Domain-like Receptor Family Pyrin Domain Research Articles

Trimethylamine oxide induces pyroptosis of vascular endothelial cells through ALDH2/ROS/NLRP3/GSDMD pathway.

Trimethylamine oxide (TMAO) is a metabolite of intestinal flora and is known to promote the progression of atherosclerotic plaques. However, how TMAO works, including its effect on vascular endothelial cells, is not fully understood. This study aims to explore the biological role of TMAO in human umbilical vein endothelial cells (HUVECs) and the underlying mechanism. Cell pyroptosis and the loss of plasma membrane integrity were induced under TMAO stimulation in HUVECs. The plasma membrane integrity of the cells was measured by Hoechst 33342/propidium iodide (PI) staining and lactate dehydrogenase leakage assay, and the changes in cell morphology were observed by atomic force microscope. The expression of proteins related to pyroptosis was determined by Western blotting or immunofluorescence. Mitochondrial acetaldehyde dehydrogenase 2 (ALDH2) activity in HUVECs was measured by the ALDH2 activity assay kit, and the level of reactive oxygen species (ROS) was detected by fluorescent probe DCFH-DA. TMAO induced pyroptotic cell death, manifesting by the presence of propidium iodide-positive cells, the leakage of lactate dehydrogenase, the production of N-terminal gasdermin D (GSDMD-N), and the formation of plasma membrane pores. Moreover, TMAO induced elevated expression of inflammasome components, nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC), and caspase-1 in cells. TMAO significantly inhibited ALDH2 activity and increased intracellular ROS production. However, the activation of ALDH2 by pharmacological manipulation attenuated TMAO-induced inflammasome activation and GSDMD-N production. TMAO induces pyroptosis of vascular endothelial cells through the ALDH2/ROS/NLRP3/GSDMD signaling pathway, which may be a potential therapeutic target for improving the treatment of atherosclerosis.

Role of nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 6 in activation of inflammation in human umbilical vein endothelial cells stimulated by Porphyromonas gingivalis-an in vitro study

Background/purposePorphyromonas gingivalis (P. gingivalis) could induce the activation of vascular endothelial cells and promote the formation of atherosclerosis. Nucleotide-binding oligomerization domain-like receptor family pyrin domain containing (NLRP) 6 could recognize P. gingivalis, but its role in atherosclerosis was unknown. The purpose of this study is to investigate the role of NLRP6 in the activation of inflammation in human umbilical vein endothelial cells (HUVECs) stimulated by P. gingivalis. Materials and methodsThe expression level of NLRP6 in HUVECs with or without P. gingivalis-challenge was observed. Down-regulating the expression of NLRP6 in HUVECs, the expression levels of interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein (MCP)-1 were detected. Then, the HUVECs with NLRP6-overexpressed were stimulated by P. gingivalis, the levels of inflammatory cytokines above were examined and compared with those in HUVECs triggered by P. gingivalis only. To evaluate the effect of NLRP6 on bacterial immune escape, the NLRP6 was overexpressed, and the colonies of P. gingivalis that survived in HUVECs were calculated. ResultsNLRP6 was expressed in HUVECs and decreased after P. gingivalis stimulation. Downregulation of NLRP6 decreased the expression levels of IL-1β, IL-6, IL-8, TNF-α and MCP-1 in HUVECs. Those cytokines above in NLRP6-overexpressed HUVECs with P. gingivalis-stimulation significantly increased than in the cells with P. gingivalis-stimulation only. Furthermore, over-expression of NLRP6 decreased the colonies of P. gingivalis survival in HUVECs. ConclusionNLRP6 regulated the activation of inflammation in HUVECs triggered by P. gingivalis and played an important role in P. gingivalis survival in endothelial cells.

