Expression and oxidative modifications of plasma proteins in autism spectrum disorders: Interplay between inflammatory response and lipid peroxidation

Metabolomic analysis of plasma biomarkers in children with autism spectrum disorders

Autism spectrum disorder (ASD) presents a significant risk to human well-being and has emerged as a worldwide public health concern. Twenty-eight children with ASD and 33 healthy children (HC) were selected for the quantitative determination of their plasma metabolites using an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) platform. A total of 1997 metabolites were detected in the study cohort, from which 116 metabolites were found to be differentially expressed between the ASD and HC groups. Through analytical algorithms such as least absolute shrinkage selection operator (LASSO), support vector machine (SVM), and random forest (RF), three potential metabolic markers were identified as FAHFA (18:1(9Z)/9-O-18:0), DL-2-hydroxystearic acid, and 7(S),17(S)-dihydroxy-8(E),10(Z),13(Z),15(E),19(Z)-docosapentaenoic acid. These metabolites demonstrated superior performance in distinguishing the ASD group from the HC group, as indicated by the area under curves (AUCs) of 0.935, 0.897, and 0.963 for the three candidate biomarkers, respectively. The samples were divided into training and validation sets according to 7:3. Diagnostic models were constructed using logistic regression (LR), SVM, and RF. The constructed three-biomarker diagnostic model also exhibited strong discriminatory efficacy. These findings contribute to advancing our understanding of the underlying mechanisms involved in the occurrence of ASD and provide a valuable reference for clinical diagnosis.

Autism spectrum disorder: pathogenesis, biomarker, and intervention therapy

Autism spectrum disorder (ASD) has become a common neurodevelopmental disorder. The heterogeneity of ASD poses great challenges for its research and clinical translation. On the basis of reviewing the heterogeneity of ASD, this review systematically summarized the current status and progress of pathogenesis, diagnostic markers, and interventions for ASD. We provided an overview of the ASD molecular mechanisms identified by multi-omics studies and convergent mechanism in different genetic backgrounds. The comorbidities, mechanisms associated with important physiological and metabolic abnormalities (i.e., inflammation, immunity, oxidative stress, and mitochondrial dysfunction), and gut microbial disorder in ASD were reviewed. The non-targeted omics and targeting studies of diagnostic markers for ASD were also reviewed. Moreover, we summarized the progress and methods of behavioral and educational interventions, intervention methods related to technological devices, and research on medical interventions and potential drug targets. This review highlighted the application of high-throughput omics methods in ASD research and emphasized the importance of seeking homogeneity from heterogeneity and exploring the convergence of disease mechanisms, biomarkers, and intervention approaches, and proposes that taking into account individuality and commonality may be the key to achieve accurate diagnosis and treatment of ASD.

Mutations associated with autism lead to similar synaptic and behavioral alterations in both sexes of male and female mouse brain

Autism spectrum disorder (ASD) is a neurodevelopmental disorder based on synaptic abnormalities. The estimated prevalence rate of male individuals diagnosed with ASD prevails over females is in a proportion of 4:1. Consequently, males remain the main focus in ASD studies in clinical and experimental settings. Meanwhile, some studies point to an underestimation of this disorder in females. In this work, we studied the sex differences of the synaptic and behavioral phenotypes of ASD mouse models. Juvenile male and female Shank3Δ4-22 and Cntnap2-/- mutant mice and their WT littermates were used in the experiments. The animals were subjected to a Three-Chamber Sociability Test, then euthanized, and the whole cortex was used for the evaluation of the synaptic phenotype. Protein levels of glutamatergic (NR1) and GABAergic (GAD1 and VGAT) neuronal markers were measured. Protein level of synaptophysin (Syp) was also measured. Dendritic spine density in somatosensory neurons was analyzed by Golgi staining methods. Spine Density and GAD1, NR1, VGAT, and Syp levels were significantly reduced in Shank3Δ4-22 and Cntnap2-/- mice compared to the control group irrespective of sex, indicating impaired synaptic development in the mutant mice. These results were consistent with the lack of differences in the three-chamber sociability test between male and female mice. In conclusion, female ASD mice of both mutations undergo similar synaptic aberrations as their male counterparts and need to be studied along with the male animals. Finally, this work urges the psychiatry scientific community to use both sexes in their investigations.

