Autophagy and Oncosis/Necroptosis Are Enhanced in Cardiomyocytes from Heart Failure Patients

Abstract

BackgroundAlthough originally described as a survival mechanism, it is unknown whether and to what extent autophagy is implicated in the terminal stages of heart failure. Here, we studied magnitude and evolution of autophagy in patients with intractable heart failure.Material/MethodsMyocardial samples were obtained from 22 patients with ischemic cardiomyopathy and idiopathic dilated cardiomyopathy who were undergoing cardiac transplantation. Hearts from 11 patients who died from non-cardiac causes were used as control samples. Autophagy was evaluated by immunostaining with a monoclonal microtubule associated protein light chain 3 (LC3)-II antibody, while the relationship of autophagy with apoptosis and oncosis was assessed by double staining with TUNEL (terminal deoxynucleotidyl transferase – mediated deoxyuridine triphosphate nick end labeling) assay and complement 9 (C9) immunological staining, respectively. In addition, several necroptotic markers, including RIP1 and RIP3 (receptor interacting protein kinase 1 and 3), anti-C3 (cleaved-caspase-3), and anti-NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) were assessed by immunohistochemistry.ResultsAnti-LC3-II staining was detected in 8.7±1.6% of the heart failure patient heart samples and in 1.2±0.3% of control patient heart samples. Vacuole formation started at one nuclear pole, before becoming bipolar and involving the cytosol. Subsequently, the autophagic process extended also to the nuclei, which underwent a progressive vacuolization and disintegration, assuming a peculiar “strawberry like appearance”. Myocytes with extensive vacuole formation exhibited nuclear degeneration, which was associated with TUNEL, C3, C9, RIP1, and RIP3 positive staining. Conversely, myocytes with less extensive vacuole formation showed RIP1 and NF-κB positive staining, though not positivity for other cell death markers.ConclusionsAutophagy was extensively detected in end-stage heart failure and its progression, resulted in secondary cell death, with occurrence of oncosis and necroptosis exceeding that of apoptosis. Conversely, activation of the RIP1/NF-κB pathway was associated with cell survival.

Cellular and Molecular Differences between HFpEF and HFrEF: A Step Ahead in an Improved Pathological Understanding

“…Lipid exposure has been shown to cause cardiomyocyte apoptosis in vitro [139]; however, current studies show conflicting evidence in vivo [140][141][142]. Recent evidence has suggested that cardiomyocyte autophagy and necroptosis (a controlled form of necrosis) play a larger role than apoptosis [143]. Interestingly, even low levels of cardiomyocyte apoptosis induce HFrEF in animal models [144].…”

Programmed Cell Death in the Left and Right Ventricle of the Late Phase of Post-Infarction Heart Failure

“…In recent years, knowledge on necroptosis has advanced and a practically unknown process has become a well-established pathophysiological factor contributing to myocardial damage in various types of HF [ 4 , 7 , 9 , 10 , 30 ]. In our previous study, we have shown the activation of canonical necroptosis signaling being implicated in both infarcted and non-infarcted LV areas of failing rat hearts, while its execution mechanisms were restricted to the former area only.…”

“…Such activation of necroptotic signaling has been suggested to be associated with myocardial fibrosis, ventricular remodeling, inflammation and severe contractile dysfunction [ 8 ]. Likewise, studies employing explanted human failing hearts of various etiologies have shown the participation of necroptosis in HF-associated myocardial deterioration [ 4 , 7 ]. Some of these studies have also investigated autophagy and reported contradictory data on necroptosis-autophagy link in the heart [ 4 , 7 , 44 ].…”

“…Understanding the mechanisms of cell death in heart failure (HF) after myocardial infarction (MI) is of great clinical importance, since the extent of cellular loss significantly determines the degree of cardiac injury, contractile dysfunction, adverse remodeling and finally patient prognosis [ 1 , 2 , 3 ]. Therefore, an enormous effort has been undertaken to elucidate the role of certain cell death modalities in HF, and current knowledge on autophagy [ 4 , 5 , 6 ] and necroptosis [ 4 , 7 , 8 , 9 , 10 ], commonly occurring in post-infarction HF [ 4 , 5 , 7 , 8 , 9 , 10 ], has been advanced.…”

“…In fact, some authors consider necroptosis as an upstream inhibitor of autophagic flux in cardiomyocytes, while others position autophagy upstream of RIP1-mediated necroptosis [ 32 , 35 ]. Recently, it has been reported in human HF that autophagy precedes necroptosis, at least in the terminal stage of this cardiac syndrome [ 4 ]. In an effort to expand the knowledge about a role of necroptosis and autophagy in the pathology of a late phase of post-infarction HF and to assess how they might be intertwined, we performed this comprehensive, descriptive study with a particular focus on the protein analysis of their signaling pathways.…”