Tryptophan metabolism in phenylketonuria: A French adult cohort study.

Many similarities between tryptophan (Trp) and phenylalanine (Phe) metabolisms exist. It is possible that a modification of Trp metabolism might be seen in phenylketonuria (PKU). As some of these metabolites have neuroactive properties, they should be consider in neurological impairment seen in this pathology and not totally explained by blood Phe concentrations. One hundred and fifty-one adult PKU patients (mean age 26.8 years) were included for this study. Plasma Trp, kynurenine (KYN), 3-hydroxykynurenic acid (3HK), and kynurenic acid (KA) were analyzed by liquid chromatography coupled with tandem mass spectrometry. KYN and 3HK were significantly lower in PKU patients compared to general population (P < .0001), and KA was significantly enhanced is this population (P = .009). Furthermore, 3HK concentration was significantly different between PKU patients underwent controlled low-Phe diet compared to PKU patients without this diet (P = .0016). In PKU patients with diet, taking AA substitute enable higher plasma 3HK concentration than without (P = .0008) but still not reaching general population level (P < .0001). Although further study has to be done, it is clear that Trp metabolism is modified in adult PKU patients. An exploration of complete Trp metabolism, and not only Trp concentration, is needed in PKU population, but also in other inborn error of metabolism treated with hypoprotidic diet.

Review of nutritional components in Covid-19: what about micronutrients? / Revue des facteurs nutritionnels dans la Covid-19 : qu'en est-il des micronutriments ?

Nutritional status is an important protection factor against viral infections. Both undernutrition and malnutrition cause deficits in micronutrients, trace elements and vitamins necessary for various physiological functions and the appropriate functioning of the immune system. These deficiencies and infectious diseases often coexist, with complex interactions. An assessment of the micro-nutrient nutritional status of Covid-19 patients has not been at the center of priorities and recommendations, due to both the medical emergency and the absence of direct evidence and rapid effects of supplementation. Few recommendations have come from learned societies due to the lack of significant evidence of the effects of supplementation in positive patients and a need for robust studies. Essential trace elements and vitamins are necessary for the differentiation, activation and execution of many functions of immune cells, but their specific role has yet to be defined. This review article discusses in the context of Covid-19 the importance of micronutrients (selenium, copper, zinc, vitamins C, D, A and those of group B) in the host to tend towards an optimization of the immune response to infections. A nutritional balance remains the key word for achieving micronutrient homeostasis. Attention had to be paid to micronutrients in primary prevention, in the general population, in order to reduce the risk of impaired nutritional status in case of major health situations.

Le statut nutritionnel est important pour protéger des infections virales. La dénutrition comme la malnutrition induisent des déficits en micronutriments, éléments-trace et vitamines nécessaires aux fonctions physiologiques et au fonctionnement du système immunitaire. Ces carences et les maladies infectieuses coexistent souvent en complexes interactions. Une évaluation de l'état nutritionnel en micronutriments des patients Covid-19 n'a pas été au centre des priorités face à l'urgence médicale et à l'absence de preuves directes et rapides des effets de supplémentation. Peu de recommandations ont émané des sociétés savantes par manque de preuves significatives des effets de supplémentations, avec une nécessité d'études robustes. S'il est reconnu que les oligo-éléments essentiels et les vitamines sont nécessaires à la différenciation, l'activation et l'exécution de fonctions des cellules immunitaires, leur rôle spécifique reste encore à définir. Cette synthèse aborde dans la Covid-19 l'importance des micronutriments (sélénium, cuivre, zinc, vitamines C, D, A et groupe B) chez l'hôte pour tendre vers une optimisation de la réponse immunitaire aux infections. En prévention primaire, en population générale, un équilibre nutritionnel reste central pour atteindre l'homéostasie des micronutriments, pour diminuer le risque des situations de déséquilibre et de fragilisation face à des situations sanitaires d'ampleur.

Simultaneous analysis of retinol, six carotenoids, two tocopherols, and coenzyme Q10 from human plasma by HPLC.

Lipophilic antioxidant determination is of relevance in health and diseases. Several HPLC methods exists but rare are those including coenzyme Q10 with carotenoids, retinol and tocopherols. Here a single-step extraction was proposed for the detection of retinol, α and γ-tocopherols, lutein, zeaxanthin, trans-ß-carotene, α-carotene, ß-cryptoxanthin and lycopene as well as coenzyme Q10. A single HPLC column was used and UV-vis diode array detection was performed. Echinenone, alpha-tocopherol nicotinate and coenzyme Q4 were employed as internal standards. Intra-assay and inter-assay precision were respectively 1.4-7.9% and 2.2-15.8%. Accuracy was validated using SRM 968e. LOD (limit of detection) and LOQ (limit of quantification) obtained were sufficient for nutritional epidemiological study and routine clinical application.

Dysregulation of tryptophan catabolism at the host-skin microbiota interface in hidradenitis suppurativa.