Lipid Peroxidation via Regulating the Metabolism of Docosahexaenoic Acid and Arachidonic Acid in Autistic Behavioral Symptoms

The association between the lipid peroxidation product malondialdehyde (MDA)-modified low-density lipoprotein (MDA-LDL) and the pathophysiology of autism spectrum disorder (ASD) is unclear. This association was studied in 17 children with ASD and seven age-matched controls regarding autistic behaviors. Behavioral symptoms were assessed using the Aberrant Behavior Checklist (ABC). To compensate for the small sample size, adaptive Lasso was used to increase the likelihood of accurate prediction, and a coefficient of variation was calculated for suitable variable selection. Plasma MDA-LDL levels were significantly increased, and plasma SOD levels were significantly decreased in addition to significantly increased plasma docosahexaenoic acid (DHA) levels and significantly decreased plasma arachidonic acid (ARA) levels in the 17 subjects with ASD as compared with those of the seven healthy controls. The total ABC scores were significantly higher in the ASD group than in the control group. The results of multiple linear regression and adaptive Lasso analyses revealed an association between increased plasma DHA levels and decreased plasma ARA levels, which were significantly associated with total ABC score and increased plasma MDA-LDL levels. Therefore, an imbalance between plasma DHA and ARA levels induces ferroptosis via lipid peroxidation. Decreased levels of α-linolenic acid and γ-linolenic acid may be connected to the total ABC scores with regard to lipid peroxidation.

The use of data independent acquisition based proteomic analysis and machine learning to reveal potential biomarkers for autism spectrum disorder

Autism spectrum disorder (ASD) is a complex neurological developmental disorder in children, and is associated with social isolation and restricted interests. The etiology of this disorder is still unknown. There is neither any confirmed laboratory test nor any effective therapeutic strategy to diagnose or cure it. We performed data independent acquisition (DIA) and multiple reaction monitoring (MRM) analysis of plasma from children with ASD and controls. The result showed that 45 differentially expressed proteins (DEPs) were identified between autistic subjects and controls. Among these, only one DEP was down-regulated in ASD; other DEPs were up-regulated in ASD children's plasma. These proteins are found associated with complement and coagulation cascades, vitamin digestion and absorption, cholesterol metabolism, platelet degranulation, selenium micronutrient network, extracellular matrix organization and inflammatory pathway, which have been reported to be related to ASD. After MRM verification, five key proteins in complement pathway (PLG, SERPINC1, and A2M) and inflammatory pathway (CD5L, ATRN, SERPINC1, and A2M) were confirmed to be significantly up-regulated in ASD group. Through the screening of machine learning model and MRM verification, we found that two proteins (biotinidase and carbonic anhydrase 1) can be used as early diagnostic markers of ASD (AUC = 0.8, p = 0.0001). SIGNIFICANCE: ASD is the fastest growing neurodevelopmental disorder in the world and has become a major public health problem worldwide. Its prevalence has been steadily increasing, with a global prevalence rate of 1%. Early diagnosis and intervention can achieve better prognosis. In this study, data independent acquisition (DIA) and multiple reaction monitoring (MRM) analysis was applied to analyze the plasma proteome of ASD patients (31 (±5) months old), and 378 proteins were quantified. 45 differentially expressed proteins (DEPs) were identified between the ASD group and the control group. They mainly were associated with platelet degranulation, ECM proteoglycar, complement and coagulation cascades, selenium micronutrient network, regulation of insulin-like growth factor (IGF) transport and uptake by insulin-like growth factor binding proteins (IGFBPs), cholesterol metabolism, vitamin metabolism, and inflammatory pathway. Through the integrated machine learning methods and the MRM verification of independent samples, it is considered that biotinidase and carbon anhydrase 1 have the potential to become biomarkers for the early diagnosis of ASD. These results complement proteomics database of the ASD patients, broaden our understanding of ASD, and provide a panel of biomarkers for the early diagnosis of ASD.

Potential protein markers in children with Autistic Spectrum Disorder (ASD) revealed by salivary proteomics

The lack of specific pharmacological therapy for Autistic Spectrum Disorder (ASD) and its clinical heterogeneity demand efforts directed toward the identification of biomarkers to aid in diagnosis. Proteomics offers a new perspective for studying the altered proteins associated with autism spectrum disorders (ASD) and we have saliva as an easy-to-collect biological fluid with important biomolecules for investigating biomarkers in various diseases. In this sense, saliva could be used to identify potential biomarkers of ASD. In the current work, saliva samples were collected from children with different degrees of ASD and healthy children and proteomics approaches were applied to generate data on differentially expressed proteins between groups which will serve as a basis for future validation studies as protein markers. Data are available via ProteomeXchange with identifier PXD030065. As results, 132 proteins were present in 80% of the saliva pools of all analyzed groups. Twenty-five proteins were identified as overexpressed in the group of severe and mild/moderate ASD carriers, among which, eight were identified as potential biomarkers for ASD.

