Increased TGFβ1 and SMAD3 Contribute to Age-Related Aortic Valve Calcification

Area of Science:

• Cardiovascular Biology
• Aging Research
• Molecular Biology

Background:

• Calcific aortic valve disease (CAVD) is a prevalent heart condition in the elderly, currently managed with challenging surgical valve replacement.
• The aging-suppressor gene klotho plays a critical role in aortic valve calcification, with klotho knockout mice exhibiting severe calcification and reduced lifespan.
• Increased TGFβ1 and SMAD3 signaling are associated with AV calcification in klotho-deficient models.

Purpose of the Study:

• To investigate the potential of inhibiting TGFβ1 and SMAD3 signaling pathways to rescue aortic valve calcification.
• To determine the contribution of TGFβ1 and SMAD3 to AV calcification in klotho knockout mice.

Main Methods:

• Generated klotho knockout mice with heterozygous deficiency in Tgfb1 or Smad3.
• Evaluated aortic valve calcification using histological and morphometric analyses.
• Assessed gene expression of key calcification markers and TGFβ signaling components via mRNA and Western blot analyses.

Main Results:

• Significant reduction in aortic valve calcification was observed in klotho knockout mice with heterozygous deletion of Tgfb1 or Smad3.
• Smad3 heterozygous deletion was more potent in reducing AV calcification than Tgfb1 heterozygous deletion.
• Inhibition of TGFβ1, Pai1, Bmp2, Alk2, Spp1, and Runx2 mRNA expression was noted in both genetically modified groups.
• Western blot confirmed the inhibition of TGFβ canonical and non-canonical signaling pathways.

Conclusions:

• Inhibition of the TGFβ1-dependent SMAD3 signaling pathway effectively blocks the development of AV calcification in klotho knockout mice.
• These findings provide valuable insights into the signaling mechanisms underlying CAVD.
• Targeting TGFβ1-SMAD3 signaling presents a promising avenue for pharmacological intervention in CAVD.