Methods for treating arthritis comprising 14-3-3 antagonists that are capable of specifically binding to extracellularly localized 14-3-3 eta and/or 14-3-3 gamma protein isoforms are provided. In preferred embodiments, the 14-3-3 antagonist is an inhibitory peptide or an anti-14-3-3 antibody. The 14-3-3 antagonists are also formulated in a pharmaceutical composition and used in a method for reducing matrix metalloprotease (MMP) expression in the synovial fluid of a patient, wherein the MMP is MMP-1 or MMP-3.
