Common genetic variations in the NALP3 inflammasome are associated with delayed apoptosis of human neutrophils

House ammonia exposure causes alterations in microbiota, transcriptome, and metabolome of rabbits

Introduction

Pollutant gas emissions in the current production system of the livestock industry have negative influences on environment as well as the health of farm staffs and animals. Although ammonia (NH3) is considered as the primary and harmful gas pollutant in the rabbit farm, less investigation has performed to determine the toxic effects of house ammonia exposure on rabbit in the commercial confined barn.

Methods

In this study, we performed multi-omics analysis on rabbits exposed to high and low concentration of house ammonia under similar environmental conditions to unravel the alterations in nasal and colonic microbiota, pulmonary and colonic gene expression, and muscular metabolic profile.

Results and discussion

The results showed that house ammonia exposure notably affected microbial structure, composition, and functional capacity in both nasal and colon, which may impact on local immune responses and inflammatory processes. Transcriptome analysis indicated that genes related to cell death (MCL1, TMBIM6, HSPB1, and CD74) and immune response (CDC42, LAMTOR5, VAMP8, and CTSB) were differentially expressed in the lung, and colonic genes associated with redox state (CAT, SELENBP1, GLUD1, and ALDH1A1) were significantly up-regulated. Several key differentially abundant metabolites such as L-glutamic acid, L-glutamine, L-ornithine, oxoglutaric acid, and isocitric acid were identified in muscle metabolome, which could denote house ammonia exposure perturbed amino acids, nucleotides, and energy metabolism. In addition, the widespread and strong inter-system interplay were uncovered in the integrative correlation network, and central features were confirmed by in vitro experiments. Our findings disclose the comprehensive evidence for the deleterious effects of house ammonia exposure on rabbit and provide valuable information for understanding the underlying impairment mechanisms.

RAGE contributes to allergen driven severe neutrophilic airway inflammation via NLRP3 inflammasome activation in mice

Background

Asthma is a major public healthcare burden, affecting over 300 million people worldwide. While there has been great progress in the treatment of asthma, subsets of patients who present with airway neutrophilia, often have more severe disease, and tend to be resistant to conventional corticosteroid treatments. The receptor for advanced glycation endproducts (RAGE) plays a central role in the pathogenesis of eosinophilic asthma, however, it's role in neutrophilic asthma remains largely uninvestigated.

Methods

A mouse model of severe steroid resistant neutrophilic airway disease (SSRNAD) using the common fungal allergen Alternaria alternata (AA) was employed to evaluate the effects of genetic ablation of RAGE and pharmacological inhibition of the NLRP3 inflammasome on neutrophilic airway inflammation.

Results

AA exposure induced robust neutrophil-dominant airway inflammation and increased BALF levels of Th1/Th17 cytokines in wild-type mice, which was significantly reduced in RAGE^-/- mice. Serum levels of IgE and IgG1 were increased similarly in both wild-type and RAGE^-/- mice. Pharmacological inhibition of NLRP3 blocked the effects of AA exposure and NLRP3 inflammasome activation was RAGE-dependent. Neutrophil extracellular traps were elevated in the BALF of wild-type but not RAGE^-/- mice and an atypical population of SiglecF+ neutrophils were identified in the BALF. Lastly, time-course studies found that RAGE expression promoted sustained neutrophil accumulation in the BALF of mice in response to AA.

Staphylococcus aureus adaptive evolution: Recent insights on how immune evasion, immunometabolic subversion and host genetics impact vaccine development

Despite meritorious attempts, a S. aureus vaccine that prevents infection or mitigates severity has not yet achieved efficacy endpoints in prospective, randomized clinical trials. This experience underscores the complexity of host-S. aureus interactions, which appear to be greater than many other bacterial pathogens against which successful vaccines have been developed. It is increasingly evident that S. aureus employs strategic countermeasures to evade or exploit human immune responses. From entering host cells to persist in stealthy intracellular reservoirs, to sensing the environmental milieu and leveraging bacterial or host metabolic products to reprogram host immune responses, S. aureus poses considerable challenges for the development of effective vaccines. The fact that this pathogen causes distinct types of infections and can undergo transient genetic, transcriptional or metabolic adaptations in vivo that do not occur in vitro compounds challenges in vaccine development. Notably, the metabolic versatility of both bacterial and host immune cells as they compete for available substrates within specific tissues inevitably impacts the variable repertoire of gene products that may or may not be vaccine antigens. In this respect, S. aureus has chameleon phenotypes that have alluded vaccine strategies thus far. Nonetheless, a number of recent studies have also revealed important new insights into pathogenesis vulnerabilities of S. aureus. A more detailed understanding of host protective immune defenses versus S. aureus adaptive immune evasion mechanisms may offer breakthroughs in the development of effective vaccines, but at present this goal remains a very high bar. Coupled with the recent advances in human genetics and epigenetics, newer vaccine technologies may enable such a goal. If so, future vaccines that protect against or mitigate the severity of S. aureus infections are likely to emerge at the intersection of precision and personalized medicine. For now, the development of S. aureus vaccines or alternative therapies that reduce mortality and morbidity must continue to be pursued.

