ABSTRACT
Abstract Protease-activated receptor-2 (PAR2) is associated with the pathogenesis of many chronic diseases with inflammatory characteristics, including periodontitis. This study aimed to evaluate how the activation of PAR2 can affect the osteogenic activity of human periodontal ligament stem cells (PDLSCs) in vitro. PDLSCs collected from three subjects were treated in osteogenic medium for 2, 7, 14, and 21 days with trypsin (0.1 U/mL), PAR2 specific agonist peptide (SLIGRL-NH2) (100 nM), and PAR2 antagonist peptide (FSLLRY-NH2) (100 nM). Gene (RT-qPCR) expression and protein expression (ELISA) of osteogenic factors, bone metabolism, and inflammatory cytokines, cell proliferation, alkaline phosphatase (ALP) activity, alizarin red S staining, and supernatant concentration were assessed. Statistical analysis of the results with a significance level of 5% was performed. Activation of PAR2 led to decreases in cell proliferation and calcium deposition (p < 0.05), calcium concentration (p < 0.05), and ALP activity (p < 0.05). Additionally, PAR2 activation increased gene and protein expression of receptor activator of nuclear factor kappa-Β ligand (RANKL) (p < 0.05) and significantly decreased the gene and protein expression of osteoprotegerin (p <0. 05). Considering the findings, the present study demonstrated PAR2 activation was able to decrease cell proliferation, decreased osteogenic activity of PDLSCs, and upregulated conditions for bone resorption. PAR2 may be considered a promising target in periodontal regenerative procedures.
ABSTRACT
Abstract: PAR1 is a G-coupled protein receptor that regulates several cellular metabolism processes, including differentiation and proliferation of osteogenic and cementogenic related cells and our group previously demonstrated the regenerative potential of PAR1 in human periodontal ligament stem cells (hPDLSCs). In this study, we hypothesized that PAR1 regulates the cementogenic differentiation of hPDLSCs. Our goal was to identify the intracellular signaling pathway underlying PAR1 activation in hPDSLC differentiation. hPDLSCs were isolated using the explant technique. Cells were cultured in an osteogenic medium (OST) (α-MEM, 15% fetal bovine serum, L-glutamine, penicillin, streptomycin, amphotericin B, dexamethasone, and beta-glycerophosphate). The hPDLSCs were treated with a specific activator of PAR1 (PAR1 agonist) and blockers of the MAPK/ERK and PI3K pathways for 2 and 7 days. The gene expression of CEMP1 was assessed by RT-qPCR. The activation of PAR1 by its agonist peptide led to an increase in CEMP1 gene expression when compared with OST control. MAPK/ERK blockage abrogated the upregulation of CEMP1 gene expression induced by PAR1 agonist (p < 0.05). PI3K blockage did not affect the gene expression of CEMP1 at any experimental time (p > 0.05). We concluded that CEMP1 gene expression increased by PAR1 activation is MAPK/ERK-dependent and PI3K independent, suggesting that PAR1 may regulate cementogenetic differentiation of hPDLSCs.