Oxidative Stress in Autism Spectrum Disorder-Current Progress of Mechanisms and Biomarkers

Autism spectrum disorder (ASD) is a type of neurodevelopmental disorder that has been diagnosed in an increasing number of children around the world. Existing data suggest that early diagnosis and intervention can improve ASD outcomes. However, the causes of ASD remain complex and unclear, and there are currently no clinical biomarkers for autism spectrum disorder. More mechanisms and biomarkers of autism have been found with the development of advanced technology such as mass spectrometry. Many recent studies have found a link between ASD and elevated oxidative stress, which may play a role in its development. ASD is caused by oxidative stress in several ways, including protein post-translational changes (e.g., carbonylation), abnormal metabolism (e.g., lipid peroxidation), and toxic buildup [e.g., reactive oxygen species (ROS)]. To detect elevated oxidative stress in ASD, various biomarkers have been developed and employed. This article summarizes recent studies about the mechanisms and biomarkers of oxidative stress. Potential biomarkers identified in this study could be used for early diagnosis and evaluation of ASD intervention, as well as to inform and target ASD pharmacological or nutritional treatment interventions.

The Metallome as a Link Between the "Omes" in Autism Spectrum Disorders

Metal dyshomeostasis plays a significant role in various neurological diseases such as Alzheimer's disease, Parkinson's disease, Autism Spectrum Disorders (ASD), and many more. Like studies investigating the proteome, transcriptome, epigenome, microbiome, etc., for years, metallomics studies have focused on data from their domain, i.e., trace metal composition, only. Still, few have considered the links between other "omes," which may together result in an individual's specific pathologies. In particular, ASD have been reported to have multitudes of possible causal effects. Metallomics data focusing on metal deficiencies and dyshomeostasis can be linked to functions of metalloenzymes, metal transporters, and transcription factors, thus affecting the proteome and transcriptome. Furthermore, recent studies in ASD have emphasized the gut-brain axis, with alterations in the microbiome being linked to changes in the metabolome and inflammatory processes. However, the microbiome and other "omes" are heavily influenced by the metallome. Thus, here, we will summarize the known implications of a changed metallome for other "omes" in the body in the context of "omics" studies in ASD. We will highlight possible connections and propose a model that may explain the so far independently reported pathologies in ASD.

A proteomic analysis of urine biomarkers in autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by early-onset social-communication challenges, restricted and repetitive behaviors, or unusual sensory-motor behaviors. A lack of specific biomarkers hinders the early diagnosis and treatment of this disease in many children. This study analyzes and validates potential urinary biomarkers using mass spectrometry proteomics. Global proteomics profiles of urine from 19 ASD patients and 19 healthy control subjects were compared to identify significantly changed proteins. These proteins were validated with targeted proteomics using parallel reaction monitoring (PRM) in an independent validation set consisting of samples from 40 ASD patients and 38 healthy controls. A total of 34 significantly changed proteins were found in the discovery set, among which seven proteins were identified as potential biomarkers for ASD through PRM assays in the validation set. Of these seven proteins, immunoglobulin kappa variable 4-1, immunoglobulin kappa variable 3-20, and immunoglobulin lambda variable 1-51 were up-regulated, while ATP synthase F1 subunit alpha, 10 kDa heat shock protein, apolipoprotein C-III, and arylsulfatase F were down-regulated. Six of these seven proteins support previous findings that ASD is accompanied by altered immune response and lipid metabolism, as well as mitochondrial dysfunction. This study lays the groundwork for additional research using biomarkers to clinically diagnose ASD. The proteomics and PRM raw data of this study have been deposited under the accession number IPX0002592000 at iProX. SIGNIFICANCE: This study identified 34 proteins in urine of ASD patients that were significantly changed from the urinary proteins of healthy subjects using LC-MS/MS-based proteomics in a discovery set. Seven of these proteins were validated by PRM analysis in an independent validation set. This report represents the first description of combined label-free quantitative proteomics and PRM analysis of targeted proteins for discovery of ASD urinary biomarkers. The results will be helpful for early diagnosis and can provide additional insight into the molecular mechanisms of ASD.

