A KCa2.2/2.3 opener reverses ET-1 induced NLRP3 activation in hypertensive mice
Authors: Fais RS , Comerma-Steffensen SG , Pinilla E , Matchkov VV , Tostes RC , Carneiro FS , Simonsen U 
Published: September 2024

Membrane depolarization is implicated in the activation of the NLRP3 inflammasome. Downregulation of endothelial Ca2+-activated K+ channels type 2.3 (KCa2.3) and endothelin-1 (ET-1) upregulation in the corpus cavernosum (CC) are associated with erectile dysfunction. We hypothesized that opening KCa2.2/2.3 channels could reverse erectile dysfunction and NLRP3 activation in hypertensive DOCA/salt mice. Methods: Hypertension was induced in mice using a DOCA/salt model, with unilaterally nephrectomized mice as controls; blood pressure was measured by tail-cuff. Intracavernous pressure (ICP) and CC reactivity were assessed. Western blot analysis for KCa2.3, caspase-1, and interleukin-1β (IL-1β) was performed. Endothelial cells from erectile tissue were isolated and stimulated with ET-1, and KCa2.2/2.3-dependent currents were evaluated via voltage-clamp electrophysiology. Results: DOCA/salt mice exhibited impaired erectile function, increased pro-caspase-1 and caspase-1 expression, and reduced relaxations induced by acetylcholine (ACh), sodium nitroprusside (SNP), and electrical field stimulation (EFS). Treatment with either the endothelin receptor antagonist bosentan or the KCa2.2/2.3 channel opener NS13001 reversed these dysfunctions and reduced ET-1-induced NLRP3 activation in DOCA/salt mice. NS13001 also restored the decreased current observed in primary endothelial cells exposed to ET-1. Apamin, a KCa2.2/2.3 channel blocker, inhibited erectile responses in unilaterally nephrectomized mice and restored erectile responses in DOCA mice. Apamin did not affect EFS-, ACh-, or SNP-induced relaxation in CC from hypertensive DOCA/salt mice. Conclusion: NS13001 reversed ET-1-induced NLRP3 activation and erectile dysfunction in DOCA/salt mice, suggesting that KCa2.2/2.3 channel modulation may restore erectile function in hypertension-related diseases.

Clinical Perspective

What Is New?

Our data indicate that the immune system, through the NLRP3 inflammasome, has a central role in endothelin-1- and hypertension-associated erectile dysfunction.

Endothelin-1 mediates the inflammasome activation through KCa2.3 inhibition in endothelial cells of erectile tissue

An opener of KCa2.3 channels, NS13001 counteracts endothelin-1-induced suppression of Ca2+-activated K+current in the endothelial cell membrane and development of erectile dysfunction in DOCA mice

What Are the Clinical Implications?

Endothelin-1 contributes to hypertension and erectile dysfunction by provoking an endothelial dysfunction through vascular inflammation,

NLRP3 inflammasome activation in endothelial cells is a key pathway behind endothelin-1-induced erectile dysfunction and is potentially involved in cardiovascular complications in patients with hypertension.

The KCa2.3 channel is a putative novel therapeutic target in erectile dysfunction, especially when the endothelin-1-NLRP3 inflammasome is involved.

Abstract Figure

Graphical Abstract 1.

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-1β to activate IL-1β. 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.