Publications by authors named "Juan Manuel Chao de la Barca"

41 Publications

Achieving Expert-Level Interpretation of Serum Protein Electrophoresis through Deep Learning Driven by Human Reasoning.

Clin Chem 2021 Sep 7. Epub 2021 Sep 7.

Laboratoire de Biochimie et Biologie Moléculaire, Centre Hospitalier Universitaire d'Angers, Angers, France.

Background: Serum protein electrophoresis (SPE) is a common clinical laboratory test, mainly indicated for the diagnosis and follow-up of monoclonal gammopathies. A time-consuming and potentially subjective human expertise is required for SPE analysis to detect possible pitfalls and to provide a clinically relevant interpretation.

Methods: An expert-annotated SPE dataset of 159 969 entries was used to develop SPECTR (serum protein electrophoresis computer-assisted recognition), a deep learning-based artificial intelligence, which analyzes and interprets raw SPE curves produced by an analytical system into text comments that can be used by practitioners. It was designed following academic recommendations for SPE interpretation, using a transparent architecture avoiding the "black box" effect. SPECTR was validated on an external, independent cohort of 70 362 SPEs and challenged by a panel of 9 independent experts from other hospital centers.

Results: SPECTR was able to identify accurately both quantitative abnormalities (r ≥ 0.98 for fractions quantification) and qualitative abnormalities [receiver operating characteristic-area under curve (ROC-AUC) ≥ 0.90 for M-spikes, restricted heterogeneity of immunoglobulins, and beta-gamma bridging]. Furthermore, it showed highly accurate at both detecting (ROC-AUC ≥ 0.99) and quantifying (r = 0.99) M-spikes. It proved highly reproducible and resilient to minor variations and its agreement with human experts was higher (κ = 0.632) than experts between each other (κ = 0.624).

Conclusions: SPECTR is an algorithm based on artificial intelligence suitable to high-throughput SPEs analyses and interpretation. It aims at improving SPE reproducibility and reliability. It is freely available in open access through an online tool providing fully editable validation assistance for SPE.
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http://dx.doi.org/10.1093/clinchem/hvab133DOI Listing
September 2021

Tear metabolomics highlights new potential biomarkers for differentiating between Sjögren's syndrome and other causes of dry eye.

Ocul Surf 2021 Jul 28;22:110-116. Epub 2021 Jul 28.

Mitolab, MitoVasc Institute, CNRS, 6015, INSERM U1083, University of Angers, France; Department of Biochemistry and Molecular Biology, University Hospital, Angers, France.

Purpose: The lacrimal exocrinopathy of primary Sjögren's syndrome (pSS) is one of the main causes of severe dry eye syndrome and a burden for patients. Early recognition and treatment could prevent irreversible damage to lacrimal glands. The aim of this study was to find biomarkers in tears, using metabolomics and data mining approaches, in patients with newly-diagnosed pSS compared to other causes of dry eye syndrome.

Methods: A prospective cohort of 40 pSS and 40 non-pSS Sicca patients with dryness was explored through a standardized targeted metabolomic approach using liquid chromatography coupled with mass spectrometry. A metabolomic signature predictive of the pSS status was sought out using linear (logistic regression with elastic-net regularization) and non-linear (random forests) machine learning architectures, after splitting the studied population into training, validation and test sets.

Results: Among the 104 metabolites accurately measured in tears, we identified a discriminant signature composed of nine metabolites (two amino acids: serine, aspartate; one biogenic amine: dopamine; six lipids: Lysophosphatidylcholine C16:1, C18:1, C18:2, sphingomyelin C16:0 and C22:3, and the phoshatidylcholine diacyl PCaa C42:4), with robust performances (ROC-AUC = 0.83) for predicting the pSS status. Adjustment for age, sex and anti-SSA antibodies did not disrupt the link between the metabolomic signature and the pSS status. The non-lipidic components also remained specific for pSS regardless of the dryness severity.

Conclusion: Our results reveal a metabolomic signature for tears that distinguishes pSS from other dry eye syndromes and further highlight nine key metabolites of potential interest for early diagnosis and therapeutics of pSS.
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http://dx.doi.org/10.1016/j.jtos.2021.07.006DOI Listing
July 2021

Metabolomic Sexual Dimorphism of the Mouse Brain is Predominantly Abolished by Gonadectomy with a Higher Impact on Females.

J Proteome Res 2021 05 14;20(5):2772-2779. Epub 2021 Apr 14.

Département de Biochimie et Génétique, Centre Hospitalier Universitaire, 49933 Angers, France.

The importance of sexual dimorphism of the mouse brain metabolome was recently highlighted, in addition to a high regional specificity found between the frontal cortex, the cerebellum, and the brain stem. To address the origin of this dimorphism, we performed gonadectomy on both sexes, followed by a metabolomic study targeting 188 metabolites in the three brain regions. While sham controls, which underwent the same surgical procedure without gonadectomy, reproduced the regional sexual dimorphism of the metabolome previously identified, no sex difference was identifiable after gonadectomy, through both univariate and multivariate analyses. These experiments also made it possible to identify which sex was responsible for the dimorphism for 35 metabolites. The female sex contributed to the difference for more than 80% of them. Our results show that gonads are the main contributors to the brain sexual dimorphism previously observed, especially in females.
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http://dx.doi.org/10.1021/acs.jproteome.1c00045DOI Listing
May 2021

Ocular growth and metabolomics are dependent upon the spectral content of ambient white light.

Sci Rep 2021 Apr 7;11(1):7586. Epub 2021 Apr 7.

Singapore Eye Research Institute, Singapore, Singapore.

Myopia results from an excessive axial growth of the eye, causing abnormal projection of remote images in front of the retina. Without adequate interventions, myopia is forecasted to affect 50% of the world population by 2050. Exposure to outdoor light plays a critical role in preventing myopia in children, possibly through the brightness and blue-shifted spectral composition of sunlight, which lacks in artificial indoor lighting. Here, we evaluated the impact of moderate levels of ambient standard white (SW: 233.1 lux, 3900 K) and blue-enriched white (BEW: 223.8 lux, 9700 K) lights on ocular growth and metabolomics in a chicken-model of form-deprivation myopia. Compared to SW light, BEW light decreased aberrant ocular axial elongation and accelerated recovery from form-deprivation. Furthermore, the metabolomic profiles in the vitreous and retinas of recovering form-deprived eyes were distinct from control eyes and were dependent on the spectral content of ambient light. For instance, exposure to BEW light was associated with deep lipid remodeling and metabolic changes related to energy production, cell proliferation, collagen turnover and nitric oxide metabolism. This study provides new insight on light-dependent modulations in ocular growth and metabolomics. If replicable in humans, our findings open new potential avenues for spectrally-tailored light-therapy strategies for myopia.
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http://dx.doi.org/10.1038/s41598-021-87201-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8026599PMC
April 2021

Preliminary Metabolomic Profiling of the Vitreous Humor from Hypothermia Fatalities.

