Role Of Extracellular Adenosine Triphosphate Research Articles

Extracellular ATP Contributes to Barrier Function and Inflammation in Atopic Dermatitis: Potential for Topical Treatment of Atopic Dermatitis by Targeting Extracellular ATP.

Atopic dermatitis (AD) is characterized by chronic inflammation, barrier dysfunction, and pruritus, exacerbated by external stimuli, such as scratching. This study investigates the role of extracellular adenosine triphosphate (ATP) in the pathophysiology of AD and assesses the therapeutic potential of clodronate, an ATP release inhibitor. Our research demonstrates that extracellular ATP impairs skin barrier function by reducing the filaggrin expression in the keratinocytes, a critical protein for barrier integrity. Furthermore, ATP release, triggered by IL-4 and mechanical stimuli, amplifies inflammation by promoting cytokine and chemokine production by the immune cells. Clodronate, by inhibiting ATP release, restores the filaggrin levels in the keratinocytes, reduces TARC production in the dendritic cells, and alleviates AD symptoms in a mouse model. These findings suggest that targeting extracellular ATP could offer a novel therapeutic approach to improving skin barrier function and reducing inflammation in AD. Future studies should explore the long-term efficacy and safety of ATP-targeted therapies in clinical settings.

Mentha piperita leaf extract suppresses the release of ATP from epidermal keratinocytes and reduces dermal thinning as well as wrinkle formation.

To achieve a more beautiful and younger appearance, reducing wrinkles is a key concern. The process of wrinkle formation is complex and the development of truly effective cosmetic ingredients to reduce wrinkles remains a challenge. Recent studies have revealed a close relationship between wrinkles and skin thinning, suggesting that preventing skin thinning could also prevent wrinkle formation. In this study, we examined the role of extracellular adenosine triphosphate (eATP) in the progression of thinning, as eATP reportedly increases skin ageing factors, such as senescence-associated secreted phenotype (SASP) factors in epidermal cells. We determined the effects of Mentha piperita leaf extract on suppressing eATP to reduce thinning and wrinkles. Adenosine triphosphate (ATP) levels were measured in normal human epidermal keratinocytes (NHEK) in the presence of M. piperita leaf extract. Dryness, high pH, and UVB radiation were used as extrinsic ageing factors. Intrinsic skin ageing was evaluated by comparing cells from adults (AD-NHEK) and newborns (NB-NHEK). A placebo-controlled invivo study was carried out with a formulation containing 1% M. piperita leaf extract. The eATP levels were significantly higher in AD-NHEK compared with that in NB-NHEK cells. M. piperita leaf extract significantly decreased eATP levels in adult cells. Extrinsic ageing factors increased eATP levels in NHEK, whereas M. piperita leaf extract significantly suppressed eATP under all conditions. The active components of M. piperita leaf extract, luteolin glucuronide and rosmarinic acid, also decreased eATP. Moreover, compared with placebo lotion, M. piperita leaf extract-formulated lotion markedly increased dermal thickness and reduced wrinkles associated with crow's feet and the neck area. We demonstrated for the first time that M. piperita leaf extract containing rosmarinic acid and luteolin-7-O-glucuronide has the potential to reduce eATP release from epidermal keratinocytes. An increase in eATP was observed not only during inflammation but also during natural ageing. Furthermore, the invivo experiment revealing that 1% M. piperita leaf extract-containing lotion improved dermal thinning and wrinkles across multiple areas is attributed to the amelioration of dermal thinning. Thus, our data suggest the possibility of a novel cosmetic approach for reducing skin ageing by reducing eATP-mediated dermal thinning.

The neurobiological mechanisms and therapeutic prospect of extracellular ATP in depression.

