Amyloid β Peptide Induces Apoptosis Through P2X7 Cell Death Receptor in Retinal Cells: Modulation by Marine Omega-3 Fatty Acid DHA and EPA

Role of P2X7R in Retinal Diseases: A Review

BACKGROUND

P2X purinoceptor 7 receptor (P2X7R) is an ATP-gated ion channel that, upon activation by ATP, triggers the release of inflammatory mediators and induces apoptosis in cells. This channel plays a crucial role in the onset and progression of various diseases. Recently, there has been a growing body of research focused on the function of P2X7R receptors in ophthalmic conditions, particularly concerning retinal diseases such as age-related macular degeneration, diabetic retinopathy, and retinitis pigmentosa.

OBJECTIVE

This article is to provide a comprehensive review of the advancements in the study of P2X7R and its association with retinal diseases, elucidating its role in these conditions and identifying potential avenues for future research.

METHODS

Electronic databases, including PubMed, Web of Science, and Wan fang Data were searched for relevant literature. The following keywords were used: "P2X7R", Age-related macular degeneration", "Diabetic retinopathy", "Retinitis pigmentosa". Both preclinical and clinical studies were included to provide a holistic understanding of P2X7R's role in retinal pathology.

RESULTS

P2X7R activation exacerbates retinal diseases by promoting inflammation and apoptosis. However, its role in disease progression and homeostasis complicates therapeutic targeting, highlighting the need for selective inhibitors and further research into its context-dependent functions.

CONCLUSION

P2X7R plays a critical role in the pathogenesis of retinal diseases. At the same time, preclinical studies suggest that P2X7R inhibition holds promise as a therapeutic strategy. Future research should focus on developing selective P2X7R inhibitors, elucidating the receptor's role in different disease stages, and identifying biomarkers to guide personalized treatment. Addressing these challenges will be essential for translating P2X7R-targeted therapies into clinical practice and improving outcomes for patients with retinal diseases.

Antioxidants in Age-Related Macular Degeneration: Lights and Shadows

Age-related macular degeneration (AMD) is a leading cause of vision impairment worldwide, primarily driven by oxidative stress and inflammation. This review examines the role of antioxidants in mitigating oxidative damage, emphasizing both their therapeutic potential and limitations in AMD management. Key findings underscore the efficacy of specific antioxidants, including vitamins C and E, lutein, zeaxanthin, and Coenzyme Q10, in slowing AMD progression. Landmark studies such as AREDS and AREDS2 have shaped current antioxidant formulations, although challenges persist, including patient variability and long-term safety concerns. Emerging therapies, such as mitochondrial-targeted antioxidants and novel compounds like saffron and resveratrol, offer promising avenues for AMD treatment. Complementary lifestyle interventions, including antioxidant-rich diets and physical activity, further support holistic management approaches. This review highlights the critical role of antioxidants in AMD therapy, advocating for personalized strategies to optimize patient outcomes.

Understanding the Impact of Polyunsaturated Fatty Acids on Age-Related Macular Degeneration: A Review

Age-related Macular Degeneration (AMD) is a multifactorial ocular pathology that destroys the photoreceptors of the macula. Two forms are distinguished, dry and wet AMD, with different pathophysiological mechanisms. Although treatments were shown to be effective in wet AMD, they remain a heavy burden for patients and caregivers, resulting in a lack of patient compliance. For dry AMD, no real effective treatment is available in Europe. It is, therefore, essential to look for new approaches. Recently, the use of long-chain and very long-chain polyunsaturated fatty acids was identified as an interesting new therapeutic alternative. Indeed, the levels of these fatty acids, core components of photoreceptors, are significantly decreased in AMD patients. To better understand this pathology and to evaluate the efficacy of various molecules, in vitro and in vivo models reproducing the mechanisms of both types of AMD were developed. This article reviews the anatomy and the physiological aging of the retina and summarizes the clinical aspects, pathophysiological mechanisms of AMD and potential treatment strategies. In vitro and in vivo models of AMD are also presented. Finally, this manuscript focuses on the application of omega-3 fatty acids for the prevention and treatment of both types of AMD.

