Lysyl oxidase-dependent extracellular matrix crosslinking modulates calcification in atherosclerosis and aortic valve disease

Abstract

Atherosclerosis; Cardiovascular calcification; Lysyl oxidase

Aterosclerosis; Calcificación cardiovascular; Lisil oxidasa

Aterosclerosi; Calcificació cardiovascular; Lisil oxidasa

Extracellular matrix (ECM) is an active player in cardiovascular calcification (CVC), a major public health issue with an unmet need for effective therapies. Lysyl oxidase (LOX) conditions ECM biomechanical properties; thus, we hypothesized that LOX might impact on mineral deposition in calcific aortic valve disease (CAVD) and atherosclerosis. LOX was upregulated in calcified valves from two cohorts of CAVD patients. Strong LOX immunostaining was detected surrounding calcified foci in calcified human valves and atherosclerotic lesions colocalizing with RUNX2 on valvular interstitial cells (VICs) or vascular smooth muscle cells (VSMCs). Both LOX secretion and organized collagen deposition were enhanced in calcifying VICs exposed to osteogenic media. β-aminopropionitrile (BAPN), an inhibitor of LOX, attenuated collagen deposition and calcification. VICs seeded onto decellularized matrices from BAPN-treated VICs calcified less than cells cultured onto control scaffolds; instead, VICs exposed to conditioned media from cells over-expressing LOX or cultured onto LOX-crosslinked matrices calcified more. Atherosclerosis was induced in WT and transgenic mice that overexpress LOX in VSMC (TgLOXVSMC) by AAV-PCSK9D374Y injection and high-fat feeding. In atherosclerosis-challenged TgLOXVSMC mice both atherosclerosis burden and calcification assessed by near-infrared fluorescence (NIRF) imaging were higher than in WT mice. These animals also exhibited larger calcified areas in atherosclerotic lesions from aortic arches and brachiocephalic arteries. Moreover, LOX transgenesis exacerbated plaque inflammation, and increased VSMC cellularity, the rate of RUNX2-positive cells and both connective tissue content and collagen cross-linking. Our findings highlight the relevance of LOX in CVC and postulate this enzyme as a potential therapeutic target for CVC.

We thank the technical support provided by Silvia Aguiló. This work was supported by the Spanish Ministerio de Ciencia e Innovación (RTI2018-094727-B-100 and PID2021-122509OB-I00 funded by MCIN/ AEI/10.13039/501100011033 and by “ERDF A way of making Europe”), Instituto de Salud Carlos III (ISCIII; Spain; PI21/01048), and Fundación Española de Arteriosclerosis (FEA-2022). C.B-S and L.P-U were supported by a FPU (Ministerio de Universidades; Spain), and PFIS (ISCIII) fellowships, respectively and N.L-A by a Miguel Servet contract (ISCIII). There is no financial or personal relationship with organizations that could potentially influence the described research.