Background: Stenotic aortic valves lesions differ according to patient’s sex: females reach similar hemodynamic severity of aortic stenosis (AS) with lower aortic valve calcification and higher valvular fibrosis than males. We previously demonstrated an overexpression of USP9X in females’ stenotic aortic valves compared to males’ ones. In this context, we aim to understand the role of USP9X in AS, according to patient’s sex.
METHODS AND RESULTS: We collected aortic valves from patients undergoing a surgical aortic valve replacement (15 males and 15 females) and from patients who underwent heart transplant (n=6) (Table 1). Ten of the diseased valves (5 males and 5 females) were digested to collect valvular interstitials cells (VICs) which were then cultured under fibrotic conditions during 14 days. We quantified the expression of USP9X, COL1, COL3, MMP2, RUNX2, ALPL and the accumulation of calcium using RTqPCR, western blot (WB), ELISA and immunohistochemistry (IHC) in explanted valves and in VICs. IHC results showed an overexpression of USP9X in stenotic aortic valves compared to non-stenotic aortic valves with a colocalization of USP9X and RUNX2 near calcifications. We also observed an overexpression of USP9X in females’ valves compared to males with RTqPCR and WB. In VICs grown in fibrotic conditions, we observed an overexpression of COL1 and COL3 in both males and females with a slight decrease of RUNX2 in males VICs. We identified an overexpression of USP9X with RTqPCR while a down-regulation with WB when VICs were grown in fibrotic conditions compared to control ones (Figure 1).
Conclusion: This study suggests that USP9X is involved in the accumulation of fibrosis and calcification observed in AS. In the first fibrotic phase of AS, expression of USP9X is inhibited while its transcription is increased, suggesting a negative feedback of USP9X in this stage. However, we observed an overexpression of USP9X near calcifications in stenotic aortic valves. The level of expression of USP9X might regulate the transition between fibrotic and fibrocalcific stages in AS, with sex-specific features.
