NLR Family Pyrin Domain Containing 3 Inflammasome Research Articles

Dasatinib suppresses particulate-induced pyroptosis and acute lung inflammation.

Background: Humans are constantly exposed to various industrial, environmental, and endogenous particulates that result in inflammatory diseases. After being engulfed by immune cells, viz. Macrophages, such particulates lead to phagolysosomal dysfunction, eventually inducing pyroptosis, a form of cell death accompanied by the release of inflammatory mediators, including members of the interleukin (IL)-1 family. Phagolysosomal dysfunction results in the activation of the nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, an immune complex that induces pyroptosis upon exposure to various external stimuli. However, several particulates induce pyroptosis even if the NLRP3 inflammasome is inhibited; this indicates that such inhibition is not always effective in treating diseases induced by particulates. Therefore, discovery of drugs suppressing particulate-induced NLRP3-independent pyroptosis is warranted. Methods: We screened compounds that inhibit silica particle (SP)-induced cell death and release of IL-1α using RAW264.7 cells, which are incapable of NLRP3 inflammasome formation. The candidates were tested for their ability to suppress particulate-induced pyroptosis and phagolysosomal dysfunction using mouse primary macrophages and alleviate SP-induced NLRP3-independent lung inflammation. Results: Several Src family kinase inhibitors, including dasatinib, effectively suppressed SP-induced cell death and IL-1α release. Furthermore, dasatinib suppressed pyroptosis induced by other particulates but did not suppress that induced by non-particulates, such as adenosine triphosphate. Dasatinib reduced SP-induced phagolysosomal dysfunction without affecting phagocytosis of SPs. Moreover, dasatinib treatment strongly suppressed the increase in IL-1α levels and neutrophil counts in the lungs after intratracheal SP administration. Conclusion: Dasatinib suppresses particulate-induced pyroptosis and can be used to treat relevant inflammatory diseases.

Membrane-bound Interleukin-1α mediates leukocyte adhesion during atherogenesis.

The interleukin-1 (IL-1) family and the NLR family pyrin domain-containing 3 (NLRP3) inflammasome contribute to atherogenesis but the underlying mechanisms are incompletely understood. Unlike IL-1β, IL-1α is not dependent on the NLRP3 inflammasome to exert its pro-inflammatory effects. Here, a non-genetic model was applied to characterize the role of IL-1α, IL-1β, and NLRP3 for the pathogenesis of atherosclerosis. Atherogenesis was induced by gain-of-function PCSK9-AAV8 mutant viruses and feeding of a high-fat western diet (WTD) for 12 weeks in C57Bl6/J wildtype mice (WT) and in Il1a-/-, Nlrp3-/-, and Il1b-/- mice. PCSK9-Il1a-/- mice showed reduced atherosclerotic plaque area in the aortic root with lower lipid accumulation, while no difference was observed between PCSK9-WT, PCSK9-Nlrp3-/- and PCSK9-Il1b-/- mice. Serum proteomic analysis showed a reduction of pro-inflammatory cytokines (e.g., IL-1β, IL-6) in PCSK9-Il1a-/- as well as in PCSK9-Nlrp3-/- and PCSK9-Il1b-/- mice. Bone marrow dendritic cells (BMDC) of PCSK9-WT, PCSK9-Nlrp3-/-, and PCSK9-Il1b-/- mice and primary human monocytes showed translocation of IL-1α to the plasma membrane (csIL-1α) upon stimulation with LPS. The translocation of IL-1α to the cell surface was regulated by myristoylation and increased in mice with hypercholesterolemia. CsIL-1α and IL1R1 protein-protein interaction on endothelial cells induced VCAM1 expression and monocyte adhesion, which was abrogated by the administration of neutralizing antibodies against IL-1α and IL1R1. The results highlight the importance of IL-1α on the cell surface of circulating leucocytes for the development of atherosclerosis. PCSK9-Il1a-/- mice, but not PCSK9-Nlrp3-/- or PCSK9-Il1b-/- mice, are protected from atherosclerosis after induction of hypercholesterolemia independent of circulating cytokines. Myristoylation and translocation of IL-1α to the cell surface in myeloid cells facilitates leukocyte adhesion and contributes to the development of atherosclerosis.

Mefloquine targets NLRP3 to reduce lipopolysaccharide-induced systemic inflammation and neural injury.

The NLR family pyrin domain containing 3 (NLRP3) inflammasome plays an important role in the pathogenesis of a wide variety of human diseases. So far, drugs directly and specifically targeting the NLRP3 inflammasome are not available for clinical use since the safety and efficacy of new compounds are often unclear. A promising approach is thus to identify NLRP3 inhibitors from existing drugs that are already in clinical use. Here, we show that mefloquine, a well-known antimalarial drug, is a highly selective and potent NLRP3 inhibitor by screening a FDA-approved drug library. Mechanistically, mefloquine directly binds to the NLRP3 NACHT and LRR domains to prevent NLRP3 inflammasome activation. More importantly, mefloquine treatment attenuates the symptoms of lipopolysaccharide-induced systemic inflammation and Parkinson's disease-like neural damage in mice. Our findings identify mefloquine as a potential therapeutic agent for NLRP3-driven diseases and migth expand its clinical use considerably.