Depression is a prevalent psychiatric disorder with high long-term morbidities, recurrences, and mortalities. Despite extensive research efforts spanning decades, the cellular and molecular mechanisms of depression remain largely unknown. What's more, about one third of patients do not have effective anti-depressant therapies, so there is an urgent need to uncover more mechanisms to guide the development of novel therapeutic strategies. Adenosine triphosphate (ATP) plays an important role in maintaining ion gradients essential for neuronal activities, as well as in the transport and release of neurotransmitters. Additionally, ATP could also participate in signaling pathways following the activation of postsynaptic receptors. By searching the website PubMed for articles about "ATP and depression" especially focusing on the role of extracellular ATP (eATP) in depression in the last 5 years, we found that numerous studies have implied that the insufficient ATP release from astrocytes could lead to depression and exogenous supply of eATP or endogenously stimulating the release of ATP from astrocytes could alleviate depression, highlighting the potential therapeutic role of eATP in alleviating depression. Currently, there are few reviews discussing the relationship between eATP and depression. Therefore, the aim of our review is to conclude the role of eATP in depression, especially focusing on the evidence and mechanisms of eATP in alleviating depression. We will provide insights into the prospects of leveraging eATP as a novel avenue for the treatment of depression.

Abstract PD15-08: The role of purinergic signaling in the chemotherapy response of triple negative breast cancer

Abstract Triple negative breast cancer (TNBC) affects women worldwide with a higher incidence in minority populations. Patients with TNBCs often have poorer prognoses in comparison to other breast cancer sub-types due to a lack of effective therapeutic options. Chemotherapy and immunotherapy are the only effective treatments, but these modalities generally result in short-term response. Therefore, there is a need to identify additional therapies to intensify the chemotherapeutic response in TNBC. When cancer cells are exposed to chemotherapy, they release adenosine triphosphate (ATP) into the extracellular space. Extracellular ATP is degraded by CD39 (E-NTPDase) to adenosine diphosphate (ADP) and then adenosine monophosphate (AMP), and AMP is broken down to adenosine by CD73. We examined the potential role of extracellular ATP in chemotherapy- induced cancer cell death. We hypothesized that extracellular ATP sensitizes TNBC cells to chemotherapy and that ATP degrading enzymes such as CD39 and CD73 attenuate this effect. TNBC MDA-MB 231, MDA-MB 468, and Hs 578t cell lines were treated with the chemotherapeutic agent paclitaxel for different time courses. Extracellular ATP was measured via the ATPlite 1step luminescence assay, and cell viability was assessed by applying PrestoBlue HS cell viability reagent. Paclitaxel-treated TNBC cell lines revealed a dose-dependent increase in extracellular ATP release in the presence of an inhibitor of CD39 (POM-1), accompanied by a dose-dependent decrease in cell viability. In addition, the general P2X receptor (P2RX) inhibitor iso-PPADS and the P2RX7 specific inhibitor (A438079) were added separately to observe if the P2X receptors are necessary for the release of ATP upon paclitaxel treatment. After paclitaxel treatment, TNBC cell lines showed a decline in the amount of ATP released with the addition of the inhibitors iso-PPADS and A438079. Treatment of non-tumorigenic immortalized MCF-10A mammary epithelial cells with paclitaxel in the presence and absence of the inhibitors iso-PPADS and A438079 did not result in a significant increase in extracellular ATP or a decrease in cell viability. These results indicate that P2RX7 is necessary for ATP release in TNBC cell lines exposed to chemotherapy. Furthermore, when TNBC cell lines were treated with increasing concentrations of ATP, there was a dose-dependent decrease in cell viability. Overall, these findings suggest that extracellular ATP may impact the chemotherapeutic response in TNBC cell lines through the activation of the ATP-gated channel P2RX7. Citation Format: Jasmine Manouchehri, Jharna Datta, Mathew Cherian. The role of purinergic signaling in the chemotherapy response of triple negative breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD15-08.

Complementary Role of P2 and Adenosine Receptors in ATP Induced-Anti-Apoptotic Effects Against Hypoxic Injury of HUVECs.

