M. Tardieu

Cardiolipin content is involved in liver mitochondrial energy wasting associated with cancer-induced cachexia without the involvement of adenine nucleotide translocase

Cancer-induced cachexia describes the progressive skeletal muscle wasting associated with many cancers leading to shortened survival time in cancer patients. We previously reported that cardiolipin content and energy-wasting processes were both increased in liver mitochondria in a rat model of peritoneal carcinosis (PC)-induced cachexia. To increase the understanding of the cellular biology of cancer cachexia, we investigated the involvement of adenine nucleotide translocator (ANT) in mitochondrial energy-wasting processes in liver mitochondria of PC and pair-fed control rats and its interactions with cardiolipin in isolated liver mitochondria from healthy rats exposed to cardiolipin-enriched liposomes. We showed in this study that functional ANT content was decreased in liver mitochondria from PC rats but without any effects on the efficiency of ATP synthesis. Moreover, non-phosphorylating energy wasting was not affected by saturating concentrations of carboxyatractylate (CAT), a potent inhibitor of ANT, in liver mitochondria from PC rats. Decreased efficiency of ATP synthesis was found in normal liver mitochondria exposed to cardiolipin-enriched liposomes, with increased non-phosphorylating energy wasting, thus mimicking mitochondria from PC rats. However, the functional ANT content in these cardiolipin-enriched mitochondria was unchanged, although non-phosphorylating energy wasting was reduced by CAT-induced inhibition of ANT. Finally, non-phosphorylating energy wasting was increased in cardiolipin-enriched mitochondria with substrates for complexes 1 and 2, but not for complex 4. In conclusion, increased energy wasting measured in liver mitochondria from rats with cancer cachexia is dependent on cardiolipin but independent of ANT. Interactions between ANT and cardiolipin are modified when cancer cachexia occurs.

Signes néonatals des maladies héréditaires du métabolisme

Inborn metabolic diseases (IMDs) that can start in the neonatal period include various defects in numerous metabolic pathways. Such diseases are due to the genetic deficiency of an enzyme or a transporter. From a physiopathological point of view, the metabolic disorders can be divided into 3 diagnostically useful groups of diseases. The first group is due to the accumulation of endogenous toxic metabolites and includes inborn errors of amino acid metabolism, organic acidemias, urea cycle disorders, and sugar intolerances. The second one includes IMDs of intermediary metabolism causing a disturbance in energy production or utilization resulting from a defect in the liver, the muscles, the myocardium, or the brain (fatty acid oxidation defects, congenital lactic acidosis, etc.). The third group includes diseases that disturb the synthesis or the catabolism of complex molecules (lysosomal or peroxisomal disorders, etc.). IMDs are individually rare, but collectively numerous. Therefore, it is difficult to acquire extensive experience in the management of these diseases. However, the neonate has a limited repertoire of responses to severe illness and, at first, presents with nonspecific symptoms that could be easily attributed to infection or some other common cause. An IMD must be suspected in all situations of neonatal distress for which there is no apparent reason and that does not respond to symptomatic therapy. The priority is given to IMDs that are amenable to treatment, and emergency management has to be scheduled as soon as the diagnosis is suspected, even if the precise diagnosis is still unknown. In fact, emergency treatment must be undertaken in parallel with metabolic investigations, to prevent any delay in the management of the disease. The neonatologist must be able to recognize the neonatal distresses that suggest the possibility of an IMD. In such situations, an adequate diagnostic approach can be based on the proper use of only a few screening tests, which will also be useful to schedule adequate emergency treatment.

Long-term liver disease in methylmalonic and propionic acidemias

BACKGROUND AND OBJECTIVES Patients affected with methylmalonic acidemia (MMA) and propionic acidemia (PA) exhibit diverse long-term complications and poor outcome. Liver disease is not a reported complication. The aim of this study was to characterize and extensively evaluate long-term liver involvement in MMA and PA patients. PATIENTS AND METHODS We first describe four patients who had severe liver involvement during the course of their disease. Histology showed fibrosis and/or cirrhosis in 3 patients. Such liver involvement led us to retrospectively collect liver (clinical, laboratory and ultrasound) data of MMA (N = 12) or PA patients (N = 16) from 2003 to 2016. RESULTS Alpha-fetoprotein (αFP) levels were increased in 8/16 and 3/12 PA and MMA patients, respectively, and tended to increase with age. Moderate and recurrent increase of GGT was observed in 4/16 PA patients and 4/12 MMA patients. Abnormal liver ultrasound with either hepatomegaly and/or hyperechoic liver was observed in 7/9 PA patients and 3/9 MMA patients. CONCLUSIONS These data demonstrate that approximately half of the patients affected by MMA or PA had signs of liver abnormalities. The increase of αFP with age suggests progressive toxicity, which might be due to the metabolites accumulated in PA and MMA. These metabolites (e.g., methylmalonic acid and propionic acid derivatives) have previously been reported to have mitochondrial toxicity; this toxicity is confirmed by the results of histological and biochemical mitochondrial analyses of the liver in two of our MMA patients. In contrast to the moderate clinical, laboratory or ultrasound expression, severe pathological expression was found for three of the 4 patients who underwent liver biopsy, ranging from fibrosis to cirrhosis. These results emphasize the need for detailed liver function evaluation in organic aciduria patients, including liver biopsy when liver disease is suspected. TAKE HOME MESSAGE MMA and PA patients exhibit long-term liver abnormalities.

