P2X7R Gene Research Articles

Non-aromatizable androgens modulate the lipopolysaccharide induced expression of the P2X7 receptor in human adipocytes.

Introduction: The activation of the P2X7 receptor subtype (P2X7R) has a main role in orchestrating the cellular inflammatory response in many different tissues. Obesity is characterized by dysfunctional fat deposition leading to a tissue-specific and systemic low-grade inflammation. Androgens and estrogens contribute to the whole adipose tissue inflammatory state, but the involvement of sex steroids in the purinergic signaling modulation in adipocytes is still unknown. Methods: We performed an in vitro study to evaluate the possible role of sex hormones on the P2X7R gene expression in human adipocytes, at baseline and after stimulation with bacterial lipopolysaccharide (LPS). We evaluated P2X7R gene expression during in vitro differentiation of human adipocytes, in the absence and presence of testosterone (T) and 17β-estradiol (E2) in the presence and absence of LPS. Furthermore, we analyzed the effects of incubation with dihydrotestosterone (DHT), a non-aromatizable androgen, using the co-incubation of isolated human adipocytes with T alone or in combination with anastrozole, an inhibitor of aromatase, the enzyme responsible of T conversion to E2. Results: At baseline, incubation of adipocytes with T or E2 did not significantly affect P2X7R gene expression. On the contrary, the incubation with DHT was associated with a significant reduction of P2X7R gene expression. LPS incubation significantly increased gene expression of P2X7R with respect to baseline. Interestingly, after LPS stimulation, DHT exposure showed an additional effect, markedly increasing the P2X7R gene expression. This amplificatory effect was confirmed by the incubation of adipocytes to both anastrozole and testosterone. In these experimental conditions, while no effect was observed at baseline, an amplification of the expression of the P2X7R mRNA was observed after stimulation with LPS. Discussion: The purinergic system is involved in the inflammatory response of adipocytes, and androgens may modulate its activity. In particular DHT, a non-aromatizable androgen, amplifies the LPS-induced P2X7R gene expression in human adipocytes thus showing a gender regulated response of the expression of this purinergic receptor strongly involved in the inflammatory response in adipose tissue.

Variation along P2RX7 interacts with early traumas on severity of anxiety suggesting a role for neuroinflammation

Emotional stress is a leading risk factor in the development of neuropsychiatric disorders possibly via immune activation. P2X7 receptors promote neuroinflammation, and research suggests a relationship between chromosome region 12q2431, in which the P2X7R gene is located, and development of mood disorders, however, few studies concentrate on its association with anxiety. Our aim was to investigate the effects of P2RX7 variation in interaction with early childhood traumas and recent stressors on anxiety. 1752 participants completed questionnaires assessing childhood adversities and recent negative life events, provided data on anxiety using the Brief Symptom Inventory, and were genotyped for 681 SNPs in the P2RX7 gene, 335 of which passed quality control and were entered into linear regression models followed by a linkage disequilibrium-based clumping procedure to identify clumps of SNPs with a significant main or interaction effect. We identified a significant clump with top SNP rs67881993 and containing a set of 29SNPs that are in high LD, which significantly interacted with early childhood traumas but not with recent stress conveying a protective effect against increased anxiety in those exposed to early adversities. Our study demonstrated that P2RX7 variants interact with distal and more etiological stressors in influencing the severity of anxiety symptoms, supporting previous scarce results and demonstrating its role in moderating the effects of stress.

Effect of extracellular adenosine triphosphate hydrolysis by apyrase on bleomycin-induced circulating and alveolar mononuclear phagocyte activation and lung inflammation.

Effect of extracellular adenosine triphosphate hydrolysis by apyrase on bleomycin-induced circulating and alveolar mononuclear phagocyte activation and lung inflammation.

