bims-hafaim 2021-07-25 papers

Issue of 2021–07–25
five papers selected by
Kyle McCommis, Saint Louis University

Eur Heart J. 2021 Jul 23. pii: ehab412. [Epub ahead of print]

Glucosylceramide synthase deficiency in the heart compromises β1-adrenergic receptor trafficking.

AIMS : Cardiac injury and remodelling are associated with the rearrangement of cardiac lipids. Glycosphingolipids are membrane lipids that are important for cellular structure and function, and cardiac dysfunction is a characteristic of rare monogenic diseases with defects in glycosphingolipid synthesis and turnover. However, it is not known how cardiac glycosphingolipids regulate cellular processes in the heart. The aim of this study is to determine the role of cardiac glycosphingolipids in heart function.
METHODS AND RESULTS : Using human myocardial biopsies, we showed that the glycosphingolipids glucosylceramide and lactosylceramide are present at very low levels in non-ischaemic human heart with normal function and are elevated during remodelling. Similar results were observed in mouse models of cardiac remodelling. We also generated mice with cardiomyocyte-specific deficiency in Ugcg, the gene encoding glucosylceramide synthase (hUgcg-/- mice). In 9- to 10-week-old hUgcg-/- mice, contractile capacity in response to dobutamine stress was reduced. Older hUgcg-/- mice developed severe heart failure and left ventricular dilatation even under baseline conditions and died prematurely. Using RNA-seq and cell culture models, we showed defective endolysosomal retrograde trafficking and autophagy in Ugcg-deficient cardiomyocytes. We also showed that responsiveness to β-adrenergic stimulation was reduced in cardiomyocytes from hUgcg-/- mice and that Ugcg knockdown suppressed the internalization and trafficking of β1-adrenergic receptors.
CONCLUSIONS : Our findings suggest that cardiac glycosphingolipids are required to maintain β-adrenergic signalling and contractile capacity in cardiomyocytes and to preserve normal heart function.

Keywords: Cardiac dysfunction; Endolysosomal trafficking; Adrenergic; Autophagy; Beta; Glycosphingolipids; Lipids; Receptors

DOI: https://doi.org/10.1093/eurheartj/ehab412

Int J Environ Res Public Health. 2021 Jul 16. pii: 7598. [Epub ahead of print]18(14):

Heart Metabolism in Sepsis-Induced Cardiomyopathy-Unusual Metabolic Dysfunction of the Heart.

Weronika Wasyluk, Patrycja Nowicka-Stążka, Agnieszka Zwolak.

Due to the need for continuous work, the heart uses up to 8% of the total energy expenditure. Due to the relatively low adenosine triphosphate (ATP) storage capacity, the heart's work is dependent on its production. This is possible due to the metabolic flexibility of the heart, which allows it to use numerous substrates as a source of energy. Under normal conditions, a healthy heart obtains approximately 95% of its ATP by oxidative phosphorylation in the mitochondria. The primary source of energy is fatty acid oxidation, the rest of the energy comes from the oxidation of pyruvate. A failed heart is characterised by a disturbance in these proportions, with the contribution of individual components as a source of energy depending on the aetiology and stage of heart failure. A unique form of cardiac dysfunction is sepsis-induced cardiomyopathy, characterised by a significant reduction in energy production and impairment of cardiac oxidation of both fatty acids and glucose. Metabolic disorders appear to contribute to the pathogenesis of cardiac dysfunction and therefore are a promising target for future therapies. However, as many aspects of the metabolism of the failing heart remain unexplained, this issue requires further research.

Keywords: cardiac metabolism; heart failure; intensive care; metabolic remodelling; sepsis; sepsis-induced cardiomyopathy

DOI: https://doi.org/10.3390/ijerph18147598

Cardiovasc Diagn Ther. 2021 Jun;11(3): 699-706

Factors affecting the efficacy of SGLT2is on heart failure events: a meta-analysis based on cardiovascular outcome trials.

Mei Qiu, Liang-Liang Ding, Hai-Rong Zhou.

