bims-hafaim Biomed News
on Heart failure metabolism
Issue of 2021‒08‒01
eight papers selected by
Kyle McCommis
Saint Louis University

  1. Front Pharmacol. 2021 ;12 683156
      The clinical controversy of rosiglitazone as a hypoglycemic agent is potentially associated with heart failure, mainly due to its potent activation of peroxisome proliferator-activated receptor γ (PPARγ). PPARγ partial agonists showed superior pharmacological profiles to rosiglitazone. This study compared differences in cardiac morphology and function of the PPARγ partial agonist CMHX008 with rosiglitazone. High-fat diet (HFD) induced obese mice, ob/ob mice and cardiomyocytes overexpressing PPARγ2 were treated with CMHX008 or rosiglitazone. Heart function, myocardial morphology, and hypertrophy-related gene expression were examined. Clinical information from patients with type 2 diabetes mellitus (T2DM) who had taken rosiglitazone and undergone Doppler echocardiography was collected. HFD and ob/ob mice significantly developed cardiac contractile dysfunction, with upregulated PPARγ2 protein levels in heart tissues. Cardiomyocytes of HFD and ob/ob mice were disorderly arranged, the cell areas expanded, and collagen accumulated. In vitro cardiomyocytes overexpressing PPARγ2 displayed obvious structural abnormalities and high mRNA levels of ANP and BNP, critical cardiac hypertrophy-related genes. HFD-fed mice treated with rosiglitazone or CMHX008 had significantly improved cardiac function, but rosiglitazone induced higher expression of ANP and βMHC and hypertrophic cardiomyopathy, while CMHX008 did not. Patients with T2DM taking rosiglitazone exhibited increased thickness of the posterior wall and the ventricular septum, suggesting cardiac hypertrophy. Our findings show that diabetic cardiomyopathy was associated with ectopic overexpression of PPARγ2. The full agonist rosiglitazone prevents cardiac dysfunction at the expense of compensatory hypertrophy, while the partial agonist CMHX008 shared a comparable protective effect without altering the structure of cardiomyocytes.
    Keywords:  PPARγ; cardiac hypertrophy; diabetic cardiomyopathy; insulin sensitizers; rosiglitazone
  2. JAMA Cardiol. 2021 Jul 28.
      Importance: Sodium glucose cotransporter 2 inhibitors reduce morbidity and mortality in patients with heart failure and reduced ejection fraction (HFrEF). Clinicians may find estimates of the projected long-term benefits of sodium glucose cotransporter 2 inhibitors a helpful addition to clinical trial results when communicating the benefits of this class of drug to patients.Objective: To estimate the projected long-term treatment effects of dapagliflozin in patients with HFrEF over the duration of a patient's lifetime.
    Design, Setting, and Participants: Exploratory analysis was performed of Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure (DAPA-HF), a phase 3 randomized, placebo-controlled clinical trial conducted at 410 sites in 20 countries. Patients with an ejection fraction less than or equal to 40% in New York Heart Association functional classification II to IV and elevated plasma levels of N-terminal pro B-type natriuretic peptide were enrolled between February 15, 2017, and August 17, 2018, with final follow-up on June 6, 2019. Mean (SD) duration of follow-up was 17.6 (5.2) months.
    Interventions: Dapagliflozin, 10 mg, once daily vs placebo in addition to standard therapy.
    Main Outcomes and Measures: The primary composite outcome was time to first hospitalization for heart failure, urgent heart failure visit requiring intravenous therapy, or cardiovascular death. The trial results were extrapolated to estimate the projected long-term treatment effects of dapagliflozin over the duration of a patient's lifetime for the primary outcome and the secondary outcome of death from any cause.
