Heart failure (HF) is a disease related to bioenergetic mitochondrial abnormalities. However, the whole status of molecules involved in the oxidative phosphorylation system (OXPHOS) is unknown. Therefore, we analyzed the OXPHOS transcriptome of human cardiac tissue by RNA-seq analyses (mRNA n = 36; ncRNA n = 30) in HF patients (ischemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM)) and control subjects. We detected 28 altered genes in these patients, highlighting greater deregulation in ICM. Specifically, we found a general overexpression of complex V (ATP synthase) elements, among them, ATP5I (ICM, FC = 2.04; p < 0.01), ATP5MJ (ICM, FC = 1.33, p < 0.05), and ATP5IF1 (ICM, FC = 1.81; p < 0.001), which presented a significant correlation with established echocardiographic parameters of cardiac remodeling and ventricular function as follows: left ventricular end-systolic (p < 0.01) and end-diastolic (p < 0.01) diameters, and ejection fraction (p < 0.05). We also detected an increase in ATP5IF1 protein levels (ICM, FC = 1.75; p < 0.01) and alterations in the microRNA expression levels of miR-208b-3p (ICM, FC = −1.44, p < 0.001), miR-483-3p (ICM, FC = 1.37, p < 0.01), regulators of ATP5I. Therefore, we observed the deregulation of the OXPHOS transcriptome in ICM patients, highlighting the overexpression of complex V and its relationship with cardiac remodeling and function.

Heart failure (HF) is associated with global changes in gene expression. Alternative mRNA splicing (AS) is a key regulatory mechanism underlying these changes. However, the whole status of molecules involved in the splicing process in human HF is unknown. Therefore, we analysed the spliceosome transcriptome in cardiac tissue (n = 36) from control subjects and HF patients (with ischaemic (ICM) and dilated (DCM) cardiomyopathies) using RNA-seq. We found greater deregulation of spliceosome machinery in ICM. Specifically, we showed widespread upregulation of the E and C complex components, highlighting an increase in SNRPD2 (FC = 1.35, p < 0.05) and DHX35 (FC = 1.34, p < 0.001) mRNA levels. In contrast, we observed generalised downregulation of the A complex and cardiac-specific AS factors, such as the multifunctional protein PCBP2 (FC = −1.29, p < 0.001) and the RNA binding proteins QKI (FC = −1.35, p < 0.01). In addition, we found a relationship between SNPRD2 (an E complex component) and the left ventricular mass index in ICM patients (r = 0.779; p < 0.01). On the other hand, we observed the specific underexpression of DDX46 (FC = −1.29), RBM17 (FC = −1.33), SDE2 (FC = −1.35) and RBFOX1 (FC = −1.33), p < 0.05, in DCM patients. Therefore, these aetiology-related alterations may indicate the differential involvement of the splicing process in the development of ICM and DCM.

Although the potential role of carbohydrate antigen 125 (CA125) in acute cellular rejection (ACR) has been explored, its role in antibody-mediated rejection (AMR) remains unclear. Since CA125 is associated with inflammation and congestion, we hypothesized that CA125 could reflect key processes in AMR and complement the existing diagnostic methods. We analyzed 491 serum samples from heart transplant recipients undergoing first-year routine endomyocardial biopsies (EMBs). The results of EMB were classified as no-rejection, ACR, or AMR. CA125 levels were measured using a chemiluminescent immunoassay. CA125 concentrations were significantly higher in the AMR group (median 41 [IQR 26–78] U/mL) than in the no-rejection group (median 17 [IQR 11–27] U/mL; p < 0.01), regardless of post-transplantation time. In contrast, no significant differences were observed between the ACR and no-rejection groups (p = 0.124). Receiver operating characteristic analysis demonstrated strong diagnostic performance of CA125 for AMR (area under the curve = 0.821; p < 0.001). CA125 was an independent predictor of AMR (odds ratio, 5.04; p < 0.01). Our results demonstrated that elevated circulating CA125 levels are associated with AMR and exhibit promising diagnostic performance after heart transplantation, highlighting their potential as a non-invasive biomarker. This is further supported by the wide availability, standardization, and reproducibility of CA125 measurements in clinical practice.

Background/Objectives: Cardiac allograft fibrosis is an important limiting factor for long-term graft survival. However, the fibrotic process operating in patients with acute cellular rejection (ACR) remains unclear. We aimed to identify altered serum mRNAs related to cardiac fibrosis in patients with ACR and to evaluate their diagnostic accuracy in detecting rejection episodes. Methods: We included 40 serum samples from recipients of transplants undergoing routine endomyocardial biopsies. Results: Several altered mRNAs associated with fibrosis were detected in patients with ACR. Specifically, the activators of fibroblasts and myofibroblasts (TNS1, FAP and ACTA2), TGF-β signaling (TGFBR1 and JAK1) and WNT signaling (WNT7A and WLS) pathways were significantly different when we compared grade ≥ 2R ACR and/or grade 1R ACR groups with the nonrejection group. Furthermore, TNS1 and WLS presented an area under the curve value > 0.90 for identifying patients with moderate and severe grades of cardiac rejection. Conclusions: In conclusion, we found alterations in the relative abundance of circulating activators of fibroblasts and myofibroblasts, such as FAP or ACTA2, as well as in major profibrotic pathways, including TGF-β and WNT signaling, especially in clinically relevant cardiac rejection. These findings may contribute to improving the surveillance of patients with cardiac transplant and provide new therapeutic strategies for targeting fibrosis process activation.