Ethanol differentially modulates P2X4 and P2X7 receptor activity and function in BV2 microglial cells

Abstract

Neuroinflammation is one of the mechanisms leading to neurodegenerative brain damage induced by chronic alcohol (ethanol) exposure. Microglia play a major role in the development of innate immune responses to environmental injuries including ethanol. Adenosine 5″-triphosphate (ATP)-activated purinergic P2X receptor (P2XR) subtypes, P2X4Rs and P2X7Rs, are endogenously expressed in microglia and can modulate their activity. These 2 P2XR subtypes differ pharmacologically and functionally: 1) P2X4Rs are activated at lower (≤0.1 mM) whereas P2X7Rs - at higher (≥1.0 mM) ATP concentrations; 2) P2X4R activation contributes to the release of brain derived neurotrophic factor and its role in tactile allodynia and neuropathic pain is demonstrated; 3) Due to its role in the secretion of pro-inflammatory IL-1β, P2X7Rs have been implicated in the development of neurodegenerative pathologies, pain and morphine tolerance. To date, the roles of individual P2XR subtypes in ethanol effects on microglia and the functional consequences are not completely understood. Based on the existing knowledge on the pharmacological and functional differences between P2X4Rs and P2X7Rs, the present work tested the hypothesis that P2X4Rs and P2X7Rs play differential roles in ethanol action in microglia. Effects of ethanol on P2X4R and P2X7R activity, expression and functional consequences were determined using murine BV2 microglial cells. Ethanol (≥100 mM) inhibited P2X4Rs but was inactive on P2X7 channel activity. Ethanol (25, 100 mM) inhibited P2X4R-mediated microglia migration whereas it potentiated pore formation in P2X7Rs. Furthermore, ethanol (25, 100 mM) potentiated P2X7R-mediated IL-1β secretion from BV2 microglia. Ethanol also induced protein expression for both P2XR subtypes. Overall, the findings identify differential roles for P2X4Rs and P2X7Rs in regards to ethanol effects on microglia which may be linked to different stages of ethanol exposure.

Metabolic regulation of inflammasomes in inflammation

“…It is known that TLR4 signalling only partially regulates cytokine production, and increased active HMGB1 is assumed to play a crucial role in triggering NLRP3 inflammasome activation . For microglial cells, alcohol augments the activation of P2X7R, which is an ATP‐gated cation channel often involved in ATP‐triggered NLRP3 inflammasome activation . Neuroinflammation in mice fed a mix of ethanol and a high‐fat diet (HFD) is inhibited by treatment with P2X7R antagonist .…”

“…134 For microglial cells, alcohol augments the activation of P2X7R, which is an ATP-gated cation channel often involved in ATP-triggered NLRP3 inflammasome activation. 135,136 Neuroinflammation in mice fed a mix of ethanol and a high-fat diet (HFD) is inhibited by treatment with P2X7R antagonist. 137 Further studies about diet and its correlation with sterile inflammation may focus on its mechanism of mediating the activation of the inflammasome to formulate specific diet regulations.…”

P2X7 receptor in cardiovascular disease: The heart side

“…Primary human monocyte‐derived macrophages stimulated monosodium urate (MSU) or ethanol up‐regulate P2X7 mRNA and protein levels . Ethanol can also induce this effect in murine microglial cells . Moreover, pro‐inflammatory molecules such as interferon‐γ (IFN‐γ), tumour necrosis factor α (TNFα) and lipopolysaccharide (LPS) can up‐regulate P2X7 expression and function in monocytes and macrophages .…”

“…54,55 Ethanol can also induce this effect in murine microglial cells. 56 Moreover, pro-inflammatory molecules such as interferon-γ (IFN-γ), tumour necrosis factor α (TNFα) and lipopolysaccharide (LPS) can up-regulate P2X7 expression and function in monocytes and macrophages. 52,57 The effects of pro-inflammatory cytokines on P2X7 are not restricted to immune cells, as IFN-γ can also up-regulate P2X7 expression and function in epithelial cells, such as primary human epithelial cells from intestine and HeLa cells, cells originated from the uterine cervical epithelium.…”

Ethanol in Food affects behaviour and HPA axis activity during development in zebrafish larvae Subhead: Ethanol in Food affects Nerves during development in zebrafish larvae

“…Ethanol is a substance consume daily by humans that can cause considerable harm to human health (especially by minors) [1]. Indeed, the social and health effects of alcoholism are one of the most serious problems faced by governments and families every year [2]. Recent studies have found that long-term consumption of ethanol can lead to numerous physical [2], behavioural [3], and mental disorders [4].Alcohol consumption is a leading contributor to death from injuries, which itself is one of the main causes of death.…”