Autism: maternally derived antibodies specific for fetal brain proteins

Autism is a profound disorder of neurodevelopment with poorly understood biological origins. A potential role for maternal autoantibodies in the etiology of some cases of autism has been proposed in previous studies. To investigate this hypothesis, maternal plasma antibodies against human fetal and adult brain proteins were analyzed by western blot in 61 mothers of children with autistic disorder and 102 controls matched for maternal age and birth year (62 mothers of typically developing children (TD) and 40 mothers of children with non-ASD developmental delays (DD)). We observed reactivity to two protein bands at approximately 73 and 37kDa in plasma from 7 of 61 (11.5%) mothers of children with autism (AU) against fetal but not adult brain, which was not noted in either control group (TD; 0/62 p=0.0061 and DD; 0/40 p=0.0401). Further, the presence of reactivity to these two bands was associated with parent report of behavioral regression in AU children when compared to the TD (p=0.0019) and DD (0.0089) groups. Individual reactivity to the 37kDa band was observed significantly more often in the AU population compared with TD (p=0.0086) and DD (p=0.002) mothers, yielding a 5.69-fold odds ratio (95% confidence interval 2.09-15.51) associated with this band. The presence of these antibodies in the plasma of some mothers of children with autism, as well as the differential findings between mothers of children with early onset and regressive autism may suggest an association between the transfer of IgG autoantibodies during early neurodevelopment and the risk of developing of autism in some children.     

Autism-specific maternal autoantibodies recognize critical proteins in developing brain

Autism spectrum disorders (ASDs) are neurodevelopmental in origin, affecting an estimated 1 in 88 children in the United States. We previously described ASD-specific maternal autoantibodies that recognize fetal brain antigens. Herein, we demonstrate that lactate dehydrogenase A and B (LDH), cypin, stress-induced phosphoprotein 1 (STIP1), collapsin response mediator proteins 1 and 2 (CRMP1, CRMP2) and Y-box-binding protein to comprise the seven primary antigens of maternal autoantibody-related (MAR) autism. Exclusive reactivity to specific antigen combinations was noted in 23% of mothers of ASD children and only 1% of controls. ASD children from mothers with specific reactivity to LDH, STIP1 and CRMP1 and/or cypin (7% vs 0% in controls; P<0.0002; odds ratios of 24.2 (95% confidence interval: 1.45–405)) had elevated stereotypical behaviors compared with ASD children from mothers lacking these antibodies. We describe the first panel of clinically significant biomarkers with over 99% specificity for autism risk thereby advancing our understanding of the etiologic mechanisms and therapeutic possibilities for MAR autism.     

Antibodies against fetal brain in sera of mothers with autistic children

Serum antibodies in 100 mothers of children with autistic disorder (MCAD) were compared to 100 age-matched mothers with unaffected children (MUC) using as antigenic substrates human and rodent fetal and adult brain tissues, GFAP, and MBP. MCAD had significantly more individuals with Western immunoblot bands at 36 kDa in human fetal and rodent embryonic brain tissue. The density of bands was greater in fetal brain at 61 kDa. MCAD plus developmental regression had greater reactivity against human fetal brain at 36 and 39 kDa. Data support a possible complex association between genetic/metabolic/environmental factors and the placental transfer of maternal antibodies in autism.     

Behavioral Correlates of Maternal Antibody Status Among Children with Autism

Autism spectrum disorders (ASDs) affect approximately 1 in 110 children in the United States. This report profiles fetal-brain reactive autoantibodies of a large cohort of mothers of children with autism and controls, yielding significant associations between the presence of IgG reactivity to fetal brain proteins at 37 and 73 kDa and a childhood diagnosis of full autism (p = 0.0005), which also correlated with lower expressive language scores (p = 0.005). Additionally, we report on reactivity to proteins at 39 and 73 kDa, which correlated with the broader diagnosis of ASD (p = 0.0007) and increased irritability on the Aberrant Behavioral Checklist (p = 0.05). This study provides evidence of multiple patterns of reactivity to fetal brain proteins by maternal antibodies associated with ASD and specific childhood behavioral outcomes.     

