Mold Allergen, Pen c 13, Induces IL-8 Expression in Human Airway Epithelial Cells by Activating Protease-Activated Receptor 1 and 2

Abstract

Allergenic serine proteases are important in the pathogenesis of asthma. One of these, Pen c 13, is the immunodominant allergen produced by Penicillium citrinum. Many serine proteases induce cytokine expression, but whether Pen c 13 does so in human respiratory epithelial cells is not known. In this study, we investigated whether Pen c 13 caused IL-8 release and activated protease-activated receptors (PARs) in airway epithelial cells. In airway-derived A549 cells and normal human airway epithelial cells, Pen c 13 induced IL-8 release in a dose-dependent manner. Pen c 13 also increased IL-8 release in a time-dependent manner in A549 cells. Pen c 13 cleaved PAR-1 and PAR-2 at their activation sites. Treatment with Pen c 13 induced intracellular Ca2+ mobilization and desensitized the cells to the action of other proteases and PAR-1 and PAR-2 agonists. Moreover, Pen c 13-mediated IL-8 release was significantly decreased in Ca2+-free medium and was abolished by the protease inhibitors, PMSF and 4-(2-aminoethyl) benzenesulfonyl fluoride. Blocking Abs against the cleavage sites of PAR-1 and PAR-2, but not of PAR-4, inhibited Pen c 13-induced IL-8 production, as did inhibition of phospholipase C. Pen c 13 induced IL-8 expression via activation of ERK 1/2, and not of p38 and JNK. In addition, treatment of A549 cells or normal human airway epithelial cells with Pen c 13 increased phosphorylation of ERK 1/2 by a Ca2+-dependent pathway. These finding show that Pen c 13 induces IL-8 release in airway epithelial cells and that this is dependent on PAR-1 and PAR-2 activation and intracellular calcium.

TRPM2-mediated Ca2+ influx induces chemokine production in monocytes that aggravates inflammatory neutrophil infiltration

“…1a,b online). Consistent with previous reports 7,8,21,22 , CXCL8 production was suppressed by the Erk pathway inhibitor PD98059 and the NF-κB inhibitor PDTC (Fig. 1a,b and Supplementary Fig.…”

What makes an allergen?

“…The mite allergens, Der p 1 (cysteine protease) and Der p 3 (serine protease), were shown to induce IL-8 secretion from human alveolar EC A549, at which cytokine secretion by Der p 3 (and Der p 9, a serine protease) but not by Der p 1 depends on PAR-2 [56,59]. Proteolytic active mould allergen Pen c 13 (Penicillium citrinum), a serine protease, activates both PAR-1 and PAR-2 and induces IL-8 from human airway EC [60] (see PAR-1 and PAR-2 in Fig. 2).…”

Proteases in agricultural dust induce lung inflammation through PAR-1 and PAR-2 activation

“…Although fungal and bacterial cell wall components of agricultural dusts contribute to the inflammatory responses, these components do not entirely account for the inflammatory effects observed (27). Many common environmental irritants and aeroallergens, such as extracts from house dust mites, cockroaches, and numerous fungal species, have been reported to exhibit protease activity (2,23,30,31), which is implicated in bronchial inflammation, likely due in part to the release of inflammatory cytokines from BECs (5,8). Although proteases can exert their effects on cell function in several ways, specific G protein-coupled receptors, termed protease-activated receptors (PARs), have been identified, and these have been shown to mediate many of the physiological responses of cells to proteases (14,31).…”