Dermal exposure to cobalt studied in vitro in keratinocytes - effects of cobalt exposure on inflammasome activated cytokines, and mRNA response

BACKGROUND

Cobalt is a dermal sensitizer, and keratinocytes respond to cobalt exposure by releasing proinflammatory mediators, regulating the immune response.

OBJECTIVE

To determine the effect of cobalt on the inflammasome associated cytokine- and gene expression in cultured human keratinocytes (HaCaT). Cultivation in low- or high calcium conditions model separate differentiation states of keratinocytes in the skin.

METHOD

HaCaT cells in two different states of differentiation were exposed to cobalt chloride and caspase-1 activity as well as the production of IL-1β, IL-18 and gene expression of IL1B, IL18, NLRP3, CASP1, and PYCARD was quantified.

RESULTS

High cobalt chloride exposure mediated significant increase in caspase-1 activity, cytokine levels, and IL1B and NLRP3 expression with a corresponding regulatory decrease for CASP1 and PYCARD expression. No difference between high- and low calcium culturing conditions modelling differentiation states was detected.

CONCLUSIONS

Our data suggest that HaCaT cells respond with inflammmasome associated activity upon cobalt exposure in a concentration-dependent manner. These mechanisms could be of importance for the understanding of the pathophysiology behind allergic sensitization to dermal cobalt exposure.

Galectin-3: a new biomarker for differentiating periodic fever, adenitis, pharyngitis, aphthous stomatitis (PFAPA) syndrome from familial Mediterranean fever?

Differentiating PFAPA (periodic fever, aphthosis, pharyngitis, and adenitis) syndrome from familial Mediterranean fever (FMF) could be challenging in some cases. Galectin-3 is a lectin with regulatory functions in apoptosis and inflammation. We aimed to test whether galectin-3 could be a biomarker for differentiating PFAPA syndrome from FMF. Patients with PFAPA syndrome, FMF, cryopyrin-associated periodic syndrome (CAPS), and streptococcal pharyngitis, and healthy controls were included in this study. Serum galectin-3 levels were measured using enzyme-linked immunosorbent assay. Eighty-seven patients (36 with PFAPA, 39 with FMF, 8 with CAPS, 4 with streptococcal pharyngitis), and 17 healthy controls were included. Blood samples were drawn during attacks from 20 PFAPA and 7 FMF patients and attack-free periods from 22 PFAPA, 35 FMF, and 8 CAPS patients. The median serum galectin-3 level in the PFAPA-attack group (1.025 ng/ml) was significantly lower than the levels in healthy control (2.367 ng/ml), streptococcal pharyngitis (3.021 ng/ml), FMF attack (2.402 ng/ml), and FMF-attack-free groups (2.797 ng/ml) (p = 0.006, 0.03, 0.01, and < 0.001, respectively). PFAPA-attack-free group had lower galectin-3 levels than the FMF-attack-free group (1.794 vs. 2.797 ng/ml, respectively; p = 0.01). Galectin-3 levels did not differ significantly between CAPS and attack-free PFAPA patients (1.439 ng/ml vs. 1.794 ng/ml, respectively; p = 0.63). In our study, for the first time, we defined galectin-3 as a promising biomarker that differs between PFAPA and FMF patients during both disease flares and attack-free periods. Further studies with high number of patients could validate its role as a biomarker.

CARD8 and IL1B Polymorphisms Influence MRI Brain Patterns in Newborns with Hypoxic-Ischemic Encephalopathy Treated with Hypothermia

Inflammation and oxidative stress are recognized as important contributors of brain injury in newborns due to a perinatal hypoxic-ischemic (HI) insult. Genetic variability in these pathways could influence the response to HI and the outcome of brain injury. The aim of our study was to evaluate the impact of common single-nucleotide polymorphisms in the genes involved in inflammation and response to oxidative stress on brain injury in newborns after perinatal HI insult based on the severity and pattern of magnetic resonance imaging (MRI) findings. The DNA of 44 subjects was isolated from buccal swabs. Genotyping was performed for NLRP3 rs35829419, CARD8 rs2043211, IL1B rs16944, IL1B rs1143623, IL1B rs1071676, TNF rs1800629, CAT rs1001179, SOD2 rs4880, and GPX1 rs1050450. Polymorphism in CARD8 was found to be protective against HI brain injury detected by MRI overall findings. Polymorphisms in IL1B were associated with posterior limb of internal capsule, basal ganglia, and white matter brain patterns determined by MRI. Our results suggest a possible association between genetic variability in inflammation- and antioxidant-related pathways and the severity of brain injury after HI insult in newborns.

A Novel DSP Truncating Variant in a Family with Episodic Myocardial Injury in the Course of Arrhythmogenic Cardiomyopathy-A Possible Role of a Low Penetrance NLRP3 Variant

Mono-allelic dominant mutations in the desmoplakin gene (DSP) have been linked to known cardiac disorders, such as arrhythmogenic right ventricular cardiomyopathy and dilated cardiomyopathy. During the course of DSP cardiomyopathy, episodes of acute myocardial injury may occur. While their mechanisms remain unclear, myocarditis has been postulated as an underlying cause. We report on an adolescent girl with arrhythmogenic biventricular cardiomyopathy and three acute myocarditis-like episodes in whom we found a novel truncating DSP variant accompanied by a known low penetrance R490K variant in the NLRP3. Upon family screening, other carriers of the DSP variant have been identified in whom only mild cardiac abnormalities were found. We hypothesized that the uncommon course of cardiomyopathy in the proband as well as striking discrepancies in the phenotype observed in her family may be explained by the co-existence of her low penetrance genetic autoinflammatory predisposition.