J Proteome Res 2021 05 5;20(5):2390-2396. Epub 2021 Apr 5.

Centre Universitaire Romand de Médecine Légale, Hôpital Universitaire de Lausanne, 1000 Lausanne 25, Switzerland.

The postmortem diagnosis of hypothermia fatalities is often complex due to the absence of pathognomonic lesions and biomarkers. In this study, potential novel biomarkers of hypothermia fatalities were searched in the vitreous humor of known cases of hypothermia fatalities ( = 20) compared to control cases ( = 16), using a targeted metabolomics approach allowing quantitative detection of 188 metabolites. A robust discriminant model with good predictivity was obtained with the supervised OPLS-DA multivariate analysis, showing a distinct separation between the hypothermia and control groups. This signature was characterized by the decreased concentrations of five metabolites (methionine sulfoxide, tryptophan, phenylalanine, alanine, and ornithine) and the increased concentration of 28 metabolites (21 phosphatidylcholines, 3 sphingomyelins, spermine, citrulline, acetylcarnitine, and hydroxybutyrylcarnitine) in hypothermia fatalities compared to controls. The signature shows similarities with already identified features in serum such as the altered concentrations of tryptophan, acylcarnitines, and unsaturated phosphatidylcholines, revealing a highly significant increased activity of methionine sulfoxide reductase, attested by a low methionine sulfoxide-to-methionine ratio. Our results show a preliminary metabolomics signature of hypothermia fatalities in the vitreous humor, highlighting an increased methionine sulfoxide reductase activity.
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http://dx.doi.org/10.1021/acs.jproteome.0c00901DOI Listing
May 2021

DRP1 haploinsufficiency attenuates cardiac ischemia/reperfusion injuries.

PLoS One 2021 25;16(3):e0248554. Epub 2021 Mar 25.

Institut MITOVASC, CNRS UMR 6015 INSERM U1083, Université d'Angers, Angers, France.

Mitochondrial dynamics is a possible modulator of myocardial ischemia/reperfusion injuries (IRI). We previously reported that mice partially deficient in the fusion protein OPA1 exhibited higher IRI. Therefore, we investigated whether deficiency in the fission protein DRP1 encoded by Dnm1l gene would affect IRI in Dnm1l+/- mouse. After baseline characterization of the Dnm1l+/- mice heart, using echocardiography, electron microscopy, and oxygraphy, 3-month-old Dnm1l+/- and wild type (WT) mice were exposed to myocardial ischemia/reperfusion (I/R). The ischemic area-at-risk (AAR) and area of necrosis (AN) were delimited, and the infarct size was expressed by AN/AAR. Proteins involved in mitochondrial dynamics and autophagy were analyzed before and after I/R. Mitochondrial permeability transition pore (mPTP) opening sensitivity was assessed after I/R. Heart weight and left ventricular function were not significantly different in 3-, 6- and 12-month-old Dnm1l+/- mice than in WT. The cardiac DRP1 protein expression levels were 60% lower, whereas mitochondrial area and lipid degradation were significantly higher in Dnm1l+/- mice than in WT, though mitochondrial respiratory parameters and mPTP opening did not significantly differ. Following I/R, the infarct size was significantly smaller in Dnm1l+/- mice than in WT (34.6±3.1% vs. 44.5±3.3%, respectively; p<0.05) and the autophagic markers, LC3 II and P62 were significantly increased compared to baseline condition in Dnm1l+/- mice only. Altogether, data indicates that increasing fusion by means of Dnm1l deficiency was associated with protection against IRI, without alteration in cardiac or mitochondrial functions at basal conditions. This protection mechanism due to DRP1 haploinsufficiency increases the expression of autophagic markers.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0248554PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7993837PMC
March 2021

A plasma metabolomic signature of Leber hereditary optic neuropathy showing taurine and nicotinamide deficiencies.

Hum Mol Genet 2021 03;30(1):21-29

Unité Mixte de Recherche (UMR) MITOVASC, Centre National de la Recherche Scientifique (CNRS) 6015, Institut National de la Santé et de la Recherche Médicale (INSERM) U1083, Université d'Angers, 49933 Angers, France.

Leber's hereditary optic neuropathy (LHON) is the most common disorder due to mitochondrial DNA mutations and complex I deficiency. It is characterized by an acute vision loss, generally in young adults, with a higher penetrance in males. How complex I dysfunction induces the peculiar LHON clinical presentation remains an unanswered question. To gain an insight into this question, we carried out a non-targeted metabolomic investigation using the plasma of 18 LHON patients, during the chronic phase of the disease, comparing them to 18 healthy controls. A total of 500 metabolites were screened of which 156 were accurately detected. A supervised Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) highlighted a robust model for disease prediction with a Q2 (cum) of 55.5%, with a reliable performance during the permutation test (cross-validation analysis of variance, P-value = 5.02284e-05) and a good prediction of a test set (P = 0.05). This model highlighted 10 metabolites with variable importance in the projection (VIP) > 0.8. Univariate analyses revealed nine discriminating metabolites, six of which were the same as those found in the Orthogonal Projections to Latent Structures Discriminant Analysis model. In total, the 13 discriminating metabolites identified underlining dietary metabolites (nicotinamide, taurine, choline, 1-methylhistidine and hippurate), mitochondrial energetic substrates (acetoacetate, glutamate and fumarate) and purine metabolism (inosine). The decreased concentration of taurine and nicotinamide (vitamin B3) suggest interesting therapeutic targets, given their neuroprotective roles that have already been demonstrated for retinal ganglion cells. Our results show a reliable predictive metabolomic signature in the plasma of LHON patients and highlighted taurine and nicotinamide deficiencies.
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http://dx.doi.org/10.1093/hmg/ddab013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8033144PMC
March 2021

Metabolomic signature of the seminal plasma in men with severe oligoasthenospermia.

Andrology 2020 11 31;8(6):1859-1866. Epub 2020 Aug 31.

Unité Mixte de Recherche MITOVASC, Centre National de la Recherche Scientifique (CNRS) 6015, Institut National de la Santé et de la Recherche Médicale (INSERM) U1083, Université d'Angers, Angers, France.

Background: Male factor is incriminated in approximately 50% of cases of infertility. The metabolomic approach has recently been used in the assessment of sperm quality and male fertility.

Materials And Methods: We analyzed the metabolomic signatures of the seminal plasma in 20 men with severe oligoasthenospermia (prewash total motile sperm count < 5.10 ) (SOA) and compared it to 20 men with normal semen parameters, with a standardized approach of targeted and quantitative metabolomics using high-performance liquid chromatography, coupled with tandem mass spectrometry, and the Biocrates Absolute IDQ p180 kit.

