SNP analyses of growth factor genes EGF, TGFβ-1, and HGF reveal haplotypic association of EGF with autism

Genetics of environmental sensitivity to psychiatric and neurodevelopmental phenotypes: evidence from GWAS of monozygotic twins

Individual sensitivity to environmental exposures may be genetically influenced. This genotype-by-environment interplay implies differences in phenotypic variance across genotypes. However, environmental sensitivity genetic variants have proven challenging to detect. GWAS of monozygotic twin differences is a family-based variance analysis method, which is more robust to systemic biases that impact population-based methods. We combined data from up to 21,792 monozygotic twins (10,896 pairs) from 11 studies to conduct the largest GWAS meta-analysis of monozygotic phenotypic differences in children and adolescents/adults for seven psychiatric and neurodevelopmental phenotypes: attention deficit hyperactivity disorder (ADHD) symptoms, autistic traits, anxiety and depression symptoms, psychotic-like experiences, neuroticism, and wellbeing. The SNP-heritability of variance in these phenotypes were estimated (h2: 0% to 18%), but were imprecise. We identified a total of 13 genome-wide significant associations (SNP, gene, and gene-set), including genes related to stress-reactivity for depression, growth factor-related genes for autistic traits and catecholamine uptake-related genes for psychotic-like experiences. Monozygotic twins are an important new source of evidence about the genetics of environmental sensitivity.

Biopsychological correlates of repetitive and restricted behaviors in autism spectrum disorders

BACKGROUND

Autism Spectrum Disorder (ASD) is considered a neurodevelopmental condition that is characterized by alterations in social interaction and communication, as well as patterns of restrictive and repetitive behaviors (RRBs). RRBs are defined as broad behaviors that comprise stereotypies, insistence on sameness, and attachment to objects or routines. RRBs can be divided into lower-level behaviors (motor, sensory, and object-manipulation behaviors) and higher-level behaviors (restrictive interests, insistence on sameness, and repetitive language). According to the DSM-5, the grade of severity in ASD partially depends on the frequency of RRBs and their consequences for disrupting the life of patients, affecting their adaptive skills, and increasing the need for parental support.

METHODS

We conducted a systematic review to examine the biopsychological correlates of the symptomatic domains of RRBs according to the type of RRBs (lower- or higher-level). We searched for articles from the National Library of Medicine (PubMed) using the terms: autism spectrum disorders, ASD, and autism-related to executive functions, inhibitory control, inflexibility, cognitive flexibility, hyper or hypo connectivity, and behavioral approaches. For describing the pathophysiological mechanism of ASD, we also included animal models and followed PRISMA guidelines.

RESULTS

One hundred and thirty-one articles were analyzed to explain the etiology, continuance, and clinical evolution of these behaviors observed in ASD patients throughout life.

CONCLUSIONS

Biopsychological correlates involved in the origin of RRBs include alterations in a) neurotransmission system, b) brain volume, c) inadequate levels of growth factors, d) hypo- or hyper-neural connectivity, e) impairments in behavioral inhibition, cognitive flexibility, and monitoring and f) non-stimulating environments. Understanding these lower- and higher-level of RRBs can help professionals to improve or design novel therapeutic strategies.

Neuron-Glia Interactions in Tuberous Sclerosis Complex Affect the Synaptic Balance in 2D and Organoid Cultures

