Purinergic Signalling最新文献

Adenosine is a key modulator in the pathophysiology of acute kidney injury (AKI), particularly through its influence on inflammatory pathways and renal hemodynamics. This nucleoside exerts its effects via four G protein-coupled receptors-A1, A2A, A2B, and A3-each displaying distinct roles during renal injury. The A1 receptor primarily protects renal tissue under ischemic conditions by reducing metabolic demand, while the A2A receptor promotes anti-inflammatory and vasodilatory effects, improving renal perfusion and attenuating leukocyte infiltration. The A2B receptor, upregulated under hypoxic or injury conditions, is involved in anti-inflammatory actions and vascular integrity, especially in renal tubular and endothelial cells. Conversely, activation of the A3 receptor is generally linked to adverse outcomes, including increased apoptosis and greater tissue damage. Therapeutic strategies targeting adenosine receptors are being actively explored: selective A1 and A2A agonists show potential for promoting renal recovery, while A3 antagonists helped counteract the harmful effects of A3 activation. The review also discusses advances from recent studies (2022-2024), including insights on COVID-19-associated AKI and the nuanced roles of A1 and A3 receptors in different pathological contexts. Additionally, the therapeutic promise of inhibiting adenosine-degrading enzymes, such as ADA and adenosine kinase (ADK), is highlighted. Novel mechanistic insights and recent literature are integrated, providing a comprehensive overview that expands upon previous reviews. Although adenosine receptor modulation holds significant promise as a therapeutic strategy for AKI, further clinical research is necessary to validate efficacy and safety in human populations.

Periodontal disease (PD) is characterized by the presence of a chronic inflammatory process, due to the accumulation of bacterial biofilm and the host's response to these pathogens, resulting in the destruction of the supporting tissues of dental structures. Studies have revealed that components of the purinergic system and inflammation are related to the development and progression of PD. The objective was to evaluate periodontal clinical parameters, modulation of the purinergic system and inflammation in patients with PD, compared to individuals without the disease. This is a cross-sectional study with 25 healthy individuals (CT group) and 57 individuals with PD, where blood and saliva collection and isolation of blood components were carried out. The results showed that there was a significant reduction in the hydrolysis of adenosine triphosphate (ATP; p < 0.0001), adenosine diphosphate (ADP; p < 0.05) and adenosine monophosphate (AMP; p < 0.01) in peripheral blood mononuclear cells (PBMCs) from individuals in the PD group compared to the CT group, indicating that individuals with PD showed reduced NTPDase 1 and Ecto-5'-nucleotidase activity. Adenosine deaminase activity in saliva (p < 0.0001) and serum p < 0.05) from individuals with PD were significantly higher compared to the CT group. Extracellular ATP and the serum concentration of C-Reactive Protein showed a statistically significant increase in the PD group ((p < 0.0001 and p < 0.001, respectively). Therefore, the enzymes of the purinergic system are present in the modulation of PD, leading individuals affected by the disease to a pro-inflammatory state, hindering the action of the immune system and increasing serum markers of inflammation.

The P2X7 receptor is an adenosine triphosphate (ATP)-gated ion channel expressed in different cell types of the brain. Polymorphisms in the P2RX7 gene have repeatedly been associated with psychiatric disorders including major depression. Depression is a stress-related disorder in which a dysregulation of the immune system has attracted increasing attention as a potential disease mechanism. The well-documented role of P2X7 in inflammatory conditions advocates its involvement in immune system dysregulation and depression genesis. However, understanding its exact role requires further research using appropriate animal models. Unfortunately, some of the most widely used P2X7 knockout mouse models are limited in their utility by the continuous expression of certain P2rx7 splice variants or even activation of de novo transcripts. To overcome this limitation, we generated a novel constitutive and complete P2X7 KO mouse line. These KO mice lack all known murine splice variants and protein expression resulting in a loss-of-function as confirmed by calcium imaging and by the inability of P2X7-deficient peritoneal macrophages to mount an appropriate interleukin (IL)-1β response. Comprehensive characterization using a battery of tests assessing locomotion, anxiety- and depression-related as well as social behaviour revealed differences in locomotor and exploratory behaviours. P2X7 KO mice showed slightly increased locomotor activity and reduced anxiety-related behaviour at baseline. Under conditions of chronic stress exposure, genotype-dependent differences largely dissolved while P2X7 deficiency promoted enhanced stress resilience with regard to social behaviour. Taken together, our findings add further evidence for an involvement of the P2X7 in shaping different behavioural responses and their modulation by stressful environments. This novel loss-of-function model will contribute to a better understanding of P2X7 in stress-associated behaviours in basic and translational neuropsychiatric research.

