Reducing NLRP3 Inflammasome Activation Research Articles

DDX3X coordinates host defense against influenza virus by activating the NLRP3 inflammasome and type I interferon response

Viruses and hosts have coevolved for millions of years, leading to the development of complex host–pathogen interactions. Influenza A virus (IAV) causes severe pulmonary pathology and is a recurrent threat to human health. Innate immune sensing of IAV triggers a complex chain of host responses. IAV has adapted to evade host defense mechanisms, and the host has coevolved to counteract these evasion strategies. However, the molecular mechanisms governing the balance between host defense and viral immune evasion is poorly understood. Here, we show that the host protein DEAD-box helicase 3 X-linked (DDX3X) is critical to orchestrate a multifaceted antiviral innate response during IAV infection, coordinating the activation of the nucleotide-binding oligomerization domain-like receptor with a pyrin domain 3 (NLRP3) inflammasome, assembly of stress granules, and type I interferon (IFN) responses. DDX3X activated the NLRP3 inflammasome in response to WT IAV, which carries the immune evasive nonstructural protein 1 (NS1). However, in the absence of NS1, DDX3X promoted the formation of stress granules that facilitated efficient activation of type I IFN signaling. Moreover, induction of DDX3X-containing stress granules by external stimuli after IAV infection led to increased type I IFN signaling, suggesting that NS1 actively inhibits stress granule–mediated host responses and DDX3X-mediated NLRP3 activation counteracts this action. Furthermore, the loss of DDX3X expression in myeloid cells caused severe pulmonary pathogenesis and morbidity in IAV-infected mice. Together, our findings show that DDX3X orchestrates alternate modes of innate host defense which are critical to fight against NS1-mediated immune evasion strategies during IAV infection.

Allicin alleviated acrylamide-induced NLRP3 inflammasome activation via oxidative stress and endoplasmic reticulum stress in Kupffer cells and SD rats liver

Acrylamide (AA) in heat-processed food leads to widespread concerns due to its hepatotoxicity. Allicin, a plant-derived antioxidant, possesses a significant protective effect on AA-induced hepatotoxicity, but the mechanism is still unclear. Herein, we investigated the mechanism in Kupffer cells and SD rats liver. Molecular docking, molecular dynamics simulation and LigPlus software speculated that allicin inhibited the activity of CYP2E1 expression by binding to its amino acid residues Phe116, Phe207, Leu210, Phe298, Ala299, Thr303, Val364 and Phe478 through hydrophobic interactions. Allicin decreased the reactive oxygen species (ROS) release and CYP2E1 protein expression and then alleviated the appearance of OS. Meanwhile, allicin significantly reduced ERS characteristic proteins GRP78, CHOP and UPR branch IRE1α pathway key proteins p-IRE, p-ASK, TRAF2 and XBP-1s expression. Simultaneously, allicin ameliorated OS and ERS activation, which inhibited the activation of the MAPK and NF-κB pathways, and down-regulated JNK, ERK, p38, p65 and IκBα phosphorylation. Allicin pre-treatment inhibited AA-induced inflammation as evidenced by reducing NLRP3 inflammasome activation, decreasing Cleaved-Caspase-1 expression as well as IL-1β, IL-18, IL-6 and TNF-α secretion. Taken together, our data provide new insights into possible signaling pathways involved in allicin attenuating AA-induced hepatotoxicity in vivo and in vitro.

Melatonin attenuates AFB1-induced cardiotoxicity via the NLRP3 signalling pathway.

ObjectiveThis study was conducted to investigate the protective effect of melatonin against aflatoxin B1 (AFB1) cardiotoxicity by evaluating NOD-like receptor family pyrin domain containing protein 3 (NLRP3) signalling.MethodsFour groups of five rats each were assessed: control group (vehicle only), two AFB1 (0.15 and 0.3 mg/kg)-treated groups, and a combined AFB1 (0.3 mg/kg) plus melatonin (5 mg/kg)-treated group. After 6 weeks of once-daily intragastric treatment, cardiac pathologic changes were observed under optical microscopy, and oxidative/antioxidative parameters were measured in myocardial homogenate. Cardiac tissue expression of NLRP3 and other important inflammasome components was also analysed.ResultsCompared with controls, increasing concentrations of AFB1 were associated with increased oxidative stress and caused myocardial structure damage. In addition, AFB1 dose-dependently activated the NLRP3 signalling pathway. All these indices were significantly ameliorated by combined AFB1 plus melatonin treatment versus high-dose AFB1 alone.ConclusionMelatonin may reduce NLRP3 inflammasome activation by inhibiting oxidative stress and thus protect against injury from AFB1-induced myocardial toxicity.