Increased Prevalence of NLRP3 Q703K Variant Among Patients With Autoinflammatory Diseases: An International Multicentric Study

Background: The NLRP3 inflammasome has been recognized as one of the key components of innate immunity. Gain-of-function mutations in the exon 3 of NLRP3 gene have been implicated in inflammatory diseases suggesting the presence of functionally important sites in this region. Q703K (c.2107C>A, p.Gln703Lys, also known in the literature as Q705K) is a common variant of NLRP3, that has been considered to be both clinically unremarkable or disease-causing with a reduced penetrance. Objectives: We aimed to investigate the potential genetic impact of the NLRP3 variant Q703K in patients with recurrent fever presenting with two autoinflammatory diseases: PFAPA (periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis) and CAPS (cryopyrin-associated periodic syndrome), as well as with undefined autoinflammatory disease (uAID). Methods: This is an international multicentric observational retrospective study characterizing the clinical phenotype of patients presenting with recurrent fever suspected to be of auto-inflammatory origin and where the Q703K NLRP3 variant was found. Monocytes of parents of 6 Q703K+ PFAPA patients were studied and levels of pro-inflammatory cytokines produced by monocytes of Q703K+ and Q703K- parents have been compared by ELISA. Results: We report 42 patients with the Q703K NLRP3 genetic variant: 21 were PFAPA patients, 6 had a CAPS phenotype, and 15 had an uAID. The phenotypes of PFAPA, CAPS and uAID were quite similar between Q703K positive and negative patients with the exception of increased prevalence of pharyngitis in the Q703K positive CAPS population compared to the negative one. The in vitro production of IL-1β was not significantly different between Q703K+ and Q703K- monocytes from asymptomatic parents. Conclusion: The evidence we report in our study shows an increased prevalence of NLRP3 Q703K in patients with autoinflammatory diseases, suggesting an association between the Q703K variant and the risk of PFAPA, CAPS and uAID syndromes. However, we did not show a functional effect of this mutation on the inflammasome basal activity.

Total saponin of Dioscorea collettii attenuates MSU crystal‑induced inflammation via inhibiting the activation of the NALP3 inflammasome and caspase‑1 in THP‑1 macrophages

Total saponins extracted from Dioscorea collettii (TSD), extracts of the Chinese herb Dioscorea, are thought to exhibit therapeutic benefit in gouty arthritis. However, its exact mechanism remains unclear. The current study aimed to elucidate the underlying mechanisms by investigating the effects of TSD on the inflammation induced by monosodium urate (MSU) crystals in THP-1 macrophages. The viability of THP-1 macrophages was examined using the MTT assay and the levels of inflammatory cytokines, including interleukin (IL)-1β, IL-18 and tumor necrosis factor (TNF)-α, released by the cells were quantitatively measured using ELISA kits. The results revealed that the protein level of cluster of differentiation 11b increased in THP-1 cells treated with 100 ng/ml phorbol ester, suggesting that monocytic THP-1 cells were successfully differentiated into macrophages. TSD decreased the levels of inflammatory cytokines, including TNF-α, IL-18 and IL-1β, secreted by THP-1 macrophages. As the release of IL-1β and IL-18 is dependent on the NLR family pyrin domain containing 3 (NALP3) inflammasome and caspase-1, the current study investigated the effect of TSD on the aforementioned proteins. The results revealed that TSD decreased the protein levels of NALP3 and apoptosis-associated speck-like, which serve important roles in the assembly of the NALP3 inflammasome. Furthermore, NALP3 inflammasome-related proteins were also decreased by TSD in rotenone induced THP-1 macrophages, TSD inhibited the activation of caspase-1 and rotenone-induced NALP3 inflammasome activation in THP-1 macrophages. The results obtained in the current study revealed that TSD attenuated MSU crystal-induced inflammation by inhibiting rotenone-induced activation of the NALP3 inflammasome and caspase-1, suggesting that these two proteins may be novel targets for the treatment of gouty arthritis.

Inhibition of integrin α5β1 ameliorates VEGF-induced retinal neovascularization and leakage by suppressing NLRP3 inflammasome signaling in a mouse model

PURPOSE

To assess the effect of inhibiting integrin α5β1 by ATN-161 on vascular endothelial growth factor (VEGF)-induced neovascularization (NV) and leakage causing retinal detachment in adult Tet/opsin/VEGF transgenic mice, and characterize the underlying mechanism of its function.

METHOD

Retinas from adult Tet/opsin/VEGF transgenic mice and human retinal endothelial cells (HRECs) exposed to VEGF (treated with ATN-161 or PBS) were used to carry out immunofluorescence, RT-PCR and western blot to examine expression levels of integrin α5β1 and the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome. Retinal frozen section analysis was used to assess NV and leakage causing retinal detachment.

