NLRP3 Inflammasome Components Research Articles

NLRP3 inflammasome activation promotes liver inflammation and fibrosis in experimental biliary atresia.

Biliary atresia (BA) is characterized by a progressive fibroinflammatory cholangiopathy in early infants with unknown etiology. Although innate immune disorder is involved in its mechanism, role of NLRP3 inflammasome in BA remains largely undefined. To explore the role of NLRP3 inflammasome in BA. The expressions of NLRP3 inflammasome-related genes were determined in BA patients. Role of NLRP3 inflammasome was evaluated using MCC950 in experimental BA. Furthermore, gadolinium chloride, a macrophage scavenger, was applied to validate the inflammasome's cellular localization. Finally, the effects of NLRP3 inflammasome activation on liver fibrosis were explored in vivo and vitro in experimental BA. The components of NLRP3 inflammasome were up-regulated in BA patients. Inflammasome-related genes showed positively correlated with liver inflammation and fibrosis in BA patients. In experimental BA, inflammasome-related genes were up-regulated, and their expressions were inhibited by MCC950, which promoted mice growth, protected liver function, alleviated obstructive jaundice, inhibited liver inflammation, and reduced serum IL-1β level. NLRP3 inflammasome was expressed in macrophages, and macrophage elimination exerted the same protective roles as MCC950 did in BA. Additionally, NLRP3 inflammasome activation promoted liver fibrosis in experimental BA. NLRP3 inflammasome activation in macrophages promoted liver inflammation and fibrosis in experimental BA.

Inflammation in obsessive-compulsive disorder: A literature review and hypothesis-based potential of transcranial photobiomodulation.

Obsessive-compulsive disorder (OCD) is a disabling neuropsychiatric disorder that affects about 2%-3% of the global population. Despite the availability of several treatments, many patients with OCD do not respond adequately, highlighting the need for new therapeutic approaches. Recent studies have associated various inflammatory processes with the pathogenesis of OCD, including alterations in peripheral immune cells, alterations in cytokine levels, and neuroinflammation. These findings suggest that inflammation could be a promising target for intervention. Transcranial photobiomodulation (t-PBM) with near-infrared light is a noninvasive neuromodulation technique that has shown potential for several neuropsychiatric disorders. However, its efficacy in OCD remains to be fully explored. This study aimed to review the literature on inflammation in OCD, detailing associations with T-cell populations, monocytes, NLRP3 inflammasome components, microglial activation, and elevated proinflammatory cytokines such as TNF-α, CRP, IL-1β, and IL-6. We also examined the hypothesis-based potential of t-PBM in targeting these inflammatory pathways of OCD, focusing on mechanisms such as modulation of oxidative stress, regulation of immune cell function, reduction of proinflammatory cytokine levels, deactivation of neurotoxic microglia, and upregulation of BDNF gene expression. Our review suggests that t-PBM could be a promising, noninvasive intervention for OCD, with the potential to modulate underlying inflammatory processes. Future research should focus on randomized clinical trials to assess t-PBM's efficacy and optimal treatment parameters in OCD. Biomarker analyses and neuroimaging studies will be important in understanding the relationship between inflammatory modulation and OCD symptom improvement following t-PBM sessions.

Mitochondria-targeted reactive oxygen species blockor SS-31 blocks hepatic stellate cell activation and alleviates hepatic fibrosis by regulating NLRP3 inflammasomes.

This study aimed to elucidate the effect of mitochondria-targeted reactive oxygen species (ROS) blockor SS-31 on hepatic stellate cells (HSC) activation during liver fibrosis. TGF-β1 was employed to induce HSC activation, while MitoSOX Red was utilized to assess the presence of mitochondrial ROS. The mitochondrial membrane potential (MMP) was measured using the JC-1 probe, and the ATP level was determined using a specific kit. The proliferation of HSCs was assessed using CCK-8 and colony formation assays, whereas flow cytometry was employed to detect HSC apoptosis. Fibrotic markers (COL1A1 and α-SMA) and NLRP3 inflammasome components (NLRP3, caspase-1, and ASC) were analyzed via Western blotting. Liver fibrosis was induced in mice using CCl4, and subsequently, histopathological changes were observed through HE staining and Masson staining. In TGF-β1-activated HSCs, mitochondrial ROS expression increased, MMP and ATP content decreased, indicating mitochondrial damage. After TGF-β1 induction, HSC proliferation increased, apoptosis decreased, and COL1A1, α-SMA, and NLRP3 inflammasome protein expression increased. After SS-31 treatment, mitochondrial ROS expression decreased, MMP recovered, ATP level increased, HSC proliferation decreased, apoptosis increased, and the expressions of COL1A1, α-SMA, and NLRP3 inflammasome decreased. NLRP3 blockor MCC950 treatment blocked HSC activation. CCL4-induced liver fibrosis mice had inflammatory cell infiltration and significant collagen fiber deposition in the liver. After SS-31 treatment, liver inflammation and collagen deposition were significantly reduced. SS-31, as a mitochondria-targeted ROS blockor, can block HSC activation by regulating the NLRP3 inflammasome, thereby alleviating liver fibrosis.

