LIPUS inhibits inflammation and catabolism through the NF‐κB pathway in human degenerative nucleus pulposus cells

Abstract Background Low-intensity pulsed ultrasound (LIPUS) is a safe and noninvasive rehabilitative physical therapy with anti-inflammatory effects. The current study investigated the effect of LIPUS on the inflammation of nucleus pulposus (NP) cells and its underlying mechanism. Methods Human NP cells were acquired from lumbar disc herniation tissue samples and cultured for experiments. Human NP cells were treated with LPS and then exposed to LIPUS (15 mW/cm2, 30 mW/cm2 and 60 mW/cm2) for 20 min daily for 3 days to determine the appropriate intensity to inhibit the expression of the inflammatory factors TNF-α and IL-1β. The gene and protein expression of aggrecan, collagen II, MMP-3 and MMP-9 was measured by real‐time PCR and western blotting, respectively. The activity of the nuclear factor‐kappa B (NF‐κB) pathway was examined by western blotting and immunofluorescence. After pretreatment with the NF-κB inhibitor PDTC, the expression of TNF-α, IL-1β, MMP-3 and MMP-9 was measured by real‐time PCR. Results LIPUS at intensities of 15 mW/cm2, 30 mW/cm2 and 60 mW/cm2 inhibited LPS-induced NP cell expression of the inflammatory factors TNF-α and IL-1β, especially at 30 mW/cm2. LIPUS significantly upregulated the gene and protein expression of aggrecan and collagen II and downregulated the gene and protein expression of MMP-3 and MMP-9 in LPS-induced NP cells. The NF‐κB signaling pathway was inhibited by LIPUS through inhibiting the protein expression of p-P65 and the translocation of P65 into the nucleus in LPS-induced NP cells. In addition, LIPUS had similar effects as the NF-κB inhibitor PDTC by inhibiting the NF-κB signaling pathway, inflammation and catabolism in LPS-induced human degenerative nucleus pulposus cells. Conclusion LIPUS inhibited inflammation and catabolism through the NF‐κB pathway in human degenerative nucleus pulposus cells.