Circulating P2X7 Receptor Signaling Components as Diagnostic Biomarkers for Temporal Lobe Epilepsy.

Circulating molecules have potential as biomarkers to support the diagnosis of epilepsy and to assist with differential diagnosis, for example, in conditions resembling epilepsy, such as in psychogenic non-epileptic seizures (PNES). The P2X7 receptor (P2X7R) is an important regulator of inflammation and mounting evidence supports its activation in the brain during epilepsy. Whether the P2X7R or P2X7R-dependent signaling molecules can be used as biomarkers of epilepsy has not been reported. P2X7R levels were analyzed by quantitative ELISA using plasma samples from controls and patients with temporal lobe epilepsy (TLE) or PNES. Moreover, blood cell P2X7R expression and P2X7R-dependent cytokine signature was measured following status epilepticus in P2X7R-EGFP reporter, wildtype, and P2X7R-knockout mice. P2X7R plasma levels were higher in TLE patients when compared with controls and patients with PNES. Plasma levels of the broad inflammatory marker protein C-Reactive protein (CRP) were similar between the three groups. Using P2X7R-EGFP reporter mice, we identified monocytes as the main blood cell type expressing P2X7R after experimentally evoked seizures. Finally, cytokine array analysis in P2X7R-deficient mice identified KC/GRO as a potential P2X7R-dependent plasma biomarker following status epilepticus and during epilepsy. Our data suggest that P2X7R signaling components may be a promising subclass of circulating biomarkers to support the diagnosis of epilepsy.

Minimally invasive quantification of cerebral P2X7R occupancy using dynamic [18F]JNJ-64413739 PET and MRA-driven image derived input function.

[18F]JNJ-64413739 has been evaluated as PET-ligand for in vivo quantification of purinergic receptor subtype 7 receptor (P2X7R) using Logan graphical analysis with a metabolite-corrected arterial plasma input function. In the context of a P2X7R PET dose occupancy study, we evaluated a minimally invasive approach by limiting arterial sampling to baseline conditions. Meanwhile, post dose distribution volumes (VT) under blocking conditions were estimated by combining baseline blood to plasma ratios and metabolite fractions with an MR angiography driven image derived input function (IDIF). Regional postdose VT,IDIF values were compared with corresponding VT,AIF estimates using a arterial input function (AIF), in terms of absolute values, test-retest reliability and receptor occupancy. Compared to an invasive AIF approach, postdose VT,IDIF values and corresponding receptor occupancies showed only limited bias (Bland-Altman analysis: 0.06 ± 0.27 and 3.1% ± 6.4%) while demonstrating a high correlation (Spearman ρ = 0.78 and ρ = 0.98 respectively). In terms of test-retest reliability, regional intraclass correlation coefficients were 0.98 ± 0.02 for VT,IDIF compared to 0.97 ± 0.01 for VT,AIF. These results confirmed that a postdose IDIF, guided by MR angiography and using baseline blood and metabolite data, can be considered for accurate [18F]JNJ-64413739 PET quantification in a repeated PET study design, thus avoiding multiple invasive arterial sampling and increasing dosing flexibility.

Correlations between Serum P2X7, Vitamin A, 25-hydroxy Vitamin D, and Mycoplasma Pneumoniae Pneumonia.

BACKGROUND: Identifying new molecular diagnostic markers for Mycoplasma Pneumoniae Pneumonia (MPP) has always been an essential topic since MPP cases have increased every year, especially among children. Here, we examined the correlation between serum level of Purinergic receptor P2X7, vitamin A, and 25-hydroxy vitamin D (25(OH)D) and the severity of MPP, aiming to identify molecules that have the potential to become diagnostic markers. METHODS: This study was conducted on 186 cases aged 1-14 (136 MPP and 50 non-MPP patients). Serum levels of Purinergic receptor P2X7, vitamin A, 25(OH)D, and multiple inflammatory and immune factors were measured, compared, and tested for statistical significance. RESULTS: Serum P2X7, tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) levels were significantly increased in severe MPP patients, while serum vitamin A, 25(OH)D, IgA, and IgG levels were significantly decreased. CONCLUSION: Our results demonstrated a positive correlation between serum P2X7 level and the severity of MPP, and negative correlations between serum levels of vitamin A and 25(OH)D and the severity of MPP, suggesting that high serum levels of P2X7 and low serum levels of vitamin A and 25(OH)D may indicate relatively severer MPP.

Elevated circulating level of P2X7 receptor is related to severity of coronary artery stenosis and prognosis of acute myocardial infarction.