Probenecid induces the recovery of renal ischemia/reperfusion injury via the blockade of Pannexin 1/P2X7 receptor axis

Renal ischemia/reperfusion injury (RI/RI) is one of the main driving causes of acute kidney injury. However, effective treatment to limit injury and promote recovery and/or survival is still unavailable. Probenecid (PBN), a drug indicated for refractory gout, exhibits protective activities against several preclinical diseases including cerebral and myocardial I/RI via Pannexin 1 (Panx1) and P2X7 receptors' (P2X7R) inhibition. However, its protective role against RI/RI has not been previously addressed. Accordingly, we subjected rats to bilateral RI/RI with/or without PBN treatment. Twenty-four hours post-reperfusion, PBN showed mild tubular injury and reduced serum nephrotoxicity indices, gene and protein expression levels of Panx 1 and P2X7R, and ATP and pro-inflammatory cytokines' levels. The nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome signaling was also downregulated, as demonstrated by reduced gene and protein expression of NLRP3 and caspase-1, along with suppressed IL-1β maturation. Furthermore, PBN enhanced Tregs activity as indicated by elevated FoxP3 gene expression, IL-10, and TGF-β renal levels. On day 5 post-reperfusion, PBN noticeably enhanced renal recovery, as demonstrated by intact tubular epithelium and restored nephrotoxicity indices, Panx 1 and P2X7R gene and protein expression levels, ATP and pro-inflammatory cytokine levels, and NLRP3 inflammasome signaling. Besides, renal Tregs activity was also significantly increased. Our study elaborates for the first time the effectiveness of PBN in recovering post-ischemic renal injury through synergistic inhibition in Panx1/P2X7R axis leading to inactivation of NLRP3 inflammasome signaling and activation of Tregs in ischemic renal tissues. Therefore, PBN can be considered a promising drug for RI/RI treatment.

Increased NLRP3 inflammasome expression in peripheral blood mononuclear cells of patients with schizophrenia: a case-control study

Objective This study aimed to evaluate the gene expression of the P2X purinoceptor 7 (P2X7R)- nod-like receptor pyrin domain-containing protein 3 (NLRP3) signal pathway in peripheral blood mononuclear cells (PBMCs) between schizophrenia (SCZ) patients and healthy controls (HC) to reveal its relationship with clinical variables. Methods Thirty-two SCZ patients and 41 healthy controls were included in this study. The Scale for the Assessment of Positive Symptoms (SAPS) and the Scale for the Assessment of Negative Symptoms (SANS), The Global Assessment of Functioning (GAF) scale and the Functioning Assessment Short Test (FAST) scales were applied. P2X7R, NLRP3, IL-1β and IL-18 gene expression levels were evaluated by real-time polymerase chain reaction in PBMCs. Results NLRP3, P2RX7, IL-1β and IL-18 expression levels were significantly higher in PBMCs of SCZ patients than in HC subjects. Negative correlations were found between NLRP3 gene expression levels and GAF and FAST scales scores. There was a negative correlation between IL-18 expression levels and the GAF and FAST scales scores and a positive correlation with the SAPS scale scores. Conclusions Systemic inflammation is implicated in SCZ pathogenesis, according to our findings, which suggest that the NLRP3 pathway may be involved. The NLRP3 inflammasome may serve as a biomarker for SCZ, and its pharmacological regulation may be a promising treatment approach. Key points We hypothesised that the NLRP3 pathway may contribute to the etiopathogenesis of schizophrenia. NLRP3, IL-1β and IL-18 mRNA levels were higher in patients with schizophrenia compared to healthy controls. Negative correlations were found between NLRP3 gene expression levels and GAF and FAST scales scores. There was a negative correlation between IL-18 expression levels and the GAF and FAST scales scores. The SAPS scale scores and IL-18 expression levels had a positive correlation. Given all these findings, it can be stated that NLRP3 inflammasome may play a role in the pathogenesis and symptoms of schizophrenia.

Blocking of P2X7r Reduces Mitochondrial Stress Induced by Alcohol and Electronic Cigarette Exposure in Brain Microvascular Endothelial Cells.

Studies in both humans and animal models demonstrated that chronic alcohol/e-cigarette (e-Cig) exposure affects mitochondrial function and impairs barrier function in brain microvascular endothelial cells (BMVECs). Identification of the signaling pathways by which chronic alcohol/e-Cig exposure induces mitochondrial damage in BMVEC is vital for protection of the blood–brain barrier (BBB). To address the issue, we treated human BMVEC [hBMVECs (D3 cell-line)] with ethanol (ETH) [100 mM], acetaldehyde (ALD) [100 μM], or e-cigarette (e-Cig) [35 ng/mL of 1.8% or 0% nicotine] conditioned medium and showed reduced mitochondrial oxidative phosphorylation (OXPHOS) measured by a Seahorse analyzer. Seahorse data were further complemented with the expression of mitochondrial OXPHOS proteins detected by Western blots. We also observed cytosolic escape of ATP and its extracellular release due to the disruption of mitochondrial membrane potential caused by ETH, ALD, or 1.8% e-Cig exposure. Moreover ETH, ALD, or 1.8% e-Cig treatment resulted in elevated purinergic P2X7r and TRPV1 channel gene expression, measured using qPCR. We also demonstrated the protective role of P2X7r antagonist A804598 (10 μM) in restoring mitochondrial oxidative phosphorylation levels and preventing extracellular ATP release. In a BBB functional assay using trans-endothelial electrical resistance, we showed that blocking the P2X7r channel enhanced barrier function. In summary, we identified the potential common pathways of mitochondrial injury caused by ETH, ALD, and 1.8% e-Cig which allow new protective interventions. We are further investigating the potential link between P2X7 regulatory pathways and mitochondrial health.

