Inflammasome-related Gene Research Articles

NLRP3 gene polymorphisms in Iranian patients with recurrent aphthous stomatitis.

Recurrent aphthous stomatitis (RAS) is a common disorder with an unclear etiopathogenesis. Involvement of the immune system in the development of this condition is strongly suggested. As the variations in the inflammasome-related NLRP3 gene have been suggested to affect immune system activity, this case-control study was performed to determine whether these genetic variants are associated with RAS. We studied a group of 69 Iranian patients with RAS in comparison with 56 healthy controls. We determined four single nucleotide polymorphisms (SNPs) of NLRP3 and performed association analyses of NLRP3. Genotyping was conducted using the TaqMan method. The NLRP3 rs3806265 T allele was significantly more frequent in the patients with RAS than in the healthy controls (P=0.003). While a significant negative association was found between the C allele at the same position with RAS (P=0.003), the TT genotype was significantly more frequent at position rs3806265 in NLRP3 in patient group than in the controls (P=0.002). However, the frequency of CT genotype at the same position was significantly higher in healthy controls than in the case category (P=0.002). Considering the high frequency of the presence of NLRP3 rs3806265 TT genotype in patients with RAS, it seems that this gene polymorphism could affect individual susceptibility to RAS.

Caspase-1/ASC inflammasome-mediated activation of IL-1β-ROS-NF-κB pathway for control of Trypanosoma cruzi replication and survival is dispensable in NLRP3-/- macrophages.

In this study, we have utilized wild-type (WT), ASC−/−, and NLRP3−/− macrophages and inhibition approaches to investigate the mechanisms of inflammasome activation and their role in Trypanosoma cruzi infection. We also probed human macrophages and analyzed published microarray datasets from human fibroblasts, and endothelial and smooth muscle cells for T. cruzi-induced changes in the expression genes included in the RT Profiler Human Inflammasome arrays. T. cruzi infection elicited a subdued and delayed activation of inflammasome-related gene expression and IL-1β production in mφs in comparison to LPS-treated controls. When WT and ASC−/− macrophages were treated with inhibitors of caspase-1, IL-1β, or NADPH oxidase, we found that IL-1β production by caspase-1/ASC inflammasome required reactive oxygen species (ROS) as a secondary signal. Moreover, IL-1β regulated NF-κB signaling of inflammatory cytokine gene expression and, subsequently, intracellular parasite replication in macrophages. NLRP3−/− macrophages, despite an inability to elicit IL-1β activation and inflammatory cytokine gene expression, exhibited a 4-fold decline in intracellular parasites in comparison to that noted in matched WT controls. NLRP3−/− macrophages were not refractory to T. cruzi, and instead exhibited a very high basal level of ROS (>100-fold higher than WT controls) that was maintained after infection in an IL-1β-independent manner and contributed to efficient parasite killing. We conclude that caspase-1/ASC inflammasomes play a significant role in the activation of IL-1β/ROS and NF-κB signaling of cytokine gene expression for T. cruzi control in human and mouse macrophages. However, NLRP3-mediated IL-1β/NFκB activation is dispensable and compensated for by ROS-mediated control of T. cruzi replication and survival in macrophages.

Increased inflammasome related gene expression profile in PBMC may facilitate T helper 17 cell induction in multiple sclerosis

The NLRP3 inflammasome is a macromolecular complex importantly involved in IL-1β processing. A role for this has been described in multiple sclerosis (MS). One mechanism by which IL-1β might be involved in MS is by inducing pathogenic Th17 cells, i.e. GM-CSF+ Th17 cells. In the present study, we show that expression of the inflammasome related genes, NLRP3, caspase-1, IL-1β and the IL-1β/IL-1Ra ratio, was increased in PBMC from MS patients compared to healthy controls (HC). However, in an in vitro inflammasome activity assay with PBMC, IL-1β protein secretion and the IL-1β/IL-1Ra protein ratio were similar in MS patients and HC. Th cells cultured in the presence of supernatant derived from LPS/ATP inflammasome activated PBMC showed increased Th17 and GM-CSF+ Th17 cell frequencies in HC and MS patients and decreased anti-inflammatory IL-10+Th cell frequency in HC compared to Th cells cultured in the presence of control supernatant. Moreover, addition of the immune modulator calcitriol to the former condition resulted in reduced frequencies of Th17 and GM-CSF+Th17 cells, and also of IL-10+ Th cells. Evidently, our data indicate that inflammasome activity can skew the Th cell population toward a more pro-inflammatory composition, an effect that might be inhibited by vitamin D, and that might be importantly involved in inflammation within the central nervous system.

