Molecular Characterization of the NLRC4 Expression in Relation to Interleukin-18 Levels

Genetically predicted circulating interleukin-18 levels are associated with risk of systemic lupus erythematosus and type 1 diabetes

OBJECTIVE

Interleukin-18 (IL-18) is a proinflammatory cytokine. This study aims to determine whether there is a causal relationship between circulating IL-18 concentrations and the risk of inflammatory and autoimmune diseases.

METHODS

We collected significant single nucleotide polymorphisms (SNPs) associated with circulating IL-18 levels (p < 5 × 10-8) as instrumental variables (IVs) from a genome-wide association study (GWAS) involving 21,758 individuals of European descent. We mainly employed the inverse-variance weighed (IVW) method of two-sample Mendelian randomization (TSMR) analysis to estimate the causality of circulating IL-18 levels on inflammatory and autoimmune diseases.

RESULTS

The IVW method results showed evidence of a causal relationship between IL-18 and the risk of systemic lupus erythematosus (SLE) (OR = 1.32; 95% CI 1.15, 1.50; p < .001) and type 1 diabetes (T1D) (OR = 1.22; 95% CI 1.06, 1.42; p = .007) in individuals of European ancestry. No significant heterogeneity or horizontal pleiotropy for SLE and T1D was detected. The sensitivity analysis, which involved removing confounding SNP, produced similar results for SLE and T1D. The results of sensitivity analysis using leave-one-out method indicated no single SNP significantly influenced the analysis results. However, we did not find any significant findings for multiple sclerosis, psoriasis, asthma, and osteoarthritis.

CONCLUSIONS

Our analyses suggest that circulating IL-18 is significantly related to SLE and T1D and may serve as a potential target for the treatment of these diseases.

Biological and clinical roles of IL-18 in inflammatory diseases

Several new discoveries have revived interest in the pathogenic potential and possible clinical roles of IL-18. IL-18 is an IL-1 family cytokine with potent ability to induce IFNγ production. However, basic investigations and now clinical observations suggest a more complex picture. Unique aspects of IL-18 biology at the levels of transcription, activation, secretion, neutralization, receptor distribution and signalling help to explain its pleiotropic roles in mucosal and systemic inflammation. Blood biomarker studies reveal a cytokine for which profound elevation, associated with detectable 'free IL-18', defines a group of autoinflammatory diseases in which IL-18 dysregulation can be a primary driving feature, the so-called 'IL-18opathies'. This impressive specificity might accelerate diagnoses and identify patients amenable to therapeutic IL-18 blockade. Pathogenically, human and animal studies identify a preferential activation of CD8+ T cells over other IL-18-responsive lymphocytes. IL-18 agonist treatments that leverage the site of production or subversion of endogenous IL-18 inhibition show promise in augmenting immune responses to cancer. Thus, the unique aspects of IL-18 biology are finally beginning to have clinical impact in precision diagnostics, disease monitoring and targeted treatment of inflammatory and malignant diseases.

Rapid Inflammasome Activation Is Attenuated in Post-Myocardial Infarction Monocytes

Inflammasomes are crucial gatekeepers of the immune response, but their maladaptive activation associates with inflammatory pathologies. Besides canonical activation, monocytes can trigger non-transcriptional or rapid inflammasome activation that has not been well defined in the context of acute myocardial infarction (AMI). Rapid transcription-independent inflammasome activation induced by simultaneous TLR priming and triggering stimulus was measured by caspase-1 (CASP1) activity and interleukin release. Both classical and intermediate monocytes from healthy donors exhibited robust CASP1 activation, but only classical monocytes produced high mature interleukin-18 (IL18) release. We also recruited a limited number of coronary artery disease (CAD, n=31) and AMI (n=29) patients to evaluate their inflammasome function and expression profiles. Surprisingly, monocyte subpopulations isolated from blood collected during percutaneous coronary intervention (PCI) from AMI patients presented diminished CASP1 activity and abrogated IL18 release despite increased NLRP3 gene expression. This unexpected attenuated rapid inflammasome activation was accompanied by a significant increase of TNFAIP3 and IRAKM expression. Moreover, TNFAIP3 protein levels of circulating monocytes showed positive correlation with high sensitive troponin T (hsTnT), implying an association between TNFAIP3 upregulation and the severity of tissue injury. We suggest this monocyte attenuation to be a protective phenotype aftermath following a very early inflammatory wave in the ischemic area. Damage-associated molecular patterns (DAMPs) or other signals trigger a transitory negative feedback loop within newly recruited circulating monocytes as a mechanism to reduce post-injury tissue damage.

