Rivaroxaban attenuates valvular inflammation and tissue remodeling in patients with severe aortic stenosis
Authors: Kopytek M , Zabczyk M , Undas A , Natorska J 
Published: October 2021

Abstract

Background
It has been demonstrated in a mouse model of atherosclerosis that non-vitamin K antagonist oral anticoagulants (NOACs) attenuate atherosclerotic plaque progression. However, it is not known whether NOACs can inhibit aortic stenosis (AS) progression.

Aims
To evaluate whether rivaroxaban at therapeutic concentrations can impair valvular inflammation and valve remodeling in patients with severe AS.

Methods
We recruited 38 patients with isolated severe AS aged 68±8 years (mean gradient 54 mmHg, max gradient 86 mmHg), including 18 individuals with AS and atrial fibrillation taking rivaroxaban (20 mg/daily for at least 3 years). Stenotic aortic valves were obtained during valve replacement surgery. Valvular expression of NFκB, matrix metalloproteinase 9 (MMP-9) and bone morphogenetic protein 2 (BMP-2) was evaluated by immunostaining. Primary cultures of valve interstitial cells (VICs) obtained from stenotic aortic valves were stimulated with TNF-α to induce inflammation. In parallel, VICs were cultured with TNF-α and rivaroxaban at therapeutic concentrations (1 and 10 μg/ml, corresponding to about 2.5 mg and 25 mg daily in vivo). The expression of NFκB, interleukin 1β (IL-1β), reactive oxygen species (ROS), MMP-9 and BMP-2 in VICs was assessed. The control VICs were cultured without any additives. All VICs were cultured for 72 hours and experiments were repeated 3 times. The fluorescence intensity was computed as the ratio (%) of positively and negatively stained areas.

Results
We observed decreased valvular expression of NFκB (−54%), MMP-9 (−32%) and BMP-2 (−23%) in patients taking rivaroxaban compared to those without such treatment. TNF-α stimulation up-regulated expression of NFκB, IL-1β and ROS (+58%; +34%; +38%; all p&lt;0.01) accompanied by higher expression of MMP-9 and BMP-2 (+49% for MMP-9 and +32% for BMP-2; both p&lt;0.01), when compared to control cells. Rivaroxaban at a concentration of 10 μg/ml decreased the expression of ROS (−31%, p&lt;0.01), inflammatory markers (NFκB −47% and IL-1β −22%, both p&lt;0.01) and MMP-9 (−39%, p&lt;0.01) compared to VICs cultured without rivaroxaban. Similarly, BMP-2 expression was down regulated after 10 μg/ml of rivaroxaban (−26%, p&lt;0.01). Even low dose of rivaroxaban decreased VICs expression of NFκB, IL-1β and ROS by 38%, 18% and 25%, respectively (all p&lt;0.01) as compared to cells stimulated with TNF-α only. Comparable effect was observed for MMP-9 and BMP-2 expression (−33%; −22%; both p&lt;0.01).

Conclusions
Rivaroxaban can decrease valvular inflammation and its remodelling and significantly inhibits inflammation, extracellular matrix activity and calcification of VICs. Our study suggests that NOACs, even at a low dose, could slow the rate of AS progression, at least in AS patients with mild-to-moderate AS and indications for anticoagulant therapy. Clinical relevance of these findings requires further studies.

Funding Acknowledgement
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Science Centre (NCN)