The P2X7 loss-of-function Glu496Ala polymorphism affects ex vivo cytokine release and protects against the cytotoxic effects of high ATP-levels

Abstract

BackgroundThe P2X7 receptor plays an important role in cytokine release during the inflammatory response in vivo. Polymorphisms within the P2X7 receptor gene that lead to loss of receptor function may contribute to impaired cytokine release by immune cells. Therefore, we investigated whether a known loss-of-function polymorphism (Glu496Ala) in the P2X7 receptor gene leads to alterations in cytokine release in response to ATP.ResultsAn ex vivo whole blood model was used to induce an inflammatory reaction with the pro-inflammatory stimuli LPS and PHA (phytohemagglutinin). Blood from n=9 subjects with the Glu496Ala P2X7 SNP (P2X7MUT) and n=7 ‘wild-type’ subjects (no P2X7 SNP; P2X7WT) was used.Addition of ATP (0.9-3 mM) to LPS/PHA-stimulated whole blood induced an increase in IL-1β release in P2X7MUT subjects, whereas decreased release was observed in P2X7WT subjects. Decreased levels of IL-6 and TNF-α in response to ATP were shown in both P2X7MUT and P2X7WT subjects, which was less pronounced in P2X7MUT subjects. ATP at 3 mM also significantly decreased levels of lactate dehydrogenase (LDH) in P2X7MUT subjects compared to P2X7WT subjects.ConclusionsThe presence of the non-synonymous Glu496Ala loss-of-function polymorphism within the P2X7 receptor gene is likely to be of importance in the release of cytokines during inflammation. Furthermore, this study suggests that carriers of the Glu496Ala loss-of-function polymorphism are protected against the cytotoxic effects of high ATP-levels.

Association of P2RX7 functional variants with localized aggressive periodontitis

“…A SNP in the same exon, rs2230911, encodes a partial loss‐of‐function allele at residue 357 (G ‐ serine), which is in the intracellular carboxy terminus, in an area that may bind beta‐arrestin‐2. The fourth SNP analysed is at codon 496, rs3751143, whose loss‐of‐function C allele encodes alanine, causing delay in receptor activity that cannot be rescued by the either of the two gain‐of‐function alleles in cis . Further, this C allele at codon 496 can also synergize with the 357 loss‐of‐function allele (G) in cis to produce a virtually null allele.…”

“…We investigated the possible contribution of P2RX7 to LAP because this leucocyte-ex- activity that cannot be rescued by the either of the two gain-offunction alleles in cis. 30,31 Further, this C allele at codon 496 can also synergize with the 357 loss-of-function allele (G) in cis to produce a virtually null allele. Only one individual SNP showed significant association (rs1718119), and that was by use of stepwise logistic regression, not chi-squared analysis.…”

P2X7 receptor polymorphisms do not influence endothelial function and vascular tone in neo-diagnosed, treatment-naive essential hypertensive patients

“…Recent, intriguing reports seem to suggest a role of P2X 7 R polymorphisms in modulating the clinical phenotype or the predisposition to develop different human diseases, from tuberculosis to transmission of chronic pain and mood disorders [31][32][33]. However, few reports have so far addressed the relationship between P2X 7 R gene and common cardiovascular diseases, such as hypertension, in clinical settings [18,19]. In these studies, IMT was used as a surrogate marker of atherosclerosis and arterial involvement.…”

“…The gene encoding for P2X 7 R is highly polymorphic; several nonsynonymous polymorphisms have been identified in the coding region, and some of these influence receptor function [17,18].…”

Association of Hypomorphic P2X7 Receptor Genotype With Age

“…P2RX7 is a highly polymorphic gene located on chromosome 12q24.31. The most studied P2RX7 single nucleotide polymorphism (SNP) is the 1513A>C. Homozygous subjects carrying the 1513CC genotype show a non-functional P2X7R pore and a reduced ability to activate inflammation compared to wild-type subjects bearing the AA genotype (Wesselius et al, 2012). The possible association of the 1513CC P2RX7 genotype with different inflammatory conditions is attracting increasing interest (Di Virgilio et al, 2017).…”