Downregulation of FPR1 abates lipopolysaccharide-induced inflammatory injury and apoptosis by upregulating MAPK signaling pathway in murine chondrogenic ATDC5 cells

Abstract

Background and objective: Osteoarthritis is the most common chronic osteoarthrosis disease. There are complex factors that lead to osteoarthritis. Therefore, it is essential to investigate the molecular mechanism of osteoarthritis, especially the mechanism of articular cartilage degeneration. In this study, the mechanism of FPR1 (formyl peptide receptor 1) in LPS (lipopolysaccharide) induced chondrogenic cell ATDC5 was investigated.Materials and methods: We employed real-time quantitative polymerase chain reaction (RT-qPCR) and western blot assay to analyze the expression level of FPR1 in ATDC5 cell linesinduced by LPS at 0, 2.5, 5, and 10 μg/mL concentrations. Then we constructed the FPR1 knockdown plasmid to transfect the LPS-ATDC5. MTT assay was used to test cell viability in control, LPS, LPS+shNC and LPS+shFPR1 groups. ELISA and RT-qPCR assay were employed to examine the TNF-α (tumor necrosis factor-α)、IL-6 and IL-1β expression level. Flow cytometry and western blot assay were employed to analyze the apoptosis of LPS-ATDC5. Finally, we utilized the western blot assay to text related protein expression level of MAPK (mitogen-activated protein kinase) signaling pathway.Results: In this study, we found the expression level of FPR1 was increased in LPS-ATDC5, downregulation of FPR1 improves the survival rate and alleviates inflammatory response of LPS-ATDC5. Meanwhile, downregulation of FPR1 alleviates apoptosis of LPS-ATDC5. Finally, downregulation of FPR1 inhibits the MAPK signal pathway.Conclusion: Present study revealed that FPR1 was highly expressed in LPS-induced chondrocytes ATDC5, and the downregulation of FPR1 abated the inflammatory response and apoptosis of LPS-ATDC5 cells by regulating the MAPK signaling pathway.