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

Abstract

ABSTRACT.Purpose: We investigated the effects of interleukin-1b (Il-1b) and dexamethasone (Dex) on the expression of matrix metalloprotease-1, -2, -3 and -14 (membrane type-1 MMPÀMT1-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-1b 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-1b (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.

Matrix metalloproteinase 2 activity decreases in human periodontal ligament fibroblast cultures submitted to simulated orthodontic force

“…The stimulus for activation is proteolytic removal of the NH 2 -terminal pro-peptide (Gruber et al 1996;Xu et al 2004). The MMP gelatinase sub-family (MMP-2 and MMP-9) as well as stromelysins (MMP-3 and MMP-10) and matrilisyn (MMP-7) is capable of metabolizing native and denatured collagen, gelatin, elastin, proteoglycan core, and fibronectin (Gruber et al 1996;Quesada et al 1997;Stygar et al 2002;Ehrich et al 2005;Chakrabarti and Patel 2005).…”

“…Many MMPs and TIMPs are regulated at the level of transcription by a variety of growth factors, cytokines, and chemokines (Ra and Parks 2007;Clark et al 2008;Sampieri et al 2008). MMPs can be activated by other MMPs, by extracellular matrix components, and by cytokines (Kapila et al 1996;Cai et al 2005;Ehrich et al 2005;Chakrabarti and Patel 2005).…”

“…MMPs and their specific inhibitors (TIMPs) are secreted to regulate collagen remodeling (Grenier and Mayrand 2001;Burbridge et al 2002;Belotti et al 2003;Balducci et al 2005;Ehrich et al 2005;Chakrabarti and Patel 2005;Wise and King 2008). The expression levels of MMP-2, MMP-8, MMP-9, MMP-13, and TIMPs 1-3 increase transiently during orthodontic tooth movement.…”

Biological properties of trabecular meshwork cells

“…More rigid HTM cells with dense actin networks are less pliable and more likely to inhibit outflow. Dexamethasone downregulates matrix-metalloproteases (MMP)-2, -3, and -14 when the cells are subjected to high pressures (50 mm Hg)(Ehrich et al, 2005). This results less ECM turnover and less outflow.…”

“…This results less ECM turnover and less outflow. Untreated HTM cells subjected to 50 mm Hg pressure had a strong upregulation of MMP-3(Ehrich et al, 2005). It appears the normal response of HTM cells to elevated pressure is to increase the amount of MMP-3 to help degrade and remodel ECM, but the presence of dexamethasone blocks this effect.…”