Tuberous sclerosis complex (TSC) is a genetic disease affecting the brain. Neurological symptoms like epilepsy and neurodevelopmental issues cause a significant burden on patients. Both neurons and glial cells are affected by TSC mutations. Previous studies have shown changes in the excitation/inhibition balance (E/I balance) in TSC. Astrocytes are known to be important for neuronal development, and astrocytic dysfunction can cause changes in the E/I balance. We hypothesized that astrocytes affect the synaptic balance in TSC. TSC patient-derived stem cells were differentiated into astrocytes, which showed increased proliferation compared to control astrocytes. RNA sequencing revealed changes in gene expression, which were related to epidermal growth factor (EGF) signaling and enriched for genes that coded for secreted or transmembrane proteins. Control neurons were cultured in astrocyte-conditioned medium (ACM) of TSC and control astrocytes. After culture in TSC ACM, neurons showed an altered synaptic balance, with an increase in the percentage of VGAT⁺ synapses. These findings were confirmed in organoids, presenting a spontaneous 3D organization of neurons and glial cells. To conclude, this study shows that TSC astrocytes are affected and secrete factors that alter the synaptic balance. As an altered E/I balance may underlie many of the neurological TSC symptoms, astrocytes may provide new therapeutic targets.

Epidermal growth factor signals attenuate phenotypic and functional development of neocortical GABA neurons

Phenotypic development of neocortical GABA neurons is highly plastic and promoted by various neurotrophic factors such as neuregulin-1. A subpopulation of GABA neurons expresses not only neuregulin receptor (ErbB4) but also epidermal growth factor (EGF) receptor (ErbB1) during development, but the neurobiological action of EGF on this cell population is less understood than that of neuregulin-1. Here, we examined the effects of exogenous EGF on immature GABA neurons both in culture and in vivo and also explored physiological consequences in adults. We prepared low density cultures from the neocortex of rat embryos and treated neocortical neurons with EGF. EGF decreased protein levels of glutamic acid decarboxylases (GAD65 and GAD67), and EGF influences on neuronal survival and glial proliferation were negligible or limited. The EGF treatment also diminished the frequency of miniature inhibitory postsynaptic currents (mIPSCs). In vivo administration of EGF to mouse pups reproduced the above GABAergic phenomena in neocortical culture. In EGF-injected postnatal mice, GAD- and parvalbumin-immunoreactivities were reduced in the frontal cortex. In addition, postnatal EGF treatment decreased mIPSC frequency in, and the density of, GABAergic terminals on pyramidal cells. Although these phenotypic influences on GABA neurons became less marked during development, it later resulted in the reduced β- and γ-powers of sound-evoked electroencephalogram in adults, which is regulated by parvalbumin-positive GABA neurons and implicated in the schizophrenia pathophysiology. These findings suggest that, in contrast to the ErbB4 ligand of neuregulin-1, the ErbB1 ligand of EGF exerts unique maturation-attenuating influences on developing cortical GABAergic neurons.

Bio-collections in autism research

Autism spectrum disorder (ASD) is a group of complex neurodevelopmental disorders with diverse clinical manifestations and symptoms. In the last 10 years, there have been significant advances in understanding the genetic basis for ASD, critically supported through the establishment of ASD bio-collections and application in research. Here, we summarise a selection of major ASD bio-collections and their associated findings. Collectively, these include mapping ASD candidate genes, assessing the nature and frequency of gene mutations and their association with ASD clinical subgroups, insights into related molecular pathways such as the synapses, chromatin remodelling, transcription and ASD-related brain regions. We also briefly review emerging studies on the use of induced pluripotent stem cells (iPSCs) to potentially model ASD in culture. These provide deeper insight into ASD progression during development and could generate human cell models for drug screening. Finally, we provide perspectives concerning the utilities of ASD bio-collections and limitations, and highlight considerations in setting up a new bio-collection for ASD research.

Serum and cerebrospinal fluid immune mediators in children with autistic disorder: a longitudinal study

BACKGROUND

The causes of autism likely involve genetic and environmental factors that influence neurobiological changes and the neurological and behavioral features of the disorder. Immune factors and inflammation are hypothesized pathogenic influences, but have not been examined longitudinally.

METHODS

In a cohort of 104 participants with autism, we performed an assessment of immune mediators such as cytokines, chemokines, or growth factors in serum and cerebrospinal fluid (n = 67) to determine potential influences of such mediators in autism.