HIV Infection Drives Foam Cell Formation via NLRP3 Inflammasome Activation.

Persistent immune activation is linked to an increased risk of cardiovascular disease (CVD) in people with HIV (PWH) on antiretroviral therapy (ART). The NLRP3 inflammasome may contribute to elevated CVD risk in PWH. This study utilized peripheral blood mononuclear cells (PBMCs) from 25 PWH and 25 HIV-negative controls, as well as HIV in vitro infections. Transcriptional changes were analyzed using RNAseq and pathway analysis. Our results showed that in vitro HIV infection of macrophages and PBMCs from PWH had increased foam cell formation and expression of the NLRP3 inflammasome components and downstream cytokines (caspase-1, IL-1β, and IL-18), which was reduced with inhibition of NLRP3 activity using MCC950. Transcriptomic analysis revealed an increased expression of multiple genes involved in lipid metabolism, cholesterol storage, coronary microcirculation disorders, ischemic events, and monocyte/macrophage differentiation and function with HIV infection and oxLDL treatment. HIV infection and NLRP3 activation increased foam cell formation and expression of proinflammatory cytokines, providing insights into the mechanisms underlying HIV-associated atherogenesis. This study suggests that HIV itself may contribute to increased CVD risk in PWH. Understanding the involvement of the inflammasome pathway in HIV atherosclerosis can help identify potential therapeutic targets to mitigate cardiovascular risks in PWH.

NLRP3 Contributes to Sarcopenia Associated to Dependency Recapitulating Inflammatory-Associated Muscle Degeneration.

Sarcopenia, a complex and debilitating condition characterized by progressive deterioration of skeletal muscle, is the primary cause of age-associated disability and significantly impacts healthspan in elderly patients. Despite its prevalence among the aging population, the underlying molecular mechanisms are still under investigation. The NLRP3 inflammasome is crucial in the innate immune response and has a significant impact on diseases related to inflammation and aging. Here, we investigated the expression of the NLRP3 inflammasome pathway and pro-inflammatory cytokines in skeletal muscle and peripheral blood of dependent and independent patients who underwent hip surgery. Patients were categorized into independent and dependent individuals based on their Barthel Index. The expression of NLRP3 inflammasome components was significantly upregulated in sarcopenic muscle from dependent patients, accompanied by higher levels of Caspase-1, IL-1β and IL-6. Among older dependent individuals with sarcopenia, there was a significant increase in the MYH3/MYH2 ratio, indicating a transcriptional shift in expression from mature to developmental myosin isoforms. Creatine kinase levels and senescence markers were also higher in dependent patients, altogether resembling dystrophic diseases and indicating muscle degeneration. In summary, we present evidence for the involvement of the NLRP3/ASC/NEK7/Caspase-1 inflammasome pathway with activation of pro-inflammatory SASP in the outcome of sarcopenia in the elderly.

Anastrozole Protects against Human Coronavirus Infection by Ameliorating the Reactive Oxygen Species-Mediated Inflammatory Response.

The common human coronavirus (HCoV) exhibits mild disease with upper respiratory infection and common cold symptoms. HCoV-OC43, one of the HCoVs, can be used to screen drug candidates against SARS-CoV-2. We determined the antiviral effects of FDA/EMA-approved drug anastrozole (AZ) on two human coronaviruses, HCoV-OC43 and HCoV-229E, using MRC-5 cells in vitro. The AZ exhibited antiviral effects against HCoV-OC43 and HCoV-229E infection. Subsequent studies focused on HCoV-OC43, which is related to the SARS-CoV-2 family. AZ exhibited anti-viral effects and reduced the secretion of inflammatory cytokines, TNF-α, IL-6, and IL-1β. It also inhibited NF-κB translocation to effectively suppress the inflammatory response. AZ reduced intracellular calcium and reactive oxygen species (ROS) levels, including mitochondrial ROS and Ca2+, induced by the virus. AZ inhibited the expression of NLRP3 inflammasome components and cleaved IL-1β, suggesting that it blocks NLRP3 inflammasome activation in HCoV-OC43-infected cells. Moreover, AZ enhanced cell viability and reduced the expression of cleaved gasdermin D (GSDMD), a marker of pyroptosis. Overall, we demonstrated that AZ exhibits antiviral activity against HCoV-OC43 and HCoV-229E. We specifically focused on its efficacy against HCoV-OC43 and showed its potential to reduce inflammation, inhibit NLRP3 inflammasome activation, mitigate mitochondrial dysfunction, and suppress pyroptosis in infected cells.