BACKGROUND: Acute myocardial infarction (AMI) is a severely life-threatening cardiovascular disease. Previous research has identified an association between the P2X7 receptor (P2X7R) and the development of atherosclerosis. However, the correlation of its expression with the clinical prognosis of patients with AMI remains unclear. The present study aimed to investigate the potential role of P2X7R in Chinese patients with AMI. METHODS: Seventy-nine patients with AMI and 48 controls were consecutively enrolled in this prospective observational study. Circulating P2X7R mRNA expression levels and other clinical variables were determined upon admission to the hospital. Patients were followed up for 360 days, and the end-point was considered as the occurrence of major adverse cardiovascular events (MACE). RESULTS: Circulating P2X7R mRNA expression level in peripheral blood mononuclear cells of patients with AMI were significantly higher than those in controls and had promising diagnostic ability of AMI with an area under the curve of 0.928. Furthermore, P2X7R was demonstrated to be correlated positively with the severity of coronary artery stenosis. Additionally, this is the first study to indicate that higher P2X7R mRNA expression is associated with a higher rate of MACE within 360 days after AMI. CONCLUSIONS: The present study showed that the circulating level of P2X7R was elevated in AMI patients and was closely associated with the severity of coronary artery stenosis and prognosis of AMI.

The P2X7 Receptor Is Shed Into Circulation: Correlation With C-Reactive Protein Levels.

The P2X7 receptor (P2X7R) is a key pro-inflammatory plasma membrane receptor responsible for NLRP3 inflammasome activation and IL-1ß release. Various inflammatory plasma membrane receptors (e.g., IL-1 type I receptor, TNF type I and II receptors, IL-2 receptor) are shed under different pathophysiological conditions. In the present study, we show that the full length P2X7R is released into circulation in patients as well as in healthy subjects. Blood levels of shed P2X7R (sP2X7R) correlate to those of the inflammatory marker C reactive protein (CRP). Blood sP2X7R ranged from 16.74 to 82.17 ng/L, mean ± SE 40.97 ± 3.82 (n = 26) in healthy subjects, from 33.1 to 484.0 ng/L, mean ± SE 114.78 ± 12.22 (n = 45) in patients with CRP <3 mg/L, and from 63.65 to 1092.3 ng/L, mean ± SE 204.2 ± 30.94 (n = 42) in patients with CRP >3 mg/L. sP2X7R in plasma was largely associated to microvesicles/microparticles. Peripheral blood monocytes from healthy subjects released sP2X7R upon stimulation with the semi-selective P2X7R agonist benzoyl ATP. These data show that the P2X7R can be released into circulation, and that its blood levels increase in various disease conditions.

The role of vitamin D and P2X7R in multiple sclerosis.

Multiple sclerosis (MS) is characterized by neuroinflammatory infiltrates and central nervous system demyelination. In the neuroinflammatory foci of MS there is increased expression of a purinergic receptor, P2X7R. Although implicated in the neuroinflammation, the exact role of P2X7R in the context of MS is unclear and forms the basis of this review. In this review, we also introduce the immunopathologies and inflammatory processes in MS, with a focus on P2X7R and the possible immunomodulatory role of vitamin D deficiency in this setting.

Bipolar disorder and 1513A>C P2RX7 polymorphism frequency.

Although the etiology of Bipolar Disorder (BD) remains unknown, a strong genetic component to the pathogenesis and risk for this disorder has been widely hypothesized. Several risk genes for BD have been identified; of these, the purinergic P2 × 7 receptor (P2 × 7R) constitutes a pro-inflammatory receptor and a potential risk gene candidate. The purpose of the present study was to assess the frequency of the 1513 A > C P2RX7 polymorphism (rs3751143; Glu496Ala), which leads to receptor loss-of-function, in 154 BD patients versus 184 control subjects. The existence of a differential modulation of P2 × 7R was also analyzed in 22 euthymic BD patients, in comparison to 18 healthy controls. Our data show a decrease in 1513C allele frequency (p = 0.045) and a potential increase in 1513 A A/AC (p = 0.055) genotype frequency in BD patients, compared to controls, indicating an enhanced function of the pro-inflammatory P2 × 7 receptor in BD subjects. Interestingly, no differences in P2RX7 gene and protein expression were found between euthymic BD patients and matched healthy controls. In conclusion, our results suggest that P2 × 7R might play a role in the pathophysiology of BD and add new information regarding this receptor as a potential biomarker for the prediction and diagnosis of the disorder.

The presence of the 1068 G>A variant of P2X7 receptors is associated to an increase in IL-1Ra levels, insulin secretion and pancreatic ß-cell function but not with glycemic control in type 2 diabetes patients.

It has been reported that an increased function of the P2X7 purinergic receptor is associated with an increase in both insulin sensitivity and secretion. Accordingly, we explored the possible effect of the 1068 G>A polymorphism of the gene P2RX7 on glucose homeostasis and the levels of the anti-inflammatory cytokine IL-1Ra in T2D patients. The presence of the 1068 G>A polymorphism in T2D patients (n = 100) and healthy subjects (n = 100) was determined by DNA sequencing, and serum levels of IL-1Ra were measured by ELISA. Pancreatic ß-cell function, insulin resistance, blood glucose levels and glycated hemoglobin (HbA1c) were also analyzed. We detected a significant negative association between T2D and the 1068 G>A SNP (Odds ratio 0.3916, p = 0.0045). In addition, we observed that T2D patients bearing the 1068 G>A variant showed higher serum levels of IL-1Ra compared to both, patients with the GG genotype or healthy individuals (GG or G>A). Moreover, T2D patients bearing the 1068 G>A SNP showed increased insulin levels and a better pancreatic ß-cell function (p < 0.05 in both cases) compared to patients with the wild type genotype. However, the HbA1c levels, fasting glucose levels and the degree of insulin resistance were similar in T2D patients carrying or not the G>A SNP. Our results suggest that although the 1068 G>A polymorphism of the P2RX7 gene is associated with an increased ß-cell function and IL-1Ra release in T2D patients, the glycemic control is not significantly affected by the presence of this SNP.

