Down-regulation of a signaling mediator in association with lowered plasma arachidonic acid levels in individuals with autism spectrum disorders

Lipid-Based Molecules on Signaling Pathways in Autism Spectrum Disorder

The signaling pathways associated with lipid metabolism contribute to the pathophysiology of autism spectrum disorder (ASD) and provide insights for devising new therapeutic strategies. Prostaglandin E2 is a membrane-derived lipid molecule that contributes to developing ASD associated with canonical Wnt signaling. Cyclooxygenase-2 plays a key role in neuroinflammation and is implicated in the pathogenesis of neurodevelopmental diseases, such as ASD. The endocannabinoid system maintains a balance between inflammatory and redox status and synaptic plasticity and is a potential target for ASD pathophysiology. Redox signaling refers to specific and usually reversible oxidation–reduction reactions, some of which are also involved in pathways accounting for the abnormal behavior observed in ASD. Redox signaling and redox status-sensitive transcription factors contribute to the pathophysiology of ASD. Cannabinoids regulate the redox balance by altering the levels and activity of antioxidant molecules via ROS-producing NADPH oxidase (NOX) and ROS-scavenging superoxide dismutase enzymes. These signaling cascades integrate a broad range of neurodevelopmental processes that may be involved in the pathophysiology of ASD. Based on these pathways, we highlight putative targets that may be used for devising novel therapeutic interventions for ASD.

Identifying genetic determinants of inflammatory pain in mice using a large-scale gene-targeted screen

ABSTRACT

Identifying the genetic determinants of pain is a scientific imperative given the magnitude of the global health burden that pain causes. Here, we report a genetic screen for nociception, performed under the auspices of the International Mouse Phenotyping Consortium. A biased set of 110 single-gene knockout mouse strains was screened for 1 or more nociception and hypersensitivity assays, including chemical nociception (formalin) and mechanical and thermal nociception (von Frey filaments and Hargreaves tests, respectively), with or without an inflammatory agent (complete Freund's adjuvant). We identified 13 single-gene knockout strains with altered nocifensive behavior in 1 or more assays. All these novel mouse models are openly available to the scientific community to study gene function. Two of the 13 genes (Gria1 and Htr3a) have been previously reported with nociception-related phenotypes in genetically engineered mouse strains and represent useful benchmarking standards. One of the 13 genes (Cnrip1) is known from human studies to play a role in pain modulation and the knockout mouse reported herein can be used to explore this function further. The remaining 10 genes (Abhd13, Alg6, BC048562, Cgnl1, Cp, Mmp16, Oxa1l, Tecpr2, Trim14, and Trim2) reveal novel pathways involved in nociception and may provide new knowledge to better understand genetic mechanisms of inflammatory pain and to serve as models for therapeutic target validation and drug development.

Plasma and red blood cell n3 fatty acids correlate positively with the WISC-R verbal and full-scale intelligence quotients and inversely with Conner's parent-rated ADHD index t-scores in children with high functioning autism and Asperger's syndrome