Results: Among the 188 metabolites analyzed, 110 were accurately measured in the seminal plasma. A robust model discriminating the two populations (Q = 55.2%) was obtained by OPLS-DA (orthogonal partial least-squares discriminant analysis), based on the drop in concentrations of 37 metabolites with a VIP (variable important for projection) greater than 1. Overall, in men with SOA, there was a significant decrease in: 17 phosphatidylcholines and four sphingomyelins; acylcarnitines, with free L-carnitine being the most discriminating metabolite; polyunsaturated fatty acids; six amino acids (glutamate, aspartate, methionine, tryptophan, proline, and alanine); and four biogenic amines (spermine, spermidine, serotonin, and alpha-aminoadipate).

Discussion: Our signature includes several metabolic changes with different impacts on the sperm quality: a change in phospholipid composition and the saturation of their fatty acids that is potentially linked to the deterioration of sperm membranes; a carnitine deficiency that can negatively impact the energy production via fatty acid oxidation and oxidative phosphorylation; and a decreased level of amino acids and biogenic amines that can lead to dysregulated metabolic and signaling pathways.

Conclusion: We provide a global overview of the metabolic defects contributing to the structural and functional alteration of spermatozoa in severe oligoasthenospermia. These findings offer new insights into the pathophysiology of male factor infertility that could help to develop future specific treatments.
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http://dx.doi.org/10.1111/andr.12882DOI Listing
November 2020

Metabolomic Profiling of Plasma and Erythrocytes in Sickle Mice Points to Altered Nociceptive Pathways.

Cells 2020 05 26;9(6). Epub 2020 May 26.

Département de Biochimie et Génétique, Centre Hospitalier Universitaire, 49933 Angers, France.

Few data-driven metabolomic approaches have been reported in sickle cell disease (SCD) to date. We performed a metabo-lipidomic study on the plasma and red blood cells of a steady-state mouse model carrying the homozygous human hemoglobin SS, compared with AS and AA genotypes. Among the 188 metabolites analyzed by a targeted quantitative metabolomic approach, 153 and 129 metabolites were accurately measured in the plasma and red blood cells, respectively. Unsupervised PCAs (principal component analyses) gave good spontaneous discrimination between HbSS and controls, and supervised OPLS-DAs (orthogonal partial least squares-discriminant analyses) provided highly discriminant models. These models confirmed the well-known deregulation of nitric oxide synthesis in the HbSS genotype, involving arginine deficiency and increased levels of dimethylarginines, ornithine, and polyamines. Other discriminant metabolites were newly evidenced, such as hexoses, alpha-aminoadipate, serotonin, kynurenine, and amino acids, pointing to a glycolytic shift and to the alteration of metabolites known to be involved in nociceptive pathways. Sharp remodeling of lysophosphatidylcholines, phosphatidylcholines, and sphingomyelins was evidenced in red blood cells. Our metabolomic study provides an overview of the metabolic remodeling induced by the sickle genotype in the plasma and red blood cells, revealing a biological fingerprint of altered nitric oxide, bioenergetics and nociceptive pathways.
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http://dx.doi.org/10.3390/cells9061334DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7349104PMC
May 2020

Sexual Dimorphism of Metabolomic Profile in Arterial Hypertension.

Sci Rep 2020 05 5;10(1):7517. Epub 2020 May 5.

Departement de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.

Metabolomic studies have demonstrated the existence of biological signatures in blood of patients with arterial hypertension, but no study has hitherto reported the sexual dimorphism of these signatures. We compared the plasma metabolomic profiles of 28 individuals (13 women and 15 men) with essential arterial hypertension with those of a healthy control group (18 women and 18 men), using targeted metabolomics. Among the 188 metabolites explored, 152 were accurately measured. Supervised OPLS-DA (orthogonal partial least squares-discriminant analysis) showed good predictive performance for hypertension in both sexes (Qcum = 0.59 in women and 0.60 in men) with low risk of overfitting (p-value-CV ANOVA = 0.004 in women and men). Seventy-five and 65 discriminant metabolites with a VIP (variable importance for the projection) greater than 1 were evidenced in women and men, respectively. Both sexes showed a considerable increase in phosphatidylcholines, a decrease in C16:0 with an increase in C28:1 lysophosphatidylcholines, an increase in sphingomyelins, as well as an increase of symmetric dimethylarginine (SDMA), acetyl-ornithine and hydroxyproline. Twenty-nine metabolites, involved in phospholipidic and cardiac remodeling, arginine/nitric oxide pathway and antihypertensive and insulin resistance mechanisms, discriminated the metabolic sexual dimorphism of hypertension. Our results highlight the importance of sexual dimorphism in arterial hypertension.
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http://dx.doi.org/10.1038/s41598-020-64329-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7200712PMC
May 2020

Elevated Levels of Monocyte Chemotactic Protein-1 in the Follicular Fluid Reveals Different Populations among Women with Severe Endometriosis.

J Clin Med 2020 May 1;9(5). Epub 2020 May 1.

Unité Mixte de Recherche MITOVASC, équipe Mitolab, Centre National de la Recherche Scientifique 6015, Institut National de la Santé et de la Recherche Médicale U1083, Université d'Angers, 49000 Angers, France.

To determine if a modification of the cytokine profile occurs in the follicular fluid (FF) of women with endometriosis undergoing in vitro fertilization (IVF), we performed a prospective observational study from January 2018 to February 2019. In total, 87 women undergoing IVF were included: 43 for severe endometriosis-related infertility and 40 controls with other causes of infertility. The cytokine profile of the FF was determined by multiplex fluorescent-bead-based technology allowing the measurement of 59 cytokines. Monocyte Chemoattractant Protein 1 (MCP-1) was the only variable retained in the multivariate analysis. We identified two subgroups of patients in the endometriosis group: MCP-1-low group ( = 23), which had FF MCP-1 levels comparable to the control group, and MCP-1-high ( = 20), which had significantly higher FF levels. Only patients in the MCP-1-high group had a significantly altered cytokine profile in the FF, and had a significantly higher serum estradiol level ( = 0.002) and a significantly lower number of oocytes recovered ( = 0.01) compared to the MCP-1-low and the control group. Our study has shown an alteration of the oocyte microenvironment in women with endometriosis associated with high follicular fluid levels of MCP-1, allowing the identification of a subgroup of endometriosis patients with a potentially worse prognosis.
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http://dx.doi.org/10.3390/jcm9051306DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7291127PMC
May 2020

Sickle Cell Disease: Metabolomic Profiles of Vaso-Occlusive Crisis in Plasma and Erythrocytes.

J Clin Med 2020 Apr 11;9(4). Epub 2020 Apr 11.

Département de Biochimie et Génétique, Centre Hospitalier Universitaire, 49933 Angers, France.

