Targeting protease activated receptor-1 with P1pal-12 limits bleomycin-induced pulmonary fibrosis

Protease Activated Receptor-1 Deficiency Diminishes Bleomycin-Induced Skin Fibrosis

“…Overall, these data suggest that HDF proliferation is PAR-1 dependent. Although P1pal-12 is used frequently as a specific PAR-1 inhibitor (8) and no toxicity has been described, we next aimed to confirm that PAR-1 drives HDF proliferation. To this end, HDFs were lentivirally transduced with two different PAR-1 shRNA constructs (designated 3689 and 3691) and a control shRNA construct (003).…”

“…Removal of the N-terminal extracellular domain releases a tethered ligand that binds to the body of the receptor to induce transmembrane signaling (7). Interestingly, PAR-1 induces proliferation, migration and ECM production of fibroblasts and PAR-1 deficiency (either genetic or pharmacologic) limits experimental fibrosis in lung (8,9) and liver (10). In the skin, PAR-1 is expressed on keratinocytes, endothelial cells and fibroblasts and the density of PAR-1 positive fibroblasts is increased in the skin of SSc patients compared with that of healthy controls (11).…”

Pharmacological Targeting of Protease-Activated Receptor 2 Affords Protection from Bleomycin-Induced Pulmonary Fibrosis

“…In the present study, we aimed to address the controversy and provide several lines of evidence to support the crucial role of PAR-2 in the progression of pulmonary fibrosis. Bleomycin-induced pulmonary fibrosis is stably formed at around d 14, which is consequently frequently used as an endpoint in the literature (19,28,37). However, the fibrotic stage induced by bleomycin peaks at around 3-4 wks and the reduction in fibrosis observed in PAR-2-deficient mice at d 14 (19,30) may thus indicate only a delay in the onset of fibrosis instead of reduced progression.…”

“…To this end, mice were intranasally instilled with different concentrations of P2pal-18S (based on previous experiments showing that a similar pepducinbased inhibitor [P1pal-12; PAR-1 inhibitor] was effective at doses of 2.5 and 10 mg/kg but not at a dose of 0.5 mg/kg [28]), after which the extent and severity of fibrosis was determined at d 14. As shown in Figure 3A, bleomycin instillation resulted in extensive fibrotic foci accompanied by increased deposition of ECM.…”

“…Hydroxyproline analysis was performed by the hydroxyproline assay kit per the manufacturer's instructions (SigmaAldrich) and as described before (28).…”