Abstract 11649: Serum Adiponectin Levels Correlate With Atrial PPARγ and TGFβ1 mRNA Expression in Patients Receiving Cardiac Surgery: Involvement of PPARγ on Atrial Fibrotic Remodeling

Abstract

Introduction: The peroxisome proliferator-activated receptor gamma (PPAR γ) plays important roles in regulating processes related to fibrogenesis. On the other hand, adiponectin, a marker for PPARγ activity, is a hormone involved in maintaining energy homeostasis, and exerts anti-profibrotic effects in various organs. However, the roles of PPARγ and adiponectin on atrial fibrotic remodeling are still unknown. Hypothesis: We investigated the association of serum adiponectin levels and atrial gene expression of adiponectin, PPARγ and fibrosis-related genes in cardiovascular surgery patients including heart valve disease. Methods: Atrial mRNA expression levels including adiponectin and PPARγ were analyzed by real-time reverse transcription polymerase chain reaction (RT-PCR) in 59 cases (sinus rhythm (SR) 24 patients, atrial fibrillation (AF) 35 patients) in which left atrium (LA) tissues were removed from the appendage during surgery. The immunohistochemical studies were used to identify the protein expression. The serum levels of adiponectin were measured by ELISA. Results: The immunohistochemical staining showed the expression of adiponectin, PPARγ and PPARα. The significant correlations were observed among the mRNA expression levels of extracellular matrix (ECM) (COL1A1, COL3A1, fibronectin) and the fibrosis-related genes such as TGFβ1, TIMP1, MMP2, NOX2, CTGF and PDGFD attributed to the fibrosis of myocardium. The mRNA expression level of PPARγ, but not PPARα, positively correlated with that of the ECM and the fibrosis-related gene expression level. The mRNA expression level of adiponectin also positively correlated with that of ECM. Patients with AF had higher atrial expression level of adiponectin, PPARγ, COL1A1 and TGFβ than those with SR. Serum adiponectin levels significantly correlated with atrial mRNA expression level of PPARγ and TGFβ1. Patients with AF had serum higher levels of adiponectin than those with SR. Conclusions: Atrial PPARγ and adiponectin associate with atrial fibrotic remodeling in cardiovascular surgery patients. Serum adiponectin levels correlate with atrial PPARγ and TGFβ1 mRNA expression, and might have potential utility as a biomarker in atrial fibrotic remodeling.