Findings of the fatty acid status of people with autism spectrum disorders have been incongruent perhaps because of the diversity of the condition. A cross-sectional design study was used to  investigated fatty acid levels and relationships between fatty acids, and cognition and behaviour in a homogenous group of children with autism spectrum disorder. Children with Asperger's syndrome (AS) /high functioning autism (n = 44) and healthy siblings (n = 17) were recruited from the Diagnostic and Therapeutic Centre for Children with Autism, Warsaw, Poland. In the AS group, plasma phosphatidylcholine 22:5n3 correlated positively with verbal (r = 0.357, p = 0.019) and full scale (r = 0.402, p = 0.008) IQs, red blood cell phosphatidylcholine 22:5n3 with verbal (r = 0.308, p = 0.044), performance (r = 0.304, p = 0.047) and full scale (r = 0.388, p = 0.011) IQs and red blood cell phosphatidylethanolamine 22:5n3 with verbal (r = 0.390, p = 0.010) and full scale (r = 0.370, p = 0.016) IQs. Whilst, plasma phosphatidycholine 20:5n3 (r = -0.395, p = 0.009), 22:6n3 (r = -0.402, p = 0.007) and total n3 fatty acids (r = -425, p = 0.005), red blood cell phosphatidlycholine 20:5n3 (r = -0.321, p = 0.036) and red blood cell phosphatidylethanolamine 20:5n3 (r = -0.317, p = 0.038), 22:6n3 (r = -0.297, p = 0.05) and total n3 fatty acids (r = -0.306, p = 0.046) correlated inversly with ADHD index. Similarly, inattention was negatively related with plasma phosphatidylcholine 22:6n3 (r = -0.335, p = 0.028), and total n3 fatty acids (r = -0.340, p = 0.026), oppositional with plasma phosphatidylcholine 18:3n3 (r = -0.333, p = 0.029), 20:5n3 (r = -0.365, p = 0.016), total n3 fatty acids (r = -0.293, p < 0.05), red blood cell phosphatidylcholine 18:3n3 (r = -0.337, p = 0.027) and red blood cell ethanolamine 18:3n3 (r = - 0.333, p = 0.029), 20:5n3 (r = -0.328, p = 0.032), 22:6n3 (r = 0.362, p = 0.017) and total n-3 fatty acids (r = -0.298, p < 0.05) and hyperactivity with plasma phosphatidylcholine 22:6n3 (r = -0.320, p = 0.039). In contrast, there were inverse correlations between red blood cell phosphatidylcholine 18:2n6 and performance (r = -0.358, p = 0.019) and full scale (r = -0.320, p = 0.039) IQs, and direct correlations between red blood cell phosphatidylcholine 22:4n6 (r = 0.339, p = 0.026) and 22:5n6 (r = 0.298, p < 0.05) and ADHD index, between red blood cell phosphatidylcholine 22:4n6 (r = 0.308, p = 0.044) and inattention, between plasma phosphatidylcholine 22:4n6 (r = 0.341, p = 0.025), red blood cell phosphatidylcholine 20:4n6 (r = 0.314, p = 0.041) and total n6 fatty acids (r = 0.336, p = 0.028) and oppositional and plasma phosphatidylcholine 20:3n6 (r = 0.362, p = 0.018) and red blood cell phosphatidylcholine 20:3n6 (r = 0.401, p = 0.009) and hyperactivity. The findings of the ethnically homogenous children with Asperger's syndrome/high functioning autism study revealed positive associations between 22:5n3 and cognition, and negative relationships between 20:5n3 and 22:6n3 and behavioural problem. In contrast, cognitive ability and behavioural problems were negatively and positively associated with n6 fatty acids. Further investigation is required to establish whether there a cause and effect relationship. Regardless, it would be prudent to ensure that children with the conditions have optimum n3 PUFA intake.

Dietary rescue of adult behavioral deficits in the Fmr1 knockout mouse

The current study aimed to further address important questions regarding the therapeutic efficacy of omega-3 fatty acids for various behavioral and neuroimmune aspects of the Fmr1 phenotype. To address these questions, our experimental design utilized two different omega-3 fatty acid administration timepoints, compared to both standard laboratory chow controls ("Standard") and a diet controlling for the increase in fat content ("Control Fat"). In the first paradigm, post-weaning supplementation (after postnatal day 21) with the omega-3 fatty acid diet ("Omega-3") reversed deficits in startle threshold, but not deficits in prepulse inhibition, and the effect on startle threshold was not specific to the Omega-3 diet. However, post-weaning supplementation with both experimental diets also impaired acquisition of a fear response, recall of the fear memory and contextual fear conditioning compared to the Standard diet. The post-weaning Omega-3 diet reduced hippocampal expression of IL-6 and this reduction of IL-6 was significantly associated with diminished performance in the fear conditioning task. In the perinatal experimental paradigm, the Omega-3 diet attenuated hyperactivity and acquisition of a fear response. Additionally, perinatal exposure to the Control Fat diet (similar to a "Western" diet) further diminished nonsocial anxiety in the Fmr1 knockout. This study provides significant evidence that dietary fatty acids throughout the lifespan can significantly impact the behavioral and neuroimmune phenotype of the Fmr1 knockout model.

Altered Metabolic Characteristics in Plasma of Young Boys with Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a serious neurodevelopmental disorder with no clinical biomarker. This study used untargeted metabolomic analysis to identify metabolic characteristics in plasma that can distinguish ASD children. 29 boys with ASD (3.02 ± 0.67 years) and 30 typically developing (TD) boys (3.13 ± 0.46 years) were recruited. Developmental and behavioral assessments were conducted in ASD group. Samples of plasma were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The association between metabolite concentration and scale score was assessed by Spearman rank correlation. Altered metabolic characteristics were found in boys with ASD. In Receiver Operating Characteristic (ROC) analysis, ornithine had the highest AUC (Area under ROC) value. Furthermore, the concentration of choline and ornithine was negatively correlated with ABC-language score in ASD group.