Plasma serotonin in autism

Serotonin is necessary for normal fetal brain development. Administration of serotonin inhibitors to pregnant rats results in offspring with abnormal behaviors, brain morphology, and serotonin receptor numbers. Low maternal plasma serotonin may contribute to abnormal brain development in autism. In this study, plasma serotonin levels in autism mothers and control mothers of typically developing children were compared, and plasma serotonin levels in children with autism (n = 17) and their family members were measured. Plasma serotonin levels in autism mothers were significantly lower than in mothers of normal children (P = 0.002). Plasma serotonin levels correlated between autism mothers and their children, but differed between autistic children and their fathers (P = 0.028) and siblings (P = 0.063). Low maternal plasma serotonin may be a risk factor for autism through effects on fetal brain development.     

Brief Report: Antibodies Reacting to Brain Tissue in Basque Spanish Children with Autism Spectrum Disorder and Their Mothers

Previous investigations found that a subset of children with autism spectrum disorder (ASD) in California possessed plasma autoantibodies that reacted intensely with brain interneurons or other neural profiles. Moreover, for several cohorts of American women, maternal autoantibody reactivity to specific fetal brain proteins was highly specific to mothers of children with ASD. We sought to determine whether children and their mothers from a regionally specific cohort from the Basque Country of Spain demonstrated similar reactivity. Some children’s plasma reacted to interneurons, beaded axons or other neural profiles with no difference in the occurrence of these antibodies in children with or without ASD. Findings on the maternal antibodies confirmed previous research; plasma reactivity to fetal brain a combination of proteins at 37 and 73 kDa or 39 and 73 kDa was found exclusively in mothers of children with ASD.     

Detection of maternal antibodies in infantile autism

Maternal antibodies reactive with antigenic proteins expressed on the cell surface of paternal lymphocytes can be detected in couples with histories of more than one miscarriage or stillbirth. It is possible, but not proven, that these antibodies also react with tissues of the fetus and result in fetal death. Since many mothers of autistic children have a history of pregnancy disorder, antibodies were studied in 11 mothers of autistic children who were 6 years of age or younger. Six of the mothers had antibodies that reacted with lymphocytes of the autistic child. Five of these six mothers had a history of pregnancy disorder. Since antigens expressed on lymphocytes are found on cells of the central nervous system and, perhaps, other tissues of the developing embryo, it is suggested that aberrant maternal immunity may be associated with the development of some cases of infantile autism.     

Maternal neuronal antibodies associated with autism and a language disorder

Neurodevelopmental disorders could be caused by maternal antibodies or other serum factors. We detected serum antibodies binding to rodent Purkinje cells and other neurons in a mother of three children: the first normal, the second with autism, and the third with a severe specific language disorder. We injected the serum (0.5-1.0 ml/day) into pregnant mice during gestation and found altered exploration and motor coordination and changes in cerebellar magnetic resonance spectroscopy in the mouse offspring, comparing with offspring of mice injected with sera from mothers of healthy children. This evidence supports a role for maternal antibodies in some forms of neurodevelopmental disorder.     

Purkinje cell vulnerability and autism: a possible etiological connection

Autism is a neurological disorder of unknown etiology. The onset of the abnormal growth and development within the brain is also not known. Current thought by experts in autism is that the time of onset is prenatal, occurring prior to 30 weeks gestation. However, autism comprises a heterogeneous population in that parents report either that their child was abnormal from birth, or that their child was developmentally normal until sometime after birth, at which time the child began to regress or deteriorate. Anecdotal reports suggest that some children with autism have significant illness or clinical events prior to the development of autistic symptoms. Conceivably, these children may become autistic from neuronal cell death or brain damage sometime after birth as result of insult. To support this theory is that marked Purkinje cell loss, the most consistent finding in the autistic disorder, can result from insult. Evidence suggests that the Purkinje cell is selectively vulnerable. This article discusses a theory that the selective vulnerability of the Purkinje cell may play a role in the etiology of autism, and suggests that a future direction in autism research may be to investigate the possibility of neuronal cell loss from insult as a cause of autism. Results of a small pilot survey are also discussed.     

Familial clustering of autoimmune disorders and evaluation of medical risk factors in autism.