Oxidative Stress in Adults with Autism Spectrum Disorder: A Case Control Study

Oxidative stress has been proposed as being important in the pathophysiology of autism spectrum disorders (ASD), and heightened levels of oxidative stress has found in children with ASD. Our aim was to investigate, whether this change is temporary or persist into adulthood. We included 89 adult patients with ASD and sex and age matched controls. Plasma levels of antioxidants superoxide dismutase 1 (SOD1) and superoxide dismutase 2 (SOD2) and pro-oxidant xanthine oxidase (XO) were measured. Individuals with ASD had higher levels of SOD1, which furthermore correlated with autism severity as measured by autism quotient-score. We found no difference regarding SOD2 and XO between ASD group and controls. However, SOD1 and SOD2 were elevated in males compared to females.

The Role of Lipidomics in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a complex neurodevelopmental syndrome commonly diagnosed in early childhood; it is usually characterized by impairment in reciprocal communication and speech, repetitive behaviors, and social withdrawal with loss in communication skills. Its development may be affected by a variety of environmental and genetic factors. Trained physicians diagnose and evaluate the severity of ASD based on clinical evaluations of observed behaviors. As such, this approach is inevitably dependent on the expertise and subjective assessment of those administering the clinical evaluations. There is a need to identify objective biological markers associated with diagnosis or clinical severity of the disorder. Several important issues and concerns exist regarding the diagnostic competence of the many abnormal plasma metabolites produced in the different biochemical pathways evaluated in individuals with ASD. The search for high-performing bio-analytes to diagnose and follow-up ASD development is still a major target in medicine. Dysregulation in the oxidative stress response and proinflammatory processes are major etiological causes of ASD pathogenesis. Furthermore, dicarboxylic acid metabolites, cholesterol-related metabolites, phospholipid-related metabolites, and lipid transporters and mediators are impaired in different pathological conditions that have a role in the ASD etiology. A mechanism may exist by which pro-oxidant environmental stressors and abnormal metabolites regulate clinical manifestations and development of ASD.

The impact of glutathione metabolism in autism spectrum disorder

This paper reviews the potential role of glutathione (GSH) in autism spectrum disorder (ASD). GSH plays a key role in the detoxification of xenobiotics and maintenance of balance in intracellular redox pathways. Recent data showed that imbalances in the GSH redox system are an important factor in the pathophysiology of ASD. Furthermore, ASD is accompanied by decreased concentrations of reduced GSH in part caused by oxidation of GSH into glutathione disulfide (GSSG). GSSG can react with protein sulfhydryl (SH) groups, thereby causing proteotoxic stress and other abnormalities in SH-containing enzymes in the brain and blood. Moreover, alterations in the GSH metabolism via its effects on redox-independent mechanisms are other processes associated with the pathophysiology of ASD. GSH-related regulation of glutamate receptors such as the N-methyl-D-aspartate receptor can contribute to glutamate excitotoxicity. Synergistic and antagonistic interactions between glutamate and GSH can result in neuronal dysfunction. These interactions can involve transcription factors of the immune pathway, such as activator protein 1 and nuclear factor (NF)-κB, thereby interacting with neuroinflammatory mechanisms, ultimately leading to neuronal damage. Neuronal apoptosis and mitochondrial dysfunction are recently outlined as significant factors linking GSH impairments with the pathophysiology of ASD. Moreover, GSH regulates the methylation of DNA and modulates epigenetics. Existing data support a protective role of the GSH system in ASD development. Future research should focus on the effects of GSH redox signaling in ASD and should explore new therapeutic approaches by targeting the GSH system.

The role of glutathione redox imbalance in autism spectrum disorder: A review

The role of glutathione in autism spectrum disorder (ASD) is emerging as a major topic, due to its role in the maintenance of the intracellular redox balance. Several studies have implicated glutathione redox imbalance as a leading factor in ASD, and both ASD and many other neurodevelopmental disorders involve low levels of reduced glutathione (GSH), high levels of oxidized glutathione (GSSG), and abnormalities in the expressions of glutathione-related enzymes in the blood or brain. Glutathione metabolism, through its impact on redox environment or redox-independent mechanisms, interferes with multiple mechanisms involved in ASD pathogenesis. Glutathione-mediated regulation of glutamate receptors [e.g., N-methyl-d-aspartate (NMDA) receptor], as well as the role of glutamate as a substrate for glutathione synthesis, may be involved in the regulation of glutamate excitotoxicity. However, the interaction between glutathione and glutamate in the pathogenesis of brain diseases may vary from synergism to antagonism. Modulation of glutathione is also associated with regulation of redox-sensitive transcription factors nuclear factor kappa B (NF-κB) and activator protein 1 (AP-1) and downstream signaling (proinflammatory cytokines and inducible enzymes), thus providing a significant impact on neuroinflammation. Mitochondrial dysfunction, as well as neuronal apoptosis, may also provide a significant link between glutathione metabolism and ASD. Furthermore, it has been recently highlighted that glutathione can affect and modulate DNA methylation and epigenetics. Review analysis including research studies meeting the required criteria for analysis showed statistically significant differences between the plasma GSH and GSSG levels as well as GSH:GSSG ratio in autistic patients compared with healthy individuals (P = 0.0145, P = 0.0150 and P = 0.0202, respectively). Therefore, the existing data provide a strong background on the role of the glutathione system in ASD pathogenesis. Future research is necessary to investigate the role of glutathione redox signaling in ASD, which could potentially also lead to promising therapeutics.