The metabolomic profile of vaso-occlusive crisis, compared to the basal state of sickle cell disease, has never been reported to our knowledge. Using a standardized targeted metabolomic approach, performed on plasma and erythrocyte fractions, we compared these two states of the disease in the same group of 40 patients. Among the 188 metabolites analyzed, 153 were accurately measured in plasma and 143 in red blood cells. Supervised paired partial least squares discriminant analysis (pPLS-DA) showed good predictive performance for test sets with median area under the receiver operating characteristic (AUROC) curves of 99% and mean p-values of 0.0005 and 0.0002 in plasma and erythrocytes, respectively. A total of 63 metabolites allowed discrimination between the two groups in the plasma, whereas 61 allowed discrimination in the erythrocytes. Overall, this signature points to altered arginine and nitric oxide metabolism, pain pathophysiology, hypoxia and energetic crisis, and membrane remodeling of red blood cells. It also revealed the alteration of metabolite concentrations that had not been previously associated with sickle cell disease. Our results demonstrate that the vaso-occlusive crisis has a specific metabolomic signature, distinct from that observed at steady state, which may be potentially helpful for finding predictive biomarkers for this acute life-threatening episode.
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http://dx.doi.org/10.3390/jcm9041092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7230294PMC
April 2020

Metabolomics hallmarks OPA1 variants correlating with their in vitro phenotype and predicting clinical severity.

Hum Mol Genet 2020 05;29(8):1319-1329

Department of Pharmacy and Biotechnology (FABIT), University of Bologna, 40126 Bologna, Italy.

Interpretation of variants of uncertain significance is an actual major challenge. We addressed this question on a set of OPA1 missense variants responsible for variable severity of neurological impairments. We used targeted metabolomics to explore the different signatures of OPA1 variants expressed in Opa1 deleted mouse embryonic fibroblasts (Opa1-/- MEFs), grown under selective conditions. Multivariate analyses of data discriminated Opa1+/+ from Opa1-/- MEFs metabolic signatures and classified OPA1 variants according to their in vitro severity. Indeed, the mild p.I382M hypomorphic variant was segregating close to the wild-type allele, while the most severe p.R445H variant was close to Opa1-/- MEFs, and the p.D603H and p.G439V alleles, responsible for isolated and syndromic presentations, respectively, were intermediary between the p.I382M and the p.R445H variants. The most discriminant metabolic features were hydroxyproline, the spermine/spermidine ratio, amino acid pool and several phospholipids, emphasizing proteostasis, endoplasmic reticulum (ER) stress and phospholipid remodeling as the main mechanisms ranking OPA1 allele impacts on metabolism. These results demonstrate the high resolving power of metabolomics in hierarchizing OPA1 missense mutations by their in vitro severity, fitting clinical expressivity. This suggests that our methodological approach can be used to discriminate the pathological significance of variants in genes responsible for other rare metabolic diseases and may be instrumental to select possible compounds eligible for supplementation treatment.
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http://dx.doi.org/10.1093/hmg/ddaa047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7254852PMC
May 2020

[Multiparametric biochemical analysis revealing an increase of homocysteinemia and NT-proBNP in hypertensive patients living in Bamako (Mali)].

Pan Afr Med J 2020 13;35:10. Epub 2020 Jan 13.

Faculté de Pharmacie, Université des Sciences, des Techniques et des Technologies de Bamako, Mali.

Introduction: Arterial hypertension is a major public health problem in sub-Saharan Africa due to its high frequency and to the cardiovascular risk that it entails. The purpose of this study was to assess the prevalence of clinical and biological risk factors of hypertension in Bamako (Mali).

Methods: We conducted a case-control study, stratified in function of the sex, of 72 participants including 36 patients with hypertension and 36 controls. Twenty-two plasma biochemical parameters have been measured and analyzed using univariate and multivariate tests.

Results: Hyperhomocysteinemia was found in 55.6% of women (p = 0.03) and 100% of men (p = 0.007) with hypertension. High NT-proBNP was also found in 16.7% of women (VIP > 1 in multivariate model) and of men with hypertension (p = 0.00006). A good multivariate predictive model (OPLS-DA) was only obtained in women with high blood pressure, with Qcum = 0.73, attesting severe sexual dimorphism associated with arterial hypertension. This model involved eight parameters whose plasma concentration was modified (homocysteine, NT-proBNP, potassium, urea, blood glucose, sodium, chlorine and total proteins).

Conclusion: We registered a significant association between hyperhomocysteinemia and arterial hypertension. Therefore, the assay of homocysteine associated with good management would decrease the risk of cardiovascular diseases while improving the quality of life of hypertensive patients.
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http://dx.doi.org/10.11604/pamj.2020.35.10.18821DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7026517PMC
March 2020

The cytokine profile of follicular fluid changes during ovarian ageing.

J Gynecol Obstet Hum Reprod 2020 Apr 3;49(4):101704. Epub 2020 Feb 3.

Reproductive Biology Unit, Angers University Hospital, 49000, Angers, France; MITOVASC Institute, CNRS 6015, INSERM U1083, Angers University, 49000, Angers, France.

Objective: Ovarian ageing is one of the commonest causes of infertility in patients consulting for assisted reproductive technology. The composition of the follicular fluid (FF), which reflects the exchanges between the oocyte and its microenvironment, has been extensively investigated to determine the metabolic pathways involved in various ovarian disorders. Considering the importance of cytokines in folliculogenesis, we focused on the cytokine profile of the FF during ovarian ageing.

Material And Methods: Our cross-sectional study assesses the levels of 27 cytokines and growth factors in the FF of two groups of women undergoing in vitro fertilization. One group included 28 patients with ovarian ageing clinically characterized by a diminished ovarian reserve (DOR), and the other group included 29 patients with a normal ovarian reserve (NOR), serving as controls.

Results: With univariate analysis, the cytokine profile was found to differ significantly between the two groups. After adjustment of the p-values, platelet-derived growth factor-BB (PDGF-BB) was the only cytokine with a significantly lower concentration in the DOR group (7.34 ± 16.11 pg/mL) than in the NOR group (24.39 ± 41.38 pg/mL) (p = 0.005), independently of chronological age.

Conclusion: Thus, PDGF-BB would seem to be implicated in the physiopathology of DOR, potentially in relation to its role in folliculogenesis or in the protection against oxidative stress.
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http://dx.doi.org/10.1016/j.jogoh.2020.101704DOI Listing
April 2020

Data-Mining Approach on Transcriptomics and Methylomics Placental Analysis Highlights Genes in Fetal Growth Restriction.

Front Genet 2019 9;10:1292. Epub 2020 Jan 9.

Unité Mixte de Recherche (UMR) MITOVASC, Équipe Mitolab, Centre National de la Recherche Scientifique (CNRS) 6015, Institut National de la Santé et de la Recherche Médicale (INSERM) U1083, Université d'Angers, Angers, France.

