Advanced glycation endproducts, dityrosine and arginine transporter dysfunction in autism - a source of biomarkers for clinical diagnosis

Abstract

BackgroundClinical chemistry tests for autism spectrum disorder (ASD) are currently unavailable. The aim of this study was to explore the diagnostic utility of proteotoxic biomarkers in plasma and urine, plasma protein glycation, oxidation, and nitration adducts, and related glycated, oxidized, and nitrated amino acids (free adducts), for the clinical diagnosis of ASD.MethodsThirty-eight children with ASD (29 male, 9 female; age 7.6 ± 2.0 years) and 31 age-matched healthy controls (23 males, 8 females; 8.6 ± 2.0 years) were recruited for this study. Plasma protein glycation, oxidation, and nitration adducts and amino acid metabolome in plasma and urine were determined by stable isotopic dilution analysis liquid chromatography-tandem mass spectrometry. Machine learning methods were then employed to explore and optimize combinations of analyte data for ASD diagnosis.ResultsWe found that children with ASD had increased advanced glycation endproducts (AGEs), Nε-carboxymethyl-lysine (CML) and Nω-carboxymethylarginine (CMA), and increased oxidation damage marker, dityrosine (DT), in plasma protein, with respect to healthy controls. We also found that children with ASD had increased CMA free adduct in plasma ultrafiltrate and increased urinary excretion of oxidation free adducts, alpha-aminoadipic semialdehyde and glutamic semialdehyde. From study of renal handling of amino acids, we found that children with ASD had decreased renal clearance of arginine and CMA with respect to healthy controls. Algorithms to discriminate between ASD and healthy controls gave strong diagnostic performance with features: plasma protein AGEs—CML, CMA—and 3-deoxyglucosone-derived hydroimidazolone, and oxidative damage marker, DT. The sensitivity, specificity, and receiver operating characteristic area-under-the-curve were 92%, 84%, and 0.94, respectively.ConclusionsChanges in plasma AGEs were likely indicative of dysfunctional metabolism of dicarbonyl metabolite precursors of AGEs, glyoxal and 3-deoxyglucosone. DT is formed enzymatically by dual oxidase (DUOX); selective increase of DT as an oxidative damage marker implicates increased DUOX activity in ASD possibly linked to impaired gut mucosal immunity. Decreased renal clearance of arginine and CMA in ASD is indicative of increased arginine transporter activity which may be a surrogate marker of disturbance of neuronal availability of amino acids. Data driven combination of these biomarkers perturbed by proteotoxic stress, plasma protein AGEs and DT, gave diagnostic algorithms of high sensitivity and specificity for ASD.Electronic supplementary materialThe online version of this article (10.1186/s13229-017-0183-3) contains supplementary material, which is available to authorized users.

Multivariate Analysis of Plasma Metabolites in Children with Autism Spectrum Disorder and Gastrointestinal Symptoms Before and After Microbiota Transfer Therapy

“…There have been many other studies of metabolites in plasma or serum of children with ASD [37][38][39][40][41][42][43][44][45][46]. Several of these studies attempted to classify ASD versus TD children, with some of the most successful studies including Anwar et al [37] (four-metabolite model with sensitivity/specificity of 92%/84%) and Momeni et al [40] (three-peptide model with sensitivity/specificity of 95%/85%). Among these studies, none of them included cross-validation or validation in another study, unlike the aforementioned studies analyzing FOCM/TS metabolites [30,36].…”

Autism Spectrum Disorders — in Search of Mechanistic Biomarkers

“…It our own research we took an innovative approach of assessing the diagnostic utility of spontaneous low level glycation, oxidation and nitration modifications of proteins and related amino acid metabolites for diagno-sis of ASD [2]. Such biomarkers often shown subtle changes in multiple analytes or a "fingerprint" of metabolic disturbances in clinical conditions [14].…”

“…В наших собственных исследованиях мы использовали инновационный подход оценки диагностической полезности спонтанного низкого уровня гликирования, окисления и нитрации белков и связанных с ними аминокислотных метаболитов для диагностики РАС [2]. Такие биомаркеры часто демонстрируют незначительные изменения в нескольких определяемых элементах или «отпечаток» метаболических нарушений в клинических условиях [14].…”

Improving the diagnosis of autism spectrum disorder

“…In another strand of research, scientists have been being making the first steps towards what could potentially become a blood and urine test for autism, based on the finding that children with ASD have increased advanced glycation end products (AGEs) and increased amounts of the oxidative damage marker, dityrosine, in plasma protein compared with healthy controls. 5 However, any such biochemical test to 'detect' ASD is fraught with complication and a long way off and, for now, diagnosis still centres largely around the objective opinion of an expert in the field, supported by standardised tests. Even with the best will in the world, this is a route that can rarely be hurried.…”