Background: Vascular endothelial injury during ischemia generates apoptotic cell death and precedes apoptosis of underlying tissues. We aimed at studying the role of extracellular adenosine triphosphate (ATP) on endothelial cells protection against hypoxia injury. Methods: In a hypoxic model on endothelial cells, we quantified the extracellular concentration of ATP and adenosine. The expression of mRNA (ectonucleotidases, adenosine, and P2 receptors) was measured. Apoptosis was evaluated by the expression of cleaved caspase 3. The involvement of P2 and adenosine receptors and signaling pathways was investigated using selective inhibitors. Results: Hypoxic stress induced a significant increase in extracellular ATP and adenosine. After a 2-h hypoxic injury, an increase of cleaved caspase 3 was observed. ATP anti-apoptotic effect was prevented by suramin, pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS), and CGS15943, as well as by selective A2A, A2B, and A3 receptor antagonists. P2 receptor-mediated anti-apoptotic effect of ATP involved phosphoinositide 3-kinase (PI3K), extracellular signal-regulated kinases (ERK1/2), mitoKATP, and nitric oxide synthase (NOS) pathways whereas adenosine receptor-mediated anti-apoptotic effect involved ERK1/2, protein kinase A (PKA), and NOS. Conclusions: These results suggest a complementary role of P2 and adenosine receptors in ATP-induced protective effects against hypoxia injury of endothelial. This could be considered therapeutic targets to limit the development of ischemic injury of organs such as heart, brain, and kidney.

The Role of Extracellular Adenosine Triphosphate in Ischemic Organ Injury.

Ischemic tissue injury contributes to significant morbidity and mortality and is implicated in a range of pathologic conditions, including but not limited to myocardial infarction, ischemic stroke, and acute kidney injury. The associated reperfusion phase is responsible for the activation of the innate and adaptive immune system, further accentuating inflammation. Adenosine triphosphate molecule has been implicated in various ischemic conditions, including stroke and myocardial infarction. Adenosine triphosphate is a well-defined intracellular energy transfer and is commonly referred to as the body's "energy currency." However, Laboratory studies have demonstrated that extracellular adenosine triphosphate has the ability to initiate inflammation and is therefore referred to as a damage-associated molecular pattern. Purinergic receptors-dependent signaling, proinflammatory cytokine release, increased Ca influx into cells, and subsequent apoptosis have been shown to form a common underlying extracellular adenosine triphosphate molecular mechanism in ischemic organ injury. In this review, we aim to discuss the molecular mechanisms behind adenosine triphosphate-mediated ischemic tissue injury and evaluate the role of extracellular adenosine triphosphate in ischemic injury in specific organs, in order to provide a greater understanding of the pathophysiology of this complex process. We also appraise potential future therapeutic strategies to limit damage in various organs, including the heart, brain, kidneys, and lungs.

Extracellular ATP Is a Danger Signal Activating P2X7 Receptor in Lung Inflammation and Fibrosis

Pulmonary fibrosis is a devastating as yet untreatable disease. We previously investigated the endogenous mediators released on lung injury and showed that uric acid is a danger signal activating Nod-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome in lung inflammation and fibrosis (Gasse et al., Am J Respir Crit Care Med 2009;179:903-913). Here we address the role of extracellular adenosine triphosphate (eATP) in pulmonary inflammation and fibrosis. ATP was quantified in bronchoalveolar lavage fluid (BALF) of control subjects and patients with idiopathic pulmonary fibrosis. The contribution of eATP as a danger signal was assessed in a murine model of lung fibrosis induced by airway-administered bleomycin (BLM), an intercalating agent that causes DNA strand breaks. Fibrotic patients have elevated ATP content in BALF in comparison with control individuals. In mice, we report an early increase in eATP levels in BALF on BLM administration. Modulation of eATP levels with the ATP-degrading enzyme apyrase greatly reduced BLM-induced inflammatory cell recruitment, lung IL-1β, and tissue inhibitor of metalloproteinase (TIMP)-1 production, while administration of ATP-γS, a stable ATP derivative, enhanced inflammation. P2X(7) receptor-deficient mice presented dramatically reduced lung inflammation, with reduced fibrosis markers such as lung collagen content and matrix-remodeling proteins TIMP-1 and matrix metalloproteinase-9. The acute inflammation depends on a functional pannexin-1 hemichannel protein. In vitro, ATP is released by pulmonary epithelial cells on BLM-induced stress and this is partly dependent on the presence of functional P2X(7) receptor and pannexin-1 hemichannel. ATP released from BLM-injured lung cells constitutes a major endogenous danger signal that engages the P2X(7) receptor/pannexin-1 axis, leading to IL-1β maturation and lung fibrosis.

