Do mechanical strain and TNF-α interact to amplify pro-inflammatory cytokine production in human annulus fibrosus cells?

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• 作者：Morakot Likhitpanichkul^a ; ^{morakotl@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Olivia M. Torre^a ; ^{olivia.torre@icahn.mssm.edu" class="auth_mail" title="E-mail the corresponding author} ; Jadry Gruen^a ; ^{jadry.gruen@stonybrookmedicine.edu" class="auth_mail" title="E-mail the corresponding author} ; Benjamin A. Walter^a ; ^b ; ^{benjamin.walter@mssm.edu" class="auth_mail" title="E-mail the corresponding author} ; Andrew C. Hecht^a ; ^{andrew.hecht@mountsinai.org" class="auth_mail" title="E-mail the corresponding author} ; James C. Iatridis^a ; ^{james.iatridis@mssm.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：AF ; annulus fibrosus ; IVD ; intervertebral disc ; IL ; interleukin ; TNF-α ; tumor necrosis factor-α ; DMEM ; Dulbecco׳s Modified Eagles Media ; ELISA ; Enzyme linked immunosorbant assay
• 刊名：Journal of Biomechanics
• 出版年：2016
• 出版时间：3 May 2016
• 年：2016
• 卷：49
• 期：7
• 页码：1214-1220
• 全文大小：3968 K

文摘

During intervertebral disc (IVD) injury and degeneration, annulus fibrosus (AF) cells experience large mechanical strains in a pro-inflammatory milieu. We hypothesized that TNF-α, an initiator of IVD inflammation, modifies AF cell mechanobiology via cytoskeletal changes, and interacts with mechanical strain to enhance pro-inflammatory cytokine production. Human AF cells (N=5, Thompson grades 2–4) were stretched uniaxially on collagen-I coated chambers to 0%, 5% (physiological) or 15% (pathologic) strains at 0.5 Hz for 24 h under hypoxic conditions with or without TNF-α (10 ng/mL). AF cells were treated with anti-TNF-α and anti-IL-6. ELISA assessed IL-1β, IL-6, and IL-8 production and immunocytochemistry measured F-actin, vinculin and α-tubulin in AF cells. TNF-α significantly increased AF cell pro-inflammatory cytokine production compared to basal conditions (IL-1β:2.0±1.4–84.0±77.3, IL-6:10.6±9.9–280.9±214.1, IL-8:23.9±26.0–5125.1±4170.8 pg/ml for basal and TNF-α treatment, respectively) as expected, but mechanical strain did not. Pathologic strain in combination with TNF-α increased IL-1β, and IL-8 but not IL-6 production of AF cells. TNF-α treatment altered F-actin and α-tubulin in AF cells, suggestive of altered cytoskeletal stiffness. Anti-TNF-α (infliximab) significantly inhibited pro-inflammatory cytokine production while anti-IL-6 (atlizumab) did not. In conclusion, TNF-α altered AF cell mechanobiology with cytoskeletal remodeling that potentially sensitized AF cells to mechanical strain and increased TNF-α-induced pro-inflammatory cytokine production. Results suggest an interaction between TNF-α and mechanical strain and future mechanistic studies are required to validate these observations.