Background: The efficacy of sodium-glucose transporter 2 inhibitors (SGLT2is) on heart failure outcomes is unestablished in various subgroups defined by clinically important factors. We intended to evaluate the effects of six important factors on the efficacy of SGLT2is on heart failure outcomes.
Methods: We included cardiovascular outcome trials (CVOTs) concerning SGLT2is. We assessed the heart failure composite outcome of cardiovascular death (CVD) or hospitalization for heart failure (HHF). Meta-analysis was conducted stratified by the following 6 factors: type of underlying diseases, type of SGLT2is, left ventricular ejection fraction (LVEF) level, New York Heart Association (NYHA) class, region, and race.
Results: Ten CVOTs were included. Compared with placebo, SGLT2is reduced heart failure composite outcome by 25% [hazard ratio (HR) 0.75, 95% confidence interval (CI), 0.72-0.78] independent of type of underlying diseases, type of SGLT2is, LVEF level, and region (Psubgroup: 0.673, 0.244, 0.429, and 0.127, respectively). SGLT2is led to greater reduction in the composite outcome in patients with NYHA class II (HR 0.66, 95% CI, 0.59-0.74) than in patients with NYHA class III or IV (HR 0.86, 95% CI, 0.75-0.99; Psubgroup=0.004), and in Black (HR 0.63, 95% CI, 0.49-0.82) and Asian (HR 0.64, 95% CI, 0.53-0.77) patients than in White patients (HR 0.81, 95% CI, 0.76-0.86; Psubgroup=0.016).
Conclusions: SGLT2is reduce heart failure composite outcome by 25% independent of type of underlying diseases, type of SGLT2is, LVEF level, and region. SGLT2is lead to greater reduction in the composite outcome in patients with NYHA class II than in patients with NYHA class III or IV, and in Black and Asian patients than in White patients.
Keywords: Sodium-glucose transporter 2 inhibitors (SGLT2is); heart failure; chronic kidney disease (CKD); type 2 diabetes.

DOI: https://doi.org/10.21037/cdt-20-984

Cardiovasc Diabetol. 2021 Jul 23. 20(1): 150

The SGLT-2 inhibitor empagliflozin improves myocardial strain, reduces cardiac fibrosis and pro-inflammatory cytokines in non-diabetic mice treated with doxorubicin.

Vincenzo Quagliariello, Michelino De Laurentiis, Domenica Rea, Antonio Barbieri, Maria Gaia Monti, Andreina Carbone, Andrea Paccone, Lucia Altucci, Mariarosaria Conte, Maria Laura Canale, Gerardo Botti, Nicola Maurea.

