Differential effect of Androctonus australis hector venom components on macrophage KV channels: electrophysiological characterization
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Neurotoxins of scorpion venoms modulate ion channels. Voltage-gated potassium (KV) channels regulate the membrane potential and are involved in the activation and proliferation of immune cells. Macrophages are key components of the inflammatory response induced by scorpion venom. The present study was undertaken to investigate the effect of Androctonus australis hector (Aah) venom on KV channels in murine resident peritoneal macrophages. The cytotoxicity of the venom was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) -based assay and electrophysiological recordings were performed using the whole-cell patch clamp technique. High doses of Aah venom (50, 125, 250 and 500 µg/ml) significantly decreased cell viability, while concentrations of 0.1–25 µg/ml were not cytotoxic towards peritoneal macrophages. Electrophysiological data revealed a differential block of KV current between resting and LPS-activated macrophages. Aah venom significantly reduced KV current amplitude by 62.5 ± 4.78% (n = 8, p < 0.05), reduced the use-dependent decay of the current, decreased the degree of inactivation and decelerated the inactivation process of KV current in LPS-activated macrophages. Unlike cloned KV1.5 channels, Aah venom exerted a similar blocking effect on KV1.3 compared to KV current in LPS-activated macrophages, along with a hyperpolarizing shift in the voltage dependence of KV1.3 inactivation, indicating a direct mechanism of current inhibition by targeting KV1.3 subunits. The obtained results, demonstrating that Aah venom differentially targets KV channels in macrophages, suggest differential outcomes for their inhibitions, and that further investigations of scorpion venom immunomodulatory potential are required.
KeywordsAah venom Modulation Macrophage Voltage-gated potassium channels KV1.3 KV1.5
The authors are grateful to Professor Ana Maria Briones (Departamento de Farmacología, Facultad de Medicina, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Universidad Autónoma de Madrid, Madrid, Spain) for providing help with murine peritoneal macrophage cultures and polarization. We are very grateful to Diego A. Peraza, Dr Alicia de la Cruz and Dr Teresa Gonzalez for technical and scientific assistance in patch-clamp experiments, cell transfection, isolation, culturing, polarization of murine peritoneal macrophages and data analysis.
Dalila Khemili received a scholarship from University of Sciences and Technology Hourari Boumediene, Algiers, Algeria. Ion channels laboratory (leaded by Dr. Carmen Valenzuela) received support from Ministerio de Economía, Industria y Competitividad (MINEICO) of Spain: SAF2013-45800-R, SAF2016-75021-R, CIBERCV CB/11/00222 and the European Regional Development Funds (FEDER).
CV, FLD and DHT designed the study; DK performed experiments, analyzed data and drafted the paper; DK and CV interpreted and discussed the electrophysiological data; CV, FLD and DHT wrote and corrected the article.
Compliance with ethical standards
Conflict of interest
The authors declare that there are no conflicts of interest.
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