RESULTS

In comparison to normal-treated mice, doxycycline-treated Tet/opsin/VEGF transgenic mice showed severe retinal detachment and higher integrin α5β1 expression. Furthermore, the retinal detachment was inhibited significantly by ATN-161. Additionally, ATN-161 treatment was associated with a conspicuous reduction in NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), cleaved caspase-1, and mature interleukin-1β expression levels in the retinas of Tet/opsin/VEGF transgenic mice treated with doxycycline as well as in HRECs exposed to VEGF.

CONCLUSION

ATN-161, an antagonist of integrin α5β1, is a promising treatment for retinal neovascularization (RNV), and its retinal protection role appears to take effect through inhibition of NLRP3 inflammasome activity.

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.

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.

The genetic polymorphism and expression profiles of NLRP3 inflammasome in patients with chronic myeloid leukemia

NLRP3 inflammasome has been recently reported as an important risk factor in the development of cancer. But the relationship between polymorphisms of NLRP3 inflammasome related genes and chronic myeloid leukemia (CML) is rarely reported. Therefore, the aim of the present study was to investigate the association of five genetic polymorphisms (NLRP3, IL-1β, IL-18, CARD8 and NF-κB) in 267 CML patients and 344 healthy controls. We found that the AT genotype of CARD8 (rs2043211) was significantly higher compared to TT genotype in high and intermediate risk CML patients. IL-1β (rs16944) polymorphism in early molecular response at 6 months was marginally different, with more GG and less AA genotype in BCR-ABL^IS >1% group. IL-18 (rs1946518) polymorphism was significantly different with more GG genotype in BCR-ABL^IS >1% group at 6 months. We also demonstrated that WBC count of newly diagnosed patients carrying AG genotype was significantly higher than that of GG or AA genotype of IL-1β (rs16944). The onset age of patients carrying ins/ins genotype of NF-κB (rs28362491) was significantly older than that of ins/del and del/del genotype. Moreover, IL-1β or NLRP3 mRNA expression was decreased and IL-18 mRNA expression was increased significantly in CML patients compared with controls. In conclusion, the genetic polymorphisms of NLRP3 inflammasome may be served as potential predictors for CML.

Mutational profile of rare variants in inflammasome-related genes in Behçet disease: A Next Generation Sequencing approach

Behçet's disease (BD) is an immune-mediated systemic disorder with a well-established association with HLA class I and other genes. BD has clinical overlap with many autoinflammatory diseases (AIDs). The aim of this study was to investigate the role of rare variants in seven genes involved in AIDs: CECR1, MEFV, MVK, NLRP3, NOD2, PSTPIP1 and TNFRSF1A using a next generation sequencing (NGS) approach in 355 BD patients. To check global association of each gene, 4 tests: SKAT, CollapseBt, C(α) and weighted KBAC were used. Databases: 1000 Genomes Project Phase 3, Infevers, HGMD and ClinVar and algorithms: PolyPhen2 and SIFT were consulted to collect information of the 62 variants found. All the genes resulted associated using SKAT but only 3 (MVK, NOD2 and PSTPIP1) with C(α) and weighted KBAC. When all the genes are considered, 40 variants were associated to AIDs in clinical databases and 25 were predicted as pathogenic at least by one of the algorithms. Including only MVK, NOD2 and PSTPIP1, the associated to AIDs variants found in BD were 20 and the predicted as pathogenic, 12. The maxima contribution corresponds to NOD2. This study supports influence of rare variants in genes involved in AIDs in the pathogenesis of BD.

Genetic Polymorphisms in Inflammasome-Dependent Innate Immunity among Pediatric Patients with Severe Renal Parenchymal Infections

Background

Inflammasome innate immune response activation has been demonstrated in various inflammatory diseases and microbial infections. However, to our knowledge, no study has examined the inflammasome-dependent pathways in patients with urinary tract infection. Defective or variant genes associated with innate immunity are believed to alter the host’s susceptibility to microbial infection. This study investigated genetic polymorphisms in genes encoding inflammasomes and the subsequent released cytokines in pediatric patients with severe renal parenchymal infections.

Methodology

This study included patients diagnosed with acute pyelonephritis (APN) and acute lobar nephronia (ALN) who had no underlying disease or structural anomalies other than vesicoureteral reflux (VUR). Single nucleotide polymorphism (SNP) genotyping was performed in the genes associated with inflammasome formation and activation (NLRP3, CARD8) and subsequent IL–1β cytokine generation (IL–1β).

Principal Findings

A total of 40 SNPs were selected for initial genotyping. Analysis of samples from 48 patients each and 96 controls revealed that only nine SNPs (five SNPs in NLRP3; three SNPs in CARD8; one SNP in IL–1β) had heterozygosity rates >0.01. Hardy–Weinberg equilibrium was satisfied for the observed genotype frequencies of these SNPs. Analysis excluding patients with VUR, a well-known risk factor for severe UTIs, revealed a lower frequency of the CC genotype in NLRP3 (rs4612666) in patients with APN and ALN than in controls. Correction for multiple-SNP testing showed that the non-VUR subgroup of the APN+ALN combined patient groups remained significantly different from the control group (P < 0.0055).