Allicin protects against LPS-induced cardiomyocyte injury by activating Nrf2-HO-1 and inhibiting NLRP3 pathways.

Allicin is a bioactive compound with potent antioxidative activity and plays a protective effect in myocardial damage and fibrosis. The role and mechanism of Allicin in septic cardiomyopathy are unclear. In this study, we investigated the effects and underlying mechanisms of Allicin on lipopolysaccharide (LPS) induced injury in H9c2 cardiomyocytes. H9c2 cardiomyocyte cells were pretreated with Allicin (0, 25, 50, and 100 µM) for 2h, followed by incubation with LPS (10µg/mL) for 24h at 37°C. Cell viability (cell counting kit-8 [CCK-8]), apoptosis (TUNEL staining), oxidative stress (malondialdehyde [MDA] and superoxide dismutase [SOD]), and cytokines release (Interleukin beta [IL-β], Interleukin 6 [IL-6], and tumor necrosis factor-alpha [TNF-α]) were determined. The mRNA and protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and NLR family pyrin domain containing 3 (NLRP3) signaling pathway molecules were quantified by real-time quantitative PCR (RT-qPCR) and western blot, respectively. Allicin had no effect on H9c2 cell viability but attenuated LPS-induced injury, with increased cell viability, reduction in inflammatory cytokines release, apoptosis, reduced MDA, and increased SOD (P < 0.05). Additionally, Allicin increased Nrf2 and cellular HO-1 expressions in LPS-treated H9c2 cells. Moreover, Allicin modulated the NLRP3 inflammasome, increased the cleaved caspase-1 (p10) protein, and attenuated the LPS-induced increase in NLRP3, pro-IL-1β, and IL-1β proteins. Silencing of Nrf2 by siRNA (siNrf2) significantly attenuated Allicin-induced increase in cell viability and HO-1 and decrease in NLRP3 protein in LPS-stimulated H9c2 cells. Allicin protects cardiomyocytes against LPS‑induced injury through activation of Nrf2/HO-1 and inhibition of NLRP3 signaling pathways.

An updated view on the role of the female reproductive tract microbiome in IVF outcomes

Introduction. In the last decade, a high-throughput 16S ribosomal RNA (rRNA) sequencing allowed to markedly extend insights into female reproductive tract microbiome. However, evidence about its role on in vitro fertilization (IVF) outcomes remains scarce and controversial.Aim: to analyze literature data for assessing an impact of the vaginal, uterine, and ovarian microbiome on IVF outcomes.Materials and Methods. The review was carried out based on publications from available in PubMed/MEDLINE, EBSCO, ResearchGate, Google Academy and еLibrary databases released over the last 20 years. For this, there was search for keywords and their combinations in Russian- and English-written publications: «vaginal microbiome», «cervical microbiome», «uterine microbiome», «ovarian microbiome», «microbiome of ovarian follicles», «IVF», «miscarriage», «early pregnancy loss», «implantation failure», «ovarian failure», «inflammasome». Only full-text original articles and reviews published in peer-reviewed journals were included in the review. Exclusion criteria were as follows: studies containing less than 10 observations per group, abstracts of conferences, studies on the male reproductive tract microbiome. Duplicate publicationswere excluded. The publications were selected independently by two co-authors, and in case of discrepancy two other co-authors were involved.Results. Vaginal, uterine, and ovarian microbiomes were characterized by providing relevant classifications and the features related to implantation failures and pregnancy loss after IVF. It was found that a decline in total Lactobacillus level and elevated proportion of L. jensenii, G. vaginalis, and Proteobacteria in the vaginal microbiome were predictors of implantation failure. In addition, IVF failure was also associated with the presence of Atopobium, Bifidobacterium, Chryseobacterium, Gardnerella, Streptococcus, Haemophilus, Staphylococcus, Brevundimonas, and Ralstonia in the uterine cavity as well as Bifidobacterium, Gardnerella, and Klebsiella in the endometrial tissue. On the other hand, Lactobacillus dominance in the uterine microbiome has a favorable effect. The colonization of the follicle by any microorganisms as well as the presence of follicular fluid anaerobic bacteria-derived metabolite trimethylamine-N-oxide (TMAO) associated with bacterial vaginosis additionally alters IVF outcomes. Moreover, the role of infectious cues in lowered ovarian reserve has also been established. Activation of the NLRP3 (NLR Family Pyrin Domain Containing 3) inflammasome by microbe-derived ligands stimulates production of pro-inflammatory cytokines and contributes to reduced follicle number. Blocking NLRP3 in mouse experiments can delay depletion of the follicle pool and result in elevated fertility.Conclusion. Favorable IVF outcomes are associated with Lactobacillus predominance in the vaginal and endometrial microbiome as well as lack of follicular fluid microorganisms. TMAO detected in the follicular fluid as well as activated NLRP3 inflammasome serve as negative predictors of IVF outcomes.

Aucubin alleviates methotrexate-induced enteritis in rats by inducing autophagy.

