Role of genetic alterations in the NLRP3 and CARD8 genes in health and disease

JT002, a small molecule inhibitor of the NLRP3 inflammasome for the treatment of autoinflammatory disorders

The NLRP3 inflammasome is an intracellular, multiprotein complex that promotes the auto-catalytic activation of caspase-1 and the subsequent maturation and secretion of the pro-inflammatory cytokines, IL-1β and IL-18. Persistent activation of the NLRP3 inflammasome has been implicated in the pathophysiology of a number of inflammatory and autoimmune diseases, including neuroinflammation, cardiovascular disease, non-alcoholic steatohepatitis, lupus nephritis and severe asthma. Here we describe the preclinical profile of JT002, a novel small molecule inhibitor of the NLRP3 inflammasome. JT002 potently reduced NLRP3-dependent proinflammatory cytokine production across a number of cellular assays and prevented pyroptosis, an inflammatory form of cell death triggered by active caspase-1. JT002 demonstrated in vivo target engagement at therapeutically relevant concentrations when orally dosed in mice and prevented body weight loss and improved inflammatory and fibrotic endpoints in a model of Muckle-Wells syndrome (MWS). In two distinct models of neutrophilic airway inflammation, JT002 treatment significantly reduced airway hyperresponsiveness and airway neutrophilia. These results provide a rationale for the therapeutic targeting of the NLRP3 inflammasome in severe asthma and point to the use of JT002 in a variety of inflammatory disorders.

Variants of CARD8 in Leishmania guyanensis-cutaneous leishmaniasis and influence of the variants genotypes on circulating plasma cytokines IL-1β, TNFα and IL-8

Nucleotide-binding oligomerization domain, leucine-rich repeat-containing protein family (NLR) are intracellular pathogen recognition receptors mediating innate immunity, releasing proinflammatory cytokines IL-1β and IL-18, and promoting pyroptotic cell death, upon sensing pathogenic or endogenous danger signals. In animal models, NLRP3 inflammasome has a dual role, pathogenic or protective in Leishmania-infection, depending on the Leishmania species and mice strain. Caspase recruitment containing domain 8 (CARD8) is a negative regulator of NLRP3 inflammasome and also an inhibitor of transcription factor NFĸB, a major transcription factor of proinflammatory cytokines. We investigated whether single nucleotide variants in CARD8 may partially explain why only a proportion of individuals coming from the same area of endemicity of leishmaniasis develop cutaneous leishmaniasis caused by Leishmania guyanensis. We genotyped four single nucleotide variants of the CARD8 gene by direct nucleotide sequencing in 1741 individuals from an endemic area of leishmaniasis, constituting 850 patients with CL and 891 healthy controls. The frequencies of the genotypes of the variants rs2288877 T>C, rs73944113 C>T, and rs2043211 A>T are similar among the patients with CL and HC, while the variant rs2288876 A>G) reveals an excess of the genotype AA among the patients with CL (44%) compared to 37% in the HC group. Allele A of the variant rs2288876 A>G) is associated with susceptibility to CL (OR = 1.2 [95%CI 1.03-1.4]; P = 0.01). Haplotype analysis showed that individuals harboring the haplotype CCAA have 280% odds of developing CL caused by L. guyanensis (OR = 3.8 [95% CI 2.0-7.7]; p = 0.00004). The variants rs2288877 T>C and rs2288876 A>G correlate with the plasma level of IL-8. Spearman correlation showed a significant positive correlation between the rs2288876 A>G allele A and the level of IL-8 (ρ = 0.22; p = 0.0002). CARD8 may partially contribute to the development of CL caused by L. guyanensis.

Viral proteases activate the CARD8 inflammasome in the human cardiovascular system

Nucleotide-binding oligomerization domain (NBD), leucine-rich repeat (LRR) containing protein family (NLRs) are intracellular pattern recognition receptors that mediate innate immunity against infections. The endothelium is the first line of defense against blood-borne pathogens, but it is unclear which NLRs control endothelial cell (EC) intrinsic immunity. Here, we demonstrate that human ECs simultaneously activate NLRP1 and CARD8 inflammasomes in response to DPP8/9 inhibitor Val-boro-Pro (VbP). Enterovirus Coxsackie virus B3 (CVB3)-the most common cause of viral myocarditis-predominantly activates CARD8 in ECs in a manner that requires viral 2A and 3C protease cleavage at CARD8 p.G38 and proteasome function. Genetic deletion of CARD8 in ECs and human embryonic stem cell-derived cardiomyocytes (HCMs) attenuates CVB3-induced pyroptosis, inflammation, and viral propagation. Furthermore, using a stratified endothelial-cardiomyocyte co-culture system, we demonstrate that deleting CARD8 in ECs reduces CVB3 infection of the underlying cardiomyocytes. Our study uncovers the unique role of CARD8 inflammasome in endothelium-intrinsic anti-viral immunity.

Convergence of signalling pathways in innate immune responses and genetic forms of Parkinson's disease

In recent years progress in molecular biology and genetics have advanced our understanding of neurological disorders and highlighted synergistic relationships with inflammatory and age-related processes. Parkinson's disease (PD) is a common neurodegenerative disorder that is characterized by loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Increasing extensive evidence supports the contribution of genetic risk variants and inflammation in the pathobiology of this disease. Functional and genetic studies demonstrate an overlap between genes linked to increased risk for PD and autoimmune diseases. Variants identified in loci adjacent to LRRK2, GBA, and HLA establish a crosstalk between the pathobiologies of the two disease spectra. Furthermore, common signalling pathways associated with the pathogenesis of genetic PD are also relevant to inflammatory signaling include MAPK, NF-κB, Wnt and inflammasome signaling. Importantly, post-mortem analyses of brain and cerebrospinal fluid from PD patients show the accumulation of proinflammatory cytokines. In this review we will focus on the principal mechanisms of genetic, inflammatory and age-related risk that intersect in the pathogenesis of PD.

Activation and Function of NLRP3 Inflammasome in Bone and Joint-Related Diseases

Inflammation is a pivotal response to a variety of stimuli, and inflammatory molecules such as cytokines have central roles in the pathogenesis of various diseases, including bone and joint diseases. Proinflammatory cytokines are mainly produced by immune cells and mediate inflammatory and innate immune responses. Additionally, proinflammatory cytokines accelerate bone resorption and cartilage destruction, resulting in the destruction of bone and joint tissues. Thus, proinflammatory cytokines are involved in regulating the pathogenesis of bone and joint diseases. Interleukin (IL)-1 is a representative inflammatory cytokine that strongly promotes bone and cartilage destruction, and elucidating the regulation of IL-1 will advance our understanding of the onset and progression of bone and joint diseases. IL-1 has two isoforms, IL-1α and IL-1β. Both isoforms signal through the same IL-1 receptor type 1, but the activation mechanisms are completely different. In particular, IL-1β is tightly regulated by protein complexes termed inflammasomes. Recent research using innovative technologies has led to a series of discoveries about inflammasomes. This review highlights the current understanding of the activation and function of the NLRP3 (NOD-like receptor family, pyrin domain-containing 3) inflammasome in bone and joint diseases.

Combined effects of nucleotide-binding domain-like receptor protein 3 polymorphisms and environmental metals exposure on chronic kidney disease

Chronic inflammation is the cause of chronic kidney disease (CKD). The nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome plays a vital role in the inflammation process and is associated with the regulatory effects of NLRP3 gene polymorphisms. This study evaluated the association between NLRP3 gene polymorphisms and CKD, and further explored whether the association of environmental metals with CKD varied by the NLRP3 genotypes. A total of 218 CKD patients and 427 age- and sex-matched healthy controls were recruited in this clinic-based case-control study. Patients were identified as having CKD if their estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² and stage 3-5 for at least 3 months. We examined the genotypes of fifteen common ssingle-nucleotide polymorphisms in NLRP3 genes. Concentrations of total urinary arsenic were examined by summing of urinary inorganic arsenic species. Concentrations of selenium, cadmium, and lead were measured from blood samples. Associations between NLRP3 polymorphisms, environmental metals exposure, and CKD were evaluated using multivariable logistic regression while controlling for confounders. We observed that the odds of carrying NLRP3 rs4925650 GA/AA genotypes, NLRP3 rs1539019 CA/AA genotypes, and NLRP3 rs10157379 CT/TT genotypes were significantly higher among CKD cases compared to controls, with the adjusted odds ratio (95% confidence interval) were 1.54 (1.01-2.36), 1.56 (1.04-2.33), and 1.59 (1.05-2.38), respectively. The significant multiplicative interactions were identified between high levels of blood lead and NLRP3 rs4925650 GA/AA genotypes; high levels of blood cadmium or low levels of plasma selenium and the NLRP3 haplotype (rs4925648, rs4925650, rs12048215, and rs10754555) C-A-A-C multiplicatively interacted to increase the risk of CKD. Our results imply that NLRP3 polymorphisms may play an important role in the development of environmental metals exposure related CKD.

Associations between inflammasome-related gene NLRP3 Polymorphisms (rs10754558 and rs35829419) and risk of bladder cancer in a Chinese population

Background

NLRP3 inflammasome as a component of immune system has been found related to several cancers, but no study has assessed NLRP3 polymorphisms on risk of bladder cancer (BC). We aim to investigate whether NLRP3 polymorphisms are associated with the risk and clinical features of bladder cancer (BC) in a Chinese population.

Methods

Genotype frequency of two commonly studied NLRP3 SNPs (rs10754558 and rs35829419) was examined in 154 patients with BC and the 308 healthy controls. NLRP3 gene polymorphisms were genotyped by polymerase chain reaction‐restriction fragment length polymorphism method.

