Research Progress in Vitamin A and Autism Spectrum Disorder

Association of the retinol to all-trans retinoic acid pathway with autism spectrum disorder

BACKGROUND

Autism spectrum disorder (ASD) is a complex group of neurodevelopmental disorders. Research has highlighted a close association between the retinoic acid (RA) signaling pathway and ASD. This study investigates alterations in the vitamin A (VA, retinol) to RA metabolic pathway in children with ASD and speculates on the underlying reasons for these changes. We propose a subtype characterized by downregulated RA signaling in ASD, laying the groundwork for precise diagnosis and treatment research.

METHODS

We included 489 children with ASD and 280 typically developing (TD) children. Those with ASD underwent evaluations of core symptoms and neuro-developmental levels, which were conducted by professional developmental behavior physicians using assessment scales. Serum VA and all-trans RA (atRA) levels were determined by high-performance liquid chromatography and ultra-high-performance liquid chromatography-tandem mass spectrometry. The expression levels and concentrations of enzyme molecules such as retinol dehydrogenase 10 were assessed using quantitative polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

Children with ASD exhibited reduced serum atRA, accompanied by a downregulation of atRA synthesis enzymes. The reduction in serum atRA levels was linked not only to VA levels but also to the aberrant expression of metabolic enzymes responsible for atRA. Furthermore, the serum atRA levels in children with ASD were more strongly correlated with core symptoms and neurodevelopmental levels than VA levels.

CONCLUSION

Children with ASD exhibited a dual regulation of reduced serum atRA levels, influenced by both VA levels and abnormal expression of atRA metabolic enzymes.

Label free quantitative proteomic profiling of serum samples of intellectually disabled young patients revealed dysregulation of complement coagulation and cholesterol cascade systems

Intellectual disability is a heterogeneous disorder, diagnosed using intelligence quotient (IQ) score criteria. Currently, no specific clinical test is available to diagnose the disease and its subgroups due to inadequate understanding of the pathophysiology. Therefore, current study was designed to explore the molecular mechanisms involved in disease perturbation, and to identify potential biomarkers for disease diagnosis and prognosis. A total of 250 participants were enrolled in this study, including 200 intellectually disabled (ID) subjects from the subgroups (mild, moderate, and severe) with age and gender matched healthy controls (n = 50). Initially, IQ testing score and biochemical profile of each subject was generated, followed by label-free quantitative proteomics of subgroups of IQ and healthy control group through nano-LC/MS- mass spectrometry. A total of 310 proteins were identified, among them198 proteins were common among all groups. Statistical analysis (ANOVA) of the subgroups of ID showed 142 differentially expressed proteins, in comparison to healthy control group. From these, 120 proteins were found to be common among all subgroups. The remaining 22 proteins were categorized as exclusive proteins found only in disease subgroups. Furthermore, the hierarchical cluster analysis (HCL) of common significant proteins was also performed, followed by PANTHER protein classification and GO functional enrichment analysis. Results provides that the datasets of differentially expressed proteins, belong to the categories of immune / defense proteins, transfer carrier proteins, apolipoproteins, complement proteins, protease inhibitors, hemoglobin proteins etc., they are known to involvein immune system, and complement and coagulation pathway cascade and cholesterol metabolism pathway. Exclusively expressed 22 proteins were found to be disease stage specific and strong PPI network specifically those that have significant role in platelets activation and degranulation, such as Filamin A (FLNA). Furthermore, to validate the mass spectrometric findings, four highly significant proteins (APOA4, SAP, FLNA, and SERPING) were quantified by ELISA in all the study subjects. AUROC analysis showed a significant association of APOA4 (0.830), FLNA (0.958), SAP (0.754) and SERPING (0.600) with the disease. Apolipoprotein A4 (APOA4) has a significant role in cholesterol transport, and in modulation of glucose and lipid metabolism in the CNS. Similarly, FLNA has a crucial role in the nervous system, especially in the functioning of synaptic network. Therefore, both APOA4, and FLNA proteins represent good potential for candidate biomarkers for the diagnosis and prognosis of the intellectual disability. Overall, serum proteome of ID patients provides valuable information of proteins/pathways that are altered during ID progression.