Conclusions

This study is the first to suggest that the inflammasome-dependent innate immunity pathway is associated with the pathogenesis of pediatric severe renal parenchymal infections. Further investigation is warranted to clarify its pathogenic mechanism.

The Association of CARD8 rs2043211 Polymorphism with Preeclampsia in the Chinese Han Population

OBJECTIVE

The purpose of our study was to investigate the association between polymorphism of rs2043211 in CARD8 and susceptibility to preeclampsia (PE) in the Chinese Han population.

METHODS

261 PE patients and 451 controls were genotyped for rs2043211 with the method of TaqMan allele discrimination assays. Clinical data were collected to perform genotype-phenotype analysis.

RESULTS

Our study suggested that the rs2043211 variant was associated with the development of PE in the Chinese Han population. The genotypic and allelic frequencies differed significantly between the two groups (x03C7;2 = 8.198, p = 0.017 by genotype; x03C7;2 = 6.741, p = 0.009 by allele). The T allele was the risk allele for predisposition to PE (OR = 1.331, 95% CI 1.072-1.652).

CONCLUSION

The polymorphism of rs2043211 in CARD8 may be a relevant host susceptibility factor for the development of PE in the Chinese Han population.

Genetic profiling of autoinflammatory disorders in patients with periodic fever: a prospective study

BACKGROUND

Periodic fever syndromes (PFS) are an emerging group of autoinflammatory disorders. Clinical overlap exists and multiple genetic analyses may be needed to assist diagnosis. We evaluated the diagnostic value of a 5-gene sequencing panel (5GP) in patients with undiagnosed PFS.

METHODS

Simultaneous double strand Sanger sequencing of MEFV, MVK, TNFRSF1A, NLRP3, NLRP12 genes was performed in 42 patients with unexplained PFS. Clinical features were correlated with genetic results.

RESULTS

None of 42 patients analyzed displayed a causative genotype. However, single or multiple genetic variants of uncertain significance were detected in 24 subjects. Only in 5 subjects a definite diagnosis was made by taking into account both genetic and clinical data (2 TRAPS syndrome; 2 FMF; 1 FCAS). Statistical analysis showed that patients carrying genetic variants in one or more of the five selected genes displayed a significantly lower response to glucocorticoids compared with subjects who had completely negative genetic results.

CONCLUSIONS

The sequencing of multiple genes is of little help in the diagnostics of PFS and can often lead to results of uncertain interpretation, thus the clinically driven sequencing of single genes should remain the recommended approach. However, the presence of single or multiple genetic variants of uncertain significance, even if not allowing any specific diagnosis, correlated with a poorer response to glucocorticoids, possibly indicating a multifactorial subgroup of PFS with differential response to pharmacological treatment.

A functional inflammasome activation assay differentiates patients with pathogenic NLRP3 mutations and symptomatic patients with low penetrance variants

Cryopyrin-associated periodic syndromes (CAPS) are characterized by recurrent episodes of systemic inflammation caused by mutations in the NLRP3 gene. Besides confirmed pathogenic NLRP3 mutations, patients with CAPS-like symptoms frequently show low penetrance variants in NLRP3. The disease relevance of these variants is inconsistent. In this study, we investigated if an inflammasome activation assay differentiates between patients with confirmed pathogenic CAPS mutations, patients with low penetrance NLRP3 variants (V198M and Q703K) and healthy controls. The release of mature IL-1β, IL-18, and caspase-1 into cell culture supernatants after 4h of inflammasome stimulation was significantly increased in patients with confirmed pathogenic CAPS mutations compared to low penetrance NLRP3 variants and controls. IL-1β secretion in CAPS patients correlated with disease severity. This inflammasome activation assay differentiates between autoinflammation patients with confirmed pathogenic CAPS mutations and patients with low penetrance NLRP3 variants, and points towards alternative pathophysiological mechanisms in low penetrance NLRP3 variants.

NLRP3 inflammasome sequential changes in Staphylococcus aureus-induced mouse model of acute rhinosinusitis

The NLR pyrin domain containing 3 (NLRP3) inflammasome plays a crucial role in lung disease and may have a similar role in upper respiratory tract inflammation. We therefore constructed a C57BL/6 mouse model of acute rhinosinusitis induced by Staphylococcus aureus and investigated the role of the NLRP3 inflammasome in this model. Mice were classified as non-inoculated group (group A) and inoculated groups (groups B, C, D and E, sacrificed 1, 3, 7 and 14 days after inoculation, respectively). Hematoxylin-eosin staining showed that each group had inflammatory cell infiltration, except group A. The damage of the nasal mucosa was aggravated gradually over time. Western blot and immunofluorescence showed that the structural proteins of the NLRP3 inflammasome (NLRP3, ASC (apoptosis-associated speck-like protein containing CARD), procaspase-1) in groups B, C, D and E were increased gradually. But they were reduced in group B compared with group A, except for NLRP3. Western blot showed that the cleavage fragment of procaspase-1, p20 in groups B, C, D and E was increased gradually. Real-time PCR showed that the corresponding mRNAs of the structural proteins were changed the same as their proteins. IL-1β mRNA and mature IL-1β protein were increased gradually in groups A, B, C, D and E. These results indicate that NLRP3 inflammasome activation was associated with the acute rhinosinusitis, and that there was a positive correlation between the expression level of the NLRP3 inflammasome and the severity of acute rhinosinusitis.

