Effects of interleukin-1beta and dexamethasone on the expression of matrix metalloprotease mRNA by trabecular cells exposed to elevated hydrostatic pressure.

PURPOSE

We investigated the effects of interleukin-1beta (Il-1beta) and dexamethasone (Dex) on the expression of matrix metalloprotease-1, -2, -3 and -14 (membrane type-1 MMP-MT1-MMP) as well as tissue inhibitors of matrix metalloproteases (TIMP-1 and -2) mRNA by trabecular cells exposed not only to normal, but also to elevated levels of hydrostatic pressure.

METHODS

Confluent primary cultures of porcine trabecular cells were incubated in a serum-free medium (SFM) as controls, or in SFM containing either 10 ng/ml Il-1beta or 10 nm Dex and exposed to pressures of 15 mmHg or 50 mmHg (corresponding to normal and high intraocular pressure, respectively) in specially designed pressure chambers. After 72 hours, total RNA was extracted from the harvested cells, reverse transcribed and amplified using primers specific to MMP-1, -2, -3 and -14, and TIMP-1 and -2.

RESULTS

The most significant changes were detected in the levels of MMP-3 mRNA in control cells (2.4-fold increase), of TIMP-1 and -2 mRNA in cells treated with Il-1beta (2.6-fold increase) and of MMP-3 mRNA in cells treated with Dex (3.5-fold increase) exposed to 50 mmHg pressure.

CONCLUSION

Because MMP-3 (stromelysin) mRNA showed the highest upregulation, our findings suggest that trabecular cells preferentially degrade and turn over the proteoglycan components of the extracellular matrix in response to short-term exposure to increased hydrostatic pressure with and without Dex as a homeostatic mechanism.