RESULTS

As compared with 54 typically developing controls, we found no evidence of differences in the blood profile of immune mediators supportive of active systemic inflammation mechanisms in participants with autism. Some modulators of immune function (e.g., EGF and soluble CD40 ligand) were increased in the autism group; however, no evidence of group differences in traditional markers of active inflammation (e.g., IL-6, TNFα, IL-1β) were observed in the serum. Further, within-subject stability (measured by estimated intraclass correlations) of most analytes was low, indicating that a single measurement is not a reliable prospective indicator of concentration for most analytes. Additionally, in participants with autism, there was little correspondence between the blood and CSF profiles of cytokines, chemokines, and growth factors, suggesting that peripheral markers may not optimally reflect the immune status of the central nervous system. Although the relatively high fraction of intrathecal production of selected chemokines involved in monocyte/microglia function may suggest a possible relationship with the homeostatic role of microglia, control data are needed for further interpretation of its relevance in autism.

CONCLUSIONS

These longitudinal observations fail to provide support for the hypothesized role of disturbances in the expression of circulating cytokines and chemokines as an indicator of systemic inflammation in autism. ClinicalTrials.gov, NCT00298246.

Alterations of Growth Factors in Autism and Attention-Deficit/Hyperactivity Disorder

Growth factors (GFs) are cytokines that regulate the neural development. Recent evidence indicates that alterations in the expression level of GFs during embryogenesis are linked to the pathophysiology and clinical manifestations of attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorders (ASD). In this concise review, we summarize the current evidence that supports the role of brain-derived neurotrophic factor, insulin-like growth factor 2, hepatocyte growth factor (HGF), glial-derived neurotrophic factor, nerve growth factor, neurotrophins 3 and 4, and epidermal growth factor in the pathogenesis of ADHD and ASD. We also highlight the potential use of these GFs as clinical markers for diagnosis and prognosis of these neurodevelopmental disorders.

Transforming growth factor-β1 (C509T, G800A, and T869C) gene polymorphisms and risk of ischemic stroke in North Indian population: A hospital-based case-control study

Background:

Transforming growth factor-beta 1 (TGF-β1) is a multifunctional pleiotropic cytokine involved in inflammation and pathogenesis of cerebrovascular diseases. There is limited information on the association between variations within the TGF-β1 gene polymorphisms and risk of ischemic stroke (IS). The aim of this study was to investigate the association of the TGF-β1 gene (C509T, G800A, and T869C) polymorphisms, and their haplotypes with the risk of IS in North Indian population.

Methods:

A total of 250 IS patients and 250 age- and sex-matched controls were studied. IS was classified using the Trial of Org 10172 in Acute Stroke Treatment classification. Conditional logistic regression analysis was used to calculate the strength of association between TGF-β1 gene polymorphisms and risk of IS. Genotyping was performed using SNaPshot method.

Results:

Hypertension, diabetes, dyslipidemia, alcohol, smoking, family history of stroke, sedentary lifestyle, and low socioeconomic status were found to be associated with the risk of IS. The distribution of C509T, G800A and T869C genotypes was consistent with Hardy-Weinberg Equilibrium in the IS and control groups. Adjusted conditional logistic regression analysis showed a significant association of TGF-β1 C509T (odds ratio [OR], 2.1; 95% CI; 1.2–3.8; P = 0.006), G800A (OR, 4.4; 95% CI; 2.1–9.3; P < 0.001) and T869C (OR, 2.6; 95% CI; 1.5–4.5; P = 0.001) with the risk of IS under dominant model. Haplotype analysis showed that C509-A800-T869 and T509-G800-C869 haplotypes were significantly associated with the increased risk of IS. C509T and T869C were in strong linkage disequilibrium (D' =0.51, r² = 0.23).

Conclusion:

Our results suggest that TGF-β1 polymorphisms and their haplotypes are significantly associated with the risk of IS in North Indian population.