Bone phenotype of P2X4 receptor knockout mice: implication of a P2X7 receptor mutation?

Transgenic and knockout animal models are widely used to investigate the role of receptors, signaling pathways, and other peptides and proteins. Varying results are often published on the same model from different groups, and much effort has been put into understanding the underlying causes of these sometimes conflicting results. Recently, it has been shown that a P2X4R knockout model carries a so-called passenger mutation in the P2X7R gene, potentially affecting the interpretation of results from studies using this animal model. We therefore report this case to raise awareness about the potential pitfalls using genetically modified animal models, especially within P2 receptor research. Although purinergic signaling has been recognized as an important contributor to the regulation of bone remodeling, the process that maintains the bone quality during life, little is known about the role of the P2X4 receptor (P2X4R) in regulation of bone remodeling in health and disease. To address this, we analyzed the bone phenotype of P2rx4tm1Rass (C57BL/6J) knockout mice and corresponding wildtype using microCT and biomechanical testing. Overall, we found that the P2X4R knockout mice displayed improved bone microstructure and stronger bones in an age- and gender-dependent manner. While cortical BMD, trabecular BMD, and bone volume were higher in the 6-month-old females and 3-month-old males, this was not the case for the 3-month-old females and the 6-month-old males. Bone strength was only affected in the females. Moreover, we found that P2X4R KO mice carried the P2X7 receptor 451P wildtype allele, whereas the wildtype mice carried the 451L mutant allele. In conclusion, this study suggests that P2X4R could play a role in bone remodeling, but more importantly, it underlines the potential pitfalls when using knockout models and highlights the importance of interpreting results with great caution. Further studies are needed to verify any specific effects of P2X4R on bone metabolism.

Genetic variation of rs7958311 in P2X7R gene is associated with the susceptibility and disease activity of ankylosing spondylitis

ObjectivesTo describe association between the genetic variation of inflammation-associated gene, P2X7R, and ankylosing spondylitis (AS) susceptibility.MethodsFour single nucleotide polymorphisms (SNPs) of P2X7R gene were genotyped in 673 patients with AS...

Hypermethylation downregulates P2X7 receptor expression in astrocytoma.

The present study investigated the altered expression of p2X purinoceptor (P2X7R) in astrocytoma. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were used to determine the P2X7R expression in glioblastoma (GBM) and surrounding normal brain tissue. DNA methylation levels of P2X7R gene promoter in GBM were analyzed using a Sequenom MassARRAY® System. Immunohistochemistry (IHC) was used to detect the expression of P2X7R in astrocytoma at different malignancy grades, including diffuse astrocytoma, anaplastic astrocytoma and GBM. P2X7R mRNA and protein were significantly decreased in GBM compared with normal brain tissues. IHC results showed a negative correlation between P2X7R expression and tumor grade. The decreased P2X7R expression was mostly attributed to hypermethylation of its promoter. Therefore, P2X7R was found to perform an important role in tumorigenesis and progression of astrocytoma.

Calcium supplementation decreases BCP-induced inflammatory processes in blood cells through the NLRP3 inflammasome down-regulation.

Although scaffolds and biomaterials unavoidably come into direct contact with blood during bone defect filling, whole blood-biomaterials interactions have been poorly explored. By studying in 3D the interactions between biphasic calcium phosphate (BCP) in microparticulate form and blood, we showed for the first time that calcium supplementation of BCP microparticles (BCP/Ca) has anti-inflammatory properties compared to BCP-induced inflammation in whole blood cells and provided information related to the molecular mechanisms involved. The present study also showed that BCP, as well as BCP/Ca particles stimulate monocyte proliferation. As monocytes represent a powerful target for regenerative therapies and as an excessive inflammation limits the performance of biomaterials in bone tissue engineering, our results might have great implications to improve bone reconstruction.