IL-6 promotes collagen-induced arthritis by activating the NLRP3 inflammasome through the cathepsin B/S100A9-mediated pathway

Rheumatoid arthritis (RA) is an inflammatory disease with symmetric polyarthritis. IL-6 and NLRP3 inflammasome in macrophages contribute to the pathogenesis of RA. This study aimed to investigate the relationship between IL-6 and the NLRP3 inflammasome in RA. Here, we found that IL-6 inhibition reduced NLRP3 inflammasome activation in mice with collage-induced arthritis (CIA). In vitro studies showed that IL-6 directly induced NLRP3 inflammasome activation via cathepsin B (CTSB) in the presence of ATP. In addition, S100A9 induced by ATP stimulation promoted the interaction of CTSB and NLRP3 to activate the NLRP3 inflammasome. Our findings show a novel mechanism of NLRP3 inflammasome activation by IL-6 that may lead to a potential therapy for RA by interrupting the interaction between IL-6 and the NLRP3 inflammasome.

Inhibition of miR-223 attenuates the NLRP3 inflammasome activation, fibrosis, and apoptosis in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is an independent and specific cardiomyopathy, which is associated with cardiac failure in diabetic patients. Currently, the pathogenesis of DCM is a popular research topic in the investigation of cardiovascular diseases. MicroRNAs (miRNAs) have been identified as the latent therapeutic targets for DCM. However, the functions and complex mechanisms of miRNAs in DCM have not been clarified. The cardiomyocyte injury model was established using high glucose (HG) ingestion, and the DCM rat model was established using 30 mg/kg streptozotocin. MicroRNA-223 (miR-223) expression was determined using qRT-PCR; the levels of NLRP3 inflammasome, fibrosis, and apoptosis-related genes and proteins were analyzed using qRT-PCR and western blot assays. Besides the morphological changes and fibrosis of myocardial tissues were evaluated using H&E and Masson staining. We discovered that miR-223 was highly expressed in the HG-induced cardiomyocyte injury model, and miR-223 inhibitor could further relieve the myocardial fibrosis and apoptosis, and inhibit NLRP3 inflammasome of HG-induced H9c2 cells. Additionally, we found that inhibition of miR-223 had obvious positive effects on the cardiac dysfunction and reduced the elevation of blood sugar in the DCM model rats. We found that the miRNA-223 inhibitor could improve the morphological structure and the degree of fibrosis in myocardial tissues in the DCM model rats. Moreover, we verified that inhibition of miR-223 could suppress the NLRP3 inflammasome activation, and alleviate myocardial fibrosis and apoptosis of the DCM model rats. In conclusion, our results suggested that miR-223 might be an underlying therapeutic target for DCM by reducing NLRP3 inflammasome activation, fibrosis, and apoptosis.

ADP/P2Y1 aggravates inflammatory bowel disease through ERK5-mediated NLRP3 inflammasome activation.

Inflammasomes are essential for inflammation and pathogen elimination in response to microbial infection and endogenous danger signals. However, the mechanism of inflammasome activation by endogenous danger signals mediated posttranslational modification and the connection between inflammasomes and inflammatory diseases remains elusive. In this study, we found that ADP was highly released from injured colonic tissue as a danger signal during inflammatory bowel disease. Consequently, extracellular ADP activated the NLRP3 inflammasome through P2Y1 receptor-mediated calcium signaling, which led to the maturation and secretion of IL-1β and further aggravation of experimental colitis. Genetic ablation or pharmacological blockade of the P2Y1 receptor significantly ameliorated DSS-induced colitis and endotoxic shock through reducing NLRP3 inflammasome activation. Moreover, ERK5-mediated tyrosine phosphorylation of ASC was essential for activation of the NLRP3 inflammasome. Thus, our study provides a novel theoretical basis for posttranslational modification of ASC in NLRP3 inflammasome activation and revealed that ADP/P2Y1 is a potential drug target for inflammatory bowel disease.

