Specifically, decreased TIMP1 gene expression in the autoimmunity signature suggests increased MMP activity in target tissues as a result of the lack of feedback mechanism.
In scleroderma (systemic sclerosis, SSc), an autoimmune disorder in which excessive extracellular matrix is deposited in skin and internal organs, one of the suggested contributory factors to the development of fibrosis is a decrease in collagenase activity that may be related to levels of serum tissue inhibitors of metalloproteinases 1 (TIMP-1).