBO2-only group; CO + normobaric air group; and CO + HBO2 group. Cognitive function was evaluated with the Morris water maze; myelin injury was assessed by Fluoro-Myelin GreenTM fluorescent myelin staining and myelin basic protein (MBP) immunostaining; and mRNA and protein levels of NLRP3 inflammasome complex proteins were measured by quantitative real-time PCR and Western blot, respectively. Additionally, serum and brain levels of IL-1β and -18 and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase were determined by enzyme-linked immunosorbent assay. It was found that HBO2 improved learning and memory, and alleviated myelin injury in mice subjected to acute CO exposure. Furthermore, HBO2 decreased NLRP3, absent in melanoma 2 (AIM2), caspase-1, and apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain mRNA and protein levels, and reduced brain and serum concentrations of IL-1β and -18 and NADPH oxidase. These results indicate that HBO2 suppresses the inflammatory response after ACOP by blocking NLRP3 inflammasome activation, thereby alleviating cognitive deficits.

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Role of ASM/Cer/TXNIP signaling module in the NLRP3 inflammasome activation

Lipids in Health and Disease ◽

10.1186/s12944-021-01446-4 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Jianjun Jiang ◽

Yining Shi ◽

Jiyu Cao ◽

Youjin Lu ◽

Gengyun Sun ◽

...

Keyword(s):

Signaling Pathway ◽

Nlrp3 Inflammasome ◽

Mrna Level ◽

Scavenger Receptor ◽

Nuclear Factor Κb ◽

Inflammasome Activation ◽

Mrna Levels ◽

Irreversible Inhibitor ◽

Nlrp3 Inflammasome Activation

Abstract Background This study aimed to explore the effects of ceramide (Cer) on NLRP3 inflammasome activation and their underlying mechanisms. Methods Lipopolysaccharide (LPS)/adenosine triphosphate (ATP)-induced NLRP3 inflammasome activation in J774A.1 cells and THP-1 macrophages was used as an in vitro model of inflammation. Western blotting and real-time PCR (RT-PCR) were used to detect the protein and mRNA levels, respectively. IL-1β and IL-18 levels were measured by ELISA. ASM assay kit and immunofluorescence were used to detect ASM activity and Cer content. Results Imipramine, a well-known inhibitor of ASM, significantly inhibited LPS/ATP-induced activity of ASM and the consequent accumulation of Cer. Additionally, imipramine suppressed the LPS/ATP-induced expression of thioredoxin interacting protein (TXNIP), NLRP3, caspase-1, IL-1β, and IL-18 at the protein and mRNA level. Interestingly verapamil, a TXNIP inhibitor, suppressed LPS/ATP-induced activation of TXNIP/NLRP3 inflammasome but did not affect LPS/ATP-induced ASM activation and Cer formation. TXNIP siRNA and verapamil inhibited C2-Cer-induced upregulation of TXNIP and activation of the NLRP3 inflammasome. In addition, the pretreatment of cells with sulfo-N-succinimidyl oleate (SSO), an irreversible inhibitor of the scavenger receptor CD36, blocked Cer-induced upregulation of nuclear factor-κB (NF-κB) activity, TXNIP expression, and NLRP3 inflammasome activation. Inhibition of NF-κB activation by SN50 prevented Cer-induced upregulation of TXNIP and activation of the NLRP3 inflammasome but did not affect CD36 expression. Conclusion This study demonstrated that the ASM/Cer/TXNIP signaling pathway is involved in NLRP3 inflammasome activation. The results documented that the CD36-dependent NF-κB-TXNIP signaling pathway plays an essential role in the Cer-induced activation of NLRP3 inflammasomes in macrophages.

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Yanghe Decoction Suppresses the Experimental Autoimmune Thyroiditis in Rats by Improving NLRP3 Inflammasome and Immune Dysregulation

Frontiers in Pharmacology ◽

10.3389/fphar.2021.645354 ◽

2021 ◽

Vol 12 ◽

Author(s):

Bing’e Ma ◽

Dexuan Chen ◽

Yangjing Liu ◽

Zhengping Zhao ◽

Jianhua Wang ◽

...

