TRPV4 activation increases the expression of CD207 (Langerin) of monocyte-derived Langerhans cells, without affecting their maturation.

Langerhans cells (LCs) are the sole professional antigen-presenting cell normally found in the human epidermal compartment. Research into their physiological role is hindered by the fact that they are invariably activated during isolation from the skin. To overcome this challenge, we turned to a monocyte-derived LC model (moLC), which we characterized with RNASeq, and compared the transcriptome of moLCs to donor-matched immature dendritic cells. We found that moLCs express markers characteristic of LC2 cells, as well as transient receptor potential vanilloid 4 (TRPV4). TRPV4 is especially important in skin, as it has been linked to conservation of the skin barrier, immunological responses as well as acute and chronic itch, but we know little about its function on LCs. Our results show that TRPV4 activation increased the expression of Langerin and led to increased intracellular calcium concentration in moLCs. Regarding the functionality of moLCs, we found that TRPV4 agonism had a mitigating effect on their inflammatory responses, since it decreased their cytokine production, and T cell activating capability. As TRPV4 has emerged as a potential therapeutic target in dermatological conditions, it is important to highlight LCs as a novel target of these therapies.