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The HSP70 co-chaperone BAG3 targets unfolded proteins to degradation via chaperone assisted selective autophagy (CASA), thereby playing pivotal roles in the proteostasis of adult cardiomyocytes (CMs). However, the complex functions of BAG3 for regulating autophagy in cardiac disease are not completely understood. Here, we demonstrate that conditional inactivation of Bag3 in murine CMs leads to age-dependent dysregulation of autophagy, associated with progressive cardiomyopathy. Surprisingly, Bag3-deficient CMs show increased canonical and non-canonical autophagic flux in the juvenile period when first signs of cardiac dysfunction appear, but reduced autophagy during later stages of the disease. Juvenile Bag3-deficient CMs are characterized by decreased levels of soluble proteins involved in synchronous contraction of the heart, including the gap junction protein Connexin 43 (CX43). Reiterative administration of chloroquine (CQ), an inhibitor of canonical and non-canonical autophagy, but not inactivation of Atg5, restores normal concentrations of soluble cardiac proteins in juvenile Bag3-deficient CMs without an increase of detergent-insoluble proteins, leading to complete recovery of early-stage cardiac dysfunction in Bag3-deficient mice. We conclude that loss of Bag3 in CMs leads to age-dependent differences in autophagy and cardiac dysfunction. Increased non-canonical autophagic flux in the juvenile period removes soluble proteins involved in cardiac contraction, leading to early-stage cardiomyopathy, which is prevented by reiterative CQ treatment., Competing Interests: Conflicts of interest None declared., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Pharmacologic support of the failing neonatal heart to maintain cardiac output, which is vital for sufficient end organ perfusion, is a challenging task for the pediatric intensivist, especially since strategies which have been proven to be effective in adults cannot necessarily be extrapolated to neonates. The unique biochemical properties and structure of the neonatal heart, including the increased non-contractile tissue mass, a lower responsiveness to beta adrenergic agents and the heart rate dependent cardiac output with a limited ability to increase stroke volume, favor some of the new inotropes of the Ca+ sensitizer family. Focusing on the after load reduction, inodilators as phosphodiesterase inhibitors and human brain natriuretic peptide offer treatment options for the neonatal myocardium. Additionally, thyroxine and steroids have been investigated in neonates with low cardiac output after surgery for congenital heart disease. Gene therapy, in particular cardiac-selective gene transfer, might offer perspectives for future support for the neonatal heart. This text reviews some of the most recent pharmacologic strategies targeting the failing myocardium in the critically ill newborn and infant.

Aims: Left ventricular non-compaction (LVNC) is caused by mutations in multiple genes. It is still unclear whether LVNC is the primary determinant of cardiomyopathy or rather a secondary phenomenon with intrinsic cardiomyocyte dysfunction being the actual cause of the disease. Here, we describe a family with LVNC due to a novel missense mutation, pE96K, in the cardiac troponin T gene (TNNT2). [ABSTRACT FROM PUBLISHER]

DCM is the most common cardiomyopathy in childhood. Effectiveness of anticongestive therapy is limited in most cases and about one-third of children diagnosed with DCM die or receive heart transplantation within the first year after diagnosis. Cardiac stem cell transplantation has become a promising therapy to treat heart failure in adult patients. Based on these promising results, the cardiac stem cell therapy might also represent a new therapeutic option particularly in young children. The present case documents for the first time intracoronary administration of autologous bone marrow-derived progenitor cells in a critically ill two-yr-old child with severe heart failure caused by DCM. Because of progressive worsening of the clinical condition despite maximal anticongestive treatment, the decision to perform autologous stem cell therapy was made. Cardiac stem cell therapy proved to be technically feasible, was associated with improvement in cardiac function, and might represent an option before heart transplantation in children with severe heart failure. [ABSTRACT FROM AUTHOR]

Studies assessing the long-term outcome after heart transplantation HTX in patients with cardiomyopathy (CM) in the paediatric age range are rare. The aim of this study was to determine the survival rate of children with CM undergoing HTX and to analyse how aetiology of cardiomyopathy influenced morbidity and mortality. We retrospectively analysed the medical records of children; who were transplanted in our centre between June 1988 and October 2019. 236 heart transplantations were performed since 1988 (9 re-transplants). 98 of 227 patients (43.2%) were transplanted because of CM. Survival rates were 93% after 1; 84% after 10 and 75% after 30 years. Overall; the aetiology of CM could be clearly identified in 37 subjects (37.7%). This rate increased up to 66.6% (12/19) by applying a comprehensive diagnostic workup since 2016. The survival rate was lower (p < 0.05) and neurocognitive deficits were more frequent (p = 0.001) in subjects with systemic diseases than in individuals with cardiac-specific conditions. These data indicate that the long-term survival rate of children with CM after HTX in experienced centers is high. A comprehensive diagnostic workup allows unraveling the basic defect in the majority of patients with CM undergoing HTX. Aetiology of CM affects morbidity and mortality in subjects necessitating HTX. [ABSTRACT FROM AUTHOR]