In the present study we showed that whereas administration of MDP to WT mice with anti-collagen arthritis such administration to mice with a KI Blau mutation with DSS-colitis did not; in addition, inflamed joint tissue induced in Blau KI mice by administration of anti-collagen antibody expressed greatly decreased levels of IRF4 as compared to comparable inflamed joint tissue in littermate control mice. Here, IRF4 is linked to colitis.