P2X7 receptor activation increases caveolin-1 expression and macrophage lipid raft formation boosting CD39 activity.

Macrophages are tissue-resident immune cells crucial for the initiation and maintenance of immune responses. Purinergic signaling modulates macrophage activity and impacts cellular plasticity. The ATP-activated purinergic receptor P2X7 has pro-inflammatory properties, which contribute to macrophage activation. P2X7 receptor signaling is in turn modulated by ectonucleotidases such as CD39/E-NTPDase1, expressed in caveolae and lipid rafts. Here, we examined P2X7 receptor activity and determined impacts on ectonucleotidase localization and function in LPS-primed macrophages. First, we verified that ATP boosted CD39 activity and caveolin-1 expression in LPS-primed macrophages. Drugs that disrupt cholesterol-enriched domains - such as nystatin and methyl-β-cyclodextrin - decreased CD39 enzymatic activity in all circumstances. We noted that CD39 colocalized with lipid raft markers (flotillin-2 and caveolin-1) in LPS-primed macrophages treated with ATP. P2X7 receptor inhibition blocked these ATP-mediated increases in caveolin-1 expression and inhibited the colocalization with CD39. Further, we found that STAT3 activation is significantly attenuated in LPS and LPS+BzATP-treated caveolin-1 deficient macrophages. Taken together, our data suggest that P2X7 receptor triggers the initiation of lipid raft-dependent mechanisms that upregulates CD39 activity and could contribute to limit macrophage responses restoring homeostasis.