TRIM16 exerts protective function on myocardial ischemia/reperfusion injury through reducing pyroptosis and inflammation via NLRP3 signaling

Myocardial infarction is still a leading cause of morbidity and mortality worldwide, but its pathogenesis has not been fully understood. In the study, we attempted to explore the effects of E3 ligase tripartite motif 16 (TRIM16) on myocardial ischemia-reperfusion (MI/R) injury in vivo and in vitro, and the underlying mechanisms. We identified that TRIM16 was indeed a potent regulator during MI/R progression in murine models and surprisingly showed a negative correlation with the concentrations of cardiac pro-inflammatory cytokines. Adenoviral vectors encoding GFP or TRIM16 (Ad-TRIM16) were subjected to mice through direct injection into the left ventricular (LV). We found that Ad-TRIM16 significantly reduced the infarct size, and improved the cardiac function and structure compared with the Ad-GFP mice after MI/R operation. More studies indicated that TRIM16 over-expression strongly meliorated nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and associated inflammatory response in hearts of MI/R-induced mice, which were validated in hypoxia/reoxygenation (H/R)-exposed primary cardiomyocytes in vitro. In particular, MI/R operation led to cardiac pyroptosis by increasing the cleavage of Caspase-1 and Gasdermin D (GSDMD), while being considerably abrogated upon TRIM16 over-expression. Mechanistically, TRIM16 interacted with NLRP3 and promoted the K48-linked polyubiquitination of NLRP3, ultimately promoted its degradation. Together, we identified TRIM16 as a novel E3 ubiquitin ligase for NLRP3, which played an essential role in modulating its expression, and subsequently influenced inflammatory response and pyroptosis in MI/R murine model, confirming that TRIM16 may be a potential therapeutic target for myocardial infarction.

The NLRP3 inflammasome contributes to inflammation-induced morphological and metabolic alterations in skeletal muscle.

Systemic inflammation is associated with skeletal muscle atrophy and metabolic dysfunction. Although the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome contributes to cytokine production in immune cells, its role in skeletal muscle is poorly understood. Here, we studied the link between inflammation, NLRP3, muscle morphology, and metabolism in in vitro cultured C2C12 myotubes, independent of immune cell involvement. Differentiated C2C12 myotubes were treated with lipopolysaccharide (LPS; 0, 10, and 100-200ng/mL) to induce activation of the NLRP3 inflammasome with and without MCC950, a pharmacological inhibitor of NLRP3-induced IL-1β production. We assessed markers of the NLRP3 inflammasome, cell diameter, reactive oxygen species, and mitochondrial function. NLRP3 gene expression and protein concentrations increased in a time-dependent and dose-dependent manner. Intracellular IL-1β concentration significantly increased (P<0.0001), but significantly less with MCC950 (P=0.03), suggestive of moderate activation of the NLRP3 inflammasome in cultured myotubes upon LPS stimulation. LPS suppressed myotube growth after 24h (P=0.03), and myotubes remained smaller up to 72h (P=0.0009). Exposure of myotubes to IL-1β caused similar alterations in cell morphology, andMCC950 mitigated these LPS-induced differences in cell diameter. NLRP3 appeared to co-localize with mitochondria, more so upon exposure to LPS. Mitochondrial reactive oxygen species were higher after LPS (P=0.03), but not after addition of MCC950. Myotubes had higher glycolytic rates, and mitochondria were more fragmented upon LPS exposure, which was not altered by MCC950 supplementation. LPS-induced activation of the NLRP3 inflammasome in cultured myotubes contributes to morphological and metabolic alterations, likely due to its mitochondrial association.

Schisandra chinensis (Turcz.) Baill. Protects against DSS-induced colitis in mice: Involvement of TLR4/NF-κB/NLRP3 inflammasome pathway and gut microbiota

