Impact of glucose fluctuation on the paracrine secretome profile of human epicardial adipocyte

Abstract

Abstract Background Glucose fluctuations (GF) is known to be the significant factor related to poor cardiovascular outcome in the diabetic patients. We investigated the potential impact of GF on paracrine effect of human epicardial adipocyte on cardiomyocyte. Methods Human EAT biopsies obtained during surgery and isolated preadipocyte/adipocytes were used to evaluate the direct impact of GF on the adipocytes. Matured adipocytes were exposed to the media containing normal glucose (100 mg/dl, NG), high glucose (300 mg/dl, HG), or high-low glucose (75-300 mg/dl, GF) for 1 week. Transcriptomic profiling of the cultured matured adipocyte was performed using microarray analysis. The impact of GF on the paracrine effect of adipocyte was evaluated using a co-culture with human iPS-derived atrial cardiomyocytes and the adipocytes. Clinical association study verified the validity of the findings. Results GF for 1 week altered the expression of 595 differentially expressed genes (up-regulated or down-regulated) with an effect size of >50% or `−50% and a significant statistical difference (P < 0.05) in human epicardial adipocytes, while the continuous HG for 1 week altered the expression of only 182 differentially expressed genes. Of the genes affected by GF, top 3 most affected genes included IL1β, IL33, IL8. Regarding the other major pro-inflammatory cytokines, IL1α, CCL2 and IL6 were also significantly increased in the adipocyte treated with GF, however these were not increased in the adipocyte treated with HG. Co-culture of human iPS cell-derived atrial cardiomyocytes and adipocytes treated with NG, HG and GF revealed that GF-treated adipocyte strikingly increased oxidative stress in the cardiomyocyte through the paracrine effect. In the real-world clinical association study, IL1β mRNA expression in human epicardial adipose tissue showed significant positive correlation with the severity of GF during hospitalization and oxidative stress in the left atrial myocardium. Conclusions GF adversely affect the paracrine secretome profile of human epicardial adipocyte. IL1β may be a critical epicardial adipocyte-derived adipokine that is enhanced by GF.