Microglia TREM1-mediated neuroinflammation contributes to central sensitization via the NF-κB pathway in a chronic migraine model

BackgroundNeuroinflammation, mediated by the activation of microglia, contributes to central sensitization, which is associated with the development of chronic migraine (CM). TREM1 receptors amplify the inflammatory response. However, their relationship to CM is unclear. Thus, this study endeavoured to elucidate the exact role of TREM1 in CM.MethodsNitroglycerin (NTG) was repeatedly administered intraperitoneally to establish the CM model. Mechanical and thermal sensitivities were assessed using von Frey filaments and hot plate assays. Using Western blotting, TREM1, NF-κB pathway, NLRP3 inflammasome components, and proinflammatory cytokines were all detected. Immunofluorescence was used to examine the cellular distribution of TREM1 and NLRP3, the number of microglia, immunoreactivity, and morphological changes. We examined the effects of TREM1 antagonists (LR12) and NF-κB inhibitors (PDTC) on pain behaviour, as well as the production of c-fos and CGRP. Additionally, we investigated whether LR12 and PDTC affect the activation of microglia and the NLRP3 inflammasome. We synthesized siRNA and TREM1-overexpressing plasmids to transfect BV2 cells treated with LPS and normal BV2 cells and treated TREM1-overexpressing BV2 cells with PDTC. The NF-κB pathway, NLRP3 inflammasome components, and proinflammatory cytokines were quantified using Western blotting.ResultsFollowing NTG administration, the expression of TREM1 was significantly upregulated and exclusively localized in microglia in the TNC, and was well co-localized with NLRP3. Furthermore, activation of the classical NF-κB pathway was observed. Pre-treatment with LR12 and PDTC effectively attenuated mechanical hypersensitivity, suppressed the expression of c-fos and CGRP, and inhibited NF-κB activity in CM mice. Additionally, inhibition of TREM1 and NF-κB activity mitigated NTG-induced microglia and NLRP3 activation, as well as proinflammatory cytokines production. In vitro, knockdown of TREM1 resulted in attenuated activation of the NF-κB pathway following lipopolysaccharide (LPS) treatment and reduced expression of NLRP3 inflammasome components as well as proinflammatory cytokines. After TREM1 overexpression, the NF-κB pathway was activated, NLRP3 inflammasome components and proinflammatory cytokines were upregulated, and PDTC reversed this phenomenon.ConclusionsOur findings suggest that TREM1 regulates microglia and NLRP3 activation via the NF-κB pathway, thereby contributing to central sensitization and implicating its involvement in chronic migraine pathogenesis.

Dioscin Alleviates Periodontitis by Inhibiting NLRP3 Inflammasome Activation via Regulation of K+ Homeostasis and Mitochondrial Function.

Gingival inflammation and alveolar bone loss are characteristic manifestations of periodontitis. Interleukin (IL)-1β, the maturation of which is mainly regulated by NOD-like receptor protein (NLRP) 3 inflammasome, not only amplifies the inflammatory response but also triggers osteoclastogenesis, thereby accelerating the progression of periodontitis. Dioscin, a natural steroid saponin, has been shown to inhibit NLRP3 inflammasome. Nevertheless, research on the effectiveness of Dioscin for the management of periodontitis remains scarce. In this study, Dioscin was found to dramatically reduce the integral components of NLRP3 inflammasome, ultimately limiting IL-1β secretion. Notably, the inhibitory impact of Dioscin on NLRP3 inflammasome might be exerted by curbing the generation of mitochondrial (mt) reactive oxygen species (ROS) and oxidized (ox) mtDNA, which were mediated by inhibition of K+ efflux. Furthermore, Dioscin effectively alleviated periodontitis in mice. Overall, the results established that Dioscin could alleviate periodontitis by inhibiting NLRP3 inflammasome via modulation of the K+ efflux-mtROS-ox-mtDNA pathway, holding the potential to treat periodontitis and other NLRP3-driven inflammatory diseases.