Ethnopharmacological relevancethe fruit of Schisandra chinensis (Turcz.) Baill. (SC) is an important traditional Chinese herbal medicine, which has been widely used in traditional Chinese medicine (TCM) for treating intestinal diseases. It is also traditionally used as health product and medicine in Russia and other countries. However, the effect of SC ethanol extract on anti-ulcerative colitis (UC) has not been systematically studied yet. Aim of the studyWe investigated the protective effects and underlying action mechanisms of SC extract (SCE) for UC treatment. Materials and methodsAn animal model of UC induced by dextran sulfate sodium (DSS) was established. After oral administration of SCE, the Disease Activity Index (DAI) was calculated, the length of colon measured, levels of proinflammatory factors determined, and histopathology carried out to assess the therapeutic efficacy of SCE on UC. The effects of SCE on the toll-like receptor 4/nuclear factor-kappa B/nucleotide-binding and oligomerization domain-like receptor family pyrin domain containing 3 inflammasome (TLR4/NF-κB/NLRP3 inflammasome) signaling pathway were evaluated by western blotting. High-throughput sequencing was done to reveal the effect of SCE on the change of the gut microbiota (GM) in mice with DSS-induced colitis. ResultsSCE significantly reduced the DAI score, restored colon-length shortening, and ameliorated colonic histopathologic injury in mice with DSS-induced colitis. SCE inhibited the inflammatory response by regulating the TLR4/NF-κB/NLRP3 inflammasome pathway in mice with UC. SCE also maintained gut barrier function by increasing the levels of zonula occludens (ZO)-1 and occludin. 16S rRNA sequencing showed that SCE could reverse the GM imbalance caused by UC. ConclusionsSCE can ameliorate DSS-induced colitis, and that its effects might be associated with suppression of the TLR4/NF-κB/NLRP3 inflammasome pathway and GM regulation, which may provide significant supports for the development of potential candidates for UC treatment.

Blockade of NLRP3/Caspase-1/IL-1β Regulated Th17/Treg Immune Imbalance and Attenuated the Neutrophilic Airway Inflammation in an Ovalbumin-Induced Murine Model of Asthma

Asthma is a heterogeneous inflammatory disorder of the airways, and multiple studies have addressed the vital role of the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3)/caspase-1/interleukin-1β (IL-1β) pathway in asthma, but its impact on ovalbumin- (OVA-) induced neutrophilic asthma remains unclear. Here, we explored this pathway's effect on airway inflammation in neutrophilic asthma to clarify whether blocking this signaling could alleviate asthmatic airway inflammation. Using an established OVA-induced neutrophilic asthma mouse model, we provided asthmatic mice with a highly selective NLRP3 inhibitor, MCC950, and a specific caspase-1 inhibitor, Ac-YVAD-cmk. Our results indicated that asthmatic mice exhibited increased airway hyperresponsiveness, neutrophil infiltration, and airway mucus hypersecretion, upregulated retinoid-related orphan receptor-γt (RORγt) mRNA expression, and downregulated fork head box p3 (Foxp3) mRNA expression, which was concurrent with NLRP3 inflammasome activation and upregulation of caspase-1, IL-1β, and IL-18 expression in lung. Treatment of NLRP3 inflammasome inhibitors significantly attenuated airway hyperresponsiveness, airway inflammation, and reversed T helper 17 (Th17)/regulatory T (Treg) cell imbalance in asthmatic mice. We propose that the NLRP3/caspase-1/IL-1β pathway plays an important role in the pathological process of neutrophilic asthma and provides evidence that blocking this pathway could potentially be a treatment strategy to ameliorate airway inflammation in asthma after validation with future experimental and clinical studies.

AIP1 suppresses neovascularization by inhibiting the NOX4-induced NLRP3/NLRP6 imbalance in a murine corneal alkali burn model.

