Inhibitory effect of FSLLRY-NH₂ on inflammatory responses induced by hydrogen peroxide in HepG2 cells

Proteinase activated receptor 2 (PAR2), which is localized in the GI tract, the respiratory system, and the kidney tubules is a G protein-coupled receptor associated with inflammation, metabolism, and disease. The aim of this study was to explore the role of PAR2 in hydrogen peroxide (H₂O₂)-induced HepG2 cells by using FSLLRY-NH₂ a PAR2 antagonist. H₂O₂ treatment resulted in induction of PAR2 in esophageal, gastric, and liver cells, with the most robust response being in HepG2 cells. Furthermore, this effect was dose-dependent in HepG2 cells. Treatment with H₂O₂ at concentrations above 400 μM for 24 h also reduced HepG2 cell viability. H₂O₂ treatment increased both the protein and mRNA levels of IL-1β, IL-8, and TNF-α, as well as those of SAPK/JNK. The increased levels of these pro-inflammatory genes and SAPK/JNK induced by H₂O₂ were attenuated in a dose-dependent manner when cells were co-treated with H₂O₂ and FSLLRY-NH2. In summary, the PAR2 antagonist peptide, FSLLRY-NH2, reduces the level of the pro-inflammatory genes IL-8, IL-1β, and TNF-α induced by H₂O₂, through the SAPK/JNK pathways in HepG2 cells. These data suggest that a PAR2 antagonist could be an anti-inflammatory agent in HepG2 cells.