Autism is an age-dependent neurologic disorder that is often associated with autoimmune disorders in the patients' relatives. To evaluate the frequency of autoimmune disorders, as well as various prenatal and postnatal events in autism, we surveyed the families of 61 autistic patients and 46 healthy controls using questionnaires. The mean number of autoimmune disorders was greater in families with autism; 46% had two or more members with autoimmune disorders. As the number of family members with autoimmune disorders increased from one to three, the risk of autism was greater, with an odds ratio that increased from 1.9 to 5.5, respectively. In mothers and first-degree relatives of autistic children, there were more autoimmune disorders (16% and 21%) as compared to controls (2% and 4%), with odds ratios of 8.8 and 6.0, respectively. The most common autoimmune disorders in both groups were type 1 diabetes, adult rheumatoid arthritis, hypothyroidism, and systemic lupus erythematosus. Forty-six percent of the autism group reported having relatives with rheumatoid diseases, as compared to 26% of the controls. Prenatal maternal urinary tract, upper respiratory, and vaginal infections; asphyxia; prematurity, and seizures were more common in the autistic group, although the differences were not significant. Thirty-nine percent of the controls, but only 11% of the autistic, group, reported allergies. An increased number of autoimmune disorders suggests that in some families with autism, immune dysfunction could interact with various environmental factors to play a role in autism pathogenesis.     

Stereotypies and hyperactivity in rhesus monkeys exposed to IgG from mothers of children with autism

Autism together with Asperger syndrome and pervasive developmental disorder not otherwise specified form a spectrum of conditions (autism spectrum disorders or ASD) that is characterized by disturbances in social behavior, impaired communication and the presence of stereotyped behaviors or circumscribed interests. Recent estimates indicate a prevalence of ASD of 1 per 150 (Kuehn, 2007). The cause(s) of most cases of ASD are unknown but there is an emerging consensus that ASD have multiple etiologies. One proposed cause of ASD is exposure of the fetal brain to maternal autoantibodies during pregnancy [Dalton, P., Deacon, R., Blamire, A., Pike, M., McKinlay, I., Stein, J., Styles, P., Vincent, A., 2003. Maternal neuronal antibodies associated with autism and a language disorder. Ann. Neurol. 53, 533–537]. To provide evidence for this hypothesis, four rhesus monkeys were exposed prenatally to human IgG collected from mothers of multiple children diagnosed with ASD. Four control rhesus monkeys were exposed to human IgG collected from mothers of multiple typically developing children. Five additional monkeys were untreated controls. Monkeys were observed in a variety of behavioral paradigms involving unique social situations. Behaviors were scored by trained observers and overall activity was monitored with actimeters. Rhesus monkeys gestationally exposed to IgG class antibodies from mothers of children with ASD consistently demonstrated increased whole-body stereotypies across multiple testing paradigms. These monkeys were also hyperactive compared to controls. Treatment with IgG purified from mothers of typically developing children did not induce stereotypical or hyperactive behaviors. These findings support the potential for an autoimmune etiology in a subgroup of patients with neurodevelopmental disorders. This research raises the prospect of prenatal evaluation for neurodevelopmental risk factors and the potential for preventative therapeutics.     

Aberrant Cerebellar Neurotrophin-3 Expression Induced by Lipopolysaccharide Exposure During Brain Development

Autism is a developmental disorder affecting communication, social interaction, motor skills, and cerebellar structure and functions. Recent studies have indicated that maternal infection during brain development may be one of the risk factors for autism. We have previously demonstrated the abnormal overexpression of neurotrophin-3 (NT-3) in autistic cerebellum. To examine further the potential link between autism and maternal infection, and specifically NT-3 expression in the cerebellum, we used maternal lipopolysaccharide (LPS)-exposed rat model of infection. In group 1, pregnant female rats were exposed to 200 μg/kg body weight LPS delivered subcutaneously from gestational days (G) 10 to G15, and pups were exposed to LPS from postnatal days (P) 5 to P10, whereas in group 2, pups were exposed to the same dose of LPS from P5 to P10. There was no change in body mass of pups and mothers following LPS treatment. Cerebellar NT-3 levels were examined by enzyme-linked immunosorbent assay on P6, P12, and P21. We report here that cerebellar NT-3 levels were elevated in pups of both LPS groups as compared to the controls on P21. Our results suggest that altered neurotrophin levels may affect normal brain development and contribute to autistic pathology.     

Risk factors of autistic symptoms in children with ADHD

Autistic symptoms are frequently observed in children with attention-deficit/hyperactivity disorder (ADHD), but their etiology remains unclear. The main aim of this study was to describe risk factors for increased autistic symptoms in children with ADHD without an autism or autism-spectrum diagnosis. Comorbid psychiatric disorders, developmental delay, current medication, prenatal biological and postnatal psychosocial risk factors as well as parental autistic traits were assessed in 205 children with ADHD. Linear regression models identified maternal autistic traits, current familial risk factors and hyperactive symptoms as predictors of autistic symptoms in children with ADHD. Findings are indicative of possible genetic as well as environmental risk factors mediating autistic symptoms in children with ADHD. An additional validity analysis by ROC, area under the curve (AUC), suggested a cut-off of 11 to differentiate between ADHD and high-functioning ASD by the Social Communication Questionnaire (SCQ).     