    Results: A total of 4744 patients (1109 women [23.4%]; 3635 men [76.6%]) were randomized in DAPA-HF, with a mean (SD) age of 66.3 (10.9) years. The extrapolated mean event-free survival for an individual aged 65 years from a primary composite end point event was 6.2 years for placebo and 8.3 years for dapagliflozin, representing an event-free survival time gain of 2.1 years (95% CI, 0.8-3.3 years; P = .002). When considering death from any cause, mean extrapolated life expectancy for an individual aged 65 years was 9.1 years for placebo and 10.8 years for dapagliflozin, with a gain in survival of 1.7 years (95% CI, 0.1-3.3; P = .03) with dapagliflozin. Similar results were seen when extrapolated across the age range studied. In analyses of subgroups of patients in DAPA-HF, consistent benefits were seen with dapagliflozin on both event-free and overall survival.
    Conclusions and Relevance: These findings indicate that dapagliflozin provides clinically meaningful gains in extrapolated event-free and overall survival. These findings may be helpful in communicating the benefits of this treatment to patients with HFrEF.
    Trial Registration: Identifier: NCT03036124.
  3. Am J Physiol Cell Physiol. 2021 07 28.
      Mitochondria are recognized as signaling organelles because, under stress, mitochondria can trigger various signaling pathways to coordinate the cell's response. The specific pathway(s) engaged by mitochondria in response to mitochondrial energy defects in vivo and in high-energy tissues like the heart are not fully understood. Here, we investigated cardiac pathways activated in response to mitochondrial energy dysfunction by studying mice with cardiomyocyte-specific loss of the mitochondrial phosphate carrier (SLC25A3), an established model that develops cardiomyopathy as a result of defective mitochondrial ATP synthesis. Mitochondrial energy dysfunction induced a striking pattern of acylome remodeling, with significantly increased post-translational acetylation and malonylation. Mass spectrometry-based proteomics further revealed that energy dysfunction-induced remodeling of the acetylome and malonylome preferentially impacts mitochondrial proteins. Acetylation and malonylation modified a highly interconnected interactome of mitochondrial proteins, and both modifications were present on the enzyme isocitrate dehydrogenase 2 (IDH2). Intriguingly, IDH2 activity was enhanced in SLC25A3-deleted mitochondria, and further study of IDH2 sites targeted by both acetylation and malonylation revealed that these modifications can have site-specific and distinct functional effects. Finally, we uncovered a novel crosstalk between the two modifications, whereby mitochondrial energy dysfunction-induced acetylation of sirtuin 5 (SIRT5), inhibited its function. Because SIRT5 is a mitochondrial deacylase with demalonylase activity, this finding suggests that acetylation can modulate the malonylome. Together, our results position acylations as an arm of the mitochondrial response to energy dysfunction and suggest a mechanism by which focal disruption to the energy production machinery can have an expanded impact on global mitochondrial function.
    Keywords:  acetylation; acylations; energy; heart; mitochondria
  4. Front Physiol. 2021 ;12 707634
      Diabetic cardiomyopathy has been associated with mitochondrial damage. Mitochondria-endoplasmic reticulum (ER) contact is an important determinant of mitochondrial function and ER homeostasis. We therefore investigated whether hyperglycemia can damage the mitochondria by increasing their contact with the ER in cardiomyocytes. We found that hyperglycemia induced mitochondria-ER contact in cardiomyocytes, as evidenced by the increased MMM1, MDM34, and BAP31 expressions. Interestingly, the silencing of Mfn2 reduced the cooperation between the mitochondria and the ER in cardiomyocytes. Mfn2 silencing improved cardiomyocyte viability and function under hyperglycemic conditions. Additionally, the silencing of Mfn2 markedly attenuated the release of calcium from the ER to the mitochondria, thereby preserving mitochondrial metabolism in cardiomyocytes under hyperglycemic conditions. Mfn2 silencing reduced mitochondrial reactive oxygen species production, which reduced mitochondria-dependent apoptosis in hyperglycemia-treated cardiomyocytes. Finally, Mfn2 silencing attenuated ER stress in cardiomyocytes subjected to high-glucose stress. These results demonstrate that Mfn2 promotes mitochondria-ER contact in hyperglycemia-treated cardiomyocytes. The silencing of Mfn2 sustained mitochondrial function, suppressed mitochondrial calcium overload, prevented mitochondrial apoptosis, and reduced ER stress, thereby enhancing cardiomyocyte survival under hyperglycemic conditions.
