Downregulation of myogenic microRNAs in sub-chronic but not in sub-acute model of daunorubicin-induced cardiomyopathy

Rapid changes of mRNA expressions of cardiac ion channels affected by Torsadogenic drugs influence susceptibility of rat hearts to arrhythmias induced by Beta-Adrenergic stimulation

Drug-induced long QT syndrome (LQTS) and Torsades de Pointes (TdP) are serious concerns in drug development. Although rats are a useful scientific tool, their hearts, unlike larger species, usually do not respond to torsadogenic drugs. Consequently, their resistance to drug-induced arrhythmias is poorly understood. Here, we challenged rats with rapid delayed rectifier current (Ikr)-inhibiting antibiotic clarithromycin (CLA), loop diuretic furosemide (FUR) or their combination (CLA + FUR), and examined functional and molecular abnormalities after stimulation with isoproterenol. Clarithromycin and furosemide were administered orally at 12-h intervals for 7 days. To evaluate electrical instability, electrocardiography (ECG) was recorded either in vivo or ex vivo using the Langendorff-perfused heart method under basal conditions and subsequently under beta-adrenergic stimulation. Gene expression was measured using real-time quantitative PCR in left ventricular tissue. Indeed, FUR and CLA + FUR rats exhibited hypokalemia. CLA and CLA + FUR treatment resulted in drug-induced LQTS and even an episode of TdP in one CLA + FUR rat. The combined treatment dysregulated gene expression of several ion channels subunits, including KCNQ1, calcium channels and Na+/K + -ATPase subunits, while both monotherapies had no impact. The rat with recorded TdP exhibited differences in the expression of ion channel genes compared to the rest of rats within the CLA + FUR group. The ECG changes were not detected in isolated perfused hearts. Hence, we report rapid orchestration of ion channel reprogramming of hearts with QT prolongation induced by simultaneous administration of clarithromycin and furosemide in rats, which may account for their ability to avoid arrhythmias triggered by beta-adrenergic stimulation.

Hematocrit-Related Alterations of Circulating microRNA-21 Levels in Heart Failure Patients with Reduced Ejection Fraction: A Preliminary Study

Aim: Circulating microRNA-21 (miR-21) has been utilized as a diagnostic tool in the assessment of heart failure (HF). Blood constitution may be altered when HF occurs and miR-21 may affect hematopoiesis. Sample hemolysis may influence the determination of circulating miRNAs, challenging the diagnostic use of miRNAs. Methods: We examined the relationship between blood measurements and miR-21 levels in ambulant chronic HF patients with reduced ejection fraction (HFrEF; n = 19). Healthy volunteers (n = 11) served as controls. Serum miR-21 levels were measured through quantitative reverse transcription polymerase chain reaction (RT-qPCR) and we calculated the hemolysis score (H-score). Study was approved by an Institutional Review Board (EK FaF UK 02/2018). Results: MiR-21 serum levels were reduced in HFrEF patients compared with the controls (p < 0.05), without relationship to New York Heart Association class, left ventricular ejection fraction or N-terminal prohormone of brain natriuretic peptide levels. MiR-21 levels decreased markedly in anemic patients, compared with those with normal hematocrits (p < 0.05). We found a significant relationship between miR-21 to hematocrit (p < 0.05) and hemoglobin concentration (p < 0.05). Importantly, we found a correlation between hematocrit and sample H-score (p < 0.05) in the cohort of HFrEF patients; however, there was no correlation between hemolysis and miR-21. Conclusion: Circulating miR-21 levels were decreased in HFrEF patients and hematocrit was identified as a factor associated with this abnormality. This suggests that miR-21 mirrors other characteristics of HFrEF patients rather than the standard identifiers of HF severity and progression.

