Vitamin D3 mitigates type 2 diabetes induced by a high carbohydrate-high fat diet in rats: Role of the purinergic system.

This study evaluated the effect of vitamin D3 (VIT D3) supplementation on the enzymatic activities and density of ectonucleoside triphosphate diphosphohydrolase (E-NTPDase), ecto-5-nucleotidase (E-5'-NT), adenosine deaminase (ADA), as well as the density of P2 × 7R, P2Y12R, A1R, A2AR receptors, IL-1ß, and oxidative parameters in type 2 diabetic rats. Forty male Wistar rats were fed a high carbohydrate-high fat diet (HCHFD) and received an intraperitoneal injection containing a single dose of streptozotocin (STZ, 35 mg/kg). Animals were divided into four groups: 1) control; 2) control/VIT D3 12 µg/kg; 3) diabetic; and 4) diabetic/VIT D3 12 µg/kg. Results show that VIT D3 reduced blood glucose, ATP hydrolysis, ADA activity, P2Y12R density (platelets), as well as ATP, ADP, and AMP hydrolysis and ADA activity (synaptosomes). Moreover, VIT D3 increased insulin levels and AMP hydrolysis (platelets) and improved antioxidant defense. Therefore, we suggest that VIT D3 treatment modulates hyperglycemia-induced changes via purinergic enzymes and receptor expression, consequently attenuating insulin homeostasis dysregulation in the diabetic state.

Purinergic signaling influences the neuroinflammatory outcomes of a testosterone-derived synthetic in female rats: Resistance training protective effects on brain health.

Physical exercise is recognized as a non-pharmacological approach to treat and protect against several neuroinflammatory conditions and thus to prevent brain disorders. However, the interest in ergogenic resources by athletes and bodybuilding practitioners is widespread and on the rise. These substances shorten the process of performance gain and improve aesthetics, having led to the prominent use and abuse of hormones in the past years. Recent evidence has shown that the purinergic system, composed of adenine nucleotides, nucleosides, enzymes, and receptors, participates in a wide range of processes within the brain, such as neuroinflammation, neuromodulation, and cellular communication. Here, we investigated the effects of the anabolic androgenic steroid (AAS) testosterone (TES) at a dose of 70 mg/kg/week in female rats and the neuroprotective effect of resistance exercise related to the purinergic system and oxidative stress parameters. Our findings showed a decrease in ATP and ADO hydrolysis in treated and trained animals. Furthermore, there was an increase in the density of purinoceptors (P2X7 and A2A) and inflammatory markers (IBA-1, NRLP3, CASP-1, IL-1ß, and IL-6) in the cerebral cortex of animals that received AAS. On the other hand, exercise reversed neuroinflammatory parameters such as IBA-1, NLRP3, CASP-1, and IL-1ß and improved antioxidant response and anti-inflammatory IL-10 cytokine levels. Overall, this study shows that the use of TES without indication or prescription disrupts brain homeostasis, as demonstrated by the increase in neuroinflammation, and that the practice of exercise can protect brain health.

Resistance physical exercise alleviates lipopolysaccharide-triggered neuroinflammation in cortex and hippocampus of rats via purinergic signaling.

Resistance physical exercise has neuroprotective and anti-inflammatory effects on many known diseases and, therefore, it has been increasingly explored. The way in which this type of exercise exerts these actions is still under investigation. In this study, we aimed to analyze the enzymes and components of the purinergic system involved in the inflammatory process triggered by the P2X7R. Rats were divided into four groups: control, exercise (EX), lipopolysaccharide (LPS), and EX + LPS. The animals in the exercise groups were subjected to a 12-week ladder-climbing resistance physical exercise and received LPS after the last session for sepsis induction. Enzymes activities (NTPDase, 5'-nucleotidase, and adenosine deaminase), purinoceptors' density (P2X7R, A1, and A2A), and the levels of inflammatory indicators (pyrin domain-containing protein 3 (NLRP3), Caspase-1, interleukin (IL)- 6, IL-1B, and tumor necrosis factor (TNF) -α) were measured in the cortex and hippocampus of the animals. The results show that exercise prevented (in the both structures) the increase of: 1) nucleoside-triphosphatase (NTPDase) and 5'-nucleotidase activities; 2) P2X7R density; 3) NLRP3 and Caspase-1; and 4) IL-6, IL-1ß, and TNF-α It is suggested that the purinergic system and the inflammatory pathway of P2X7R are of fundamental importance and influence the effects of resistance physical exercise on LPS-induced inflammation. Thus, the modulation of the P2X7R by resistance physical exercise offers new avenues for the management of inflammatory-related illnesses.