Air Pollution-Related Brain Metal Dyshomeostasis as a Potential Risk Factor for Neurodevelopmental Disorders and Neurodegenerative Diseases

Increasing evidence links air pollution (AP) exposure to effects on the central nervous system structure and function. Particulate matter AP, especially the ultrafine (nanoparticle) components, can carry numerous metal and trace element contaminants that can reach the brain in utero and after birth. Excess brain exposure to either essential or non-essential elements can result in brain dyshomeostasis, which has been implicated in both neurodevelopmental disorders (NDDs; autism spectrum disorder, schizophrenia, and attention deficit hyperactivity disorder) and neurodegenerative diseases (NDGDs; Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and amyotrophic lateral sclerosis). This review summarizes the current understanding of the extent to which the inhalational or intranasal instillation of metals reproduces in vivo the shared features of NDDs and NDGDs, including enlarged lateral ventricles, alterations in myelination, glutamatergic dysfunction, neuronal cell death, inflammation, microglial activation, oxidative stress, mitochondrial dysfunction, altered social behaviors, cognitive dysfunction, and impulsivity. Although evidence is limited to date, neuronal cell death, oxidative stress, and mitochondrial dysfunction are reproduced by numerous metals. Understanding the specific contribution of metals/trace elements to this neurotoxicity can guide the development of more realistic animal exposure models of human AP exposure and consequently lead to a more meaningful approach to mechanistic studies, potential intervention strategies, and regulatory requirements.

Proteomics and Metabolomics Approaches towards a Functional Insight onto AUTISM Spectrum Disorders: Phenotype Stratification and Biomarker Discovery

Autism spectrum disorders (ASDs) are neurodevelopmental disorders characterized by behavioral alterations and currently affect about 1% of children. Significant genetic factors and mechanisms underline the causation of ASD. Indeed, many affected individuals are diagnosed with chromosomal abnormalities, submicroscopic deletions or duplications, single-gene disorders or variants. However, a range of metabolic abnormalities has been highlighted in many patients, by identifying biofluid metabolome and proteome profiles potentially usable as ASD biomarkers. Indeed, next-generation sequencing and other omics platforms, including proteomics and metabolomics, have uncovered early age disease biomarkers which may lead to novel diagnostic tools and treatment targets that may vary from patient to patient depending on the specific genomic and other omics findings. The progressive identification of new proteins and metabolites acting as biomarker candidates, combined with patient genetic and clinical data and environmental factors, including microbiota, would bring us towards advanced clinical decision support systems (CDSSs) assisted by machine learning models for advanced ASD-personalized medicine. Herein, we will discuss novel computational solutions to evaluate new proteome and metabolome ASD biomarker candidates, in terms of their recurrence in the reviewed literature and laboratory medicine feasibility. Moreover, the way to exploit CDSS, performed by artificial intelligence, is presented as an effective tool to integrate omics data to electronic health/medical records (EHR/EMR), hopefully acting as added value in the near future for the clinical management of ASD.

How 25(OH)D Levels during Pregnancy Affect Prevalence of Autism in Children: Systematic Review

Autism spectrum disorder (ASD) is a group of dysfunctions in social interaction, communication, and behaviors. The etiology of ASD is not yet fully understood; however, it consists of the interaction between genetics and the environment. An increasing amount of evidence points to the possibility that gestational and early-childhood vitamin D deficiency may be involved in the etiology of some cases of ASD. Herein, we systematically review the literature for studies on vitamin D status during pregnancy and ASD outcomes. Forty-three studies in the PubMed and 124 studies in EMBASE databases were initially found. After screening, 26 were identified as candidate studies for inclusion. Finally, 14 articles met the inclusion criteria, which originated from nine countries. The studies included 10 original research studies and four review studies conducted between 2012 and 2020. The strength of evidence that vitamin D levels during pregnancy increase the risk of developing autism is very low. This is because the evidence relies exclusively on observational studies that did not equally consider all important confounders and that assessed the indirect relationship between vitamin D as a surrogate for sunlight exposure and autism risk. The findings of this systematic review are consistent with the hypothesis that low vitamin D levels might contribute to the development of autism. However, we must also recognize the possible confusion bias and therefore experimental studies with very large sample sizes, given incidence of autism, that allow us to detect blood levels in pregnant women would be helpful to clarify this point.

