Overexpression of growth and differentiation factor-5 inhibits inflammatory factors released by intervertebral disc cells.

Low back pain (LBP) is one of the most common musculoskeletal diseases in the world. The incidence is ~70% in adults and many of them suffer from disability. Recently, intervertebral disc degeneration (IDD) has been deemed as a main cause of LBP. The present study aimed to investigate the potentials of growth and differentiation factor-5 (GDF-5) in IDD. The protein levels of prostaglandin-E2 (PGE2), tumor necrosis factor (TNF)-α and interleukin (IL)-1β in culture medium were evaluated by ELISA. mRNA and protein expression levels in nucleus pulposus (NP) cells were evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting, respectively. Griess reaction was applied to test the nitric oxide (NO) concentration in the culture supernatant. The expression levels of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in NP cells were measured by RT-qPCR. Collagen-II, aggrecan, IκBα and phosphorylated (p)-p65 expression levels were detected by western blotting. Compared with the control group, protein expression levels of TNF-α, IL-1β and PGE2, and NO concentration in culture medium were upregulated by LPS, which were significantly repressed by GDF-5 overexpression (P<0.05). Additionally, GDF-5 overexpression reduced lipopolysaccharide-induced upregulation of TNF-α, IL-1β, iNOS, COX-2, collagen-II, aggrecan, IκBα and p-p65 expression levels in NP cells.