Results

The distribution frequencies of GG, AG+GG, GG, and G allele in NLRP3 (rs10754558) genotypes were significantly different between case and control group (OR = 2.296, P = .022; OR = 1.598, P = .020; OR = 1.998, P = .049; OR = 1.557, P = .006), but no statistical difference existed for rs35829419. Among smokers and alcohol drinkers, for rs10754558, individuals with AG, GG, and GG+AG genotypes had a higher BC risk compared with individuals with AA; for rs35829419, individuals with variant genotypes (AG and GG+AG) had a stronger risk of developing BC compared with individuals with AA (all P < .05). In stratified analyses of tumor size and tumor node metastasis, AG or GG genotypes of rs10754558 and rs35829419 SNPs were associated with BC risk (both P < .05).

Conclusion

NLRP3 polymorphisms (rs10754558 and rs35829419) were related to BC risk and tumor size and lymph node metastasis, especially among smokers and alcohol drinkers.

Activation of the Adipose Tissue NLRP3 Inflammasome Pathway in Cancer Cachexia

Background

Cachexia is a paraneoplastic syndrome that accompanies and compromises cancer treatment, especially in advanced stages, affecting the metabolism and function of several organs. The adipose tissue is the first to respond to the presence of the tumor, contributing to the secretion of factors which drive the systemic inflammation, a hallmark of the syndrome. While inflammation is a defensive innate response, the control mechanisms have been reported to be disrupted in cachexia. On the other hand, little is known about the role of NLRP3 inflammasome in this scenario, a multiprotein complex involved in caspase-1 activation and the processing of the cytokines IL-1β and IL-18.

Aim

based on the evidence from our previous study with a rodent model of cachexia, we examined the activation of the NLRP3 inflammasome pathway in two adipose tissue depots obtained from patients with colorectal cancer and compared with that another inflammatory pathway, NF-κB.

Results

For CC we found opposite modulation in ScAT and PtAT for the gene expression of TLR4, Caspase-1 (cachectic group) and for NF-κB p50, NF-κB p65, IL-1β. CD36, expression was decreased in both depots while that of NLRP3 and IL-18 was higher in both tissues, as compared with controls and weight stable patients (WSC). Caspase-1 basal protein levels in the ScAT culture supernatant were higher in WSC and (weight stable patients) CC, when compared to controls. Basal ScAT explant culture medium IL-1β and IL-18 protein content in ScAT supernatant was decreased in the WSC and CC as compared to CTL explants.

Conclusions

The results demonstrate heterogeneous responses in the activation of genes of the NLRP3 inflammasome pathway in the adipose tissue of patients with cancer cachexia, rendering this pathway a potential target for therapy aiming at decreasing chronic inflammation in cancer.

Associations of NLRP3 and CARD8 gene polymorphisms with alcohol dependence and commonly related psychiatric disorders: a preliminary study

We investigated two functional polymorphisms in NLRP3 inflammasome genes (NLRP3 rs35829419 and CARD8 rs2043211) and their association with alcohol dependence and related anxiety, depression, obsession-compulsion, or aggression in 88 hospitalised alcohol-dependent patients, 99 abstinent alcohol-dependent participants, and 94 controls, all male Caucasian. Alcohol dependence-related psychiatric disorders were assessed with the Zung Depression and Anxiety scale, Buss-Durkee Hostility Inventory, Alcohol Use Disorders Identification Test, Brief Social Phobia Scale, Obsessive Compulsive Drinking Scale, and Yale-Brown Obsessive-Compulsive Scale. For genotyping we used the allele-specific quantitative polymerase chain reaction-based methods. The three groups differed significantly in CARD8 rs2043211 distribution (P=0.049; chi-squared=9.557; df=4). The NLPR3 rs35829419 polymorphism was not significantly associated with alcohol dependence. In hospitalised alcohol-dependent patients the investigated polymorphisms were not associated with scores indicating alcohol consumption or comorbid symptoms. In abstinent alcohol-dependent subjects homozygotes for the polymorphic CARD8 allele presented with the highest scores on the Zung Anxiety Scale (p=0.048; df=2; F=3.140). Among controls, CARD8 genotype was associated with high scores on the Obsessive Compulsive Drinking Scale (P=0.027; df=2; F=3.744). In conclusion, our results reveal that CARD8 rs2043211 may play some role in susceptibility to alcohol dependence, expression of anxiety symptoms in abstinent alcohol-dependent subjects, and in obsessive compulsive drinking in healthy controls. However, further studies with larger cohorts are required to confirm these preliminary findings.

Evaluation of NLRP3 (rs10754558) and PTPN22 (1858C/T) (rs2476601) Functional Polymorphisms in Psoriasis Susceptibility in Egypt

BACKGROUND

Psoriasis is a complex autoimmune multifactorial disease induced by interaction of environmental and genetic factors. This research aimed to clarify the association of NLRP3 (rs10754558) and PTPN22 (1858C/T) (rs2476601) polymorphisms with susceptibility to psoriasis.

METHODS

This case-control study involved 150 patients diagnosed with psoriasis and 100 age- and gender-matched apparently healthy individuals. NLRP3 (rs10754558) polymorphism was done by real time PCR and PTPN22 1858C/T (rs2476601) genotype was identified by tetra-primer amplification refractory mutation system-polymerase chain reaction (PCR) method.

RESULTS

The genotypes distribution of NLRP3 (rs10754558) were significantly associated with psoriasis (p<0.0001). Whereas for PTPN22 (1858C/T) (rs2476601), no significance was found (p=0.09). NLRP3 (rs10754558) GC genotype revealed a significant association with psoriasis (p<0.0001), mainly among male (p=0.004) patients with mild psoriasis (p=0.001) and affected extremities (p=0.0001).

CONCLUSION

We can conclude that the NLRP3 (rs10754558) GC genotype may play a role in psoriasis susceptibility among male Egyptian populations with affected extremities. Future studies must evaluate its role in the prevention or the treatment of psoriasis.

Genetic Polymorphisms of NLRP3 (rs4612666) and CARD8 (rs2043211) in Periodontitis and Cardiovascular Diseases

BACKGROUND

The existing data show that inflammasomes play a role in periodontal disease pathogenesis. However, their role in the pathogenesis of periodontitis and coronary heart disease remains unclear. This study had the objective of assessing NLRP3 (rs4612666) and CARD8 (rs2043211) gene polymorphisms in dental plaque and blood of generalized chronic periodontitis (CP) patients in the presence and absence of coronary heart disease (CHD).

METHODS

A total of 70 subjects were divided into two groups, including CP and CP + CHD subjects. Demographic variables, periodontal, and cardiac parameters were recorded from both groups. Subgingival plaque and blood samples were obtained from both groups and were subjected to further molecular analysis for NLRP3 (rs4612666) and CARD8 (rs2043211) expression and allele change using conventional polymerase chain reaction (PCR) and gene sequencing (Sanger's method).

RESULTS

Amongst the demographic variables, age, and monthly income were statistically significant between the two groups. Plaque index (PI), clinical attachment level (CAL), high-density lipoprotein (HDL), and low density-lipoprotein (LDL) exhibited statistically significant levels between the two groups. NLRP3 (rs4612666) and CARD8 (rs2043211) genes showed a statistically significant association of allele change (frequency) among the groups. In general, when all of the parameters were compared to the allele change of the genes, statistically significant relationships were found between the two groups.

CONCLUSIONS

The present study expressed an allele change of the investigated genes which could profoundly affect the pathobiology of the two diseases under investigation.

CARD8 SNP rs11672725 Identified as a Potential Genetic Variant for Adult-Onset Still's Disease

Adult-onset Still's disease (AOSD), an autoinflammatory disorder, is related to the dysregulation of NLR3-containing a pyrin domain (NLRP3)-inflammasome signaling. We aimed to investigate the associations of genetic polymorphisms of NLRP3-inflammasome signaling with AOSD susceptibility and outcome and to examine their functional property. Fifty-three candidate single-nucleotide polymorphisms (SNPs) involved in NLRP3-inflammasome response were genotyped using Sequenom MassArray on the samples from 66 AOSD patients and 128 healthy controls. The significant SNPs were validated by direct sequencing using a TaqMan SNP analyzer. Serum levels of associated gene products were examined by ELISA. One SNP rs11672725 of CARD8 gene was identified to be significantly associated with AOSD susceptibility by using MassArray and subsequent replication validation (p = 3.57 × 10^-7; odds ratio 3.02). Functional assays showed that serum CARD8 levels were significantly lower in AOSD patients (median, 10,524.6 pg/mL) compared to controls (13,964.1 pg/mL, p = 0.005), while levels of caspase-1, IL-1β and IL-18 were significantly higher in patients (107.1 pg/mL, 2.1 pg/mL, and 1495.8 pg/mL, respectively) than those in controls (99.0 pg/mL, 1.0 pg/mL, and 141.4 pg/mL, respectively). Patients carrying rs11672725CC genotype had significantly higher serum caspase-1 and IL-18 levels (121.3 pg/mL and 1748.6 pg/mL) compared to those with CT/TT genotypes (72.6 pg/mL, p = 0.019 and 609.3 pg/mL, p = 0.046). A higher proportion of patients with rs11672725CC genotype had a systemic pattern of disease outcome, which was linked to low CARD8 levels. A novel variant, rs11672725, of the CARD8 gene was identified as a potential genetic risk for AOSD. Patients carrying the rs11672725CC genotype and C allele had low CARD8 levels, and were predisposed to a systemic pattern with an elevated expression of inflammasome signaling.

