Circulating Sphingosine-1-Phosphate as A Non-Invasive Biomarker of Heart Transplant Rejection

Estefanía Tarazón,Manuel Portolés,Esther Roselló-Lletí,Luis Martínez-Dolz,José Ramón González-Juanatey,Francisca Lago,María García Manzanares,Marta Roca,Elena Sánchez-Lacuesta,Carolina Gil-Cayuela

doi:10.1038/s41598-019-50413-8

Abstract

Accumulating evidence has confirmed that the expression of sarcoplasmic reticulum calcium ATPase 2a (SERCA2a) is downregulated in heart failure and cardiac allograft rejection. Although many SERCA2a-related genes and proteins involved in the regulation of myocardial Ca2+ fluxes have been explored, its related metabolites remain poorly studied. Our main objective was to identify circulating SERCA2a-related metabolites altered in cardiac allograft rejection and to determine whether these could serve as non-invasive biomarkers. Sixty plasma samples from adult heart transplant were included in a metabolomic analysis. Sphingosine-1 phosphate (S1P), metabolite closely related with SERCA, were increased in patients with cardiac rejection (p < 0.0001). S1P discriminated between patients with and without rejection: normal grafts vs. all rejecting grafts (AUC = 0.911, p < 0.0001), normal grafts vs. Grade 1 R (AUC = 0.819, p < 0.01), Grade 2 R (AUC = 0.911, p < 0.0001), Grade 3 R (AUC = 0.996, p < 0.0001). In addition, we found changes in key enzymes and receptors of S1P pathway analysed on explanted hearts from heart failure patients. This preliminary study reveals that circulating S1P determination could be a novel approach to detect cardiac rejection, showing a robust capability for detection that improves gradually with the severity of rejection. These alterations could be relevant to better understand the involvement of calcium regulation on the pathophysiology of rejection.

Highlights

It is involved in cardiac allograft rejection; we previously demonstrated that SERCA2a serum levels change during heart rejection[10]
We previously observed partial translocation of nitric oxide by nitric oxide synthase 1 (NOS1) to the sarcolemma in ischemic hearts[19] and that the upregulation of cardiac NOS1 is not accompanied by increased NOS1 activity in dilated cardiomyopathy[20]
From the non-rejection group vs. Grades 2 R and 3 R discriminant analysis, we built a variance importance in projection (VIP) plot, summarizing the contribution that each variable makes to the discriminant model

Summary

Introduction

It is involved in cardiac allograft rejection; we previously demonstrated that SERCA2a serum levels change during heart rejection[10]. We previously observed partial translocation of nitric oxide by nitric oxide synthase 1 (NOS1) to the sarcolemma in ischemic hearts[19] and that the upregulation of cardiac NOS1 is not accompanied by increased NOS1 activity in dilated cardiomyopathy[20]. This SERCA2a-related protein may be significant in the pathophysiology of human ischemic and dilated heart disease with a preservative role in maintaining myocardial homeostasis. We analysed the S1P pathway through the mRNA determination of the key enzymes in the S1P generation and breakdown and its receptors on explanted hearts from patients with heart failure

Methods

Results

Conclusion