NLRC4 Gene Single Nucleotide Polymorphisms Are Associated with the Prognosis of Hemophagocytic Lymphohistiocytosis

OBJECTIVE

To analyze and study the correlation between NLR family CARD domain-containing 4 (NLRC4) gene single nucleotide polymorphisms and the prognosis of patients with hemophagocytic lymphohistiocytosis (HLH).

METHODS

In this study, we retrospectively studied the clinical data of 62 HLH patients, including 40 males and 22 females. The genomic DNA was extracted, and the genotypes at rs385076 locus and rs479333 locus of the NLRC4 gene were analyzed. The level of blood interleukin-18 (IL-18) was analyzed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared with the TT genotype at the NLRC4 gene rs385076 locus, the mortality of HLH patients with TC genotype and CC genotype was higher (RR = 3.205, 95% CI: 1.277-4.788, p = 0.012; RR = 3.052, 95% CI: 1.098-4.753, p = 0.031). Taking the CC genotype at rs479333 of the NLRC4 gene as a reference, HLH patients with CG genotype and GG genotype had a higher risk of death (RR = 3.475, 95% CI: 1.488-5.775, p = 0.003; RR = 2.986, 95% CI: 1.014-5.570, p = 0.047). NLRC4 gene rs385076 T>C and rs479333 C>G were significantly related to the poor prognosis of HLH patients. The area under the curve (AUC) of the receiver operating curve (ROC) for the prognostic outcome of HLH with serum IL-18 level was 0.6813 (95% CI: 0.5365-0.8260, p = 0.0189). NLRC4 gene rs385076 T>C and rs479333 C>G were related to higher serum IL-18 levels.

CONCLUSION

NLRC4 gene rs385076 T>C and rs479333 C>G are related to the poor prognosis of HLH patients.

Genetic contribution and functional impairment of inflammasome in sickle cell disease

BACKGROUND

Sickle cell disease (SCD), one of the most common single-gene disorders, is caused by mutations in the hemoglobin ß-chain gene. Clinical presentation is heterogeneous, and inflammation is a common condition. Thereby, we hypothesized that inflammasome and related cytokine IL-1ß could represent significant SCD pathogenesis contributors.

MATERIAL AND METHODS

161 SCD (SS/Sβ) patients were enrolled for the study. Seven single nucleotide polymorphisms (SNPs) in 5 inflammasome genes (NLRP1, NLRP3, NLRC4, CARD8, IL1B) were selected based on minor allele frequency. Total peripheral blood mononuclear cells (PBMC) and monocytes were isolated from 10 out of 161 SCD patients (HbSS) and 10 healthy donors (control group, Ctrl) for inflammasome analysis.

RESULTS

SCD patients presented a functional impairment of inflammasome, with monocytes and peripheral blood mononuclear cells (PBMC) exhibiting a different NLRP3 inflammasome activation rate. Gain-of-function variants in NLRP1 and IL1B genes resulted associated with a mild SCD clinical presentation.

DISCUSSION

Our results can contribute to the understanding of SCD inflammation. SCD patients showed possible exhaustion of monocytes due to chronic inflammation, moreover others cells in PBMC can contribute to the NLRP3 inflammasome activation. NLRP1 gain-of-function was associated with mild clinical presentation, suggesting that other inflammasome receptors can be involved in SCD. This is the first study reporting a significant contribution of inflammasome SNPs in SCD.