Caffeic acid attenuates neuroinflammation and cognitive impairment in streptozotocin-induced diabetic rats: Pivotal role of the cholinergic and purinergic signaling pathways.

The present study evaluated the effect of caffeic acid (CA) on behavioral learning and memory tasks in the diabetic state. We also evaluated the effect of this phenolic acid on the enzymatic activities of acetylcholinesterase, ecto-nucleoside triphosphate diphosphohydrolase, ecto-5-nucleotidase and adenosine deaminase as well as on the density of M1R, α7nAChR, P2×7R, A1R, A2AR, and inflammatory parameters in the cortex and hippocampus of diabetic rats. Diabetes was induced by a single intraperitoneal dose of streptozotocin (55 mg/kg). The animals were divided into six groups: control/vehicle; control/CA 10 and 50 mg/kg; diabetic/vehicle; diabetic/CA 10 and 50 mg/kg, treated by gavage. The results showed that CA improved learning and memory deficits in diabetic rats. Also, CA reversed the increase in acetylcholinesterase and adenosine deaminase activities and reduced ATP and ADP hydrolysis. Moreover, CA increased the density of M1R, α7nAChR, and A1R receptors and reversed the increase in P2×7R and A2AR density in both evaluated structures. In addition, CA treatment attenuated the increase in NLRP3, caspase 1, and interleukin 1ß density in the diabetic state; moreover, it increased the density of interleukin-10 in the diabetic/CA 10 mg/kg group. The results indicated that CA treatment positively modified the activities of cholinergic and purinergic enzymes and the density of receptors, and improved the inflammatory parameters of diabetic animals. Thus, the outcomes suggest that this phenolic acid could improve the cognitive deficit linked to cholinergic and purinergic signaling in the diabetic state.

Neuromodulatory effect of the combination of metformin and vitamin D3 triggered by purinergic signaling in type 1 diabetes induced-rats.

Several studies have indicated the vitamin D deficiency in the development of macro- and microvascular complications of diabetes mellitus (DM) including DM-related cognitive dysfunction. The purinergic system plays an important role in the modulation of a variety of mechanisms, including neuroinflammation, plasticity, and cell-cell communication. In addition, purines, their receptors, and enzymes can regulate the purinergic axis at different levels in type 1 DM (T1DM). This study evaluated the effects of vitamin D3 alone or in combination with metformin in the behavioral performance of streptozotocin-induced T1DM rats. The effects of this combination on the metabolism of ATP and ADP were also studied by NTPDase (CD39), AMP by 5'-nucleotidase (CD73), and adenosine by adenosine deaminase (E-ADA) in the brain and peripheral lymphocytes of type 1 diabetic STZ-induced rats. The results showed that anxiety and memory loss from the DM condition reverted after 30 days of vitamin D3 treatment. Furthermore, the DM state affected systemic enzymes, with no effect on the central enzymes hydrolyzing extracellular nucleotides and nucleosides. Vitamin D3 treatment positively regulated ectonucleotidase (NTPDase and 5'-nucleotidase) activity, E-ADA, and the purinergic receptors as a mechanism to prevent oxidative damage in the cerebral cortex of T1DM rats. A neuroprotector effect of vitamin D3 through adenosine signaling was also observed, by regulating A1 and A2A receptors proteins levels. The present findings suggest that purinergic signaling through vitamin D3 modulation may be a novel alternative strategy for T1DM treatment, and may compensate for the negative changes in the central nervous system.

Superoxide-imbalance Pharmacologically Induced by Rotenone Triggers Behavioral, Neural, and Inflammatory Alterations in the Eisenia fetida Earthworm.

