P2Y6 signaling selectively regulates TLR3-induced chemokine release in murine bone marrow-derived macrophages, with opposing effects on CCL2 and CXCL1

Extracellular nucleotides regulate diverse inflammatory responses through the activation of P2 receptors. Here, we show that nucleotides regulate TLR3-induced chemokine responses in murine bone marrow-derived macrophages (BMDMs). Stimulation with the TLR3 agonist, poly(I:C), induced CCL2 and CXCL1 secretion, whereas degradation of extracellular nucleotides with apyrase reduced CCL2 but enhanced CXCL1 release. In agreement, the non-selective P2 receptor antagonists suramin and RB2 reduced poly(I:C)-induced CCL2 production. Among the highly expressed P2 receptors examined, selective inhibition of P2Y6 with MRS2578 reproduced the effects of apyrase, decreasing CCL2 while increasing CXCL1 secretion. The absence of effects of MRS2578 in P2ry6-deficient BMDMs confirmed the specificity of this antagonist. Transcriptional analysis further revealed that P2Y6 inhibition reduced early poly(I:C)-induced Ccl2 and Cxcl10 expression while enhancing later Cxcl1 and Cxcl2 expression. In line with our previous works on other pattern-recognition receptors pathways and innate immune cells, this study further supports a role for extracellular nucleotides in shaping TLR-induced chemokine responses in macrophages.