Pro-inflammatory profile of visceral adipose tissue and oxidative stress in severe obese patients carrying the variant rs4612666 C of NLRP3 gene

BACKGROUND

the activation of NLRP3 inflammasome machinery has a central role in obesity-induced inflammation. Genetic studies well support the involvement of functional variants of NLRP3 and its negative regulator, CARD8, in the pathogenesis of complex diseases with an inflammatory background. We have investigated the influence of NLRP3 (rs4612666; rs10754558) and CARD8 (rs204321) genetic variants in both the inflammatory status of visceral adipose tissue (VAT) from patients with severe obesity and in the systemic oxidative stress before and after sleevegastrectomy (SLG).

METHODS

23 consecutive severe obese patients candidate to SLG were enrolled in the study. Visceral adipose tissue (VAT) biopsies, obtained during SLG, were used to evaluate the expression of NLRP3, IL-1β, IL-6, and MCP-1 by real-time RT-PCR. DNA was extracted from peripheral blood lymphocytes and genotyped by RFLP analysis. Before and 3 months after SLG, all patients underwent the assessment of oxidative stress, biochemical parameters, and body-composition as measured by bioelectrical impedance analysis (BIA).

RESULTS

Increased expression of NLRP3, IL-6, IL-1β, and MCP-1 mRNA was observed in VAT of rs4612666 C variant carriers, in which higher oxidative stress was also detected as compared to non-carrier individuals. In all patients, oxidative stress, biochemical and BIA parameters improved after SLG, regardless of genotype. No significant correlations were found with the other genetic variants.

CONCLUSIONS

Our results suggest that the NLRP3 rs4612666 C variant may promote a worse pro-inflammatory-milieu and higher oxidative stress, thus leading patients to a more severe obesity phenotype. A larger study is needed to confirm this assumption and to investigate the impact of the NLRP3 rs4612666 C variant on severe obesity.

Single-Nucleotide Variants in the AIM2 - Absent in Melanoma 2 Gene (rs1103577) Associated With Protection for Tuberculosis

Tuberculosis (TB) remains a serious public health burden worldwide. TB is an infectious disease caused by the Mycobacterium tuberculosis Complex. Innate immune response is critical for controlling mycobacterial infection. NOD-like receptor pyrin domain containing 3/ absent in melanoma 2 (NLRP3/AIM2) inflammasomes are suggested to play an important role in TB. NLRP3/AIM2 mediate the release of pro-inflammatory cytokines IL-1β and IL-18 to control M. tuberculosis infection. Variants of genes involved in inflammasomes may contribute to elucidation of host immune responses to TB infection. The present study evaluated single-nucleotide variants (SNVs) in inflammasome genes AIM2 (rs1103577), CARD8 (rs2009373), and CTSB (rs1692816) in 401 patients with pulmonary TB (PTB), 133 patients with extrapulmonary TB (EPTB), and 366 healthy control (HC) subjects with no history of TB residing in the Amazonas state. Quantitative Real Time PCR was performed for allelic discrimination. The SNV of AIM2 (rs1103577) is associated with protection for PTB (padj: 0.033, ORadj: 0.69, 95% CI: 0.49-0.97). CTSB (rs1692816) is associated with reduced risk for EPTB when compared with PTB (padj: 0.034, ORadj: 0.50, 95% CI: 0.27-0.94). Serum IL-1β concentrations were higher in patients with PTB than those in HCs (p = 0,0003). The SNV rs1103577 of AIM2 appeared to influence IL-1β release. In a dominant model, individuals with the CC genotype (mean 3.78 ± SD 0.81) appeared to have a higher level of IL-1β compared to carriers of the T allele (mean 3.45 ± SD 0.84) among the patients with PTB (p = 0,0040). We found that SNVs of AIM2 and CTSB were associated with TB, and the mechanisms involved in this process require further study.

Biological functions of NLRP3 inflammasome: A therapeutic target in inflammatory bowel disease

Cases of inflammatory bowel disease (IBD), a debilitating intestinal disorder with complex pathological mechanisms, have been increasing in recent years, straining the capacity of healthcare systems. Thus, novel therapeutic targets and innovative agents must be developed. Notably, the NLRP3 inflammasome is upregulated in patients with IBD and/or in animal experimental models. As an innate immune supramolecular assembly, the NLRP3 inflammasome is persistently activated during the pathogenesis of IBD by multiple stimuli. Moreover, this protein complex regulates pro-inflammatory cytokines. Thus, targeting this multiprotein oligomer may offer a feasible way to relieve IBD symptoms and improve clinical outcomes. The mechanisms by which the NLRP3 inflammasome is activated, its role in IBD pathogenesis, and the drugs administered to target this protein complex are reviewed herein. This review establishes that the use of inflammasome-targeting drugs are effective for IBD treatment. Moreover, this review suggests that the value and potential of naturally sourced or derived medicines for IBD treatment must be recognized and appreciated.

Pharmacogenetics-Based Preliminary Algorithm to Predict the Incidence of Infection in Patients Receiving Cytotoxic Chemotherapy for Hematological Malignancies: A Discovery Cohort

Introduction: Infections in hematological cancer patients are common and usually life-threatening; avoiding them could decrease morbidity, mortality, and cost. Genes associated with antineoplastics’ pharmacokinetics or with the immune/inflammatory response could explain variability in infection occurrence.

Objective: To build a pharmacogenetic-based algorithm to predict the incidence of infections in patients undergoing cytotoxic chemotherapy.

Methods: Prospective cohort study in adult patients receiving cytotoxic chemotherapy to treat leukemia, lymphoma, or myeloma in two hospitals in Santiago, Chile. We constructed the predictive model using logistic regression. We assessed thirteen genetic polymorphisms (including nine pharmacokinetic—related genes and four inflammatory response-related genes) and sociodemographic/clinical variables to be incorporated into the model. The model’s calibration and discrimination were used to compare models; they were assessed by the Hosmer-Lemeshow goodness-of-fit test and area under the ROC curve, respectively, in association with Pseudo-R².

Results: We analyzed 203 chemotherapy cycles in 50 patients (47.8 ± 16.1 years; 56% women), including 13 (26%) with acute lymphoblastic and 12 (24%) with myeloblastic leukemia.

Pharmacokinetics-related polymorphisms incorporated into the model were CYP3A4 rs2242480C>T and OAT4 rs11231809T>A. Immune/inflammatory response-related polymorphisms were TLR2 rs4696480T>A and IL-6 rs1800796C>G. Clinical/demographic variables incorporated into the model were chemotherapy type and cycle, diagnosis, days in neutropenia, age, and sex. The Pseudo-R² was 0.56, the p-value of the Hosmer-Lemeshow test was 0.98, showing good goodness-of-fit, and the area under the ROC curve was 0.93, showing good diagnostic accuracy.

Conclusions: Genetics can help to predict infections in patients undergoing chemotherapy. This algorithm should be validated and could be used to save lives, decrease economic costs, and optimize limited health resources.

CARD8 polymorphism rs2043211 protects against noise-induced hearing loss by causing the dysfunction of CARD8 protein

Inflammation is a complicated process and is considered to be responsible for the development of noise-induced hearing loss (NIHL). CARD8 is an important component of inflammasome that has been implicated in inflammation. To decide the relationship between the polymorphisms of CARD8 gene and NIHL risk and deduce the potential mechanism, three SNPs (rs2043211, rs1062808, and rs12459322) were genotyped in a Chinese population consisting of 610 NIHL cases and 612 normal hearing controls. The possible impacts of SNPs on CARD8 structure and function were assessed using a variety of bioinformatics tools. Plasmids expressing wild-type and/or mutated CARD8 were transfected into HEK293 cells to verify the effect of SNPs on CARD8 protein expression level by western blot. The results revealed that rs2043211 AA genotype and A allele were associated with decreased risk of NIHL. Stratified analysis found that the male, drinking and exposed to noise ≥ 92 dB, subjects harboring rs2043211 A allele had a low risk of NIHL. The haplotype AGG (rs2043211-rs1062808-rs12459322) was significantly associated with a decreased risk of NIHL. SNP rs2043211 was predicted to be deleterious and affects CARD8 protein structure and stability. Furthermore, the functional experiment showed the mutant CARD8 could significantly decrease the CARD8 protein expression level. This study confirms that rs2043211 A allele may reduce NIHL risk by causing the loss of PPI combined with the decreased CARD8 expression level leading to CARD8 functional changes, and it may be one valuable genetic biomarker of NIHL susceptibility for Chinese noise-exposed workers.

Association between inflammasome-related polymorphisms and psoriatic arthritis

Objective: Psoriatic arthritis (PsA) is a heterogeneous inflammatory disease associated with psoriasis. Underlying genetic factors are considered important for disease expression and prognosis of PsA. Interleukin-1β-regulating protein complexes called inflammasomes are associated with several inflammatory diseases, e.g. rheumatoid arthritis and psoriasis. The aim was to determine whether inflammasome-related genetic variation is associated with PsA susceptibility or different disease phenotypes.Method: DNA from 724 patients with PsA and 587 population-based controls from northern Sweden was analysed for single-nucleotide polymorphisms in NLRP3-Q750K (rs35829419), NLRP3 (rs10733113), CARD8-C10X (rs2043211), NLRP1 (rs8079034), and NLRP1 (rs878329).Results: Significant associations were found with the genotype AA (vs AT+TT) of rs2043211 for PsA patients compared with controls [odds ratio (OR), 95% confidence interval (CI) 1.32 (1.05-1.65), p = 0.016]; and between the C-allele of rs878329 and axial involvement of PsA [OR (95% CI) 1.37 (1.02-1.84), p = 0.035], the T-allele of rs8079034 with prescription of conventional synthetic disease-modifying anti-rheumatic drugs [OR (95% CI) 1.76 (1.23-2.53), p = 0.0020], the G-allele of rs10733113 and patients with a skin disease with early onset [OR (95% CI) 1.58 (1.13-2.21), p = 0.007], and the C-allele of rs35829419 and a destructive/deforming disease [OR (95% CI) 1.63 (1.04-2.55), p = 0.030].Conclusions: This study is the first to show an association with a genetic polymorphism in an inflammasome-related gene, CARD8-C10X (rs2043211), in patients with PsA. Associations between different phenotypes of PsA and different polymorphisms of the inflammasome genes were also found. Our results indicate the involvement of inflammasome genes in the pathogenesis and disease expression of PsA.