The Effects of Neuropeptide Y Overexpression on the Mouse Model of Doxorubicin-Induced Cardiotoxicity

Doxorubicin is a potent anticancer drug with cardiotoxicity hampering its use. Neuropeptide Y (NPY) is the most abundant neuropeptide in the heart and a co-transmitter of the sympathetic nervous system that plays a role in cardiac diseases. The aim of this work was to study the impact of NPY on doxorubicin-induced cardiotoxicity. Transgenic mice overexpressing NPY in noradrenergic neurons (NPY-OE^DβH) and wild-type mice were treated with a single dose of doxorubicin. Doxorubicin caused cardiotoxicity in both genotypes as demonstrated by decreased weight gain, tendency to reduced ejection fraction, and changes in the expression of several genes relevant to cardiac pathology. Doxorubicin resulted in a tendency to lower ejection fraction in NPY-OE^DβH mice more than in wild-type mice. In addition, gain in the whole body lean mass gain was decreased only in NPY-OE^DβH mice, suggesting a more severe impact of doxorubicin in this genotype. The effects of doxorubicin on genes expressed in the heart were similar between NPY-OE^DβH and wild-type mice. The results demonstrate that doxorubicin at a relatively low dose caused significant cardiotoxicity. There were differences between NPY-OE^DβH and wild-type mice in their responses to doxorubicin that suggest NPY to increase susceptibility to cardiotoxicity. This may point to the therapeutic implications as suggested for NPY system in other cardiovascular diseases.

Disease severity-related alterations of cardiac microRNAs in experimental pulmonary hypertension

Right ventricular (RV) failure is the primary cause of death in pulmonary arterial hypertension (PAH). We hypothesized that heart‐relevant microRNAs, that is myomiRs (miR‐1, miR‐133a, miR‐208, miR‐499) and miR‐214, can have a role in the right ventricle in the development of PAH. To mimic PAH, male Wistar rats were injected with monocrotaline (MCT, 60 mg/kg, s.c.); control group received vehicle. MCT rats were divided into two groups, based on the clinical presentation: MCT group terminated 4 weeks after MCT administration and prematurely terminated group (ptMCT) displaying signs of terminal disease. Myocardial damage genes and candidate microRNAs expressions were determined by RT‐qPCR. Reduced blood oxygen saturation, breathing disturbances, RV enlargement as well as elevated levels of markers of myocardial damage confirmed PH in MCT animals and were more pronounced in ptMCT. MyomiRs (miR‐1/miR‐133a/miR‐208a/miR‐499) were decreased and the expression of miR‐214 was increased only in ptMCT group (P < 0.05). The myomiRs negatively correlated with Fulton index as a measure of RV hypertrophy in MCT group (P < 0.05), whereas miR‐214 showed a positive correlation (P < 0.05). We conclude that the expression of determined microRNAs mirrored the disease severity and targeting their pathways might represent potential future therapeutic approach in PAH.

The functions of microRNA-208 in the heart

Cardiovascular disease is a major chronic complication of obesity and diabetes. Due to several patients with obesity and diabetes, it is necessary to urgently explore early diagnostic biomarkers and innovative therapeutic strategies to prevent the progression of cardiovascular diseases. Recently, microRNAs (also known as miRNAs) have emerged as important players in heart disease and energy regulation. MiRNAs are a group of small, highly conserved non-coding RNA molecules that regulate gene expression by suppressing the translation of messenger RNA of target genes or by promoting mRNA degradation. These act as a class of potential biomarkers and may provide key information in diagnosing common diseases such as tumors, tissue damage, and autoimmune diseases. Among all the known miRNAs, microRNA-208 (miR-208) is specifically expressed in myocardial cells and showed close association with the development of cardiac diseases, such as myocardial hypertrophy, cardiac fibrosis, myocardial infarction, arrhythmia, and heart failure. However, the functions and underlying mechanisms of miR-208 in heart are still unclear. In this review, we highlighted the novel insights of miR-208 functions and associated mechanisms in the regulation of cardiac diseases.