IL-27 Alleviates Airway Inflammation and Airway Hyperresponsiveness in Asthmatic Mice by Targeting the CD39/ATP Axis of Dendritic Cells

Interleukin-27 receptor (IL-27R) is expressed in a variety of immune cells and structural cells, including dendritic cells. The mechanism of IL-27 in asthma has not been fully elucidated. This study aimed to examine whether IL-27 regulated the CD39/ATP axis of dendritic cells in asthma. Our results showed that in ovalbumin (OVA)-induced asthma mouse model, IL-27Rα−/− asthmatic mice showed increased airway resistance, increased infiltration of inflammatory cells in lung tissue, proliferation of goblet cells, enhanced expression of Muc5 AC around airway epithelium, increased total number of cells and eosinophils, increased levels of total IgE, OVA-IgE, IL-4, IL-5, IL-13 and IL-17 A, and increased expression of transcription factors GATA-3 and RORγt in lung tissue. The expression of CD39 mRNA and protein in the lung tissue of IL-27Rα−/− asthmatic mice decreased, and the expression of NLRP3, ASC and Caspase-1 in NLRP3 inflammasome components increased. The concentration of ATP was significantly increased compared with WT asthmatic mice. In vitro experiments showed that the expression of CD39 in lung dendritic cells of IL-27Rα−/− asthmatic mice decreased, while the expression of NLRP3 inflammasome components NLRP3, ASC and Caspase-1 increased. These findings indicate that IL-27 directly and indirectly regulates immunoinflammatory responses in asthma by acting on dendritic cells CD39/ATP Axis.

Berberine inhibits NLRP3 inflammasome activation by regulating mTOR/mtROS axis to alleviate diabetic cardiomyopathy

Diabetes cardiomyopathy (DCM) refers to myocardial dysfunction and disorganization resulting from diabetes. In this study, we investigated the effects of berberine on cardiac function in male db/db mice with metformin as a positive control. After treatment for 8 weeks, significant improvements in cardiac function and a reduction in collagen deposition were observed in db/db mice. Furthermore, inflammation and pyroptosis were seen to decrease in these mice, as evidenced by decreased expressions of p-mTOR, NOD-like receptor thermal protein domain associated protein 3 (NLRP3), IL-1β, IL-18, caspase-1, and gasdermin D (GSDMD). In vitro experiments on H9C2 cells showed that glucose exposure at 33 mmol/L induced pyroptosis, whereas berberine treatment reduced the expression of p-mTOR and NLRP3 inflammasome components. Moreover, berberine treatment was seen to inhibit the generation of mitochondrial reactive oxygen species (mtROS) and effectively improve cell damage in high glucose-induced H9C2 cells. The mTOR inhibitor, Torin-1, showed a therapeutic effect similar to that of berberine, by reducing the expression of NLRP3 inflammasome components and inhibiting mtROS generation. However, the activation of mTOR by MHY1485 partially nullified berberine's protective effects during high glucose stress. Collectively, our study reveals the mechanism that berberine regulates the mTOR/mtROS axis to inhibit pyroptosis induced by NLRP3 inflammasome activation, thereby alleviating DCM.

Investigating two pore potassium channel THIK‐1 expression in Alzheimer’s disease

AbstractBackgroundThe neuroinflammatory response, particularly the activation of the NLRP3 pathway, has been suggested as one of the key mechanisms of the pathological process in neurodegenerative diseases. Tandem pore domain halothane‐inhibited K+ channel 1 (THIK‐1) provides an upstream regulation of this neuroinflammatory response by modulating intracellular K+. While in vitro and in vivo model systems provide strong support for these mechanisms, unequivocal evidence from neurodegenerative disorders has been lacking.MethodThis research project investigated gene expression of markers in the THIK‐1/NLRP3 pathway by studying post‐mortem brain tissue of animal model representing Alzheimer’s disease (AD). In addition, THIK‐1 gene and protein expression in human post‐mortem brains of AD and Parkinson’s disease (PD) was investigated. Furthermore, DNA methylation of THIK‐1 gene in human post‐mortem brains of AD was analysed to explore a potential underlying mechanism of the changes of THIK‐1 gene expression.ResultA rat model of AD pathogenesis by intrahippocampal Aβ oligomer injection showed substantial up regulation of THIK‐1, glial activation markers, NLRP3 inflammasome components and IL‐1β. Changes in cortical gene expression for THIK‐1 support an inflammatory glial cell activation in both advanced AD and PD with dementia, not observed in the substantia nigra of the latter group. The increase in THIK‐1 expression was also supported by down‐regulation in DNA methylation of its corresponding gene in AD.ConclusionThe association between THIK‐1 expression and pathology changes observed in this study indicate a THIK‐1‐induced activation of this glial subtype in AD and PD. Therefore, specific blocks of the microglial THIK‐1 K+ channels at the early stage of AD and PD provides a potential therapeutic target.

