Sirt1 Inhibits Atrial Fibrosis by Downregulating the Expression of the Transforming Growth Factor-β1/Smad Pathway.

Background: Atrial fibrosis is an important factor leading to atrial fibrillation, and the transforming growth factor-β1/Smad pathway is a key factor in inducing atrial fibrosis. Sirt1 is a member of the histone deacetylase (sirtuin) family, and recent studies have proven its cardioprotective effects.

Objectives: This study explored the effect of Sirt1 on atrial fibrosis through the transforming growth factor-β1/Smad pathway.

Methods: We analyzed human right atrial appendage tissues and explored the relationship between Sirt1 and atrial fibrosis at the morphological, functional and molecular levels by Masson trichrome staining, immunofluorescence, real-time quantitative polymerase chain reaction and Western blot analysis. Rat atrial fibroblasts were extracted and treated by the Sirt1 agonist resveratrol, inhibitor sirtinol, and recombinant human transforming growth factor-β1 protein. The expression levels of related proteins were detected by Western blot, and the effect on the migration of atrial fibroblasts was detected by wound healing assay.

Results: We found that the expression of Sirt1 was reduced in the right atrial appendage tissues of patients with atrial fibrillation, and the degree of fibrosis was increased. In atrial fibroblasts, the activation of Sirt1 could inhibit the expression of transforming growth factor-β1/Smad and reduce the development of fibrosis, while inhibiting Sirt1 reduced its inhibitory effect on the transforming growth factor-β1/Smad pathway.

Conclusions: These findings indicate that Sirt1 inhibits atrial fibrosis by downregulating the expression of the transforming growth factor-β1/Smad pathway, and provide potential targets for the treatment of atrial fibrillation.