Purinergic Signalling最新文献

Purinergic signaling pathways play crucial roles in regulating hemostatic and inflammatory responses, both of which are impacted by scorpion envenomation. Scorpion venoms are complex mixtures of various toxins, such as peptides, enzymes, and nucleotides. Previous research showed that the action of scorpion toxins on the purinergic system stems from their effects on purinergic receptors. Additionally, a study identified a putative ectonucleotidase in scorpion venom. This study aimed to investigate the ability of Tityus confluens venom (10, 50, and 100 µg/mL) to metabolize adenine nucleotides and its potential effects on purinergic enzyme activity in rat platelets and lymphocytes. The effects of T. confluens venom on E-NTPDase (ATP and ADP hydrolysis), E-5'-NT (AMP hydrolysis), and E-ADA (ADO hydrolysis) activities were analyzed. The results revealed that crude venom from T. confluens exhibited ATP hydrolysis activity at all tested concentrations. In lymphocytes, ADP hydrolysis was inhibited by 100 µg/mL crude venom, whereas ADO hydrolysis was increased by all venom concentrations. In platelets, ATP hydrolysis was inhibited by 50 and 100 µg/mL crude venom, whereas AMP and ADO hydrolysis were inhibited by all concentrations. When considered collectively, the data suggested an elevation in extracellular ATP levels and a reduction in extracellular ADO. These findings are in alignment with clinical manifestations of scorpion envenomation characterized by a pro-inflammatory milieu. Furthermore, this study demonstrated the intrinsic ATPase activity of T. confluens venom and its ability to modulate E-NTPDase, E-5'-NT, and E-ADA activities in rat blood cells.

Hypochlorous acid (HOCl) is generated by neutrophils during the innate immune response. ATP is released from cells by various stimuli and during inflammation but whether ATP is released by and participates in the response to HOCl is unclear. This study investigated vasomotor effects of HOCl on the porcine coronary artery (PCA) and the involvement of ATP and purine receptors. HOCl at 100 μM induced rapid and transient endothelium-dependent relaxation followed by slow and sustained endothelium-independent relaxation. Transient endothelium-dependent relaxation was induced by 500 μM HOCl, followed by endothelium-dependent contraction, then slow endothelium-independent relaxation. 8-(p-sulphophenyl)theophylline (8-SPT), an adenosine/P1 receptor antagonist, blocked rapid relaxation and contraction to HOCl but an A_2A receptor antagonist, ZM 241385, and an A₁ receptor antagonist, DPCPX, had no effect. Suramin, a P2 receptor antagonist (and membrane channel inhibitor), blocked rapid relaxation (at 100 μM HOCl) and contraction to HOCl. Other antagonists for P2, P2X1, P2Y1 and P2X4 receptors (PPADS, reactive blue 2, NF449, MRS2179 and BX430) did not affect HOCl responses. Relaxation to exogenous ATP was inhibited by 8-SPT but not by suramin suggesting that suramin block of HOCl responses may involve inhibition of membrane channels and endogenous ATP release. Apyrase, which hydrolyzes nucleotides, abolished responses to HOCl, ATP and unexpectedly adenosine. Neither probenecid nor carbenoxelone (connexin and pannexin channel inhibitors) blocked responses to HOCl. Luminescent ATP assay showed that HOCl elicited ATP release from cultures of human coronary artery endothelial cells. These findings advance our understanding of inflammation by showing that HOCl evokes endothelium-dependent vasorelaxation and contraction in coronary arteries which may involve P1 receptors implicating endogenous adenosine, possibly generated from rapid metabolism of ATP released by HOCl.

Immunotherapies, such as immune checkpoint inhibitors (ICI), anti-cancer vaccines and adoptive T cell transfer, are promising treatments for cancer patients. However, ICI have not shown therapeutic benefit for most mismatch repair-proficient colorectal and pancreatic ductal adenocarcinoma tumors (PDAC), which are aggressive and deadly (Li et al. in Biomedicines 12:2175, 2024). Tumor metabolism can enhance immunological tolerance, but hinder immune cell function. In a recent publication in Nature Cancer, Scolaro et al. (Scolaro et al. in Nature Cancer 5:1206-1226, 2024) showed that cytidine deaminase (CDA) upregulation may play a crucial role in shaping the immunosuppressive landscape of human PDAC and other tumors. CDA targeting in pancreatic cancer cell lines led to reduced tumor growth, weight and total regression after treatment aimed at the programmed cell death protein 1 receptor (PD-1) immune checkpoint protein. CDA inhibition, both genetically and pharmacologically, overcame immunotherapy resistance in PDAC models. CDA targeting in PDAC cells altered the tumor microenvironment (TME), enabling T cells to respond to anti-PD-1. In mice with sgNT and sgCda tumors receiving anti-PD-1 treatment, they reduced the number of CD8⁺ T cells. CDA reduction in cancer cells makes tumors more sensitive to immunotherapy, presumably by overcoming immunosuppressive tumor-associated macrophages (TAMs) and forcing them to adopt an immunostimulatory phenotype. The study also found that cancer cells produce a TME rich in UDP (and UTP) by taking advantage of the CDA-mediated pyrimidine salvage pathway. This setting inhibits the recruitment and activation of CD8⁺ T cells by promoting the infiltration and immunosuppressive characteristics of P2Y₆ receptor-expressing TAMs.