The contribution of pattern recognition receptor signalling in the development of age related macular degeneration: the role of toll-like-receptors and the NLRP3-inflammasome

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss, characterised by the dysfunction and death of the photoreceptors and retinal pigment epithelium (RPE). Innate immune cell activation and accompanying para-inflammation have been suggested to contribute to the pathogenesis of AMD, although the exact mechanism(s) and signalling pathways remain elusive. Pattern recognition receptors (PRRs) are essential activators of the innate immune system and drivers of para-inflammation. Of these PRRs, the two most prominent are (1) Toll-like receptors (TLR) and (2) NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3)-inflammasome have been found to modulate the progression of AMD. Mutations in TLR2 have been found to be associated with an increased risk of developing AMD. In animal models of AMD, inhibition of TLR and NLRP3 has been shown to reduce RPE cell death, inflammation and angiogenesis signalling, offering potential novel treatments for advanced AMD. Here, we examine the evidence for PRRs, TLRs2/3/4, and NLRP3-inflammasome pathways in macular degeneration pathogenesis.

Role of Oxysterols in Ocular Degeneration Mechanisms and Involvement of P2X7 Receptor

Ocular degeneration, including cataracts, glaucoma, macular degeneration, and diabetic retinopathy, is a major public health challenge, as it affects the quality of life of millions of people worldwide and, in its advanced stages, leads to blindness. Ocular degeneration, although it can affect different parts of the eye, shares common characteristics such as oxysterols and the P2X7 receptor. Indeed, oxysterols, which are cholesterol derivatives, are associated with ocular degeneration pathogenesis and trigger inflammation and cell death pathways. Activation of the P2X7 receptor is also linked to ocular degeneration and triggers the same pathways. In age-related macular degeneration, these two key players have been associated, but further studies are needed to extrapolate this interrelationship to other ocular degenerations.

Purinergic signaling via P2X receptors and mechanisms of unregulated ATP release in the outer retina and age-related macular degeneration

Age-related macular degeneration (AMD) is a chronic and progressive inflammatory disease of the retina characterized by photoceptor loss and significant central visual impairment due to either choroidal neovascularization or geographic atrophy. The pathophysiology of AMD is complex and multifactorial, driven by a combination of modifiable and non-modifiable risk factors, molecular mechanisms, and cellular processes that contribute to overall disease onset, severity, and progression. Unfortunately, due to the structural, cellular, and pathophysiologic complexity, therapeutic discovery is challenging. While purinergic signaling has been investigated for its role in the development and treatment of ocular pathologies including AMD, the potential crosstalk between known contributors to AMD, such as the complement cascade and inflammasome activation, and other biological systems, such as purinergic signaling, have not been fully characterized. In this review, we explore the interactions between purinergic signaling, ATP release, and known contributors to AMD pathogenesis including complement dysregulation and inflammasome activation. We begin by identifying what is known about purinergic receptors in cell populations of the outer retina and potential sources of extracellular ATP required to trigger purinergic receptor activation. Next, we examine evidence in the literature that the purinergic system accelerates AMD pathogenesis leading to apoptotic and pyroptotic cell death in retinal cells. To fully understand the potential role that purinergic signaling plays in AMD, more research is needed surrounding the expression, distribution, functions, and interactions of purinergic receptors within cells of the outer retina as well as potential crosstalk with other systems. By determining how these processes are affected in the context of purinergic signaling, it will improve our understanding of the mechanisms that drive AMD pathogenesis which is critical in developing treatment strategies that prevent or slow progression of the disease.

JEG-3 placental cells in toxicology studies: a promising tool to reveal pregnancy disorders

Placental alterations are responsible for adverse pregnancy outcomes like preeclampsia and intrauterine growth restriction. And yet, placenta toxicology has not become a fully-fledged toxicology field. Because placenta is very often seen only as a barrier between the mother and the fetus, there is a lack and therefore a need for an experimental human model with technical recommendations to study placenta toxicology. In vitro approaches are recommended in experimental toxicology as they focus on a specific biological process and yield high-throughput screening methods. In the present study, we first established incubation conditions to preserve signatures of the human JEG-3 cell line identity while enabling toxicity detection. JEG-3 cells prepared in our incubation conditions were renamed JEG-Tox cells. As placental alterations are mainly triggered by uncontrolled apoptosis, we second used known apoptotic agents pregnant women are exposed to, to check that JEG-Tox cells can trigger apoptosis. Ethanol, bisphenol F, quinalphos, 4,4'-DDT, benzalkonium chloride, phenoxyethanol, propylparaben, and perfluorooctanic acid all induced chromatin condensation in JEG-Tox cells. Our incubation conditions allow JEG-Tox cells to keep placental cell identity and to respond to toxic chemicals. JEG-Tox cells are a pertinent model for placenta toxicology and could be used to better understand pregnancy alterations.

