title: Phosphorylation of osteopontin has proapoptotic and proinflammatory effects on human knee osteoarthritis chondrocytes.
abstract: The aim of the present study was to investigate the effects of phosphorylated osteopontin (p-OPN) on apoptosis and pro-inflammatory cytokine expression in human knee osteoarthritis (OA) chondrocytes. Human knee OA chondrocytes obtained from patients who underwent total knee arthroplasty were treated with p-OPN, OPN or buffer. Reverse transcription quantitative-polymerase chain reaction (RT-qPCR) and western blot analysis were used to assess the expression levels of proinflammatory factors, including interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6 and nuclear factor (NF)-κB. Apoptosis of human knee OA chondrocytes was detected by Annexin V-fluorescein isothiocyanate/propidium iodide flow cytometry. Compared with the controls, chondrocytes treated with OPN exhibited higher mRNA and protein expression levels of proinflammatory factors (IL-1β, TNF-α, IL-6 and NF-κB), and a higher percentage of apoptotic chondrocytes. Furthermore, chondrocytes treated with p-OPN exhibited the highest mRNA and protein expression levels of proinflammatory factors (IL-1β, TNF-α, IL-6, NF-κB) and the highest percentage of apoptotic chondrocytes. p-OPN induces chondrocyte apoptosis and proinflammatory factor release, which suggests that p-OPN may contribute to OA pathogenesis, and inhibition of p-OPN may provide a novel effective strategy to slow or halt OA progression.
authors.affiliation: Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China.
authors.forename: Shu-Guang
authors.initials: SG
authors.lastname: Gao
authors.affiliation: Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China; Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450000, P.R. China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China.
authors.forename: Chao
authors.initials: C
authors.lastname: Zeng
authors.affiliation: Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China; Department of Orthopedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450000, P.R. China.
authors.forename: Shi-Tao
authors.initials: ST
authors.lastname: Lu
authors.affiliation: Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Tian
authors.affiliation: Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China; Department of Orthopedics, Yiyang Central Hospital, Yiyang, Hunan 413000, P.R. China.
authors.forename: Chao
authors.initials: C
authors.lastname: Cheng
authors.affiliation: Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China; Department of Orthopedics, Changsha Central Hospital, Changsha, Hunan 410004, P.R. China.
authors.forename: Liang-Jun
authors.initials: LJ
authors.lastname: Li
authors.affiliation: Department of Orthopedics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China; Research Center of Clinical Skills of Joint Surgery of Hunan Province, Changsha, Hunan 410008, P.R. China.
authors.forename: Guang-Hua
authors.initials: GH
authors.lastname: Lei
keywords: apoptosis; chondrocyte; osteoarthritis; osteopontin; phosphorylation