Expression and functional characterization of protease-activated receptor 2 (PAR2) and PAR1 on human skin mast cells

Abstract

Abstract Mast cells play an important role in the pathophysiology of asthma and allergic disease by releasing proinflammatory mediators and cytokines. Activation of protease-activated receptors (PARs) may also play a role in inflammatory response. We investigated the expression of PAR1, 2, 3 and 4 as well as the function of PAR1 and 2 in cultured human skin-derived mast cells (SMCs). Using a combination of flow cytometric analysis, reverse transcriptase-polymerase chain reaction and Western blotting, we demonstrate that human SMCs express PAR1, 2, 3 and 4. Confocal microscopy indicates PAR2 partially colocalize with tryptase within SMCs. Exposure to PAR2 agonist, trypsin and activating peptide (AP) 2-Furoyl-LIGRLO-NH2 induce Ca2+ mobilization in SMCs. The PAR1 APs, SFLLRN-NH2 and TFLLR-NH2 cause degranulation and induce GM-CSF and IL-8 synthesis. Similarly, the PAR2 APs, SLIGKV-NH2, 2-Furoyl-LIGRLO-NH2 also cause degranulation and induce GM-CSF and IL-8 synthesis in SMCs. Both PAR1 APs and PAR2 APs induce rapid phosphorylation of ERK and pertussis toxin (PTX) robustly inhibits phosphorylation of ERK by both PAR1 APs and PAR2 APs. These studies indicate that human SMCs can be activated by both PAR1 and PAR2 which may contribute to MC-mediated inflammatory process.