Intrauterine Growth Restriction (IUGR) affects 8% of newborns and increases morbidity and mortality for the offspring even during later stages of life. Single omics studies have evidenced epigenetic, genetic, and metabolic alterations in IUGR, but pathogenic mechanisms as a whole are not being fully understood. An in-depth strategy combining methylomics and transcriptomics analyses was performed on 36 placenta samples in a case-control study. Data-mining algorithms were used to combine the analysis of more than 1,200 genes found to be significantly expressed and/or methylated. We used an automated text-mining approach, using the bulk textual gene annotations of the discriminant genes. Machine learning models were then used to explore the phenotypic subgroups (premature birth, birth weight, and head circumference) associated with IUGR. Gene annotation clustering highlighted the alteration of cell signaling and proliferation, cytoskeleton and cellular structures, oxidative stress, protein turnover, muscle development, energy, and lipid metabolism with insulin resistance. Machine learning models showed a high capacity for predicting the sub-phenotypes associated with IUGR, allowing a better description of the IUGR pathophysiology as well as key genes involved.
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http://dx.doi.org/10.3389/fgene.2019.01292DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6962302PMC
January 2020

Tryptophane-kynurenine pathway in the remote ischemic conditioning mechanism.

Basic Res Cardiol 2020 01 10;115(2):13. Epub 2020 Jan 10.

Institut Mitovasc, UMR CNRS 6015, INSERM U1083, CHU d'Angers, Université d'Angers, Angers, France.

The actual protective mechanisms underlying cardioprotection with remote ischemic conditioning (RIC) remain unclear. Recent data suggest that RIC induces kynurenine (KYN) and kynurenic acid synthesis, two metabolites derived from tryptophan (TRP), yet a causal relation between TRP pathway and RIC remains to be established. We sought to study the impact of RIC on the levels of TRP and its main metabolites within tissues, and to assess whether blocking kynurenine (KYN) synthesis from TRP would inhibit RIC-induced cardioprotection. In rats exposed to 40-min coronary occlusion and 2-h reperfusion, infarct size was significantly smaller in RIC-treated animals (35.7 ± 3.0% vs. 46.5 ± 2.2%, p = 0.01). This protection was lost in rats that received 1-methyl-tryptophan (1-MT) pretreatment, an inhibitor of KYN synthesis from TRP (infarct size = 46.2 ± 5.0%). Levels of TRP and nine compounds spanning its metabolism through the serotonin and KYN pathways were measured by reversed-phase liquid chromatography-tandem mass spectrometry in the liver, heart, and limb skeletal muscle, either exposed or not to RIC. In the liver, RIC induced a significant increase in xanthurenic acid, nicotinic acid, and TRP. Likewise, RIC increased NAD-dependent deacetylase sirtuin activity in the liver. Pretreatment with 1-MT suppressed the RIC-induced increases in NAD-dependent deacetylase sirtuin activity. Altogether, these findings indicate that RIC mechanism is dependent on TRP-KYN pathway activation.
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http://dx.doi.org/10.1007/s00395-019-0770-xDOI Listing
January 2020

Metabolomics shows no impairment of the microenvironment of the cumulus-oocyte complex in women with isolated endometriosis.

Reprod Biomed Online 2019 Dec 12;39(6):885-892. Epub 2019 Aug 12.

Department of Reproductive Medicine, Angers University Hospital, Angers 49000, France; MITOVASC Institute, CNRS 6015, INSERM U1083, Angers University, Angers 49000, France; Reproductive Biology Unit, Angers University Hospital, Angers 49000, France.

Research Question: Is there any metabolomic evidence of impairment of the cumulus-oocyte complex (COC) microenvironment in the follicular fluid of women with endometriosis?

Design: A prospective observational study from January to July 2018 at the Angers University Hospital, France. Seventy-nine women undergoing IVF with or without intracytoplasmic sperm injection (ICSI) were included: 39 for endometriosis-related infertility and 40 controls with other causes of infertility. A targeted quantitative metabolomic and lipidomic analysis was performed.

Results: Patient characteristics (age, body mass index, smoking status, hormonal profile and ovarian reserve markers) were comparable between the endometriosis and the control groups. There was no significant difference in the cumulative FSH dose used for stimulation between the endometriosis and the control groups (2732 versus 2257 IU, respectively). There were no differences in the oocyte maturity rates (72.2% versus 77.7%), or in the fertilization rates in IVF and ICSI (49.4% versus 50.2% and 76.4% versus 68.8%, respectively) between the endometriosis and control groups. Among the 188 metabolites analysed, 150 were accurately measured. Univariate analysis did not reveal any significant modification of metabolite concentrations, and none of the multivariate models discriminated between the two groups of patients, even when the study was restricted to the most severe form of endometriosis.

Conclusions: No specific metabolomic signature of endometriosis was found in the follicular fluid of women undergoing IVF. These results suggest that there is no microenvironmental impairment of the COC in cases of isolated endometriosis among women with infertility.
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http://dx.doi.org/10.1016/j.rbmo.2019.08.001DOI Listing
December 2019

Metabolomics reveals highly regional specificity of cerebral sexual dimorphism in mice.

Prog Neurobiol 2020 01 23;184:101698. Epub 2019 Sep 23.

Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, France; Equipe Mitolab, Unité Mixte de Recherche MITOVASC, CNRS 6015, INSERM U1083, Université d'Angers, Angers, France. Electronic address:

The development of personalized medicine according to gender calls for the integration of sexual dimorphism in pre-clinical models of diseases. Although sexual dimorphism in the brain of the mouse has been the subject of several behavioral, neuroimaging and experimental studies, very few have characterized the bases of sexual dimorphism in the brain on the omics scale. In particular, physiological variations in metabolomic and lipidomic terms related to gender have not been mapped in the brain. We carried out a metabolomic analysis, targeting 188 metabolites representative of various cellular structures and metabolisms, in three brain regions: frontal cortex, brain stem and cerebellum, in 3-month-old C57BL-6 J male (n = 20) vs. female (n = 20) mice. Our results demonstrate the existence of sexual dimorphism in the whole brain as well as in separate brain regions. Half of the 129 accurately measured metabolites were involved in the sexual dimorphism of the murine brain, but only 8% of those (hydroxyproline, creatinine, hexoses, tryptophan, threonine and lysoPC.a.C18.2) were involved in common in the three cerebral regions, while 71%, including phosphatidylcholines, lysophosphatidylcholines, sphingomyelins, acylcarnitines, amino acids, biogenic amines, and polyamines, were specific to only one region of the brain, underscoring the highly regional specificity of cerebral sexual dimorphism in mice.
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http://dx.doi.org/10.1016/j.pneurobio.2019.101698DOI Listing
January 2020

Lipidomics Reveals Triacylglycerol Accumulation Due to Impaired Fatty Acid Flux in Opa1-Disrupted Fibroblasts.