    Keywords:  ER; Mfn2; apoptosis; mitochondria; mitochondria-ER contact
  5. EClinicalMedicine. 2021 Jun;36 100933
      Background: Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the composite of heart failure (HF) hospitalizations or cardiovascular mortality among patients with HF. However, the efficacy of SGLT2 inhibitors in secondary endpoints of randomized trials and in subgroups of HF patients is not well known.Methods: We performed a systematic review and meta-analysis of placebo-controlled, randomized trials of SGLT2 inhibitors in patients with HF. PubMed, Embase, and Cochrane databases were searched for trials published up to January 21, 2021. Data were extracted from published reports and quality assessment was performed per Cochrane recommendations. Hazard ratios (HRs) with 95% CI were pooled across trials. The primary endpoints of interest were all-cause and cardiovascular mortality.
    Results: Out of 3969 database results, 15 randomized trials and 20,241 patients were included; 10,594 (52·3%) received SGLT2 inhibitors. All-cause mortality (HR 0·86; 95% CI 0·79-0·94; p = 0·0007; I2=0%) and cardiovascular mortality (HR 0·86; 95% CI 0·78-0·96; p = 0·006; I2=0%) were significantly lower in patients treated with SGLT2 inhibitors compared with placebo. The composite of cardiovascular mortality, HF hospitalizations, or urgent visits for HF was significantly reduced with SGLT2 inhibitors in all the following subgroups: male, female, age < 65, age ≥ 65, race - Black and White, estimated glomerular filtration rate (eGFR) <60, eGFR ≥60, New York Heart Association (NYHA) class II, NYHA ≥III, and HF with preserved ejection fraction.
    Interpretation: In patients with HF, SGLT2 inhibitors significantly reduce all-cause and cardiovascular mortality compared with placebo. In addition, the composite of cardiovascular mortality or HF hospitalizations/urgent visits is reduced with SGLT2 inhibitors across subgroups of sex, age, race, eGFR, HF functional class, and ejection fraction.
    Keywords:  DM, diabetes mellitus; HF, heart failure; HFpEF, heart failure with preserved ejection fraction; HR, hazard ratio; Heart failure; LVEF, left ventricular ejection fraction; NYHA, New York Heart Association; OR, odds ratio; RCTs, randomized controlled trials; SGLT2 inhibitors; SGLT2, sodium-glucose cotransporter 2; Type 2 Diabetes; cardiovascular risk; eGFR, estimated glomerular filtration rate
  6. Nat Commun. 2021 07 28. 12(1): 4583
      Voltage dependent anion channel 2 (VDAC2) is an outer mitochondrial membrane porin known to play a significant role in apoptosis and calcium signaling. Abnormalities in calcium homeostasis often leads to electrical and contractile dysfunction and can cause dilated cardiomyopathy and heart failure. However, the specific role of VDAC2 in intracellular calcium dynamics and cardiac function is not well understood. To elucidate the role of VDAC2 in calcium homeostasis, we generated a cardiac ventricular myocyte-specific developmental deletion of Vdac2 in mice. Our results indicate that loss of VDAC2 in the myocardium causes severe impairment in excitation-contraction coupling by altering both intracellular and mitochondrial calcium signaling. We also observed adverse cardiac remodeling which progressed to severe cardiomyopathy and death. Reintroduction of VDAC2 in 6-week-old knock-out mice partially rescued the cardiomyopathy phenotype. Activation of VDAC2 by efsevin increased cardiac contractile force in a mouse model of pressure-overload induced heart failure. In conclusion, our findings demonstrate that VDAC2 plays a crucial role in cardiac function by influencing cellular calcium signaling. Through this unique role in cellular calcium dynamics and excitation-contraction coupling VDAC2 emerges as a plausible therapeutic target for heart failure.
