Disturbances in sphingolipid metabolism lead to biological function dysregulation in many diseases, but it has not been described in heart failure (HF). Sphingosine-1-phosphate (S1P) levels have not ever been measured in the myocardium. Therefore, we analyze the gene dysregulation of human cardiac tissue by mRNA-seq (n = 36) and ncRNA-seq (n = 50). We observed most major changes in the expression of genes belonging to de novo and salvage pathways, and the tight gene regulation by their miRNAs is largely dysregulated in HF. We verified using ELISA (n = 41) that ceramide and S1P accumulate in HF cardiac tissue, with an increase in the ceramide/S1P ratio of 57% in HF. Additionally, changes in left ventricular mass and diameters are directly related to CERS1 expression and inversely related to S1P levels. Altogether, we define changes in the main components of the sphingolipid metabolism pathways in HF, mainly de novo and salvage, which lead to an increase in ceramide and S1P in cardiac tissue, as well as an increase in the ceramide/S1P ratio in HF patients. Therapeutic gene modulation focused on restoring ceramide levels or reversing the ceramide/S1P ratio could be a potential therapy to be explored for HF patients.

Despite the reduction of cardiovascular events, including the risk of death, associated with sodium/glucose cotransporter 2 inhibitors (SGLT2i), their basic action remains unclear. Sodium/hydrogen exchanger (NHE) has been proposed as the mechanism of action, but there are controversies related to its function and expression in heart failure (HF). We hypothesized that sodium transported-related molecules could be altered in HF and modulated through SGLT2i. Transcriptome alterations in genes involved in sodium transport in HF were investigated in human heart samples by RNA-sequencing. NHE11 and NHE1 protein levels were determined by ELISA; the effect of empagliflozin on NHE11 and NHE1 mRNA levels in rats’ left ventricular tissues was studied through RT-qPCR. We highlighted the overexpression of SLC9C2 and SCL9A1 sodium transport genes and the increase of the proteins that encode them (NHE11 and NHE1). NHE11 levels were correlated with left ventricular diameters, so we studied the effect of SGLT2i on its expression, observing that NHE11 mRNA levels were reduced in treated rats. We showed alterations in several sodium transports and reinforced the importance of these channels in HF progression. We described upregulation in NHE11 and NHE1, but only NHE11 correlated with human cardiac dysfunction, and its levels were reduced after treatment with empagliflozin. These results propose NHE11 as a potential target of SGLT2i in cardiac tissue.

Background. Given the central role of sarcomeric dysfunction in cardiomyocyte biology and sarcomere alterations described in endomyocardial biopsies of transplant patients with rejection, we hypothesized that the serum expression levels of genes encoding sarcomeric proteins were altered in acute cellular rejection (ACR). The aim of this study is to identify altered sarcomere-related molecules in serum and to evaluate their diagnostic accuracy for detecting rejection episodes. Methods. Serum samples from transplant recipients undergoing routine endomyocardial biopsies were included in an RNA sequencing analysis (n = 40). Protein concentrations of alpha-cardiac actin were determined using a specific enzyme-linked immunoassay (n = 80). Results. We identified 17 sarcomeric genes differentially expressed in patients with clinically relevant rejection (grade ≥2R ACR). A receiver operating characteristic curve was done to assess their accuracy for ACR detection and found that 6 relevant actins, myosins, and other sarcomere-related genes showed great diagnostic capacity with an area under the curve (AUC) > 0.800. Specifically, the gene encoding alpha-cardiac actin (ACTC1) showed the best results (AUC = 1.000, P < 0.0001). We determine ACTC1 protein levels in a larger patient cohort, corroborating its overexpression and obtaining a significant diagnostic capacity for clinically relevant rejection (AUC = 0.702, P < 0.05). Conclusions. Sarcomeric alterations are reflected in peripheral blood of patients with allograft rejection. Because of their precision to detect ACR, we propose sarcomere ACTC1 serum expression levels as potential candidate for to be included in the development of molecular panel testing for noninvasive ACR detection.

Although the roles of telomeres and oxidative stress in ischaemic cardiomyopathy (ICM) are known, mechanisms of telomere homeostasis and their relationship with oxidative stress are incompletely understood. We performed two RNA-seq analyses (mRNA n = 23; ncRNA n = 30) and protein validation on left ventricles of explanted hearts from ICM and control subjects. We observed dysregulation of the shelterin and cohesin complexes, which was related to an increase in the response to cellular oxidative stress. Moreover, we found alterations at mRNA level in the mechanisms of telomeric DNA repair. Specifically, increased RAD51D mRNA levels were correlated with left ventricular diameters. RAD51D protein levels were unaltered, however, and were inversely corelated with the miR-103a-3p upregulation. We also observed the overexpression of lncRNAs (TERRA and GUARDIN) involved in telomere protection in response to stress and alterations in their regulatory molecules. Expression of the TERRA transcription factor ATF7 was correlated with superoxide dismutase 1 expression and left ventricular diameters. The levels of GUARDIN and its transcription factor FOSL2 were correlated with those of catalase. Therefore, we showed specific alterations in the mechanisms of telomeric DNA repair and protection, and these alterations are related to an increase in the response mechanisms to oxidative stress and cardiac dysfunction in ICM.