Pharmacological inhibition of carnitine palmitoyltransferase 1 restores mitochondrial oxidative phosphorylation in human trifunctional protein deficient fibroblasts

BACKGROUND Mitochondrial Trifunctional Protein deficiency (TFPD) is a severe genetic disease characterized by altered energy metabolism and accumulation of long-chain (LC) acylcarnitines in blood and tissues. This accumulation could impair the mitochondrial oxidative phosphorylation (OxPhos), contributing to the non-optimal outcome despite conventional diet therapy with medium-chain triglycerides (MCT). METHOD Acylcarnitine and OxPhos parameters were measured in TFPD-fibroblasts obtained from 8 children and cultured in medium mimicking fasting (LCFA) or conventional treatment (MCT), with or without Etomoxir (ETX) an inhibitor of carnitine palmitoyltransferase 1 (CPT1) activity, and were compared to results obtained with fibroblasts from 5 healthy-control children. The effects of various acylcarnitines were also tested on control fibroblasts. RESULTS In the LCFA-condition, TFPD-fibroblasts demonstrated a large accumulation of LC-acylcarnitines associated with decreased O2-consumption (63±3% of control, P<0.001) and ATP production (67±5%, P<0.001) without modification of coupling efficiency. A dose-dependent decrease in O2-consumption was reproduced in control fibroblasts by addition of increasing dose of LC-acylcarnitines, while it was almost preserved with MC-acylcarnitines. The MCT-condition reduced LC-acylcarnitine accumulation and partially improved O2-consumption (80±3%, P<0.01) in TFPD-fibroblasts. The addition of ETX in both LCFA- and MCT-conditions normalized acylcarnitine profiles and restored O2-consumption and ATP production at the same levels than control. CONCLUSION Accumulation of LC-acylcarnitines plays a major role in the pathophysiology of TFPD, reducing OxPhos capacities. These deleterious effects could be partially prevented by MCT-therapy and totally corrected by ETX. Inhibition of CPT1 may be view as a new therapeutic target for patients with a severe form of TFPD.

Case Definition of Encephalitis May Misdiagnose Congenital Urea Cycle Disorders

TO THE EDITOR—We read with interest the recent article by Venkatesan et al [1], which proposes a consensus guideline of the International Encephalitis Consortium for case definition and diagnostic algorithms in encephalitis. The authors define encephalitis as inflammation of the brain parenchyma associated with neurologic dysfunction, diagnosed on the basis of selected clinical, laboratory, electroencephalographic, and neuroimaging features. Confirmed encephalitis or encephalopathy of presumed infectious or autoimmune etiology requires 1 major criterion (altered mental status) and 3 or more minor criteria (fever, seizures and new onset of focal neurologic findings, cerebral spinal fluid pleocytosis, abnormality on neuroimaging or electroencephalography consistent with encephalitis). In our experience, late-onset inborn urea cycle disorders (UCDs) often mimic encephalitis [2, 3], and determination of blood ammonia level must be added to the initial routine screening for encephalitis. UCDs are inborn errors of nitrogen detoxification that cause hyperammonemia, astrocyte swelling, and brain edema. They are probably underdiagnosed, and their prevalence may exceed the current estimates of from 1 in 8000 to 1 in 44 000 births [4]. In late-onset forms, the first recognized clinical episode may be delayed for months or years, even until adulthood, after a prolonged symptomfree period. Hyperammonemic crises are frequently triggered by catabolic events such as infectious diseases [5, 6] and are often misdiagnosed as encephalitis. Within a few days, most patients develop a decreased level of consciousness associated with acute neurological signs, such as tremors and status epilepticus, vomiting, and fever [2, 6, 7]. Electroencephalogram classically shows bilateral slow delta waves and is frequently interpreted as suspicious for encephalitis [2, 3]. Neuroimaging findings are variable, from no abnormality to varying degrees of white matter injury without specific localization, basal ganglia hyperintensity, and multifocal edema, most often consistent with encephalitis. All findings could be symmetric or asymmetric, sometimes mimicking the finding of herpes simplex encephalitis [8]. Magnetic resonance spectroscopy may be discriminant, showing increased peaks of glutamine and glutamate, 2 toxic molecules that are involved in the physiopathology of brain injury in UCDs; however, this investigation is not commonly performed. Cerebrospinal fluid examination is usually normal, but pleocytosis has been reported in some cases [3]. Finally, the clinical presentation of late-onset UCD patients is usually in accordance with the definition of “encephalitis” reported by Venkatesan et al. However, acute hyperammonemic crises need specific therapies, and prognosis has been clearly improved by new treatments that involve the use of alternative pathways of nitrogen excretion. Thus, prompt recognition of a UCD and initiation without delay of specific therapies result in survival in the majority of late-onset patients [9]. In contrast, delayed initial diagnosis may adversely affect the outcome, with a highmortality rate [6]. Additionally, misdiagnosing a congenital disorder may have deleterious consequences for the patient and family. For these reasons, we think that determination of plasma ammonia level, which is a simple test that can be performed anywhere, should be added to the initial routine screening for encephalitis and may improve case definition and prognosis. Note