Anti-TNF treatment response in rheumatoid arthritis patients is associated with genetic variation in the NLRP3-inflammasome

OBJECTIVE

Many patients with rheumatoid arthritis (RA) benefit from tumor necrosis factor-α blocking treatment (anti-TNF), but about one third do not respond. The objective of this study was to replicate and extend previously found associations between anti-TNF treatment response and genetic variation in the TNF-, NF-κB- and pattern recognition receptor signalling pathways.

METHODS

Forty-one single nucleotide polymorphisms (SNPs), including 34 functional, in 28 genes involved in inflammatory pathways were assessed in 538 anti-TNF naive Danish RA patients with clinical data. Multivariable logistic regression analyses were performed to test associations between genotypes and treatment response at 3-6 months using the European League Against Rheumatism (EULAR) response criterion. American College of Rheumatology treatment response (ACR50) and relative change in 28-joint disease activity score (relDAS28) were used as secondary outcomes. Subgroup analyses were stratified according to smoking status, type of anti-TNF drug and IgM-Rheumatoid Factor (IgM-RF) status. False discovery rate (FDR) controlling was used to adjust for multiple testing.

RESULTS

Statistically significant associations with EULAR response were found for two SNPs in NLRP3(rs4612666) (OR (odds ratio) for good/moderate response = 0.64 (95% confidence interval: 0.44-0.95), p = 0.025, q = 0.95) and INFG(rs2430561) (OR = 0.40 (0.21-0.76), p = 0.005, q = 0.18) and among IgM-RF positive patients for TNFRS1A(rs4149570) (0.59 (0.36-0.98), p = 0.040, q = 0.76). Current smokers who carried the NLRP3(rs4612666) variant allele were less likely to benefit from anti-TNF treatment (OR = 0.24 (0.10-0.56), p = 0.001, q = 0.04).

CONCLUSIONS

In a population of Danish RA patients, we confirm the NLRP3 gene as associated with EULAR anti-TNF response as previously reported. The NLRP3 variant (T) allele is associated with lower treatment response, in particular among current smokers. Furthermore, we find that a functional polymorphism in the interferon-γ gene is associated with anti-TNF response. All findings should be tested by replication in independent validation cohorts and augmented by assessing cytokine levels and activities of the relevant gene products.

Chrysophanol inhibits NALP3 inflammasome activation and ameliorates cerebral ischemia/reperfusion in mice

The most effective way to contain cerebral ischemic injury is reperfusion; however, reperfusion itself may result in tissue injury, for which inflammatory damage is one of the main causative factors. NALP3 inflammasome is a multiprotein complex. It consists of NALP3, ASC, and caspase-1, whose function is to switch on the inflammatory process. Chrysophanol is an extract from plants of Rheum genus and it possesses many pharmacological effects including its anti-inflammation activity. In this study, the effects of chrysophanol in cerebral ischemia/reperfusion and the potential mechanisms were investigated. Male CD1 mice were subject to transient middle cerebral artery occlusion (tMCAO). The NALP3 inflammasome activation status and its dynamic expression during the natural inflammatory response induced by tMCAO were first profiled. The neuroprotective effects of chrysophanol were then assessed and the potential mechanisms mediating the observed neuroprotection were then explored. Physical parameters including neurological deficit, infarct size, brain edema, and BBB permeability were measured at 24 h after tMCAO. Confocal microscopy, Western blotting, immunohistochemistry, and qRT-PCR techniques were utilized to analyze the expression of NALP3 inflammasome and IL-1β. Our results indicated that the brain tissue damage during cerebral ischemia/reperfusion is accompanied by NALP3 inflammasome activation. Chrysophanol could inhibit the activation of NALP3 inflammasome and protect cerebral ischemic stroke.

C10X polymorphism in the CARD8 gene is associated with bacteraemia

The NLRP3 inflammasome is an intracellular multi-protein complex that triggers caspase-1 mediated maturation of interleukin-1β (IL-1β); one of the most potent mediators of inflammation and a major cytokine produced during severe infections, like sepsis. However, the excessive cytokine levels seem to stage for tissue injury and organ failure, and high levels of IL-1β correlates with severity and mortality of sepsis. Instead, recent data suggest caspase-1 to function as a guardian against severe infections. CARD8 has been implied to regulate the synthesis of IL-1β via interaction to caspase-1. In recent years, polymorphism of CARD8 (C10X) per se or in combination with NLRP3 (Q705K) has been implicated with increased risk of inflammation. The aim was to investigate the correlation of these polymorphisms with severe blood stream infection. Human DNA was extracted from blood culture bottles that were found to be positive for microbial growth (i.e. patients with bacteraemia). Polymorphisms Q705K in the NLRP3 gene and C10X in the CARD8 gene were genotyped using TaqMan genotyping assay. The results were compared to healthy controls and to samples from patients with negative cultures. The polymorphism C10X was significantly over-represented among patients with bacteraemia as compared to healthy controls, whereas patients with negative blood culture were not associated with a higher prevalence. No association was observed with polymorphism Q705K of NLRP3 in either group of patients. Patients carrying polymorphism C10X in the CARD8 gene are at increased risk of developing bacteraemia and severe inflammation.

