bims-hafaim Biomed News
on Heart Failure Metabolism
Issue of 2021‒04‒18
seven papers selected by
Kyle McCommis
Saint Louis University

  1. Hypertension. 2021 Apr 12. HYPERTENSIONAHA12016445
      NEP (Neprilysin) degrades natriuretic peptides, and its inhibition is a clinically accepted target for heart failure treatment. NEP is widely expressed in various organs, including the heart. However, the pathophysiological significance of local cardiac NEP is not fully understood. To study the local function of NEP in the heart, we generated transgenic mice overexpressing NEP, specifically in cardiomyocytes (CM-NEP Tg). At baseline, CM-NEP Tg mice showed significantly lower levels of plasma ANP (atrial natriuretic peptide), plasma cGMP, and cardiac tissue cGMP versus wild-type (WT) mice. Blood pressure, heart weight, and cardiomyocyte diameter were greater in CM-NEP Tg than WT mice. There were no significant differences in interstitial fibrosis or ejection fraction. Transverse aortic constriction (TAC) surgery significantly increased left ventricular weight in WT and CM-NEP Tg mice 3 weeks post-op versus sham surgery; however, the cardiac hypertrophic response to TAC was higher in CM-NEP Tg than WT mice. Cardiac interstitial fibrosis was induced in TAC CM-NEP Tg mice, whereas TAC WT mice had none. TAC CM-NEP Tg, but not TAC WT, mice developed cardiac dysfunction secondary to TAC with echocardiography. Furthermore, administration of human ANP to raise plasma ANP levels comparable to those in WT mice neither improved the exacerbated cardiac hypertrophy and fibrosis nor recovered impaired cardiac function in CM-NEP Tg mice after TAC. In conclusion, overexpression of NEP in cardiomyocytes promoted degradation of natriuretic peptides in the heart and led to an exaggerated response of hypertrophy and fibrosis to pressure overload.
    Keywords:  guanosine monophosphate; heart failure; natriuretic peptides; neprilysin; plasma
  2. J Am Heart Assoc. 2021 Apr 14. e019486
      Background Orai3 is a mammalian-specific member of the Orai family (Orai1‒3) and a component of the store-operated Ca2+ entry channels. There is little understanding of the role of Orai channels in cardiomyocytes, and its role in cardiac function remains unexplored. Thus, we developed mice lacking Orai1 and Orai3 to address their role in cardiac homeostasis. Methods and Results We generated constitutive and inducible cardiomyocyte-specific Orai3 knockout (Orai3cKO) mice. Constitutive Orai3-loss led to ventricular dysfunction progressing to dilated cardiomyopathy and heart failure. Orai3cKO mice subjected to pressure overload developed a fulminant dilated cardiomyopathy with rapid heart failure onset, characterized by interstitial fibrosis and apoptosis. Ultrastructural analysis of Orai3-deficient cardiomyocytes showed abnormal M- and Z-line morphology. The greater density of condensed mitochondria in Orai3-deficient cardiomyocytes was associated with the upregulation of DRP1 (dynamin-related protein 1). Cardiomyocytes isolated from Orai3cKO mice exhibited profoundly altered myocardial Ca2+ cycling and changes in the expression of critical proteins involved in the Ca2+ clearance mechanisms. Upregulation of TRPC6 (transient receptor potential canonical type 6) channels was associated with upregulation of the RCAN1 (regulator of calcineurin 1), indicating the activation of the calcineurin signaling pathway in Orai3cKO mice. A more dramatic cardiac phenotype emerged when Orai3 was removed in adult mice using a tamoxifen-inducible Orai3cKO mouse. The removal of Orai1 from adult cardiomyocytes did not change the phenotype of tamoxifen-inducible Orai3cKO mice. Conclusions Our results identify a critical role for Orai3 in the heart. We provide evidence that Orai3-mediated Ca2+ signaling is required for maintaining sarcomere integrity and proper mitochondrial function in adult mammalian cardiomyocytes.