P2X7 Receptor and APOE Polymorphisms and Survival from Heart Failure: A Prospective Study in Frail Patients in a Geriatric Unit.

Heart failure (HF) is one of the most frequent cause of hospitalization in elderly and often coexists with concurrent geriatric syndromes, like cognitive disturbances; various pathophysiological mechanisms are shared by HF and cognitive decline, notably a substrate of low-grade inflammation. We investigated whether SNPs in the purinergic receptor (P2X7R) and apolipoprotein (APO) E genes, both involved in a series of inflammatory responses, are associated to HF or cognitive impairment and are able to predict post-discharge mortality in the elderly. We prospectively analyzed 198 patients (age 85 ± 8 years, predominantly females) admitted to a Geriatric unit for acute HF, whose diagnosis was based on clinical signs, brain natriuretic peptide (BNP) values and ecocardiography in uncertain diagnosis (BNP values between 100 and 400 pg/mL); cognitive performance was assesed by Short Portable Mental Status Questionnaire (SPMSQ). In all the participants, SNPs rs208294 and rs3751143 for P2X7R gene and rs429558 and rs7412 for APOE gene were assessed. Information on all-cause mortality was adjudicated by medical records review 36 months after discharge. We found no relationship between P2X7R and APOE polymorphisms and 36-month post-discharge mortality; a better outcome for overall survival was observed in patients with BNP values below the median (281 pg/mL) (p=0.002) persisting after adjustment for renal function and age, and in those with cognitive impairment (p<0.001). Patients harboring APOE-ε4 genotype showed higher BNP concentrations than noncarriers (1289.9 ± 226.9 vs 580.5 ± 90.2 pg/mL respectively,p=0.004), whereas none of the studied SNPs were associated to impairment in cognitive performance. In conclusion, neither P2X7R or APOE genotype seem to predict long-term mortality in elderly patients. Interestingly, APOE-ε4 genotype was associated to higher BNP values, suggesting a putative interaction between genetic and biochemical markers in identifying people at risk for HF.

P2X7R Gene Polymorphisms are Associated with Increased Risk of Pulmonary Tuberculosis in the Tibetan Chinese Population.

In this study, we aim to explore the correlation between single nucleotide polymorphisms (SNPs) in the P2X7R gene and pulmonary tuberculosis (PTB) susceptibility in the Tibetan Chinese population in China. We examined 467 patients with active PTB and 504 healthy controls living in Xi'an and the surrounding area. Eight P2X7R SNPs were genotyped, and association analysis was performed. Odds ratios (ORs) and 95% confidence intervals (CIs) were tested by unconditional logistic regression analysis to evaluate the effects of the polymorphisms on PTB risk. P2X7R SNP association analyses were performed using SPSS 17.0 statistical packages and Microsoft Excel, SNP statistics software, Haploview software package (version 4.2), and SHEsis software platform. The results show that the "C" allele of rs656612 in the P2X7R gene was associated with an increased PTB risk by the additive model (OR = 1.307, 95% CI = 1.088-1.570, P = 0.004) and dominant model (rs656612, OR = 1.490, 95% CI = 1.153-1.926, P = 0.002). The "A" allele of rs208290 showed an increased PTB risk by the additive model (OR = 1.418, 95% CI = 1.179-1.706, P < 0.001) and dominant model (OR = 1.680, 95% CI = 1.297-2.177, P < 0.001), whereas the "A" allele of rs7958311 showed an increased risk by the additive model (rs7958311, OR = 1.260, 95% CI = 1.055-1.505, P = 0.011) and recessive model (OR = 1.609, 95% CI = 1.200-2.158, P = 0.001). After Bonferroni correction, rs208290 was found to be associated with PTB in the allele, dominant, and genotype models. In conclusion, our study revealed a significant association between three P2X7R gene polymorphisms (rs656612, rs208290, and rs7958311) and PTB in a Tibetan Chinese population.

Methamphetamine alters microglial immune function through P2X7R signaling.