Hemorrhagic shock (HS) leads to systemic hypoperfusion, impaired tissue oxygenation, and multi-organ dysfunction, including central nervous system (CNS) injury. Guanosine and inosine, purine nucleosides with neuroprotective and anti-inflammatory properties, have demonstrated beneficial effects in models of neurotoxicity, ischemia, and septic shock. This study evaluated the acute effects of guanosine and inosine in fluid resuscitation, focusing on brain energy metabolism, neuroinflammatory mechanisms, and hemodynamic responses in a porcine model of HS. Thirty pigs (25-30 kg) underwent controlled hemorrhage to achieve a target mean arterial pressure (MAP) of 40 - 45 mmHg, maintained for 60 min. Animals were randomized into three resuscitation groups: Lactated Ringer's solution (LR), LR + guanosine (1 mmol/L), and LR + inosine (1 mmol/L), administered over 15 - 20 min. Hemodynamic, metabolic, and neuronal parameters were monitored for 440 min post-HS, with serial blood and cerebrospinal fluid (CSF) sampling to assess glutamate, lactate, glucose, neuron-specific enolase (NSE), and inflammatory cytokines. HS induced metabolic acidosis, increased CSF glutamate levels, and elevated proinflammatory cytokines (IL-1β, TNF-α, IFN-γ, IL-8). Guanosine and inosine reduced glutamate levels more rapidly than LR alone and attenuated IL-1β and TNF-α elevations. Inosine resuscitation improved MAP, systemic vascular resistance index (SVRI), and end-diastolic volume index (EDVI), suggesting enhanced hemodynamic stabilization. Guanosine and inosine modulated neuroinflammatory and metabolic responses in HS, reducing excitotoxicity and inflammatory cytokine release. Inosine also demonstrated hemodynamic benefits. These findings support further investigation into their therapeutic potential in shock resuscitation.

Hormonal contraceptives, one of the most widely used contraceptive methods, are associated with the development of thromboembolism. Purinergic mediators such as soluble agonists, ectonucleotidases, and receptors play a prominent role in regulating hemostasis. This study aimed to evaluate E-NTPDase, E-5'-NT, and E-ADA activities in lymphocytes and platelets from women using combined oral contraceptives. Participants used third-generation (3G) oral contraceptives, such as drospirenone or cyproterone acetate, or fourth-generation (4G) oral contraceptives, such as gestodene or desogestrel, both combined with ethinylestradiol. The findings indicated decreased adenosine (ADO) deamination in lymphocytes (78%, p < 0.001) and decreased AMP hydrolysis (69%, p < 0.01) and ADO deamination (66%, p < 0.001) in platelets from women using 3G contraceptives compared with the control. Furthermore, the results showed decreased ADO deamination (66%, p < 0.05) in lymphocytes and decreased ATP hydrolysis (52%, p < 0.05) and decreased ADO deamination (57%, p < 0.001) in platelets from women using 4G contraceptives compared with the control. The observed patterns of AMP hydrolysis are compatible with an ADO-poor vascular microenvironment. Likewise, the decrease in E-ADA activity may be associated with lower concentrations of ADO in the vascular microenvironment, which has antiplatelet and anti-inflammatory effects. Overall, the findings demonstrated that hormonal contraceptives alter the activity of purinergic ectoenzymes, which might be related to their effects on hemostasis and a predisposition to thromboembolic events.

This Journal Club article discusses a recent study by López-Cano and collaborators, published in Journal of the American Chemical Society (López-Cano et al. Pharmacol Res 170:105731, 2021), which introduces a pioneering therapeutic approach for psoriasis based on systemic administration of a photoswitchable adenosine A₃ receptor (A₃R) agonist, MRS7787, to counteract psoriasis-relate skin alterations by topic exposure to light. The study presents a synthesis strategy, photochemical characterization, and functional evaluation of the compound, which provides light-controlled relief from IL-23-induced psoriatic skin lesions in the mouse ear, a corroborated animal model of psoriasis. The innovation offers insights into localized, time-specific, and reversible modulation of G protein-coupled receptor (GPCR) activity and has implications for drug discovery and optopharmacology, highlighting their potential for new strategies in treating skin-related diseases.

Endometriosis is a chronic gynecological condition characterized by endometrial tissue outside the uterine cavity. Recent research has focused on the relationship between the purinergic system and endometriosis. As a purinergic system component, extracellular adenosine triphosphate (ATP) has been involved as a crucial mediator of chronic pain associated with the disease, as well as P2X3 receptors, which play a key role in sensitization of nerve fibers and generation of nociceptive, neuropathic, and inflammatory pain. In addition, ectonucleotidases such as CD39 and CD73, which regulate ATP hydrolysis, have an altered expression in endometriotic lesions, contributing to extracellular ATP accumulation, intensifying inflammation and pain. Together, immune cells and their product are increased in endometriotic foci and promote the emergence of new lesions through their contribution to retrograde menstruation. Some studies have observed significant changes in mitochondrial respiration, notably decreased oxygen consumption in the affected endometrium. These various cellular processes that are mediated by ATP and adenosine in the uterine cavity and exert effects on immune defense will be herein reviewed in detail to investigate possible inhibitors, their activity, and potential exploration of the purinergic pathway as a therapeutic alternative.