BackgroundApoptosis signal-regulating kinase 1-interacting protein 1 (AIP1) participates in inflammatory neovascularization induction. NADPH oxidase 4 (NOX4) produces reactive oxygen species (ROS), leading to an imbalance in nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) and NLR family pyrin domain containing 6 (NLRP6) expression. The mechanisms of AIP1, NOX4, ROS and inflammasomes in corneal neovascularization were studied herein.MethodsC57BL/6 and AIP1-knockout mice were used in this study. The alkali burn procedure was performed on the right eye. Adenovirus encoding AIP1 plus green fluorescence protein (GFP) (Ad-AIP1-GFP) or GFP alone was injected into the right anterior chamber, GLX351322 was applied as a NOX4 inhibitor, and then corneal neovascularization was scored. The expression of related genes was measured by quantitative real-time polymerase chain reaction, western blotting and immunofluorescence staining. 2′,7′-Dichlorofluorescin diacetate staining was used to determine the ROS levels.ResultsThe expression of AIP1 was decreased, while that of cleaved interleukin-1β (clv-IL-1β) and vascular endothelial growth factor A (VEGFa) was increased after alkali burn injury. NOX4 expression was increased, the imbalance in NLRP3/NLRP6 was exacerbated, and corneal neovascularization was increased significantly in AIP1-knockout mice compared with those in C57BL/6 mice after alkali burns. These effects were reversed by AIP1 overexpression. NLRP3/NLRP6 expression was imbalanced after alkali burns. GLX351322 reversed the imbalance in NLRP3/NLRP6 by reducing the ROS levels. This treatment also reduced the expression of clv-IL-1β and VEGFa, suppressing neovascularization.ConclusionsAIP1 and NOX4 can regulate corneal inflammation and neovascularization after alkali burn injury. Based on the pathogenesis of corneal neovascularization, these findings are expected to provide new therapeutic strategies for patients.Plain English summaryCorneal alkali burn injury is a common type of ocular injury that is difficult to treat in the clinic. The cornea is a clear and avascular tissue. Corneal neovascularization after alkali burn injury is a serious complication; it not only seriously affects the patient’s vision but also is the main reason for failed corneal transplantation. Corneal neovascularization affects approximately 1.4 million patients a year. We show for the first time that AIP1 and NOX4 can regulate corneal inflammation and neovascularization after alkali burns. The expression of AIP1 was decreased, while that of clv-IL-1β and VEGFa was increased after alkali burns. We tried to elucidate the specific molecular mechanisms by which AIP1 regulates corneal neovascularization. NOX4 activation was due to decreased AIP1 expression in murine corneas with alkali burns. NOX4 expression was increased, the imbalance in NLRP3/NLRP6 was exacerbated, and corneal neovascularization was increased significantly in AIP1-knockout mice compared with those in C57BL/6 mice after alkali burns. These effects were reversed by AIP1 overexpression. Additionally, NLRP3/NLRP6 expression was unbalanced, with NLRP3 activation and NLRP6 suppression in the corneal alkali burn murine model. Eye drops containing GLX351322, a NOX4 inhibitor, reversed the imbalance in NLRP3/NLRP6 by reducing ROS expression. This treatment also reduced the expression of clv-IL-1β and VEGFa, reducing neovascularization. Therefore, we provide new gene therapeutic strategies for patients. With the development of neovascularization therapy, we believe that in addition to corneal transplantation, new drug or gene therapies can achieve better results. Video Supplementary InformationThe online version contains supplementary material available at 10.1186/s12964-022-00877-5.

Prevention of the foreign body response to implantable medical devices by inflammasome inhibition.

SignificanceImplantable electronic medical devices (IEMDs) are used for some clinical applications, representing an exciting prospect for the transformative treatment of intractable conditions such Parkinson's disease, deafness, and paralysis. The use of IEMDs is limited at the moment because, over time, a foreign body reaction (FBR) develops at the device-neural interface such that ultimately the IEMD fails and needs to be removed. Here, we show that macrophage nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activity drives the FBR in a nerve injury model yet integration of an NLRP3 inhibitor into the device prevents FBR while allowing full healing of damaged neural tissue to occur.

Intestinal Candida albicans Promotes Hepatocarcinogenesis by Up-Regulating NLRP6.

Hepatocellular carcinoma (HCC), a primary liver cancer, is closely associated with the gut microbiota. However, the role of gut fungi in the development of HCC remains unclear. The aim of this study was to explore the influence of intestinal Candida albicans on HCC. Here, We found that patients with HCC showed significantly decreased diversity of the gut mycobiome and increased abundance of C. albicans, compared to the patients with liver cirrhosis. The gavage of C. albicans in the WT models increased the tumor size and weight and influenced the plasma metabolome, which was indicated by alterations in 117 metabolites, such as L-carnitine and L-acetylcarnitine, and several KEGG enriched pathways, such as phenylalanine metabolism and citrate cycle. Moreover, the expression of nucleotide oligomerization domain-like receptor family pyrin domain containing 6 (NLRP6) in the intestinal tissues and primary intestinal epithelial cells of the WT mice interacted with C. albicans increased. Notably, the colonization of C. albicans had no effect on tumor growth in Nlrp6–/– mice. In conclusion, the abnormal colonization of C. albicans reprogrammed HCC metabolism and contributed to the progression of HCC dependent on NLRP6, which provided new targets for the treatment of HCC.

