Faculty Bibliography

Cardiac complications such as electrical abnormalities including conduction delays and arrhythmias are the main cause of death in individuals with Myotonic Dystrophy type 1 (DM1). We developed a disease model using iPSC-derived cardiomyocytes (iPSC-CMs) from a healthy individual and two DM1 patients with different CTG repeats lengths and clinical history (DM1-1300 and DM1-300). We confirmed the presence of toxic RNA foci and mis-spliced MBNL1/2 transcripts in DM1 iPSC-CMs. In DM1-1300, we identified a switch in the cardiac sodium channel SCN5A from the adult to the neonatal isoform. The down-regulation of adult SCN5A isoforms is consistent with a shift in the sodium current activation to depolarized potentials observed in DM1-1300. L-type calcium current density was higher in iPSC-CMs from DM1-1300, which is correlated with the overexpression of the Ca_V1.2 transcript and proteins. Importantly, I_Na and I_CaL dysfunctions resulted in prolonged action potentials duration, slower velocities, and decreased overshoots. Optical mapping analysis revealed a slower conduction velocity in DM1-1300 iPSC-CM monolayers. In conclusion, our data revealed two distinct ions channels perturbations in DM1 iPSC-CM from the patient with cardiac dysfunction, one affecting Na⁺ channels and one affecting Ca²⁺ channels. Both have an impact on cardiac APs and ultimately on heart conduction.

Higher levels of nitrated lipoproteins (NT-HDL and NT-LDL) were found in blood and atherosclerotic plaques of patients with coronary artery disease. We aimed to examine the relationship between plasma NT-HDL and NT-LDL and diabetic vascular dysfunction. The study included 125 African-American patients with T2DM. NT-HDL and NT-LDL were quantified by ELISA. Microvascular function was assessed by vascular reactivity index (VRI). Large artery stiffness was assessed by carotid-femoral pulse wave velocity (PWV). Carotid intima-media thickness (CIMT) was assessed by B-mode ultrasound imaging. In univariate analysis, NT-HDL was associated with VRI in total population and in patients with HbA1c more than or equal to 7.0 percent (beta= -0.178, p= 0.034; beta = -0.265, p= 0.042; respectively). In contrast, NT-LDL was associated with CIMT in total population and in patients with HbA1c more than 7.0 percent (beta = -0.205, p= 0.022; beta = -0.244, p= 0.042; respectively). Multivariable-adjusted regression analysis demonstrated that NT-HDL independently predicted VRI outcome in total population and in well-controlled patients (beta = -0.282, p= 0.014; beta = -0.400, p= 0.035, respectively). These results suggest that NT-HDL could be used as marker to identify diabetic patients at risk of developing early microvascular complications.

Numerous commonly prescribed drugs, including antiarrhythmics, antihistamines, and antibiotics, carry a proarrhythmic risk and may induce dangerous arrhythmias, including the potentially fatal Torsades de Pointes. For this reason, cardiotoxicity testing has become essential in drug development and a required step in the approval of any medication for use in humans. Blockade of the hERG K⁺ channel and the consequent prolongation of the QT interval on the ECG have been considered the gold standard to predict the arrhythmogenic risk of drugs. In recent years, however, preclinical safety pharmacology has begun to adopt a more integrative approach that incorporates mathematical modeling and considers the effects of drugs on multiple ion channels. Despite these advances, early stage drug screening research only evaluates QT prolongation in experimental and computational models that represent healthy individuals. We suggest here that integrating disease modeling with cardiotoxicity testing can improve drug risk stratification by predicting how disease processes and additional comorbidities may influence the risks posed by specific drugs. In particular, chronic systemic inflammation, a condition associated with many diseases, affects heart function and can exacerbate medications' cardiotoxic effects. We discuss emerging research implicating the role of inflammation in cardiac electrophysiology, and we offer a perspective on how in silico modeling of inflammation may lead to improved evaluation of the proarrhythmic risk of drugs at their early stage of development.

