Role of macrophage TRPV4 in inflammation.

Transient receptor ion channels have emerged as immensely important channels/receptors in diverse physiological and pathological responses. Of particular interest is the transient receptor potential channel subfamily V member 4 (TRPV4), which is a polymodal, nonselective, calcium-permeant cation channel, and is activated by both endogenous and exogenous stimuli. Both neuronal and nonneuronal cells express functional TRPV4, which is responsive to a variety of biochemical and biomechanical stimuli. Emerging discoveries have advanced our understanding of the role of macrophage TRPV4 in numerous inflammatory diseases. In lung injury, TRPV4 mediates macrophage phagocytosis, secretion of pro-resolution cytokines, and generation of reactive oxygen species. TRPV4 regulates lipid-laden macrophage foam cell formation, the hallmark of atheroinflammatory conditions, in response to matrix stiffness and lipopolysaccharide stimulation. Accumulating data also point to a role of macrophage TRPV4 in the pathogenesis of the foreign body response, a chronic inflammatory condition, through the formation of foreign body giant cells. Deletion of TRPV4 in macrophages suppresses the allergic and nonallergic itch in a mouse model, suggesting a role of TRPV4 in skin disease. Here, we discuss the current understanding of the role of macrophage TRPV4 in various inflammatory conditions.