Identification of WT161 as a Potent Agent for the Treatment of Colitis by Targeting the Nucleotide-Binding Domain-Like Receptor Family Pyrin Domain Containing 3 Inflammasome.

Inflammatory bowel diseases (IBD), including Crohn’s disease and ulcerative colitis (UC), are chronic and recurrent intestinal inflammatory disorders. Numerous studies have revealed that the nucleotide-binding domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome plays a pivotal role in the pathogenesis of IBD, and inhibition of the NLRP3 inflammasome alleviates colitis in experimental animals. Our previous study showed that C646, an inhibitor of histone acetyltransferase p300, has a protective role in dextran sulfate sodium (DSS)-induced colitis by targeting the NLRP3 inflammasome, making us further study the inhibitors of histone deacetylases (HDACs) in the treatment of colitis. In this study, we have shown that WT161, an inhibitor of HDAC6, exerts a protective role in a colitis model, blocks NLRP3 inflammasome activation, disrupts ASC speck formation, and decreases the expression of NLRP3. This study uncovers a new inhibitor of the NLRP3 inflammasome and suggests its potential application in the treatment of active IBD.

MiR-212-3p attenuates neuroinflammation of rats with Alzheimer's disease via regulating the SP1/BACE1/NLRP3/Caspase-1 signaling pathway.

Alzheimer’s disease (AD) ranks as the leading cause of dementia. MicroRNA (miR)-212-3p has been identified to exert neuroprotective effects on brain disorders. The current study analyzed the protective role of miR-212-3p in AD rats through regulating the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3)/Caspase-1 signaling pathway. The AD rat model was established through injection of amyloid-β 1-42 (Aβ1-42), followed by the Morris water maze test. The morphology and functions of neurons were observed. Furthermore, miR-212-3p, NLRP3, cleaved Caspase-1, gasdermin D N-terminus, interleukin (IL)-1β, and IL-18 expressions were measured. H19-7 cells were treated with Aβ1-42 to establish the AD cell model, followed by an assessment of cell viability and pyroptosis. Downstream targets of miR-212-3p and specificity protein 1 (SP1), as well as beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), were predicted by databases and testified using dual-luciferase and chromatin immunoprecipitation assays. miR-212-3p was weakly expressed in AD rats. miR-212-3p overexpression was linked to improved learning and memory capacities of AD rats and reduced neuronal pyroptosis linked to neuroinflammation attenuation. In vitro, miR-212-3p improved viability and suppressed pyroptosis of neurons through inhibiting NLRP3/Caspase-1. Overall, miR-212-3p inhibited SP1 expression to block BACE1-induced activation of NLRP3/Caspase-1, thereby attenuating neuroinflammation of AD rats.

Involvement of Inflammasome Components in Kidney Disease.

Inflammasomes are multiprotein complexes with an important role in the innate immune response. Canonical activation of inflammasomes results in caspase-1 activation and maturation of cytokines interleukin-1β and -18. These cytokines can elicit their effects through receptor activation, both locally within a certain tissue and systemically. Animal models of kidney diseases have shown inflammasome involvement in inflammation, pyroptosis and fibrosis. In particular, the inflammasome component nucleotide-binding domain-like receptor family pyrin domain containing 3 (NLRP3) and related canonical mechanisms have been investigated. However, it has become increasingly clear that other inflammasome components are also of importance in kidney disease. Moreover, it is becoming obvious that the range of molecular interaction partners of inflammasome components in kidney diseases is wide. This review provides insights into these current areas of research, with special emphasis on the interaction of inflammasome components and redox signalling, endoplasmic reticulum stress, and mitochondrial function. We present our findings separately for acute kidney injury and chronic kidney disease. As we strictly divided the results into preclinical and clinical data, this review enables comparison of results from those complementary research specialities. However, it also reveals that knowledge gaps exist, especially in clinical acute kidney injury inflammasome research. Furthermore, patient comorbidities and treatments seem important drivers of inflammasome component alterations in human kidney disease.

Induction of multiple subroutines of regulated necrosis in murine macrophages by natural BH3-mimetic gossypol.