One of the toxic side effects of methotrexate (MTX) is enteritis. Aucubin, an iridoid glycoside derived from traditional medicinal herbs, has been proven to have anti-inflammation, anti-apoptosis and anti-oxidation properties. This work explored the effect and mechanism of aucubin in treating MTX-induced enteritis in a rat model. Two doses of aucubin (5 and 10 mg/kg) were adopted for the assessment of its pharmacological activity. We observed that in rats with MTX-induced enteritis, the body weight and small intestinal weight decreased. The intestine barrier was injured, as reflected by pathological examinations and an increase in D-lactate and diamine oxidase concentration in serum. Intestinal inflammation was shown by the observation of macrophages in the intestine and the concentrations of inflammatory cytokines tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in serum. The NLR family pyrin domain containing 3 (NLRP3) inflammasome was shown to be activated by the enhancement of NLRP3, cleaved-caspase 1, IL-18 and IL-1β. Moreover, autophagy was reflected by transmission electron microscopy as slightly induced, along with changes in autophagy-related markers microtubule-associated protein 1 light chain 3 (LC3) and Beclin1. Remarkably, aucubin treatment attenuated the MTX-induced disease activity index increase, intestinal damage, inflammatory response and NLRP3 inflammasome activation, but provoked autophagy. Rapamycin, an autophagy activator, showed similar therapeutic effects to aucubin on MTX-induced enteritis. However, 3-methyladenine, an autophagy inhibitor, reversed the protective effects of aucubin. These findings prompted the hypothesis that aucubin alleviates MTX-induced enteritis by aggravating autophagy. This study might provide evidence for further investigation on the therapeutic role of aucubin in MTX-resulted enteritis.

Coffea arabica Extract Attenuates Atopic Dermatitis-like Skin Lesions by Regulating NLRP3 Inflammasome Expression and Skin Barrier Functions.

Atopic dermatitis (AD) is a common skin disease worldwide. The major causes of AD are skin barrier defects, immune dysfunction, and oxidative stress. In this study, we investigated the anti-oxidation and anti-inflammation effects of Coffea arabica extract (CAE) and its regulation of the skin barrier and immune functions in AD. In vitro experiments revealed that CAE decreased the reactive oxygen species levels and inhibited the translocation of nuclear factor-κB (NF-κB), further reducing the secretion of interleukin (IL)-1β and IL-6 induced by interferon-γ (IFN-γ)/tumor necrosis factor-α (TNF-α). Moreover, CAE decreased IFN-γ/TNF-α-induced NLR family pyrin domain-containing 3 (NLRP3), caspase-1, high-mobility group box 1 (HMGB1), and receptor for advanced glycation end products (RAGE) expression levels. It also restored the protein levels of skin barrier function-related markers including filaggrin and claudin-1. In vivo experiments revealed that CAE not only reduced the redness of the backs of mice caused by 2,4-dinitrochlorobenzene (DNCB) but also reduced the levels of pro-inflammatory factors in their skin. CAE also reduced transepidermal water loss (TEWL) and immune cell infiltration in DNCB-treated mice. Overall, CAE exerted anti-oxidation and anti-inflammation effects and ameliorated skin barrier dysfunction, suggesting its potential as an active ingredient for AD treatment.

Salvianolic acid B inhibits atherosclerosis and TNF-α-induced inflammation by regulating NF-κB/NLRP3 signaling pathway

BackgroundInflammation is critical in the pathophysiology of atherosclerosis (AS). The aim of this study was to investigate the protective effect of salvianolic acid B (Sal B) on AS and to explore the molecular mechanism of tumor necrosis factor-α (TNF-α)-induced damage in human umbilical vein endothelial cells (HUVECs). MethodsIn vivo studies, LDLR−/− mice were fed a high-fat diet (HFD) for 14 weeks to establish an AS model to evaluate the protective effect of Sal B on the development of AS. Total cholesterol (TC), triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) levels were determined in the blood serum. En face and cross section lipid deposits were measured and quantified with Oil Red O staining. Hematoxylin and eosin (H&E) and Masson's trichrome staining were used to quantify atherosclerotic plaque size and collagen fiber content in aortic root sections. Reactive oxygen species (ROS) were detected in aortic root using dihydroethylenediamine (DHE) staining. Apoptosis rate was determined by TdT-mediated dUTP nick end labeling (TUNEL) staining. Immunofluorescence (IF) staining was used to detect the expression of the nuclear factor kappa-B (NF-κB) p65 and NOD-like receptor family pyrin domain containing 3 (NLRP3). To further investigate the protective effect of Sal B, we used TNF-α induced HUVECs inflammation model. We examined cell viability, lactate dehydrogenase (LDH) content, and ROS production. The transcription of NF-κB was evaluated by immunofluorescence. The mRNA levels of NLRP3, caspase-1, and IL-1β were detected by RT-PCR. Pyroptosis related proteins were detected by Western blot. ResultsThe change in the weight of the mice over time was an indication that Sal B had an effect on weight gain. In vivo studies: we were able to show that the serum lipids TC, TG and LDL-C were increased in the model group and that the treatment with Sal B reduced the levels of serum lipids. Histological staining showed that the LDLR−/− mice had a large amount of foam cell deposition accompanied by inflammatory cell infiltration and the formation of atherosclerotic plaques in theMOD group. The pathological abnormalities were significantly improved by Sal B treatment. ROS release and apoptosis were significantly increased after HFD in aortic root, which was attenuated by Sal B. IF results showed that the expression of NF-κB p65 and NLRP3 was significantly increased in the MOD group and significantly decreased in the Sal B group, suggesting that Sal B may act through the NF-κB/NLRP3 pathway. And in vitro studies: inflammatory damage of HUEVCs was induced by TNF-α, and Sal B treatmented significantly increased cell viability and reduced LDH release. It was also found that Sal B inhibited ROS level increase after TNF-α-induced HUEVCs. Activation of NF-κB p65 by TNF-α stimulation, NF-κB p65 is transferred to the nucleus. Sal B treatment could reverse this effect. RT-PCR and Western blot showed that Sal B affected NF-κB transcription and NLRP3 inflammasome activation and could significantly inhibit TNF-α-induced NLRP3 inflammasome activation. These results suggest that Sal B may participate in antiatherosclerotic and inflammatory responses through the NF-κB/NLRP3 pathway. ConclusionsThis study shows that Sal B ameliorates the development of AS lesions in HFD-induced LDLR−/− mice. Furthermore, under TNF-α conditions, Sal B reduced ROS release and reversed nuclear translocation of NF-κB, and inhibited atherosclerosis and inflammation by modulating the NF-κB/NLRP3 pathway.

