Autoantibodies to cerebellum in children with autism associate with behavior

https://doi.org/10.1016/j.bbi.2010.11.017Get rights and content

Abstract

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.

Research highlights

► Plasma autoantibodies for 45 kDa cerebellar protein associate with an autism diagnosis. ► Plasma autoantibodies for 62 kDa protein associate with broader diagnosis of ASD. ► Children with autoantibodies had worse behavioral scores than children without them. ► Few familial associations found for brain-targeted antibodies in children and mothers. ► Antibodies may be markers for specific behavioral characteristics of autism.

Introduction

Autism spectrum disorders are a group of psychological conditions that manifest in early childhood. These disorders are characterized by widespread abnormalities of social interactions and communication, as well as restricted interests and repetitive behavior (American Psychiatric Association, 1994, Lord et al., 2000a, World Heath Organization, 2006). The autism phenotype is heterogeneous with regard to behavioral severity and disease onset (Meilleur and Fombonne, 2009, Micali et al., 2004, Ozonoff et al., 2010, Stefanatos, 2008). Autism spectrum disorders are clinically defined, and current diagnosis is based entirely on behavioral testing and analysis of medical and developmental history (Le Couteur et al., 2008, Lord et al., 2000b, Lord et al., 1994). The pathology and etiology of these disorders remain unclear; though emerging evidence suggests that genetic, neurological, environmental, and immune factors are likely involved (Pardo and Eberhart, 2007).

The neurobiology of autism spectrum disorders has been explored through various imaging techniques and examination of post-mortem samples. Data suggest that abnormal brain growth, altered neuronal migration and connectivity, and/or changes in minicolumnar organization may be involved (Pardo and Eberhart, 2007). Subtle differences have been reported in brain regions including the cerebral cortex, limbic structures, and cerebellum (Pardo and Eberhart, 2007). Overall, the neurological basis of autism spectrum disorders remains poorly understood, largely due to difficulties in obtaining quality post-mortem samples and a lack of information on early brain development. Further, the factors that cause neurological abnormalities are largely undefined.

Immune dysregulation has been noted among individuals with an autism spectrum disorder and their family members (Ashwood et al., 2006). This includes inflammation in the central nervous system (CNS) and gastrointestinal tract (Ashwood et al., 2004, Vargas et al., 2005), as well as differences in system-wide humoral and cellular immunity (Ashwood et al., 2006, Pardo et al., 2005). There are several reports of altered IgG and cytokine levels in subjects with an autism spectrum disorder compared to typically developing children (Ashwood et al., 2008a, Ashwood et al., 2008b, Enstrom et al., 2009a, Grigorenko et al., 2008, Heuer et al., 2008). Further, variations in immune parameters often correlate with behavioral severity (Ashwood et al., 2008a, Ashwood et al., 2008b, Enstrom et al., 2009a, Enstrom et al., 2010, Grigorenko et al., 2008, Heuer et al., 2008, Onore et al., 2009).

Autoimmune and allergy-associated disorders also appear more frequently in individuals with an autism spectrum disorder and their families compared to control populations (Ashwood and Van de Water, 2004, Ashwood et al., 2006, Cabanlit et al., 2007, Croen et al., 2005, Mostafa and Kitchener, 2009, Silva et al., 2004). Several studies have noted the presence of autoantibodies in peripheral blood that react with components of the central nervous system (CNS) (Enstrom et al., 2009b). The mechanistic role of these antibodies in autism spectrum disorders is not clear, and it remains to be determined whether they are pathogenic or if they are produced as a secondary result of neuronal insult. Similar phenomena have been described in other neurological disorders including Tourette’s syndrome, Syndenham’s chorea and obsessive compulsive disorder (Church et al., 2002, Swedo et al., 1998). CNS targets reported for autism spectrum disorders include the thalamus, hypothalamus, caudate nucleus, cerebral cortex, putamen, and cerebellum (Cabanlit et al., 2007, Connolly et al., 1999, Silva et al., 2004, Singer et al., 2006, Singh and Rivas, 2004, Vojdani et al., 2004, Wills et al., 2009). Research in our laboratory suggests that the cerebellum is the most consistent target of these antibodies (Cabanlit et al., 2007, Wills et al., 2007), and changes in cerebellum function can result in various behavioral and cognitive issues commonly observed in autism spectrum disorders (Gillig and Sanders, 2010, Steinlin, 2008). However, it is unknown if such autoantibodies to brain proteins coincide with specific behavioral features of the disorder. Although their exact involvement in autism is unknown, these antibodies provide valuable insight into biological mechanisms potentially associated with this behaviorally defined disorder.