Identification of rs11615992 as a novel regulatory SNP for human P2RX7 by allele-specific expression

P2RX7 (purinergic receptor P2X 7) is an important membrane ion channel and involved in multiple physiological processes. One non-synonymous SNP on P2RX7, rs3751143, had been proven to reduce ion channel function and further associated with multiple diseases. However, it was still unclear whether there were other cis-regulatory elements for P2RX7, which might further contribute to related diseases. Allele-specific expression (ASE) is a robust and sensitive approach to identify the potential functional region in human genome. In the current study, we measured ASE on rs3751143 in lung tissues and observed a consistent excess of A allele over C (P = 0.001), which indicated that SNP(s) in linkage disequilibrium (LD) could regulate P2RX7 expression. By analyzing the 1000 genomes project data for Chinese, one SNP locating ~ 5 kb away and downstream of P2RX7, rs11615992, was disclosed to be in strong LD with rs3751143. The dual-luciferase assay confirmed that rs11615992 could alter target gene expression in lung cell line. Through chromosome conformation capture, it was verified that the region surrounding rs11615992 could interact with P2RX7 promoter and effect as an enhancer. By chromatin immunoprecipitation, the related transcription factor POU2F1 (POU class 2 homeobox 1) was recognized to bind the region spanning rs11615992. Our work identified a novel long-distance cis-regulatory SNP for P2RX7, which might contribute to multiple diseases.

Visual Features in Alzheimer's Disease: From Basic Mechanisms to Clinical Overview

Alzheimer's disease (AD) is the leading cause of dementia worldwide. It compromises patients' daily activities owing to progressive cognitive deterioration, which has elevated direct and indirect costs. Although AD has several risk factors, aging is considered the most important. Unfortunately, clinical diagnosis is usually performed at an advanced disease stage when dementia is established, making implementation of successful therapeutic interventions difficult. Current biomarkers tend to be expensive, insufficient, or invasive, raising the need for novel, improved tools aimed at early disease detection. AD is characterized by brain atrophy due to neuronal and synaptic loss, extracellular amyloid plaques composed of amyloid-beta peptide (Aβ), and neurofibrillary tangles of hyperphosphorylated tau protein. The visual system and central nervous system share many functional components. Thus, it is plausible that damage induced by Aβ, tau, and neuroinflammation may be observed in visual components such as the retina, even at an early disease stage. This underscores the importance of implementing ophthalmological examinations, less invasive and expensive than other biomarkers, as useful measures to assess disease progression and severity in individuals with or at risk of AD. Here, we review functional and morphological changes of the retina and visual pathway in AD from pathophysiological and clinical perspectives.

P2X7 as a scavenger receptor for innate phagocytosis in the brain

The P2X7 receptor has been widely studied for its ATP-induced pro-inflammatory effect, but in the absence of a ligand, P2X7 has a second function as a scavenger receptor, which is active in the development of the human brain. The scavenger activity of P2X7 is only evident in the absence of serum but is fully active in cerebrospinal fluid. P2X7 on the cell surface is present as a membrane complex, and an attachment to non-muscle myosin of the cytoskeleton is required for particle engulfment. Selective antagonists of P2X7 pro-inflammatory function have little effect on phagocytosis, but inheritance of a variant haplotype spanning the P2RX7 and P2RX4 genes has been associated with loss of P2X7-mediated phagocytosis. Recent studies in mice suggest that the innate phagocytosis mediated by P2X7 receptors declines with ageing. Thus, defective P2X7-mediated phagocytosis may contribute to age-related neuro-degenerative diseases including Alzheimer's disease, age-related macular degeneration and primary progressive multiple sclerosis.

Purinergic modulation of frog electroretinographic responses: The role of the ionotropic receptor P2X7