Keyword(s):

Western Blot ◽

Autoimmune Thyroiditis ◽

Nlrp3 Inflammasome ◽

Immune Dysregulation ◽

Enzyme Linked Immunosorbent Assay ◽

Inflammasome Activation ◽

Mrna Levels ◽

Rt Pcr ◽

Experimental Autoimmune Thyroiditis ◽

Experimental Autoimmune

Inflammation is an important contributor to autoimmune thyroiditis. Yanghe decoction (YH) is a traditional Chinese herbal formulation which has various anti-inflammatory effects. It has been used for the treatment of autoimmune diseases such as ankylosing spondylitis In this study we aimed to investigate the effects of YH on autoimmune thyroiditis in a rat model and elucidate the underlying mechanisms. The experimental autoimmune thyroiditis (EAT) model was established by thyroglobulin (pTG) injections and excessive iodine intake. Thyroid lesions were observed using hematoxylin and eosin (H and E) staining and serum TgAb, TPOAb, TSH, T3, and T4 levels were measured by enzyme-linked immunosorbent assay IL-35 levels were evaluated using real-time polymerase chain reaction (RT-PCR) and Th17/Treg balance in peripheral blood mononuclear cells (PBMCs) was determined by flow cytometry and RT-PCR. Changes in Wnt/β-catenin signaling were evaluated using Western blot. Immunofluorescence staining and western blot were employed to examine NLRP3 inflammasome activation in the thyroid. YH minimized thyroid follicle injury and decreased concentrations of serum TgAb, TPOAb, TSH, T3, and T4 in EAT model. The mRNA of IL-35 was increased after YH treatment. YH also increased the percentage of Treg cells, and decreased Th17 proportion as well as Th17/Treg ratio in PBMCs. Meanwhile, the mRNA levels of Th17 related cytokines (RORγt, IL-17A, IL-21, and IL-22) were suppressed and Treg related cytokines (FoxP3, TGF-β, and IL-10) were promoted in PBMCs. Additionally, the protein expressions of Wnt-1 and β-catenin were unregulated after YH treatment. NLRP3 immunostaining signal and protein levels of IL-17, p-NF-κB, NLRP3, ASC, cleaved-Caspase-1, cleaved-IL-1β, and IL-18 were downregulated in the thyroid after YH intervention. Overall, the present study demonstrated that YH alleviated autoimmune thyroiditis in rats by improving NLRP3 inflammasome and immune dysregulation.

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

Scientific Reports ◽

10.1038/s41598-021-98437-3 ◽

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.

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Modulation of RAS and PI3-AKT pathway by Stavudine (d4T) in PBMC of Alzheimer’s Disease Patients

10.21203/rs.3.rs-23119/v1 ◽

2020 ◽

Author(s):

Francesca La Rosa ◽

Chiara Paola Zoia ◽

Chiara Bazzini ◽

Alessandra Bolognini ◽

Saresella Marina ◽

...

Keyword(s):

Proinflammatory Cytokines ◽

Nlrp3 Inflammasome ◽

Molecular Mechanisms ◽

Beclin 1 ◽

Enzyme Linked Immunosorbent Assay ◽

Inflammasome Activation ◽

Beneficial Effects ◽

Nlrp3 Inflammasome Activation ◽

Chaperone Mediated Autophagy ◽

Inflammasome Activity

Abstract Background Aβ42-deposition plays a pivotal role in AD-pathogenesis by inducing the activation of microglial cells and neuroinflammation. This process is antagonized by microglia-mediated clearance of Aβ plaques. Activation of the NLRP3 inflammasome is involved in neuroinflammation and in the impairments of Aβ-plaques clearance. Stavudine (d4T) on the other hand down-regulates the NLRP3 inflammasome and stimulates autophagy-mediated Aβ-clearing in a TPH-1 cell line model. Methods We explored the effect of d4T on Aβ- autophagy using PBMC of AD patients that were primed with LPS and stimulated with Aβ in the absence/presence of d4T. We analyzed the NLRP3 inflammasome activity by measuring NLRP3-ASC complexes formation by AMNIS Flow-sight and pro-inflammatory cytokines (IL-1β, IL-18 and Caspase-1) production by enzyme-linked immunosorbent assay (ELISA). Western blot analyses were used to measure phosphorylation and protein expression of p38, CREB, ERK and AKT, p70, LAMP 2A, beclin-1 and Bax. Results data showed that d4T: 1) down regulates NLRP3 inflammasome activation and the production of down-stream proinflammatory cytokines even in PBMC; 2) stimulates the phosphorylation of AKT, ERK, p70 as well as LAMP2A production, but does modulate beclin-1, suggesting a selective effect of this compound on chaperone-mediated autophagy (CMA); 3) up regulates p-CREB and BAX, possibly diminishing Aβ–mediated cytotoxicity; and 4) reduces the phosphorylation of p-38, a protein involved in the production of proinflammatory cytokines. Conclusions d4T reduces the activation of the NLRP3 inflammasome and stimulates CMA autophagy as well as molecular mechanisms that modulate cytotoxicity and reduce inflammation in cells of AD patients. It might be interesting to verify the possibly beneficial effects of d4T in the clinical scenario.