Induction of Autophagy by Pterostilbene Contributes to the Prevention of Renal Fibrosis via Attenuating NLRP3 Inflammasome Activation and Epithelial-Mesenchymal Transition.

Chronic kidney disease (CKD) is recognized as a global public health problem. NLRP3 inflammasome activation has been characterized to mediate diverse aspect mechanisms of CKD through regulation of proinflammatory cytokines, tubulointerstitial injury, glomerular diseases, renal inflammation, and fibrosis pathways. Autophagy is a characterized negative regulation mechanism in the regulation of the NLRP3 inflammasome, which is now recognized as the key regulator in the pathogenesis of inflammation and fibrosis in CKD. Thus, autophagy is undoubtedly an attractive target for developing new renal protective treatments of kidney disease via its potential effects in regulation of inflammasome. However, there is no clinical useful agent targeting the autophagy pathway for patients with renal diseases. Pterostilbene (PT, trans-3,5-dimethoxy-4-hydroxystilbene) is a natural analog of resveratrol that has various health benefits including autophagy inducing effects. Accordingly, we aim to investigate underlying mechanisms of preventive and therapeutic effects of PT by reducing NLRP3 inflammasome activation and fibrosis through autophagy-inducing effects. The renal protective effects of PT were evaluated by potassium oxonate (PO)-induced hyperuricemia and high adenine diet-induced CKD models. The autophagy induction mechanisms and anti-fibrosis effects of PT by down-regulation of NLRP3 inflammasome are investigated by using immortalized rat kidney proximal tubular epithelial NRK-52E cells. To determine the role of autophagy induction in the alleviating of NLRP3 inflammasome activation and epithelial-mesenchymal transition (EMT), NRK-52E with Atg5 knockdown [NRK-Atg5-(2)] cells were applied in the study. The results indicated that PT significantly reduces serum uric acid levels, liver xanthine oxidase activity, collagen accumulation, macrophage recruitment, and renal fibrosis in CKD models. At the molecular levels, pretreatment with PT downregulating TGF-β-triggered NLRP3 inflammasome activation, and subsequent EMT in NRK-52E cells. After blockage of autophagy by treatment of Atg5 shRNA, PT loss of its ability to prevent NLRP3 inflammasome activation and EMT. Taken together, we suggested the renal protective effects of PT in urate nephropathy and proved that PT induces autophagy leading to restraining TGF-β-mediated NLRP3 inflammasome activation and EMT. This study is also the first one to provide a clinical potential application of PT for a better management of CKD through its autophagy inducing effects.

SIRT1 agonism modulates cardiac NLRP3 inflammasome through pyruvate dehydrogenase during ischemia and reperfusion

Nucleotide-binding oligomerization domain-Like Receptor with a Pyrin domain 3 (NLRP3) inflammasome was emerged as a marker of metabolic dysregulation. We revealed that age-related Sirtuin-1 (SIRT1) modulates cardiac metabolism that medicated inflammatory response during ischemia and reperfusion (I/R) stress. We hypothesize that SIRT1 attenuates NLRP3 inflammasome-dependent inflammation and pyroptosis during myocardial I/R through metabolic modulation. C57BL/6J wild type (WT) mice, inducible cardiomyocyte specific SIRT1 knockout (icSIRT1 KO) and inducible cardiomyocyte specific PDH E1α knockout (icPDH E1α KO) mice were subjected to ligation and release of left anterior descending coronary artery for in vivo regional I/R models. The echocardiography measurement demonstrated that SIRT1 agonist SRT1720 (30 μg/g) improved cardiac systolic function during 45 min of ischemia and 6 h of reperfusion in C57BL/6J WT mice. The biochemical analysis showed that I/R triggered activation of cardiac pyruvate dehydrogenase (PDH), while SIRT1 agonist SRT1720 inhibited I/R-induced PDH activity and reduced production of reactive oxygen species (ROS) during myocardial I/R. Moreover, SRT1720 regulates PDH-related glucose oxidative metabolism to reduce NLRP3 inflammasome activation and pyroptosis in an Akt signaling dependent manner during I/R. Furthermore, an impaired Akt signaling was observed in icSIRT1 KO versus SIRT1fox/flox mice under I/R stress. Intriguingly, we observed lower levels of ROS generation, decreased NLRP3 levels and less pyroptosis occurred in the icPDH E1α KO versus PDH E1αflox/flox hearts during I/R. Taken together, the results indicate that SIRT1 agonism can inhibit activation of NLRP3 inflammasome via Akt-dependent metabolic regulation during ischemic insults by I/R.