Association study of functional polymorphisms in interleukins and interleukin receptors genes: IL1A, IL1B, IL1RN, IL6, IL6R, IL10, IL10RA and TGFB1 in schizophrenia in Polish population

Schizophrenia has been associated with a large range of autoimmune diseases, with a history of any autoimmune disease being associated with a 45% increase in risk for the illness. The inflammatory system may trigger or modulate the course of schizophrenia through complex mechanisms influencing neurodevelopment, neuroplasticity and neurotransmission. In particular, increases or imbalance in cytokine before birth or during the early stages of life may affect neurodevelopment and produce vulnerability to the disease. A total of 27 polymorphisms of IL1N gene: rs1800587, rs17561; IL1B gene: rs1143634, rs1143643, rs16944, rs4848306, rs1143623, rs1143633, rs1143627; IL1RN gene: rs419598, rs315952, rs9005, rs4251961; IL6 gene: rs1800795, rs1800797; IL6R gene: rs4537545, rs4845617, rs2228145, IL10 gene: rs1800896, rs1800871, rs1800872, rs1800890, rs6676671; IL10RA gene: rs2229113, rs3135932; TGF1B gene: rs1800469, rs1800470; each selected on the basis of molecular evidence for functionality, were investigated in this study. Analysis was performed on a group of 621 patients with diagnosis of schizophrenia and 531 healthy controls in Polish population. An association of rs4848306 in IL1B gene, rs4251961 in IL1RN gene, rs2228145 and rs4537545 in IL6R with schizophrenia have been observed. rs6676671 in IL10 was associated with early age of onset. Strong linkage disequilibrium was observed between analyzed polymorphisms in each gene, except of IL10RA. We observed that haplotypes composed of rs4537545 and rs2228145 in IL6R gene were associated with schizophrenia. Analyses with family history of schizophrenia, other psychiatric disorders and alcohol abuse/dependence did not show any positive findings. Further studies on larger groups along with correlation with circulating protein levels are needed.

Decreased Phosphorylated Protein Kinase B (Akt) in Individuals with Autism Associated with High Epidermal Growth Factor Receptor (EGFR) and Low Gamma-Aminobutyric Acid (GABA)

Dysregulation of the PI3K/AKT/mammalian target of rapamycin (mTOR) pathway could contribute to the pathogenesis of autism spectrum disorders. In this study, phosphorylated Akt concentration was measured in 37 autistic children and 12, gender and age similar neurotypical, controls using an enzyme-linked immunosorbent assay. Akt levels were compared to biomarkers known to be associated with epidermal growth factor receptor (EGFR) and c-Met (hepatocyte growth factor (HGF) receptor) pathways and severity levels of 19 autism-related symptoms. We found phosphorylated Akt levels significantly lower in autistic children and low Akt levels correlated with high EGFR and HGF and low gamma-aminobutyric acid, but not other biomarkers. Low Akt levels also correlated significantly with increased severity of receptive language, conversational language, hypotonia, rocking and pacing, and stimming, These results suggest a relationship between decreased phosphorylated Akt and selected symptom severity in autistic children and support the suggestion that the AKT pathways may be associated with the etiology of autism.

A decade from discovery to therapy: Lingo-1, the dark horse in neurological and psychiatric disorders

Leucine-rich repeat and immunoglobulin domain-containing protein (Lingo-1) is a potent negative regulator of neuron and oligodendrocyte survival, neurite extension, axon regeneration, oligodendrocyte differentiation, axonal myelination and functional recovery; all processes highly implicated in numerous brain-related functions. Although playing a major role in developmental brain functions, the potential application of Lingo-1 as a therapeutic target for the treatment of neurological disorders has so far been under-estimated. A number of preclinical studies have shown that various methods of antagonizing Lingo-1 results in neuronal and oligodendroglial survival, axonal growth and remyelination; however to date literature has only detailed applications of Lingo-1 targeted therapeutics with a focus primarily on myelination disorders such as multiple sclerosis and spinal cord injury; omitting important information regarding Lingo-1 signaling co-factors. Here, we provide for the first time a complete and thorough review of the implications of Lingo-1 signaling in a wide range of neurological and psychiatric disorders, and critically examine its potential as a novel therapeutic target for these disorders.