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Effects of the TLR4/Myd88/NF-κB Signaling Pathway on NLRP3 Inflammasome in Coronary Microembolization-Induced Myocardial Injury

Cellular Physiology and Biochemistry ◽

10.1159/000490866 ◽

2018 ◽

Vol 47 (4) ◽

pp. 1497-1508 ◽

Cited By ~ 28

Author(s):

Qiang Su ◽

Lang Li ◽

Yuhan Sun ◽

Huafeng Yang ◽

Ziliang Ye ◽

...

Keyword(s):

Inflammatory Response ◽

Cardiac Function ◽

Nlrp3 Inflammasome ◽

Myocardial Injury ◽

Neonatal Rat ◽

Myocardial Inflammation ◽

Inflammasome Activation ◽

Coronary Microembolization ◽

Coronary Syndrome ◽

Nlrp3 Inflammasome Activation

Background/Aims: Coronary microembolization (CME) is a common complication of acute coronary syndrome (ACS) and percutaneous coronary intervention (PCI); Myocardial inflammation, caused by CME, is the main cause of cardiac injury. TLR4/MyD88/NF-κB signaling plays an important role in the development of myocardial inflammation, but its effects on CME remain unclear. To assess the cardiac protective effects of TAK-242 (TLR4 specific inhibitor) on CME-induced myocardial injury, and explore the underlying mechanism. Methods: Cardiac function, serum c-troponin I level, microinfarct were examined by cardiac ultrasound, myocardial enzyme assessment, HBFP staining. The levels of TLR4/MyD88/NF-κB signaling and NLRP3 inflammasome pathway were detected by ELISA, qRT-PCR and western blot. Results: The results showed inflammatory responses in the myocardium after CME, with increased expression levels of pro-inflammatory factors TNF-α, IL-1β and IL-18. Meanwhile, TLR4/MyD88/NF-κB signaling and the NLRP3 inflammasome were involved in the inflammatory process. TAK-242 administration before CME effectively inhibited the inflammatory response in the rat myocardium after CME and reduced myocardial injury, mainly by inhibiting TLR4/ MyD88/NF-κB signaling and reducing NLRP3 inflammasome activation. In addition, in vitro assays with neonatal rat cardiomyocytes further confirmed that TLR4/MyD88/NF-κB signaling was significantly activated in the inflammatory response of LPS-induced cardiomyocytes, via activation of the NLRP3 inflammasome. Inhibition of TLR4/MyD88/NF-κB signaling resulted in increased survival of cardiomyocytes mainly by reducing the release of inflammatory cytokines and decreasing NLRP3 inflammasome activation. Conclusions: TLR4/MyD88/NF-κB signaling participates in the inflammatory response of the myocardium after CME, activating the NLRP3 inflammasome, promoting the inflammatory cascade, and aggravating myocardial injury. Blocking TLR4/MyD88/NF-κB signaling may help reduce myocardial injury and improve cardiac function after CME.

