Purinergic receptor P2X7 regulates interleukin-1α mediated inflammation in chronic kidney disease in a reactive...

Onset, progression and cardiovascular outcome of chronic kidney disease (CKD) are influenced by the concomitant sterile inflammation. The pro-inflammatory cytokine family interleukin (IL)-1 is crucial in CKD with the key alarmin IL-1α playing an additional role as an adhesion molecule that facilitates immune cell tissue infiltration and consequently inflammation. Here, we investigate calcium ion and reactive oxygen species (ROS)-dependent regulation of different aspects of IL-1α-mediated inflammation. We show that human CKD monocytes exhibit altered purinergic calcium ion signatures. Monocyte IL-1α release was reduced when inhibiting P2X7, and to a lesser extent P2X4, two ATP-receptors that were found upregulated compared to monocytes from healthy people. In murine CKD models, deleting P2X7 (P2X7^-/-) abolished IL-1α release but increased IL-1α surface presentation by bone marrow derived macrophages and impaired immune cell infiltration of the kidney without protecting kidney function. In contrast, immune cell infiltration into injured wild type and P2X7^-/- hearts was comparable in a myocardial infarction model, independent of previous kidney injury. Both the chimeric mouse line harboring P2X7^-/- immune cells in wild type recipient mice, and the inversely designed chimeric line showed less acute inflammation. However, only the chimera harboring P2X7^-/- immune cells showed a striking resistance against injury-induced cardiac remodeling. Mechanistically, ROS measurements reveal P2X7-induced mitochondrial ROS as an essential factor for IL-1α release by monocytes. Our studies uncover a dual role of P2X7 in regulating IL-1α biogenesis with consequences for inflammation and inflammation-induced deleterious cardiac remodeling that may determine clinical outcomes in CKD therapies.