Hidradenitis suppurativa (HS) is a chronic skin disorder of unknown etiology that manifests as recurrent, painful lesions. Cutaneous dysbiosis and unresolved inflammation are hallmarks of active HS, but their origin and interplay remain unclear. Our metabolomic profiling of HS skin revealed an abnormal induction of the kynurenine pathway of tryptophan catabolism in dermal fibroblasts, correlating with the release of kynurenine pathway-inducing cytokines by inflammatory cell infiltrates. Notably, overactivation of the kynurenine pathway in lesional skin was associated with local and systemic depletion in tryptophan. Yet the skin microbiota normally degrades host tryptophan into indoles regulating tissue inflammation via engagement of the aryl hydrocarbon receptor (AHR). In HS skin lesions, we detected contextual defects in AHR activation coinciding with impaired production of bacteria-derived AHR agonists and decreased incidence of AHR ligand-producing bacteria in the resident flora. Dysregulation of tryptophan catabolism at the skin-microbiota interface thus provides a mechanism linking the immunological and microbiological features of HS lesions. In addition to revealing metabolic alterations in patients with HS, our study suggests that correcting AHR signaling would help restore immune homeostasis in HS skin.

[Tryptophan metabolism: utility of plasmatic assay in phenylketonuria, a study in 6 adult patients]. / Dosage sanguin des métabolites de la voie du tryptophane dans le suivi biologique des patients atteints de phénylcétonurie : étude chez 6 patients adultes et perspectives.

Phenylketonuria (PKU, OMIM 261600) is an autosomal recessive inborn error of metabolism caused by a deficiency of the hepatic enzyme phenylalanine hydroxylase (PAH; EC 1.14.16.1). If untreated, the disease leads to an important intellectual disability (IQ <50). Although many facts are common between phenylalanine (Phe) and tryptophan (Trp) metabolism, little is known about Trp metabolism modification in PKU. Our aim was to evaluate the modifications of Trp metabolism in a phenylketonuric population. A monocentric study was conducted between October 2016 and March 2017. Every phenylketonuric fasting adults were included during their annual follow up. For each patient, 9 analytes of Trp metabolism were quantified in peripheral blood using liquid chromatography coupled with tandem mass spectrometry. Mann and Whitney tests (p <0.05) were carried out in StatView 5.0 software. A total of 6 PKU patients were studied. Significant modification of Trp metabolism was shown. Indeed, three analytes, i.e. tryptophan, kynurenine and 3-hydroxykynurenic acid, were significantly lower in phenylketonuric than in healthy population (p-value <0.05), without known confounding factors. This study shows a significant modification of Trp metabolism in peripheral blood of phenylketonuric patients. Nevertheless, more investigations are necessary to confirm the modification of Trp metabolism in PKU and to determine how this metabolism is involved in neurological symptoms.

Simultaneous determination of tryptophan and 8 metabolites in human plasma by liquid chromatography/tandem mass spectrometry.

Tryptophan (Trp) is an essential amino-acid and the precursor of many biologically active substances such as kynurenine (KYN) and serotonin (5HT). Its metabolism is involved in different physiopathological states, such as cardiovascular diseases, cancer, immunomodulation or depression. Hence, the quantification of Trp catabolites, from both KYN and 5HT pathways, might be usefulfor the discovery of novel diagnostic and follow-up biomarkers. We have developed a simple method for quantification of Trp and 8 of its metabolites,involved in both KYN and 5HT pathways, using liquid chromatography coupled to tandem mass spectrometry. We also validated the methodin human plasma samples, according to NF EN ISO 15189 criteria. Our method shows acceptable intra- and inter-day coefficients of variation (CV) (<12% and <16% respectively). The linearity entirelycovers the human plasma range. Stabilities of whole blood and of residues weredetermined, as well as the use of 2 different types of collectiontube, enabling us to adapt our process. Matrix effects and reference values showed good agreement compared to the literature. We propose here a method allowing the simultaneous quantification of a panel of Trp catabolites, never used before to our knowledge. This method, witha quickchromatographic runtime (15min) and simple sample preparation, has beenvalidated according to NF EN ISO 15189 criteria. The method enables the detailed analysis of these metabolic pathways, which are thought to be involved in a number of pathological conditions.

[Development and analytical validation according COFRAC recommendations of pyruvate and ketone body assay on open automated analyser]. / Mise au point et validation en portée B selon les recommandations du Cofrac d'un dosage de pyruvate et de corps cétoniques sur un automate ouvert.

Measurements of pyruvate and ketones bodies (acetoacetate and 3-hydroxybutyrate) are essential to the investigation of intermediary metabolism. Indeed, their blood levels reflect energy balance influenced by nutritional status. This balance can be disturbed in certain diseases such as diabetes and some inherited metabolic disorders. We have developed methods for assays on open automated biochemistry analyser, Konelab 20 XT (ThermoFischer, Whaltham USA), using kits marketed by Sobioda (Montbonnot, France) for pyruvate and Wako Chemicals GmbH (Neuss, Germany) for ketones, on deproteinised blood sample. We have validated the performance of these three quantitative methods using NF EN ISO 15189 (range B) standard criteria. We obtain satisfactory results concerning fidelity (precision measured as within and between batch CVs are respectively less than 7% and less than 6%), measuring ranges (from 7.7 to 228 µmol/L for pyruvate and from 22.6 to 650 µM for total ketone bodies), accuracy (10.4 µmol/L in physiological range for pyruvate and 7.1 µmol/L for 3-hydroxybutyrate) and comparing methods (versus manual assay with spectrophotometry on Uvikon XL). Establishment of reference ranges (35 to 74 µmol/L for pyruvate, less than 100 µM for 3-hydroxybutyrate and less than 44 µmol/L for acetoacetate) and reagents stability study (up to 12 weeks if frozen) have enabled us to finalize method validation and to add these assays to our routine laboratory repertoire.