Expression of Matrix Metalloproteinases and Tissue Inhibitor of Matrix Metalloproteinases in the Hair Cycle

The study investigated the expression of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) during the hair cycle in mice. It found that MMP-2 and MMP-9 had elevated mRNA and protein expression levels during the anagen phase and decreased levels during the catagen and telogen phases. Their activities fluctuated throughout the hair cycle. TIMP-1 and TIMP-2 expression levels were negatively correlated with MMP-9 and MMP-2, respectively. Immunohistochemical analysis showed that MMP-2 and TIMP-2 were present in all hair follicle structures, while MMP-9 and TIMP-1 were localized to specific areas. These findings suggested that MMP-2 and MMP-9 played significant roles in the hair growth cycle.