Whole-Exome Sequencing Identifies Three Candidate Homozygous Variants in a Consanguineous Iranian Family with Autism Spectrum Disorder and Skeletal Problems

Autism spectrum disorder (ASD) is characterized by 3 core symptoms with impaired social communication, repetitive behavior, and/or restricted interests in early childhood. As a complex neurodevelopmental disorder (NDD), the phenotype and severity of autism are extremely heterogeneous. Genetic factors have a key role in the etiology of autism. In this study, we investigated an Azeri Turkish family with 2 ASD-affected individuals to identify probable ASD-causing variants. First, the affected individuals were karyotyped in order to exclude chromosomal abnormalities. Then, whole-exome sequencing was carried out in one affected sibling followed by cosegregation analysis for the candidate variants in the family. In addition, SNP genotyping was carried out in the patients to identify possible homozygosity regions. Both proband and sibling had a normal karyotype. We detected 3 possible causative variants in this family: c.5443G>A; p.Gly1815Ser, c.1027C>T; p.Arg343Trp, and c.382A>G; p.Lys128Glu, which are in the FBN1, TF, and PLOD2 genes, respectively. All of the variants cosegregated in the family, and SNP genotyping revealed that these 3 variants are located in the homozygosity regions. This family serves as an example of a multimodal polygenic risk for a complex developmental disorder. Of these 3 genes, confluence of the variants in FBN1 and PLOD2 may contribute to the autistic features of the patient in addition to skeletal problems. Our study highlights the genetic complexity and heterogeneity of NDDs such as autism. In other words, in some patients with ASD, multiple rare variants in different loci rather than a monogenic state may contribute to the development of phenotypes.

Yin-Yang Mechanisms Regulating Lipid Peroxidation of Docosahexaenoic Acid and Arachidonic Acid in the Central Nervous System

Phospholipids in the central nervous system (CNS) are rich in polyunsaturated fatty acids (PUFAs), particularly arachidonic acid (ARA) and docosahexaenoic acid (DHA). Besides providing physical properties to cell membranes, these PUFAs are metabolically active and undergo turnover through the “deacylation-reacylation (Land's) cycle”. Recent studies suggest a Yin-Yang mechanism for metabolism of ARA and DHA, largely due to different phospholipases A₂ (PLA₂s) mediating their release. ARA and DHA are substrates of cyclooxygenases and lipoxygenases resulting in an array of lipid mediators, which are pro-inflammatory and pro-resolving. The PUFAs are susceptible to peroxidation by oxygen free radicals, resulting in the production of 4-hydroxynonenal (4-HNE) from ARA and 4-hydroxyhexenal (4-HHE) from DHA. These alkenal electrophiles are reactive and capable of forming adducts with proteins, phospholipids and nucleic acids. The perceived cytotoxic and hormetic effects of these hydroxyl-alkenals have impacted cell signaling pathways, glucose metabolism and mitochondrial functions in chronic and inflammatory diseases. Due to the high levels of DHA and ARA in brain phospholipids, this review is aimed at providing information on the Yin-Yang mechanisms for regulating these PUFAs and their lipid peroxidation products in the CNS, and implications of their roles in neurological disorders.

The concomitant lower concentrations of vitamins B6, B9 and B12 may cause methylation deficiency in autistic children

Autism spectrum disorder (ASD) is characterized by severe and persistent difficulties in social communication and social interaction at multiple levels. Recently, metabolic disorders have been associated with most cases of patients with ASD. The aim of this study was to investigate, through a new and more sophisticated mass technique, such as UHPLC-mass spectrometry (Q-exactive analyzer), alteration in metabolisms analyzing ASD children urine samples from children showing simultaneous vitamin B6, B9 and B12 deficiencies. This in order to study how these concurrent deficiencies may influence some phenotypic aspects of autistic disorder. Thus, urinary metabolic patterns specific to ASD were explored at an early age in 60 children with ASD, showing lower three vitamins levels, and 60 corresponding controls (age group 3-8, M: F=42:18). The results showed significant block of cystathionine formation with consequent accumulation of homocysteine. A lower glutathione levels (GSH), with reduction of essential intracellular reducing environment required for normal immune function, detoxification capacity and redox-sensitive enzyme activity. Increased concentration of 5-methyltetrahydrofolate, which leads to a lower availability of methyl group and significant decrease in urinary methionine and S-adenosyl-L-methionine (SAM) concentrations, the major methyl donor. The latter justify the well-known reduction in protein and DNA methylation reported in autistic children. As a final consideration, the concomitant deficiencies of all three B vitamins, recorded in a significant number of autistic children, suggests that intestinal dysbiosis in these patients may be the main cause of a reduction in their absorption, in addition to the genetic mutation of a specific gene.