Minocycline prevents neuronal hyperexcitability and neuroinflammation in medial prefrontal cortex, as well as memory impairment caused by repeated toluene inhalation in adolescent rats

Toluene can be intentionally misused by adolescents to experience psychoactive effects. Toluene has a complex mechanism of action and broad behavioral effects, among which memory impairment is reported consistently. We have previously reported that repeated toluene inhalation (8000 ppm) increases layer 5 prelimbic pyramidal cells' excitability in the medial prefrontal cortex (mPFC) of adolescent rats. Toluene also produces reactive oxygen species (ROS), which activate glial cells. Here, we tested the hypothesis that the anti-inflammatory agent minocycline would decrease toluene's effects because it inhibits NF-κB (nuclear factor enhancer of the kappa light chains of activated B cells) and reduces pro-inflammatory cytokine and ROS production. Our results show that minocycline (50 mg/kg, ip, for 10 days) prevents the hyperexcitability of mPFC neurons observed after repeated 8000 ppm toluene exposure (30 min/day, 2×/day for 10 days). Minocycline prevents toluene-induced hyperexcitability by a mechanism that averts the loss of the slow calcium-dependent potassium current, and normalizes mPFC neurons' firing frequency. These effects are accompanied by significant decreased expression of astrocytes and activated microglia in the mPFC, reduced NLRP3 inflammasome activation and mRNA expression levels of the pro-inflammatory cytokine interleukin 1β (IL-1β), as well as increased mRNA expression of the anti-inflammatory cytokine transforming growth factor β (TGF-β). Minocycline also prevents toluene-induced memory impairment in adolescent rats in the passive avoidance task and the temporal order memory test in which the mPFC plays a central role. These results show that neuroinflammation produces several effects of repeated toluene administration at high concentrations, and minocycline can significantly prevent them.

Scutellarin protects against myocardial ischemia-reperfusion injury by suppressing NLRP3 inflammasome activation

BackgroundActivation of NLRP3 inflammasome plays a key role in cardiac dysfunction for acute myocardial ischemia-reperfusion injury. Scutellarin (Scu) is a flavonoid purified from Erigeron breviscapus. Whether Scu has any influence on the activation of NLRP3 inflammasome in cardiomyocytes remains unknown. PurposeWe aimed to examine the therapeutic effect of Scu on cardiomyocyte ischemia-reperfusion (I/R) injury and its effect on NLRP3 inflammasome in rats with acute myocardial I/R injury and anoxia/reoxygenation (A/R)-induced H9c2 injuries. MethodsHeart injuries were induced through 30 min of ischemia followed by 24 h of reperfusion. Scu was intraperitoneally administered 15 min before vascular ligation. Effects of Scu on cardiac injury were detected by echocardiograms, TTC staining, and histological and immunohistochemical analyses. The effects of Scu on biochemical parameters were analyzed. H9c2 cells were pretreated with different concentrations of Scu for 6 h before A/R exposure. Afterward, cell viability, LDH release, and Hoechst 33342 and peromide iodine double staining were determined. Western blot analyses of proteins, including those involved in autophagy, NLRP3, mTOR complex 1 (mTORC1), and Akt signaling, were conducted. ResultsIn vivo study revealed that Scu improved diastolic dysfunction, ameliorated myocardium structure abnormality, inhibited myocyte apoptosis and inflammatory response, and promoted autophagy. Scu reduced NLRP3 inflammasome activation, inhibited mTORC1 activity, and increased Akt phosphorylation. In vitro investigation showed the same results. The Scu-mediated NLRP3 inflammasome and mTORC1 inhibition and cardioprotection were abolished through the genetic silencing of Akt by siRNA. ConclusionsThe cardioprotective effect of Scu was achieved through its anti-inflammatory effect. It suppressed the activation of NLRP3 inflammasome. In addition, inflammasome restriction by Scu was dependent on Akt activation and mTORC1 inhibition.