Cannabinoids as Key Regulators of Inflammasome Signaling: A Current Perspective

Inflammasomes are cytoplasmic inflammatory signaling protein complexes that detect microbial materials, sterile inflammatory insults, and certain host-derived elements. Inflammasomes, once activated, promote caspase-1–mediated maturation and secretion of pro-inflammatory cytokines, interleukin (IL)-1β and IL-18, leading to pyroptosis. Current advances in inflammasome research support their involvement in the development of chronic inflammatory disorders in contrast to their role in regulating innate immunity. Cannabis (marijuana) is a natural product obtained from the Cannabis sativa plant, and pharmacologically active ingredients of the plant are referred to as cannabinoids. Cannabinoids and cannabis extracts have recently emerged as promising novel drugs for chronic medical conditions. Growing evidence indicates the potent anti-inflammatory potential of cannabinoids, especially Δ⁹-tetrahydrocannabinol (Δ⁹-THC), cannabidiol (CBD), and synthetic cannabinoids; however, the mechanisms remain unclear. Several attempts have been made to decipher the role of cannabinoids in modulating inflammasome signaling in the etiology of chronic inflammatory diseases. In this review, we discuss recently published evidence on the effect of cannabinoids on inflammasome signaling. We also discuss the contribution of various cannabinoids in human diseases concerning inflammasome regulation. Lastly, in the milieu of coronavirus disease-2019 (COVID-19) pandemic, we confer available evidence linking inflammasome activation to the pathophysiology of COVID-19 suggesting overall, the importance of cannabinoids as possible drugs to target inflammasome activation in or to support the treatment of a variety of human disorders including COVID-19.

Combining Host Genetics and Functional Analysis to Depict Inflammasome Contribution in Tuberculosis Susceptibility and Outcome in Endemic Areas

The interplay between M. tuberculosis (Mtb) and humans is multifactorial. The susceptibility/resistance profile and the establishment of clinical tuberculosis (TB) still remains elusive. The gain-of-function variant rs10754558 in the NLRP3 gene (found in 30% of the world population) confers protection against the development of TB, indicating a prominent role played by NLRP3 inflammasome against Mtb. Through genotype-guided assays and various Mtb strains (BCG, H37Rv, Beijing-1471, MP287/03), we demonstrate that Mtb strains activate inflammasome according to the NLRP3/IL-1ß or NLRC4/IL18 preferential axis. NLRP3 and NLRC4 genetic variants contribute to the presentation of TB. For the first time, we have shown that loss-of-function variants in NLRC4 significantly contribute to the development of extra-pulmonary TB. The analysis of inflammasome activation in a cohort of TB patients and their “household contacts” (CNT) revealed that plasma IL-1ß/IFN-α ratio lets us distinguish patients from Mtb-exposed-but-healthy individuals from an endemic region. Moreover, NLRP3 inflammasome seemed “exhausted” in TB patients compared to CNT, indicating a more efficient activation of inflammasome in resistant individuals. These findings suggest that inflammasome genetics as well as virulence-dependent level of inflammasome activation contribute to the onset of a susceptible/resistant profile among Mtb-exposed individuals.

A Common NLRC4 Gene Variant Associates With Inflammation and Pulmonary Function in Human Immunodeficiency Virus and Tuberculosis

BACKGROUND

Inflammasomes mediate inflammation in adults living with both human immunodeficiency virus (HIV) and tuberculosis (TB), but the relevance of inflammasome gene polymorphisms in TB-associated pulmonary damage is unknown. We hypothesized that functional single-nucleotide polymorphisms (SNPs) in inflammasome pathway genes modify systemic and pulmonary inflammation, contributing to respiratory impairment in adults living with HIV/pulmonary TB.

METHODS

This was a prospective cohort study set in South Africa following individuals living with HIV/TB up to 48 weeks post-antiretroviral therapy (ART) initiation. Ten functional SNPs in 5 inflammasome pathway genes were related to circulating inflammatory biomarkers and lung function assessed by spirometry pre- and post-ART initiation. Analyses used 2-sided t tests, Wilcoxon rank sum tests, Spearman correlation coefficients, linear regression, and generalized estimating equation models.

RESULTS

Among 102 patients with baseline samples, the minor allele (T) in NLRC4 rs385076 was independently associated with lower levels of interleukin (IL)-18 and IL-6 before and up to 12 weeks post-ART initiation (Benjamini-Hochberg corrected P values < .02). Patients with the CT/TT genotypes also had improved lung function vs CC patients up to 48 weeks post-ART initiation (forced vital capacity, 206 mL higher; 95% confidence interval [CI], 67-345 mL; P = .004 and forced expiratory volume in 1 second, 143 mL higher; 95% CI, 11-274 mL; P = .034).