The contribution of the purinergic receptors P2X7 (P2X7Rs) to the electroretinographic (ERG) responses was studied by testing the effects of the selective P2X7R antagonist A438079 and the selective P2X7R agonist Bz-ATP on the electroretinograms obtained in perfused frog (Rana ridibunda) eyecup preparations under a variety of stimulation conditions. The P2X7R blockade by 200 µM A438079 diminished the amplitude of the photoreceptor components: the a-wave and the pharmacologically isolated mass receptor potential. In the pure rod-driven and pure cone-driven responses, the amplitude of the postreceptoral ON (b-wave) and OFF (d-wave) components was also diminished. The OFF responses were affected to a greater extent compared to the ON responses. In the mixed rod- and cone-driven responses, obtained in the mesopic intensity range, the b-wave amplitude was increased, while the d-wave amplitude was decreased. The amplitude of the oscillatory potentials was diminished. The relative amplitude changes produced by the P2X7R blockade were greater in the dark-adapted compared to the light-adapted eyes. The application of 100 µM Bz-ATP produced small effects opposite to those of the antagonist, while a prolonged (>20 min) treatment with 1 mM Bz-ATP resulted in a significant amplitude reduction or even abolishment of b- and d-waves. Our results show that endogenous ATP through its P2X7Rs exerts significant, mostly potentiating effects on the ERG photoreceptor and postreceptoral responses. There is a clear ON/OFF asymmetry of the effects on the ERG postreceptoral responses favoring OFF responses: they are always strongly potentiated, while the ON responses are either less potentiated (in the rod-driven and most of the cone-driven responses) or even inhibited (in the mixed rod- and cone-driven responses). The overstimulation of P2X7Rs can produce acute pathological changes, that is, a decrease or abolishment of the ERG responses.

Fatty Acids Dietary Supplements Exert Anti-Inflammatory Action and Limit Ganglion Cell Degeneration in the Retina of the EAE Mouse Model of Multiple Sclerosis

Optic neuritis is an acute inflammatory demyelinating disorder of the optic nerve (ON) and is an initial symptom of multiple sclerosis (MS). Optic neuritis is characterized by ON degeneration and retinal ganglion cell (RGC) loss that contributes to permanent visual disability and lacks a reliable treatment. Here, we used the experimental autoimmune encephalomyelitis (EAE) mouse model of MS, a well-established model also for optic neuritis. In this model, C57BL6 mice, intraperitoneally injected with a fragment of the myelin oligodendrocyte glycoprotein (MOG), were found to develop inflammation, Müller cell gliosis, and infiltration of macrophages with increased production of oncomodulin (OCM), a calcium binding protein that acts as an atypical trophic factor for neurons enabling RGC axon regeneration. Immunolabeling of retinal whole mounts with a Brn3a antibody demonstrated drastic RGC loss. Dietary supplementation with Neuro-FAG (nFAG^®), a balanced mixture of fatty acids (FAs), counteracted inflammatory and gliotic processes in the retina. In contrast, infiltration of macrophages and their production of OCM remained at elevated levels thus eventually preserving OCM trophic activity. In addition, the diet supplement with nFAG exerted a neuroprotective effect preventing MOG-induced RGC death. In conclusion, these data suggest that the balanced mixture of FAs may represent a useful form of diet supplementation to limit inflammatory events and death of RGCs associated to optic neuritis. This would occur without affecting macrophage infiltration and the release of OCM thus favoring the maintenance of OCM neuroprotective role.

Purinergic P2X7 receptor functional genetic polymorphisms are associated with the susceptibility to obesity in Chinese postmenopausal women

OBJECTIVE

We conducted a case-control study to investigate the associations of functional single-nucleotide polymorphisms in the purinergic P2X7 receptor (P2X7R) gene (rs2393799, rs7958311, rs1718119, rs2230911, and rs3751143) with obesity and overweight in a population of Chinese postmenopausal women.

METHODS

Our study included 180 obese women, 179 overweight women, and 204 controls. All participants were genotyped at the P2X7R rs2393799, rs7958311, rs1718119, rs2230911, and rs3751143 loci via allele-specific polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism procedures. The relationships between P2X7R genetic polymorphisms and their associated haplotypes with obesity (body mass index [BMI] ≥30 kg/m] and overweight (25 kg/m ≤ BMI < 30 kg/m) were evaluated.

RESULTS

Our results showed that P2X7R rs2230911G and rs1718119A were associated with an increased risk of obesity; in particular, both carriers of the rs2230911G allele and GG/(CG + GG) genotypes (G vs C, P < 0.001, odds ratio [OR] 2.87, 95% confidence interval [CI] 1.98-4.16; GG vs CC, P < 0.001, OR 8.76, 95% CI 3.29-23.35; CG + GG vs CC, P < 0.001, OR 2.54, 95% CI 1.63-3.95) and carriers of the rs17181191A allele and GA/(GA + AA) genotypes (A vs G, P < 0.001, OR 2.97, 95% CI 1.86-4.74; GA vs GG, P = 0.001, OR 2.72, 95% CI 1.55-4.79; GA + AA vs GG, P < 0.001, OR 3.05, 95% CI 1.79-5.19) were at a higher risk of obesity. No association with obesity or overweight was observed for the other three P2X7R polymorphisms (rs2393799, rs7958311, and rs3751143). Haplotype analysis indicated that P2X7R rs1718119A-rs2230911G-rs3751143C appeared to be a significant risk haplotype with obesity (P = 0.0005, OR 2.37, 95% CI 1.45-3.90).