In vitro effects of emodin on peritoneal macrophages that express membrane-bound CD14 protein in a rat model of severe acute pancreatitis/systemic inflammatory response syndrome

Emodin is the main active constituent of rhubarb and is often used in Chinese herbal medicine for the treatment of systemic inflammatory response syndrome (SIRS). The present study aimed to determine the in vitro effects of emodin on the expression of membrane-bound cluster of differentiation 14 (mCD14) protein in peritoneal macrophages (pMΦs). The severe acute pancreatitis (SAP)̸SIRS model was established in Sprague‑Dawley (SD) rats via retrograde injection of 1.5% sodium deoxycholate into the common biliopancreatic duct. The 40 SD rats were randomly divided into the sham‑operated (n=10) group (SO) and the model group (n=30). After 24 h, pMΦs were harvested and the model group was randomly divided into three subgroups (n=10 per group), the 5 µg/ml emodin group (EMO), the 0.1 µmol/ml dexamethasone group (DEX) and the SIRS/SAP group (SI). Treatment agents were administered following macrophage adhesion for 24 h. Compared with that of the SO group, the SI group showed significantly increased pathological changes (P<0.01). Compared with that of the SO group, mCD14 expression in pMΦs was significantly decreased in the SI group (P<0.01). Additionally, compared with that of the SI group, mCD14 expression in pMΦs was significantly increased in the EMO group (P<0.01) and in the DEX group (P<0.01). Compared with that of the DEX group, mCD14 expression in pMΦs was significantly increased in the EMO group (25.60±2.79 vs. 20.87±1.99; P<0.01). The pathological changes observed in the pancreas of rats in the model groups were more severe than that of the SO group. Moreover, mCD14 expression levels in pMΦs were significantly decreased in the SI group. The pathological changes of each intervention group improved to various degrees, particularly in the EMO group.

Kinase AKT controls innate immune cell development and function

The critical roles of kinase AKT in tumour cell proliferation, apoptosis and protein synthesis have been widely recognized. But AKT also plays an important role in immune modulation. Recent studies have confirmed that kinase AKT can regulate the development and functions of innate immune cells (neutrophil, macrophage and dendritic cell). Studies have shown that different isoforms of kinase AKT have different effects in regulating immunity-related diseases, mainly through the mammalian target of rapamycin-dependent or -independent pathways. The purpose of this review is to illustrate the immune modulating effects of kinase AKT on innate immune cell development, survival and function.

Cytokine profile in a cohort of healthy blood donors carrying polymorphisms in genes encoding the NLRP3 inflammasome

Background

The NLRP3 inflammasome has been recognized as one of the key components of the innate immunity by sensing a diversity of insults. Inflammasome activation results in the maturation of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18. Increased production of IL-1β is found in patients with gain-of-function polymorphisms in genes encoding the NLRP3 inflammasome. Since approximately 5% of the Swedish population are heterozygote carriers of these combined gene variants, their impact on inflammasome status and a relationship on disease development is therefore highly relevant to study. The present study investigates levels of inflammasome-produced cytokines as a measure of inflammasome activation in healthy individuals carrying Q705K polymorphism in the NLRP3 gene combined with C10X in the CARD8 gene.

Materials and Methods

Genotyping of 1006 healthy blood donors was performed for the polymorphisms Q705K in the NLRP3 and C10X in the CARD8 genes. IL-1β, IL-18, IL-33, as well as a number of other pro-inflammatory cytokines, were analyzed by Luminex or ELISA in plasma from individuals carrying the polymorphisms and in age and gender matched non-carrier controls.

Results & Discussion

The prevalence of the polymorphisms was in line with previous studies. Plasma levels of IL-1β and IL-33 were elevated among carriers of combined Q705K+C10X polymorphisms compared to controls, whereas no difference was found for IL-18 and the other cytokines measured. Moreover, carriers of C10X or Q705K perse had similar plasma levels of IL-1β as non-carriers. These data suggest that the combined polymorphisms create inflammasomes with increased basal activation state, which might provide a more favourable innate immune response. In spite of this, it could also represent the mechanisms by which the inflammatory loop is triggered into a long-term inflammatory phenotype.

In vitro effects of emodin on peritoneal macrophage intercellular adhesion molecule-3 in a rat model of severe acute pancreatitis/systemic inflammatory response syndrome

Rhubarb is often used in Chinese herbal medicine for the treatment of systemic inflammatory response syndrome (SIRS). Emodin is the main active constituent of rhubarb. This study was performed to investigate the in vitro effects of emodin and dexamethasone on peritoneal macrophage (pMΦ) phagocytosis and the expression of intercellular adhesion molecule-3 (ICAM-3). A total of 40 Sprague-Dawley (SD) rats were randomly divided into sham surgery (n=10) and model groups (n=30). After 24 h, pMΦs were harvested and the model group was randomly divided into three subgroups (n=10 rats/subgroup): the 5 μg/ml emodin, 0.1 μmol/ml dexamethasone and control groups. The drugs were administered following macrophage (MΦ) adhesion for 24 h. pMΦ phagocytosis was significantly increased in the emodin group compared to that in the control group. Moreover, pMΦ phagocytosis was significantly increased in the emodin group compared to that in the dexamethasone group. The expression of ICAM-3 was significantly increased in the emodin group compared to that in the control group. The expression of ICAM-3 was significantly increased in the emodin group compared to that in the dexamethasone group. The expression of ICAM-3 was significantly increased in the emodin and dexamethasone groups compared to that in the control group. pMΦ phagocytosis and ICAM-3 expression were significantly increased following emodin treatment compared to those in the control and dexamethasone groups, indicating that emodin may enhance pMΦ phagocytosis and apoptotic cell clearance by altering ICAM-3 expression.