Rapamycin Attenuates High Glucose-Induced Inflammation Through Modulation of mTOR/NF-κB Pathways in Macrophages.

Background: The NLRP3 inflammasome is one of the key contributors to impaired wound healing in diabetes. In this study, we assessed the role of rapamycin on high glucose-induced inflammation in THP-1-derived macrophages and investigated the underlying signaling mechanisms.Methods: THP-1-derived macrophages were treated with high glucose to induce NLRP3 inflammasome activation. The cells were pretreated with rapamycin, BAY 11-7082, or PDTC before exposure to HG. mTOR, NF-κB, and NLRP3 inflammasome expression were measured by western blotting.Results: We found that rapamycin reduced NLRP3 inflammasome activation in macrophages. Rapamycin reduced NLRP3 inflammasome activation by inhibiting mTOR phosphorylation and NF-κB activation. Moreover, mTOR siRNA inhibited NF-κB activation, leading to the suppression of NLRP3 inflammasome activation.Conclusion: Rapamycin can ameliorate high glucose-induced NLRP3 inflammasome activation by attenuating the mTOR/NF-κB signaling pathway in macrophages. Rapamycin may act as a possible therapeutic option for high glucose-induced inflammatory response in impaired wound healing in the future.

Cilostazol ameliorates high free fatty acid (FFA)-induced activation of NLRP3 inflammasome in human vascular endothelial cells

Cardiovascular disease is recognized as a leading cause of death worldwide, but the risk of death is 2–3 times higher for individuals with diabetes. NLRP3 inflammasome activation is a leading pathway of vascular damage, and new treatment methods are needed to reduce NLRP3 inflammasome expression, along with a detailed understanding of how those treatments work. In a series of assays on human vascular endothelial cells that were exposed to high concentrations of free fatty acids (FFA) to induce a diabetes-like environment, we found a significant impact of cilostazol, a vasodilator widely used to treat blood flow problems and well-tolerated medication. To our knowledge, this study is the first to demonstrate the effects of cilostazol in primary human aortic endothelial cells. We found that cilostazol significantly reduced NLRP3 inflammasome activation, as well as the activity of other related and harmful factors, including oxidative stress, expression of NADPH oxidase 4 (NOX-4), thioredoxin-interacting protein (TxNIP), high mobility group box 1 (HMGB-1), interleukin 1β (IL-1β) and IL-18. Cilostazol also protected the functionality of sirtuin 1 (SIRT1), which serves to restrict NLRP3 inflammasome activity, when exposure to FFAs would have otherwise impaired its function. Thus, it appears that cilostazol’s mechanism of action in reducing NLRP3 inflammasome activation is an indirect one; it protects SIRT1, which then allows SIRT1 to perform its regulatory job. Cilostazol has potential as an already-available, well-tolerated preventive medication that may alleviate some of the adverse vascular effects of living with diabetes. The findings of the present study lay the groundwork for further research on the potential of cilostazol as a safe and effective treatment against diabetic endothelial dysfunction and vacular disease.

Drugs to Inhibit the NLRP3 Inflammasome: Not Always On Target.

Drugs to Inhibit the NLRP3 Inflammasome: Not Always On Target.