Developmental exposure to pesticides that disrupt retinoic acid signaling causes persistent retinoid and behavioral dysfunction in zebrafish

Early developmental exposure to environmental toxicants may play a role in the risk for developing autism. A variety of pesticides have direct effects on retinoic acid (RA) signaling and as RA signaling has important roles in neurodevelopment, such compounds may cause developmental neurotoxicity through an overlapping adverse outcome pathway. It is hypothesized that a pesticide's embryonic effects on retinoid function may correspond with neurobehavioral disruption later in development. In the current studies, we determined the effects of RA-acting pesticides on neurobehavioral development in zebrafish. Buprofezin and imazalil caused generalized hypoactivity in the larval motility test, whereas chlorothalonil and endosulfan I led to selective hypoactivity and hyperactivity, respectively. With buprofezin, chlorothalonil, and imazalil, hypoactivity and/or novel anxiety-like behaviors persisted in adulthood and buprofezin additionally decreased social attraction responses in adulthood. Endosulfan I did not produce significant adult behavioral effects. Using qPCR analyses of adult brain tissue, we observed treatment-induced alterations in RA synthesis or catabolic genes, indicating persistent changes in RA homeostasis. These changes were compound-specific, with respect to expression directionality, and potential patterns of homeostatic disruption. Results suggest the likely persistence of disruptions in RA signaling well into adulthood and may represent compensatory mechanisms following early life stage exposures. This study demonstrates that early developmental exposure to environmental toxicants that interfere with RA signaling causes short as well as long-term behavioral disruption in a well-established zebrafish behavioral model and expand upon the meaning of the RA adverse outcome pathway, indicating that observed effects likely correspond with the nature of underlying homeostatic effects.

Tracing vitamins on the long non-coding lane of the transcriptome: vitamin regulation of LncRNAs

A major revelation of genome-scale biological studies in the post-genomic era has been that two-thirds of human genes do not encode proteins. The majority of non-coding RNA transcripts in humans are long non-coding RNA (lncRNA) molecules, non-protein-coding regulatory transcripts with sizes greater than 500 nucleotides. LncRNAs are involved in nearly every aspect of cellular physiology, playing fundamental regulatory roles both in normal cells and in disease. As result, they are functionally linked to multiple human diseases, from cancer to autoimmune, inflammatory, and neurological disorders. Numerous human conditions and diseases stem from gene-environment interactions; in this regard, a wealth of reports demonstrate that the intake of specific and essential nutrients, including vitamins, shapes our transcriptome, with corresponding impacts on health. Vitamins command a vast array of biological activities, acting as coenzymes, antioxidants, hormones, and regulating cellular proliferation and coagulation. Emerging evidence suggests that vitamins and lncRNAs are interconnected through several regulatory axes. This type of interaction is expected, since lncRNA has been implicated in sensing the environment in eukaryotes, conceptually similar to riboswitches and other RNAs that act as molecular sensors in prokaryotes. In this review, we summarize the peer-reviewed literature to date that has reported specific functional linkages between vitamins and lncRNAs, with an emphasis on mammalian models and humans, while providing a brief overview of the source, metabolism, and function of the vitamins most frequently investigated within the context of lncRNA molecular mechanisms, and discussing the published research findings that document specific connections between vitamins and lncRNAs.

An Open-Label Case Series of Glutathione Use for Symptomatic Management in Children with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a type of neurodevelopmental disorder that has been diagnosed in an increasing number of children around the world. The existing data suggest that early diagnosis and intervention can improve ASD outcomes. The causes of ASD remain complex and unclear, and there are currently no clinical biomarkers for autism spectrum disorder. There is an increasing recognition that ASD might be associated with oxidative stress through several mechanisms including abnormal metabolism (lipid peroxidation) and the toxic buildup of reactive oxygen species (ROS). Glutathione acts as an antioxidant, a free radical scavenger and a detoxifying agent. This open-label pilot study investigates the tolerability and effectiveness of oral supplementation with OpitacTM gluthathione as a treatment for patients with ASD. The various aspects of glutathione OpitacTM glutathione bioavailability were examined when administered by oral routes. The absorption of glutathione from the gastrointestinal tract has been recently investigated. The results of this case series suggest that oral glutathione supplementation may improve oxidative markers, but this does not necessarily translate to the observed clinical improvement of subjects with ASD. The study reports a good safety profile of glutathione use, with stomach upset reported in four out of six subjects. This article discusses the role of the gut microbiome and redox balance in ASD and notes that a high baseline oxidative burden may make some patients poor responders to glutathione supplementation. In conclusion, an imbalance in redox reactions is only one of the many factors contributing to ASD, and further studies are necessary to investigate other factors, such as impaired neurotransmission, immune dysregulation in the brain, and mitochondrial dysfunction.