BACKGROUND: Some studies have suggested that mitochondrial dysfunction and a superoxide imbalance could increase susceptibility to chronic stressful events, contributing to the establishment of chronic inflammation and the development of mood disorders. The mitochondrial superoxide imbalance induced by some molecules, such as rotenone, could be evolutionarily conserved, causing behavioral, immune, and neurological alterations in animals with a primitive central nervous system. OBJECTIVE: Behavioral, immune, and histological markers were analyzed in Eisenia fetida earthworms chronically exposed to rotenone for 14 days. METHODS: Earthworms were placed in artificial soil containing 30 nM of rotenone distributed into a plastic cup that allowed the earthworms to leave and return freely into the ground. Since these organisms prefer to be buried, the model predicted that the earthworms would necessarily have to return to the rotenone-contaminated medium, creating a stressful condition. The effect on survival behavior in the immune and histological body wall and ventral nervous ganglia (VNG) structures, as well as gene expression related to inflammation and mitochondrial and neuromuscular changes. RESULTS: Rotenone-induced loss of earthworm escape behavior and immune alterations indicated a chronic inflammatory state. Some histological changes in the body wall and VNG indicated a possible earthworm reaction aimed at protecting against rotenone. Overexpression of the nicotinic acetylcholine receptor gene (nAChR α5) in neural tissues could also help earthworms reduce the degenerative effects of rotenone on dopaminergic neurons. CONCLUSION: These data suggest that mitochondrial dysfunction could be an evolutionarily conserved element that induces inflammatory and behavioral changes related to chronic stress.

High levels of extracellular ATP lead to different inflammatory responses in COVID-19 patients according to the severity.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has significantly impacted the world and has driven many researchers into the pathophysiology of COVID-19. In the findings, there is a close association between purinergic signaling and the immune response. Then, this study aimed to evaluate alterations in the purinergic signaling in COVID-19 patients according to range severity. We divided the COVID-19 patients into moderate and severe cases following the guideless of NIH and WHO, together with clinical characteristics. The blood samples were collected to obtain PBMCs and platelets. We analyzed the ectonucleotidase activities through ATP, ADP, AMP, Ado hydrolysis, E-NTPDase1 (CD39), and 5'-NT (CD73) expression by flow cytometry in total leukocytes. The extracellular ATP was measured by bioluminescence, and cytokines were analyzed by flow cytometry. We observed a decrease in ATP hydrolysis and increased AMP hydrolysis in PBMCs for both groups. In severe cases, ATP hydrolysis was raised for the platelets, while ADP and AMP hydrolysis have risen significantly in both groups. Additionally, there was a significant increase in ADP hydrolysis in severe cases compared to moderate cases. In addition, we observed an increase in the ADA activity in platelets of moderate patients. Moderate and severe cases showed increased expression of CD39 and CD73 in total leukocytes. To finalize the purinergic signaling, extracellular ATP was increased in both groups. Furthermore, there was an increase in IL-2, IL-6, IL-10, and IL-17 in moderate and severe groups. Thus, for the first time, our findings confirm the changes in purinergic signaling and immune response in COVID-19, in addition to making it more evident that the severity range directly impacts these changes. Therefore, the therapeutic potential of the purinergic system must be highlighted and studied as a possible target for the treatment of SARS-CoV-2 disease. KEY MESSAGES: COVID-19 patients exhibit alterations in purinergic system and immune response. High levels of extracellular ATP lead to different inflammatory responses. CD39 and CD73 expression were increased in COVID-19 patients. Cytokines IL-2, IL-6, IL-10, and IL-17 also were altered in these patients. The purinergic system may be a possibility target to SARS-CoV-2 treatments.

Berberine increases the expression of cytokines and proteins linked to apoptosis in human melanoma cells.

BACKGROUND: Melanoma is the most lethal form of skin cancer, and its incidence has increased considerably in the last decades. Melanoma presents difficult treatment with strong resistance of tumor cells, due to its extremely invasive nature with high capacity to metastases. Berberine (BBR), an isoquinoline alkaloid, is a molecule found in several medicinal plants, and has been studied in several diseases, demonstrating antimicrobial, antidiabetic and anti-inflammatory properties and anti-tumorigenic effects. METHODS AND RESULTS: In SK-MEL-28 cells, 50 µM BBR treatment for 24 h decreased cell viability by 50 percent. This concentration generated cell death both by early apoptosis and necrosis, with an increase in the DNA damage index. BBR increased (*p < 0.05) the proportion of cells in G1/G0 phase and decreased (###p < 0.005) the percentage of cells in S phase. The alcaloid increased (****p < 0.001) ROS production compared to untreated controls with an increase in activated caspase 3 and phosphorylated p53 protein levels. In addition, BBR significantly enhanced ERK as well as both pro- and anti-inflammatory cytokine expression compared to untreated controls. CONCLUSIONS: BBR has important antiproliferative effects and may be alone or in adjunct therapy a promising candidate for melanoma treatment, a cancer with great incidence and high lethality.