The Role of Cholesterol and Fatty Acids in the Etiology and Diagnosis of Autism Spectrum Disorders

Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders whose pathogenesis seems to be related to an imbalance of excitatory and inhibitory synapses, which leads to disrupted connectivity during brain development. Among the various biomarkers that have been evaluated in the last years, metabolic factors represent a bridge between genetic vulnerability and environmental aspects. In particular, cholesterol homeostasis and circulating fatty acids seem to be involved in the pathogenesis of ASDs, both through the contribute in the stabilization of cell membranes and the modulation of inflammatory factors. The purpose of the present review is to summarize the available data about the role of cholesterol and fatty acids, mainly long-chain ones, in the onset of ASDs. A bibliographic research on the main databases was performed and 36 studies were included in our review. Most of the studies document a correlation between ASDs and hypocholesterolemia, while the results concerning circulating fatty acids are less univocal. Even though further studies are necessary to confirm the available data, the metabolic biomarkers open to new treatment options such as the modulation of the lipid pattern through the diet.

Urinary and Plasma Antioxidants in Behavioral Symptoms of Individuals With Autism Spectrum Disorder

The balance between antioxidant capacity and oxidative stress-induced free radicals may be crucial in the pathophysiological development factor of autism spectrum disorder (ASD). We measured the following urinary and plasma biomarker levels of oxidative stress and antioxidants. As urinary biomarkers, (1) hexanoyl-lysine (HEL), which is a new biomarker of oxidative stress, (2) the total antioxidant capacity (TAC), and (3) 8-hydroxy-2'-deoxyguanosine (8-OHdG), as a product of oxidative modifications to DNA; and the plasma levels of (4) the antioxidant protein superoxide dismutase (SOD), which is the crucial defense again oxygen reactive species, and (5) transferrin and (6) ceruloplasmin, which are biomarkers of iron and copper neurotransmission and oxidant-antioxidant systems. We examined the relationship between these urinary and plasma biomarkers and behavioral symptoms in 19 individuals with ASD (mean age, 10.8 ± 5.2 years) and 10 age-matched healthy controls (mean age, 14.2 ± 7.0 years). Behavioral symptoms were estimated using the Aberrant Behavior Checklist (ABC). Urinary TAC levels were significantly lower, whereas urinary HEL levels were significantly increased in the ASD group as compared with the control group. The five ABC subscale and total scores were significantly raised in the autism group than in the control group. The results of a linear regression analysis revealed that plasma SOD levels may be a more accurate predictor of differences in ABC scores between individuals with ASD and control individuals. The present study firstly revealed the important findings that the cooperation between the urinary antioxidant TAC and plasma SOD levels may contribute to the ABC subscale scores of stereotypy. Urinary TAC activity and antioxidant protein SOD may be associated with incomplete mineral body store and antioxidant-related transcription factor and browning reactions. Consequently, a critical imbalance between TAC urinary levels and plasma SOD levels may be an important contributor to autistic behavioral symptoms.

Deciphering biochemical basis of Qingkailing injection-induced anaphylaxis in a rat model by time-dependent metabolomic profiling based on metabolite polarity-oriented analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Qingkailing injection (QKLI) is prepared from eight traditional Chinese medicinal materials or their extracts, which is widely used in clinical practice to treat the upper respiratory inflammation, pneumonia, high fever and viral encephalitis, nonetheless, suffering from serious anaphylaxis.

AIM OF STUDY

This study aims to develop an integrative metabolomics approach for deciphering the biochemical basis of QKLI induced anaphylaxis (QKLI-IA).

MATERIALS AND METHODS

The accuracy of animal modeling, the coverage of detected metabolites and the timeliness of pathological reaction are three key factors for revealing the biochemical basis of disease with untargeted metabolomics. In this study, firstly, the allergic rats (responders) were first screened by passive cutaneous anaphylaxis experiment and then were utilized for modeling. To cover a wider range of metabolites, a large-scale untargeted metabolomics based on metabolites polarity-oriented analysis was performed using ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Then, to evaluate the timeliness of QKLI-IA, a time-dependent metabolomic profiling including the early, mid and late anaphylaxis stages of QKLI-IA, was performed.

RESULTS

Corresponding to early, mid and late anaphylaxis stages of QKLI-IA, 14, 9 and 4 potential biomarkers were identified, respectively. Metabolism pathway analysis revealed that QKLI-IA resulted in dynamic changes in serum amino acid, fatty acid, glycerolipid, and phospholipid metabolisms. Twenty-four metabolites were found with identical fluctuating trends across the three stages of QKLI-IA. The results indicate that the pathogenesis of QKLI-IA is closely related to arachidonic acid metabolism.

CONCLUSION

This research provides a methodology reference for revealing the biochemical basis of disease using metabolomic profiling and offers a new insight to understand the pathogenesis of QKLI-IA.