Expression of CARD8 in human atherosclerosis and its regulation of inflammatory proteins in human endothelial cells

The Caspase activation and recruitment domain 8 (CARD8) protein is a component of innate immunity and overexpression of CARD8 mRNA was previously identified in atherosclerosis. However, very little is known about the regulation of CARD8 in endothelial cells and atherosclerosis. The aim of this study was to investigate CARD8 in the regulation of cytokine and chemokine expression in endothelial cells. Sections of human atherosclerotic lesions and non-atherosclerotic arteries were immunostained for CARD8 protein. Expression of CARD8 was correlated to mediators of inflammation in atherosclerotic lesions using Biobank of Karolinska Endarterectomies microarray data. The CARD8 mRNA was knocked-down in human umbilical vein endothelial cells (HUVECs) in vitro, followed by quantitative RT-PCR analysis and OLINK Proteomics. Endothelial and smooth muscle cells in arterial tissue expressed CARD8 and CARD8 correlated with vWF, CD163 and the expression of inflammatory genes, such as CXCL1, CXCL6 and PDGF-A in plaque. Knock-down of CARD8 in HUVECs significantly altered proteins involved in inflammatory response, such as CXCL1, CXCL6, PDGF-A, MCP-1 and IL-6. The present study suggest that CARD8 regulate the expression of cytokines and chemokines in endothelial cells and atherosclerotic lesions, suggesting that CARD8 plays a significant role in endothelial activation.

IL-6 -572C>G and CARD8 304T>A Genetic Polymorphisms are Associated with the Absolute Neutrophil Count in Patients with Hematological Malignancies Under Chemotherapy: An Application of Multilevel Models to a Preliminary Pharmacogenetic Study

Purpose

Neutropenia is a common event in patients undergoing cytotoxic chemotherapy for the treatment of a hematological malignancy. Some polymorphisms, as IL-6 -572C>G (rs1800796), IL-1β -31 G>A (rs1143627), and CARD8 304T>A (rs2043211), in genes related to the inflammatory process, could affect the level of absolute neutrophil count (ANC) after chemotherapy. Since an efficient inflammatory process enhances neutrophil survival, we hypothesize that these polymorphisms are associated with ANC.

Patients and Methods

We carried out a prospective cohort study in two hospitals in Santiago, Chile. The patients included were adults diagnosed with acute myeloblastic leukemia, acute lymphoblastic leukemia, or non-Hodgkin's lymphoma, undergoing cytotoxic chemotherapy. We use a multilevel linear regression model to test our hypothesis. The best model was selected using the Akaike's information criterion (AIC).

Results

We analyzed 1726 hemograms and ANCs from 172 hospitalizations from 32 patients. The results show that CC and CG genotypes of IL-6 -572 C>G polymorphism are associated with higher ANCs compared with the GG genotype (Ln (ANC) ~ 0.81 IC95% 0.02-1.55). Similarly, TT and AT genotypes of CARD8 304T>A polymorphism were related to higher ANCs compared with AA (Ln (ANC) ~ 0.95 IC95% 0.02-1.82). IL-1β genetic polymorphism had no statistically significant association with ANC.

Conclusion

IL-6 rs1800796 -572C>G and CARD8 rs2043211 304T>A polymorphisms are associated with the absolute neutrophil count in patients undergoing cytotoxic chemotherapy for treatment of hematological malignancies. Our findings might be useful to improve the safety of chemotherapy through predictive ANC models.

Fungal cutaneous microbiome and host determinants in preterm and term neonates

BACKGROUND

The neonatal cutaneous mycobiome has not been characterized in preterm infants. Invasive fungal infections in preterm neonates are associated with high mortality. The immaturity of the preterm skin predisposes neonates to invasive infection by skin colonizers. We report the clinical and host determinants that influence the skin mycobiome.

METHODS

Skin swabs from the antecubital fossa, forehead, and gluteal region of 15 preterm and 15 term neonates were obtained during the first 5 weeks of life. The mycobiome was sequenced using the conserved pan-fungal ITS2 region. Blood samples were used to genotype immune modulating genes. Clinical metadata was collected to determine the clinical predictors of the abundance and diversity of the skin mycobiome.

RESULTS

The neonatal mycobiome is characterized by few taxa. Alpha diversity of the mycobiome is influenced by antibiotic exposure, the forehead body site, and the neonatal intensive care unit (NICU) environment. Beta diversity varies with mode of delivery, diet, and body site. The host determinants of the cutaneous microbiome include single-nucleotide polymorphisms in TLR4, NLRP3,CARD8, and NOD2.

CONCLUSION

The neonatal cutaneous mycobiome is composed of few genera and is influenced by clinical factors and host genetics, the understanding of which will inform preventive strategies against invasive fungal infections.

Inflammasome inhibition under physiological and pharmacological conditions

Inflammasomes are key regulators of the host response against microbial pathogens, in addition to limiting aberrant responses to sterile insults, as mediated by environmental agents such as toxins or nanoparticles, and also by endogenous danger signals such as monosodium urate, ATP and amyloid-β. To date at least six different inflammasome signalling platforms have been reported (Bauernfeind & Hornung, EMBO Mol Med. 2013;5:814-26; Broz & Dixit, Nat Rev Immunol. 2016;16:407). This review focuses on the complex molecular machinery involved in activation and regulation of the best characterised inflammasome, NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3), and the development of molecular agents to modulate NLRP3 inflammasome function. Activation of the NLRP3 inflammasome induces inflammation via secretion of interleukin-1β (IL-1β) and interleukin-18 (IL-18) proinflammatory cytokines, with orchestration of pyroptotic cell death, to eliminate invading microbial pathogens. This field has gradually moved from an emphasis on monogenic autoinflammatory conditions, such as cryopyrin-associated periodic syndromes (CAPS), to the broad spectrum of innate immune-mediated disease. NLRP3 inflammasome activation is also linked to a range of common disorders in humans including type 2 diabetes (Krainer et al., J Autoimmun. 2020:102421), cystic fibrosis (Scambler et al., eLife. 2019;8), myocardial infarction, Parkinson's disease, Alzheimer's disease (Savic et al., Nat Rev Rheumatol. 2020:1-16) and cancers such as mesotheliomas and gliomas (Moossavi et al., Mol Cancer. 2018;17:158). We describe how laboratory-based assessment of NLRP3 inflammasome activation is emerging as an integral part of the clinical evaluation and treatment of a range of undifferentiated systemic autoinflammatory disorders (uSAID) (Harrison et al., JCI Insight. 2016;1), where a DNA-based diagnosis has not been possible. In addition, this review summarises the current literature on physiological inhibitors and features various pharmacological approaches that are currently being developed, with potential for clinical translation in autoinflammatory and immune-mediated conditions. We discuss the possibilities of rational drug design, based on detailed structural analyses, and some of the challenges in transferring exciting preliminary results from trials of small-molecule inhibitors of the NLRP3 inflammasome, in animal models of disease, to the clinical situation in human pathology.

Multifactorial Activation of NLRP3 Inflammasome: Relevance for a Precision Approach to Atherosclerotic Cardiovascular Risk and Disease

Chronic low-grade inflammation, through the specific activation of the NACHT leucine-rich repeat- and PYD-containing (NLRP)3 inflammasome-interleukin (IL)-1β pathway, is an important contributor to the development of atherosclerotic cardiovascular disease (ASCVD), being triggered by intracellular cholesterol accumulation within cells. Within this pathological context, this complex pathway is activated by a number of factors, such as unhealthy nutrition, altered gut and oral microbiota, and elevated cholesterol itself. Moreover, evidence from autoinflammatory diseases, like psoriasis and others, which are also associated with higher cardiovascular disease (CVD) risk, suggests that variants of NLRP3 pathway-related genes (like NLRP3 itself, caspase recruitment domain-containing protein (CARD)8, caspase-1 and IL-1β) may carry gain-of-function mutations leading, in some individuals, to a constitutive pro-inflammatory pattern. Indeed, some reports have recently associated the presence of specific single nucleotide polymorphisms (SNPs) on such genes with greater ASCVD prevalence. Based on these observations, a potential effective strategy in this context may be the identification of carriers of these NLRP3-related SNPs, to generate a genomic score, potentially useful for a better CVD risk prediction, and, possibly, for personalized therapeutic approaches targeted to the NLRP3-IL-1β pathway.

Focus on the Role of NLRP3 Inflammasome in Diseases

Inflammation is a protective reaction activated in response to detrimental stimuli, such as dead cells, irritants or pathogens, by the evolutionarily conserved immune system and is regulated by the host. The inflammasomes are recognized as innate immune system sensors and receptors that manage the activation of caspase-1 and stimulate inflammation response. They have been associated with several inflammatory disorders. The NLRP3 inflammasome is the most well characterized. It is so called because NLRP3 belongs to the family of nucleotide-binding and oligomerization domain-like receptors (NLRs). Recent evidence has greatly improved our understanding of the mechanisms by which the NLRP3 inflammasome is activated. Additionally, increasing data in animal models, supported by human studies, strongly implicate the involvement of the inflammasome in the initiation or progression of disorders with a high impact on public health, such as metabolic pathologies (obesity, type 2 diabetes, atherosclerosis), cardiovascular diseases (ischemic and non-ischemic heart disease), inflammatory issues (liver diseases, inflammatory bowel diseases, gut microbiome, rheumatoid arthritis) and neurologic disorders (Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, amyotrophic lateral sclerosis and other neurological disorders), compared to other molecular platforms. This review will provide a focus on the available knowledge about the NLRP3 inflammasome role in these pathologies and describe the balance between the activation of the harmful and beneficial inflammasome so that new therapies can be created for patients with these diseases.

