Differential effect of Androctonus australis hector venom components on macrophage KV channels: electrophysiological characterization

Abstract

Neurotoxins of scorpion venoms modulate ion channels. Voltage-gated potassium (K) 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 K 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 K current between resting and LPS-activated macrophages. Aah venom significantly reduced K 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 K current in LPS-activated macrophages. Unlike cloned K1.5 channels, Aah venom exerted a similar blocking effect on K1.3 compared to K current in LPS-activated macrophages, along with a hyperpolarizing shift in the voltage dependence of K1.3 inactivation, indicating a direct mechanism of current inhibition by targeting K1.3 subunits. The obtained results, demonstrating that Aah venom differentially targets K channels in macrophages, suggest differential outcomes for their inhibitions, and that further investigations of scorpion venom immunomodulatory potential are required.

KV1.3 channels are novel determinants of macrophage‐dependent endothelial dysfunction in angiotensin II‐induced hypertension in mice

“…Intraperitoneal macrophages from control, AngII, AngII + [EWSS]ShK, and AngII + HsTX[R14A] mice were obtained in PBS (Khemili et al, 2019; Zhang et al, 2008) and cultured in DMEM, supplemented with 10% FBS, 100 IU·ml −1 penicillin, 100 μg·ml −1 streptomycin, and 10 mmol·L −1 l ‐glutamine, for 24 h. Macrophage‐conditioned media were collected and stored at −80°C. The mRNA and protein from macrophages were obtained and quantified.…”

Immunological Responses to Envenomation

“…Contrasting this research, Khemili et al examined the immunosuppressive potential of ion channel modulators from scorpion venom using murine MΦs ( 54 ). Voltage-gated potassium channels (K V ) play a crucial role in calcium signalling and immune cell excitability ( 54 ). In the resting state, murine MΦs predominantly express the K V 1.5 subunit of the K V 1.5/K V 1.3 heterotetrameric complex ( 54 ).…”

“…Voltage-gated potassium channels (K V ) play a crucial role in calcium signalling and immune cell excitability ( 54 ). In the resting state, murine MΦs predominantly express the K V 1.5 subunit of the K V 1.5/K V 1.3 heterotetrameric complex ( 54 ). Innate activation, including LPS stimulation, induces K V 1.3 overexpression ( 54 ).…”

“…In the resting state, murine MΦs predominantly express the K V 1.5 subunit of the K V 1.5/K V 1.3 heterotetrameric complex ( 54 ). Innate activation, including LPS stimulation, induces K V 1.3 overexpression ( 54 ). Using non-cytotoxic concentrations of Androctonus australis hector (Aah) venom, the authors observed a voltage-independent inhibition of K V current amplitude in LPS-activated (M1) MΦs ( 54 ).…”

“…Innate activation, including LPS stimulation, induces K V 1.3 overexpression ( 54 ). Using non-cytotoxic concentrations of Androctonus australis hector (Aah) venom, the authors observed a voltage-independent inhibition of K V current amplitude in LPS-activated (M1) MΦs ( 54 ). On the contrary, venom perfusion did not significantly decrease K V current amplitude in resting cells ( 54 ).…”