Limiting the Damage

Toll-like receptors (TLR), found in cells of the innate immune system, recognize conserved microbial patterns to mediate proinflammatory responses and thereby eliminate pathogens. When out of control, however, these responses can be dangerous to the host; indeed, activation of TLR4 by lipopolysaccharide (LPS, found in Gram-negative bacterial membranes) can lead to life-threatening endotoxic shock. Tissue damage can lead to the release of adenosine triphosphate (ATP); thus, Kaufmann et al . investigated the possible role of extracellular ATP as a "damage signal" that modulates TLR signaling. The authors used reverse transcription polymerase chain reaction (RT-PCR) to show that human peripheral blood monocytes expressed various P2Y and P2X purinergic receptors. Exposure to ATP increased monocyte adenosine 3′,5′-monophosphate (cAMP) content, elicited a biphasic intracellular calcium signal, stimulated pseudopodial retraction, and promoted nondirectional cell migration. LPS stimulated the production of tumor necrosis factor α (TNFα); ATPγS inhibited LPS-stimulated secretion of TNFα and monocyte chemoattractant protein-1 (MCP-1), whereas it enhanced LPS-stimulated secretion of the anti-inflammatory interleukin-10 (IL-10). Pharmacological analysis indicated that this likely involved stimulation of the cAMP signaling pathway, mediated through P2Y 11 . Similarly, ATPγS inhibited the production of TNFα and MCP-1, and enhanced that of IL-10, elicited by stimulating TLR2 or the TLR2/6 complex with the appropriate ligands. Thus, the authors suggest that ATP released from injured cells acts through P2Y 11 and the cAMP pathway to limit the proinflammatory response to TLR activation. A. Kaufmann, B. Musset, S. H. Limberg, V. Renigunta, R. Sus, A. H. Dalpke, K. M. Heeg, B. Robaye, P. J. Hanley, "Host tissue damage" signal ATP promotes non-directional migration and negatively regulates Toll-like receptor signaling in human monocytes. J. Biol. Chem. 280 , 32459-32467 (2005). [Abstract] [Full Text]

Role of extracellular adenosine triphosphate in human skin.

The nucleotide adenosine triphosphate (ATP) has long been known to drive and participate in countless intracellular processes. Extracellular ATP and its metabolite adenosine have also been shown to exert a variety of effects on nearly every cell type in human skin. Knowledge of the sources and effects of extracellular ATP in human skin may help shape new therapies for skin injury, inflammation, and numerous other cutaneous disorders. The objective of this review is to introduce the reader to current knowledge regarding the sources and effects of extracellular ATP in human skin and to outline areas in which further research is necessary to clarify the nature and mechanism of these effects. Extracellular ATP seems to play a direct role in triggering skin inflammatory, regenerative, and fibrotic responses to mechanical injury, an indirect role in melanocyte proliferation and apoptosis, and a complex role in Langerhans cell-directed adaptive immunity.

Role of Extracellular Adenosine Triphosphate in Human Skin

Background:The nucleotide adenosine triphosphate (ATP) has long been known to drive and participate in countless intracellular processes. Extracellular ATP and its metabolite adenosine have also been shown to exert a variety of effects on nearly every cell type in human skin. Knowledge of the sources and effects of extracellular ATP in human skin may help shape new therapies for skin injury, inflammation, and numerous other cutaneous disorders.Objective:The objective of this review is to introduce the reader to current knowledge regarding the sources and effects of extracellular ATP in human skin and to outline areas in which further research is necessary to clarify the nature and mechanism of these effects.Conclusion:Extracellular ATP seems to play a direct role in triggering skin inflammatory, regenerative, and fibrotic responses to mechanical injury, an indirect role in melanocyte proliferation and apoptosis, and a complex role in Langerhans cell-directed adaptive immunity.