Amazon-derived nutraceuticals: Promises to mitigate chronic inflammatory states and neuroinflammation.

Nutraceuticals have been the focus of numerous research in recent years and accumulating data support their use for promoting some health benefits. Several nutraceuticals have been widely studied as supplements due to their functional properties ameliorating symptoms associated with neurological disorders, such as oxidative stress and chronic inflammatory states. This seems to be the case of some fruits and seeds from the Amazon Biome consumed since the pre-Columbian period that could have potential beneficial impact on the human nervous system. The beneficial activities of these food sources are possibly related to a large number of bioactive molecules including polyphenols, carotenoids, unsaturated fatty acids, vitamins, and trace elements. In this context, this review compiled the research on six Amazonian fruits and seeds species and some of the major nutraceuticals found in their composition, presenting brief mechanisms related to their protagonist action in improving inflammatory responses and neuroinflammation.

Chlorpyrifos pesticide promotes oxidative stress and increases inflammatory states in BV-2 microglial cells: A role in neuroinflammation.

The exposure to environmental stressors, such as organophosphate (OP) pesticides, has been associated with the development of neurodegenerative diseases. Chlorpyrifos (CPF) is the worldwide most used OP pesticide and one of the most hazardous pesticides as it can cross the blood-brain barrier. Since studies evaluating the effects of CPF on brain immune cells are scarce, this research investigated the oxidative and inflammatory responses of CPF exposure in murine microglial cells. BV-2 cells were exposed to different concentrations of CPF pesticide (0.3-300 µM). CPF induced activation of microglial cells, confirmed by Iba-1 and CD11b marking, and promoted microglial proliferation and cell cycle arrest at S phase. Moreover, CPF exposure increased oxidative stress production (NO, MDA, and O2∙), and upregulated pro-inflammatory cytokines (IL-1ß and NLRP3) genes expression in BV-2 cells. Overall, data showed that CPF exposure, at the lowest concentrations, acted by promoting pro-oxidative and pro-inflammatory states in microglial cells. These results provide important information on the potential role of microglial activation in CPF-induced neuroinflammation and add to the expanding knowledge on the neurotoxicity of OP.

Modulatory effects of caffeic acid on purinergic and cholinergic systems and oxi-inflammatory parameters of streptozotocin-induced diabetic rats.

Diabetes mellitus (DM) is a metabolic disorder characterized by a chronic hyperglycemia state, increased oxidative stress parameters, and inflammatory processes. AIMS: To evaluate the effect of caffeic acid (CA) on ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase) and adenosine deaminase (ADA) enzymatic activity and expression of the A2A receptor of the purinergic system, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymatic activity and expression of the α7nAChR receptor of the cholinergic system as well as inflammatory and oxidative parameters in diabetic rats. METHODS: Diabetes was induced by a single dose intraperitoneally of streptozotocin (STZ, 55 mg/kg). Animals were divided into six groups (n = 10): control/oil; control/CA 10 mg/kg; control/CA 50 mg/kg; diabetic/oil; diabetic/CA 10 mg/kg; and diabetic/CA 50 mg/kg treated for thirty days by gavage. RESULTS: CA treatment reduced ATP and ADP hydrolysis (lymphocytes) and ATP levels (serum), and reversed the increase in ADA and AChE (lymphocytes), BuChE (serum), and myeloperoxidase (MPO, plasma) activities in diabetic rats. CA treatment did not attenuate the increase in IL-1ß and IL-6 gene expression (lymphocytes) in the diabetic state; however, it increased IL-10 and A2A gene expression, regardless of the animals' condition (healthy or diabetic), and α7nAChR gene expression. Additionally, CA attenuated the increase in oxidative stress markers and reversed the decrease in antioxidant parameters of diabetic animals. CONCLUSION: Overall, our findings indicated that CA treatment positively modulated purinergic and cholinergic enzyme activities and receptor expression, and improved oxi-inflammatory parameters, thus suggesting that this phenolic acid could improve redox homeostasis dysregulation and purinergic and cholinergic signaling in the diabetic state.