HT-6184 Inhibits the Formation of the NLRP3 Inflammasome in Human Monocytic THP-1 Cells

Background The NLRP3 inflammasome is a multiprotein complex composed of several proteins, including NLRP3, ASC, Nek-7, and pro-caspase-1. Many immune cell populations express the NLRP3 inflammasome. In the presence of various exogenous stimuli such as lipopolysaccharide (LPS) or extracellular ATP, the NLRP3 inflammasome components assemble and become activated, releasing pro-inflammatory cytokines IL-1β and IL-18. One of the critical steps in inflammasome assembly is the recruitment of ASC and the formation of ASC protein aggregates called specks. These specks are large enough to be measured through microscopy, and the ASC speck count indicates NLRP3 activation. The release of IL-1β and IL-18 and the upregulation of NLRP3 inflammasome component genes have been observed in many inflammatory and hematological disorders, suggesting the NLRP3 pathway is involved in the disease pathogenesis of many diseases. Purpose HT-6184 is a small molecule that blocks the assembly of the NLRP3 inflammasome through allosteric binding to the protein Nek7. Here we demonstrate the ability of HT-6184 to modulate NLRP3 inflammasome formation by measuring ASC specks using a human monocytic THP-1 cell line engineered to express a GFP-labeled ASC protein. Methods THP1-ASC-GFP cells were cultured in RPMI 1640 with 10% heat-inactivated FBS, 100 μg/mL normocin, and 100 μg/mL Pen-Strep. Cells were seeded at 400,000 cells per well in a 96-well plate and left overnight. Cells were then treated with vehicle or LPS for 3 hours. Following LPS stimulation, cells were treated with vehicle or HT-6184 for 2 hours. After incubation, cells were treated with 5 μM Nigericin and imaged in 3-minute intervals for 1 hour. The images were analyzed for specks. Results By treating THP1-ASC-GFP with LPS and nigericin, we induced the formation of ASC specks and visualized them using fluorescent microscopy. Cells treated with 200 nM HT-6184 had significantly fewer ASC specks than the LPS and nigericin-treated control. ASC speck inhibition by HT-6184 was dose-dependent, as inhibition of speck formation decreased with lower doses of HT-6184. Conclusions HT-6184 effectively prevents the formation of ASC specks in THP-1-ASC-GFP cells. Since THP-1 cells are a monocytic cell line, this data suggests our ability to inhibit the NLRP3 pathway in hematological disorders effectively. By preventing inflammasome formation and activation, we expect to be able to reduce disease burden in hematological diseases.

Macrophage IL-1β-positive microvesicles exhibit thrombo-inflammatory properties and are detectable in patients with active juvenile idiopathic arthritis.

IL-1β is a leaderless cytokine with poorly known secretory mechanisms that is barely detectable in serum of patients, including those with an IL-1β-mediated disease such as systemic juvenile idiopathic arthritis (sJIA). Leukocyte microvesicles (MVs) may be a mechanism of IL-1β secretion. The first objective of our study was to characterize IL-1β-positive MVs obtained from macrophage cell culture supernatants and to investigate their biological functions in vitro and in vivo. The second objective was to detect circulating IL-1β-positive MVs in JIA patients. MVs were purified by serial centrifugations from PBMCs, or THP-1 differentiated into macrophages, then stimulated with LPS ± ATP. MV content was analyzed for the presence of IL-1β, NLRP3 inflammasome, caspase-1, P2X7 receptor, and tissue factor (TF) using ELISA, Western blot, or flow cytometry. MV biological properties were studied in vitro by measuring VCAM-1, ICAM-1, and E-selectin expression after HUVEC co-culture and factor-Xa generation test was realized. In vivo, MVs' ability to recruit leukocytes in a murine model of peritonitis was evaluated. Plasmatic IL-1β-positive MVs were studied ex vivo in 10 active JIA patients using flow cytometry. THP-1-derived macrophages stimulated with LPS and ATP released MVs, which contained NLRP3, caspase-1, and the 33-kDa precursor and 17-kDa mature forms of IL-1β and bioactive TF. IL-1β-positive MVs expressed P2X7 receptor and released soluble IL-1β in response to ATP stimulation in vitro. In mice, MVs induced a leukocyte peritoneal infiltrate, which was reduced by treatment with the IL-1 receptor antagonist. Finally, IL-1β-positive MVs were detectable in plasma from 10 active JIA patients. MVs shed from activated macrophages contain IL-1β, NLRP3 inflammasome components, and TF, and constitute thrombo-inflammatory vectors that can be detected in the plasma from active JIA patients.

