Considering that the ratio between pro-inflammatory to anti-inflammatory/immunoregulatory mediators (IL-10 and TGF-β) in inflamed tissue is more important for RA severity than their absolute levels37 and that both IL-10 and TGF-β act as endogenous analgesics71,72, their production levels in hind paw cultures were explored, as well. Here, IL10 is linked to rheumatoid arthritis.