BackgroundPurinoceptors have emerged as mediators of chronic inflammation and neurodegenerative processes. The ionotropic purinoceptor P2X7 (P2X7R) is known to modulate proinflammatory signaling and integrate neuronal-glial circuits. Evidence of P2X7R involvement in neurodegeneration, chronic pain, and chronic inflammation suggests that purinergic signaling plays a major role in microglial activation during neuroinflammation. In this study, we investigated the effects of methamphetamine (METH) on microglial P2X7R.MethodsESdMs were used to evaluate changes in METH-induced P2X7R gene expression via Taqman PCR and protein expression via western blot analysis. Migration and phagocytosis assays were used to evaluate functional changes in ESdMs in response to METH treatment. METH-induced proinflammatory cytokine production following siRNA silencing of P2X7R in ESdMs measured P2X7R-dependent functional changes. In vivo expression of P2X7R and tyrosine hydroxylase (TH) was visualized in an escalating METH dose mouse model via immunohistochemical analysis.ResultsStimulation of ESdMs with METH for 48 h significantly increased P2X7R mRNA (*p < 0.0336) and protein expression (*p < 0.022). Further analysis of P2X7R protein in cellular fractionations revealed increases in membrane P2X7R (*p < 0.05) but decreased cytoplasmic expression after 48 h METH treatment, suggesting protein mobilization from the cytoplasm to the membrane which occurs upon microglial stimulation with METH. Forty-eight hour METH treatment increased microglial migration towards Fractalkine (CX3CL1) compared to control (****p < 0.0001). Migration toward CX3CL1 was confirmed to be P2X7R-dependent through the use of A 438079, a P2X7R-competitive antagonist, which reversed the METH effects (****p < 0.0001). Similarly, 48 h METH treatment increased microglial phagocytosis compared to control (****p < 0.0001), and pretreatment of P2X7R antagonist reduced METH-induced phagocytosis (****p < 0.0001). Silencing the microglial P2X7R decreased TNF-α (*p < 0.0363) and IL-10 production after 48 h of METH treatment. Additionally, our studies demonstrate increased P2X7R and decreased TH expression in the striata of escalating dose METH animal model compared to controls.ConclusionsThis study sheds new light on the functional role of P2X7R in the regulation of microglial effector functions during substance abuse. Our findings suggest that P2X7R plays an important role in METH-induced microglial activation responses. P2X7R antagonists may thus constitute a novel target of therapeutic utility in neuroinflammatory conditions by regulating pathologically activated glial cells in stimulant abuse.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-016-0553-3) contains supplementary material, which is available to authorized users.

Genetic Association for P2X7R rs3751142 and CARD8 rs2043211 Polymorphisms for Susceptibility of Gout in Korean Men: Multi-Center Study.

The aim of this study was to determine the association between P2X7R rs3751142 and CARD8 rs2043211 polymorphisms and gout susceptibility in male Korean subjects. This study enrolled a total of 242 male patients with gout and 280 healthy controls. The polymorphisms of two individual genes including rs3751142(C>A) in the P2X7R gene and rs2043211(A>T) in the CARD8 gene were assessed using Taq-Man analysis. Statistical analyses were performed using the Chi-square test, Kruskal-Wallis test, and logistic regression analyses. A difference in genotypic frequency of the P2X7R rs3751142 and CARD8 rs2043211 genes was not detected between gout and control patients. Clinical parameters including age, onset age, disease duration, body mass index, and serum uric acid levels were not different among the three genotypes for either P2X7R or CARD8 (P > 0.05 for all). A pair-wise comparison of P2X7R rs3751142 and CARD8 rs2043211 genotype combinations revealed that subjects with the CA P2X7R rs3751142 genotype and the TT CARD8 rs2043211 genotype had a trend toward a higher risk of gout compared to the CC/AA combination (P = 0.056, OR = 2.618, 95% CI 0.975 - 7.031). In conclusion, this study revealed that genetic variability of the P2X7R rs3751142 and CARD8 rs2043211 genes might, in part, be associated with susceptibility for gout.

Correlation between P2X7 receptor gene polymorphisms and gout.