Melatonin Alleviates Lipopolysaccharide-Induced Endometritis by Inhibiting the Activation of NLRP3 Inflammasome through Autophagy.

Bovine endometritis is characterized by reduced milk production and high rates of infertility. Prior research has indicated that melatonin may possess anti-inflammatory and antioxidant properties that can counteract the progression of inflammatory diseases. In this research, we attempted to elucidate the protective effects of melatonin on LPS-induced endometritis. The results obtained from enzyme-linked immunosorbent assay (ELISA) and quantitative real-time PCR (qRT-PCR) revealed that melatonin effectively reduced the production and release of pro-inflammatory cytokines in an LPS-induced bovine endometrial epithelial cell line (BEND cells). Furthermore, western blotting demonstrated that melatonin treatment reduced the expression levels of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome-related proteins, including NLRP3, activated caspase-1, and cleaved IL-1β. Importantly, we further demonstrated that the anti-inflammatory effect of melatonin on BEND cells was related to autophagy by western blotting. Moreover, we used western blotting to detect autophagy-related proteins, MitoSOX to detect mitochondrial reactive oxygen species production (mtROS), and mitochondrial membrane potential (MMP) assay to detect mitochondrial membrane potential. The administration of melatonin demonstrated a significant enhancement in autophagy within BEND cells, leading to the effective elimination of impaired mitochondria. This process resulted in a reduction in the generation of reactive oxygen species within the mitochondria, restoration of mitochondrial membrane potential, and inhibition of the NLRP3 inflammasome activation. Moreover, in a mouse model of LPS-induced endometritis, melatonin treatment repressed the expression of pro-inflammatory cytokines by ELISA and qRT-PCR, alleviated pathological changes by hematoxylin-eosin staining (H&E), and inhibited myeloperoxidase (MPO) activity. In conclusion, our study showed that melatonin inhibited the activation of the NLRP3 inflammasome in BEND cells through autophagy, which may provide a novel therapeutic strategy for bovine endometritis.

Nootkatone attenuates airway inflammation in asthmatic mice through repressing ROS-induced NLRP3 inflammasome activation.

Nootkatone (NKT) exhibits potential pharmacological activities including anti-oxidation and anti-inflammation. Nevertheless, little is known about the roles of NKT in asthmatic airway inflammation. In the study, mice were sensitized and challenged with ovalbumin (OVA) to establish experimental allergic asthma model. After treatment with NKT, lung tissues, peripheral blood, and bronchoalveolar lavage fluid (BALF) were collected to assess inflammatory cytokines, oxidative stress, and pathological alternations. The effects of NKT on regulating reactive oxygen species (ROS)-induced NLR family pyrin domain containing 3 (NLRP3) inflammasome activation was assessed in IL-13-treated BEAS-2B cell model. We found that NKT treatment decreased the production of Th2 inflammatory cytokines (IL-4, IL-5, and IL-13) in BALF and IgE levels in serum, and alleviated inflammatory cell penetration, goblet cell proliferation, collagen accumulation, and mucus hypersecretion in lung tissues. NKT treatment mitigated oxidative stress and NLRP3 inflammasome activation in asthmatic mice. IL-13 treatment induced oxidative stress and NLRP3-mediated pyroptosis in BEAS-2B bronchial epithelial cells, whereas these effects were blocked by NKT. NKT protected against airway remodeling, as indicated by decreased epithelial-mesenchymal transition. Taken together, these results demonstrate that NKT mitigates asthmatic airway inflammation by inhibiting ROS-triggered NLRP3 activation and may be a potential agent for treating asthma.