The low levels of circulating hepatocyte growth factor in nephrolithiasis cases: independent from gene polymorphism

Environmental and genetic factors are important in development of nephrolithiasis. In a recent study, it has been demonstrated that hepatocyte growth factor (HGF) has an anti-apoptotic effect and thus can reduce the adhesion of calcium oxalate monohydrate crystals to renal epithelial cells. The aim of this study was to evaluate the HGF serum levels and its two gene polymorphisms and possible association of the two in patients with nephrolithiasis. One hundred and five patients with nephrolithiasis and 70 healthy volunteers with similar demographic features were included in this study. Serum HGF levels were measured, and HGF intron 13 C>A (in 102 stone patients and 68 healthy subjects) and intron 14 T>C (in 99 stone patients and 56 healthy subjects) polymorphisms were determined using real-time polymerase chain reaction with TaqMan allelic discrimination method. There were no statistically significant differences in HGF intron 13 C>A and intron 14 T>C polymorphisms between the control and patient groups (X (2) = 1.72 df = 2; p = 0.42, and X (2) = 0.68 df = 2; p = 0.71, respectively). Mean serum HGF concentration was significantly lower in the stone disease patients than in the control subjects (1.05 ± 0.63 pg/mL and 1.35 ± 0.58 ng/mL respectively, p = 0.0001). When allele distribution frequency between stone patients and healthy subjects was compared, there were no significant differences in intron 13 and intron 14 allele distributions between two groups (p = 0.43 and p = 0.44, respectively). It may be concluded from the findings that decrease in HGF levels may play a role in renal stone formation, independent from gene polymorphisms.

A Convenient and Efficient Method to Enrich and Maintain Highly Proliferative Human Fetal Liver Stem Cells

Pluripotent human hepatic stem cells have broad research and clinical applications, which are, however, restricted by both limited resources and technical difficulties with respect to isolation of stem cells from the adult or fetal liver. In this study, we developed a convenient and efficient method involving a two-step in situ collagenase perfusion, gravity sedimentation, and Percoll density gradient centrifugation to enrich and maintain highly proliferative human fetal liver stem cells (hFLSCs). Using this method, the isolated hFLSCs entered into the exponential growth phase within 10 days and maintained sufficient proliferative activity to permit subculture for at least 20 passages without differentiation. Immunocytochemistry, immunofluorescence, and flow cytometry results showed that these cells expressed stem cell markers, such as c-kit, CD44, epithelial cell adhesion molecule (EpCAM), oval cell marker-6 (OV-6), epithelial marker cytokeratin 18 (CK18), biliary ductal marker CK19, and alpha-fetoprotein (AFP). Gene expression analysis showed that these cells had stable mRNA expression of c-Kit, EpCAM, neural cell adhesion molecule (NCAM), CK19, CK18, AFP, and claudin 3 (CLDN-3) throughout each passage while maintaining low levels of ALB, but with complete absence of cytochrome P450 3A4 (C3A4), phosphoenolpyruvate carboxykinase (PEPCK), telomeric repeat binding factor (TRF), and connexin 26 (CX26) expression. When grown in appropriate medium, these isolated liver stem cells could differentiate into hepatocytes, cholangiocytes, osteoblasts, adipocytes, or endothelial cells. Thus, we have demonstrated a more economical and efficient method to isolate hFLSCs than magnetic-activated cell sorting (MACS). This novel approach may provide an excellent tool to isolate highly proliferative hFLSCs for tissue engineering and regenerative therapies.