CONCLUSIONS

P2X7R functional genetic polymorphisms and their estimated haplotypes are associated with obesity in Chinese postmenopausal women.

Molecular Cloning and Expression of Osmotin in a Baculovirus-Insect System: Purified Osmotin Mitigates Amyloid-beta Deposition in Neuronal Cells

Osmotin is a pathogenesis-related plant protein, have gained focus of research because of its homology with mammalian adiponectin. The therapeutic properties of osmotin have been explored in recent years as it exhibits neuroprotective effects against amyloid beta-, glutamate- and ethanol-induced synaptic dysfunction and neurodegeneration. In the present study, the full-length gene of the tobacco plant osmotin was cloned and expressed in the Sf9 insect cell line using the baculovirus expression system. In vitro analysis of purified Osmotin protein showed excellent cell viability, p-AMPK activation and a reduction in amyloid-beta deposition. Immunofluorescent analysis showed significant reduction in amyloid beta deposition in APP over expressing neuronal cells. Osmotin inhibited amyloid beta deposition by influencing expression of APP processing genes including APP, ADAM 10 and BACE 1. Purified Osmotin showed reduction in amyloid beta deposition in different in vitro models as well. Osmotin showed similar mechanism when compared with mammalian adiponectin in different in vitro models. The present method will be an excellent approach for the efficient and cost-effective production of the functional protein to be utilized for therapeutic purposes. Reduction in amyloid beta deposition by activation of p-AMPK influencing APP processing genes makes osmotin a potent therapeutic candidate for neurodegenerative diseases.

The P2X7 receptor is an upstream regulator of dynamic blebbing and a pluripotency marker in human embryonic stem cells

New methods are needed to reduce dynamic blebbing which inhibits cell attachment and survival during passaging of pluripotent stem cells. We tested the hypothesis that activation of the P2X7 receptor by extracellular ATP during passaging initiates dynamic blebbing. The P2X7 receptor was present in human embryonic stem cells (hESC), but not in differentiating cells. Extracellular ATP concentrations were 14× higher in medium during passaging. Addition of ATP to culture medium prolonged dynamic blebbing and inhibited attachment. Inhibition of P2X7 by specific drugs or by siRNA significantly reduced dynamic blebbing and improved cell attachment. When cells were incubated in calcium chelators (EGTA or BAPTA), blebbing decreased and attachment improved. Calcium influx was observed using Fura-4 when ATP was added to culture medium and inhibited in the presence of the P2X7 inhibitor. Over-expressing activated Rac in hESC reduced blebbing and promoted cell attachment, while a Rac inhibitor prolonged blebbing and reduced attachment. These data identify a pathway involving P2X7 that initiates and prolongs dynamic blebbing during hESC passaging. This pathway provides new insight into factors that increase dynamic blebbing and identifies new targets, such as P2X7, that can be used to improve the culture of cells with therapeutic potential.

The Role of the P2X7 Receptor in Ocular Stresses: A Potential Therapeutic Target

The P2X7 receptor is expressed in both anterior and posterior segments of the eyeball. In the ocular surface, the P2X7 receptor is activated in case of external aggressions: preservatives and surfactants induce the activation of P2X7 receptors, leading to either apoptosis, inflammation, or cell proliferation. In the retina, the key endogenous actors of age-related macular degeneration, diabetic retinopathy, and glaucoma act through P2X7 receptors’ activation and/or upregulation of P2X7 receptors’ expression. Different therapeutic strategies aimed at the P2X7 receptor exist. P2X7 receptor antagonists, such as divalent cations and Brilliant Blue G (BBG) could be used to target either the ocular surface or the retina, as long as polyunsaturated fatty acids may exert their effects through the disruption of plasma membrane lipid rafts or saffron that reduces the response evoked by P2X7 receptor stimulation. Treatments against P2X7 receptor activation are proposed by using either eye drops or food supplements.