Nrf2/HO-1 blocks TXNIP/NLRP3 interaction via elimination of ROS in oxygen-glucose deprivation-induced neuronal necroptosis

Acute ischemic stroke (AIS) is known to trigger a cascade of inflammatory events that induces secondary tissue damages. As a type of regulated inflammatory cell death, necroptosis is associated with AIS, whilst its regulation during neuroinflammation is not well understood. In particular, the actual function of NOD-like-receptor family pyrin domain-containing-3(NLRP3) inflammasome in cortical neuronal necroptosis still not clear. Herein, we explored the function of nuclear factor erythroid-2 related factor-2 (Nrf2)/heme oxygenase-1 (HO-1) in oxygen-glucose deprivation (OGD) induced neuronal necroptosis and its underlying mechanism. To establish an in vitro model of neuronal necrosis, we used OGD/caspase-8 inhibitors (Q-VD-OPh, QVD) to treat rat primary cortical neurons (PCNs) after reoxygenation, wherein we found that the model cause an elevated ROS levels by mediating TXNIP/NLRP3 interactions, which in turn activated the NLRP3 inflammasome. Also, we observed that regulation of nuclear factor erythroid-2 related factor-2 (Nrf2) promoted heme oxygenase-1 (HO-1) expression and decreased TXNIP (a protein that relate oxidative stress to activation of inflammasome) and ROS levels, which negatively regulated the expression of OGD-induced activation of NLRP3 inflammasomes. In addition, HO-1 weakened NLRP3 inflammation body activation, which suggests that Nrf2-regulated HO-1 could block the interaction between TXNIP and NLRP3 in OGD/R-treated cortical neurons by inhibiting ROS production. Our study has discovered the importance of Nrf2/HO-1 signaling cascade for inhibiting inflammasome of NLRP3, which negatively regulated necrosis. Therefore, NLRP3 is considered a potential target for a novel neuroprotective approach, which can expand the therapeutic windows of stroke drugs.

Effects and clinical significance of NLRP3 inflammasome activated by IL-17A in CRSwNP

Objective: To investigate the effects and clinical significance of NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activated by interleukin (IL)-17A in chronic rhinosinusitis with nasal polyps (CRSwNP). Methods: Patients underwent nasal endoscopic surgery in the Third Affiliated Hospital of Sun Yat-sen University from January 2020 to December 2021 were collected, including 28 CRSwNP (including 19 males and 9 females, aged 19 to 67 years), 22 chronic rhinosinusitis without nasal polyps (CRSsNP) and 22 controls. qRT-PCR was used to detect the expressions of IL-17A, NLRP3, IL-1β and IL-18 in the three groups, and their correlations were analyzed. The positions of IL-17A, NLRP3 and IL-18 in nasal polys were analyzed by immunofluorescence. Western Blotting and ELISA were employed to detect the expression of NLRP3, IL-1β and IL-18 in the human nasal epithelial cells after using IL-17A stimulation or IL-17A receptor inhibitor. Immunofluorescence was used to observe the NLRP3, IL-1β, and IL-18 protein expression after IL-17A stimulating human nasal epithelial cells, and after the use of IL-17A receptor inhibitor and NLRP3 inhibitor MCC950. The correlations between NLRP3, IL-1β, IL-18 and CT scores, nasal endoscopic scores, visual analogue scale (VAS) scores, and sino-nasal outcome test (SNOT) 22 scores of CRSwNP patients were analyzed. SPSS 20.0 software was used for statistical analysis. Results: The expressions of IL-17A, NLRP3, IL-1β and IL-18 in the tissues of CRSwNP patients were significantly higher than those in CRSsNP group(P=0.018,P<0.001,P=0.005, P=0.016) and the control group(all P<0.001). IL-17A was positively correlated with the expression of NLRP3, IL-1β, and IL-18(r ralue was 0.643,0.650,0.629,respectively, all P<0.05). IL-17A, NLRP3, and IL-18 were co-localized in the epithelial propria of polyp tissue. IL-17A stimulated the expressions of NLRP3, IL-1β, and IL-18 in human nasal epithelial cells. After the use of IL-17A receptor inhibitor, the expressions of NLRP3, IL-1β, and IL-18 were significantly down-regulated. After the use of NLRP3 inhibitor MCC950, IL-17A was significantly down-regulated to promote the expression of NLRP3, IL-1β, and IL-18. The expressions of NLRP3, IL-1β and IL-18 were positively correlated with CT, nasal endoscopy, VAS, and SNOT22 scores in patients with CRSwNP. Conclusions: IL-17A promotes the release of IL-1β and IL-18 by activating the NLRP3 inflammasome and aggravates the severity of the disease in CRSwNP.

Immunologic and vascular biomarkers of mortality in critical COVID-19 in a South African cohort.