J Proteome Res 2019 07 14;18(7):2779-2790. Epub 2019 Jun 14.

Equipe Mitolab, Institut MITOVASC, CNRS 6015, INSERM U1083 , Université d'Angers , 49933 Angers , France.

OPA1 is a dynamin GTPase implicated in mitochondrial membrane fusion. Despite its involvement in lipid remodeling, the function of OPA1 has never been analyzed by whole-cell lipidomics. We used a nontargeted, reversed-phase lipidomics approach, validated for cell cultures, to investigate OPA1-inactivated mouse embryonic fibroblasts ( Opa1 MEFs). This led to the identification of a wide range of 14 different lipid subclasses comprising 212 accurately detected lipids. Multivariate and univariate statistical analyses were then carried out to assess the differences between the Opa1 and Opa1 genotypes. Of the 212 lipids identified, 69 were found to discriminate between Opa1 MEFs and Opa1 MEFs. Among these lipids, 34 were triglycerides, all of which were at higher levels in Opa1 MEFs with fold changes ranging from 3.60 to 17.93. Cell imaging with labeled fatty acids revealed a sharp alteration of the fatty acid flux with a reduced mitochondrial uptake. The other 35 discriminating lipids included phosphatidylcholines, lysophosphatidylcholines, phosphatidylethanolamine, and sphingomyelins, mainly involved in membrane remodeling, and ceramides, gangliosides, and phosphatidylinositols, mainly involved in apoptotic cell signaling. Our results show that the inactivation of OPA1 severely affects the mitochondrial uptake of fatty acids and lipids through membrane remodeling and apoptotic cell signaling.
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http://dx.doi.org/10.1021/acs.jproteome.9b00081DOI Listing
July 2019

Nicotinamide Deficiency in Primary Open-Angle Glaucoma.

Invest Ophthalmol Vis Sci 2019 06;60(7):2509-2514

Equipe Mitolab, Unité Mixte de Recherche MITOVASC, CNRS 6015, INSERM U1083, Université d'Angers, Angers, France.

Purpose: To investigate the plasma concentration of nicotinamide in primary open-angle glaucoma (POAG).

Methods: Plasma of 34 POAG individuals was compared to that of 30 age- and sex-matched controls using a semiquantitative method based on liquid chromatography coupled to high-resolution mass spectrometry. Subsequently, an independent quantitative method, based on liquid chromatography coupled to mass spectrometry, was used to assess nicotinamide concentration in the plasma from the same initial cohort and from a replicative cohort of 20 POAG individuals and 15 controls.

Results: Using the semiquantitative method, the plasma nicotinamide concentration was significantly lower in the initial cohort of POAG individuals compared to controls and further confirmed in the same cohort, using the targeted quantitative method, with mean concentrations of 0.14 μM (median: 0.12 μM; range, 0.06-0.28 μM) in the POAG group (-30%; P = 0.022) and 0.19 μM (median: 0.18 μM; range, 0.08-0.47 μM) in the control group. The quantitative dosage also disclosed a significantly lower plasma nicotinamide concentration (-33%; P = 0.011) in the replicative cohort with mean concentrations of 0.14 μM (median: 0.14 μM; range, 0.09-0.25 μM) in the POAG group, and 0.19 μM (median: 0.21 μM; range, 0.09-0.26 μM) in the control group.

Conclusions: Glaucoma is associated with lower plasmatic nicotinamide levels, compared to controls, suggesting that nicotinamide supplementation might become a future therapeutic strategy. Further studies are needed, in larger cohorts, to confirm these preliminary findings.
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http://dx.doi.org/10.1167/iovs.19-27099DOI Listing
June 2019

Effects of sildenafil on maximum walking time in patients with arterial claudication: The ARTERIOFIL study.

Vascul Pharmacol 2019 Jul - Aug;118-119:106563. Epub 2019 May 30.

Univ Rennes, CHU Rennes, INSERM CIC1414, Vascular Medicine Unit, F-35000 Rennes, France.

Background: Patients with lower extremity peripheral artery disease (PAD) frequently experience claudication, a clinical symptom indicative of reduced walking capacity. Recommended care consists of exercise rehabilitation combined with optimal medical treatment and surgery. The effects of a single oral dose of sildenafil, a phosphodiesterase type-5 inhibitor, on patients with claudication are discussed. The aim of this study was to test the efficacy of a single 100 mg dose of sildenafil compared to placebo in terms of maximal walking time (MWT) in patients with claudication.

Methods: The ARTERIOFIL study is a crossover, double-blind, prospective, randomized, single-center study conducted at Angers University Hospital in France. MWT (primary endpoint) was assessed using a treadmill test (10% incline; 3.2 km/h). Secondary endpoints (pain-free walking time (PFWT), transcutaneous oximetry during exercise and redox cycle parameters and safety) were also studied.

Results: Fourteen patients were included of whom two were ultimately excluded. In the 12 remaining patients, the MWT was significantly improved during the sildenafil period compared with the placebo period (300 s [95% CI 172 s-428 s] vs 402 s [95% CI 274 s-529 s] p < 0.01). Sildenafil had no significant effect on pain-free walking time or skin tissue oxygenation during exercise. According to redox cycle parameters, sildenafil significantly reduced blood glucose and pyruvate levels and the 3-hydroxybutyrate/acetoacetate ratio, while there was no significant effect on lactate, 3-hydroxybutyrate, acetoacetate and free fatty acid levels. Symptomatic transient hypotension was observed in two women.

Conclusions: The ARTERIOFIL study has shown that a single 100 mg oral dose of sildenafil had a significant effect on increase in MWT but had no significant effects on PFWT and oxygenation parameters in patients with claudication. A double-blind, prospective, randomized, multicenter study (VIRTUOSE©) is ongoing to evaluate the chronic effect of six month-long sildenafil treatment on MWT in PAD patients with claudication.

Clinical Trial Registration: This clinical trial was registered at clinicaltrials.gov, registration. number: NCT02832570, (https://clinicaltrials.gov/ct2/show/NCT02832570).
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http://dx.doi.org/10.1016/j.vph.2019.05.003DOI Listing
May 2020

The Metabolomic Signature of Opa1 Deficiency in Rat Primary Cortical Neurons Shows Aspartate/Glutamate Depletion and Phospholipids Remodeling.

Sci Rep 2019 04 15;9(1):6107. Epub 2019 Apr 15.

Equipe Mitolab, Institut MITOVASC, CNRS 6015, INSERM U1083, Université d'Angers, Angers, France.

