P2Y2 receptor represses IL-6 expression by valve interstitial cells through Akt: Implication for calcific aortic valve disease

• Published in: Journal of molecular and cellular cardiology Vol. 72; pp. 146 - 156
• Main Authors: El Husseini, Diala, Boulanger, Marie-Chloé, Mahmut, Ablajan, Bouchareb, Rihab, Laflamme, Marie-Hélène, Fournier, Dominique, Pibarot, Philippe, Bossé, Yohan, Mathieu, Patrick
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.07.2014
• Subjects: Animals; Aortic stenosis; Aortic Valve - drug effects; Aortic Valve - metabolism; Aortic Valve - pathology; Aortic Valve Stenosis - chemically induced; Aortic Valve Stenosis - genetics; Aortic Valve Stenosis - metabolism; Aortic Valve Stenosis - pathology; Calcific aortic stenosis; Calcific aortic valve disease; Calcinosis - chemically induced; Calcinosis - genetics; Calcinosis - metabolism; Calcinosis - pathology; Cardiovascular; Cells, Cultured; Culture Media - chemistry; Culture Media - pharmacology; Gene Expression Profiling; Gene Expression Regulation; Humans; IL-6; Interleukin-6 - antagonists & inhibitors; Interleukin-6 - genetics; Interleukin-6 - metabolism; Mice; Mice, Knockout; NF-kappa B; NF-kappa B - genetics; NF-kappa B - metabolism; P2Y2 receptor; Phosphates - pharmacology; Phosphatidylinositol 3-Kinases - genetics; Phosphatidylinositol 3-Kinases - metabolism; Proto-Oncogene Proteins c-akt - genetics; Proto-Oncogene Proteins c-akt - metabolism; Receptors, Purinergic P2Y2 - genetics; Receptors, Purinergic P2Y2 - metabolism; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; Signal Transduction; Aortic stenosis; Calcific aortic stenosis; P2Y2 receptor; NF-kappa B; Calcific aortic valve disease; IL-6
• ISSN: 0022-2828; 1095-8584
• DOI: 10.1016/j.yjmcc.2014.02.014

Abstract Calcific aortic valve disease (CAVD) is a disorder characterized by an abnormal mineralization, which may have intricate links with inflammation. Interleukin-6 (IL-6) and its cognate cytokines are widely expressed and exert pleiotropic effects on different tissues. In this study, we examined the expression of the IL-6 family of cytokines in human CAVD by using a transcriptomic approach and we performed in-depth functional assays with valve interstitial cells (VICs) to unravel the process regulating IL-6 expression and its role during the mineralization of the aortic valve. We documented by both microarray and q-PCR analyses an elevated expression of IL-6 in human CAVD, which was correlated with the remodeling process. IL-6 was highly expressed by VICs. We found that following treatment with a phosphate-containing medium the level of IL-6 expressed by VICs increased by several-fold. Phosphate-induced expression of IL-6 relied on reduced PI3K/Akt signaling downstream of the P2Y2 receptor (P2Y2R). In this regard, we found by using transfection experiments that Akt-1 is a negative regulator of the NF-κB pathway. In addition, by using a siRNA targeting IL-6 we found that phosphate-induced mineralization was largely dependent on IL-6 expression. A transfection of Akt-1 rescued the hypermineralizing phenotype of P2Y2R−/− mouse VICS (MVICs). Hence, we documented a novel mechanism whereby P2Y2R and Akt modulate the NF-κB pathway and its downstream target IL-6, which is a strong promoter of the mineralization of VICs.