Abstract 15963: A Novel SGK1 Inhibitor (SGK1-I), Prevents Obesity-Related Atrial Fibrillation

Introduction: Obesity is an important risk factor for atrial fibrillation. We have previously demonstrated the protective effect of genetic SGK1 inhibition in a mouse model of obesity-related atrial fibrillation (AF). SGK1-I is a novel and potent SGK1 inhibitor that has been shown to reduce late sodium current and has currently entered clinical trials as a potential treatment of long QT syndrome. Hypothesis: We sought to assess the efficacy of pharmacologic SGK1 inhibition in a mouse model of obesity-related AF. Methods: Wild type C57/Bl6 mice were fed a high fat diet containing 60% cholesterol (by calories) compounded with (HFD-SGK1i) or without (HFD) SGK1-I for 10 weeks. After feeding, the mice were assayed with invasive electrophysiology studies (EPS), optical mapping, and biochemical assays. Results: There were no significant differences in rate of weight gain, final body weight, fasting glucose, glucose tolerance, or tail-cuff blood pressure between the two groups of mice throughout the study. During EPS, there were no differences in nodal (sinus and atrio-ventricular) function or tissue (atrial/ventricular) refractory periods. However, HFD-SGK1i mice were significantly protected from obesity-related inducible AF during EPS, with a lower rate of AF inducibility (5.7% versus 1.5%, p<0.0001) and a lower total AF burden (35±54 versus 5.5±10.7 s, p=0.04). Optical mapping revealed abbreviated right (RA), but not left (LA), atrial action potential duration (APD) and attenuated inter-atrial APD differences in HFD-SGK1i mice as compared to HFD mice. In this context, Western blotting data demonstrated greater RA (versus LA) SGK1 activity/expression resulting from HFD, suggesting that SGK1 signaling may contribute to inter-atrial heterogeneity caused by HFD. Finally, protein expression of NLRP3 inflammasome components, Caspase-1 and ASC, as well as TGF-β expression were decreased in the SGK1-1 group; consistent with anti-inflammatory and anti-fibrotic signaling resulting from SGK1-I treatment. Conclusion: SGK1-I protects mice from obesity-related AF. These data further highlight SGK1 and its inhibition as a compelling target in cardiac arrhythmogenesis.

STING-Dependent Sensing of Self-DNA Driving Pyroptosis Contributes to Radiation-Induced Lung Injury

Radiation therapy (RT) is indispensable for managing thoracic carcinomas. However, its application is limited by radiation-induced lung injury (RILI), one of the most common and fatal complications of thoracic RT. Nonetheless, the exact molecular mechanisms of RILI remain poorly understood. To elucidate the underlying mechanisms, various knockout (KO) mouse strains were subjected to 16 Gy whole-thoracic RT. RILI was assessed by qRT-PCR, ELISA, histology, western blot, immunohistochemistry, and CT examination. To perform further mechanistic studies on the signaling cascade during the RILI process, pulldown, CHIP, and rescue assays were conducted. We found that the cGAS-STING pathway was significantly upregulated after irradiation exposure in both the mouse models and clinical lung tissues. Knocking down either cGAS or STING led to attenuated inflammation and fibrosis in mouse lung tissues. NLRP3 is hardwired to the upstream DNA-sensing cGAS-STING pathway to trigger of the inflammasome and amplification of the inflammatory response. STING deficiency suppressed the expressions of the NLRP3 inflammasome and pyroptosis-pertinent components containing IL-1β, IL-18, and cleaved caspase-1. Mechanistically, interferon regulatory factor 3, the essential transcription factor downstream of cGAS-STING, promoted the pyroptosis by transcriptionally activating NLRP3. Moreover, we found that RT triggered the release of self-dsDNA in the bronchoalveolar space, which is essential for the activation of cGAS-STING and the downstream NLRP3-mediated pyroptosis. Of note, Pulmozyme, an old drug for the management of cystic fibrosis, was revealed to have the potential to mitigate RILI by degrading extracellular dsDNA and then inhibiting the cGAS-STING-NLRP3 signaling pathway. These results delineated the crucial function of cGAS-STING as a key mediator of RILI, and described a mechanism of pyroptosis linking cGAS-STING activation with the amplification of initial RILI. These findings indicate that the dsDNA-cGAS-STING-NLRP3 axis might be potentially amenable to therapeutic targeting for RILI.

