Bornyl acetate has an anti-inflammatory effect in human chondrocytes via induction of IL-11

Both pro-inflammatory cytokines and anti-inflammatory cytokines generated by chondrocytes play essential roles in the process of Rheumatoid arthritis and osteoarthritis (OA). Bornyl acetate is the main volatile constituent in numerous conifer oils and some Chinese traditional herbs, which has displayed an anti-inflammatory effect before. In this study, we found that bornyl acetate elevates the expression of IL-11 at both the mRNA and protein levels. Interestingly, our results indicated that IL-1β-mediated up-regulation of IL-6, IL-8, MMP-1, and MMP-13 was significantly compromised by IL-11 co-treatment on mRNA levels and protein levels. The antagonistic effects of bornyl acetate on IL-1β induced targets MMP-1 and MMP-13 were diminished by IL-11 knockdown. Mechanistically, our results indicated that bornyl acetate significantly elevates the expression of AP-1 component c-fos, which may influence gross AP-1 activity and initial the transcription of IL-11. Indeed, expression of IL-11 was reversed upon c-fos knockdown. Our results suggest the therapeutic potentials of bornyl acetate in patients with OA.