CONCLUSIONS

A common SNP in the NLRC4 inflammasome may modify TB-associated inflammation in clinically relevant ways. This SNP may identify high-risk groups for lung damage in TB. Inhibition of NLRC4 activity may be an important approach for TB host-directed therapy.

Associations between NLRC4 Gene Polymorphisms and Autoimmune Thyroid Disease

Background

Many studies have shown that NLRC4 inflammasome polymorphisms are associated with a variety of autoimmune diseases, but the associations between NLRC4 polymorphisms and autoimmune thyroid diseases (AITDs) are unclear. Our research was aimed at identifying the correlations between NLRC4 polymorphisms and AITDs.

Methods

Hi-SNP high-throughput genotyping technology was used for detecting four single-nucleotide polymorphisms (SNPs) of NLRC4 in 1005 AITDs patients (including 629 Graves' disease and 376 Hashimoto's thyroiditis) and 781 healthy controls.

Results

Compared with healthy controls, the allele frequencies and genotype distribution of rs385076 were statistically related to AITDs (P = 0.016 and P = 0.048, respectively) and Hashimoto's thyroiditis (P = 0.022 and P = 0.046, respectively). Before adjusting for age and gender, rs385076 and AITDs had a significant association in three models of allele model, dominant model, and homozygous model. After adjusting for age and gender, in the above three models, there is still a clear relationship between them. Before adjusting for age and gender, there were prominent discrepancy between rs385076 and Hashimoto's thyroiditis in the allele model (OR = 0.81, 95% CI 0.67-0.97; P = 0.021) and the dominant model (OR = 0.73, 95% CI 0.57-0.94; P = 0.014), after adjusting for age and gender, rs385076 and Hashimoto's thyroiditis were significantly related to allele model, dominant model, and homozygous model. However, rs455060, rs212704, and rs675712 were not related to AITDs in our study.

Conclusion

NLRC4 rs385076 was found to have a significant association with Hashimoto's thyroiditis for the first time. It laid a foundation for the disclosure of the pathogenesis of AITDs, and provided a possible treatment prospect for HT.

Inflammasome genetics and complex diseases: a comprehensive review

The inflammasome is a cytoplasmic multiprotein complex responsible for the activation of inflammatory caspases (caspase-1, -4, and -5) in response to pathogen- and/or damage-associated molecular patterns or to homeostasis-altering molecular pathways, and for the consequent release of the pro-inflammatory cytokines interleukin (IL)-1ß and IL-18. Taking in account the complexity of inflammasome activation and that several regulatory steps are involved in maintaining its physiologic role in homeostasis and innate immune response, it does not surprise that several genetic variants in inflammasome components have been associated with common pathologies in the general population, such as autoimmune disorders, cardiovascular diseases, obesity and associated metabolic syndrome, neurodegenerative diseases, and cancer. Moreover, the susceptibility to infectious agents and/or to develop severe complications during infections also has been related to inflammasome genetics. In this work, we revised genetic association studies about polymorphisms of main inflammasome genes in sterile as well as infectious diseases, trying to depict the genetic contribution of inflammasome in disease pathogenesis.

Epigenetics meets proteomics in an epigenome-wide association study with circulating blood plasma protein traits

DNA methylation and blood circulating proteins have been associated with many complex disorders, but the underlying disease-causing mechanisms often remain unclear. Here, we report an epigenome-wide association study of 1123 proteins from 944 participants of the KORA population study and replication in a multi-ethnic cohort of 344 individuals. We identify 98 CpG-protein associations (pQTMs) at a stringent Bonferroni level of significance. Overlapping associations with transcriptomics, metabolomics, and clinical endpoints suggest implication of processes related to chronic low-grade inflammation, including a network involving methylation of NLRC5, a regulator of the inflammasome, and associated pQTMs implicating key proteins of the immune system, such as CD48, CD163, CXCL10, CXCL11, LAG3, FCGR3B, and B2M. Our study links DNA methylation to disease endpoints via intermediate proteomics phenotypes and identifies correlative networks that may eventually be targeted in a personalized approach of chronic low-grade inflammation.