Curcumin: A Double Hit on Malignant Mesothelioma

Inflammation is a key mediator in the development of malignant mesothelioma, which has a dismal prognosis and poor therapeutic strategies. Curcumin, a naturally occurring polyphenol in turmeric, has been shown to possess anticarcinogenic properties through its anti-inflammatory effects. Inflammasomes, a component of inflammation, control the activation of caspase-1 leading to pyroptosis and processing of proinflammatory cytokines, interleukin (IL)-1β and IL-18. In the present study, we investigate the role of curcumin in pyroptotic cell death of malignant mesothelioma cells. Using in vitro models with mouse and human malignant mesothelioma cells, curcumin is shown to induce pyroptosis through activation of caspase-1 and increased release of high-mobility group box 1 (HMGB1) without processing of IL-1β and IL-18. Absence of IL-1β processing in response to curcumin-mediated caspase-1 activation is attributed to blockade of pro-IL-1β priming through inhibition of the NF-κB pathway. Furthermore, curcumin's cytotoxicity in malignant mesothelioma cells is demonstrated to be dependent on pyroptosis as inhibition of caspase-1 resulted in protection against curcumin-induced cell death. We also demonstrate that curcumin-mediated caspase-1 activation is oxidant dependent by using N-acetyl-L-cysteine (NAC) to inhibit pyroptosis. PCR array analysis using the human inflammasome template revealed that curcumin significantly downregulated levels of inflammasome-related gene expression involved in inflammation, e.g., NF-κB, toll-like receptors (TLR), and IL-1β. Our data indicate that curcumin has a double effect on malignant mesothelioma cells through induction of pyroptosis while subsequently protecting against inflammation.

Inflammasome Activation by Cystine Crystals

Intralysosomal cystine crystal accumulation, due to mutations in the CTNS gene, is a hallmark of nephropathic cystinosis, but the role of these crystals in disease pathogenesis remains unclear. We hypothesized that, similar to other host-derived crystalline moieties, cystine crystals can induce IL-1β production through inflammasome activation. Thus, we investigated the proinflammatory effects of cystine crystals in primary human PBMCs. LPS-primed PBMCs stimulated with cystine crystals secreted IL-1β in a dose-dependent manner. Similarly to IL-1β secretion induced by other crystalline inflammasome activators, cystine crystal-induced IL-1β secretion required activation of caspase-1. Additionally, exogenous cystine crystals were internalized by monocytes, and inhibition of phagocytosis, cathepsin B leakage, generation of reactive oxygen species, and potassium efflux reduced cystine crystal-induced IL-1β secretion. Patients with cystinosis had higher levels of circulating IL-1β and IL-18 compared with controls. Analysis of inflammasome-related gene expression in PBMCs from patients with cystinosis revealed a significant increase in IL-1β and CASP-1 transcript levels compared with controls. Moreover, knockout of cystinosin in mice led to significant increases in serum IL-18 levels and kidney expression of inflammasome-related genes (Casp-1, Pycard, Il-18, Il18r1, Il1r1, and Il1rl2). Taken together, these data demonstrate that cystine crystals are endogenous inflammasome-activating stimuli, suggesting a novel role for cystine crystals in the pathogenesis of nephropathic cystinosis.

Q705K variant in NLRP3 gene confers protection against myocardial infarction in female individuals.

Inflammation is a multifaceted process that underlies the pathophysiology of acute myocardial infarction (MI). Variations in the inflammasome-related NLRP3 gene have been associated with risk for a number of different inflammatory diseases. Therefore, Q705K polymorphism in NLRP3 gene likely confers susceptibility to risk for MI. A First-ever myocardial Infarction study in Ac-county (FIA) cohort comprising 555 MI patients and 1,016 controls was used to genotype rs35829419 in the NLRP3 gene by TaqMan single-nucleotide polymorphism assay. C-reactive protein (CRP) was measured in the study participants by ELISA. The results showed no significant association between the variant rs35829419 and MI. However, the minor A allele of the rs35829419 polymorphism conferred a protective effect against the risk of developing MI in females. The minor A allele of rs35829419 polymorphism was also associated with increased CRP levels in males. Results of the study suggested a gender-specific deregulation of NLRP3 gene mediated by rs35829419 polymorphism that confers protection against MI in females but has no effect on MI susceptibility in males. However, the rs35829419 polymorphism was associated with increased CRP levels among the male subjects, thereby demonstrating the possible effect of the Q705K polymorphism in elevating the basal active state of innate immune response.