Biomarkers predicting mortality among critical Coronavirus disease 2019 (COVID-19) patients provide insight into the underlying pathophysiology of fatal disease and assist with triaging of cases in overburdened settings. However, data describing these biomarkers in Sub-Saharan African populations are sparse. We collected serum samples and corresponding clinical data from 87 patients with critical COVID-19 on day 1 of admission to the intensive care unit (ICU) of a tertiary hospital in Cape Town, South Africa, during the second wave of the COVID-19 pandemic. A second sample from the same patients was collected on day 7 of ICU admission. Patients were followed up until in-hospital death or hospital discharge. A custom-designed 52 biomarker panel was performed on the Luminex® platform. Data were analyzed for any association between biomarkers and mortality based on pre-determined functional groups, and individual analytes. Of 87 patients, 55 (63.2%) died and 32 (36.8%) survived. We found a dysregulated cytokine response in patients who died, with elevated levels of type-1 and type-2 cytokines, chemokines, and acute phase reactants, as well as reduced levels of regulatory T cell cytokines. Interleukin (IL)-15 and IL-18 were elevated in those who died, and levels reduced over time in those who survived. Procalcitonin (PCT), C-reactive protein, Endothelin-1 and vascular cell adhesion molecule-1 were elevated in those who died. These results show the pattern of dysregulation in critical COVID-19 in a Sub-Saharan African cohort. They suggest that fatal COVID-19 involved excessive activation of cytotoxic cells and the NLRP3 (nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3) inflammasome. Furthermore, superinfection and endothelial dysfunction with thrombosis might have contributed to mortality. HIV infection did not affect the outcome. A clinically relevant biosignature including PCT, pH and lymphocyte percentage on differential count, had an 84.8% sensitivity for mortality, and outperformed the Luminex-derived biosignature.

Neuroprotection of β-caryophyllene against cerebral ischemia/reperfusion injury by inhibiting P38 MAPK/NLRP3 signaling pathway.

The main objective of our research was to explore the neuroprotective effect and underlying mechanism of β-caryophyllene (BCP) pretreatment against cerebral ischemia/reperfusion injury (CIRI). Neurological deficit score, infarct size, and sensorimotor function were assessed 24 h following reperfusion. Additionally, histopathological damage of neurons was evaluated using hematoxylin-eosin staining. The mRNA level of nod-like receptor family pyrin domain-containing 3 (NLRP3) was determined using quantitative real-time PCR. The expressions of p-p38, p38, NLRP3, procaspase-1, and ASC (apoptosis-associated speck-like protein containing a CARD) were measured using western blot analysis. The levels of interleukin-1β (IL-1β) and interleukin-18 (IL-18) were quantified utilizing the ELISA. Our findings indicated that BCP pretreatment significantly reduced the infarct volume, neurologic deficit score, sensorimotor deficits, histopathological damage, and expression of inflammatory factors. Besides, BCP pretreatment effectively suppressed the expression of p-p38, as well as the activation of NLRP3 inflammasome. The administration of anisomycin, an activator of p38 MAPK, was found to notably impede the favorable outcomes conferred by BCP pretreatment, which included reducing the infarct volume, improving the neurologic deficit score, mitigating the sensorimotor deficits, and attenuating the histopathological damage. Furthermore, anisomycin effectively reversed the suppressive impact of BCP on NLRP3 inflammasome activation. This research uncovered that pretreatment with BCP has the potential to alleviate CIRI by effectively suppressing the activation of NLRP3 inflammasome through the p38 MAPK signaling pathway.

Ozonated triglyceride protects against septic lethality via preventing the activation of NLRP3 inflammasome.

Sepsis is a critical dysregulated host response with high mortality and current treatment is difficult to achieve optimal efficacy. Ozone therapy has been revealed to protect infection and inflammation-related diseases due to its role in antibiotic and immunoregulatory effect. Ozonated triglyceride is a key component of ozonated oil that is one of ozone therapy dosage form. However, the potential role of ozonated triglyceride in sepsis remains unclear. This study aims to explore the effect of ozonated triglyceride on septic mouse model and the molecular mechanism. Intraperitoneal injection of lipopolysaccharide (LPS), cecal ligation and puncture (CLP) were applied to construct septic mouse model. The mouse serum was obtained for detection of cytokines, and lung tissues were collected for hematoxylin and eosin (HE) staining to evaluate the extent of lung injury in septic mouse with ozonated triglyceride treatment at different time and doses. The survival of septic mice was observed for 96 h and Kaplan-Meier analysis was used to analyze the survival rates. In addition, primary peritoneal macrophages and human acute monocytic-leukemia cell line (THP-1) were treated with inflammasome activators with or without ozonated triglyceride. The level of cytokines was detected by enzyme-linked immunosorbent assay (ELISA). The cleavage of caspase-1 and gasdermin-D (GSDMD) was detected by Western blotting. Ozonated triglyceride at different time and doses reduced the release of inflammasome-related cytokines [interleukin (IL)-1β and IL-18] (all P<0.05) but not pro-inflammatory cytokines such as IL-6 and tumor necrosis factor-α (TNF-α) in septic mice (all P>0.05). Ozonated triglyceride significantly improved the survival rate of septic mice and reduced sepsis-induced lung injury (all P<0.05). Ozonated triglyceride significantly suppressed the canonical and non-canonical activation of NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome (all P<0.05) but not affected absent in melanoma 2 (AIM2) and NLR family CARD domain-containing protein 4 (NLRC4) inflammasomes in vitro (all P>0.05). Ozonated triglyceride reduced the cleavage of caspase-1 and the downstream GSDMD. Ozonated triglyceride presents a protect effect on sepsis lethality via reducing cytokines release and sepsis-related organ injury. The mechanism is that ozonated triglyceride specifically suppresses the activation of NLRP3 inflammasome. Ozonated triglyceride is a promising candidate for sepsis treatment.

Reduction of high glucose-induced oxidative injury in human retinal pigment epithelial cells by sarsasapogenin through inhibition of ROS generation and inactivation of NF-κB/NLRP3 inflammasome pathway.