Polymorphisms of the NLRC4 Gene are Associated with the Onset Age, Positive Rate of GADA and 2-h Postprandial C-Peptide in Patients with Type 1 Diabetes

PURPOSE

The purpose of this study was to clarify the association between the NLRC4 gene and the susceptibility and clinical characteristics of type 1 diabetes (T1D) in a Chinese Han population.

PATIENTS AND METHODS

A case-control study was performed in a Chinese Han population including 510 classical T1D patients and 531 healthy controls. rs212704 and rs385076 of the NLRC4 gene were genotyped by MassARRAY. The frequency distributions of alleles and genotypes of polymorphisms in the NLRC4 gene were compared by logistic regression and the chi-square test. The relationships between the polymorphisms of the NLRC4 gene and various clinical characteristics were analyzed by Kruskal-Wallis one-way ANOVA. The statistical power was calculated by Quanto software.

RESULTS

1) rs385076 of the NLRC4 gene was significantly correlated with the onset age of T1D patients and the positive rate of GADA. The relationship between rs212704 and 2-h postprandial C-peptide was statistically significant. 2) There was no significant difference in the frequency distributions of the genotypes and alleles of rs212704 and rs385076 between T1D patients and controls. 3) rs212704 and rs385076 were not correlated with T1D susceptibility under different genetic models.

CONCLUSION

rs212704 was associated with 2-h postprandial C-peptide, while rs385076 of the NLRC4 gene was associated with the onset age and positive rate of GADA in patients with T1D.

Variants in NLRP3 and NLRC4 inflammasome associate with susceptibility and severity of multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a neurodegenerative disease of central nervous system (CNS) with autoimmune and inflammatory characteristics, and a still uncertain pathogenesis. Early events as well as evolution of MS are heterogeneous (three main clinical forms) and multifactorial. Genome-wide association studies indicate that MS pathogenesis shares features with both autoimmune and inflammatory diseases. Innate immunity has been recently proved to be an important factor in MS. Genetic variants in inflammasome components have been associated with both autoimmune and neurodegenerative diseases, letting us hypothesize that inflammasome, and related cytokines IL-1ß and IL-18, could represent important contributors in MS pathogenesis, and eventually explain, at least in part, the heterogeneity observed in MS patients.

AIM

To evaluate the contribution of inflammasome in MS, in term of (a) genetic effect on development, severity and/or prognosis, and (b) complex activation in peripheral blood as a measure of systemic inflammation.

METHODS

Functional genetic variants in inflammasome components were analyzed in a cohort of MS patients, by the use of allele-specific assays and qPCR. Multivariate analysis was performed based on clinical form (recurrent remittent/RR, primary progressive/PP or secondary progressive/SP), severity index (EDSS) and progression index (PI), response to IFN-ß treatment. Peripheral blood monocytes (PBM) of patients were examined for inflammasome activation and expression profile.

RESULTS AND DISCUSSION

Variants associated with low serum levels of IL-18 were significantly less frequent in MS patients than in controls, suggesting a protective role of diminished IL-18-mediate inflammation in MS development. On the other hands, gain-of-function variants in NLRP3 (Q705K) and IL1B (-511 C >T) associated with severity and progression of MS, suggesting that a constitutive activation of NLRP3 inflammasome could represent a risk factor for MS clinical presentation. Accordingly, -511C >T SNP resulted more frequent in progressive forms than in RR MS, reinforcing the idea that increased inflammasome activation characterized bad prognosis of MS. Altogether these findings corroborate previous data about the harmful role of NLRP3 inflammasome in experimental autoimmune encephalitis (EAE). Moreover, we reported for the first time the beneficial effect of NLRC4 rs479333 G >C variant in MS progression and in the response to IFN-ß treatment. This intronic polymorphism have been previously associated to decreased NLRC4 transcription and low IL-18 serum level, indicated once more that less activation of inflammasome and IL-18 production are beneficial for MS patients. PBM analysis showed that MS cells express higher level of inflammasome genes than HD ones, and are more prone to respond to a classical NLRP3 stimulus than HD.

