Bacterial-dependent degradation of host factors may also explain why the only three cytokines detectable in the joints of naïve mice (IL-9, IL-13 and eotaxin), and possibly involved either in cartilage homeostasis55 or in processes of the host immune response56, 57, decreased very early during infection, which could somehow favour S. aureus colonization of the infected joint. This evidence concerns the gene IL13 and infection.