TGF-β synergizes with ML264 to block IL-1β-induced matrix degradation mediated by Kruppel-like factor 5 in the nucleus pulposus

Intervertebral disc degeneration causes low back pain.Interleukin-1 beta (IL-1 beta) is a well-known inflammatory mediator that is involved in disc degeneration but its molecular mechanisms on catabolic and anabolic events in nucleus pulposus (NP) cells remain unclear. Kruppel-like factor 5 (KLF5) is associated with inflammation and was previously shown to cause cartilage degradation. In this study, we revealed that KLF5 is involved in IL-1 beta activated NF-kappa B cascade by enhancing both p65 phosphorylation and p65 acetylation. Moreover, the catabolic effect of KLF5 can be abolished by transforming growth factor-beta (TGF-beta) via promoting the proteasomal degradation of KLF5. Therefore, a KLF5 inhibitor ML264 was further proved to synergize with TGF-beta to attenuate IL-1 beta-induced intervertebral disc degeneration. These results indicate the critical role of KLF5 in regulating intervertebral disc metabolism and suggest KLF5 inhibitor such as ML264 as potential compound for treatment of degenerative disc disease.