Maternal autoantibodies are associated with abnormal brain enlargement in a subgroup of children with autism spectrum disorder

Autism spectrum disorder (ASD) is very heterogeneous and multiple subtypes and etiologies likely exist. The maternal immune system has been implicated in the pathogenesis of some forms of ASD. Previous studies have identified the presence of specific maternal IgG autoantibodies with reactivity to fetal brain proteins at 37 and 73 kDa in up to 12% of mothers of children with ASD. The current study evaluates the presence of these autoantibodies in an independent cohort of mothers of 181 preschool-aged male children (131 ASD, 50 typically developing (TD) controls). We also investigated whether ASD children born to mothers with these autism-specific maternal IgG autoantibodies exhibit a distinct neural phenotype by evaluating total brain volume using structural magnetic resonance imaging (MRI). Of the 131 ASD children, 10 (7.6%) were born to mothers with the 37/73 kDa IgG autoantibodies (ASD-IgG). The mothers of the remaining ASD children and all TD controls were negative for these paired autoantibodies. While both ASD groups exhibited abnormal brain enlargement that is commonly observed in this age range, the ASD-IgG group exhibited a more extreme 12.1% abnormal brain enlargement relative to the TD controls. In contrast, the remaining ASD children exhibited a smaller 4.4% abnormal brain enlargement relative to TD controls. Lobar and tissue type analyses revealed that the frontal lobe is selectively enlarged in the ASD-IgG group and that both gray and white matter are similarly affected. These results suggest that maternal autoantibodies associated with autism spectrum disorder may impact brain development leading to abnormal enlargement.     

Early pharmacological treatment of autism: a rationale for developmental treatment.

Autism is a dynamic neurodevelopmental syndrome in which disabilities emerge during the first three postnatal years and continue to evolve with ongoing development. We briefly review research in autism describing subtle changes in molecules important in brain development and neurotransmission, in morphology of specific neurons, brain connections, and in brain size. We then provide a general schema of how these processes may interact with particular emphasis on neurotransmission. In this context, we present a rationale for utilizing pharmacologic treatments aimed at modifying key neurodevelopmental processes in young children with autism. Early treatment with selective serotonin reuptake inhibitors (SSRIs) is presented as a model for pharmacologic interventions because there is evidence in autistic children for reduced brain serotonin synthesis during periods of peak synaptogenesis; serotonin is known to enhance synapse refinement; and exploratory studies with these agents in autistic children exist. Additional hypothetical developmental interventions and relevant published clinical data are described. Finally, we discuss the importance of exploring early pharmacologic interventions within multiple experimental settings in order to develop effective treatments as quickly as possible while minimizing risks.     

Autoantibodies to cerebellum in children with autism associate with behavior

Autism is a heterogeneous disorder with a poorly understood biological basis. Some children with autism harbor plasma autoantibodies that target brain proteins. Similarly, some mothers of children with autism produce antibodies specific to autism that target pairs of fetal brain proteins at 37/73 and 39/73 kDa. We explored the relationship between the presence of brain-specific autoantibodies and several behavioral characteristics of autism in 277 children with an autism spectrum disorder and 189 typically developing age-matched controls. Further, we used maternal autoantibody data to investigate potential familial relationships for the production of brain-directed autoantibodies. We demonstrated by Western blot that autoantibodies specific for a 45 kDa cerebellar protein in children were associated with a diagnosis of autism (p = 0.017) while autoantibodies directed towards a 62 kDa protein were associated with the broader diagnosis of autism spectrum disorder (ASD) (p = 0.043). Children with such autoantibodies had lower adaptive (p = 0.0008) and cognitive function (p = 0.005), as well as increased aberrant behaviors (p < 0.05) compared to children without these antibodies. No correlation was noted for those mothers with the most specific pattern of anti-fetal brain autoantibodies and children with the autoantibodies to either the 45 or 62 kDa bands. Collectively, these data suggest that antibodies towards brain proteins in children are associated with lower adaptive and cognitive function as well as core behaviors associated with autism. It is unclear whether these antibodies have direct pathologic significance, or if they are merely a response to previous injury. Future studies are needed to determine the identities of the protein targets and explore their significance in autism.     

