Personne :
Le Quang, Khai

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Le Quang
Université Laval. Département de médecine
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  • Publication
    Carbonic anhydrase XII in valve interstitial cells promotes the regression of calcific aortic valve stenosis.
    (Academic Press Inc, Ltd., 2016-03-11) Lachance, Dominic.; Bouchareb, Rihab; Asselin, Jérémie; Boudreau, Denis; Marette, André; Boulanger, Marie-Chloé; Le Quang, Khai; Côté, Nancy.; Bossé, Yohan; Shayhidin, Elnur Elyar; Messaddeq, Younès; El Husseini, Diala; Mahmut, Ablajan; Pibarot, Philippe; Hadji, Fayez; Mathieu, Patrick
    Aims: Calcific aortic valve stenosis (CAVS) is the most common heart valve disease. In the present work we sought to determine the reversibility of mineralization in the aortic valve. Methods and results: By using in vitro analyses we found that valve interstitial cells (VICs) have the ability to resorb minerals. We documented that agonist of P2Y2 receptor (P2Y2R) promoted the expression of carbonic anhydrase XII (CAXII) at the cell membrane of VICs, whereby minerals are resorbed. P2Y2R-mediated mineral resorption was corroborated by using mouse VICs isolated from wild type and P2Y2R-/- mice. Measurements of extracellular pH (pHe) by using core–shell nanosensors revealed that P2Y2R-mediated CAXII export to the cell membrane led to an acidification of extracellular space, whereby minerals are resorbed. In vivo, we next treated LDLR-/-/ApoB100/100/IGF2 mice, which had developed CAVS under a high-fat/high-sucrose diet for 8 months, with 2-thioUTP (a P2Y2R agonist) or saline for the next 2 months. The administration of 2-thioUTP (2 mg/kg/day i.p.) reduced the mineral volume in the aortic valve measured with serial microCT analyses, which improved hemodynamics and reduced left ventricular hypertrophy (LVH). Examination of leaflets at necropsy confirmed a lower level of mineralization and fibrosis along with higher levels of CAXII in mice under 2-thioUTP. In another series of experiment, the administration of acetazolamide (a CA inhibitor) prevented the acidification of leaflets and the regression of CAVS induced by 2-thioUTP in LDLR-/-/ApoB100/100/IGF2 mice. Conclusion: P2Y2R-mediated expression of CAXII by VICs acidifies the extracellular space and promotes the regression of CAVS.
  • Publication
    Early development of calcific aortic valve disease and left ventricular hypertrophy in a mouse model of combined dyslipidemia and type 2 diabetes mellitus.
    (American Heart Association, 2014-08-14) Lachance, Dominic.; Bouchareb, Rihab; Kohen Avramoglu, Rita; Fournier, Dominique; Marette, André; Boulanger, Marie-Chloé; Le Quang, Khai; El Husseini, Diala; Fang, Xiang Ping; Pibarot, Philippe; Deshaies, Yves; Sweeney, Gary; Mathieu, Patrick; Laplante, Marc André
    Objective—This study aimed to determine the potential impact of type 2 diabetes mellitus on left ventricular dysfunction and the development of calcified aortic valve disease using a dyslipidemic mouse model prone to developing type 2 diabetes mellitus. Approach and Results—When compared with nondiabetic LDLr-/-/ApoB100/100, diabetic LDLr-/-/ApoB100/100/IGF-II mice exhibited similar dyslipidemia and obesity but developed type 2 diabetes mellitus when fed a high-fat/sucrose/cholesterol diet for 6 months. LDLr-/-/ApoB100/100/IGF-II mice showed left ventricular hypertrophy versus C57BL6 but not LDLr-/-/ ApoB100/100 mice. Transthoracic echocardiography revealed significant reductions in both left ventricular systolic fractional shortening and diastolic function in high-fat/sucrose/cholesterol fed LDLr-/-/ApoB100/100/IGF-II mice when compared with LDLr-/-/ApoB100/100. Importantly, we found that peak aortic jet velocity was significantly increased in LDLr-/-/ApoB100/100/ IGF-II mice versus LDLr-/-/ApoB100/100 animals on the high-fat/sucrose/cholesterol diet. Microtomography scans and Alizarin red staining indicated calcification in the aortic valves, whereas electron microscopy and energy dispersive x-ray spectroscopy further revealed mineralization of the aortic leaflets and the presence of inflammatory infiltrates in diabetic mice. Studies showed upregulation of hypertrophic genes (anp, bnp, b-mhc) in myocardial tissues and of osteogenic genes (spp1, bglap, runx2) in aortic tissues of diabetic mice. Conclusions—We have established the diabetes mellitus –prone LDLr-/-/ApoB100/100/IGF-II mouse as a new model of calcified aortic valve disease. Our results are consistent with the growing body of clinical evidence that the dysmetabolic state of type 2 diabetes mellitus contributes to early mineralization of the aortic valve and calcified aortic valve disease pathogenesis.