Role of Extracellular Adenosine Triphosphate in the Cytotoxic T-Lymphocyte-Mediated Lysis of Antigen Presenting Cells

The lysis of antigen presenting cells (APCs) by cytotoxic T lymphocytes (CTLs) may be one mechanism whereby an immune response is downregulated by Staphylococcus superantigens. Disappearance of monocytes/macrophages from staphylococcal enterotoxin A (SEA)-activated peripheral blood mononuclear cell (PBMC) cultures, but not from control PBMC cultures was seen by flow cytometry. Recently, adenosine triphosphate (ATP) has been described as an effector molecule in CTL-mediated lysis of some murine tumor target cells. We have also shown that ATP caused the lysis of human macrophages, and that treatment of cells with interferon gamma (IFN gamma) rendered macrophages significantly more sensitive to ATP than untreated cells. To show that this purine nucleotide may play a role in modulating the immune system, we generated human CTLs that were stimulated with SEA, and used them as effector cells against SEA-pulsed autologous macrophages. CTLs were found to specifically lyse SEA-pulsed macrophages, while control, unpulsed, macrophages were unaffected. The addition of hexokinase, an enzyme that hydrolyzes ATP, significantly abrogated the killing of SEA-pulsed cells during the assay. In examining the mechanism of cytotoxicity, electron microscopy showed that macrophages incubated with both ATP and CTLs underwent necrosis, rather than apoptosis. From these results, it is suggested that ATP is released from CTLs during antigen presentation, and that IFN gamma-activated macrophages, which are inherently more sensitive to this mediator, are readily lysed and therefore removed from circulation, thus downregulating an immune response.

Modulation of Platelet Function by Extracellular Adenosine Triphosphate

A potential physiologic role of extracellular adenosine triphosphate (ATP) on platelet function is proposed in this report. It is widely accepted that ATP competitively inhibits adenosine diphosphate (ADP)-induced platelet aggregation. Our observations of platelet aggregation with the agonists, collagen, epinephrine, and ADP in the presence of 180 mumol/L ATP could support this competitive nature of ATP. However, the disaggregation of maximally aggregated platelets induced by ATP, theophylline, or ATP plus theophylline indicates that additional mechanisms of ATP action may be present. Extracellular gamma-32P-ATP (7 pmol) labels surface-membrane proteins in intact platelets as demonstrated by several criteria. The reaction is Ca++-dependent. Stimulation by calcium occurs in the physiologic range of 1 to 5 mmol/L. Significant levels of phosphorylation occur within one minute with near maximal levels reached by five minutes. Platelet cyclic AMP (cAMP) levels were elevated in a dose-dependent fashion in cells incubated for four minutes with increasing amounts of extracellular ATP (18 to 540 nmol). The addition of ATP plus theophylline resulted in a synergistic stimulation of cAMP levels. ATP was not being hydrolyzed to adenosine by plasma nucleotidases, as demonstrated by the lack of effect of ten U of adenosine deaminase. The phosphorylation of surface proteins by extracellular ATP released from activated platelets may modulate platelet responsiveness to agonists at distances removed from the site of vascular injury. Phosphorylation may also play a role in signal transduction to regulate the levels of intracellular cAMP, which further inhibits platelet activation.

Modulation of platelet function by extracellular adenosine triphosphate

A potential physiologic role of extracellular adenosine triphosphate (ATP) on platelet function is proposed in this report. It is widely accepted that ATP competitively inhibits adenosine diphosphate (ADP)- induced platelet aggregation. Our observations of platelet aggregation with the agonists, collagen, epinephrine, and ADP in the presence of 180 mumol/L ATP could support this competitive nature of ATP. However, the disaggregation of maximally aggregated platelets induced by ATP, theophylline, or ATP plus theophylline indicates that additional mechanisms of ATP action may be present. Extracellular gamma-32P-ATP (7 pmol) labels surface-membrane proteins in intact platelets as demonstrated by several criteria. The reaction is Ca++-dependent. Stimulation by calcium occurs in the physiologic range of 1 to 5 mmol/L. Significant levels of phosphorylation occur within one minute with near maximal levels reached by five minutes. Platelet cyclic AMP (cAMP) levels were elevated in a dose-dependent fashion in cells incubated for four minutes with increasing amounts of extracellular ATP (18 to 540 nmol). The addition of ATP plus theophylline resulted in a synergistic stimulation of cAMP levels. ATP was not being hydrolyzed to adenosine by plasma nucleotidases, as demonstrated by the lack of effect of ten U of adenosine deaminase. The phosphorylation of surface proteins by extracellular ATP released from activated platelets may modulate platelet responsiveness to agonists at distances removed from the site of vascular injury. Phosphorylation may also play a role in signal transduction to regulate the levels of intracellular cAMP, which further inhibits platelet activation.