Comparison of the effects of major fatty acids present in the Mediterranean diet (oleic acid, docosahexaenoic acid) and in hydrogenated oils (elaidic acid) on 7-ketocholesterol-induced oxiapoptophagy in microglial BV-2 cells

Increased levels of 7-ketocholesterol (7KC), which results mainly from cholesterol auto-oxidation, are often found in the plasma and/or cerebrospinal fluid of patients with neurodegenerative diseases and might contribute to activation of microglial cells involved in neurodegeneration. As major cellular dysfunctions are induced by 7KC, it is important to identify molecules able to impair its side effects. Since consumption of olive and argan oils, and fish is important in the Mediterranean diet, the aim of the study was to determine the ability of oleic acid (OA), a major compound of olive and argan oil, and docosahexaenoic acid (DHA) present in fatty fishes, such as sardines, to attenuate 7KC-induced cytotoxic effects. Since elaidic acid (EA), the trans isomer of OA, can be found in hydrogenated cooking oils and fried foods, its effects on 7KC-induced cytotoxicity were also determined. In murine microglial BV-2 cells, 7KC induces cell growth inhibition, mitochondrial dysfunctions, reactive oxygen species overproduction and lipid peroxidation, increased plasma membrane permeability and fluidity, nuclei condensation and/or fragmentation and caspase-3 activation, which are apoptotic characteristics, and an increased LC3-II/LC3-I ratio, which is a criterion of autophagy. 7KC is therefore a potent inducer of oxiapoptophagy (OXIdation+APOPTOsis+autoPHAGY) on BV-2 cells. OA and EA, but not DHA, also favor the accumulation of lipid droplets revealed with Masson's trichrome, Oil Red O, and Nile Red staining. The cytotoxicity of 7KC was strongly attenuated by OA and DHA. Protective effects were also observed with EA. However, 7KC-induced caspase-3 activation was less attenuated with EA. Different effects of OA and EA on autophagy were also observed. In addition, EA (but not OA) increased plasma membrane fluidity, and only OA (but not EA) was able to prevent the 7KC-induced increase in plasma membrane fluidity. Thus, in BV-2 microglial cells, the principal fatty acids of the Mediterranean diet (OA, DHA) were able to attenuate the major toxic effects of 7KC, thus reinforcing the interest of natural compounds present in the Mediterranean diet to prevent the development of neurodegenerative diseases.

Targeting the P2X7 Receptor in Age-Related Macular Degeneration

The P2X7 receptor (P2X7R) is a membrane receptor for the extracellular adenosine triphosphate (ATP). It functions as a ligand-gated non-selective cation channel and can mediate formation of a large non-selective membrane pore. Activation of the P2X7R induces multiple downstream events, including oxidative stress, inflammatory responses and cell death. Although the P2X7R has been identified in the retinal pigment epithelium (RPE) and different layers of retina, its biological and pathological functions as well as its downstream signaling pathways in the RPE and retina are not yet fully understood. Better understanding of the function of P2X7R in the RPE and retina under normal and disease states might lead to novel therapeutic targets in retinal diseases, including age-related macular degeneration (AMD). This brief review will mainly focus on recent findings on in vitro and in vivo evidence for the role of the P2X7R in the RPE and AMD.

A fast and reproducible cell- and 96-well plate-based method for the evaluation of P2X7 receptor activation using YO-PRO-1 fluorescent dye

The YO-PRO-1 assay provides a quantitative estimation of P2X7 receptor activation. P2X7 receptor is associated to pathological conditions including infectious, inflammatory, neurological, musculoskeletal disorders, pain and cancer. Most primary cells and cell lines from diverse origin may be used thanks to the ubiquitous distribution of P2X7 receptor. To study the activation of P2X7 receptor by chemicals or biological agents, we established a microplate-based cytometry protocol to accurately and rapidly quantify the activation of P2X7 receptor that leads to the formation of large pores in cell membranes. The YO-PRO-1 assay is based on the ability of cells to incorporate and bind YO-PRO-1 dye to DNA after activation of P2X7 receptor through pore formation. Cells are seeded in 96-well plates and incubated with the compound being tested for the appropriate time. The microplate is then incubated for 10 min with YO-PRO-1 staining solution. After the 10 min staining time, fluorescence signal is read using a microplate reader in 1 min. This procedure is easier and requires less handling steps than flow cytometry. 96-well plate based YO-PRO-1 assay is a reproducible and fast method to study both P2X7 receptor activation by toxic agents at subnecrotic concentrations and P2X7 receptor inhibition by antagonists.