A gain-of-function NLRP3 3′-UTR polymorphism causes miR-146a-mediated suppression of NLRP3 expression and confers protection against sepsis progression

Abstract

Nucleotide-binding domain and leucine-rich repeat (LRR)-containing family protein 3 (NLRP3) regulated the maturation of inflammation-related cytokines by forming NLRP3 inflammasome, which plays pivotal roles in sepsis pathogenesis. In this study, we evaluated the genetic association of NLRP3 polymorphisms with sepsis (640 patients and 769 controls) and characterized the impact of NLRP3 polymorphisms on NLRP3 expression and inflammatory responses. No significant differences were observed in genotype/allelic frequencies of NLRP3 29940G>C between sepsis cases and controls. The G allele was significantly overrepresented in patients with septic shock than those in sepsis subgroup, and the GC/GG genetypes were related to the 28-day mortality of sepsis. Lipopolysaccharide challenge to peripheral blood mononuclear cells showed a significant suppression of NLRP3 mRNA expression and release of IL-1β and TNF-α in CC compared with the GC/GG genotype category. Functional experiments with luciferase reporter vectors containing the NLRP3 3′-UTR with the 29940 G-to-C variation in HUVECs and THP-1 cells showed a potential suppressive effect of miR-146a on NLRP3 transcription in the presence of the C allele. Taken together, these results demonstrated that the 29940 G-to-C mutation within the NLRP3 3′-UTR was a gain-of-function alteration that caused the suppression of NLRP3 expression and downstream inflammatory cytokine production via binding with miR-146a, which ultimately protected patients against susceptibility to sepsis progression and poor clinical outcome.

Investigation of Association of Complement 5 Genetic Polymorphisms with Sepsis and Sepsis-Induced Inflammatory Responses

“…Two C5 genetic SNPs, rs17611 and rs2269067, were genotyped with an iMLDRTM multiple SNP typing kit (Shanghai Tianhao Biotechnology Co., Ltd.), according to our previous studies. 5 In addition, 10% of the samples were randomly selected as an independent validation group for regenotyping to monitor genotyping quality. Final analysis of the experimental data was performed on GeneMapper 4.1 (Applied Biosystems, Carlsbad, CA, USA).…”

“…30 Healthy controls and patients with sepsis were excluded if they met the exclusion criteria described in our previous studies. [5][6][7] Two milliliters of peripheral venous blood from the enrolled subjects was collected into an ethylene-diamine tetraacetic acid-containing tube for SNP genotyping within the first 12 h of sepsis diagnosis. Peripheral blood mononuclear cells (PBMCs) and plasma were extracted from the peripheral venous blood and stored separately at −80 °C until analysis.…”

“…3,4 As the most common type of genetic heterogeneity in humans, single nucleotide polymorphisms (SNPs) in genes encoding inflammatory cytokines, such as NLRP3, MCP-1 and IL-27, are associated with sepsis outcomes. [5][6][7] Therefore, the identification and quantification of functional genetic variants associated with sepsis will help to exploit new genetic diagnostic and therapeutic approaches, which will improve the prognosis of patients who are susceptible to sepsis.…”

Bacteria and Sepsis: Microbiome to the Rescue?

“…However, NLRP3 can be activated by common culprit Gram-positive and Gram-negative bacteria found in septic patients such as Staphylococcus aureus and Streptococcus pneumoniae [46][47][48]. Interestingly, polymorphisms of the NLPR3 gene have been demonstrated to impart gain-offunction that resulted in a suppression of NLRP3 expression and downstream inflammatory activation, which resulted in protection of patients from progression of sepsis [49].…”

The Impact of NLRP3 Activation on Hematopoietic Stem Cell Transplantation

“…Interestingly, a recent study showed that the G/G genotype of rs10754558 was significantly associated with increased risk of developing septic shock compared to the controls, and mechanistic studies utilizing luciferase reporter vectors containing NLRP3 3′-UTR with the rs10754558 variation showed that the allele C had a higher affinity to miR-146a, a negative regulator of NLRP3 transcripts and, consequently, the allele C of rs10754558 was more sensitive to the suppressive effects of miR-146a than the allele G [75]. These results further validated the functional relevance of rs10754558 and established the molecular bases by which a genetic variant in the 3′-UTR of the NLRP3 gene regulates NLRP3 expression, where a gain-of-function alteration (allele G) augments the resistance of NLRP3 transcripts to the suppressive regulatory effects of miR-146a-5p (Figure 2).…”