Not all patients with hyperuricemia will develop acute gouty arthritis, indicating that other initiating factors need to be considered. The P2X7 receptor is an adenosine triphosphate-gated nonselective cation channel that has also been suggested to be a proinflammatory receptor. In the immune system, the P2X7 receptor is involved in the processing and release of various proinflammatory cytokines, including interleukin-1β (IL-1β), IL-18 and tumor necrosis factor-α (TNF-α). IL-1β is a central cytokine in the initiation of the acute inflammatory response, which plays a key role in the pathogenesis of gout and the pathology of acute gouty arthritis. This review will explore single-nucleotide polymorphisms in the P2X7R gene [including rs1718119 (Ala348Thr), rs208294 (His155Tyr), rs3751143 (Glu496Ala), rs28360457 (Arg307Gln) and rs2230911 (Thr357Ser)] and their correlation with the incidence of gout. We conclude that P2X7R gene polymorphisms impact the secretion of IL-1β and thus play a vital role in the pathogenesis of gout.

Association of P2X7R Functional Expression and Gene Polymorphisms with Systemic Lupus Erythematosus

Association of P2X7R Functional Expression and Gene Polymorphisms with Systemic Lupus Erythematosus

Association of P2X7R Functional Expression and Gene Polymorphisms with Systemic Lupus Erythematosus

Objective: To investigate P2X purinoceptor 7 (P2X7R) expression changes on peripheral blood mononuclear cell (PBMC) surfaces of systemic lupus erythematosus (SLE) patients as well as their association with serum cytokine levels and patients’ clinical features. In addition, the effects of different P2X7R single nucleotide polymorphisms (SNPs) on P2X7R expression and cytokine production were investigated. Method: Twenty-nine new-onset SLE patients and twenty-eight healthy controls were enrolled, while P2X7R expression levels of lymphocytes, CD4+ cells and CD19+ cells were analyzed by flow cytometry. Serum IL-1β, IL-6 and TNF-α levels were analyzed by ELISA and three P2X7R SNPs (1068G>A, 1096C>G and 1513A>C) were PCR genotyped in 14 SLE patients and 14 healthy controls. Results: P2X7R surface expression levels of lymphocytes, CD4+ and CD19+ cells from new-onset SLE patients were significantly higher than that of controls and significantly elevated on lymphocytes from patients with concurrent arthritis or leukopenia as well as on CD19+ cells of NP-SLE patients. Moreover, P2X7R expression levels on lymphocytes and CD19+ cells of SLE patients were positively correlated with serum TNF-α/IL-6 and TNF-α level, respectively. SLE patients with the P2X7R 1068GG genotype had significantly higher expression level ratios of TNF-α, IL-6 and IL-1β to P2X7R on lymphocytes compared to patients harboring the 1068GA genotype. Conclusion: P2X7R, as an important cell surface regulator of several key cytokines, is involved in the pathogenesis of SLE and also associated with organ injuries like arthritis, leukopenia and neuropsychiatric damage. P2X7R 1068GG maybe a SLE susceptibility genotype since it enhances cytokine secretion in SLE patients.

Association of P2X7R gene polymorphisms with systemic lupus erythematosus in a Chinese population

The P2X7 receptor is a ligand-gated cationic channel receptor that is actived by ATP and normally expressed by a variety of immune system cells, including macrophages and lymphocytes. Because it leads to release of IL-1β and cell death by apoptosis or necrosis, it is a potential therapeutic target for a variety of autoimmune inflammatory diseases, such as systemic lupus erythematosus (SLE). The P2X7R gene is highly polymorphic, and many single-nucleotide polymorphisms (SNPs) have been detected. A case-control study was performed to investigate the associations of SNPs in the P2X7R gene (rs1718119, rs2230911 and rs3751143) with susceptibility to SLE in 535 Chinese SLE patients and 532 controls. Results showed that rs1718119 was associated with SLE; in particular carriers of the A allele and AA/AG/(AG+AA) genotypes were at lower risk of the disease [A versus G, P < 0.001, odds ratio (OR) = 0.543, 95% CI: 0.424-0.697; AG versus GG, P = 0.018, OR = 0.659, 95% CI: 0.466-0.931; AA versus GG, P = 0.011, OR = 0.176, 95% CI: 0.046-0.668; AG+AA versus GG, P = 0.004, OR = 0.607, 95% CI: 0.433-0.850], but no significant differences in rs2230911 and rs3751143 were observed between SLE patients and controls. Stratification of cases for the presence of nephritis showed that rs2230911 G allele and CG/(CG+GG) genotypes were at a lower risk of SLE with nephritis (LN) (G versus C, P = 0.011, OR = 0.640, 95% CI: 0.454-0.903; CG versus CC, P = 0.035, OR = 0.645, 95% CI: 0.429-0.970; GG versus CC, P = 0.101, OR = 0.349, 95% CI: 0.099-1.228; CG+GG versus CC, P = 0.015 OR = 0.612, 95% CI: 0.411-0.910), but rs1718119 and rs3751143 were not associated with LN. Analysis of the haplotypes revealed one haplotype (ACA) that appeared to be a significantly 'protective' haplotype (P = 0.009, OR = 0.708, 95% CI: 0.546-0.918) with SLE. The findings suggest that the P2X7R gene might contribute to SLE susceptibility in the Chinese population.

