TNF and rheumatoid arthritis: Since pro-inflammatory cytokines such as IL-1, TNF-α and IL-17 are known to drive the joint pathology in RA by activating inflammatory cells and inducing the release of other mediators such as MMPs and causing osteolysis [34], we investigated whether treatment with either fish oil or krill oil supplemented diets would significantly alter the levels of a range of pro- and anti-inflammatory cytokines.