A KCa 2.2/2.3 opener reverses ET-1 induced NLRP3 activation in hypertensive mice

Abstract

Hypertension-induced erectile dysfunction is associated with endothelial dysfunction in the corpus cavernosum. Membrane depolarization activates the NLRP3 inflammasome, with downregulation of endothelial Ca2+-activated K+ channels type 2.3 (KCa 2.3) and upregulation of endothelin-1 (ET-1) linked to erectile dysfunction. However, underlying mechanisms remain incompletely understood. We hypothesized that activating KCa 2.2/2.3 channels reverses erectile dysfunction and ET-1-induced NLRP3 activation in hypertensive DOCA/salt mice. Hypertension was induced in mice using a DOCA/salt model, with unilaterally nephrectomized mice as controls. We measured blood pressure, intracavernous pressure (ICP), and corpus cavernosum (CC) contractility, and performed immunoblots for KCa 2.3, caspase-1, and interleukin-1{beta} (IL-1{beta}). DOCA/salt mice showed impaired erectile function and increased IL-1{beta} activity and KCa 2.3 expression. Treatment with the endothelin receptor antagonist bosentan or the KCa 2.2/2.3 channel opener NS13001 reversed these dysfunctions and reduced ET-1-induced NLRP3 activation. NS13001 also restored decreased currents in endothelial cells exposed to ET-1. These findings establish that hypertension-induced erectile dysfunction involves an ET-1/membrane depolarization/NLRP3 inflammasome axis in corpus cavernosum endothelial cells, and that targeting endothelial KCa2.2/2.3 channels represents a promising therapeutic strategy to counteract erectile dysfunction. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/611748v2_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@c4ed5org.highwire.dtl.DTLVardef@b915corg.highwire.dtl.DTLVardef@1744cc9org.highwire.dtl.DTLVardef@5d47d9_HPS_FORMAT_FIGEXP M_FIG Graphic abstract Overview of the KCa2.2/2.3 regulation on the ET-1-induced NLRP3 inflammasome activation in ECs. NLRP3 inflammasome activation in ECs depends on endothelin receptor B. On activation, NLRP3 recruits and forms a complex with ASC as well as procaspase 1. In the final step, the assembled inflammasome platform cleaves pro-caspase-1, and caspase-1 cleaves pro-IL-1 to activate IL-1. NS13001 activates KCa2.2/2.3, which inhibits ET-1-induced NLRP3 activation. Apamin inhibits KCa2.2/2.3 opening. Bosentan directly inhibits ETB receptors in ECs, preventing the NLRP3 inflammasome activation. C_FIG