Understanding environmental contributions to autism: Causal concepts and the state of science

The complexity of neurodevelopment, the rapidity of early neurogenesis, and over 100 years of research identifying environmental influences on neurodevelopment serve as backdrop to understanding factors that influence risk and severity of autism spectrum disorder (ASD). This Keynote Lecture, delivered at the May 2016 annual meeting of the International Society for Autism Research, describes concepts of causation, outlines the trajectory of research on nongenetic factors beginning in the 1960s, and briefly reviews the current state of this science. Causal concepts are introduced, including root causes; pitfalls in interpreting time trends as clues to etiologic factors; susceptible time windows for exposure; and implications of a multi-factorial model of ASD. An historical background presents early research into the origins of ASD. The epidemiologic literature from the last fifteen years is briefly but critically reviewed for potential roles of, for example, air pollution, pesticides, plastics, prenatal vitamins, lifestyle and family factors, and maternal obstetric and metabolic conditions during her pregnancy. Three examples from the case-control CHildhood Autism Risks from Genes and the Environment Study are probed to illustrate methodological approaches to central challenges in observational studies: capturing environmental exposure; causal inference when a randomized controlled clinical trial is either unethical or infeasible; and the integration of genetic, epigenetic, and environmental influences on development. We conclude with reflections on future directions, including exposomics, new technologies, the microbiome, gene-by-environment interaction in the era of -omics, and epigenetics as the interface of those two. As the environment is malleable, this research advances the goal of a productive and fulfilling life for all children, teen-agers and adults. Autism Res 2018, 11: 554-586. © 2018 International Society for Autism Research, Wiley Periodicals, Inc.

LAY SUMMARY

This Keynote Lecture, delivered at the 2016 meeting of the International Society for Autism Research, discusses evidence from human epidemiologic studies of prenatal factors contributing to autism, such as pesticides, maternal nutrition and her health. There is no single cause for autism. Examples highlight the features of a high-quality epidemiology study, and what comprises a compelling case for causation. Emergent research directions hold promise for identifying potential interventions to reduce disabilities, enhance giftedness, and improve lives of those with ASD.

Erythrocyte fatty acid profiles in children are not predictive of autism spectrum disorder status: a case control study

Biomarkers promise biomolecular explanations as well as reliable diagnostics, stratification, and treatment strategies that have the potential to help mitigate the effects of disorders. While no reliable biomarker has yet been found for autism spectrum disorder (ASD), fatty acids have been investigated as potential biomarkers because of their association with brain development and neural functions. However, the ability of fatty acids to classify individuals with ASD from age/gender-matched neurotypical (NEU) peers has largely been ignored in favor of investigating population-level differences. Contrary to existing work, this classification task between ASD and NEU cohorts is the main focus of this work. The data presented herein suggest that fatty acids do not allow for classification at the individual level.

Interplay Between Peripheral and Central Inflammation in Autism Spectrum Disorders: Possible Nutritional and Therapeutic Strategies

Pre- and post-natal factors can affect brain development and function, impacting health outcomes with particular relevance to neurodevelopmental diseases, such as autism spectrum disorders (ASDs). Maternal obesity and its associated complications have been related to the increased risk of ASDs in offspring. Indeed, animals exposed to maternal obesity or high fat diets are prone to social communication impairment and repetitive behavior, the hallmarks of autism. During development, fatty acids and sugars, as well as satiety hormones, like insulin and leptin, and inflammatory factors related to obesity-induced low grade inflammation, could play a role in the impairment of neuroendocrine system and brain neuronal circuits regulating behavior in offspring. On the other side, post-natal factors, such as mode of delivery, stress, diet, or antibiotic treatment are associated to a modification of gut microbiota composition, perturbing microbiota-gut-brain axis. Indeed, the interplay between the gastrointestinal tract and the central nervous system not only occurs through neural, hormonal, and immune pathways, but also through microbe-derived metabolic products. The modification of unhealthy perinatal and postnatal environment, manipulation of gut microbiota, nutritional, and dietary interventions could represent possible strategies in preventing or limiting ASDs, through targeting inflammatory process and gut microbiota.