Phenotypic subgrouping and multi-omics analyses reveal reduced diazepam-binding inhibitor (DBI) protein levels in autism spectrum disorder with severe language impairment

BACKGROUND

The mechanisms underlying autism spectrum disorder (ASD) remain unclear, and clinical biomarkers are not yet available for ASD. Differences in dysregulated proteins in ASD have shown little reproducibility, which is partly due to ASD heterogeneity. Recent studies have demonstrated that subgrouping ASD cases based on clinical phenotypes is useful for identifying candidate genes that are dysregulated in ASD subgroups. However, this strategy has not been employed in proteome profiling analyses to identify ASD biomarker proteins for specific subgroups.

METHODS

We therefore conducted a cluster analysis of the Autism Diagnostic Interview-Revised (ADI-R) scores from 85 individuals with ASD to predict subgroups and subsequently identified dysregulated genes by reanalyzing the transcriptome profiles of individuals with ASD and unaffected individuals. Proteome profiling of lymphoblastoid cell lines from these individuals was performed via 2D-gel electrophoresis, and then mass spectrometry. Disrupted proteins were identified and compared to the dysregulated transcripts and reported dysregulated proteins from previous proteome studies. Biological functions were predicted using the Ingenuity Pathway Analysis (IPA) program. Selected proteins were also analyzed by Western blotting.

RESULTS

The cluster analysis of ADI-R data revealed four ASD subgroups, including ASD with severe language impairment, and transcriptome profiling identified dysregulated genes in each subgroup. Screening via proteome analysis revealed 82 altered proteins in the ASD subgroup with severe language impairment. Eighteen of these proteins were further identified by nano-LC-MS/MS. Among these proteins, fourteen were predicted by IPA to be associated with neurological functions and inflammation. Among these proteins, diazepam-binding inhibitor (DBI) protein was confirmed by Western blot analysis to be expressed at significantly decreased levels in the ASD subgroup with severe language impairment, and the DBI expression levels were correlated with the scores of several ADI-R items.

CONCLUSIONS

By subgrouping individuals with ASD based on clinical phenotypes, and then performing an integrated transcriptome-proteome analysis, we identified DBI as a novel candidate protein for ASD with severe language impairment. The mechanisms of this protein and its potential use as an ASD biomarker warrant further study.

Advances in Biomarker Studies in Autism Spectrum Disorders

Autism spectrum disorder (ASD) is a neurological and developmental condition that begins early in childhood and lasts throughout life. The epidemiology of ASD is continuously increasing all over the world with huge social and economical burdens. As the etiology of autism is not completely understood, there is still no medication available for the treatment of this disorder. However, some behavioral interventions are available to improve the core and associated symptoms of autism, particularly when initiated at an early stage. Thus, there is an increasing demand for finding biomarkers for ASD. Although diagnostic biomarkers have not yet been established, research efforts have been carried out in neuroimaging and biological analyses including genomics and gene testing, proteomics, metabolomics, transcriptomics, and studies of the immune system, inflammation, and microRNAs. Here, we will review the current progress in these fields and focus on new methods, developments, research strategies, and studies of blood-based biomarkers.

Vitamin D and autism, what's new?

