Major Role for TRPV1 and InsP3R in PAR2-Elicited Inflammatory Mediator Production in Differentiated Human Keratinocytes

Abstract

PAR2 activation in basal keratinocytes stimulates inflammation via the Ca²⁺-dependent production of mediators such as IL-1β, TNF-α, and TSLP. In this study, we investigated PAR2 calcium signaling and the consequent production of inflammatory mediators in differentiated human primary keratinocytes (DhPKs). Stimulation with the PAR2-activating peptide SLIGKV promoted Ca²⁺ store depletion in both undifferentiated human primary keratinocytes and DhPKs. SLIGKV-evoked Ca²⁺ store depletion did not trigger the store-operated Ca²⁺ entry (i.e., SOCE) through ORAI1 in DhPKs compared with undifferentiated human primary keratinocytes. The inhibition of phospholipase C and the concomitant inhibition of TRPV1 and inositol triphosphate receptor in DhPKs abrogated the SLIGKV-evoked Ca²⁺ store depletion; NF-κB activity; and the production of inflammatory mediators such as IL-1β, TNF-α, and TSLP. Taken together, these results indicate a key role for both InsP3R and TRPV1 in Ca²⁺ internal stores in the PAR2-evoked Ca²⁺ release and consequent skin inflammation in DhPKs. These findings may provide clues to understanding the pathological role of DhPKs in skin disorders in which PAR2 is known to be involved, such as atopic dermatitis, Netherton syndrome, and psoriasis.