Macrophages are critical sentinel cells armed with multiple regulated necrosis pathways, including pyroptosis, apoptosis followed by secondary necrosis, and necroptosis, and are poised to undergo distinct form(s) of necrosis for tackling dangers of pathogenic infection or toxic exposure. The natural BH3-mimetic gossypol is a toxic phytochemical that can induce apoptosis and/or pyroptotic-like cell death, but what exact forms of regulated necrosis are induced remains largely unknown. Here we demonstrated that gossypol induces pyroptotic-like cell death in both unprimed and lipopolysaccharide-primed mouse bone marrow-derived macrophages (BMDMs), as evidenced by membrane swelling and ballooning accompanied by propidium iodide incorporation and lactic acid dehydrogenase release. Notably, gossypol simultaneously induces the activation of both pyroptotic and apoptotic (followed by secondary necrosis) pathways but only weakly activates the necroptosis pathway. Unexpectedly, gossypol-induced necrosis is independent of nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, as neither inhibitor for the NLRP3 pathway nor NLRP3 deficiency protects the macrophages from the necrosis. Furthermore, necrotic inhibitors or even pan-caspase inhibitor alone does not or only partly inhibit such necrosis. Instead, a combination of inhibitors composed of pan-caspase inhibitor IDN-6556, RIPK3 inhibitor GSK'872 and NADPH oxidase inhibitor GKT137831 not only markedly inhibits the necrosis, with all apoptotic and pyroptotic pathways being blocked, but also attenuates gossypol-induced peritonitis in mice. Lastly, the activation of the NLRP3 pathway and apoptotic caspase-3 appears to be independent of each other. Collectively, gossypol simultaneously induces the activation of multiple subroutines of regulated necrosis in macrophages depending on both apoptotic and inflammatory caspases.

PEG-PEI/siROCK2 inhibits Aβ42-induced microglial inflammation via NLRP3/caspase 1 pathway.

ObjectivesThere is an urgent need to develop therapeutic strategies to improve the treatment outcome of Alzheimer’s disease. The treatment strategy of gene therapy mediated by nanocarrier systems brings new hope for the treatment of Alzheimer’s disease. ROCK2 is involved in various pathological processes of Alzheimer’s disease and may be a potential target for the treatment of Alzheimer’s disease. Our previous study indicated that PEG-PEI/siROCK2 [polyethyleneglycol-polyethyleneimine deliver ROCK2-siRNA, (PPSR)] prevented Aβ42-induced neurotoxicity and showed a promising prospect for the treatment of Alzheimer’s disease. However, whether PPSR has an effect on the microglial inflammation in Alzheimer’s disease is still unclear.Materials and methods3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay was used to detect the cytotoxicity of PEG-PEI and PPSR in primary microglial cells. Real-time PCR and western blotting were used to assess the expression of ROCK2 and nucleotide oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3)/caspase 1 pathway in primary microglial cells. ELISA assay was used to measure the effect of PPSR on attenuating the lipopolysaccharide (LPS) + Aβ-induced increase in IL-1β.ResultsPEG-PEI concentration less than 20 μg/ml and the N/P (molar ratio of PEG-PEI amino/siRNA phosphate) ratio of PPSR less than 50 showed no significant cytotoxicity in primary microglia cells. PPSR could effectively inhibit the expression of ROCK2 in primary microglial cells. A further study revealed that PPSR attenuates the LPS+Aβ-induced increase in IL-1β without affecting cell viability. In addition, we found that PPSR suppressed the Aβ-induced NLRP3/caspase 1 pathway in primary microglial cells.ConclusionPPSR inhibits Aβ42-induced microglial inflammation via NLRP3/caspase 1 pathway.

NLRP3 Inflammasome as a Common Denominator of Atherosclerosis and Abdominal Aortic Aneurysm.