PINK1-parkin pathway of mitophagy protects against contrast-induced acute kidney injury via decreasing mitochondrial ROS and NLRP3 inflammasome activation

Contrast-induced acute kidney injury (CI-AKI) occurs in more than 30% of patients after intravenous iodinated contrast media and causes serious complications, including renal failure and mortality. Recent research has demonstrated that routine antioxidant and alkaline therapy failed to show benefits in CI-AKI patients with high risk for renal complications. Mitophagy is a mechanism of selective autophagy, which controls mitochondrial quality and mitochondrial reactive oxygen species (ROS) through degradation of damaged mitochondria. The role of mitophagy and its regulation of apoptosis in CI-AKI are poorly understood. In this study, we demonstrated that mitophagy was induced in renal tubular epithelial cells (RTECs) during CI-AKI, both in vivo and in vitro. Meanwhile, contrast media–induced mitophagy was abolished when silencing PINK1 or PARK2 (Parkin), indicating a dominant role of the PINK1-Parkin pathway in mitophagy. Moreover, mitochondrial damage, mitochondrial ROS, RTEC apoptosis, and renal injury under contrast exposure were more severe in PINK1- or PARK2-deficient cells and mice than in wild-type groups. Functionally, PINK1-Parkin–mediated mitophagy prevented RTEC apoptosis and tissue damage in CI-AKI through reducing mitochondrial ROS and subsequent NLRP3 inflammasome activation. These results demonstrated that PINK1-Parkin–mediated mitophagy played a protective role in CI-AKI by reducing NLRP3 inflammasome activation.

Curcumin attenuates murine lupus via inhibiting NLRP3 inflammasome

Despite rapid progress in the understanding of systemic lupus erythematosus (SLE), there is still an urgent need for novel and more effective interventions. Curcumin, a natural polyphenol compound, has been shown to be anti-inflammatory in various disorders. In this study, we investigated the potential therapeutic value of curcumin in SLE. Lupus-prone female MRL/lpr mice were treated with curcumin. The development and extent of nephritis were assessed by monitoring proteinuria and by histologic analysis. Serum anti-dsDNA levels were measured by enzyme-linked immunosorbent assay. Kidney samples were analyzed by Western blot. In vitro, mouse podocytes were used for investigation in the presence of mouse anti-dsDNA antibody-positive (anti-dsDNA+) serum. Curcumin treatment dramatically decreased proteinuria and renal inflammation. Serum anti-dsDNA levels and spleen size were also reduced by curcumin. In addition, curcumin reduced NLRP3 inflammasome activation in lupus-prone mice. In vitro, curcumin significantly inhibited anti-dsDNA+ serum induced expression of NLRP3 inflammasome in podocytes. Overall, these data demonstrate the potential use of curcumin in SLE treatment.

Abstract WP101: Progesterone Counteracts Stress-Induced Microglial Priming by Reducing NLRP3 Inflammasome Activation After Ischemic Injury

Introduction: Cerebral ischemia, a consequence of cardiac arrest and stroke, is a leading cause of death and disability in the U.S. To improve translational studies, STAIR recommends augmenting animal models with comorbidities that “better reproduce the pathophysiological state” of stroke patients. Therefore, we incorporated social stress into our ischemia model (Espinosa-Garcia et al., 2017). Prior exposure to social stress upregulates the inflammatory status of microglia. They become primed—sensitized to activation by subsequent ischemia—worsening outcome. Such potentiated activation may result from the release of danger signals in the brain, such as HMGB-1, which binds to TLR4 receptors and activates inflammasomes. The NLRP3 inflammasome consists of a sensor molecule, NLRP3, the ASC adaptor, and caspase-1, whose activation leads to pro-inflammatory IL-1β production. We hypothesized that progesterone (P4) administration will reduce NLRP3 inflammasome activation, one of the molecular mechanisms underlying P4’s neuroprotective effects against ischemia combined with stress. Methods: Adult male rats were exposed to social defeat stress for 8 days and then subjected to global ischemia. P4 was administered 2 and 6h after occlusion and then daily for 7 days. Animals were killed at 7 or 14 days post-ischemia and their hippocampi dissected for western blots. The hippocampus is highly sensitive to stress and selectively vulnerable to global ischemia. Results: Consistent with previous reports, stress primed microglia and increased ( p <0.05) HMGB1 and NLRP3 levels, with no changes in IL-1β production in non-ischemic controls. Stressed ischemic animals showed potentiated ( p <0.05) NLRP3 inflammasome activation and increased IL-1β production. P4 treatment robustly reduced ( p <0.05) HMGB1, TLR4, phospho-IκB, NLRP3, ASC, cleaved caspase-1, and IL-1β levels in both stressed and non-stressed ischemic animals. Conclusion: Our data show that P4 can modulate stress-induced microglial priming to subsequent ischemic injury by counteracting NLRP3 inflammasome activation in the hippocampus. P4 may thus prove a promising neuroprotective agent to reduce inflammation associated with poor outcome in stroke patients with comorbid stress.