An increasing amount of evidence points to the possibility that gestational and early childhood vitamin D deficiency [25(OH)D < 40 ng/ml] cause some cases of autism. Vitamin D is metabolized into a seco-steroid hormone that regulates about 3% of the 26,000 genes in the coding human genome. It is also a neurosteroid that is active in brain development, having effects on cellular proliferation, differentiation, calcium signaling, neurotrophic and neuroprotective actions; it also appears to have an effect on neurotransmission and synaptic plasticity. Children who are, or who are destined to become, autistic have lower 25(OH)D levels at 3 months of gestation, at birth and at age 8 compared to their unaffected siblings. Two open label trials found high dose vitamin D improves the core symptoms of autism in about 75% of autistic children. A few of the improvements were remarkable. The vitamin D doses used in these children were 300 IU/KG/day up to a maximum of 5000 IU/day (highest final 25(OH)D level reached was 45 ng/ml). The other study used 150,000 IU/month IM as well as 400 IU/day [highest final 25(OH)D level was 52 ng/ml]. These two open label trials were recently confirmed with a randomized controlled trial (RCT) using 300 IU/kg/day with a maximum of 5000 IU/day and resulted in effects similar to the two open label studies. In terms of prevention, a recent small study showed vitamin D supplementation during pregnancy (5000 IU/day) and during infancy and early childhood (1000 IU/day) significantly reduced the expected incidence of autism in mothers who already had one autistic child from 20% to 5%. Vitamin D is safe; for example, over the last 15 years, Poison Control reports there have been approximately 15,000 cases of vitamin D overdose. However only three of these 15,000 people developed clinical toxicity and no one died. Given those facts, practitioners might consider treating autism with 300 IU/kg/day, and seek to prevent autism by supplementing pregnant and lactating women (5000 IU/day) and infants and young children (150 IU/kg/day) checking 25(OH)D levels every 3 months. These doses will increase 25(OH)D blood levels to those recommended by the Endocrine Society. As the American Academy of Pediatrics recommends vitamin D supplementation during infancy and childhood, pediatricians and family practitioners should evaluate the current evidence on autism and vitamin D and act accordingly.

Toll-like receptor 4 signaling is associated with upregulated NADPH oxidase expression in peripheral T cells of children with autism

Autism spectrum disorders (ASD) affect millions of children worldwide, and are characterized by impairment in social interaction and communication, and specific repetitive behavioral patterns. Growing evidence highlights a role of toll-like receptors (TLRs) in the pathogenesis of ASD. Specifically, TLR-4 activation has been shown to be associated with increased pro-inflammatory cytokines as well as autistic symptoms in offspring. NADPH oxidase (NOX-2) derived reactive oxygen species (ROS) have also been shown to play pathogenic role under inflammatory conditions. However, the role of TLR-4 in the regulation of NOX-2 derived ROS has not been explored in ASD, particularly in T cells. Therefore, this study explored TLR-4 and NOX-2 related signaling in peripheral T cells of ASD patients (n=35) and age-matched typically developing children (n=30). In this study, we find that ASD individuals have increased TLR-4 expression on T cells which is associated with increased NOX-2 expression and ROS generation as compared to typically developing children. Moreover, activation of TLR-4 on T cells by lipopolysaccharide (LPS) in vitro leads to enhanced generation of NOX-2 derived ROS via nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) pathway. These data support a link between T cell TLR-4 activation and NOX-2/ROS upregulation in ASD patients. Our study has implications in the context of neuroinflammation observed in ASD patients as ROS may lead to amplification and perpetuation of inflammation both in the periphery and central nervous system. Our data also suggest that therapeutic targeting of TLR-4 signaling may lead to reduction in inflammation of ASD patients.

New evidences on the altered gut microbiota in autism spectrum disorders

BACKGROUND

Autism spectrum disorders (ASDs) are neurodevelopmental conditions characterized by social and behavioural impairments. In addition to neurological symptoms, ASD subjects frequently suffer from gastrointestinal abnormalities, thus implying a role of the gut microbiota in ASD gastrointestinal pathophysiology.

RESULTS

Here, we characterized the bacterial and fungal gut microbiota in a cohort of autistic individuals demonstrating the presence of an altered microbial community structure. A fraction of 90% of the autistic subjects were classified as severe ASDs. We found a significant increase in the Firmicutes/Bacteroidetes ratio in autistic subjects due to a reduction of the Bacteroidetes relative abundance. At the genus level, we observed a decrease in the relative abundance of Alistipes, Bilophila, Dialister, Parabacteroides, and Veillonella in the ASD cohort, while Collinsella, Corynebacterium, Dorea, and Lactobacillus were significantly increased. Constipation has been then associated with different bacterial patterns in autistic and neurotypical subjects, with constipated autistic individuals characterized by high levels of bacterial taxa belonging to Escherichia/Shigella and Clostridium cluster XVIII. We also observed that the relative abundance of the fungal genus Candida was more than double in the autistic than neurotypical subjects, yet due to a larger dispersion of values, this difference was only partially significant.

CONCLUSIONS

The finding that, besides the bacterial gut microbiota, also the gut mycobiota contributes to the alteration of the intestinal microbial community structure in ASDs opens the possibility for new potential intervention strategies aimed at the relief of gastrointestinal symptoms in ASDs.