Differential expression of P2X7 receptor and IL-1ß in nociceptive and neuropathic pain.

BACKGROUND: Despite substantial progress, pathogenesis and therapy of chronic pain are still the focus of many investigations. The ATP-gated P2X7 receptor (P2X7R) has previously been shown to play a central role in animal models of nociceptive inflammatory and neuropathic pain. Recently, we found that the adaptive immune system is involved in the pathophysiology of chronic nociceptive and neuropathic pain in humans. So far, data regarding P2X7R expression patterns on cells of the adaptive immune system of pain patients are scarce. We therefore analyzed the P2X7R expression on peripheral blood lymphocytes and monocytes, as well as serum levels of IL-1ß in patients suffering from chronic nociceptive and neuropathic pain in comparison to healthy volunteers in order to identify individuals who might benefit from a P2X7R modulating therapy. METHODS: P2X7R messenger RNA (mRNA) and protein expression were determined in patients with either chronic nociceptive low back pain (CLBP) or neuropathic pain (NeP), and in healthy volunteers by quantitative real-time PCR (qPCR) and by fluorescence-assisted cell-sorting (FACS), respectively. IL-1ß serum levels were measured with a multiplex cytokine assay. RESULTS: Compared to healthy volunteers, P2X7R mRNA (1.6-fold, p = 0.038) and protein levels were significantly increased on monocytes (NeP: 24.6 ± 6.2, healthy volunteers: 17.0 ± 5.4; p = 0.002) and lymphocytes (NeP: 21.8 ± 6.5, healthy volunteers: 15.6 ± 5.2; p = 0.009) of patients with NeP, but not in patients with CLBP. Similarly, IL-1ß serum concentrations were significantly elevated only in NeP patients (1.4-fold, p = 0.04). CONCLUSIONS: A significant upregulation of P2X7R and increased IL-1ß release seems to be a particular phenomenon in patients with NeP. P2X7R inhibitors may therefore represent a potential option for the treatment of this frequently intractable type of pain. German Clinical Trial Register (DRKS): Registration Trial DRKS00005954.

P2X7 Receptor Expression in Peripheral Blood Monocytes Is Correlated With Plasma C-Reactive Protein and Cytokine Levels in Patients With Type 2 Diabetes Mellitus: a Preliminary Report.

Chronic inflammation plays a major role in development of type 2 diabetes mellitus (T2DM). C-reactive protein (CRP) and inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin 1ß (IL-1ß) are directly involved in the occurrence of insulin resistance. Increased extracellular ATP levels can amplify the inflammatory response in vivo via the P2X7 receptor. The present study aimed to assess the relationship between P2X7 receptor expression in human peripheral blood monocytes and plasma levels of TNF-α, IL-1ß, and CRP in T2DM patients. The results showed the association of increased P2X7 receptor expression of monocytes with high serum CRP, TNF-α, and IL-1ß levels. TNF-α and IL-1ß levels were lowest in healthy subjects; in T2DM patients, these inflammatory markers were less abundant in individuals with normal CRP levels compared to those with high CRP contents. In contrast, IL-10 levels in T2DM patients with high CRP levels were dramatically decreased. P2X7 receptor expression in monocytes from T2DM patients with high CRP levels was significantly increased in comparison with healthy individuals and T2DM patients with normal CRP levels. These findings indicated that P2X7 receptor in peripheral blood monocytes may be involved in the pathological changes of T2DM, particularly affecting patients with high CRP levels.

Decrease of serum adenine nucleotide hydrolysis in an irritant contact dermatitis mice model: potential P2X7R involvement.

Extracellular adenosine 5'-triphosphate (ATP) has significant effects on a variety of pathological conditions and it is the main physiological agonist of P2X7 purinergic receptor (P2X7R). It is known that ATP acting via purinergic receptors plays a relevant role on skin inflammation, and P2X7R is required to neutrophil recruitment in a mice model of irritant contact dermatitis (ICD).The present study investigated the effects of chemical irritant croton oil (CrO) upon ATP, ADP, and AMP hydrolysis in mice blood serum, and the potential involvement of P2X7R. The topical application CrO induced a decrease on soluble ATP/ADPase activities (~50 %), and the treatment with the selective P2X7R antagonist, A438079, reversed these effects to control level. Furthermore, we showed that CrO decreased cellular viability (52.6 % ± 3.9) in relation to the control and caused necrosis in keratinocytes (PI positive cells). The necrosis induced by CrO was prevented by the pre-treatment with the selective P2X7R antagonist A438079. The results presented herein suggest that CrO exerts an inhibitory effect on the activity of ATPDase in mouse serum, reinforcing the idea that ICD has a pathogenic mechanism dependent of CD39. Furthermore, it is tempting to suggest that P2X7R may act as a controller of the extracellular levels of ATP.