  7. Am J Cardiovasc Dis. 2021 ;11(3): 262-272
      BACKGROUND: Sodium-glucose cotransporter 2 (SGLT2) inhibitors have shown promise in improving cardiovascular outcome in patients with heart failure (HF) and diabetes mellitus (DM). Although these benefits have been confirmed by several meta-analyses, small studies have not been included into these pooled analyses.AIM: Publication of recent RCTs prompted us to perform this updated meta-analysis to examine the consistency of favorable cardiovascular outcomes of SGLT2 inhibitors in HF patients by inclusion of clinical trials with small sample size.
    METHODS: We conducted a systematic review of the literature in PubMed/Medline and to identify all RCTs investigating the benefits of SGLT2 inhibitors in patients with HF. The primary endpoint of this meta-analysis was to compare the cardiovascular death (CVD) and hospitalization for HF (HHF) between patients who received an SGLT2 inhibitor and those who received a placebo or a non-SGLT2 inhibitor. We used a risk difference (RD) and log hazard ratio (HR) to pool the reported difference across the included RCTs.
    RESULTS: A total of 12 RCTs encompassing 59,825 patients at different stages of HF and DM were included, 32,448 patients in the SGLT2 inhibitor group and 27,377 patients in the control group. A pooled analysis of RCTs, regardless of HF severity or DM status, showed a significantly reduced RD for CVD (RD =-0.01, 95% CI [-0.01, 0.00], P=0.01) and HHF (RD =-0.02, 95% CI [-0.03, -0.01], P=0.0005) in patients who received a SGLT2 inhibitor compared to those who did not. A sub-group analysis showed a significantly reduced RD for CVD (RD =-0.01, 95% CI [-0.02, 0.00], P=0.03) and HHF (RD =-0.02, 95% CI [-0.03, 0.00], P=0.01) in patients with DM who received SGLT2 inhibitors regardless of the severity of HF. Also, regardless of DM status, RD for HHF favored the use of SGLT2 inhibitor than the control medication (RD =-0.05, 95% CI [-0.06, -0.03], P<0.00001).
    CONCLUSION: SGLT2 inhibitors have shown a promise in reducing CVD and HHF in patients with HF, regardless of ejection fraction or diabetes status.
    Keywords:  SGLT2 inhibitor; cardiovascular mortality; diabetes mellitus; heart failure; hospitalization for heart failure
  8. J Biol Chem. 2021 Jul 24. pii: S0021-9258(21)00807-3. [Epub ahead of print] 101005
      Barth syndrome (BTHS) is an X-linked disorder of mitochondrial phospholipid metabolism caused by pathogenic variants in the gene TAFFAZIN (TAZ), which results in abnormal cardiolipin (CL) content in the inner mitochondrial membrane. To identify unappreciated pathways of mitochondrial dysfunction in BTHS, we utilized an unbiased proteomics strategy and identified that complex I of the mitochondrial respiratory chain and the mitochondrial quality control protease PARL are altered in a new HEK293-based TAZ-deficiency model. Follow-up studies confirmed decreased steady state levels of specific complex I subunits and an assembly factor in the absence of TAZ; this decrease is in part based on decreased transcription, and results in reduced complex I assembly and function. PARL, a rhomboid protease associated with the inner mitochondrial membrane with a role in the mitochondrial response to stress such as mitochondrial membrane depolarization, is increased in TAZ-deficient cells. The increased abundance of PARL correlates with augmented processing of a downstream target, PGAM5, both at baseline and in response to mitochondrial depolarization. To clarify the relationship between abnormal CL content, complex I levels, and increased PARL expression that occurs when TAZ is missing, we used blue-native page and gene expression analysis to determine that these defects are remediated by SS-31 and bromoenol lactone, pharmacologic agents that bind CL or inhibit CL deacylation, respectively. These findings have the potential to enhance our understanding of the cardiac pathology of BTHS, where defective mitochondrial quality control and complex I dysfunction have well-recognized roles in the pathology of diverse forms of cardiac dysfunction.
    Keywords:  Barth Syndrome; Cardiolipin; Mitochondrial metabolism