Hyperglycemia-induced accumulation of reactive oxygen species (ROS) is a major risk factor for diabetic retinopathy (DR). Sarsasapogenin is a natural steroidal saponin that is known to have excellent antidiabetic effects and improve diabetic complications, but its potential efficacy and mechanism for DR are unknown. The current study was designed to explore whether sarsasapogenin inhibits hyperglycemia-induced oxidative stress in human retinal pigment epithelial (RPE) ARPE-19 cells and to elucidate the molecular mechanisms. To mimic hyperglycemic conditions, ARPE-19 cells were cultured in medium containing high glucose (HG). The suppressive effects of sarsasapogenin on HG-induced cell viability reduction, apoptosis and ROS production were investigated. In addition, the relevance of the nuclear factor-kappa B (NF-κB)/NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome signaling pathway was explored to investigate the mechanism of antioxidant and anti-inflammatory activity of sarsasapogenin. Sarsasapogenin significantly alleviated cytotoxicity and apoptosis in HG-treated ARPE-19 cells through inhibition of intracellular ROS generation. Sarsasapogenin also effectively attenuated HG-induced excess accumulation of mitochondrial superoxide, reduction of glutathione content, and inactivation of manganese superoxide dismutase and glutathione peroxidase. The HG condition markedly increased the expression and maturation of interleukin (IL)-1β and IL-18 through the activation of the NF-kB signaling pathway, whereas sarsasapogenin reversed these effects. Moreover, although the expression of NLRP3 inflammasome multiprotein complex molecules was increased in ARPE-19 cells cultured under HG conditions, their levels remained similar to the control group in the presence of sarsasapogenin. Sarsasapogenin could protect RPE cells from HG-induced injury by inhibiting ROS generation and NF-κB/NLRP3 inflammasome pathway, suggesting its potential as a therapeutic agent to improve the symptoms of DR.

Vitamin D3 attenuates SARS-CoV-2 nucleocapsid protein-caused hyperinflammation by inactivating the NLRP3 inflammasome through the VDR-BRCC3 signaling pathway in vitro and in vivo.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-caused coronavirus disease 2019 (COVID-19) is a global crisis with no satisfactory therapies. Vitamin D3 (VD3) is considered a potential candidate for COVID-19 treatment; however, little information is available regarding the exact effects of VD3 on SARS-CoV-2 infection and the underlying mechanism. Herein, we confirmed that VD3 reduced SARS-CoV-2 nucleocapsid (N) protein-caused hyperinflammation in human bronchial epithelial (HBE) cells. Meanwhile, VD3 inhibited the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation in N protein-overexpressed HBE (HBE-N) cells. Notably, the inhibitors of caspase-1, NLRP3, and NLRP3 or caspase-1 small interference RNA (siRNA) enhanced VD3-induced NLRP3 inflammasome inactivation, with subsequent suppression of interleukin-6 (IL6) and IL1β release in HBE-N cells, which were abolished by the NLRP3 agonist. Moreover, VD3 increased NLRP3 ubiquitination (Ub-NLRP3) expression and the binding of the VDR with NLRP3, with decreased BRCA1/BRCA2-containing complex subunit 3 (BRCC3) expression and NLRP3-BRCC3 association. VD3-induced Ub-NLRP3 expression, NLRP3 inflammasome inactivation, and hyperinflammation inhibition were improved by the BRCC3 inhibitor or BRCC3 siRNA, which were attenuated by the vitamin D receptor (VDR) antagonist or VDR siRNA in HBE-N cells. Finally, the results of the in vivo study in AAV-Lung-enhanced green fluorescent protein-N-infected lungs were consistent with the findings of the in vitro experiment. In conclusion, VD3 attenuated N protein-caused hyperinflammation by inactivating the NLRP3 inflammasome partially through the VDR-BRCC3 signaling pathway.

Hepatitis E virus infection remodels the mature tRNAome in macrophages to orchestrate NLRP3 inflammasome response

Hepatitis E virus (HEV) infection has been shown to activate NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome in macrophages, a key mechanism of causing pathological inflammation, but the mechanisms regulating this response remain poorly understood. Here, we report that the mature tRNAome dynamically responds to HEV infection in macrophages. This directs IL-1β expression, the hallmark of NLRP3 inflammasome activation, at mRNA and protein levels. Conversely, pharmacological inhibition of inflammasome activation abrogates HEV-provoked tRNAome remodeling, revealing a reciprocal interaction between the mature tRNAome and the NLRP3 inflammasome response. Remodeling the tRNAome results in improved decoding of codons directing leucine- and proline synthesis, which are the major amino acid constituents of IL-1β protein, whereas genetic or functional interference with tRNAome-mediated leucine decoding impairs inflammasome activation. Finally, we demonstrated that the mature tRNAome also actively responds to lipopolysaccharide (a key component of gram-negative bacteria)-triggered inflammasome activation, but the response dynamics and mode of actions are distinct from that induced by HEV infection. Our findings thus reveal the mature tRNAome as a previously unrecognized but essential mediator of host response to pathogens and represent a unique target for developing anti-inflammatory therapeutics.