Adipocyte P2X7 receptors expression: A role in modulating inflammatory response in subjects with metabolic syndrome?

ObjectiveP2X7 receptor (P2X7R), upon its stimulation with extracellular ATP, modulates several inflammatory responses in different cell types. No information is available on its presence in human adipocytes and its potential involvement in the chronic inflammation associated with metabolic syndrome (MS). Therefore, we evaluated P2X7R presence and functional activity in adipocytes from visceral (VAT) and subcutaneous (SAT) adipose tissue of patients with MS and controls (CTL). MethodsAdipocyte gene expression of TNFα, IL-6 and PAI-1 (by realtime-PCR) and their plasma concentrations (ELISA); P2X7R expression (realtime-PCR, Western blot and immunofluorescence); P2X7R functional activity (intracellular calcium fluxes by fluorimetry); cytokine release from adipocytes (ELISA). The inflammasome components were also determined. ResultsIn VAT, TNFα, IL-6 and PAI-1 were more expressed in MS than in CTL. These differences were confirmed in SAT for IL-6 and PAI-1. Plasma IL-6, PAI-1 and TNFα levels were higher in MS. P2X7R mRNA and protein, identified in both VAT and SAT, were more abundant in MS than in CTL. Immunofluoresce confirmed the typical “ring-like” arrangement of P2X7R at the plasma membrane. Benzoyl-benzoyl-ATP raised intracellular calcium both in VAT and SAT, and induced IL-6, TNFα and PAI-1 release in both MS and CTL cells. This effect was partially inhibited by KN62, specific human P2X7R blocker, or by P2X7R gene silencing. The inflammasome was more activated in MS than in CTL adipocytes. ConclusionHuman adipocytes express functionally active P2X7R, which modulate the release of inflammatory cytokines, at least in part via inflammasome activation. Adipocytes from MS patients show an enhanced P2X7R expression, which might contribute to the subclinical inflammatory status characterizing these patients and conferring them an increased CV risk.

P2X7 receptor gene polymorphism analysis in rheumatoid arthritis

The P2X7 receptor, a member of the P2X family of nucleotide-gated channels, is predominantly expressed by monocytic cells. The activation of this receptor has been associated with downstream-signalling cascades, resulting in the release of a number of inflammatory mediators. There are more than 815 single nucleotide polymorphisms (SNPs) that have been described in the human P2X7R gene, but only few have been functionally characterized. The main aim of this study is to determine whether P2X7R gene polymorphisms confer susceptibility to rheumatoid arthritis (RA). A total of 125 patients with RA and 158 healthy volunteers were enrolled in this study. DNA fragment was PCR amplified and sequenced on the AB 3130 Genetic Analyzer. No significant difference in allele frequencies of 489 C→T, 1096 C→G and 1513 A→C polymorphisms, among sporadic cases of RA and healthy controls was found. However, the 1513A/C genotype was significantly associated with the presence of rheumatoid factor and anti-MCV autoantibody in RA patients. Interestingly, the genotype frequency of 1068 A/A was 0.19 in the RA group and 0.09 in control group (P = 0.025). Consequently, this polymorphism (AA) is two folds greater in the RA group compared to controls. Moreover, this polymorphism was significantly associated with mean concentration of C-reactive protein in RA patients. In contrast, 946G→A and 1729 T→A were not detected in both groups. As a result, these two polymorphisms are uncommon in Omani Arab population. Polymorphism at position 1068 and 1513 in the P2X7R gene might contribute to the pathogenesis of RA. Moreover, the loss-of-function SNP at position 1096 C→G or the gain-of-function SNP at position 489 C→T of the P2X7 gene does not appear to be a susceptibility gene locus for the development of RA. Further studies are required to confirm this finding.