Mice Deficient in lysophosphatidic acid acyltransferase delta (Lpaatδ)/acylglycerophosphate acyltransferase 4 (Agpat4) Have Impaired Learning and Memory

We previously characterized LPAATδ/AGPAT4 as a mitochondrial lysophosphatidic acid acyltransferase that regulates brain levels of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylinositol (PI). Here, we report that Lpaatδ^-/- mice display impaired spatial learning and memory compared to wild-type littermates in the Morris water maze and our investigation of potential mechanisms associated with brain phospholipid changes. Marker protein immunoblotting suggested that the relative brain content of neurons, glia, and oligodendrocytes was unchanged. Relative abundance of the important brain fatty acid docosahexaenoic acid was also unchanged in phosphatidylserine, phosphatidylglycerol, and cardiolipin, in agreement with prior data on PC, PE and PI. In phosphatidic acid, it was increased. Specific decreases in ethanolamine-containing phospholipids were detected in mitochondrial lipids, but the function of brain mitochondria in Lpaatδ^-/- mice was unchanged. Importantly, we found that Lpaatδ^-/- mice have a significantly and drastically lower brain content of the N-methyl-d-asparate (NMDA) receptor subunits NR1, NR2A, and NR2B, as well as the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunit GluR1, compared to wild-type mice. However, general dysregulation of PI-mediated signaling is not likely responsible, since phospho-AKT and phospho-mTOR pathway regulation was unaffected. Our findings indicate that Lpaatδ deficiency causes deficits in learning and memory associated with reduced NMDA and AMPA receptors.

Potential Benefits of Ameliorating Metabolic and Nutritional Abnormalities in People With Profound Developmental Disabilities

Background:

People with profound developmental disabilities have some of the most severe neurological impairments seen in society, have accelerated mortality due to huge medical challenges, and yet are often excluded from scientific studies. They actually have at least 2 layers of conditions: (1) the original disability and (2) multiple under-recognized and underexplored metabolic and nutritional imbalances involving minerals (calcium, zinc, and selenium), amino acids (taurine, tryptophan), fatty acids (linoleic acid, docosahexaenoic acid, arachidonic acid, adrenic acid, Mead acid, plasmalogens), carnitine, hormones (insulinlike growth factor 1), measures of oxidative stress, and likely other substances and systems.

Summary:

This review provides the first list of metabolic and nutritional abnormalities commonly found in people with profound developmental disabilities and, based on the quality of life effects of similar abnormalities in neurotypical people, indicates the potential effects of these abnormalities in this population which often cannot communicate symptoms.

Key messages:

We propose that improved understanding and management of these disturbed mechanisms would enhance the quality of life of people with profound developmental disabilities. Such insights may also apply to people with other conditions associated with disability, including some diseases requiring stem cell implantation and living in microgravity.

The rs251684 Variant of PLA2G4C Is Associated with Autism Spectrum Disorder in the Northeast Han Chinese Population

AIM

To investigate the association between autism spectrum disorder (ASD) and the phospholipase A2 group IVC (PLA2G4C) and phospholipase A2 group XIIA (PLA2G12A) polymorphisms in the Northeast Han Chinese population.

MATERIALS AND METHODS

A total of 68 family trios (children diagnosed with ASD and their unaffected parents) were enrolled. Five single-nucleotide polymorphisms (SNPs) (rs9226, rs1045376, rs251684, rs2307279, and rs156631) in PLA2G4C and four SNPs (rs6533451, rs2285714, rs2285713, and rs11728699) in PLA2G12A were selected and genotyped. The association between the SNPs and ASD was analyzed using the transmission disequilibrium test.

RESULTS

Our results showed a significant association between ASD and the rs251684 variant of PLA2G4C (transmitted/nontransmitted = 36/21, χ² = 3.947, p = 0.047), but no association between ASD and the other eight SNPs investigated (all p > 0.05). Moreover, we found no preference in the transmission of haplotypes constructed for either PLA2G4C or PLA2G12A.

CONCLUSION

The rs251684 polymorphism of PLA2G4C may be associated with ASD risk.

Chemicals, Nutrition, and Autism Spectrum Disorder: A Mini-Review

The rapid increase of the prevalence of autism spectrum disorder (ASD) suggests that exposure to chemicals may impact the development of ASD. Therefore, we reviewed literature on the following chemicals, nutrient to investigate their association with ASD: (1) smoke/tobacco, (2) alcohol, (3) air pollution, (4) pesticides, (5) endocrine-disrupting chemicals, (6) heavy metals, (7) micronutrients, (8) fatty acid, and (9) parental obesity as a proxy of accumulation of specific chemicals or nutritional status. Several chemical exposures such as air pollution (e.g., particular matter 2.5), pesticides, bisphenol A, phthalates, mercury, and nutrition deficiency such as folic acid, vitamin D, or fatty acid may possibly be associated with an increased risk of ASD, whereas other traditional risk factors such as smoking/tobacco, alcohol, or polychlorinated biphenyls are less likely to be associated with ASD. Further research is needed to accumulate evidence on the association between chemical exposure and nutrient deficiencies and ASD in various doses and populations.