Aldosterone (Aldo) is involved in extracellular matrix (ECM) remodeling and inflammation leading to heart failure (HF), but its mechanisms remains unknown. Galectin-3 (Gal-3), a β-galactosidase-binding lectin, plays an important role in inflammation and HF. We have investigated whether Gal-3 mediates Aldo-induced ECM remodeling in vascular smooth muscle cells (VSMCs) in vitro and in vivo.Methods
In vitro, primary cultured VSMCs were stimulated with Aldo (10-8M) for 24h, with or without mineralocorticoid receptor (MR) antagonists (eplerenone, RU28318) and Gal-3 inhibitors (modified citrus pectin, N-acetyllactosamine, lactose). Gal-3 was over-expressed (transfection) and knocked-down (siRNA). In vivo, Wistar rats were treated with Aldo (1mg/kg/day) + salt or Aldo + salt + spironolactone (200mg/kg/day) for 3 weeks. Gal-3 expression, ECM production (collagen type I and III, fibronectin and elastin) and degradation (MMP activities) were evaluated by RT-PCR, Western blot, zymography and immunohistochemistry in VSMCs and aorta.Results
Gal-3 was spontaneously expressed in cultured VSMCs. Its over-expression enhanced collagen type I production. Aldo up-regulated Gal-3 levels in a dose- and time-dependent manner via the mineralocorticoid receptor. Gal-3 chemical inhibitors blocked Aldo-induced ECM protein production. In addition, Gal-3 silencing abolished Aldo-induced collagen type I synthesis. In Aldo-salt hypertensive rats, aortic Gal-3 expression, ECM proteins and MMP activities were enhanced. Spironolactone treatment reversed all the above effects. Aortic Gal-3 expression was positively correlated with vascular collagen type I, elastin, MMP-2 and MMP-13 activities.Conclusions
Aldo up-regulates Gal-3 expression via its mineralocorticoid receptor in VSMCs in vitro and in vivo. Gal-3 over-expression induces collagen type I synthesis. Moreover, Gal-3 is required for the fibrotic response to Aldo. Our data suggest a key role for Gal-3 in Aldo-induced vascular collagen accumulation.