Leishmania braziliensis exosomes activate human macrophages to produce proinflammatory mediators.

Exosomes, organelles measuring 30-200nm, are secreted by various cell types. Leishmania exosomes consist of many proteins, including heat shock proteins, annexins, Glycoprotein 63, proteins exerting signaling activity and those containing mRNA and miRNA. Studies have demonstrated that Leishmania donovani exosomes downregulate IFN-γ and inhibit the expression of microbicidal molecules, such as TNF and nitric oxide, thus creating a microenvironment favoring parasite proliferation. Despite lacking immunological memory, data in the literature suggest that, following initial stimulation, mononuclear phagocytes may become "trained" to respond more effectively to subsequent stimuli. Here we characterized the effects of macrophage sensitization using L. braziliensis exosomes prior to infection by the same pathogen. Human macrophages were stimulated with L. braziliensis exosomes and then infected with L. braziliensis. Higher levels of IL-1β and IL-6 were detected in cultures sensitized prior to infection compared to unstimulated infected cells. Moreover, stimulation with L. braziliensis exosomes induced macrophage production of IL-1β, IL-6, IL-10 and TNF. Inhibition of exosome secretion by L. braziliensis prior to macrophage infection reduced cytokine production and produced lower infection rates than untreated infected cells. Exosome stimulation also induced the consumption/regulation of NLRP3 inflammasome components in macrophages, while the blockade of NLRP3 resulted in lower levels of IL-6 and IL-1β. Our results suggest that L. braziliensis exosomes stimulate macrophages, leading to an exacerbated inflammatory state that may be NLRP3-dependent.

Inflammasome activation in peritumoral astrocytes is a key player in breast cancer brain metastasis development

Inflammasomes, primarily responsible for the activation of IL-1β, have emerged as critical regulators of the tumor microenvironment. By using in vivo and in vitro brain metastasis models, as well as human samples to study the role of the NLRP3 inflammasome in triple-negative breast cancer (TNBC) brain metastases, we found NLRP3 inflammasome components and IL-1β to be highly and specifically expressed in peritumoral astrocytes. Soluble factors from TNBC cells induced upregulation and activation of NLRP3 and IL-1β in astrocytes, while astrocyte-derived mediators augmented the proliferation of metastatic cells. In addition, inhibition of NLRP3 inflammasome activity using MCC950 or dampening the downstream effect of IL-1β prevented the proliferation increase in cancer cells. In vivo, MCC950 reduced IL-1β expression in peritumoral astrocytes, as well as the levels of inflammasome components and active IL-1β. Most importantly, significantly retarded growth of brain metastatic tumors was observed in mice treated with MCC950. Overall, astrocytes contribute to TNBC progression in the brain through activation of the NLRP3 inflammasome and consequent IL-1β release. We conclude that pharmacological targeting of inflammasomes may become a novel strategy in controlling brain metastatic diseases.

Role of NLRP3 in the immunopathogenesis of neurodegenerative eye diseases

Neurodegenerative eye pathology is one of the leading causes of visual impairment and blindness worldwide. Primary open-angle glaucoma (POAG) belongs to the group of neurodegenerative ophthalmic diseases and is characterized by a permanent or periodic increase in intraocular pressure, followed by development of typical visual field defects, decreased visual acuity and optic nerve atrophy. Recent studies show that local inflammation, triggered by the innate immune system is the first line of defense against the pathogens and tissue destruction products, playing an important role in the POAG pathogenesis. The aim was to study the neurodegenerative ophthalmic disorder in a rabbit model, and to compare the data on distribution of alleles and genotypes of the polymorphic marker rs7525979 of NLRP3 gene in the patients with POAG. At the first stage, we studied the complex tissue samples of the retina/retinal pigment epithelium (TCS/RPE) isolated from the eyes of 14 experimental animals and 7 intact rabbits without eye damage. Neurodegenerative pathology of the eye in rabbits was carried out in the Experimental Center at the Helmholtz National Medical Research Center by a single subretinal injection of 0.01 ml of 0.9% sodium chloride solution. NLRP3 gene expression levels in TCS/RPE samples were evaluated by real-time polymerase chain reaction (PCR-RV). At the second stage, peripheral blood samples were examined in patients who were diagnosed with POAG of various stages, as well as without glaucoma. DNA was isolated from blood samples, which was subsequently analyzed for the polymorphic markers study using PCR-RT technique. According to the results of the study, we noted an increased expression of the NLRP3 gene in the TCS/RPE samples from experimental animals with simulated retinal degeneration. Moreover, an association of alleles and genotypes of the NLRP3 gene was revealed in patients with POAG. The data obtained may be indicative for involvement of NLRP3 inflammasome components in development of neurodegenerative retinal lesions in POAG.