Inflammatory cytokines: potential biomarkers of immunologic dysfunction in autism spectrum disorders

Autism is a disorder of neurobiological origin characterized by problems in communication and social skills and repetitive behavior. After more than six decades of research, the etiology of autism remains unknown, and no biomarkers have been proven to be characteristic of autism. A number of studies have shown that the cytokine levels in the blood, brain, and cerebrospinal fluid (CSF) of autistic subjects differ from that of healthy individuals; for example, a series of studies suggests that interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) are significantly elevated in different tissues in autistic subjects. However, the expression of some cytokines, such as IL-1, IL-2, transforming growth factor-β (TGF-β), and granulocyte-macrophage colony-stimulating factor (GM-CSF), is controversial, and different studies have found various results in different tissues. In this review, we focused on several types of proinflammatory and anti-inflammatory cytokines that might affect different cell signal pathways and play a role in the pathophysiological mechanism of autistic spectrum disorders.

Increased Epidermal Growth Factor Receptor (EGFR) Associated with Hepatocyte Growth Factor (HGF) and Symptom Severity in Children with Autism Spectrum Disorders (ASDs)

BACKGROUND

One in 88 children in the US is thought to have one of the autism spectrum disorders (ASDs). ASDs are characterized by social impairments and communication problems. Growth factors and their receptors may play a role in the etiology of ASDs. Research has shown that epidermal growth factor receptor (EGFR) activation is associated with nerve cell development and repair. This study was designed to measure plasma levels of EGFR in autistic children and correlate these levels with its ligand, epidermal growth factor, other related putative biomarkers such as hepatocyte growth factor (HGF), the ligand for MET (MNNG HOS transforming gene) receptor, as well as the symptom severity of 19 different behavioral symptoms.

SUBJECTS AND METHODS

Plasma EGFR concentration was measured in 33 autistic children and 34 age- and gender-similar neurotypical controls, using an enzyme-linked immunosorbent assay. Plasma EGFR levels were compared to putative biomarkers known to be associated with EGFR and MET and severity levels of 19 autism-related symptoms.

RESULTS

We found plasma EGFR levels significantly higher in autistic children, when compared to neurotypical controls. EGFR levels correlated with HGF and high-mobility group protein B1 (HMGB1) levels, but not other tested putative biomarkers, and EGFR levels correlated significantly with severity of expressive language, conversational language, focus/attention, hyperactivity, eye contact, and sound sensitivity deficiencies.

CONCLUSIONS

These results suggest a relationship between increased plasma EGFR levels and designated symptom severity in autistic children. A strong correlation between plasma EGFR and HGF and HMGB1 suggests that increased EGFR levels may be associated with the HGF/Met signaling pathway, as well as inflammation.

Association between Hepatocyte Growth Factor (HGF) Gene Polymorphisms and Serum HGF Levels in Patients with Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by proliferation and insufficient apoptosis of synovial cell, inflammatory cell infiltration, angiogenesis, and destruction of joints. Hepatocyte growth factor (HGF) has many functions, such as regulation of inflammation, angiogenesis, and inhibition of apoptosis. The purpose of this study was to investigate the association between intron 13 C/A and intron 14 T/C HGF gene polymorphisms and serum HGF levels in patients with RA.

MATERIALS AND METHODS

100 patients with RA and 123 healthy controls were included in this study. Serum HGF concentrations were measured using ELISA kit. Gene polymorphisms were determined by allelic discrimination analysis using the real-time PCR method.

RESULTS

HGF levels, frequency of AA genotype and A allele for intron 13 C/A polymorphism and frequency of CC genotype and C allele for intron 14 T/C polymorphism were increased in patients with RA compared to healthy controls. There was no overall associations between genotypes and serum HGF concentrations in both patient and control groups.

CONCLUSION

Our results indicate that HGF protein and gene may play an important role in the etiopathogenesis of RA. However, further studies are required for a better understanding of mechanisms related to the disease process.

