Pharmacological inhibition of TRPV2 attenuates phagocytosis and lipopolysaccharide-induced migration of primary macrophages

Background and purpose: In macrophages, transient receptor potential vanilloid 2 (TRPV2) channel contributes to various cellular processes such as cytokine production, differentiation, phagocytosis and migration. Due to a lack of selective pharmacological tools, its function in immunological processes is not well understood and the identification of novel and selective TRPV2 modulators is highly desirable.

Experimental approach: Novel and selective TRPV2 modulators were identified by screening a compound library using Ca²⁺ influx assays with human embryonic kidney 293 (HEK293) cells heterologously expressing rat TRPV2. Hits were further characterized and validated with Ca²⁺ influx and electrophysiological assays. Phagocytosis and migration of macrophages were analysed and the contribution of TRPV2 to the generation of Ca²⁺ microdomains was studied by total internal reflection fluorescence microscopy (TIRFM).

Key results: The compound IV2-1, a dithiolane derivative (1,3-dithiolan-2-ylidene)-4-methyl-5-phenylpentan-2-one), is a potent inhibitor of heterologously expressed TRPV2 channels (IC₅₀ = 6.3 ± 0.7 μM) but does not modify TRPV1, TRPV3 or TRPV4 channels. IV2-1 also inhibits TRPV2-mediated Ca²⁺ influx in macrophages. IV2-1 inhibits macrophage phagocytosis along with valdecoxib and after siRNA-mediated knockdown. Moreover, TRPV2 inhibition inhibits lipopolysaccharide-induced migration of macrophages whereas TRPV2 activation promotes migration. After activation, TRPV2 shapes Ca²⁺ microdomains predominantly at the margin of macrophages, which are important cellular regions to promote phagocytosis and migration.

Conclusions and implications: IV2-1 is a novel TRPV2-selective blocker and underline the role of TRPV2 in macrophage-mediated phagocytosis and migration. Furthermore, we provide evidence that TRPV2 activation generates Ca²⁺ microdomains, which may be involved in phagocytosis and migration of macrophages.

Ca2+ microdomains; LPS-induced migration; TRPV2; macrophages; phagocytosis; small-molecule blocker; transient receptor potential vanilloid.