Protease–Activated Receptors Regulate MMP and TIMP Expression in Human Corneal Epithelial Cells

Abstract

Abstract: : Purpose: Protease–activated receptors (PARs) are a novel family of G–protein–coupled receptors that are expressed on a variety of cell types. PAR activation by specific proteases is capable of modulating a wide range of biologic processes including inflammation, angiogenesis, wound healing, and tissue repair. We have previously reported that human corneal epithelial cells express functional PAR–1 and PAR–2. The objective of this study was to determine if PARs can modulate the production of corneal epithelial cell derived matrix metalloproteases (MMPs) and tissue inhibitors of metalloproteases (TIMPs). PAR regulation of MMPs and TIMPs production in corneal epithelial cells may have an important role in mediating inflammatory and wound healing responses in the cornea. Methods: The effect of specific PAR agonists on MMP–1, MMP–2, MMP–8 and MMP–9 as well as TIMP–1 and TIMP–2 production in HCE–T human corneal epithelial cells was determined. MMP and TIMP mRNA expression was determined by real time RT–PCR, secreted protein levels was measured in cell culture supernatants by ELISA, and bioactivity will be assessed by specific zymography studies Results: PAR–1, PAR–2, and PAR–4 activation in HCE–T corneal epithelial cells resulted in increased MMP–1, MMP–2 and MMP–9 mRNA expression and protein secretion. Likewise HCE–T TIMP–1 and TIMP–2 mRNA, protein, and bioactivity was induced by activation of PAR–1, PAR–2, and PAR–4. PAR activation had no effect on HCE–T MMP–8 production. Conclusions: These studies demonstrate for the first time that PAR activation of human corneal epithelial cells results in increased production of specific MMPs and TIMPs which may have important consequences for a variety of inflammatory, wound healing, and tissue repair responses in the cornea.

Keywords: cornea: epithelium • wound healing • inflammation