Decreased Epidermal Growth Factor (EGF) Associated with HMGB1 and Increased Hyperactivity in Children with Autism

Background

Autism spectrum disorders (ASDs), characterized by impaired social interactions and deficits in verbal and nonverbal communication, are thought to affect 1 in 88 children in the United States. There is much support for the role of growth factors in the etiology of autism. Recent research has shown that epithelial growth factor (EGF) is decreased in young autistic children (2–4 years of age). This study was designed to determine plasma levels of EGF in an older group of autistic children (mean age 10.6 years) and to correlate these EGF levels with putative biomarkers HGF, uPA, uPAR, GAD2, MPO GABA, and HMGB1, as well as symptom severity of 19 different symptoms.

Subjects and methods

Plasma from 38 autistic children, 11 children with pervasive developmental disorder (PDD-NOS) and 40 neurotypical, age and gender similar controls was assessed for EGF concentration using ELISAs. Severity of 19 symptoms (awareness, expressive language, receptive language, (conversational) pragmatic language, focus/attention, hyperactivity, impulsivity, perseveration, fine motor skills, gross motor skills, hypotonia (low muscle tone), tiptoeing, rocking/pacing, stimming, obsessions/fixations, eye contact, sound sensitivity, light sensitivity, and tactile sensitivity) was assessed and then compared to EGF concentrations.

Results

In this study, we found EGF levels in autistic children and those with PDD-NOS to be significantly lower when compared with neurotypical controls. EGF levels correlated with HMGB1 levels but not the other tested putative biomarkers, and EGF correlated negatively with hyperactivity, gross motor skills, and tiptoeing but not other symptoms.

Conclusions

These results suggest an association between decreased plasma EGF levels and selected symptom severity. We also found a strong correlation between plasma EGF and HMGB1, suggesting inflammation is associated with decreased EGF.

Decreased levels of EGF in plasma of children with autism spectrum disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder estimated to affect 1 in 110 children in the U.S., yet the pathology of this disorder is not fully understood. Abnormal levels of several growth factors have been demonstrated in adults with ASD, including epidermal growth factor (EGF) and hepatocyte growth factor (HGF). Both of these growth factors serve important roles in neurodevelopment and immune function. In this study, concentrations of EGF and HGF were assessed in the plasma of 49 children with ASD aged 2–4 years old and 31 typically developing controls of a similar age as part of the Autism Phenome Project (APP). Levels of EGF were significantly reduced in the ASD group compared to typically developing controls (P = 0.003). There were no significant differences in HGF levels in young children with ASD and typically developing controls. EGF plays an important role in regulating neural growth, proliferation, differentiation and migration, and reduced levels of this molecule may negatively impact neurodevelopment in young children with ASD.

Risperidone-related improvement of irritability in children with autism is not associated with changes in serum of epidermal growth factor and interleukin-13

Risperidone has been shown to improve serious behavioral problems in children with autism. Here we asked whether risperidone-associated improvement was related to changes in concentrations of inflammatory molecules in the serum of these subjects. Seven molecules were identified as worthy of further assessment by performing a pilot analysis of 31 inflammatory markers in 21 medication-free subjects with autism versus 15 healthy controls: epidermal growth factor (EGF), interferon-γ (IFN-γ), interleukin (IL)-13, IL-17, monocyte chemoattractant protein-1 (MCP-1), IL-1 and IL-1-receptor antagonist. Serum concentrations of these markers were then established in a different set of subjects that participated in a double-blind, clinical trial and an expanded group of healthy subjects. In the first analysis, samples obtained from subjects with autism at baseline visits were compared to visits after 8-week treatment with placebo (n=37) or risperidone (n=40). The cytokine concentrations remained stable over the 8-week period for both risperidone and placebo groups. In the second analysis, we explored further the differences between medication-free subjects with autism (n=77) and healthy controls (recruited independently; n=19). Serum levels of EGF were elevated in subjects with autism (median=103 pg/mL, n=75) in comparison to healthy controls (75 pg/mL, n=19; p<0.05), and levels of IL-13 were decreased in autism (median=0.8 pg/mL, n=77) in comparison to controls (9.8 pg/mL, n=19; p=0.0003). These changes did not correlate with standardized measures used for a diagnosis of autism. In summary, risperidone-induced clinical improvement in subjects with autism was not associated with changes in the serum inflammatory markers measured. Whether altered levels of EGF and IL-13 play a role in the pathogenesis or phenotype of autism requires further investigation.