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Transcription Factor EB Alleviates Endothelial Cell Inflammation Through NLRP3 Inflammasome-Mediated Cell Pyroptosis in Atherosclerosis

10.21203/rs.3.rs-132711/v1 ◽

2020 ◽

Author(s):

Fengxia Guo ◽

Bing Hu ◽

Yanhua Sha ◽

Kangning Zhu ◽

Gang Li

Keyword(s):

Transcription Factor ◽

Endothelial Cell ◽

Inflammatory Response ◽

Nlrp3 Inflammasome ◽

Receptor Protein ◽

Enzyme Linked Immunosorbent Assay ◽

Inflammasome Activation ◽

Nlrp3 Inflammasome Activation ◽

Transcription Factor Eb ◽

Amp Activated Protein Kinase

Abstract BackgroundIncreasing evidence suggests that transcription factor EB (TFEB) inhibits inflammation in endothelial cell (ECs) and reduces development of atherosclerosis. However, little is known about the mechanism of action of TFEB on inflammation in atherosclerosis (AS).MethodsThe levels of TFEB, NLRP3, VCAM-1, ICAM-1, E-selectin, MCP-1, cleaved caspase-1, IL-1β and IL-18 in ECs were examined by immunoblotting, quantitative real time-polymerase chain reaction (qRT-PCR) , Enzyme-linked immunosorbent assay. The LDH activity were examined by LDH assay. TUNEL-positive cell were examined by TUNEL assay. The relationship between TFEB and NLRP3 were examined by immunofluorescence and coimmunoprecipitation. The effects of TFEB on atherosclerotic lesions by hematoxylin and eosin, TUNEL and collagen staining in the aortic valve of ApoE-/- mice fed a high fat diet (HFD).ResultsHere, we report that H2O2-induced cell pyroptosis and inflammatory response were mainly due to nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome activation. The nuclear protein TFEB was significantly increased by H2O2, and knockdown of TFEB aggravated cell pyroptosis and inflammatory response. TFEB directly bound to NLRP3 and blocked NLRP3-mediated cell pyroptosis and inflammatory response. The effect of H2O2 on TFEB might be associated with AMP-activated protein kinase/mechanistic target of rapamycin-dependent signaling pathways.ConclusionsOur findings indicated that a novel TFEB–NLRP3 axis was a critical regulator in EC pyroptosis and inflammation, which could be potential therapeutic targets in AS and related cardiovascular diseases.

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Role of ASM/Cer/TXNIP signaling module in the NLRP3 inflammasome activation

10.21203/rs.3.rs-68400/v2 ◽

2020 ◽

Author(s):

Jianjun Jiang ◽

Jin Yang ◽

Yining Shi ◽

Jiyu Cao ◽

Youjin Lu ◽

...

Keyword(s):

Nlrp3 Inflammasome ◽

Underlying Mechanism ◽

Acid Sphingomyelinase ◽

Receptor Protein ◽

Inflammasome Activation ◽

Mrna Levels ◽

Caspase 1 ◽

Nlrp3 Inflammasome Activation

Abstract Background: The NOD-Like Receptor Protein 3 (NLRP3) inflammasome is a crucial component of an array of inflammatory conditions. It functions by boosting the secretion of pro-inflammatory cytokines: interleukin-1β (IL-1β) and interleukin-18 (IL-18). Previous studies have established the vital role of the acid sphingomyelinase (ASM)/ceramide (Cer) pathway in the functional outcome of cells, with a particular emphasis on the inflammatory processes. This study aimed to explore the effects and associated underlying mechanism of Cer-induced NLRP3 inflammasome activation.Methods: Lipopolysaccharide (LPS)/adenosine triphosphate (ATP)-induced NLRP3 inflammasome activation in J774A.1 cells was used as an in vitro inflammatory model. Western blotting and Real-time PCR (RT-PCR) were used to detect the protein and mRNA levels, respectively. IL-1β and IL-18 levels were evaluated using ELISA kits. ASM assay kit and immunofluorescence were used to detect ASM activity and Cer content.Results: Imipramine, a well-known inhibitor of ASM, significantly inhibited ASM activity and inhibited Cer accumulation, which indicated ASM activation. Besides, it also suppressed the LPS/ATP-induced expression of proteins and mRNA: thioredoxin interacting protein (TXNIP), NLRP3, caspase-1, IL-1β and IL-18. Interestingly verapamil, a TXNIP inhibitor, suppressed LPS/ATP-induced TXNIP/NLRP3 inflammasome activation; however, it did not affect LPS/ATP-induced ASM activation and ceramide production. Further analysis showed that the exogenous C2-Cer treated J774A.1 cells induced the overexpression of TXNIP, NLRP3, caspase-1, IL-1β and IL-18. Besides, TXNIP siRNA or verapamil inhibited C2-Cer-induced TXNIP overexpression and NLRP3 inflammasome activation.Conclusion: This study demonstrated the involvement of the ASM/Cer/TXNIP signaling pathway in NLRP3 inflammasome activation.

