TIMP1 and gingival overgrowth: The alteration in the concentrations of these two cytokines may play a central role in the pathogenesis of drug induced gingival overgrowth: IL-1ß leads to the production of metalloproteinase (MMP), inducing connective tissue degradation, while IL-6 is responsible for the increase of metallopeptidase expression (TIMP), inhibiting tissue breakdown.