Prostate cancer (PCa) preferentially metastasizes to bone, which remains incurable and contributes significantly to mortality and morbidity. The P2X4 receptor (P2X4R) is a receptor for ATP that is highly expressed in many cancer types including PCa and is positively associated with tumorigenesis. To understand the role of P2X4R in PCa biology, particularly in PCa bone metastasis, P2X4R (P2RX4) was knocked out in human PCa cell line PC3 cells using the CRISPR/Cas9 system. Cell proliferation, apoptosis, migration, and invasion were examined using CyQUANT, Cell Meter Caspase 3/7, scratch and transwell assays. Results showed that depleting P2X4R significantly reduced cell proliferation and invasion and increased apoptosis compared to PC3 wildtype (WT) controls in vitro. To test their metastatic potential in vivo, PC3 WT and knock-out (KO) cells were intracardiacally injected into male BALB/c immunocompromised mice. Twenty-five days post-injection, there were no detectable tumours and associated bone destruction in the tibias of mice injected with KO cells, whereas tibias of over 50% mice injected with WT cells were occupied by tumour cells, with significant bone destruction observed ex vivo using micro-CT. Furthermore, RNA-seq and bioinformatic analysis of P2X4R KO cells demonstrated links between P2X4R and PCa cell adhesion, and other key signalling such as Wnt signalling. These findings suggest that P2X4R is a potential therapeutic target for PCa metastasis, particularly bone metastasis.

Elevated interleukin-6 (IL-6) levels are linked to an increased risk of cardiovascular mortality in myocardial infarction (MI). Targeting IL-6 and its downstream signalling pathways represents a therapeutic strategy; however, its cellular sources and regulatory mechanisms of IL-6 remain incompletely understood. In this study, Alter and colleagues investigated the primary cell type that produces IL-6 in post-MI murine heart and the role of purinergic signalling in regulating IL-6 formation. Using cellular and mouse models, the authors identified cardiac fibroblasts as the predominant source of IL-6. Further analysis revealed that the IL-6 formation in cardiac fibroblasts is regulated by adenosine A_2B receptors. Of further importance, they elucidated that T cells highly express CD73, leading to significant adenosine formation, which in turn enhances IL-6 production via Gq activation in cardiac fibroblasts following MI. These findings reveal a dynamic interplay between immune cells and fibroblasts in shaping the post-MI inflammatory response. This study suggests the adenosine-A_2B receptor-IL6 axis as a potential therapeutic target to mitigate inflammation and improve cardiomyocytes salvage in MI.

More and more studies have revealed that P2 purinergic receptors play a key role in the progression of colorectal cancer (CRC). P2X and P2Y purinergic receptors can be used as promoters and regulators of CRC and play a dual role in the progression of CRC. CRC microenvironment is rich in ATP and its cleavage products (ADP, AMP, Ado), which act as activators of P2X and P2Y purinergic receptors. The activation of P2X and P2Y purinergic receptors regulates the progression of CRC mainly by regulating the function of immune cells and mediating different signal pathways. In this paper, we focus on the specific mechanisms and functional roles of P2X7, P2Y12, and P2Y2 receptors in the growth and progression of CRC. The antagonistic effects of these selective antagonists of P2X purinergic receptors on the growth, invasion, and metastasis of CRC were further discussed. Moreover, different studies have reported that P2X7 receptor can be used as an effective predictor of patients with CRC. All these indicate that P2 purinergic receptors are a key regulator of CRC. Therefore, antagonizing P2 purinergic receptors may be an innovative treatment for CRC.

P2X7 receptor (P2X7R) has been found to contribute to the peripheral mechanism of acupuncture analgesia (AA). However, whether it plays an important role in central mechanism remains unknown. In this study, we aimed to reveal the role of astrocytic P2X7R in retrosplenial cortex (RSC) in AA and provide new evidence for underlying the central mechanism of AA. We applied the chemogenetic receptors hM3Dq to stimulate or hM4Di to inhibit astrocytes ligand clozapine-N-oxide (CNO) following injection of adeno-associated virus (AAV) into the bilateral RSC, or pharmacologically intervened in the activity of the purinergic receptor P2X7R. Current data indicated that chemogenetic inhibition of astrocytes or injection of P2X7R agonist Bz-ATP in the bilateral RSC significantly reverses the analgesic effect of electroacupuncture (EA) in formalin tests while the bilateral injection of the P2X7R antagonist A438079 alleviated formalin-induced nociceptive behavior. Additionally, chemogenetic suppression of astrocytic P2X7R by injection of AAV in the bilateral RSC decreased hind paw flinches induced by formalin in the mice. These findings indicate the participation of both astrocytes and P2X7R in the RSC in EA analgesic. Moreover, P2X7R on astrocytes in the RSC appears to play a critical role in the ability of EA to attenuate formalin-induced pain responses in mice.

In a recent article published in Nature Communications (Shigetomi et al Nat Commun 15(1):6525, 2024), Shigetomi et al. identified that upregulated astrocytic purinergic P2Y₁ receptors (P2Y₁R), acting via the downstream molecule, insulin-like growth factor binding protein 2 (IGFBP2), play a crucial role in neuronal hyperexcitability. In epilepsy and stroke models, P2Y₁R-IGFBP2 signaling was found to mediate astrocyte-driven neuronal hyperexcitability and so is a new contributor to astrocyte-neuron communication. Thus, IGFBP2 could be an alternative target for treating the effects of upregulated P2Y₁R activity in reactive astrocytes in neurological diseases.