Study of valve interstitial and endothelial cell sex differences and potential mineralocorticoid receptor antagonism benefits in chronic aortic regurgitation

• Autores: Mattie Garaikoetxea Zubillaga
• Directores de la Tesis: Natalia López Andrés (dir. tes.), Eva Jover (dir. tes.)
• Lectura: En la Universidad Pública de Navarra ( España ) en 2025
• Idioma: inglés
• Número de páginas: 110
• Programa de doctorado: Programa de Doctorado en Biotecnología por la Universidad Pública de Navarra
• Enlaces
  • Tesis en acceso abierto en: Academica-e
• Resumen

  • Background. Chronic aortic regurgitation (AR) is one of the most common heart valve diseases (HVD) of the aortic valve (AV), with an estimated prevalence of 1.6 % in the general population over 65 years old, and its three times more prevalent in men. There is currently a lack of pharmacological treatments that can delay or reverse chronic AR, being its surgical replacement or repair the only effective treatments. Little is known about its pathophysiology, often underscored because of the higher prevalence of aortic stenosis and a common misunderstanding of AR as an early stage of it. The two main cell populations of the heart valves are the valve interstitial cells (VICs) and the valve endothelial cells (VECs), which contribute to an excessive extracellular matrix (ECM) remodelling by VIC myofibroblast activation and VEC endothelial to mesenchymal transition (EndMT). Mineralocorticoid receptor (MR) involvement in HVD has been previously described, along with the benefits of MR antagonism (MRA) in cardiovascular diseases. Objectives. The present doctoral Thesis focuses on describing the cellular and molecular differences between sexes in AR, and the possible beneficial effects of the MRA treatment. Methods. AV tissues of a cohort of 144 patients diagnosed with AR by echocardiography, and human primary-cultured VIC and VEC were used in this Thesis. OMIC technologies including bulk transcriptomics on VICs and VECs and proteomic studies on cellular secretomes and whole AVs were conducted. Bioinformatic analyses with EnrichR and Ingenuity Pathway Analysis (IPA) were performed for transcriptome results interpretation. Validation studies using histology, immuno-cyto/histochemistry, ELISA, western blotting or qPCR were applied, as appropriate. Results. Transcriptomic analyses revealed that male VICs had a proinflammatory, profibrotic and proliferative profile, whereas VICs from women tend to have a higher lipidic metabolism. In accordance, Olink discovery experiments showed that VICs from men secreted more cytokines and inflammatory mediators. Conversely, isolated VECs tend to go through EndMT, resulting in highly heterogenous cell cultures that make specially challenging their analyses. Nonetheless, based on the donor’s sex only COL8A1 was found differentially expressed. Importantly, the MR was more expressed in male VICs, and its expression correlated positively with VIC activation and fibrotic markers, even in full AVs. The use of MRA in vitro decreased inflammatory and fibrotic molecules secretion in male VICs. A cohort subanalysis in MRA treated and non-treated patients showed that MRA-treated patients presented overall lower levels of proinflammatory and collagen molecules than non-MRA patients. Conclusions. Cellular and molecular sex-related mechanisms may drive AR and require specific drug choices to provide adequate personalized treatments. Fibroinflammatory cues and metabolism seem to be pivotal to the sex-specific contribution of the VICs in AR. Moreover, VECs seems to contribute to valvular ECM changes in AR through EndMT, despite the technical challenges reported in this Thesis. MR seems to mediate fibro-inflammatory phenotypes at the cellular and tissue levels in AR, thus arising as a possible treatment in the management of AR that could be easily regulated by MRAs already approved by reference health agencies.