Esther Roselló-Lletí

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.

Background: Idiopathic dilated cardiomyopathy (iDCM) is a multifactorial disease with a complex pathogenesis involving diverse molecular mechanisms. Among these, epigenetic mechanisms, including both DNA methylation and microRNAs (miRNAs)-mediated regulation, play an important role in determining the disease phenotype. However, the interplay between the DNA methylome and the miRNA transcriptome in iDCM remains largely unexplored. Methods: We conducted a cross-cohort multiomic integrative analysis of left ventricular (LV) tissue samples from iDCM patients and control (CNT) donors. DNA methylation profiling was performed using the Infinium MethylationEPIC BeadChip, whereas ncRNA-seq was used to assess transcriptomic changes. Results: We identified a subset of three miRNAs exhibiting both differential methylation in their promoter regions and differential expression in their primary and mature forms. Notably, the miRNA hsa-miR-433-3p ( r = 0.671, p < 0.01), which is involved in fibrotic pathways, appear to be significantly correlated with the left ventricular ejection fraction (LVEF), an established echocardiographic marker of cardiac function. Conclusions: This study enhances our understanding of the epigenetic mechanisms shaping the miRNA transcriptomic landscape in iDCM, suggesting potential roles for these miRNAs in cardiac dysfunction and myocardial fibrosis.

The Golgi apparatus (GA) plays a main role in the protein secretory pathway. Previously, we described a greater GA vesicle density in patients with dilated cardiomyopathy (DCM), as well as an increase in natriuretic peptide (NP) levels inside these vesicles. GA fragmentation could increase the rate of protein transport; for this reason, we aimed to delve deeper into these GA vesicle density alterations by studying the expression of genes related to GA architecture in DCM and its relationship with NP levels. We performed RNA-seq analysis on explanted hearts from DCM patients (n = 13) and control (CNT) individuals (n = 10). We detected alterations in molecules related to the structure and positioning of GA, highlighting the decrease in GM130 levels and increase in the p-GM130/GM130 ratio (p < 0.05) observed via Western blotting (DCM, n = 23; CNT, n = 7) and their correlation with NT-proBNP levels (r = − 0.473, p < 0.05; r = 0.455, p < 0.05; respectively). We also observed an upregulation of genes involved in anterograde transport and a downregulation of genes involved in retrograde transport. Moreover, we visualized GA fragmentation in doxorubicin-induced DCM in AC16 cells via immunofluorescence (70.2% of the cells had fragmented GA, p < 0.05) and corroborated the downregulation of GOLGA2 and the increase in NP levels observed in human tissue. Our results revealed dysregulation of genes that maintain GA structure, suggesting that GA fragmentation occurs in DCM patients. Therefore, the imbalance between anterograde and retrograde transport could also contribute to this situation and to increased formation of transport vesicles.

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.

Long non-coding RNAs (lncRNAs) are closely implicated in biological processes and diseases with high inflammatory components. These molecules exhibit significant temporal and tissue specificity. However, the expression and function of lncRNAs have not been studied in patients after heart transplantation. Thus, we aimed to identify circulating lncRNAs in these patients and evaluate their diagnostic capacity as potential biomarkers for the non-invasive detection of acute cellular rejection (ACR). For them, we performed a transcriptomic study based on ncRNA-seq technology to detect lncRNAs in serum samples, matched to routine endomyocardial biopsies, from patients without rejection episode (0R, n = 12) and with mild (1R, n = 16) or moderate-severe (≥ 2R, n = 12) ACR. We identified 11,062 circulating lncRNAs in the serum of patients after heart transplantation. Moreover, 6 lncRNAs showed statistically significant expression when the different ACR grades were compared. Among them, AC008105.3, AC006525.1, AC011455.8, AL359220.1, and AC025279.1 had relevant diagnostic capacity for detection of ≥ 2R (AUC of 0.850 to 1.000) and 1R (AUC of 0.750 to 0.854) grades, along with high specificity and positive predictive values (≥ 83%). In addition, AL359220.1 and AC025279.1 were independent predictors for the presence of moderate-severe ACR (odds ratio = 31.132, p < 0.01 and C statistic = 0.939, p < 0.0001; odds ratio = 18.693, p < 0.05 and C statistic = 0.902, p < 0.001; respectively). In conclusion, we describe, for the first time, circulating lncRNAs after heart transplantation as potential candidates for non-invasive detection of ACR. AL359220.1 and AC025279.1 showed excellent diagnostic capability correlating with the severity episode and were strong independent predictors of rejection.

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.