Autoimmunity is increasingly recognized as a novel pathogenic mechanism for cardiac arrhythmias. Several arrhythmogenic autoantibodies have been identified, cross-reacting with different types of surface proteins critically involved in the cardiomyocyte electrophysiology, primarily ion channels (autoimmune cardiac channelopathies). Specifically, some of these autoantibodies can prolong the action potential duration leading to acquired long-QT syndrome (LQTS), a condition known to increase the risk of life-threatening ventricular arrhythmias, particularly Torsades de Pointes (TdP). The most investigated form of autoimmune LQTS is associated with the presence of circulating anti-Ro/SSA-antibodies, frequently found in patients with autoimmune diseases (AD), but also in a significant proportion of apparently healthy subjects of the general population. Accumulating evidence indicates that anti-Ro/SSA-antibodies can markedly delay the ventricular repolarization via a direct inhibitory cross-reaction with the extracellular pore region of the human-ether-a-go-go-related (hERG) potassium channel, resulting in a higher propensity for anti-Ro/SSA-positive subjects to develop LQTS and ventricular arrhythmias/TdP. Recent population data demonstrate that the risk of LQTS in subjects with circulating anti-Ro/SSA antibodies is significantly increased independent of a history of overt AD, intriguingly suggesting that these autoantibodies may silently contribute to a number of cases of ventricular arrhythmias and cardiac arrest in the general population. In this review, we highlight the current knowledge in this topic providing complementary basic, clinical and population health perspectives.

The COVID-19 pandemic has highlighted race-based health disparities and structural racism in the United States. Enhancing the training of early-career academic and health scientists from underrepresented minority groups (URM) is critical to reduce disparities affecting underserved population groups. A dedicated training program that has been proven to support URM can facilitate career development for junior faculty during the pandemic. This critical support ensures the retention of talented, racially diverse junior faculty who are poised to mitigate structural racism, rather than perpetuate it. We describe how the Cardiovascular Disease Programs to Increase Diversity Among Individuals Engaged in Health-Related Research (PRIDE-CVD) summer institute successfully transitioned from a face-to-face format to a virtual format during the COVID-19 pandemic. As a result, early-career faculty continued to receive the PRIDE-CVD training on research methodology, grantsmanship, career development, and CVD health disparities, especially as related to the pandemic. In addition, the virtual format facilitated networking, promoted mental wellness, and allowed continual mentorship. Collectively, the program provided timely and relevant career development in the COVID-19 era and helped participants navigate the psychosocial challenges of being a URM in cardiovascular health research.

Background/UNASSIGNED:Clinical experience showed that the majority of Torsade de Pointes (TdP) ventricular tachyarrhythmia (VT) in patients with long QT syndrome (LQTS) are self-terminating (ST), but the few that are non-self-terminating (NST) are potentially fatal. A paramount issue in clinical arrhythmology is to understand the electrophysiological mechanism of ST vs. NST TdP VT. Methods/UNASSIGNED: Results/UNASSIGNED: Conclusions/UNASSIGNED:

Background - During acute infections the risk of malignant ventricular arrhythmias (VA) is increased, partly because of a higher propensity to develop QTc prolongation. Although it is generally believed that QTc changes almost exclusively result from concomitant treatment with QT-prolonging antimicrobials, direct effects of inflammatory cytokines on ventricular repolarization are increasingly recognized. We hypothesized that systemic inflammation per se can significantly prolong QTc during acute infections, via cytokine-mediated changes in K⁺-channels expression. Methods - We evaluated: (1) the frequency of QTc prolongation, and its association with inflammatory markers, in patients with different types of acute infections, during active disease and remission; (2) the prevalence of acute infections in a cohort of consecutive patients with Torsades de Pointes (TdP); (3) the relationship between K⁺-channels mRNA levels in ventricles and peripheral blood mononuclear cells (PBMC), and their changes in patients with acute infection over time. Results - In patients with acute infections, regardless of concomitant QT-prolonging antimicrobial treatments, QTc was significantly prolonged, but rapidly normalized in parallel to C-reactive protein (CRP) and cytokine levels reduction. Consistently in the TdP cohort, concomitant acute infections were highly prevalent (30%), despite only a minority (25%) of these cases were treated with QT-prolonging antimicrobials. KCNJ2 K⁺-channel expression in PBMC, which strongly correlated to that in ventricles, inversely associated to CRP and interleukin-1 changes in acute infection patients. Conclusions - During acute infections, systemic inflammation rapidly induces cytokine-mediated ventricular electrical remodelling and significant QTc prolongation, regardless concomitant antimicrobial therapy. Although transient, these changes may significantly increase the risk of life-threatening VA in these patients. It is timely and warranted to transpose these findings to the current coronavirus disease-19 pandemic (COVID-19), in which both increased amounts of circulating cytokines and cardiac arrhythmias are demonstrated along with a frequent concomitant treatment with several QT-prolonging drugs.