Tucumã (Astrocaryum aculeatum) Prevents Oxidative and DNA Damage to Retinal Pigment Epithelium Cells.

Eye diseases have a negative impact on the eyesight quality of the world population. The age-related macular degeneration (AMD) draws special attention since it is a chronic disorder characterized by oxidative and inflammatory damage to the retinal epithelial pigment, which triggers progressive vision loss. In the Brazilian Amazon, Astrocaryum aculeatum is an Amazonian fruit (Tucumã) used by riverside communities in traditional medicine to treat a number of ailments. These communities have recently shown to have increased longevity and reduced prevalence of age-related morbidity. Thus, the aim of this research was to chemically characterize and analyze the in vitro antioxidant effect and molecular damage prevention of the Tucumã ethanolic extract in retinal pigment epithelium (RPE) cells in a model for AMD. The extract was chemically characterized by ultra-high-performance liquid chromatography (HPLC) coupled with diode-array detection and mass spectrophotometry (HPLC-DAD-MS). In vitro protocols were performed, and the cytopreventive effect of Tucumã on RPE cells exposed to high concentrations of superoxide anion, an oxidant and genotoxic molecule, as well as the effect of Tucumã extract on oxidative and molecular makers were assessed. Biochemical and flow cytometry analyses were conducted in these protocols. The extract presents high concentrations of caffeic acid, gallic acid, catechin, luteolin, quercetin, and rutin. Treatment did not show cytotoxic effects in cells treated only with extract at 50 µg/mL. In fact, it improved cell viability and was able to prevent necrosis and apoptosis, and oxidative and molecular damage was significantly reduced. In summary, Tucumã is an important Amazon fruit, which seems to contribute significantly to improve human health conditions, as our findings suggest that its extract has a relevant chemical matrix rich in antioxidant molecules, and its consumption could improve eye health and contribute to prevention against oxidative stress through cytoprevention, reactive oxygen species reduction, and maintenance of DNA integrity in retinal pigment epithelium (RPE) cells.

Aluminum-Induced Alterations in Purinergic System Parameters of BV-2 Brain Microglial Cells.

Aluminum (Al) is ubiquitously present in the environment and known to be a neurotoxin for humans. The trivalent free Al anion (Al3+) can cross the blood-brain barrier (BBB), accumulate in the brain, and elicit harmful effects to the central nervous system (CNS) cells. Thus, evidence has suggested that Al increases the risk of developing neurodegenerative diseases, particularly Alzheimer's disease (AD). Purinergic signaling has been shown to play a role in several neurological conditions as it can modulate the functioning of several cell types, such as microglial cells, the main resident immune cells of the CNS. However, Al effects on microglial cells and the role of the purinergic system remain elusive. Based on this background, this study is aimed at assessing the modulation of Al on purinergic system parameters of microglial cells. An in vitro study was performed using brain microglial cells exposed to Al chloride (AlCl3) and lipopolysaccharide (LPS) for 96 h. The uptake of Al, metabolism of nucleotides (ATP, ADP, and AMP) and nucleoside (adenosine), and the gene expression and protein density of purinoceptors were investigated. The results showed that both Al and LPS increased the breakdown of adenosine, whereas they decreased nucleotide hydrolysis. Furthermore, the findings revealed that both Al and LPS triggered an increase in gene expression and protein density of P2X7R and A2AR receptors, whereas reduced the A1R receptor expression and density. Taken together, the results showed that Al and LPS altered the setup of the purinergic system of microglial cells. Thus, this study provides new insights into the involvement of the purinergic system in the mechanisms underlying Al toxicity in microglial cells.

Diabetes and hypertension: Pivotal involvement of purinergic signaling.

