Abstract
The mechanisms underpinning the failure of inflammation to resolve in diseased musculoskeletal soft tissues are unknown. Herein, we studied bioactive lipid mediator (LM) profiles of tendon-derived stromal cells isolated from healthy donors and patients with chronic tendinopathy. Interleukin(IL)-1β treatment markedly induced prostaglandin biosynthesis in diseased compared to healthy tendon cells, and up regulated the formation of several pro-resolving mediators including 15-epi-LXA4 and MaR1. Incubation of IL-1β stimulated healthy tendon cells with 15-epi-LXA4 or MaR1 down-regulated PGE2 and PGD2 production. When these mediators were incubated with diseased cells, we only found a modest down regulation in prostanoid concentrations, whereas it led to significant decreases in IL-6 and Podoplanin expression. In diseased tendon cells, we also found increased 15-Prostaglandin Dehydrogenase (15-PGDH) expression as well as increased concentrations of both 15-epi-LXA4 and MaR1 further metabolites, 15-oxo-LXA4 and 14-oxo-MaR1. Inhibition of 15-PGDH using either indomethacin or SW033291 significantly reduced the further conversion of 15-epi-LXA4 and MaR1 and regulated expression of IL-6, PDPN and STAT-1. Taken together these results suggest that chronic inflammation in musculoskeletal soft tissues may result from dysregulated LM-SPM production, and that inhibition of 15-PGDH activity together with promoting resolution using SPM represents a novel therapeutic strategy to resolve chronic tendon inflammation.