Evaluation of the Protease Activated Receptor 2 as a Novel Therapeutic Target for COPD

Abstract

Background: COPD is a progressive and life limiting lung condition characterized by restriction of airflow into the lungs. This condition is now the third leading cause of death worldwide, so new research in this area is needed urgently. Protease-activated receptor 2 (PAR2) is a G-protein coupled receptor (GPCR) which has been recognized as an inflammatory receptor, with crosstalk reported with the innate toll-like receptor (TLR) 4. This concept has not been extensively explored in lung epithelial cells, nor has the potential interaction with other TLRs involved in infection-driven exacerbation (TLR2 and TLR3). The aim of this study was to investigate inflammatory responses in lung epithelial cells driven by PAR2 and TLRs known to be involved in exacerbation (TLR3 and 4).

Methods: The bronchial epithelial cell line, BEAS-2B, was used for all experiments. Immunofluorescence (IF) was initially used to establish the presence of PAR2, 3, 4. BEAS-2B cells were stimulated with PAR2 activating peptide FLIGRL or TLR agonists; lipopolysaccharide (LPS) and Poly I:C, in the presence or absence of the PAR2 antagonist AZ8838. After 48 h, IL-6 and IL-8 levels were measured in cell culture supernatants by ELISA.

Results: BEAS-2B cells expressed PAR2, TLR3 and TLR4. PAR2, TLR3 and TLR4 agonists were able to induce significant levels of IL-6 and IL-8 production (inflammatory cytokines) from BEAS-2B cells over a range of concentrations (*P < .05) after a 24-h stimulation period.

Conclusions: Future plans include looking at CRISPR in order to edit out PAR2 and observe inflammatory effects in its absence. PAR2 antagonists will also be used in an attempt to downregulate the impact of PAR2-related inflammation. Human bronchial epithelial cells will be explored as well as COPD HBECs. These cell lines will give a more realistic model and allow for the comparison of healthy and COPD cells.