Modeling dynamics and alternative treatment strategies in acute promyelocytic leukemia

Acute Promyelocytic Leukemia (APL) is a rare and potentially lethal condition in which risk-based therapy often leads to better outcomes. Because of its rarity and relatively high overall survival rate, prospective randomized trials to investigate alternative APL treatment schedules are challenging. Mathematical models may provide useful information in this regard. We collected clinical data from 38 patients treated for APL under the International Consortium on Acute Leukemia (ICAL) protocol and laboratory data during induction therapy. We propose a mathematical model that represents the dynamics of leukocytes in peripheral blood and the effect of ICAL treatment on the disease’s dynamics. We observe that our cohort presents demographic characteristics and clinical outcomes similar to previous clinical trials on APL. Over a follow-up period of 41.8 months, the relapse-free survival and overall survival at two years are both found to be 78.7%. For two selected patients, the model produces a good fit to the clinical data. Information such as the response to treatment and risk of relapse can be derived from the model, and this may assist in clinical practice and the design of clinical trials.

Pegfilgrastim and linagliptin potentiate chemoattraction of Ccr2 and Cd44 stem cells accompanied by alterations of cardiac Hgf, Igf-1 and Mcp-1 in daunorubicin cardiomyopathy

Objective

Daunorubicin (DAU) downregulates cytokines promoting stem cell migration and homing into the heart, reducing cardiac regeneration after anticancer chemotherapy. Pegfilgrastim (PFIL) protects from DAU-induced neutropenia but its cardioprotective potential remains unclear. We tested whether pegfilgrastim and a dipeptidyl peptidase-4 inhibitor linagliptin, potential enhancers of stem cells migration and homing, would improve DAU-cardiomyopathy.

Methods

DAU (7.5 mg/kg, i.v.) was administered to male Wistar rats to induce cardiotoxicity. Pegfilgrastim (100 µg/kg, s.c.) was administered 24h after DAU, and linagliptin was administered orally for 8 weeks (5 mg/kg/day, LINA). Cardiac damage markers (Nppa, Myh6, Myh7, Gp91phox), cytokines (Sdf-1alpha, Mcp-1, Vegf, Hgf, Igf-1), stem cell markers (Cxcr4, Ccr2, Cd34, Cd133, Cd44, Cd105) were determined by qRT-PCR.

Key findings

Decreased Myh6, elevated Myh7 Nppa, and Gp91phox were not ameliorated by PFIL + LINA. Downregulated expressions of cytokines (Vegf, Sdf-1alpha) and stem cells markers (Cxcr4, Cd34, Cd133, and Cd105) remained decreased after PFIL + LINA. DAU-induced upregulation of Mcp-1, Ccr2 and Cd44 was further potentiated by PFIL + LINA. PFIL + LINA normalised expression of Hgf and Igf-1.

Conclusions

Although PFIL + LINA failed in universal potentiation of stem cells migration and homing, the expression of stem cell markers Ccr2 and Cd44 in the heart potentially increased through the preservation of Hgf, Igf-1 and upregulation of Mcp-1.

SDF-1 and its receptor in the ventricles of rat with monocrotaline-induced pulmonary hypertension

Aim: Chemokine stromal cell derived factor-1 (SDF-1) plays an important role in many processes such as apoptosis, proliferation, migration and angiogenesis, and these effects are mediated mostly by the receptor CXCR4. The aim of this study was to determine the expression of SDF-1 and CXCR4 in the ventricles of rats with monocrotaline-induced pulmonary hypertension.

Methods: 10–12 weeks old male Wistar rats were injected with monocrotaline (s. c., 60mg/kg; MON) or vehicle (CON). Rats were sacrificed 1 week (1W-MON, 1W-CON), 2 weeks (2W-MON, 2W-CON) and 4 weeks after monocrotaline administration (4W-MON, 4W-CON). Gene expression of SDF-1 and CXCR4 was determined by qRT-PCR.

Results: We observed a decrease in the SDF-1 expression on mRNA level in the right ventricle in 2W-MON and 4W-MON rats without any changes in the left ventricles and a decrease in CXCR4 expression in 1W-MON in both ventricles with an increase of CXCR4 expression in 4W-MON in the left ventricle (*P ˂ 0.05).

Conclusion: SDF-1/CXCR4 axis is affected in both ventricles of rats with monocrotaline model of pulmonary hypertension.