SFP CO-09 - L’allaitement maternel dans la phénylcétonurie

Objectifs La phenylcetonurie (PCU) necessite un regime et un equilibre metabolique tres stricts, ce qui peut etre un frein au maintien de l’allaitement maternel (AM). Nous rapportons la frequence et les effets sur le controle metabolique et la croissance de l’AM dans la PCU. Sujet / materiels et methodes Tous les nouveau-nes diagnostiques dans le Grand Ouest pour une PCU entre 2000 et 2012 et ayant beneficie d’un AM de plus d’un mois ont ete apparies retrospectivement avec un patient PCU controle en allaitement artificiel (AA) et suivis jusqu’a 3 ans. Resultats principaux 19 patients PCU sur 67 ont beneficie d’un AM. La frequence de l’AM dans la PCU etait tres inferieure a la moyenne regionale (28% vs 63%, p Conclusion Le diagnostic de PCU reste un frein a l’utilisation de l’AM alors que ce dernier permet un equilibre metabolique aussi bon qu’avec un AA. L’AM doit etre preconise en raison de ses effets benefiques sur le long terme.

SFRP CO-02 – Effets des dérivés des acides gras à chaîne longue sur l’énergétique mitochondriale

Objectif Etudier l’effet des derives des acides gras a chaine longue (AGCL) sur l’activite de la chaine respiratoire. Methode La production energetique de la chaine respiratoire a ete mesuree par oxygraphie sur des fibroblastes de patients avec deficit de b-oxydation des AGCL (LCHAD) cultives dans diverses conditions et comparee a des fibroblastes controles (CTRL). Les derives des AGCL ont ete estimes par le profil des acylcarnitines cellulaires. Resultats Les fibroblastes LCHAD avaient une accumulation d’acylcarnitines a chaine longue par rapport aux CTRL. En condition de production d’ATP (etat 3), leur consommation d’oxygene (- 48±18%, p Conclusion L’accumulation de derives des AGCL s’accompagnait d’une alteration reversible de la phosphorylation oxydative dans des fibroblastes LCHAD. Ce mecanisme pourrait jouer un role toxique majeur dans les decompensations des deficits de b-oxydation des AGCL.

SFP P-104 - Une leucodystrophie congénitale peu commune… La trypanosomiase africaine !

Objectif Decrire l’atteinte neurologique de la trypanosomiase africaine congenitale. Sujets Un garcon de 14 mois, ne en France et pas de voyage, presentait une hypotonie axiale severe evoluant depuis plusieurs mois, avec dystonie, anisocorie et fievre oscillante. L’IRM cerebrale montrait une leucodystrophie sus et sous-tentorielle bilaterale avec hypersignal des noyaux gris centraux. La recherche d’une encephalite virale et d’une leucodystrophie genetique etaient negatives. Sa mere d’origine Congolaise etait hospitalisee pour des troubles psychiatriques associant un ralentissement psychomoteur, une confusion et une anorexie. Son IRM montrait une leucodystrophie etendue semblable a celle de son fils. La ponction lombaire realisee chez l’enfant revelait la presence de trypanosoma brucei , en faveur d’une trypanosomiase africaine avec transmission materno-foetale. Un traitement antiparasitaire specifique a permis une amelioration clinique et radiologique partielle chez la mere et son enfant. Conclusion La trypanosomiase africaine est rare en France mais letale et sa transmission maternofoetale est exceptionnelle. La phase tardive associe une regression psychomotrice avec leucodystrophie etendue. Le traitement specifique permet la survie mais doit etre precoce.