Association of CARD8 Activating Polymorphism With Bone Erosion in Cholesteatoma Patients

OBJECTIVES

We compared the incidence of polymorphisms activating the NLRP3 inflammasome between controls and patients with cholesteatoma and its potential association with bone erosion in patients with cholesteatoma.

METHODS

This is a case-control study assessing the mutation rates in genes of interest in patients with and without cholesteatoma. A total of 133 saliva samples from control (n = 65) and cholesteatoma (n = 68) patients were collected for DNA extraction. Caspase recruitment domain family member 8 (CARD8) (AA: homozygous wild type, AT: heterozygous, TT: homozygous mutant polymorphism) and NLRP3 (CC: homozygous wild type, CA: heterozygous, AA: homozygous mutant) polymorphisms were analyzed with TaqMan single-nucleotide polymorphism (SNP) quantitative polymerase chain reaction (ThermoFisher Scientific, Waltham, MA). Mutation status was correlated with a novel bone erosion scoring model developed as a part of this study. Summary statistics, including frequencies (%) and median (Q1, Q3) were used to describe the sample.

RESULTS

The presence of CARD8 and NLRP3 homozygous wild-type polymorphisms were generally similar for the control and cholesteatoma patient groups. CARD8 homozygous TT polymorphisms were an exception, occurring more frequently in patients who developed a cholesteatoma compared to the control group (29% vs. 10%, P = .009). Those patients with CARD8 homozygous TT polymorphism had higher median scores of bone erosion as compared to subjects with nonhomozygous mutant genotypes (median [interquartile range]: 4.0 [3.0, 5.5] vs. 2.5 [1.0, 3.5], P = .0142).

CONCLUSION

Cholesteatoma patients have a significant, twofold higher incidence of CARD8 homozygous TT polymorphism. Furthermore, cholesteatoma patients with this homozygous polymorphism had greater bone erosion rates than controls. These findings suggest that genetic mutations may increase host susceptibility to cholesteatomas. Specifically, the CARD8 TT polymorphism may influence the severity of cholesteatoma-induced bone erosion.

LEVEL OF EVIDENCE

3B.

Polymorphism of nucleotide binding domain-like receptor protein 3 (NLRP3) increases susceptibility of total urinary arsenic to renal cell carcinoma

Our study showed that total urinary arsenic concentrations were positively correlated with renal cell carcinoma (RCC). Chronic inflammation is a key player in the development of RCC. This study explored the association between nucleotide-binding domain-like receptor protein 3 (NLRP3) genotypes and the development of RCC. We also investigated whether any of the NLRP3 genotypes modified the risk between arsenic and RCC. We recruited 350 RCC patients and 700 age-sex matched controls. RCC was confirmed by pathological assessment following surgical resection or image-guided biopsy of a renal tumor. Fifteen sites of NLRP3 gene polymorphisms were identified using the Agena Bioscience MassARRAY platform. The concentrations of the urinary arsenic species were determined by HPLC-HG-AAS. There was a significant dose-dependent association between arsenic and RCC. In addition, six of thirteen NLRP3 alleles, including rs12239046 C, rs10925025 G, rs1539019 C, rs10925026 A, rs10157379 T, and rs12143966 A, had increased odds ratios (ORs) for RCC than other NLRP3 alleles. Among these sites, we found the novel haplotype of five tag-SNPs (C-A-A-A-A) was significantly related to RCC, the OR and 95% confidence interval was 1.44 (1.08–1.92). Furthermore, participants with high total urinary arsenic levels and the NLRP3 rs1539019 C allele had significantly multiplicative and additive interactions for the risk of RCC (p _interaction = 0.012). This study is the first to identify the modified effects of NLRP3 risk alleles involved in the association between arsenic and RCC risk in a population with low arsenic exposure.

Relationship of CARD8 Gene Polymorphisms with Susceptibility to Ankylosing Spondylitis: A Case-Control Study

BACKGROUND The aim of this case-control study was to evaluate the correlation of caspase recruitment domain-containing protein 8 (CARD8) gene rs2043211 (exon) and rs7253718 (intron) polymorphisms with the susceptibility of ankylosing spondylitis (AS) in the Chinese Han population. MATERIAL AND METHODS CARD8 polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 118 AS patients and 122 healthy persons. Linkage disequilibrium (LD) and haplotype analysis were carried out using Haploview software. Distribution differences of genotypes, alleles and haplotypes between the case and control groups were tested by chi-square test. Relative risk of AS was expressed by odds ratios (ORs) and 95% confidence intervals (CIs). Logistic regression analysis was used to adjust the results of association by clinical parameters. RESULTS For rs2043211, distribution of variant allele T was obviously different between AS patients and healthy controls (P=0.046). It indicated that T allele might increase the susceptibility of AS (OR=1.441, 95%CI=1.006-2.065). Adjusted by clinical characteristics, the significance of difference was slightly decreased (P=0.050, OR=1.439, 95%CI=0.999-2.072). Strong LD existed between rs2043211 and rs7253718 polymorphisms, and rs2043211T-rs7253718G haplotype was significantly associated with increased AS susceptibility (OR=1.787, 95%CI=1.165-2.740). In subgroup analysis, we found that the TT genotype and T allele of rs2043211 significantly increased the risk of AS in males (TT versus AA: OR=2.554, 95%CI=1.079-6.049; T versus A: OR=1.661, 95%CI=1.067-2.586), but not females. CONCLUSIONS CARD8 polymorphisms are likely to be associated with the elevated susceptibility of AS. Present results should be confirmed in the future studies.

Association of NLRP3 and CARD8 Inflammasome Polymorphisms With Aseptic Loosening After Primary Total Hip Arthroplasty

Our aim was to investigate the association of inflammasome polymorphisms NLRP3 rs35829419 (p. Q705K) and CARD8 rs2043211 (p. C10X) with aseptic loosening of total hip endoprostheses. We asked whether patients with the loosening of total hip arthroplasty earlier than 15 years after primary implantation had a higher proportion of the polymorphisms Q705K and C10X in comparison to subjects without loosening. A retrospective case-control study compared 36 patients with total hip endoprosthesis loosening earlier than 15 years after primary implantation and 51 control subjects with unloosened total hip endoprostheses, matched for gender, age, and follow-up period. Buccal mucosa samples were used for genomic DNA analysis and genotyped for NLRP3 rs35829419 and CARD8 rs2043211 using a fluorescence-based competitive allele-specific real-time polymerase chain reaction. The proportion of subjects with both wild-type NLRP3 and CARD8 (i.e., without Q705K or C10X) was considerably higher in the control group when compared with patients with early total hip arthroplasty loosening (49% vs. 28%; p = 0.05). After adjustment for gender, age, and follow-up, patients with combined wild type of both NLRP3 and CARD8 had significantly smaller odds for early implant loosening (odds ratio 0.33, p = 0.02). Investigated polymorphisms may influence several inflammatory pathways and contribute to the loosening of artificial implants with potential clinical significance for the appropriate selection of patients and endoprostheses when planning elective total hip arthroplasty. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:417-421, 2020.

Inhibition of PRMT5 Attenuates Oxidative Stress-Induced Pyroptosis via Activation of the Nrf2/HO-1 Signal Pathway in a Mouse Model of Renal Ischemia-Reperfusion Injury

Background

Extensive evidence has demonstrated that oxidative stress, pyroptosis, and proinflammatory programmed cell death are related to renal ischemia/reperfusion (I/R) injury. However, the underlying mechanism remains to be illustrated. Protein arginine methylation transferase 5 (PRMT5), which mediates arginine methylation involved in the regulation of epigenetics, exhibits a variety of biological functions and essential roles in diseases. The present study investigated the role of PRMT5 in oxidative stress and pyroptosis induced by I/R injury in a mouse model and in a hypoxia/reoxygenation (H/R) model of HK-2 cells.

Methods

C57 mice were used as an animal model. All mice underwent right nephrectomy, and the left renal pedicles were either clamped or not. Renal I/R injury was induced by ligating the left renal pedicle for 30 min followed by reperfusion for 24 h. HK-2 cells were exposed to normal conditions or stimulation through H/R. EPZ015666(EPZ)—a selective potent chemical inhibitor—and small interfering RNA (siRNA) were administered to suppress the function and expression of PRMT5. The levels of urea nitrogen and creatinine in the serum and renal tissue injury were assessed. Immunohistochemistry, western blotting, and reverse transcription-polymerase chain reaction were used to evaluate pyroptosis-related proteins including nod-like receptor protein-3, ASC, caspase-1, caspase-11, GSDMD-N, and interleukin-1β. Cell apoptosis and cell viability were detected through flow cytometry, and the levels of reactive oxygen species (ROS) and hydrogen peroxide (H₂O₂) were measured. Ki-67 was used to assess the proliferation of renal tubular epithelium. In addition, the activity of malondialdehyde and superoxide dismutase was determined.