The role of neurotrophic factors in autism

Autism spectrum disorders (ASDs) are pervasive developmental disorders that frequently involve a triad of deficits in social skills, communication and language. For the underlying neurobiology of these symptoms, disturbances in neuronal development and synaptic plasticity have been discussed. The physiological development, regulation and survival of specific neuronal populations shaping neuronal plasticity require the so-called 'neurotrophic factors' (NTFs). These regulate cellular proliferation, migration, differentiation and integrity, which are also affected in ASD. Therefore, NTFs have gained increasing attention in ASD research. This review provides an overview and explores the key role of NTFs in the aetiology of ASD. We have also included evidence derived from neurochemical investigations, gene association studies and animal models. By focussing on the role of NTFs in ASD, we intend to further elucidate the puzzling aetiology of these conditions.

Increased serum levels of epidermal growth factor in children with autism

The etiology of autism is unclear, however autism is considered as a multifactorial disorder that is influenced by neurological, environmental, immunological and genetic factors. Growth factors, including epidermal growth factor (EGF), play an important role in the cellular proliferation and the differentiation of the central and peripheral nervous system. In this study we hypothesized that EGF may play a role in the pathophysiology of autism and examined serum EGF levels in children with autism. We measured serum levels of EGF in the 27 autistic children and 28 age- matched normal controls. The serum levels of EGF in the subjects with autism were significantly higher than those of normal control subjects. However, there were no correlations between serum EGF levels and clinical variables in the subjects with autism. This is the first report demonstrating the increased serum levels of EGF in children with autism. This study suggests that increased levels of EGF might have an importance in the pathophysiology of autism.

Autism and immunity: revisited study

Autism spectrum disorder is of interest neurochemically because it represents a relatively homogeneous disorder with regard to disease development, abnormal cognitive development and intellectual development disturbance. A consistent finding in autistic children is a high number of mast cells and a high level of serotonin which is also found at elevated concentrations in the urine of autistic patients. In addition, a dysfunction of clinical conditions, such as gastrointestinal and immunological symptoms, is frequently noted in autistic children, however, IgE does not appear to be prevalent in these children but probably an increase of cytokines/chemokines produced by mast cells at an early age may play an important role. Therefore an immune hypothesis, involving also autoimmunity, is one possible pathogenetic mechanism in autism. In conclusion, mast cell activation could contribute to immune and neuroinflammatory abnormalities that are evident in patients with autism spectrum disorders.

A review of recent reports on autism: 1000 studies published in 2007

From 1000 studies published in 2007 on all aspects of autism, those that reached clear conclusions or included quantitative data were selected for this review. Possible etiologies include elemental metals, especially the inconsistent evidence regarding mercury from the vaccine preservative thimerosal, not used after 2001, and chromosomes and genes with the conclusion that autism has a complex genetic architecture. Also, various parental conditions are considered, as are many different abnormalities in the central nervous system, especially underconnectivity within the cortex. Furthermore, deficiencies in mirror neurons have been proposed, leading to the "theory of mind" explanation that autistic children tend to disregard others. In addition, various global deficiencies, like an increase in inhibitory synaptic transmission, are proposed. Characteristics of these children include selective (inward) attention; underresponsiveness; stereotyped repetitive motor behavior; increased head size, weight, and height; various cognitive and communicative disorders; and also epilepsy. Therapy has emphasized risperidone, but some atypical antipsychotic medications have been helpful, as have robotic aids, massage, hyperbaric oxygen, and music. Nearly every conceivable problem that a child could have can be observed in these unfortunate children.