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

Mrinmay Chakrabarti; Aniket Bhattacharya; Mengistu G Gebere; John Johnson; Zeeshan A Ayub; Ioulia Chatzistamou; Narendra R Vyavahare; Mohamad Azhar

doi:10.3389/fcvm.2022.770065

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

Front Cardiovasc Med. 2022 Jul 19:9:770065. doi: 10.3389/fcvm.2022.770065. eCollection 2022.

Authors

Mrinmay Chakrabarti¹, Aniket Bhattacharya^{1

2}, Mengistu G Gebere¹, John Johnson¹, Zeeshan A Ayub¹, Ioulia Chatzistamou³, Narendra R Vyavahare⁴, Mohamad Azhar^{1

5}

Affiliations

¹ Department of Cell Biology and Anatomy, School of Medicine, University of South Carolina, Columbia, SC, United States.
² Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ, United States.
³ Department of Pathology, Microbiology, and Immunology, School of Medicine, University of South Carolina, Columbia, SC, United States.
⁴ Biomedical Engineering, Clemson University, Clemson, SC, United States.
⁵ William Jennings Bryan Dorn VA Medical Center, Columbia, SC, United States.

Abstract

Aims: Calcific aortic valve disease (CAVD) is a progressive heart disease that is particularly prevalent in elderly patients. The current treatment of CAVD is surgical valve replacement, but this is not a permanent solution, and it is very challenging for elderly patients. Thus, a pharmacological intervention for CAVD may be beneficial. In this study, we intended to rescue aortic valve (AV) calcification through inhibition of TGFβ1 and SMAD3 signaling pathways.

Methods and results: The klotho gene, which was discovered as an aging-suppressor gene, has been observed to play a crucial role in AV calcification. The klotho knockout (Kl ^-/-) mice have shorter life span (8-12 weeks) and develop severe AV calcification. Here, we showed that increased TGFβ1 and TGFβ-dependent SMAD3 signaling were associated with AV calcification in Kl ^-/- mice. Next, we generated Tgfb1- and Smad3-haploinsufficient Kl ^-/- mice to determine the contribution of TGFβ1 and SMAD3 to the AV calcification in Kl ^-/- mice. The histological and morphometric evaluation suggested a significant reduction of AV calcification in Kl ^-/-; Tgfb1 ^± mice compared to Kl ^-/- mice. Smad3 heterozygous deletion was observed to be more potent in reducing AV calcification in Kl ^-/- mice compared to the Kl ^-/-; Tgfb1 ^± mice. We observed significant inhibition of Tgfb1, Pai1, Bmp2, Alk2, Spp1, and Runx2 mRNA expression in Kl ^-/-; Tgfb1 ^± and Kl ^-/-; Smad3 ^± mice compared to Kl ^-/- mice. Western blot analysis confirmed that the inhibition of TGFβ canonical and non-canonical signaling pathways were associated with the rescue of AV calcification of both Kl ^-/-; Tgfb1 ^± and Kl ^-/-; Smad3 ^± mice.

Conclusion: Overall, inhibition of the TGFβ1-dependent SMAD3 signaling pathway significantly blocks the development of AV calcification in Kl ^-/- mice. This information is useful in understanding the signaling mechanisms involved in CAVD.

Keywords: CAVD (calcific aortic valve disease); Klotho; Smad3; Tgfb = transforming growth factor beta; aortic valve calcification.