Atherosclerosis and abdominal aortic aneurysm (AAA) are multifactorial diseases characterized by inflammatory cell infiltration, matrix degradation, and thrombosis in the arterial wall. Although there are some differences between atherosclerosis and AAA, inflammation is a prominent common feature of these disorders. The nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is a cytosolic multiprotein complex that activates caspase-1 and regulates the release of proinflammatory cytokines interleukin (IL)-1β and IL-18, as well as the induction of lytic cell death, termed pyroptosis, thereby leading to inflammation. Previous experimental and clinical studies have demonstrated that inflammation in atherosclerosis and AAA is mediated primarily through the NLRP3 inflammasome. Furthermore, recent results of the Canakinumab Anti-inflammatory Thrombosis and Outcome Study (CANTOS) showed that IL-1β inhibition reduces systemic inflammation and prevents atherothrombotic events; this supports the concept that the NLRP3 inflammasome is a promising therapeutic target for cardiovascular diseases, including atherosclerosis and AAA. This review summarizes current knowledge with a focus on the role of the NLRP3 inflammasome in atherosclerosis and AAA, and discusses the prospects of NLRP3 inflammasome-targeted therapy.

Cochlear Immune Response in Presbyacusis: a Focus on Dysregulation of Macrophage Activity.

Age-related hearing loss, or presbyacusis, is a prominent chronic degenerative disorder that affects many older people. Based on presbyacusis pathology, the degeneration occurs in both sensory and non-sensory cells, along with changes in the cochlear microenvironment. The progression of age-related neurodegenerative diseases is associated with an altered microenvironment that reflects chronic inflammatory signaling. Under these conditions, resident and recruited immune cells, such as microglia/macrophages, have aberrant activity that contributes to chronic neuroinflammation and neural cell degeneration. Recently, researchers identified and characterized macrophages in human cochleae (including those from older donors). Along with the age-related changes in cochlear macrophages in animal models, these studies revealed that macrophages, an underappreciated group of immune cells, may play a critical role in maintaining the functional integrity of thecochlea. Although several studies deciphered the molecular mechanisms that regulate microglia/macrophage dysfunction in multiple neurodegenerative diseases, limited studies have assessed the mechanisms underlying macrophage dysfunction in aged cochleae. In this review, we highlight the age-related changes in cochlear macrophage activities in mouse and human temporal bones. We focus on how complement dysregulation and the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 inflammasome could affect macrophage activity in the aged peripheral auditory system. By understanding the molecular mechanisms that underlie these regulatory systems, we may uncover therapeutic strategies to treat presbyacusis and other forms of sensorineural hearing loss.

Exposure to DEHP induces testis toxicity and injury through the ROS/mTOR/NLRP3 signaling pathway in immature rats

As the most abundantly used phthalate derivative, di-(2-ethylhexyl) phthalate (DEHP) leads to reproductive disorders, especially in males. Testicular injury can be triggered when the testis is exposed to DEHP during the immature stage. However, the potential mechanism is largely unclear. In the present study, Sprague-Dawley rats were exposed to 0, 250 and 500 mg/kg/day DEHP from postnatal day (PND) 20 to PND 30. The spermatogonia cell line GC-1 and spermatocyte cell line GC-2 were exposed to different doses of monoethylhexyl phthalate (MEHP), a metabolite of DEHP. Testicular injury was observed. Oxidative stress was evaluated both in vivo and in vitro. Our results showed that after DEHP exposure, the testicular structure was damaged and spermatogenesis was disturbed. We also found that oxidative stress was increased, as indicated by the upregulation of the important factors in the antioxidant pathway. Furthermore, the expression of autophagy-related proteins was significantly downregulated. Autophagy inhibition led to activation of the pyroptosis pathway. Nucleotide-binding and oligomerisation (NOD) domain-like receptor (NLR) family pyrin domain (PYD)-containing 3 (NLRP3), Caspase-1 and cytokine interleukin-1β (IL-1β) were significantly upregulated. Additionally, an imbalance in self-renewal and differentiation was observed in germ cells after DEHP exposure, causing the cessation of germ cell development. In summary, these data suggest that DEHP exposure enhances oxidative stress, downregulates autophagy, induces NLRP3 inflammasome activation and subsequently triggers pyroptosis in vivo and in vitro, which provides novel insight into DEHP-related injury in immature testes in the context of pyroptosis.