Activation of NLRP3 Inflammasome in Liver of Long Evans Lactating Rats and Its Perinatal Effects in the Offspring after Bisphenol F Exposure.

The liver is the organ responsible for the metabolism and detoxification of BPF, the BPA analogue that is replacing it in plastic-based products. It is not known whether BPF can trigger inflammatory responses via the NLRP3 inflammasome, which plays a major role in the development of liver disease. The aim of this study was to evaluate nitrosative stress species (RNS) and NLRP3 inflammasome activation in the liver of lactating dams after BPF exposure. Moreover, it was studied whether this effect could also be observed in the liver of female and male offspring at postnatal day 6 (PND6). 36 Long Evans rats were randomly distributed according to oral treatment into three groups: Control, BPF-low dose (LBPF; 0.0365 mg/kg b.w./day) group and BPF-high dose (HBPF; 3.65 mg/kg b.w./day) group. The levels of nitrosative stress-inducing proteins (eNOS, iNOS, HO-1d), NLRP3 inflammasome components (NLRP3, PyCARD, CASP1) and proinflammatory cytokines (IL-1β, IL-18, IFN-γ and TNF-α) were measured by gene and protein expression in the liver of lactating dams and in female and male PND6 offspring. Lactating dams treated with LBPF showed a significant increase in iNOS and HO-1d, activation of NLRP3 components (NLRP3, PyCARD, CASP1) and promoted the release of proinflammatory cytokines such as IL-1β, IL-18, IFN-γ and TNF-α. Similar effects were found in female and male PND6 offspring after perinatal exposure. LBPF oral administration and perinatal exposure caused an increase of nitrosative stress markers and proinflammatory cytokines. Also, NLRP3 inflammasome activation was significantly increased in in the liver of lactating dams and PND6 offspring.

Abstract 126: Nlrp3 Chromatin Availability And Isolg-adducted Histones In Salt-sensitivity Of Blood Pressure

Salt-sensitivity of blood pressure puts both normotensive and hypertensive individuals at a higher risk for cardiovascular morbidity and mortality. Isolevuglandins (IsoLGs) are increased in multiple oxidative-stress associated diseases, including salt sensitive hypertension. Scavenging of IsoLGs using 2-HOBA in a mouse model of salt-sensitive hypertension blocked NLRP3 inflammasome in dendritic cells (DCs) and abolished salt-induced hypertensive response. IsoLGs adduct to histones, specifically H4. We tested the hypothesis that elevated sodium in antigen-presenting cells leads to IsoLG-adducted H4 histones and increased chromatin availability to NLRP3 inflammasome components contributing to salt-sensitive hypertension. In vivo studies were performed on 19 hypertensive subjects enrolled in an acute inpatient protocol to assess response to salt loading (460 mmoL/24 hrs) and salt depletion (10 mmoL/24 hrs, and furosemide 40 mg x 3). Isolated PBMCs from salt sensitive subject (δ;SBP SD-SL = -12.9) and a salt resistant subject (δ;SBP SD-SL = 0.35) were analyzed by ATACseq. In vitro studies were performed on isolated CD11c+ dendritic cells treated with either normal salt (150mM) or high salt (190mM) and histone protein extraction isolated for western blot and blotted for D11, an ScFv specific to IsoLG-adducted proteins. Additional in vitro studies were performed on isolated monocytes from 11 individuals treated with either normal or high salt and submitted for RNA sequencing. RNAseq data of isolated monocytes demonstrated an overall upregulation in differentially expressed histone modification genes after high salt visualized in a heatmap and PCA plot, specifically, upregulation of gene HIST4H4 encoding the Histone H4 (25.4 ± 4.6 vs 65.5 ± 6.5, [n=11, q=1.5 x 10 -3 ]). Changes in chromatin availability inflammasome component NLRP3 were more salt responsive in DCs of the salt-sensitive subject versus the salt-resistant subject after salt depletion. Additionally, high salt increased IsoLG-histone adduction in CD11c+ DCs. Our results suggest the high sodium environment increase in IsoLG-adducts may epigenetically regulate NLRP3 inflammasome components in SSBP.