A Multifaceted Presentation of Xerophthalmia in Autistic Patients

We report the manifestations of vitamin A deficiency (VAD) in three children with underlying autism of different stages. These children were under developmental paediatrician follow-up for autism, and the VAD was not detected until these children presented to Ophthalmology screening for varying stages of signs and symptoms. On further assessment, all of our patients have VAD secondary to poor dietary intake, as autistic patients are associated with having selective eating habits. In our case series, we discuss the spectrum of xerophthalmia presentations, which can be mild and can manifest as punctate epithelial erosions to the more blinding complications at the advanced stage of the disease, mainly irreversible optic neuropathy. The primary management is to address the dietary routine coupled with systemic administration of vitamin A.

Viruses and autism: A Bi-mutual cause and effect

Autism spectrum disorder (ASD) is a group of heterogeneous, multi-factorial, neurodevelopmental disorders resulting from genetic and environmental factors interplay. Infection is a significant trigger of autism, especially during the critical developmental period. There is a strong interplay between the viral infection as a trigger and a result of ASD. We aim to highlight the mutual relationship between autism and viruses. We performed a thorough literature review and included 158 research in this review. Most of the literature agreed on the possible effects of the viral infection during the critical period of development on the risk of developing autism, especially for specific viral infections such as Rubella, Cytomegalovirus, Herpes Simplex virus, Varicella Zoster Virus, Influenza virus, Zika virus, and severe acute respiratory syndrome coronavirus 2. Viral infection directly infects the brain, triggers immune activation, induces epigenetic changes, and raises the risks of having a child with autism. At the same time, there is some evidence of increased risk of infection, including viral infections in children with autism, due to lots of factors. There is an increased risk of developing autism with a specific viral infection during the early developmental period and an increased risk of viral infections in children with autism. In addition, children with autism are at increased risk of infection, including viruses. Every effort should be made to prevent maternal and early-life infections and reduce the risk of autism. Immune modulation of children with autism should be considered to reduce the risk of infection.

The association of vitamin A, zinc and copper levels with clinical symptoms in children with autism spectrum disorders in Jilin Province, China

BACKGROUND

This study evaluated vitamin A (VA), copper (Cu), and zinc (Zn) levels in the population with autism spectrum disorder (ASD) in Jilin Province, China. Furthermore, we examined their links to core symptoms and neurodevelopment, as well as gastrointestinal (GI) comorbidities and sleep disorders.

METHODS

This study included 181 children with autism and 205 typically developing (TD) children. The participants had not taken vitamin/mineral supplements in the prior three months. High-performance liquid chromatography was used to measure serum VA levels. By using inductively coupled plasma-mass spectrometry, Zn and Cu concentrations in plasma were determined. Importantly, the Childhood Autism Rating Scale, the Social Responsiveness Scale, and the Autism Behavior Checklist were used to measure core ASD symptoms. However, the Griffith Mental Development Scales-Chinese were used to measure neurodevelopment. GI comorbidities and sleep abnormalities were assessed with the 6 Item-Gastrointestinal Severity Index and Children's Sleep Habits Questionnaire, respectively. Children with ASD with GI issues were grouped according to severity (low GI severity and high GI severity groups).

RESULTS

(i) The difference in VA, Zn, Cu levels and the Zn/Cu ratio between ASD and TD children is small. But children with ASD had lower VA levels and Zn/Cu ratio, higher Cu levels than TD children. Cu levels in children with ASD were associated with the severity of core symptoms. (ii) Children with ASD were much more likely than their TD counterparts to suffer from GI comorbidities or sleep problems. Furthermore, it was observed that high GI severity was associated with lower levels of VA, whereas low GI severity was associated with higher levels of VA. (iii) The children with ASD who had both lower VA and lower Zn/Cu ratio had more severe scores on the Autism Behavior Checklist, but not on other measures.

CONCLUSION

Children with ASD had lower VA and Zn/Cu ratio, and higher Cu levels. Cu levels in children with ASD were weakly correlated with one subscale on social or self-help. ASD children with lower VA levels may face more serious GI comorbidities. Children with ASD combined VA-Zn/Cu lower had more severe core symptoms.