Results

I/R or H/R induced an increase in the expression of PRMT5. Inhibition of PRMT5 by EPZ alleviated oxidative stress and I/R- or H/R-induced pyroptosis. In renal tissue, the application of EPZ promoted the proliferation of tubular epithelium. In addition, H/R-induced pyroptosis in HK-2 cells was dependent on oxidative stress in vitro. Administration of either EPZ or siRNA led to decreased expression of pyroptosis-related proteins. Inhibition of PRMT5 also attenuated the I/R- or H/R-induced oxidative stress in vivo and in HK-2 cells, respectively. It also resulted in a distinct decrease in the levels of malondialdehyde and H₂O₂, and an apparent increase in superoxide dismutase activity in mouse renal tissue. Moreover, it led to a significant decrease in the levels of ROS and H₂O₂ in HK-2 cells. When activated, NF-E2-related factor/heme oxygenase-1 (Nrf2/HO-1)—a key regulator of various cytoprotective proteins that withstand oxidative damage—can decrease the generation of ROS. Nrf2/HO-1 was downregulated during I/R in tissues and H/R in HK-2 cells, and this effect was reversed by the PRMT5 inhibitor. Furthermore, the expressions of Nrf2 and HO-1 proteins were markedly upregulated by EPZ or siRNA against PRMT5.

Conclusion

PRMT5 is involved in ischemia- and hypoxia-induced oxidative stress and pyroptosis in vitro and in vivo. Inhibition of PRMT5 may ameliorate renal I/R injury by suppressing oxidative stress and pyroptosis via the activation of the Nrf2/HO-1 pathway, as well as promoting the proliferation of tubular epithelium. Therefore, PRMT5 may be a promising therapeutic target.

Antagonistic role of IL-1ß and NLRP3/IL-18 genetics in chronic HIV-1 infection

Host genetics affects both susceptibility and progression of HIV-1 infection. NLRP3 inflammasome provides a first-line defense in viral infections, and, accordingly, gain-of-function variants in NLRP3 have been associated with protection against HIV-1. Despite antiretroviral treatment (ART), HIV-infected patients continue to present systemic inflammation with a heterogeneous prognosis. As NLRP3 inflammasome is involved in several chronic diseases by amplifying "sterile" inflammation, its role in chronic phase of HIV infection has been postulated. Little is known about inflammasome genetics in HIV-infected patients and whether it may play a role in the different clinical outcomes. Therefore, we questioned whether NLRP3 inflammasome genetics could affect the clinical course of HIV-1 infection as it does in host/virus interaction. For this purpose, we analyzed selected single nucleotide polymorphisms (SNPs) in ART-treated HIV-infected patients (n = 300), in Long Term Non-Progressors/Elite Controllers and progressors (n = 133), and in HIV-infected individuals submitted to dendritic cell (DC)-based immunotherapy (n = 19). SNPs leading to increased activation of NLRP3 inflammasome are beneficial for patients, while SNPs that negatively affect NLRP3 activation or IL-18 production, detrimental. In contrast, gain-of-function variant in IL1B is also detrimental for patients, suggesting that while IL-1ß possible contributes to immune exhaustion, the axis NLRP3-inflammasome/IL-18 could act positively in chronic infection. Functional assays supported genetic results: NLRP3 variants associated with good quality HIV+ DC, and IL1B -511C > T with a poor one. Loss-of-function SNPs affect HIV+ T cells proliferation. These findings proposed for the first time that NLRP3 inflammasome, mainly through IL-18, play a protective role in chronic HIV infection.

Electroacupuncture ameliorates cardiopulmonary bypass induced apoptosis in lung via ROS/Nrf2/NLRP3 inflammasome pathway

AIMS

Electroacupuncture (EAc) has a pulmonary protective effect during cardiopulmonary bypass (CPB), but its molecular mechanisms including inflammasome activation signaling pathways remains unclear.

MATERIALS AND METHODS

Male Sprague Dawley rats were divided into control, CPB + EAc and CPB groups. Lung injury model was developed by CPB treatment and EAc (2/100 Hz) was carried out before CPB in the CPB + EAc group. Lung tissues were collected at two time points (0.5 h; 2 h) to determine cytokines release by ELISA kits, and protein expressions by Western blot. Serum collected at two time points (0.5 h; 2 h) from CPB and CPB + EAc treated groups were used in NR8383 cells to confirm the effect of EAc.

KEY FINDINGS

CPB significantly increased the inflammatory mediators, histological damage and expression of inflammasome related protein and apoptosis, when compared with control group. The level of tumor necrosis factor-α(TNF-α), interleukin (IL)-18 and IL-1β in the CPB + EAc treated group was significantly decreased along with histological changes compared to CPB. Moreover, EAc inhibited the activation of Nod like receptor protein-3 (NLRP3) inflammasome complex, caspase-8 and activated NF-E2-related factor 2 (p-Nrf2). In addition, serum from the CPB + EAc group prevented CPB induced activation of inflammasome and related mediators, reducing ROS generation and apoptosis in NR8383 macrophages.

SIGNIFICANCE

These findings indicate that EAc had a critical anti-apoptotic role by suppression of ROS/Nrf2/NLRP3 inflammasome pathway. EAc might be a possible therapeutic treatment for CPB-induced acute lung injury.

Phytochemicals as Novel Therapeutic Strategies for NLRP3 Inflammasome-Related Neurological, Metabolic, and Inflammatory Diseases

Several lines of evidence point out the relevance of nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome as a pivotal player in the pathophysiology of several neurological and psychiatric diseases (i.e., Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS), amyotrophic lateral sclerosis, and major depressive disorder), metabolic disorders (i.e., obesity and type 2 diabetes) and chronic inflammatory diseases (i.e., intestinal inflammation, arthritis, and gout). Intensive research efforts are being made to achieve an integrated view about the pathophysiological role of NLRP3 inflammasome pathways in such disorders. Evidence is also emerging that the pharmacological modulation of NLRP3 inflammasome by phytochemicals could represent a promising molecular target for the therapeutic management of neurological, psychiatric, metabolic, and inflammatory diseases. The present review article has been intended to provide an integrated and critical overview of the available clinical and experimental evidence about the role of NLRP3 inflammasome in the pathophysiology of neurological, psychiatric, metabolic, and inflammatory diseases, including PD, AD, MS, depression, obesity, type 2 diabetes, arthritis, and intestinal inflammation. Special attention has been paid to highlight and critically discuss current scientific evidence on the effects of phytochemicals on NLRP3 inflammasome pathways and their potential in counteracting central neuroinflammation, metabolic alterations, and immune/inflammatory responses in such diseases.

Association between caspase recruitment domain-containing protein 8 rs2043211 polymorphism and cardiovascular disease susceptibility: A systematic review and meta-analysis

Objective:

To verify the association between the caspase recruitment domain-containing protein 8 (CARD8) single nucleotide polymorphism rs2043211 in the CARD8 gene and cardiovascular diseases.

Methods:

A comprehensive search was conducted for related literature in the PubMed, Embase, Cochrane Library, Web of Science, Wanfang Data, and China National Knowledge Infrastructure databases. At last, Six eligible case-control studies were included in this meta-analysis. Crude odds ratios (ORs) and 95% confidence intervals (CI) were calculated to estimate the strength of the association between CARD8 rs2043211 polymorphisms and the susceptibility of cardiovascular diseases.

Results:

For the homozygous model, OR was 1.21 (1.08-1.36, I²=0.0%, P_{heterogeneity}=0.542). For the heterozygous model (AT vs. AA), OR was 1.20 (1.04–1.38, I²=57.2%, P_{heterogeneity}=0.039). For the dominant model, OR was 1.24 (1.14-1.34, I2=38.5%, P_{heterogeneity}=0.149). For the allele model, OR was 0.96 (0.77-1.20, I²=92.7%, P_{heterogeneity}=0.000). For the recessive model, OR was 1.00 (0.91-1.10, I²=48.4%, P_{heterogeneity}=0.085).

Conclusion:

The present study showed that CARD8 rs2043211 polymorphism is associated with cardiovascular diseases.

Dual Role of PTPN22 but Not NLRP3 Inflammasome Polymorphisms in Type 1 Diabetes and Celiac Disease in Children

Genetic polymorphisms in genes coding for inflammasome components nucleotide-binding oligomerization domain leucine rich repeat and pyrin domain-containing protein 3 (NLRP3) and caspase recruitment domain-containing protein 8 (CARD8) have been associated with autoinflammatory and autoimmune diseases. On the other hand several studies suggested that NLRP3 inflammasome contributes to maintenance of gastrointestinal immune homeostasis and that activation of NLRP3 is regulated by protein tyrosine phosphatase non-receptor 22 (PTPN22). PTPN22 polymorphism was implicated in the risk for various autoimmune diseases including type 1 diabetes (T1D) but not for celiac disease (CD). The aim of our study was to evaluate the role of inflammasome related polymorphisms in subjects with either T1D or CD as well as in subjects affected by both diseases. We examined PTPN22 rs2476601 (p.Arg620Trp), NLRP3 rs35829419 (p.Gln705Lys), and CARD8 rs2043211 (p.Cys10Ter) in 66 subjects with coexisting T1D and CD, 65 subjects with T1D who did not develop CD, 67 subjects diagnosed only with CD and 127 healthy unrelated Slovenian individuals. All results were adjusted for clinical characteristic and human leukocyte antigen (HLA) risk. PTPN22 rs2476601 allele was significantly more frequent among subjects with T1D (P_adj = 0.001) and less frequent in subjects with CD (P_adj = 0.039) when compared to controls. In patients with coexisting T1D and CD this variant was significantly less frequent compared to T1D group (P_adj = 0.010). Protective effect on CD development in individuals with T1D was observed only within the low risk HLA group. On the other hand, we found no association of NLRP3 rs35829419 and CARD8 rs2043211 with the development of T1D, CD or both diseases together. In conclusion PTPN22 rs2476601polymorphism was significantly associated with the risk of developing T1D in Slovenian population, while no associations of proinflammatory NLRP3 and CARD8 polymorphisms with T1D and CD were observed. Interestingly, the same PTPN22 variant protected from CD. We hypothesize that this effect may be mediated through the NLRP3 inflammasome activation.

