Oxygen tension modulates the effects of TNFα in compressed chondrocytes

Abstract

Objective and designOxygen tension and biomechanical signals are factors that regulate inflammatory mechanisms in chondrocytes. We examined whether low oxygen tension influenced the cells response to TNFα and dynamic compression.Materials and methodsChondrocyte/agarose constructs were treated with varying concentrations of TNFα (0.1–100 ng/ml) and cultured at 5 and 21 % oxygen tension for 48 h. In separate experiments, constructs were subjected to dynamic compression (15 %) and treated with TNFα (10 ng/ml) and/or L-NIO (1 mM) at 5 and 21 % oxygen tension using an ex vivo bioreactor for 48 h. Markers for catabolic activity (NO, PGE2) and tissue remodelling (GAG, MMPs) were quantified by biochemical assay. ADAMTS-5 and MMP-13 expression were examined by real-time qPCR. 2-way ANOVA and a post hoc Bonferroni-corrected t test were used to analyse data.ResultsTNFα dose-dependently increased NO, PGE2 and MMP activity (all p < 0.001) and induced MMP-13 (p < 0.05) and ADAMTS-5 gene expression (pp < 0.01) with values greater at 5 % oxygen tension than 21 %. The induction of catabolic mediators by TNFα was reduced by dynamic compression and/or L-NIO (all p < 0.001), with a greater inhibition observed at 5% than 21 %. The stimulation of GAG synthesis by dynamic compression was greater at 21 % than 5 % oxygen tension and this response was reduced with TNFα or reversed with L-NIO.ConclusionsThe present findings revealed that TNFα increased production of NO, PGE2 and MMP activity at 5 % oxygen tension. The effects induced by TNFα were reduced by dynamic compression and/or the NOS inhibitor, linking both types of stimuli to reparative activities. Future therapeutics should develop oxygen-sensitive antagonists which are directed to interfering with the TNFα-induced pathways.

Ultrasound Protects Human Chondrocytes from Biochemical and Ultrastructural Changes Induced by Oxidative Stress

“…Our results are in accordance with a previous studies in which US exposure reduced the TNF-α plasmatic level in rabbit OA [41] and tissular TNF-α synthesis after muscle contusion [64]. In a study published by Tilwani, it was demonstrated that in chondrocytes' cultures biomechanical signals attenuated TNF-α-induced synthesis of NO, PGE 2 , and MMPs [22], molecules involved in chondrocytes and cartilage injury. Similarly, in our experimental model mechanical energy provided by US attenuated OS, TNF-α synthesis, so alleviating ultrastructural chondrocyte damages.…”

“…TNF-α can also induce nitric oxide (NO), prostaglandin E 2 (PGE 2 ), and IL-6 synthesis and activate c-Jun N-terminal kinases (JNKs), which are responsible for upregulating proapoptotic genes and inactivating antiapoptotic proteins Bcl-2/Bcl-xL in OA chondrocytes [22][23][24][25].…”

Effect of a Moderate-Intensity Aerobic Training on Joint Biomarkers and Functional Adaptations in Rats Subjected to Induced Knee Osteoarthritis

“…Thus, active mechanotransduction induces changes in oxygen tension and subsequent positive effects on matrix synthesis and cell growth (Urban, 1994; Park et al, 2004). These effects are explained by the displacement of growth factors or cellular cytokines by shifting cellular metabolism (Tilwani et al, 2017). Finally, our results showed that the proposed training offered an inflammatory control, confirmed by the modulation effect in biomarkers levels (IL1β and TNF in the joint wash; IL10 and IL6 in the knee joint).…”

Mechanical loading inhibits cartilage inflammatory signalling via an HDAC6 and IFT-dependent mechanism regulating primary cilia elongation

“…Isolated chondrocytes were subjected to equibiaxial cyclic tensile strain (CTS) at 0.33 Hz, 0–10% strain using the Flexcell FX-5000T™ system (Flexcell Corp, PA). Cartilage explants were subjected to cyclic compressive strain (CCS) at 0.33 Hz, 0–10% peak strain using a well-established Bose loading system as previously described 16 . Explants were mounted in a standard 24 well plate with each explant centrally located within a washer.…”