Autoantibody repertoires to brain tissue in autism nuclear families

The hypothesis of an immune dysfunction in autism spectrum disorders has previously been put forward without, however, compelling evidence of a direct relation to its etiology or pathogenesis. To further understand if autoimmunity could play a significant role in autism, we analyzed autoantibody repertoires to brain tissue extract in the plasma of 171 autism children, their parents, and 54 controls, by quantitative immunoblotting. Multiparametric analysis revealed significant differences between patients and controls, and showed that one single reactivity in Section 32 of the blot had the most power to discriminate between these samples. Family correlation coefficients and heritability estimates did not provide any evidence that this reactivity was genetically determined. While the molecular weight of the target protein suggested that it might be an isoform of Myelin Basic Protein (MBP), inhibition assays with human MBP argued against this hypothesis. The study evidences the widespread occurrence of autoreactivities to brain tissue in autism patients, which may represent the immune system's neuroprotective response to a previous brain injury occurred during neurodevelopment. The molecular identification of the target protein in Section 32 will contribute to the understanding of the role of immune responses against brain antigens in autistic patients.     

Obstetric complications in individuals diagnosed with autism and in healthy controls

The aim of the present study was to investigate birth complications in Israeli autistic probands. We interviewed 206 mothers of autistic probands and 152 healthy control mothers with a structured tool encompassing prenatal, perinatal, and neonatal complications. Analysis of obstetric suboptimality, derived by summing all positive items of each of the 3 categories and dividing them by the number of patients analyzed, revealed no prenatal between-group difference. The controls had a somewhat elevated perinatal suboptimality score, whereas the autistic probands had a significantly greater neonatal suboptimality score. These differences in obstetric suboptimality were retained after controlling for the demographic parameters found different between the 2 groups (sex of participants and mothers' years of schooling). Our findings suggest that the presence of nonspecific neonatal factors, rather than the specific influence of individual severe insults, may account for the elevated neonatal suboptimality found in probands diagnosed with autism compared with healthy controls.     

Antibrain antibodies in children with autism and their unaffected siblings

Serum autoantibodies to human brain, identified by ELISA and Western immunoblotting, were evaluated in 29 children with autism spectrum disorder (22 with autistic disorder), 9 non-autistic siblings and 13 controls. More autistic subjects than controls had bands at 100 kDa in caudate, putamen and prefrontal cortex (p<0.01) as well as larger peak heights of bands at 73 kDa in the cerebellum and cingulate gyrus. Both autistic disorder subjects and their matched non-autistic siblings had denser bands (peak height and/or area under the curve) at 73 kDa in the cerebellum and cingulate gyrus than did controls (p<0.01). Results suggest that children with autistic disorder and their siblings exhibit differences compared to controls in autoimmune reactivity to specific epitopes located in distinct brain regions.     

Higher autism in children of women with psychiatric diagnoses

BackgroundTo determine the extent to which medical record history of maternal psychiatric diagnoses was associated with offspring autism risk in a large, socio-demographically diverse birth cohort.MethodThis retrospective cohort study linked hospital discharge records for 8,951,763 California singleton births occurring 1/1/91-12/31/08 from the Office of Statewide Health Planning and Development with diagnostic and service records from the Department of Developmental Services. Medical records documenting maternal mood and anxiety disorders and schizophrenia ICD-9-CM codes were identified, and 42,423 children were categorized with a DSM-IV diagnosis of ‘autistic disorder’. Log-linear Poisson models explored the relationships between maternal psychiatric disorders and autism, adjusting for maternal education, race, country of birth, and parental age.ResultsRates of maternal psychiatric diagnoses were lower than expected for the population, reflecting under-recognition and under-reporting by inpatient clinicians. In adjusted analyses, mothers diagnosed with one individual psychiatric condition were 1.2–2.8 times more likely to have a child who developed autism. Mothers diagnosed with any one or more psychiatric condition were twice as likely to have a child with autism compared with unaffected or unreported women (RR = 1.97; 95% CI 1.83–2.12).ConclusionsWomen with a documented inpatient medical record history of psychiatric diagnosis were nearly twice as likely as women without such diagnoses to have a child later diagnosed with autism. These findings highlight the need for routine prenatal screening for psychiatric conditions, as well as enhanced neurobehavioral assessment of children born to these mothers to detect early autism signs and optimize intervention timeliness.