BACKGROUND: Empagliflozin (EMPA), a selective inhibitor of the sodium glucose co-transporter 2, reduced the risk of hospitalization for heart failure and cardiovascular death in type 2 diabetic patients in the EMPA-REG OUTCOME trial. Recent trials evidenced several cardio-renal benefits of EMPA in non-diabetic patients through the involvement of biochemical pathways that are still to be deeply analysed. We aimed to evaluate the effects of EMPA on myocardial strain of non-diabetic mice treated with doxorubicin (DOXO) through the analysis of NLRP3 inflammasome and MyD88-related pathways resulting in anti-apoptotic and anti-fibrotic effects.
METHODS: Preliminary cellular studies were performed on mouse cardiomyocytes (HL-1 cell line) exposed to doxorubicin alone or combined to EMPA. The following analysis were performed: determination of cell viability (through a modified MTT assay), study of intracellular ROS production, lipid peroxidation (quantifying intracellular malondialdehyde and 4-hydroxynonenal), intracellular Ca2+ homeostasis. Moreover, pro-inflammatory studies were also performed: expression of NLRP3 inflammasome, MyD88 myddosome and p65/NF-κB associated to secretion of cytokines involved in cardiotoxicity (Interleukins 1β, 8, 6). C57Bl/6 mice were untreated (Sham, n = 6) or treated for 10 days with doxorubicin (DOXO, n = 6), EMPA (EMPA, n = 6) or doxorubicin combined to EMPA (DOXO-EMPA, n = 6). DOXO was injected intraperitoneally. Ferroptosis and xanthine oxidase were studied before and after treatments. Cardiac function studies, including EF, FS and radial/longitudinal strain were analysed through transthoracic echocardiography (Vevo 2100). Cardiac fibrosis and apoptosis were histologically studied through Picrosirius red and TUNEL assay, respectively and quantified through pro-collagen-1α1, MMP-9 and Caspase-3 expression. Tissue NLRP3, MyD88 and cytokines were also quantified before and after treatments through ELISA methods.
RESULTS: Cardiomyocytes exposed to doxorubicin increased the intracellular Ca2+ content and expression of several pro-inflammatory markers associated to cell death; co-incubation with EMPA reduced significantly the magnitude of the effects. In preclinical study, EMPA increased EF and FS compared to DOXO groups (p < 0.05), prevented the reduction of radial and longitudinal strain after 10 days of treatment with doxorubicin (RS) 30.3% in EMPA-DOXO vs 15.7% in DOXO mice; LS - 17% in EMPA-DOXO vs - 11.7% in DOXO mice (p < 0.001 for both). Significant reductions in ferroptosis, xanthine oxidase expression, cardiac fibrosis and apoptosis in EMPA associated to DOXO were also seen. A reduced expression of pro-inflammatory cytokines, NLRP3, MyD88 and NF-kB in heart, liver and kidneys was also seen in DOXO-EMPA group compared to DOXO (p < 0.001).
CONCLUSION: EMPA reduced ferroptosis, fibrosis, apoptosis and inflammation in doxorubicin-treated mice through the involvement of NLRP3 and MyD88-related pathways, resulting in significant improvements in cardiac functions. These findings provides the proof of concept for translational studies designed to reduce adverse cardiovascular outcomes in non-diabetic cancer patients treated with doxorubicin.

Keywords: Cardio-Oncology; Doxorubicin; EMPA; Inflammation; Interleukins

DOI: https://doi.org/10.1186/s12933-021-01346-y

Cardiovasc Ther. 2021 ;2021 9995342

Wogonin Inhibits Cardiac Hypertrophy by Activating Nrf-2-Mediated Antioxidant Responses.

Xiaowen Shi, Bin Zhang, Zhenliang Chu, Bingjiang Han, Xueping Zhang, Ping Huang, Jibo Han.

Background: Cardiac hypertrophy is one of the initial disorders of the cardiovascular system and can induce heart failure. Oxidative stress is an important pathophysiological mechanism of cardiac hypertrophy. Wogonin (Wog), an important flavonoid derived from the root of Scutellaria baicalensis Georgi, is known to possess antioxidant properties.
Methods: An in vitro model of cardiac hypertrophy was established by stimulating H9C2 cells and neonatal rat cardiomyocytes (NRCMs) with angiotensin II (AngII). The indices related to myocardial hypertrophy and oxidative stress were detected. An in vivo model of cardiac hypertrophy was induced by transverse aortic constriction (TAC) in C57BL/6 mice. Cardiac function was monitored by chest echocardiography, and the hypertrophy index was measured. The mice were then sacrificed for histological assays, with mRNA and protein detection. To further explore the role of nuclear factor- (erythroid-derived 2-) like 2 (Nrf-2) in regulating the antioxidant effects of Wog in cardiac hypertrophy, siRNA analysis was conducted.
Results: Our results showed that Wog significantly ameliorated AngII-induced cardiomyocyte hypertrophy by inhibiting oxidative stress in H9C2 cells and NRCMs. In addition, Wog treatment prevented oxidative stress and improved cardiac hypertrophy in mice that underwent TAC. Using gene-specific siRNA for Nrf-2, we discovered that these antioxidative effects of Wog are mediated through Nrf-2 induction.
Conclusions: Our results provide further evidence for the potential use of Wog as an antioxidative agent for treatment of cardiac hypertrophy, and Nrf-2 might serve as a therapeutic target in the treatment of cardiac hypertrophy.

DOI: https://doi.org/10.1155/2021/9995342