The Role of TIMP3 in Microvascular Endothelial Cell-Extracellular Matrix Interaction and Regulation of Microvascular Barrier Function

Nidhi Kulkarni, The University of Western Ontario

Abstract

Pulmonary microvascular endothelial cell (PMVEC) interactions with the extracellular matrix (ECM) mediates PMVEC barrier function. Further, data suggests an association between decreased PMVEC-ECM interactions under proinflammatory conditions and PMVEC barrier dysfunction. Tissue inhibitor of metalloproteinases 3 (TIMP3) may also regulate barrier function, as PMVEC from Timp3^-/-mice show increased leak. Studies in the developing lung also showed TIMP3 regulating PMVEC-ECM interactions. Based on this, I hypothesized that TIMP3 maintains PMVEC barrier function by promoting PMVEC-ECM interactions.

Using the XperT-permeability assay, Timp3^-/-PMVEC demonstrated enhanced leak vs. WT PMVEC, particularly under proinflammatory conditions, and this was associated with decreased phosphorylated focal adhesion kinase (pFAK). Furthermore, FAK inhibition increased leak in WT PMVEC, and enhanced leak in Timp3^-/-PMVEC under proinflammatory conditions. Finally, MMP inhibition attenuated leak in Timp3^-/-PMVEC under both basal and proinflammatory conditions

These results suggest a role for TIMP3 in mediating PMVEC-ECM interactions and promoting PMVEC barrier function.