Abstract
BackgroundLow-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.MethodsHuman 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.ResultsLIPUS 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.ConclusionLIPUS inhibited inflammation and catabolism through the NF‐κB pathway in human degenerative nucleus pulposus cells.
Highlights
Low-intensity pulsed ultrasound (LIPUS) is a safe and noninvasive rehabilitative physical therapy with anti-inflammatory effects
Many studies have shown that proinflammatory factors such as Tumor necrosis factor-α (TNF-α) and IL-1β stimulate the expression of matrix metalloproteinase (MMP) and induce nucleus pulposus (NP) cell apoptosis, resulting in the loss of collagen and proteoglycans and leading to intervertebral disc degeneration [5, 6]
Choosing an appropriate LIPUS intensity to inhibit of TNF‐α and IL‐1β in LPS‐induced human NP cells To determine the effect of LIPUS on inflammatory factors in NP cells, ELISA (Fig. 1a) and RT-PCR (Fig. 1b) were used to measure the gene and protein expression of TNF-α and IL‐1β
Summary
Low-intensity pulsed ultrasound (LIPUS) is a safe and noninvasive rehabilitative physical therapy with anti-inflammatory effects. Intervertebral disc degeneration is the initial factor in spinal degenerative diseases and one of the main causes of low back pain, which has caused serious economic and social burdens [1]. The current treatment methods for intervertebral disc degeneration mainly include conservative treatment and surgical treatment. Many studies have confirmed that an excessive inflammatory response in NP cells is an important cytological pathological feature of degenerative intervertebral disc tissues [3, 4]. Many studies have shown that proinflammatory factors such as TNF-α and IL-1β stimulate the expression of matrix metalloproteinase (MMP) and induce NP cell apoptosis, resulting in the loss of collagen and proteoglycans and leading to intervertebral disc degeneration [5, 6]. Regulation of the NF‐κB pathway may play a key role in the inflammatory control and catabolism of NP cells
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