Cytokine-induced Expression of Inflammatory Genes in Tendon Cells

IL-1β and IFNγ respectively induce NF-κB and IFN target genes expressed in diseased shoulder tendon tissues8 11 (link) and were also identified in diseased Achilles tendon tissues in the current study. We therefore investigated if treatment of cultured tendon cells with these cytokines induced more profound expression of SFA markers and NF-κB and IFN target genes in diseased relative to healthy tendon-derived cells. Tendon-derived cells were isolated from healthy hamstring and diseased Achilles tendons using previously described protocols11 (link); passage 1–3 cells were used for all experiments. Cells were grown until 80% confluence prior to stimulation with IL-1β (10 ng/mL, Sigma) or IFN gamma (20 ng/mL, BioLegend) in medium (DMEM F12, Lonza) containing 1% heat-inactivated human serum (Sigma). Non-treated (vehicle only) cells served as experimental controls. After cytokine/vehicle treatment, cells were incubated at 37°C and 5% CO₂ for 24 hours until experimental harvest for mRNA or flow cytometry.