Diabetes mellitus (DM) and hypertension are highly prevalent worldwide health problems and frequently associated with severe clinical complications, such as diabetic cardiomyopathy, nephropathy, retinopathy, neuropathy, stroke, and cardiac arrhythmia, among others. Despite all existing research results and reasonable speculations, knowledge about the role of purinergic system in individuals with DM and hypertension remains restricted. Purinergic signaling accounts for a complex network of receptors and extracellular enzymes responsible for the recognition and degradation of extracellular nucleotides and adenosine. The main components of this system that will be presented in this review are: P1 and P2 receptors and the enzymatic cascade composed by CD39 (NTPDase; with ATP and ADP as a substrate), CD73 (5'-nucleotidase; with AMP as a substrate), and adenosine deaminase (ADA; with adenosine as a substrate). The purinergic system has recently emerged as a central player in several physiopathological conditions, particularly those linked to inflammatory responses such as diabetes and hypertension. Therefore, the present review focuses on changes in both purinergic P1 and P2 receptor expression as well as the activities of CD39, CD73, and ADA in diabetes and hypertension conditions. It can be postulated that the manipulation of the purinergic axis at different levels can prevent or exacerbate the insurgency and evolution of diabetes and hypertension working as a compensatory mechanism.

Moringa oleifera modulates cholinergic and purinergic enzymes activity in BV-2 microglial cells.

Microglia are immune cells that are resident in central nervous system. Activation of microglial cells are detrimental to the survival of neurons. Thus, prevention of microglia activation and/or protection against microglia activation could be potential therapeutic strategy towards the management of inflammation-mediated neurodegenerative diseases. Moringa oleifera is widely consumed as food and used in folklore medicine for treating several diseases. This study was convened to investigate the effect of aqueous extract of Moringa oleifera on cell viability, cholinergic and purinergic enzymes in BV-2 microglial cultured cell. Aqueous extract of Moringa oleifera was prepared, lyophilized and reconstituted in 0.5% dimethylsulphoxide (DMSO). Cells were treated with Moringa oleifera extracts (0.1-100 µg/mL) and assessed for cell viability and nitric oxide production. Furthermore, the effect of Moringa oleifera on enzymes of cholinergic (acetylcholinesterase) and purinergic (nucleoside triphosphate diphosphohydrolase; NTPDase, 5' nucleotidase and adenosine deaminase; ADA) systems in BV-2 microglial cells were determined. Incubation of BV-2 microglia cell with M. oleifera extract maintained cell viability, modulated cholinergic and purinergic enzymes activity. The phenolic compounds found in M. oleifera extracts, include chlorogenic acid, rutin; quercetin pentoside, kaempferol derivative and quercetin derivative. Thus, this study suggest that the potential therapeutic effect of the phenolic compounds found in M. oleifera may have been responsible for the maintenance of cell viability in BV-2 microglia cells and modulation of cholinergic as well as purinergic enzymes activity.

Superoxide-anion triggers impairments of immune efficiency and stress response behaviors of Eisenia fetida earthworms.

Superoxide-hydrogen peroxide (S-HP), triggered by Val16Ala-SOD2 human polymorphism, may influence the risk of depression. Therefore, it is plausible that higher basal S-anion levels and chronic inflammatory states associated with the VV-SOD2 genotype can negatively modulate the stress response associated with resilience in various species, from primitive species to humans. To test this hypothesis, Eisenia fetida earthworms were exposed for 24 h to 30 nM rotenone, which causes mitochondrial dysfunction by generating high S-anion levels (known as the "VV-like phenotype"), and 10 µM porphyrin, a SOD2-like compound, which generates elevated HP levels (known as the "AA-like phenotype"). The results suggested that both S-anion and HP acted as signaling molecules, differentially altering the immune function and acute hydric stressful response. Although the AA-like phenotype improved the immune and stress response efficiencies, the VV-like phenotype showed a downregulated expression of the toll-like receptor (EaTLR, JX898685) and antimicrobial peptide (AMP) (AF060552) genes, which triggered the impairment of encapsulation and earthworms extracellular trap (EET) processes used by earthworms to trap and destroy microorganisms. When exposed to adverse environments and dangerous hydric stress, VV-like earthworms exhibited an impulsive behavior and failed to quickly identify and migrate to a protected environment, unlike control earthworms and AA-like earthworms. All results corroborated that the S-anion imbalance could concomitantly induce alterations in immune function and stress behavior related to earthworm survival. From a human perspective, this information may corroborate the potential specific role of superoxide anion in the modulation of the stress response, resilience, and risk of depression.