The Potential Effect of Chinese Herbal Formula Hongqijiangzhi Fang in Improving NAFLD: Focusing on NLRP3 Inflammasome and Gut Microbiota.

The present study investigates the potential therapeutic mechanism underlying the effects of the Chinese herbal formula Hongqijiangzhi Fang (HJF) on nonalcoholic fatty liver disease (NAFLD) in rats. Male Sprague Dawley (SD) rats were randomly divided into 4 groups (n = 8): control group was fed a normal diet, three other groups were fed high-fat diets (HFD), and the two treatment groups were intragastrically given a compound probiotic or HJF during the molding time. After 16 w, related indices were detected. The results showed that HJF significantly reduced abdominal aorta serum cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), IL-1β, and IL-18, portal venous serum lipopolysaccharide (LPS), and liver TC and TG levels in HFD-fed rats. HJF ameliorated hepatic steatosis in the liver and improved the intestinal barrier in HFD-fed rats. Activation of the NLRP3 inflammasome was reduced by HJF in HFD-fed rats. Additionally, the abundances of A. muciniphila (Verrucomicrobiaceae), F. rappini (Helicobacteraceae), and Enterobacteriaceae bacteria significantly decreased in HJF-treated HFD-fed rats. In conclusion, these result suggested that the Chinese herbal formula HJF reduced hepatic steatosis maybe through decreasing certain gut bacteria (such as Enterobacteriaceae bacteria and F. rappini), alleviating intestinal endotoxemia and reducing NLRP3 inflammasome activation.

Low esterified pectin protects from type 1 diabetes by reducing NLRP3 inflammasome activation, maintaining intestinal barrier integrity and by maintaining prediabetic microbiota compositions in NOD mice

Low esterified pectin protects from type 1 diabetes by reducing NLRP3 inflammasome activation, maintaining intestinal barrier integrity and by maintaining prediabetic microbiota compositions in NOD mice

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

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.

IL-36 Signaling Facilitates Activation of the NLRP3 Inflammasome and IL-23/IL-17 Axis in Renal Inflammation and Fibrosis

IL-36 cytokines are proinflammatory and have an important role in innate and adaptive immunity, but the role of IL-36 signaling in renal tubulointerstitial lesions (TILs), a major prognostic feature of renal inflammation and fibrosis, remains undetermined. In this study, increased IL-36α expression detected in renal biopsy specimens and urine samples from patients with renal TILs correlated with renal function impairment. We confirmed the increased expression of IL-36α in the renal tubular epithelial cells of a mouse model of unilateral ureteral obstruction (UUO) and related cell models using mechanically induced pressure, oxidative stress, or high mobility group box 1. In contrast, the kidneys of IL-36 receptor (IL-36R) knockout mice exhibit attenuated TILs after UUO. Compared with UUO-treated wild-type mice, UUO-treated IL-36 knockout mice exhibited markedly reduced NLRP3 inflammasome activation and macrophage/T cell infiltration in the kidney and T cell activation in the renal draining lymph nodes. In vitro, recombinant IL-36α facilitated NLRP3 inflammasome activation in renal tubular epithelial cells, macrophages, and dendritic cells and enhanced dendritic cell-induced T cell proliferation and Th17 differentiation. Furthermore, deficiency of IL-23, which was diminished in IL-36R knockout UUO mice, also reduced renal TIL formation in UUO mice. In wild-type mice, administration of an IL-36R antagonist after UUO reproduced the results obtained in UUO-treated IL-36R knockout mice. We propose that IL-36 signaling contributes to the pathogenesis of renal TILs through the activation of the NLRP3 inflammasome and IL-23/IL-17 axis.