Stressing out the mitochondria: Mechanistic insights into NLRP3 inflammasome activation

Inflammasomes are multimeric protein complexes that induce the cleavage and release of bioactive IL-1β and cause a lytic form of cell death, termed pyroptosis. Due to its diverse triggers, ranging from infectious pathogens and host danger molecules to environmental irritants, the NOD-like receptor protein 3 (NLRP3) inflammasome remains the most widely studied inflammasome to date. Despite intense scrutiny, a universal mechanism for its activation remains elusive, although, recent research has focused on mitochondrial dysfunction or potassium (K⁺ ) efflux as key events. In this review, we give a general overview of NLRP3 inflammasome activation and explore the recently emerging noncanonical and alternative pathways to NLRP3 activation. We highlight the role of the NLRP3 inflammasome in the pathogenesis of metabolic disease that is associated with mitochondrial and oxidative stress. Finally, we interrogate the mechanisms proposed to trigger NLRP3 inflammasome assembly and activation. A greater understanding of how NLRP3 inflammasome activation is triggered may reveal new therapeutic targets for the treatment of inflammatory disease.

Association between Toll-like receptors (TLR) and NOD-like receptor (NLR) polymorphisms and lipid and glucose metabolism

Recent evidences had shown activation of TLR (toll-like receptors) and NLR (nod-like receptors) in response to imbalance in nutrients intake, such as lipid and glucose. The main aim of this study was to investigate possible associations between 11 SNPs in TLR2, TLR4, NLRC4, CARD8 and NEK7 genes and lipid and glucose metabolism. Sample was composed by healthy children and adolescents (n = 158) and adults (n = 115). DNA extraction was obtained by salting-out and sample genotyping by matrix-assisted laser desorption ionization time-of-flight mass spectrometry based system. LDL-cholesterol, HDL-cholesterol, triglycerides, total cholesterol, glucose and insulin were measured by standard automated methods. Means were compared by t-test or Mann-Whitney test. Univariate and multivariate logistic regression were used to verify association between polymorphisms and lipid and glucose markers. Seven polymorphisms in 5 genes were associated with lipid and glucose parameters. For lipid parameters, the following associations were found: higher LDL-C levels and C allele of rs1554973 (TLR4) and G allele of rs6671879 (NEK7); higher HDL-cholesterol levels and A allele of rs13105517 (TLR2); higher total cholesterol and TT genotype of rs3804099 (TLR2) and G allele of rs6671879 (NEK7); higher triglycerides levels and G allele of rs455060 (NLRC4). For glucose parameters associations were found between C allele of rs7258674 (CARD8) and higher glucose levels, and between C allele of rs212704 (NLRC4) and G allele of rs455060 (NLRC4) and insulin levels. These findings indicate a relationship between polymorphisms of TLRs and NLRs genes and markers of lipid and glucose metabolism.

NLRP3: A promising therapeutic target for autoimmune diseases

NLRP3, a member of nucleotide-binding domain-(NOD) like receptor family, can be found in large varieties of immune and non-immune cells. Upon activation, the NLRP3, apoptosis-associated speck-like protein (ASC) and pro-caspase-1 would assemble into a multimeric protein, called the NLRP3 inflammasome. Then the inflammasome promotes inflammation (through specific cleavage and production of bioactive IL-1β and IL-18) and pyroptotic cell death. Previous studies have indicated the importance of NLRP3 in regulating innate immunity. Recently, numerous studies have revealed their significance in autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc) and inflammatory bowel disease (IBD). In this review, we will briefly discuss the biological features of NLRP3 and summarize the recent progression of the involvement of NLRP3 in the development and pathogenesis of autoimmune diseases, as well as its clinical implications and therapeutic potential.

Association of NLRP1 and NLRP3 Polymorphisms with Psoriasis Vulgaris Risk in the Chinese Han Population

Aim

To clarify the association between the single nucleotide polymorphisms (SNPs) in the NLRP1 and NLRP3 and Psoriasis Vulgaris (PsV) in the Chinese Han population.

Methods

We genotyped eight SNPs, four from NLRP1 (rs8079034, rs11651270, rs11657747, and rs878329) and NLRP3 (rs7512998, rs3806265, rs10754557, and rs10733113) each in 540 patients with PsV and 612 healthy controls in the Chinese Han population using an improved multiplexed ligation detection reaction (iMLDR) method. The genotype and haplotype frequencies were analyzed using a case-control study design.

Results

We identified two SNPs, rs3806265 and rs10754557, in NLRP3 that were significantly associated with PsV. The genotype distribution of the rs3806265 SNP was significantly different between cases and controls (p = 0.0451; OR = 0.791; 95% CI = 0.627–0.998). In the recessive model, the genotype distribution of the rs10754557 SNP was significantly different between cases and controls (p = 0.0344; OR = 1.277; 95% CI = 0.987–1.652). The haplotype analysis of rs3806265 and rs10754557 also presented a significant association of TA haplotype with PsV (χ² = 4.529; p = 0.033).

Conclusion

NLRP3 may play a role in PsV susceptibility in the Chinese Han population.

Nlrp3-dependent IL-1β inhibits CD103+ dendritic cell differentiation in the gut

Inflammatory bowel disease (IBD) is associated with enhanced levels of the IL-1 family cytokines IL-1β and IL-18, which are activated by the Nlrp3 inflammasome. Here, we investigated the role of inflammasome-driven cytokine release on T cell polarization and DC differentiation in steady state and T cell transfer colitis. In vitro and in vivo data showed that IL-1β induces Th17 polarization and increases GM‑CSF production by T cells. Reduced IL-1β levels in Nlrp3-/- mice correlated with enhanced FLT3L levels and increased frequency of tolerogenic CD103+ DC. In the T cell transfer colitis model, Nlrp3 deficiency resulted in lower IL‑1β levels, reduced Th17 immunity, and less severe colitis. Unaltered IL-18 levels in both mouse strains pointed toward Nlrp3-independent processing. Importantly, cohousing revealed that the gut microbiome had no impact on the observed Nlrp3-/- phenotype. This study demonstrates that NLRP3 acts as a molecular switch of intestinal homeostasis by shifting local immune cells toward an inflammatory phenotype via IL-1β.

Orchestration of NLRP3 Inflammasome Activation by Ion Fluxes

The assembly of the NLRP3 inflammasome can promote the release of IL-1β/IL-18 and initiate pyroptosis. Accordingly, the dysregulation of NLRP3 inflammasome activation is involved in a variety of human diseases, including gout, diabetes, and Alzheimer's disease. NLRP3 can sense a variety of structurally unrelated pathogen-associated molecular patterns (PAMPs) or danger-associated molecular patterns (DAMPs) to trigger inflammation, but the unifying mechanism of NLRP3 activation is still poorly understood. Increasing evidence suggests that intracellular ions, such as K⁺, Ca²⁺, and Cl^-, have a significant role in NLRP3 inflammasome activation. Here, we review the current knowledge about the role of ionic fluxes in NLRP3 inflammasome activation and discuss how disturbances in intracellular ionic levels orchestrate different signaling events upstream of NLRP3.

NLRP3 inflammasome driven liver injury and fibrosis: Roles of IL-17 and TNF in mice

The NLRP3 inflammasome, a caspase-1 activation platform, plays a key role in the modulation of liver inflammation and fibrosis. Here, we tested the hypothesis that interleukin 17 (IL-17) and tumor necrosis factor (TNF) are key cytokines involved in amplifying and perpetuating the liver damage and fibrosis resulting from NLRP3 activation. To address this hypothesis, gain-of-function Nlrp3A350V knock-in mice were bred onto il17a and Tnf knockout backgrounds allowing for constitutive Nlrp3 activation in myeloid derived cells in mice deficient in IL-17 or TNF. Livers of Nlrp3A350V knock-in mice exhibited severe liver inflammatory changes characterized by infiltration with neutrophils, increased expression of chemokine (C-X-C motif) ligand (CXCL) 1 and CXCL2 chemokines, activated inflammatory macrophages, and elevated levels of IL-17 and TNF. Mutants with ablation of il17a signal showed fewer neutrophils when compared to intact Nlrp3A350V mutants, but still significant inflammatory changes when compared to the nonmutant il17a knockout littermates. The severe inflammatory changes associated with mutant Nlrp3 were almost completely rescued by Tnf knockout in association with a marked decrease in circulating IL-1β levels. Intact Nlrp3A350V mutants showed changes in liver fibrosis, as evidenced by morphometric quantitation of Sirius Red staining and increased mRNA levels of profibrotic genes, including connective tissue growth factor and tissue inhibitor of matrix metalloproteinase 1. Il17a lacking mutants exhibited amelioration of the aforementioned fibrosis, whereas Tnf-deficient mutants showed no signs of fibrosis when compared to littermate controls. Conclusion: Our study uncovers key roles for TNF and, to a lesser extent, IL-17 as mediators of liver inflammation and fibrosis induced by constitutive NLRP3 inflammasome activation in myeloid-derived cells. These findings may lead to therapeutic strategies aimed at halting the progression of liver injury and fibrogenesis in various liver pathogeneses driven by NLRP3 activation. (Hepatology 2018;67:736-749).

Lower activation of caspase-1 by Staphylococcus epidermidis isolated from prosthetic joint infections compared to commensals

Nosocomial sequence types of Staphylococcus epidermidis dominate in prosthetic joint infections. We examined caspase-1 activation in human neutrophils after incubation with Staphylococcus epidermidis isolated from prosthetic joint infections and normal skin flora. Active caspase-1 was lower after incubation with isolates from prosthetic joint infections than after incubation with commensal isolates. Both host and isolate dependent differences in active caspase-1 were noted. Our results indicate that there might be a host-dependent incapacity to elicit a strong caspase-1 response towards certain strains of S. epidermidis. Further experiments with a larger number of individuals are warranted.

