Fig. 2.

Schematic representation of P2 receptor signaling in COVID-19 inflammation. During SARS-CoV-2 infection, ATP is released from damaged or infected cells via Pannexin-1 channels. Extracellular ATP activates P2X7 on macrophages and dendritic cells, promoting the secretion of pro-inflammatory cytokines such as IL-1β, IL-6, and IL-18. Concurrently, ATP is enzymatically converted to adenosine via CD39 and CD73. Adenosine binds to A2B receptors, further enhancing IL-6 production in inflamed tissues. This dual purinergic axis contributes to the cytokine storm and pulmonary dysfunction observed in severe COVID-19