Deregulation of mitochondrial functions provoked by long‐chain fatty acid accumulating in long‐chain 3‐hydroxyacyl‐CoA dehydrogenase and mitochondrial permeability transition deficiencies in rat heart – mitochondrial permeability transition pore opening as a potential contributing pathomechanism of cardiac alterations in these disorders

Abstract

Mitochondrial trifunctional protein and long‐chain 3‐hydroxyacyl‐CoA dehydrogenase deficiencies are fatty acid oxidation disorders biochemically characterized by tissue accumulation of long‐chain fatty acids and derivatives, including the monocarboxylic long‐chain 3‐hydroxy fatty acids (LCHFAs) 3‐hydroxytetradecanoic acid (3HTA) and 3‐hydroxypalmitic acid (3HPA). Patients commonly present severe cardiomyopathy for which the pathogenesis is still poorly established. We investigated the effects of 3HTA and 3HPA, the major metabolites accumulating in these disorders, on important parameters of mitochondrial homeostasis in Ca2+‐loaded heart mitochondria. 3HTA and 3HPA significantly decreased mitochondrial membrane potential, the matrix NAD(P)H pool and Ca2+ retention capacity, and also induced mitochondrial swelling. These fatty acids also provoked a marked decrease of ATP production reflecting severe energy dysfunction. Furthermore, 3HTA‐induced mitochondrial alterations were completely prevented by the classical mitochondrial permeability transition (mPT) inhibitors cyclosporin A and ADP, as well as by ruthenium red, a Ca2+ uptake blocker, indicating that LCHFAs induced Ca2+‐dependent mPT pore opening. Milder effects only achieved at higher doses of LCHFAs were observed in brain mitochondria, implying a higher vulnerability of heart to these fatty acids. By contrast, 3HTA and docosanoic acids did not change mitochondrial homeostasis, indicating selective effects for monocarboxylic LCHFAs. The present data indicate that the major LCHFAs accumulating in mitochondrial trifunctional protein and long‐chain 3‐hydroxyacyl‐CoA dehydrogenase deficiencies induce mPT pore opening, compromising Ca2+ homeostasis and oxidative phosphorylation more intensely in the heart. It is proposed that these pathomechanisms may contribute at least in part to the severe cardiac alterations characteristic of patients affected by these diseases.

Metabolite accumulation in VLCAD deficiency markedly disrupts mitochondrial bioenergetics and Ca2+ homeostasis in the heart

“…Mitochondria from the heart were prepared according to Ferranti et al [82] with some modifications [28], as well as from skeletal muscle in some experiments, as described previously [83]. The final pellet was resuspended in 10 mM Hepes buffer (pH 7.2) without EGTA containing 225 mM mannitol, 75 mM sucrose and 0.1% BSA (free fatty acid) (heart) or 10 mM Tris buffer (pH 7.4) containing 225 mM mannitol and 75 mM sucrose (skeletal muscle) at an approximate protein concentration of 15 mgÁmL À1 .…”

“…Noteworthy, morphological mitochondrial alterations in skeletal muscle detected by magnetic resonance imaging, as well as increased blood levels of creatine phosphokinase and lactic acid associated with episodic rhabdomyolysis, were found in VLCAD-deficient patients [23,24], suggesting a disturbance of mitochondrial energy homeostasis, although, to the best of our knowledge, ATP production was not measured in these patients. In addition, we previously demonstrated that long-chain hydroxylated fatty acids accumulating in long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency strongly disturb mitochondrial functions in various tissues [27][28][29]. In addition, we previously demonstrated that long-chain hydroxylated fatty acids accumulating in long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency strongly disturb mitochondrial functions in various tissues [27][28][29].…”

“…Similarly, there is evidence of bioenergetics disruption in the hearts of VLCAD-deficient mice, including a decrease in the phosphoreatine/ATP ratio [25], as well as the ATP pool [26], both associated with cardiac dysfunction in mice. In addition, we previously demonstrated that long-chain hydroxylated fatty acids accumulating in long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency strongly disturb mitochondrial functions in various tissues [27][28][29]. Therefore, in the present study, we investigated the effects of cis-5-tetradecenoic (Cis-5; C14:1) and myristic (Myr; C14) acids at physiological (≤ 10 lM) and pathological concentrations (30-100 lM) [30] on important endpoints of mitochondrial function, including membrane potential (DΨ m ), matrix NAD(P)H content, Ca 2+ retention capacity and ATP production in Ca 2+ -unloaded and loaded mitochondrial preparations from the hearts of juvenile rats.…”

Role of 3-Hydroxy Fatty Acid-Induced Hepatic Lipotoxicity in Acute Fatty Liver of Pregnancy

“…Biochemical hallmarks of LCHAD deficiency are the accumulation of long-chain 3-hydroxy fatty acids such as 3-hydroxy lauric acid, 3-hydroxy myristic acid, 3-hydroxy palmitic acid and 3-hydroxy dicarboxylic acid in the systemic circulation and increased excretion of 3-hydroxy dicarboxylic acids in the urine [ 53 , 54 , 55 ]. Several studies support the evidence for the accumulation of long-chain 3-hydroxy fatty acids (3-HFA) in patients with LCHAD deficiency and AFLP [ 53 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 ]. Children with the LCHAD deficiency are reported to develop sudden death with hypoglycemia, cardio-respiratory failure, acute cardiac failure and insufficiency, severe neonatal cardiomyopathy, hepatic dysfunction and acute liver failure, and skeletal myopathy with rhabdomyolysis [ 9 , 62 ].…”

Cyclophilin inhibition as a potential treatment for nonalcoholic steatohepatitis (NASH)

“…In vitro studies with CsA have reinforced findings from genetic knockout/knockdown by showing that cyclophilin inhibition can protect mitochondria from the kinds of metabolic disturbances that occur in NASH. For example, CsA blocked mPT in liver mitochondria following application of short-, medium-, and long-chain fatty acids or lysophosphatidylcholine [118][119][120][121]; blocked mPT and significantly reduced mitochondrial ROS, ATP depletion, and death of preadipocytes induced by high fatty acid concentrations [122]; blocked mPT and significantly reduced fructose-induced or high glucose-induced death of INS-1 pancreatic islet cells [123]; blocked mPT and restored the ATP deficit induced by long-chain fatty acids or palmitoyl-L-carnitine in cardiac mitochondria [124][125][126][127][128]; blocked mPT and prevented palmitate-induced insulin resistance in muscle mitochondria [107]; blocked hepatocyte death resulting from high glucose and hydrogen peroxide [129]; and alleviated fatty acid-induced ER stress gene induction, ROS elevation, and death of LO2 hepatocytes [60,130]. Düfer et al (2001), in contrast, found that CsA diminished glucose-induced insulin secretion of mouse pancreatic islets in vitro by inhibiting glucose-stimulated oscillations of the cytoplasmic free calcium concentration [131].…”