TRIAL REGISTRATION

Registration number: ChiCTR-OPC-17013502. Date of registration: 2017-11-23.

Narrative Review: The Effect of Vitamin A Deficiency on Gut Microbiota and Their Link with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders defined by a lack of social behaviors, repetitive behaviors and nonverbal interactions, such as limited eye contact, facial expression, and body gesturing. It is not a single condition, but rather a multi-factorial disorder caused by hereditary and non-genetic risk factors, as well as their interaction. According to several studies, the gut microbiota may have a role in the pathophysiology of autism spectrum disorder. Various studies have found differences in the composition of the gastrointestinal (GI) microbiota in children with ASD compared to unaffected siblings and/or healthy unrelated controls. The processes that relate the gut microbiota to brain dysfunctions (the gut-brain axis) in ASD are yet to be fully understood. However, the differences in the gastrointestinal composition might be due to vitamin A deficiency because vitamin A (VA) plays a role in the regulation of the intestinal microbiota. This narrative review discusses the impact of vitamin A deficiency on the gut microbiota composition and tries to understand how this may contribute for the development and severity of ASD.

Autism Spectrum Disorder: Neurodevelopmental Risk Factors, Biological Mechanism, and Precision Therapy

Autism spectrum disorder (ASD) is a heterogeneous, behaviorally defined neurodevelopmental disorder. Over the past two decades, the prevalence of autism spectrum disorders has progressively increased, however, no clear diagnostic markers and specifically targeted medications for autism have emerged. As a result, neurobehavioral abnormalities, neurobiological alterations in ASD, and the development of novel ASD pharmacological therapy necessitate multidisciplinary collaboration. In this review, we discuss the development of multiple animal models of ASD to contribute to the disease mechanisms of ASD, as well as new studies from multiple disciplines to assess the behavioral pathology of ASD. In addition, we summarize and highlight the mechanistic advances regarding gene transcription, RNA and non-coding RNA translation, abnormal synaptic signaling pathways, epigenetic post-translational modifications, brain-gut axis, immune inflammation and neural loop abnormalities in autism to provide a theoretical basis for the next step of precision therapy. Furthermore, we review existing autism therapy tactics and limits and present challenges and opportunities for translating multidisciplinary knowledge of ASD into clinical practice.

Involvement of retinoic acid receptor α in the autistic-like behavior of rats with vitamin A deficiency by regulating neurexin 1 in the visual cortex: a mechanism study

OBJECTIVES

To study the mechanism of retinoic acid receptor α (RARα) signal change to regulate neurexin 1 (NRXN1) in the visual cortex and participate in the autistic-like behavior in rats with vitamin A deficiency (VAD).

METHODS

The models of vitamin A normal (VAN) and VAD pregnant rats were established, and some VAD maternal and offspring rats were given vitamin A supplement (VAS) in the early postnatal period. Behavioral tests were performed on 20 offspring rats in each group at the age of 6 weeks. The three-chamber test and the open-field test were used to observe social behavior and repetitive stereotyped behavior. High-performance liquid chromatography was used to measure the serum level of retinol in the offspring rats in each group. Electrophysiological experiments were used to measure the long-term potentiation (LTP) level of the visual cortex in the offspring rats. Quantitative real-time PCR and Western blot were used to measure the expression levels of RARα, NRXN1, and N-methyl-D-aspartate receptor 1 (NMDAR1). Chromatin co-immunoprecipitation was used to measure the enrichment of RARα transcription factor in the promoter region of the NRXN1 gene.

RESULTS

The offspring rats in the VAD group had autistic-like behaviors such as impaired social interactions and repetitive stereotypical behaviors, and VAS started immediately after birth improved most of the behavioral deficits in offspring rats. The offspring rats in the VAD group had a significantly lower serum level of retinol than those in the VAN and VAS groups (P<0.05). Compared with the offspring rats in the VAN and VAS groups, the offspring rats in the VAD group had significant reductions in the mRNA and protein expression levels of NMDAR1, RARα, and NRXN1 and the LTP level of the visual cortex (P<0.05). The offspring rats in the VAD group had a significant reduction in the enrichment of RARα transcription factor in the promoter region of the NRXN1 gene in the visual cortex compared with those in the VAN and VAS groups (P<0.05).

CONCLUSIONS

RARα affects the synaptic plasticity of the visual cortex in VAD rats by regulating NRXN1, thereby participating in the formation of autistic-like behaviors in VAD rats.