    Keywords:  Orai3; calcium signaling; dilated cardiomyopathy; ion channels
  3. Can J Cardiol. 2021 Apr 07. pii: S0828-282X(21)00174-4. [Epub ahead of print]
      BACKGROUND: Downregulation of claudin-5 in the heart is associated with the end-stage heart failure. However, the underlying mechanism of claudin-5 is unclear. Here we investigated the molecular actions of claudin-5 in perspective of mitochondria in cardiomyocytes to better understand the role of claudin-5 in cardioprotection during ischemia.METHODS AND RESULTS: Claudin-5 was detected in the murine heart tissue and the neonatal rat cardiomyocytes (NRCM). Its protein level was severely decreased after myocardial ischemia/reperfusion (I/R; 30 min/24 h) or hypoxia/reoxygenation (H/R; 24 h/4 h). Claudin-5 was present in the mitochondria of NRCM as determined by confocal microscopy. H/R-induced downregulation of claudin-5 was accompanied by mitochondrial fragmentation. The protein level of mitofusin 2 (Mfn2) was dramatically decreased while the expression of dynamin-related protein (Drp) 1 was significantly increased after H/R. H/R-induced mitochondrial swelling and fission were observed by transmission electron microscope (TEM). Overexpression of claudin-5 by adenoviral infection reversed these structural disintegration of mitochondria. The mitochondria-centered intrinsic pathway of apoptosis triggered by H/R and indicated by the expression of cytochrome c and cleaved caspase 3 in the cytoplasm of NRCMs was also reduced by overexpressing claudin-5. Overexpression of claudin-5 in mouse heart also significantly decreased cleaved caspase 3 expression and the infarct size in ischemic heart with improved systolic function.
    CONCLUSION: We demonstrated for the first time the presence of claudin-5 in the mitochondria in cardiomyocytes and provided the firm evidence for the cardioprotective role of claudin-5 in the preservation of mitochondrial dynamics and cell fate against hypoxia- or ischemia-induced stress.
    Keywords:  Claudin-5; Hypoxia/reoxygenation; Mirochondrial fragmentation; Mitochondrial dynamics; Myocardial ischemia/reperfusion
  4. Cardiol Res Pract. 2021 ;2021 6657380
      Sodium-glucose cotransporter-2 (SGLT2) inhibitors represent newly developed oral antidiabetic drugs that are practiced for type 2 diabetes mellitus management and may decrease the risk of the first hospitalization in heart failure. The activity of SGLT2 inhibitors is not related to glucose, and the effectiveness and safety of SGLT2 inhibitors in individuals with chronic heart failure (CHF) remain unclear. We systematically retrieved PubMed, Cochrane Library, Embase, NCKI, VIP, Wanfang Data, and records to identify eligible trials. The primary endpoints were cardiovascular death/hospitalization for heart failure (CV death/HHF), cardiovascular death, and hospitalization for heart failure. Secondary endpoints included hypoglycemia, volume depletion, urinary tract infection, left ventricular ejection fraction (LVEF), and NT-proBNP. Nine randomized controlled clinical trials were included. Dapagliflozin was reported to significantly decrease CV death/HHF (relative risk (RR): 0.75; 95% confidence interval (CI): 0.68-0.84), CV death (RR: 0.80; 95% CI: 0.68-0.93), and HHF (RR: 0.72; 95% CI: 0.63-0.83). There was no effect on hypoglycemia (RR: 0.69; 95% CI: 0.34-1.40), volume depletion (RR: 1.17; 95% CI: 0.97-1.41), urinary tract infection (RR: 0.82; 95% CI: 0.43-1.57), LVEF (WMD: 0.53; 95% CI: -4.04-5.09), or NT-proBNP (SMD: -0.66; 95% CI: -1.42-0.10). The risk of CV death/HHF, CV death, and HHF was lower among patients receiving dapagliflozin than patients receiving placebo.
