Hyaluronan and collagen in human hypertrophic cardiomyopathy: a morphological analysis

Pterostilbene Attenuates Fructose-Induced Myocardial Fibrosis by Inhibiting ROS-Driven Pitx2c/miR-15b Pathway

Excessive fructose consumption induces oxidative stress and myocardial fibrosis. Antioxidant compound pterostilbene has cardioprotective effect in experimental animals. This study is aimed at investigating how fructose drove fibrotic responses via oxidative stress in cardiomyocytes and explored the attenuation mechanisms of pterostilbene. We observed fructose-induced myocardial hypertrophy and fibrosis with ROS overproduction in rats. Paired-like homeodomain 2 (Pitx2c) increase, microRNA-15b (miR-15b) low expression, and p53 phosphorylation (p-p53) upregulation, as well as activation of transforming growth factor-β1 (TGF-β1)/drosophila mothers against DPP homolog (Smads) signaling and connective tissue growth factor (CTGF) induction, were also detected in fructose-fed rat hearts and fructose-exposed rat myocardial cell line H9c2 cells. The results from p53 siRNA or TGF-β1 siRNA transfection showed that TGF-β1-induced upregulation of CTGF expression and p-p53 activated TGF-β1/Smads signaling in fructose-exposed H9c2 cells. Of note, Pitx2c negatively modulated miR-15b expression via binding to the upstream of the miR-15b genetic loci by chromatin immunoprecipitation and transfection analysis with pEX1-Pitx2c plasmid and Pitx2c siRNA, respectively. In H9c2 cells pretreated with ROS scavenger N-acetylcysteine, or transfected with miR-15b mimic and inhibitor, fructose-induced cardiac ROS overload could drive Pitx2c-mediated miR-15b low expression, then cause p-p53-activated TGF-β1/Smads signaling and CTGF induction in myocardial fibrosis. We also found that pterostilbene significantly improved myocardial hypertrophy and fibrosis in fructose-fed rats and fructose-exposed H9c2 cells. Pterostilbene reduced cardiac ROS to block Pitx2c-mediated miR-15b low expression and p-p53-dependent TGF-β1/Smads signaling activation and CTGF induction in high fructose-induced myocardial fibrosis. These results firstly demonstrated that the ROS-driven Pitx2c/miR-15b pathway was required for p-p53-dependent TGF-β1/Smads signaling activation in fructose-induced myocardial fibrosis. Pterostilbene protected against high fructose-induced myocardial fibrosis through the inhibition of Pitx2c/miR-15b pathway to suppress p-p53-activated TGF-β1/Smads signaling, warranting the consideration of Pitx2c/miR-15b pathway as a therapeutic target in myocardial fibrosis.

Low Molecular Mass Myocardial Hyaluronan in Human Hypertrophic Cardiomyopathy

During the development of hypertrophic cardiomyopathy, the heart returns to fetal energy metabolism where cells utilize more glucose instead of fatty acids as a source of energy. Metabolism of glucose can increase synthesis of the extracellular glycosaminoglycan hyaluronan, which has been shown to be involved in the development of cardiac hypertrophy and fibrosis. The aim of this study was to investigate hyaluronan metabolism in cardiac tissue from patients with hypertrophic cardiomyopathy in relation to cardiac growth. NMR and qRT-PCR analysis of human cardiac tissue from hypertrophic cardiomyopathy patients and healthy control hearts showed dysregulated glucose and hyaluronan metabolism in the patients. Gas phase electrophoresis revealed a higher amount of low molecular mass hyaluronan and larger cardiomyocytes in cardiac tissue from patients with hypertrophic cardiomyopathy. Histochemistry showed high concentrations of hyaluronan around individual cardiomyocytes in hearts from hypertrophic cardiomyopathy patients. Experimentally, we could also observe accumulation of low molecular mass hyaluronan in cardiac hypertrophy in a rat model. In conclusion, the development of hypertrophic cardiomyopathy with increased glucose metabolism affected both hyaluronan molecular mass and amount. The process of regulating cardiomyocyte size seems to involve fragmentation of hyaluronan.

The relationship between plasma hyaluronan levels and anthracycline-related cardiotoxicity in breast cancer patients

AIM

Anthracycline-derived antineoplastic agents are used as the main form of treatment in many malignant diseases, including breast cancer and childhood cancers. Cardiotoxicity is one of the most feared life-threatening complications of cancer therapy. In the present study, we aimed to investigate the relationship between plasma hyaluronan (HA) levels and anthracycline-induced cardiotoxicity.

MATERIALS AND METHODS

Fifty eight of 73 female patients who were diagnosed with breast cancer and treated with a chemotherapy regimen including anthracycline were enrolled in this study. Anamneses were taken from each patient before and after chemotherapy. Further, physical examinations, electrocardiography, and transthoracic echocardiography were performed, and plasma hyaluronan levels were determined by using ELISA assay for each patient before and after treatment.

RESULTS

Following anthracycline-based chemotherapy, the average left ventricular ejection fraction decreased (62.6±3.7% vs. 58.6±4.4%, p<0.001), and diastolic functions significantly deteriorated (p<0.001). However, troponin and hyaluronan levels significantly increased following chemotherapy [Troponin (ng/ml, mean±SD): before 0.01±0.002, after 0.037±0.02, p<0.001], [Plasma HA (ng/ml, mean±SD): before 41.3±5.4, after 70±8.5, p<0.001]. The increase in troponin values correlated with systolic dysfunction (p=0.002), but did not correlate with diastolic dysfunction (p=0.661). Significant correlations were found between systolic/diastolic dysfunction and plasma HA levels (r=0.417, p=0.001; r=0.339, p=0.009, respectively).

CONCLUSIONS

Both systolic and diastolic functions were significantly deteriorated after chemotherapy. In addition, plasma levels of HA and troponin increased after treatment. Further, both systolic and diastolic dysfunctions were found to correlate with serum HA levels. All these data suggest that HA might have a function on anthracycline-induced cardiotoxicity.