Pathogenic variants of OPA1, which encodes a dynamin GTPase involved in mitochondrial fusion, are responsible for a spectrum of neurological disorders sharing optic nerve atrophy and visual impairment. To gain insight on OPA1 neuronal specificity, we performed targeted metabolomics on rat cortical neurons with OPA1 expression inhibited by RNA interference. Of the 103 metabolites accurately measured, univariate analysis including the Benjamini-Hochberg correction revealed 6 significantly different metabolites in OPA1 down-regulated neurons, with aspartate being the most significant (p < 0.001). Supervised multivariate analysis by OPLS-DA yielded a model with good predictive capability (Q = 0.65) and a low risk of over-fitting (permQ2 = -0.16, CV-ANOVA p-value 0.036). Amongst the 46 metabolites contributing the most to the metabolic signature were aspartate, glutamate and threonine, which all decreased in OPA1 down-regulated neurons, and lysine, 4 sphingomyelins, 4 lysophosphatidylcholines and 32 phosphatidylcholines which were increased. The phospholipid signature may reflect intracellular membrane remodeling due to loss of mitochondrial fusion and/or lipid droplet accumulation. Aspartate and glutamate deficiency, also found in the plasma of OPA1 patients, is likely the consequence of respiratory chain deficiency, whereas the glutamate decrease could contribute to the synaptic dysfunction that we previously identified in this model.
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http://dx.doi.org/10.1038/s41598-019-42554-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6465244PMC
April 2019

Metabolomic Profiling of Aqueous Humor in Glaucoma Points to Taurine and Spermine Deficiency: Findings from the Eye-D Study.

J Proteome Res 2019 03 11;18(3):1307-1315. Epub 2019 Feb 11.

Unité Mixte de Recherche MITOVASC, équipe Mitolab, Centre National de la Recherche Scientifique 6015, Institut National de la Santé et de la Recherche Médicale U1083 , Université d'Angers , Angers 49035 , France.

We compared the metabolomic profile of aqueous humor from patients with primary open-angle glaucoma (POAG; n = 26) with that of a group of age- and sex-matched non-POAG controls (n = 26), all participants undergoing cataract surgery. Supervised paired partial least-squares discriminant analysis showed good predictive performance for test sets with a median area under the receiver operating characteristic of 0.89 and a p-value of 0.0087. Twenty-three metabolites allowed discrimination between the two groups. Univariate analysis after the Benjamini-Hochberg correction showed significant differences for 13 of these metabolites. The POAG metabolomic signature indicated reduced concentrations of taurine and spermine and increased concentrations of creatinine, carnitine, three short-chain acylcarnitines, 7 amino acids (glutamine, glycine, alanine, leucine, isoleucine, hydroxyl-proline, and acetyl-ornithine), 7 phosphatidylcholines, one lysophosphatidylcholine, and one sphingomyelin. This suggests an alteration of metabolites involved in osmoprotection (taurine and creatinine), neuroprotection (spermine, taurine, and carnitine), amino acid metabolism (7 amino acids and three acylcarnitines), and the remodeling of cell membranes drained by the aqueous humor (hydroxyproline and phospholipids). Five of these metabolic alterations, already reported in POAG plasma, concern spermine, C3 and C4 acylcarnitines, PC aa 34:2, and PC aa 36:4, thus highlighting their importance in the pathogenesis of glaucoma.
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http://dx.doi.org/10.1021/acs.jproteome.8b00915DOI Listing
March 2019

Metabolomics signatures of a subset of RET variants according to their oncogenic risk level.

Endocr Relat Cancer 2019 03;26(3):379-389

Département de Biochimie et Génétique, CHU d'Angers, Angers, France.

Thirty percent of medullary thyroid carcinomas (MTCs) are related to dominant germline pathogenic variants in the RET proto-oncogene. According to their aggressiveness, these pathogenic variants are classified in three risk levels: 'moderate', 'high' and 'highest'. The present study compares the metabolomics profiles of five pathogenic variants, whether already classified or not. We have generated six stable murine fibroblast cell lines (NIH3T3) expressing the WT allele or variants of the human RET gene, with different levels of pathogenicity, including the M918V variant that is yet to be accurately classified. We carried out a targeted metabolomics study of the cell extracts with a QTRAP mass spectrometer, using the Biocrates Absolute IDQ p180 kit, which allows the quantification of 188 endogenous molecules. The data were then subjected to multivariate statistical analysis. One hundred seventy three metabolites were accurately measured. The metabolic profiles of the cells expressing the RET variants were found to be correlated with their oncogenic risk. In addition, the statistical model we constructed for predicting the oncogenic risk attributed a moderate risk to the M918V variant. Our results indicate that metabolomics may be useful for characterizing the pathogenicity of the RET gene variants and their levels of aggressiveness.
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http://dx.doi.org/10.1530/ERC-18-0314DOI Listing
March 2019

Metabolomic Approach in STEMI-Patients Undergoing Left Ventricular Remodeling.

Int J Mol Sci 2019 01 12;20(2). Epub 2019 Jan 12.

Institut Mitovasc, University of Angers, University Hospital of Angers, 49000 Angers, France.

Left ventricular remodeling (LVR) occurring after ST-segment elevation myocardial infarction (STEMI) is frequent and severe. We present a metabolomic approach as an attempt to reveal unknown biomarkers associated with post-STEMI LVR. Out of 192 consecutive patients with successfully revascularized STEMI, 32 presented LVR and were clinically matched with 32 no-LVR patients. They underwent cardiac magnetic resonance at baseline, three months and 12 months. Blood samples were collected during index hospitalization. Creatine kinase (CK) peak and inflammatory markers were higher for LVR patients compared to no-LVR patients (mean 3466 ± 2211 and 2394 ± 1615 UI/L respectively, = 0.005 for CK peak; mean 35.9 ± 44.3 vs. 21.7 ± 30.4 mg/L respectively, = 0.020 for C-reactive protein). Leukocyte and neutrophil counts were also higher for LVR patients (mean 12028 ± 2593/mL vs. 10346 ± 3626/mL respectively, = 0.028 and mean 9035 ± 3036/mL vs. 7596 ± 3822/mL respectively, < 0.001). For metabolomic analysis, sphingomyelin C20:2 and symmetrical dimethylarginine were higher for LVR patients, but did not reach significance after the correction for the alpha risk. The metabolomic approach did not discriminate patients with and without LVR. However, common parameters that focus on infarction severity, such as infarct size and inflammatory markers, differed between the groups.
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http://dx.doi.org/10.3390/ijms20020289DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6358808PMC
January 2019

A serum metabolomics signature of hypothermia fatalities involving arginase activity, tryptophan content, and phosphatidylcholine saturation.

Int J Legal Med 2019 May 18;133(3):889-898. Epub 2018 Sep 18.

Centre Universitaire Romand de Médecine Légale, Hôpital Universitaire de Lausanne, Chemin de la Vuliette 4, 1000, Lausanne 25, Switzerland.