Polymorphisms and expression of inflammasome genes are associated with the development and severity of rheumatoid arthritis in Brazilian patients

OBJECTIVE

In the present study, we analyzed the possible association of inflammasome gene variants and expression to rheumatoid arthritis (RA)'s development and severity in the Brazilian population.

MATERIALS AND METHODS

Thirteen single nucleotide polymorphisms within six inflammasome genes (NLRP1, NLRP3, NLRC4, AIM2, CARD8, CASP1) as well as IL1B and IL18 genes in two different Brazilian populations (from Northeast and Southeast Brazil) were analyzed. We also evaluated inflammasome gene expression profile in resting and LPS + ATP-treated monocytes from RA patients and healthy individuals. For genetic association study, 218 patients and 307 healthy controls were genotyped. For gene expression study, inflammasome genes mRNA levels of 12 patients and ten healthy individuals were assessed by qPCR.

RESULTS

Our results showed that rs10754558 NLRP3 and rs2043211 CARD8 polymorphisms are associated with RA development (p value = 0.044, OR = 1.77, statistical power = 0.999) and severity measured by Health Assessment Questionnaire (HAQ) (p value = 0.03), respectively. Gene expression analyses showed that RA patients display activation of CASP1, IL1B and IL1R genes independently of LPS + ATP activation. In LPS + ATP-treated monocytes, NLRP3 and NLRC4 expressions were also significantly higher in patients compared with controls.

CONCLUSIONS

The first reported results in Brazilian populations support the role of inflammasome in the development of RA.

Association of NLRP3 polymorphisms with susceptibility to primary gouty arthritis in a Chinese Han population

The NLRP3-interleukin1β (IL1β) signaling pathway is involved in monosodium urate (MSU)-mediated inflammation. The aim of this present study was to determine whether single nucleotide polymorphisms (SNPs) in the NLRP3 gene are associated with susceptibility to gouty arthritis (GA) and whether these SNPs alter the expression of components of the NLRP3-IL1β signaling pathway. The rs10754558, rs4612666, and rs1539019 SNPs were detected in 583 patients with GA and 459 healthy subjects. NLRP3 and IL1β mRNA levels in peripheral blood mononuclear cells (PBMCs) and serum IL1β levels were measured in different genotype carriers, and correlations between the NLRP3 SNPs and NLRP3 mRNA, IL1β mRNA, and serum IL1β levels were investigated. The GG genotype of NLRP3 rs10754558 was found to be significantly associated with patients with GA compared to the healthy control subjects via multivariate logistic regression analysis (adjusted OR = 2.68, P = 0.006). The CGA haplotypes were independently associated with patients with GA compared to the healthy control subjects (adjusted OR = 1.968, P = 0.02). The levels of NLRP3 mRNA, IL1β mRNA, and serum IL1β in the patients with GA were significantly different among the three genotypes of rs10754558 (all P < 0.01). The GG genotype of rs10754558 and the CGA haplotype of rs4612666-C, rs10754558-G, and rs1539019-A are both independent risk factors for primary GA development. The rs10754558 polymorphism might participate in regulating immune and inflammation responses in patients with GA by influencing the expression of components of the NLRP3 inflammasome. Future multicenter studies aimed at replicating these findings in an independent population as well as functional tests will aid in further defining the role of these SNPs in the development of GA.

COPs and POPs Patrol Inflammasome Activation

Sensing and responding to pathogens and tissue damage is a core mechanism of innate immune host defense, and inflammasomes represent a central cytosolic pattern recognition receptor pathway leading to the generation of the pro-inflammatory cytokines interleukin-1β and interleukin-18 and pyroptotic cell death that causes the subsequent release of danger signals to propagate and perpetuate inflammatory responses. While inflammasome activation is essential for host defense, deregulated inflammasome responses and excessive release of inflammatory cytokines and danger signals are linked to an increasing spectrum of inflammatory diseases. In this review, we will discuss recent developments in elucidating the role of PYRIN domain-only proteins (POPs) and the related CARD-only proteins (COPs) in regulating inflammasome responses and their impact on inflammatory disease.

NLRP3 Inflammasome Activation-Mediated Pyroptosis Aggravates Myocardial Ischemia/Reperfusion Injury in Diabetic Rats

The reactive oxygen species- (ROS-) induced nod-like receptor protein-3 (NLRP3) inflammasome triggers sterile inflammatory responses and pyroptosis, which is a proinflammatory form of programmed cell death initiated by the activation of inflammatory caspases. NLRP3 inflammasome activation plays an important role in myocardial ischemia/reperfusion (MI/R) injury. Our present study investigated whether diabetes aggravated MI/R injury through NLRP3 inflammasome-mediated pyroptosis. Type 1 diabetic rat model was established by intraperitoneal injection of streptozotocin (60 mg/kg). MI/R was induced by ligating the left anterior descending artery (LAD) for 30 minutes followed by 2 h reperfusion. H9C2 cardiomyocytes were exposed to high glucose (HG, 30 mM) conditions and hypoxia/reoxygenation (H/R) stimulation. The myocardial infarct size, CK-MB, and LDH release in the diabetic rats subjected to MI/R were significantly higher than those in the nondiabetic rats, accompanied with increased NLRP3 inflammasome activation and increased pyroptosis. Inhibition of inflammasome activation with BAY11-7082 significantly decreased the MI/R injury. In vitro studies showed similar effects, as BAY11-7082 or the ROS scavenger N-acetylcysteine, attenuated HG and H/R-induced H9C2 cell injury. In conclusion, hyperglycaemia-induced NLRP3 inflammasome activation may be a ROS-dependent process in pyroptotic cell death, and NLRP3 inflammasome-induced pyroptosis aggravates MI/R injury in diabetic rats.

Inhibition of NLRP3 Inflammasome Prevents LPS-Induced Inflammatory Hyperalgesia in Mice: Contribution of NF-κB, Caspase-1/11, ASC, NOX, and NOS Isoforms

The nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3), an intracellular signaling molecule that senses many environmental- and pathogen/host-derived factors, has been implicated in the pathogenesis of several diseases associated with inflammation. It has been suggested that NLRP3 inflammasome inhibitors may have a therapeutic potential in the treatment of NLRP3-related inflammatory diseases. The aim of this study was to determine whether inhibition of NLRP3 inflammasome prevents inflammatory hyperalgesia induced by lipopolysaccharide (LPS) in mice as well as changes in expression/activity of nuclear factor κB (NF-κB), caspase-1/11, nicotinamide adenine dinucleotide phosphate oxidase (NOX), and endothelial/neuronal/inducible nitric oxide synthase (eNOS/nNOS/iNOS) that may regulate NLRP3/apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC)/pro-caspase-1 inflammasome formation and activity by using a selective NLRP3 inflammasome inhibitor, MCC950. Male mice received saline (10 ml/kg; i.p.), LPS (10 mg/kg; i.p.), and/or MCC950 (3 mg/kg; i.p.). Reaction time to thermal stimuli within 1 min was evaluated after 6 h. The mice were killed and the brains, hearts, and lungs were collected for measurement of NF-κB, caspase-1, caspase-11, NLRP3, ASC, NOX subunits (gp91^phox; NOX2), and p47^phox; NOXO2), nitrotyrosine, eNOS, nNOS, iNOS, and β-actin protein expression, NOS activity, and interleukin (IL)-1β levels. LPS-induced hyperalgesia was associated with a decrease in eNOS, nNOS, and iNOS protein expression and activity as well as an increase in expression of NF-κB p65, caspase-1 p20, caspase-11 p20, NLRP3, ASC, gp91^phox, p47^phox, and nitrotyrosine proteins in addition to elevated IL-1β levels. The LPS-induced changes were prevented by MCC950. The results suggest that inhibition of NLRP3/ASC/pro-caspase-1 inflammasome formation and activity prevents inflammatory hyperalgesia induced by LPS in mice as well as changes in NF-κB, caspase-11, NOX2, NOXO2, and eNOS/nNOS/iNOS expression/activity.

Periodic Fever with Aphthous Stomatitis, Pharyngitis, and Cervical Adenitis Syndrome Is Associated with a CARD8 Variant Unable To Bind the NLRP3 Inflammasome

Periodic fever with aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) is a relatively common autoinflammatory condition that primarily affects children. Although tendencies were reported for this syndrome, genetic variations influencing risk and disease progression are poorly understood. In this study, we performed next-generation sequencing for 82 unrelated PFAPA patients and identified a frameshift variant in the CARD8 gene (CARD8-FS). Subsequently, we compared the frequency of CARD8-FS carriers in our PFAPA cohort (13.9%) with a healthy local population group (3.2%) and found a significant association between the CARD8-FS polymorphism and risk for PFAPA syndrome (p = 0.012; odds ratio: 4.96 [95% confidence interval, 1.33-18.47]). Moreover, CARD8-FS carriers display a distinct PFAPA phenotype that is characterized by a higher prevalence of symptoms out of flares and oral aphthosis (both p = 0.02 compared with PFAPA patients without the frameshift variant). CARD8 encodes a protein component of the NLRP3 inflammasome, which plays an important role in inflammation and contributes to the pathology of various autoinflammatory diseases. We found that the CARD8-FS variant led to a truncated CARD8 protein lacking the FIIND and CARD domains. As a result, the mutant CARD8 protein lost the ability to interact with the NOD domain of NLRP3. In summary, these results identify a new CARD8 variant associated with PFAPA and further suggest that disruption of the interaction between CARD8 and NLRP3 can regulate autoinflammation in patients.