Potential Therapeutic Role of Purinergic Receptors in Cardiovascular Disease Mediated by SARS-CoV-2.

Novel coronavirus disease 2019 (COVID-19) causes pulmonary and cardiovascular disorders and has become a worldwide emergency. Myocardial injury can be caused by direct or indirect damage, particularly mediated by a cytokine storm, a disordered immune response that can cause myocarditis, abnormal coagulation, arrhythmia, acute coronary syndrome, and myocardial infarction. The present review focuses on the mechanisms of this viral infection, cardiac biomarkers, consequences, and the possible therapeutic role of purinergic and adenosinergic signalling systems. In particular, we focus on the interaction of the extracellular nucleotide adenosine triphosphate (ATP) with its receptors P2X1, P2X4, P2X7, P2Y1, and P2Y2 and of adenosine (Ado) with A2A and A3 receptors, as well as their roles in host immune responses. We suggest that receptors of purinergic signalling could be ideal candidates for pharmacological targeting to protect against myocardial injury caused by a cytokine storm in COVID-19, in order to reduce systemic inflammatory damage to cells and tissues, preventing the progression of the disease by modulating the immune response and improving patient quality of life.

Unmetabolized quetiapine exerts an in vitro effect on innate immune cells by modulating inflammatory response and neutrophil extracellular trap formation.

Quetiapine is an antipsychotic drug that is used to treat psychiatric and neurological disorders. Despite its efficiency and low-toxicity, quetiapine administration has been associated with undesirable side effects such as the development of low-grade inflammatory disorders and neutropenia states. As the liver rapidly metabolizes quetiapine to metabolites, the non-metabolized part of this molecule might play a role in immune alterations. In an in vitro study, this hypothesis was tested by exposing activated and inactivated RAW-264.7 macrophages and human neutrophils to unmetabolized quetiapine (u-QUE). Based on our findings, u-QUE was not cytotoxic to these cells. u-QUE differentially modulates macrophages according to their activation states. In inactivated macrophages, u-QUE induced a proinflammatory state as observed by an increase in cellular proliferation; increased levels of oxidative molecules (nitric oxide and superoxide), protein levels, and gene overexpression of proinflammatory cytokines (IL-1ß, IL-6, and TNF-α); and decreased levels of IL-10, an anti-inflammatory cytokine. Conversely, on phytohemagglutinin (PHA)-activated macrophages, u-QUE exerted an anti-inflammatory effect. u-QUE induced neutrophil extracellular trap (NET) formation and increased the sensitivity of the neutrophils previously activated by exposure to dead yeast cells for NET formation. These results confirm the effect of quetiapine on macrophage and neutrophil function, which may be associated with the side effects of this psychopharmaceutical agent.

Neuroprotective role of resveratrol mediated by purinergic signalling in cerebral cortex of mice infected by Toxoplasma gondii.

The central nervous system of the intermediate host plays a central role in lifelong persistence of Toxoplasma gondii as well as the pathogenesis of congenital toxoplasmosis and reactivated infection in immunocompromised individuals. The purinergic system has been implicated in a wide range of immunological pathways for controlling intracellular responses to pathogens, including T. gondii. In the present study, we investigated the effect of resveratrol (RSV) on ectonucleotidases, adenosine deaminase (ADA), and purinergic receptors during chronic infection by T. gondii. For this study, Swiss mice were divided into control (CTL), resveratrol (RSV), infected (INF), and INF+RSV groups. The animals were orally infected with the VEG strain and treated with RSV (100 mg/kg, orally). Ectonucleotidase activities, P2X7, P2Y1, A1, and A2A purinergic receptor density, ROS, and thiobarbituric acid reactive substances levels were measured in the cerebral cortex of mice. T. gondii infection increased NTPDase and reduced ADA activities. Treatment with RSV also affected enzymes hydrolysing extracellular nucleotides and nucleosides. Finally, RSV affected P1 and P2 purinergic receptor expression during T. gondii infection. Overall, RSV-mediated beneficial changes in purinergic signalling and oxidative stress, possibly improving cerebral cortex homeostasis in T. gondii infection.