Regulation of neutrophil apoptosis differs after in vivo transmigration to skin chambers and synovial fluid: a role for inflammasome-dependent interleukin-1β release

Short-lived neutrophils are major players in inflammation, arriving early to infected and/or injured tissues. After performed duty, neutrophils are programmed to die by apoptosis and are thereafter rapidly cleared by other phagocytes. In vitro, modulation of the apoptotic process has been thoroughly investigated in neutrophils isolated from peripheral blood, but less is known about the regulation of this process in neutrophils derived from extravascular tissues. We recently demonstrated that neutrophils having transmigrated in vivo, obtained from experimental skin chambers of healthy human subjects, are resistant to the death-delaying signals induced by a range of antiapoptotic stimuli. In the current study, we show that skin chamber neutrophils spontaneously secrete high levels of antiapoptotic interleukin (IL)-1β which delays neutrophil apoptosis. Contrary to skin chamber fluid, synovial fluid from patients with rheumatic arthritis contained only moderate levels of IL-1β, and neutrophils taken from this site were fully responsive to antiapoptotic stimulation during in vitro culture. Our data demonstrate that resistance to antiapoptotic stimulation is not a general feature of tissue neutrophils and imply that autocrine IL-1β signaling could be an important factor in determining how life and death of neutrophils is regulated in inflamed tissues.

Increased apoptosis of peripheral blood neutrophils is associated with reduced incidence of infection in trauma patients with hemorrhagic shock

OBJECTIVE

We aimed to describe the relationship between early peripheral leukocyte apoptosis and incidence of subsequent infection in trauma patients with hemorrhagic shock (T/HS).

METHODS

T/HS patients requiring emergency surgery were prospectively enrolled. Nucleosome ELISA and TUNEL staining were performed on peripheral blood drawn pre-operatively, post-operatively and at 24 h. Subjects were followed for 30 days or until death or hospital discharge to record all episodes of infection.

RESULTS

Forty-one subjects were enrolled. Six died within 24 h of surgery and were not included in the analysis. Nucleosome levels peaked post-operatively and dropped to baseline levels at 24 h (p = 0.03). TUNEL analysis revealed that polymorphonuclear neutrophils (PMNs) accounted for 72% of apoptotic leukocytes; the remaining apoptotic cells were mainly lymphocytes. Increased post-operative leukocyte apoptosis was associated with decreased systemic inflammatory response syndrome (SIRS) severity. Seventeen of the 35 survivors (48.6%) developed infections, while 18 (51.4%) did not. Pre-operative and post-operative nucleosome levels were 2.5 and 3 times higher, respectively, in T/HS patients who did not develop infection compared to those who did. Increased nucleosome levels were associated in particular with protection against sepsis (p=0.03) and multiple infections (p = 0.01).

CONCLUSION

Peripheral blood PMN apoptosis in the early resuscitative period is associated with decreased incidence of subsequent infection in T/HS patients.

Francisella tularensis alters human neutrophil gene expression: insights into the molecular basis of delayed neutrophil apoptosis

We demonstrated recently that Francisella tularensis profoundly impairs human neutrophil apoptosis, but how this is achieved is largely unknown. Herein we used human oligonucleotide microarrays to test the hypothesis that changes in neutrophil gene expression contribute to this phenotype, and now demonstrate that F. tularensis live vaccine strain (LVS) caused significant changes in neutrophil gene expression over a 24-hour time period relative to the uninfected controls. Of approximately 47,000 genes analyzed, 3,435 were significantly up- or downregulated by LVS, including 365 unique genes associated with apoptosis and cell survival. Specific targets in this category included genes asso-ciated with the intrinsic and extrinsic apoptotic pathways (CFLAR, TNFAIP3, TNFRSF10D, SOD2, BCL2A1, BIRC4, PIM2, TNFSF10, TNFRSF10C, CASP2 and CASP8) and genes that act via the NFĸB pathway and other mechanisms to prolong cell viability (NFKB1, NFKB2 and RELA, IL1B, CAST, CDK2,GADD45B, BCL3, BIRC3, CDK2, IL1A, PBEF1, IL6, CXCL1, CCL4 and VEGF). The microarray data were confirmed by qPCR and pathway analysis. Moreover, we demonstrate that the X-linked inhibitor of apoptosis protein remained abundant in polymorphonuclear leukocytes over 48 h of LVS infection, whereas BAX mRNA and protein were progressively downregulated. These data strongly suggest that antiapoptotic and prosurvival mechanisms collaborate to sustain the viability of F. tularensis--infected neutrophils.