A role for fumarate hydratase in mediating oxidative effects of galectin-3 in human cardiac fibroblasts.

AIMS

Galectin-3 (Gal-3), a β-galactoside-binding lectin involved in cardiac inflammation and fibrosis, could regulate oxidative stress, although the mechanisms have not been elucidated. We herein investigated the changes in oxidative stress-related mediators induced by Gal-3 in human cardiac fibroblasts and in pathological animal and human models of cardiac diseases.

RESULTS

Using quantitative proteomics and immunodetection approaches, we have identified that Gal-3 down-regulated fumarate hydratase (FH) in human cardiac fibroblasts. In parallel, Gal-3 increased fumarate production in a time-dependent manner. Gal-3 treatment enhanced carbonylated proteins detected through OxyBlot technique. Interestingly, treatment of cells with fumarate induced oxidative stress, enhanced fibroblast activation markers and increased collagen and interleukin-6 secretion. In Gal-3-silenced cells and in heart from Gal-3 knock-out mice, FH was increased and fumarate was decreased. In myocardial biopsies from patients with aortic stenosis (AS, n=26), FH levels were decreased as compared to Controls (n=13). Cardiac Gal-3 inversely correlated with FH levels in myocardial biopsies. In an experimental model of AS rats, pharmacological inhibition of Gal-3 restored cardiac FH, decreased fumarate concentration and improved oxidative status.

CONCLUSION

In human cardiac fibroblasts, Gal-3 decreased FH expression increasing fumarate concentration and promoting oxidative stress. In human AS, cardiac levels of Gal-3 inversely associated with FH. Gal-3 blockade restored FH and improved fumarate and oxidative stress status in AS rats. FH is therefore a key molecule mediating Gal-3-induced oxidative stress in cardiac cells.