Anti-Inflammatory Role of TRPV4 in Human Macrophages

The pathology of skin immune diseases such as atopic dermatitis is closely related to the overproduction of cytokines by macrophages. Although the pathological functions of macrophages in skin are known, mechanisms of how they detect the tissue environment remain unknown. TRPV4, a nonselective cation channel with high Ca(2+) permeability, is activated at physiological temperatures from 27 to 35°C and involved in the functional control of macrophages. However, the relationship between TRPV4 function in macrophages and skin immune disease is unclear. In this study, we demonstrate that TRPV4 activation inhibits NF-κB signaling, resulting in the suppression of IL-1β production in both human primary monocytes and macrophages derived from human primary monocytes. A TRPV4 activator also inhibited the differentiation of human primary monocytes into GM-CSF M1 macrophages but not M-CSF M2 macrophages. We also observed a significant increase in the number of inducible NO synthase–positive/TRPV4-negative dermal macrophages in atopic dermatitis compared with healthy human skin specimens. Our findings provide insight into the physiological relevance of TRPV4 to the regulation of macrophages during homeostasis maintenance and raise the potential for TRPV4 to be an anti-inflammatory target.