The mannan (Saccharomyces Cerevisiae) induced PsA model (MiP) in mice is a newly developed model in which both skin lesions resembling those seen in Ps as well as the joint inflammation of PsA can be found. Disease is mediated by TNF-a produced by macrophages which leads to T cell activation and IL-17A production. The increased level of IL-17A recruit neutrophils to joint and skin and results in an inflammatory response. Repeated mannan injections (every 7th day) give rise to a chronic relapsing disease.

Onset of joint and skin inflammation is seen within a few days after the mannan injection and slowly heals out after one week if not reactivated by a second mannan injection. In addition to the clinical evaluation of inflammation, disease progression is also accompanied by increased number of cells in the spleen.