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Annexin-A1 tripeptide attenuates surgery-induced neuroinflammation and memory deficits through regulation of the NLRP3 inflammasome

10.1101/2020.05.12.090654 ◽

2020 ◽

Author(s):

Zhiquan Zhang ◽

Qing Ma ◽

Ravikanth Velagapudi ◽

William E. Barclay ◽

Ramona M. Rodriguiz ◽

...

Keyword(s):

Nlrp3 Inflammasome ◽

Morphological Changes ◽

Memory Deficits ◽

Inflammasome Activation ◽

Surgical Trauma ◽

Annexin A1 ◽

Neuroprotective Effects ◽

Nlrp3 Inflammasome Activation ◽

The Impact

AbstractNeuroinflammation is a growing hallmark of perioperative neurocognitive disorders (PNDs), including delirium and longer-lasting cognitive deficits. We have developed a clinically-relevant orthopedic mouse model to study the impact of a common surgical procedure on the vulnerable brain. The mechanism underlying PNDs remain unknown. Here we evaluated the impact of surgical trauma on the NLRP3 inflammasome signaling, including the expression of apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, and IL-1β in the hippocampus of C57BL6/J male mice, adult (3-months) and aged (>18-months). Surgery triggered ASC specks formation in CA1 hippocampal microglia, but without inducing significant morphological changes in NLRP3 and ASC knockout mice. Since no therapies are currently available to treat PNDs, we assessed the neuroprotective effects of a biomimetic peptide derived from the endogenous inflammation-ending molecule, Annexin-A1 (ANXA1). We tested the hypothesis that this peptide (ANXA1sp) inhibits NLRP3 inflammasome activation, thus preventing microglial activation and hippocampal-dependent memory deficits. Together these results uncover a previously underrecognized role of the NLRP3 inflammasome in triggering postoperative neuroinflammation and offer a new target for advancing treatment of PNDs through resolution of inflammation.

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Insulin amyloid fibrils interact directly with the NLRP3, resulting in inflammasome activation and pyroptotic cell death

International Journal of Immunopathology and Pharmacology ◽

10.1177/20587384211038357 ◽

2021 ◽

Vol 35 ◽

pp. 205873842110383

Author(s):

Wakako Mori ◽

Naoe Kaneko ◽

Ayaka Nakanishi ◽

Tamotsu Zako ◽

Junya Masumoto

Keyword(s):

Cell Death ◽

Nlrp3 Inflammasome ◽

Amyloid Fibrils ◽

Mononuclear Cells ◽

Polyacrylamide Gel Electrophoresis ◽

Enzyme Linked Immunosorbent Assay ◽

Inflammasome Activation ◽

Amyloid Formation ◽

Molecular Pattern ◽

Nlrp3 Inflammasome Activation

Introduction Nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3), an intracellular pattern recognition receptor, recognizes various pathogen-associated molecular pattern and/or damage-associated molecular pattern molecules to constitute inflammasome that act as an interleukin (IL)-1β processing platform. Injected insulin is reported to induce focal amyloidosis and the formation of subcutaneous lumps called insulin balls, but the formation of subcutaneous lumps and the underlying cytotoxic mechanism has not been elucidated. Methods Amyloid formation was evaluated by thioflavin T spectroscopic assay and scanning electron microscopy. Binding between insulin amyloid fibrils and NLRP3 was evaluated by immunoprecipitation followed by native polyacrylamide gel electrophoresis. Inflammasome activation was evaluated by immunofluorescence speck formation called “ASC speck” and Western blotting. IL-1β secretion in culture supernatants of peripheral blood mononuclear cells was evaluated by enzyme-linked immunosorbent assay. Cytotoxicity was measured by lactate dehydrogenase release assay. Results Insulin amyloid fibrils interact directly with NLRP3, resulting in NLRP3 inflammasome activation and pyroptotic cell death. Conclusion Insulin ball formation and cytotoxicity may be associated with NLRP3 inflammasome activation followed by pyroptotic cell death.

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