OxLDL-derived lysophosphatidic acid promotes the progression of aortic valve stenosis through a LPAR1-RhoA-NF-κB pathway.

Aims: Oxidatively modified lipoproteins may promote the development/progression of calcific aortic valve stenosis (CAVS). Oxidative transformation of low-density lipoprotein (OxLDL) generates lysophosphatidic acid (LPA), a lipid mediator that accumulates in mineralized aortic valves. LPA activates at least six different G protein-coupled receptors, which may play a role in the pathophysiology of CAVS. We hypothesized that LPA derived from OxLDL may promote a NF-κB signature that drives osteogenesis in the aortic valve.

Methods and results: The role of OxLDL-LPA was examined in isolated valve interstitial cells (VICs) and the molecular pathway was validated in human explanted aortic valves and in a mouse model of CAVS. We found that OxLDL-LPA promoted the mineralization and osteogenic transition of VICs through LPAR1 and the activation of a RhoA-NF-κB pathway. Specifically, we identified that RhoA/ROCK activated IκB kinase alpha, which promoted the phosphorylation of p65 on serine 536 (p65 pS536). p65 pS536 was recruited to the BMP2 promoter and directed an osteogenic program not responsive to the control exerted by the inhibitor of kappa B. In LDLR-/-/ApoB100/100/IGFII transgenic mice (IGFII), which develop CAVS under a high-fat and high-sucrose diet the administration of Ki16425, a Lpar1 blocker, reduced by three-fold the progression rate of CAVS and also decreased the osteogenic activity as measured with a near-infrared fluorescent probe that recognizes hydroxyapatite of calcium.

Conclusions: OxLDL-LPA promotes an osteogenic program in the aortic valve through a LPAR1-RhoA/ROCK-p65 pS536 pathway. LPAR1 may represent a suitable target to prevent the progression of CAVS.