  5. Front Mol Biosci. 2021 ;8 641585
      Cardiac hypertrophic preconditioning (HP) signifies cardioprotection induced by transient pressure overload to resist hypertrophic effects of subsequently sustained pressure overload. Although it is recently found that inflammation triggers the development of nonischemic cardiomyopathy, whether inflammation plays a role in the antecedent protective effects of HP remains unknown. Caspase-1 is a critical proinflammatory caspase that also induces pyroptosis; thus, we investigated the role of caspase-1 using a unique model of HP in mice subjected longitudinally to 3 days of transverse aortic constriction (TAC 3d), 4 days of de-constriction (De-TAC 4d), and 4 weeks of Re-TAC (Re-TAC 4W). Echocardiography, hemodynamics, histology, PCR, and western blot confirmed preserved cardiac function, alleviated myocardial hypertrophy and fibrosis, and less activated hypertrophic signaling effectors in Re-TAC 4W mice, compared with TAC 4W mice. Mechanistically, caspase-1 and its downstream targets IL-1β and IL-18, but not GSDMD, were less activated in Re-TAC 4W mice. Furthermore, in HP mice with AAV-9-mediated cardiac-specific caspase-1 overexpression, the salutary effects of HP were remarkably abrogated, as evidenced by exacerbated cardiac remodeling, dysfunction, and activation of IL-1β and IL-18. Collectively, this study revealed a previously unrecognized involvement of caspase-1 in cardiac HP by regulation of IL-1β and IL-18 and shed light on caspase-1 as an antecedent indicator and target for cardiac hypertrophy.
    Keywords:  MAPK; cardiac hypertrophy; caspase-1; hypertrophic preconditioning; inflammation
  6. Circ Res. 2021 Apr 16. 128(8): 1205-1207
    Keywords:  Editorials; animal models; calcium; cardiac myocyte; heart failure; mitochondria
  7. J Diabetes Res. 2021 ;2021 8838026
      Objectives: A single-arm prospective study was conducted among Japanese patients with type 2 diabetes having preserved ejection fraction. The aim was to investigate (1) whether liraglutide therapy could improve B-type natriuretic peptide (BNP) levels and diastolic cardiac function assessed by the E-wave to E' ratio (E/E') using transthoracic echocardiography (TTE), and (2) whether E/E' contributed to BNP improvement independent of bodyweight reduction (UMIN000005565).Methods: Patients with type 2 diabetes and left ventricular ejection fraction (LVEF) ≥ 40% without heart failure symptoms were enrolled, and daily injection with liraglutide (0.9 mg) was introduced. Cardiac functions were assessed by TTE before and after 26 weeks of liraglutide treatment. Diastolic cardiac function was defined as septal E/E' ≥ 13.0.
    Results: Thirty-one patients were analyzed. BNP and E/E' improved, with BNP levels declining from 36.8 ± 30.5 pg/mL to 26.3 ± 25.9 pg/mL (p = 0.0014) and E/E' dropping from 12.7 ± 4.7 to 11.0 ± 3.3 (p = 0.0376). The LVEF showed no significant changes. E/E' improved only in patients with E/E' ≥ 13.0. Favorable changes in E/E' were canceled when adjusted for body mass index (BMI). Multivariate linear regression analysis revealed that the left ventricular diastolic diameter and ∆E/E'/∆BMI contributed to ∆BNP/baseline BNP (p = 0.0075, R 2 = 0.49264).
    Conclusions: Liraglutide had favorable effects on BNP and E/E' but not on LVEF. E/E' improvement was only seen in patients with diastolic cardiac function. Body weight reduction affected the change of E/E'. The BMI-adjusted E/E' significantly contributed to the relative change of BNP. GLP-1 analog treatment could be considered a therapeutic option against diabetic diastolic cardiac dysfunction regardless of body weight. This trial is registered with the University Hospital Medical Information Network in Japan, with clinical trial registration number: UMIN000005565.