Medicinal Plants, Phytochemicals and Regulation of the NLRP3 Inflammasome in Inflammatory Bowel Diseases: A Comprehensive Review

Ongoing research explores the underlying causes of ulcerative colitis and Crohn’s disease. Many experts suggest that dysbiosis in the gut microbiota and genetic, immunological, and environmental factors play significant roles. The term “microbiota” pertains to the collective community of microorganisms, including bacteria, viruses, and fungi, that reside within the gastrointestinal tract, with a particular emphasis on the colon. When there is an imbalance or disruption in the composition of the gut microbiota, it is referred to as dysbiosis. Dysbiosis can trigger inflammation in the intestinal cells and disrupt the innate immune system, leading to oxidative stress, redox signaling, electrophilic stress, and inflammation. The Nod-like Receptor (NLR) Family Pyrin Domain Containing 3 (NLRP3) inflammasome, a key regulator found in immunological and epithelial cells, is crucial in inducing inflammatory diseases, promoting immune responses to the gut microbiota, and regulating the integrity of the intestinal epithelium. Its downstream effectors include caspase-1 and interleukin (IL)-1β. The present study investigated the therapeutic potential of 13 medicinal plants, such as Litsea cubeba, Artemisia anomala, Piper nigrum, Morus macroura, and Agrimonia pilosa, and 29 phytocompounds such as artemisitene, morroniside, protopine, ferulic acid, quercetin, picroside II, and hydroxytyrosol on in vitro and in vivo models of inflammatory bowel diseases (IBD), with a focus on their effects on the NLRP3 inflammasome. The observed effects of these treatments included reductions in IL-1β, tumor necrosis factor-alpha, IL-6, interferon-gamma, and caspase levels, and increased expression of antioxidant enzymes, IL-4, and IL-10, as well as regulation of gut microbiota. These effects could potentially provide substantial advantages in treating IBD with few or no adverse effects as caused by synthetic anti-inflammatory and immunomodulated drugs. However, additional research is necessary to validate these findings clinically and to develop effective treatments that can benefit individuals who suffer from these diseases.

Effect of NLRP3 inflammasome genes polymorphism on disease susceptibility and response to TNF-α inhibitors in Iraqi patients with rheumatoid arthritis

BackgroundRheumatoid arthritis (RA) is a genetically predisposed, systemic, chronic, inflammatory disease. Immune system dysregulation and inherited susceptibility polymorphisms suggest that this type of variation is functional and may help predict disease susceptibility and develop new therapeutic strategies. Anti-TNF-alpha (TNF-α) drugs are highly effective RA treatments, but not all patients respond the same way. It's important to figure out whether RA risk alleles can identify and predict anti-TNF-α-responsiveness in RA patients. Aims of the studyExamine the function of the NLR family pyrin domain containing 3 (NLRP3) and caspase recruitment domain family member 8 (CARD8) genes polymorphisms and their morbid genotypes and alleles in RA patients and apparently healthy controls. In addition, their role in disease susceptibility, severity, and response to anti-TNF-α therapy. Also, examine how single nucleotide polymorphisms (SNPs) affect serum levels of pro-inflammatory cytokines like TNF-α and interleukin (IL)-1β. Materials and methods100 RA patients (88 females, 12 males) and 100 apparently healthy people (86 females, 14 males) were examined. To measure serum TNF-α and IL-1β, Elabscience sandwich ELISA kits were used. Iraq Biotech, Turkey DNA extraction kit was used to extract genomic DNA from whole blood. CARD8 (rs2043211) and NLRP3 (rs4612666) were genotyped using Agilent, AriaMx, USA, through Tri-Plex SYBR Green-based real-time PCR allelic discrimination assays. Geneious software, version 2019.2.2, used to design primers from published sequences (GenBank accession no. GCA 009914755.1). Primer specificity was determined by NCBI's BLAST. ResultsStudy found that there is association between cytokines serum level and 28-joints disease activity score (DAS-28). The level of TNF-α increases with the higher DAS-28 (r2 = 0.45, P < 0.0001). Also, IL- 1β level increases with higher DAS-28 (r2 = 0.51, P < 0.0001). There were no statistically significant variations between patients with RA and the control group in the distribution of CARD8 SNP rs2043211 and NLRP3 SNP rs4612666 genotypes (P = 0.17 and 0.08 respectively) as well their alleles (P = 0.059 and 0.879 respectively). CARD8 (rs2043211) TT genotype was more frequent in patients with higher DAS-28 (P < 0.0001) and higher TNF-α and IL-1β serum levels (P < 0.0001 for both). Also, NLRP3 (rs4612666) TT genotype was more frequent in patients with higher DAS-28 (P < 0.0001) and higher TNF-α and IL- 1β serum levels (P < 0.0001 for both). Interestingly, this study revealed that CARD8 (rs2043211) and NLRP3 (rs4612666) variant genotypes are associated with lower response to anti-TNF-α drugs. ConclusionsSerum TNF-α and IL-1β correlate with DAS-28 and disease activity. Non-responders have elevated TNF-α and IL-1β. CARD8 rs2043211 and NLRP3 rs4612666 variant polymorphisms are associated with high serum TNF-α and IL-1β, active disease course, poor disease outcomes, and low response to anti-TNF-α therapy.