Introduction: Hypothermia is a potentially lethal condition whose postmortem diagnosis is often complex to perform due to the absence of pathognomonic lesions and biomarkers. Our first study of human serum and urinary metabolome in hypothermia fatalities sought novel biomarkers with better diagnostic performances than those already existing.

Material And Method: Thirty-two cases of hypothermia deaths and 16 cases excluding known antemortem exposure to cold or postmortem elements suggesting hypothermia were selected. A targeted metabolomic study allowing the detection and quantitation of 188 metabolites was performed on collected serum and urine using direct flow injection (FIA) and liquid chromatography (LC) separation, both coupled to tandem mass spectrometry (MS/MS). Amino acid quantification was also carried on using an in-house LC-MS/MS method in order to replicate the results obtained with the metabolomic study.

Results: A discriminant metabolic signature allowing a clear separation between hypothermia and control groups was obtained in the serum. This signature was characterized by increased arginase activity and fatty acid unsaturation along with decreased levels of tryptophan in hypothermia fatalities compared to controls. By contrast, no discriminant metabolic signature separating hypothermia from control fatalities was found in urines.

Discussion: The serum metabolic signature of hypothermia fatalities herein observed pointed toward metabolic adaptations that likely aimed at heat production enhancement, endothelial function, and cell membrane fluidity preservation. Novel biomarkers potentially useful in a hypothermia diagnosis were also identified.
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http://dx.doi.org/10.1007/s00414-018-1937-yDOI Listing
May 2019

A Metabolomics Profiling of Glaucoma Points to Mitochondrial Dysfunction, Senescence, and Polyamines Deficiency.

Invest Ophthalmol Vis Sci 2018 09;59(11):4355-4361

Equipe Mitolab, Institut Mitovasc, Centre National de la Recherche Scientifique 6015, Institut National de la Santé et de la Recherche Médicale (INSERM) U1083, Université d'Angers, Angers, France.

Purpose: To determine the plasma metabolomic signature of primary open-angle glaucoma (POAG).

Methods: We compared the metabolomic profiles of plasma from individuals with POAG (n = 36) with age- and sex-matched controls with cataract (n = 27). A targeted metabolomics study was performed using the standardized p180 Biocrates Absolute IDQ p180 kit with a QTRAP 5500 mass spectrometer. Multivariate analyses were performed using principal component analysis (PCA) and the least absolute shrinkage and selection operator (LASSO) method.

Results: Among the 151 metabolites accurately measured, combined univariate and multivariate analyses revealed 18 discriminant metabolites belonging to the carbohydrate, acyl-carnitine, phosphatidylcholine, amino acids, and polyamine families. The metabolomic signature of POAG points to three closely interdependent pathophysiologic conditions; that is, defective mitochondrial oxidation of energetic substrates, altered metabolism resembling that observed in senescence, and a deficiency in spermidine and spermine, both polyamines being involved in the protection of retinal ganglion cells.

Conclusions: Our results highlight a systemic and age-related mitochondrial defect in the pathogenesis of POAG.
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http://dx.doi.org/10.1167/iovs.18-24938DOI Listing
September 2018

The Metabolomic Bioenergetic Signature of Opa1-Disrupted Mouse Embryonic Fibroblasts Highlights Aspartate Deficiency.

Sci Rep 2018 08 1;8(1):11528. Epub 2018 Aug 1.

Equipe Mitolab, Institut MITOVASC, CNRS 6015, INSERM U1083, Université d'Angers, Angers, France.

OPA1 (Optic Atrophy 1) is a multi-isoform dynamin GTPase involved in the regulation of mitochondrial fusion and organization of the cristae structure of the mitochondrial inner membrane. Pathogenic OPA1 variants lead to a large spectrum of disorders associated with visual impairment due to optic nerve neuropathy. The aim of this study was to investigate the metabolomic consequences of complete OPA1 disruption in Opa1 mouse embryonic fibroblasts (MEFs) compared to their Opa1 counterparts. Our non-targeted metabolomics approach revealed significant modifications of the concentration of several mitochondrial substrates, i.e. a decrease of aspartate, glutamate and α-ketoglutaric acid, and an increase of asparagine, glutamine and adenosine-5'-monophosphate, all related to aspartate metabolism. The signature further highlighted the altered metabolism of nucleotides and NAD together with deficient mitochondrial bioenergetics, reflected by the decrease of creatine/creatine phosphate and pantothenic acid, and the increase in pyruvate and glutathione. Interestingly, we recently reported significant variations of five of these molecules, including aspartate and glutamate, in the plasma of individuals carrying pathogenic OPA1 variants. Our findings show that the disruption of OPA1 leads to a remodelling of bioenergetic pathways with the central role being played by aspartate and related metabolites.
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http://dx.doi.org/10.1038/s41598-018-29972-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6070520PMC
August 2018

Obesity-induced metabolic disturbance drives oxidative stress and complement activation in the retinal environment.

Mol Vis 2018 7;24:201-217. Epub 2018 Mar 7.

The John Curtin School of Medical Research, The Australian National University, Canberra, Australia.

Purpose: Systemic increases in reactive oxygen species, and their association with inflammation, have been proposed as an underlying mechanism linking obesity and age-related macular degeneration (AMD). Studies have found increased levels of oxidative stress biomarkers and inflammatory cytokines in obese individuals; however, the correlation between obesity and retinal inflammation has yet to be assessed. We used the leptin-deficient (ob/ob) mouse to further our understanding of the contribution of obesity to retinal oxidative stress and inflammation.

Methods: Retinas from ob/ob mice were compared to age-matched wild-type controls for retinal function (electroretinography) and gene expression analysis of retinal stress (), oxidative stress ( and ), and complement activation (, , , and ). Oxidative stress was further quantified using a reactive oxygen species and reactive nitrogen species (ROS and RNS) assay. Retinal microglia and macrophage migration to the outer retina and complement activation were determined using immunohistochemistry for IBA1 and C3, respectively. Retinas and sera were used for metabolomic analysis using QTRAP mass spectrometry.

Results: Retinal function was reduced in ob/ob mice, which correlated to changes in markers of retinal stress, oxidative stress, and inflammation. An increase in C3-expressing microglia and macrophages was detected in the outer retinas of the ob/ob mice, while gene expression studies showed increases in the complement activators ( and ) and a decrease in a complement regulator (). The expression of several metabolites were altered in the ob/ob mice compared to the controls, with changes in polyunsaturated fatty acids (PUFAs) and branched-chain amino acids (BCAAs) detected.

Conclusions: The results of this study indicate that oxidative stress, inflammation, complement activation, and lipid metabolites in the retinal environment are linked with obesity in ob/ob animals. Understanding the interplay between these components in the retina in obesity will help inform risk factor analysis for acquired retinal degenerations, including AMD.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5842320PMC
November 2018
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