Aluminum impairs cognitive function by activating DDX3X-NLRP3-mediated pyroptosis signaling pathway

IntroductionAluminum is a kind of chemical contaminants in food which can induce neurotoxicity. Aluminum exposure is closely related to neurodegenerative diseases (ND), in which neuroinflammation might involve. However, the molecular mechanism of aluminum-induced neuroinflammation through pyroptosis is not fully clarified yet. Material and methodsThe mice model of subacute exposure to aluminum chloride (AlCl3) was established. BV2 microglia cells was treated with AlCl3 in vitro. Resveratrol (Rsv) was adopted as intervention agent. ResultsOur results showed that aluminum induced cognitive impairment, destroying blood brain barrier (BBB), and causing nerve injury in mice. Meanwhile, aluminum could stimulate nucleotide oligomerization domain-like receptor family pyrin domain containing protein 3 (NLRP3) inflammasome assembly and activate caspase-1 (CASP1), inducing gasdermin D (GSDMD)-mediated pyroptosis signaling, releasing cytokines IL-1β and IL-18, further promoting the activation of glial cells to magnify neuroinflammatory response. Moreover, DEAD-box helicase 3 X-linked (DDX3X) and stress granule RasGAP SH3-domain-binding protein 1 (G3BP1) both participated in neuroinflammation induced by aluminum. When co-treated with Rsv, these injuries were alleviated to some extent. ConclusionAluminum exposure could induce nerve cell pyroptosis and neuroinflammation by DDX3X-NLRP3 inflammasome signaling pathway, which could be rescued via Rsv activating sirtuin 1 (SIRT1).

Nucleotide-binding Oligomerization Domain-like Receptor Family Pyrin Domain Containing 3 Inflammasome in Alzheimer's Disease

Alzheimer's disease(AD)is a chronic neurodegenerative disease whose cause remains unclear.The β-amyloid plaques in the brain are one of the major pathological features of AD.However,the drugs targeting extracellular β-amyloid plaques have failed to cure the disease.Innate immunity and neuroinflammation play a role in the pathogenesis and progression of AD.As the macrophages existing in the central nervous system,microglia are related with extracellular β-amyloid deposition,intracellular neurofibrillary tangle formation,and neuron injury.Accumulating evidence demonstrates that the activation of nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3(NLRP3)inflammasome in microglia plays a role in AD,suggesting new therapeutic target for AD in this signaling pathway.This article reviewed the studies about the activation and regulation of NLRP3 inflammasome in the pathogenesis and progression of AD as well as the development of AD therapies targeting this pathway,aiming to provide reference for further studies in this field.

Varicocele-Mediated Male Infertility: From the Perspective of Testicular Immunity and Inflammation.

BackgroundVaricocele (VC) is present in 35 - 40% of men with infertility. However, current surgical and antioxidant treatments are not completely effective. In addition to oxidative stress, it is likely that other factors such as testicular immune microenvironment disorder contribute to irreversible testicular. Evidence suggests that VC is associated with anti-sperm antibodies (ASAs), spermatogenesis and testosterone secretion abnormalities, and testicular cytokine production. Moreover, inhibition of inflammation can alleviate VC-mediated pathogenesis. The normal function of the testis depends on its immune tolerance mechanism. Testicular immune regulation is complex, and many infectious or non-infectious diseases may damage this precision system.ResultsThe testicular immune microenvironment is composed of common immune cells and other cells involved in testicular immunity. The former includes testicular macrophages, T cells, dendritic cells (DCs), and mast cells, whereas the latter include Leydig cells and Sertoli cells (SCs). In animal models and in patients with VC, most studies have revealed an abnormal increase in the levels of ASAs and pro-inflammatory cytokines such as interleukin (IL)-1 and tumor necrosis factor (TNF)-alpha in the seminal plasma, testicular tissue, and even peripheral blood. It is also involved in the activation of potential inflammatory pathways, such as the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing (NLRP)-3 pathway. Finally, the development of VC-mediated infertility (VMI) may be facilitated by abnormal permeability of proteins, such as claudin-11, that constitute the blood-testis barrier (BTB).ConclusionsThe testicular immune response, including the production of ASAs and inflammatory factors, activation of inflammatory pathways, and destruction of the BTB may be involved in the pathogenesis of VMI it is necessary to further explore how patient outcomes can be improved through immunotherapy.