Systemic inflammation and causal risk for Alzheimer's dementia: Possibilities and limitations of a Mendelian randomization approach

Epidemiological studies have implicated systemic inflammation in the development of Alzheimer's disease (AD). However, these observations have been subject to residual confounding and reverse causation. We applied Mendelian randomization approaches to address this. We did not identify any causal associations between serum interleukin (IL)-18, IL-1ra, IL-6, or erythrocyte sedimentation rate (ESR) concentrations and AD. Our findings are limited by the low number of available instruments, though some of those identified (e.g., IL-6) were of sufficient power to indicate true negative results. Taken together, it appears there is no evidence for a causal association between these serum inflammatory cytokines and AD.

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.

Common Variation in NLRP3 Is Associated With Early Death and Elevated Inflammasome Biomarkers Among Advanced HIV/TB Co-infected Patients in Botswana

Background

Elevated inflammation is associated with early mortality among HIV/tuberculosis (TB) patients starting antiretroviral therapy (ART); however, the sources of immune activation are unclear. We hypothesized that common variation in innate immune genes contributes to excessive inflammation linked to death. As single nucleotide polymorphisms (SNPs) in inflammasome pathway genes can increase risk for inflammatory diseases, we investigated their association with early mortality among a previously described cohort of HIV/TB patients initiating ART in Botswana.

Methods

We genotyped 8 SNPs within 5 inflammasome pathway genes and determined their association with death. For adjusted analyses, we used a logistic regression model. For SNPs associated with mortality, we explored their relationship with levels of systemic inflammatory markers using a linear regression model.

Results

Ninety-four patients in the parent study had samples for genetic analysis. Of these, 82 (87%) were survivors and 12 (13%) died within 6 months of starting ART. In a logistic regression model, NLRP3 rs10754558 was independently associated with a 4.1-fold increased odds of death (95% confidence interval, 1.04–16.5). In adjusted linear regression models, the NLRP3 rs10754558-G allele was linked to elevated IL-18 at baseline (Beta, 0.23; SE, 0.10; P = .033) and week 4 post-ART (Beta, 0.24; SE, 0.11; P = .026). This allele was associated with increased MCP-1 at baseline (Beta, 0.24; SE, 0.10; P = .02) and IL-10 (Beta, 0.27; SE, 0.11; P = .013) at week 4 post-ART.

Conclusion

The NLRP3 rs10754558-G SNP is associated with an increased risk for early mortality in HIV/TB patients initiating ART. These patients may benefit from therapies that decrease inflammasome-mediated inflammation.

Genetics of Inflammasomes

Mutations in inflammasome genes are responsible for rare monogenic and polygenic autoinflammatory diseases. On the other side, genetic polymorphisms in the same molecules contribute to the development of common multifactorial diseases (i.e., autoimmune diseases, cardiovascular pathologies, cancer). In this chapter we depicted the current knowledge about inflammasome genetics.

Expression of specific inflammasome gene modules stratifies older individuals into two extreme clinical and immunological states

Low-grade, chronic inflammation has been associated with many diseases of aging, but the mechanisms responsible for producing this inflammation remain unclear. Inflammasomes can drive chronic inflammation in the context of an infectious disease or cellular stress, and they trigger the maturation of interleukin-1β (IL-1β). Here we find that the expression of specific inflammasome gene modules stratifies older individuals into two extremes: those with constitutive expression of IL-1β, nucleotide metabolism dysfunction, elevated oxidative stress, high rates of hypertension and arterial stiffness; and those without constitutive expression of IL-1β, who lack these characteristics. Adenine and N⁴-acetylcytidine, nucleotide-derived metabolites that are detectable in the blood of the former group, prime and activate the NLRC4 inflammasome, induce the production of IL-1β, activate platelets and neutrophils and elevate blood pressure in mice. In individuals over 85 years of age, the elevated expression of inflammasome gene modules was associated with all-cause mortality. Thus, targeting inflammasome components may ameliorate chronic inflammation and various other age-associated conditions.