In addition to the findings of brain-directed antibodies in children with autism, a subset of mothers of children with autism have been shown to harbor plasma IgG that targets fetal brain proteins (Braunschweig et al., 2008, Croen et al., 2008, Singer et al., 2008, Zimmerman et al., 2007). During pregnancy, maternal IgG is passed across the placenta into fetal circulation (Simister, 2003). Animals exposed to these fetal brain-directed autoantibodies during gestation demonstrate altered behavior, which suggests that maternal antibodies may be of pathologic significance (Martin et al., 2008, Singer et al., 2009). However, it remains unclear whether there is a relationship between the production of fetal brain-directed autoantibodies in mothers of children with autism and the production of autoantibodies specific for mature brain in their children.

The goals of the current study were twofold: (1) to further characterize the occurrence of autoantibodies to mature cerebellum in a large group of children with an autism spectrum disorder, and to determine whether the presence of these autoantibodies relates to specific behavioral outcomes, and (2) to ascertain if there is a familial association for the presence of these autoantibodies in children and the presence of fetal brain-directed antibodies in their respective mothers. The occurrence of cerebellum-specific autoantibodies in children was analyzed in plasma samples from a large, well-characterized, and phenotypically diverse population of subjects with autism (AU), the broader diagnosis of autism spectrum disorder (ASD), and typically developing (TD) age-matched control children. In addition, mothers of the subjects included in the current study were screened for fetal brain-specific autoantibodies to determine possible familial relationships for brain-specific antibodies.

Section snippets

Subjects

The current study involved 466 children and 439 mothers enrolled through the CHARGE (Childhood Autism Risks from Genetics and the Environment) study at the U.C. Davis M.I.N.D. (Medical Investigations of Neurodevelopmental Disorders) Institute at the University of California, Davis, which has previously been described in detail (Hertz-Picciotto et al., 2006). The CHARGE study is an ongoing population-based case-control study including children with autism (AU) or the broader diagnosis of autism

Cerebellum-targeted autoantibodies in children

Plasma from children with AU, ASD, and TD controls was screened for autoantibodies towards proteins isolated from adult Rhesus macaque cerebellum by Western blot. Two immunoreactive targets within the cerebellum appeared significantly more often among AU and ASD groups compared to controls (Table 2, Fig. 1, Fig. 2, Fig. 3). Children with AU were found to have a significantly higher incidence of autoantibodies directed towards a 45 kDa cerebellum protein compared to the TD group (9.7% in AU, 3.6%

Discussion

This study had two primary goals: (1) to further characterize the occurrence of autoantibodies to cerebellum in children with autism spectrum disorders with respect to behavioral outcome, and (2) to ascertain if an association exists between the presence of brain-directed autoantibodies in children and the presence of brain-directed antibodies in their respective mothers. Autoantibody profiles differed between children with autism (AU), the broader phenotype of autism spectrum disorder (ASD),

Conflict of interest statement

This study was funded by NIEHS P01 ES11269; RO1 ES015359; U.S. EPA STAR program Grant R829388.

References (64)

  • C.M. Morris et al.

    Childhood serum anti-fetal brain antibodies do not predict autism

    Pediatr. Neurol.

    (2009)
  • G.A. Mostafa et al.

    Serum anti-nuclear antibodies as a marker of autoimmunity in Egyptian autistic children

    Pediatr. Neurol.

    (2009)
  • C. Onore et al.

    Decreased cellular IL-23 but not IL-17 production in children with autism spectrum disorders

    J. Neuroimmunol.

    (2009)
  • S.C. Silva et al.

    Autoantibody repertoires to brain tissue in autism nuclear families

    J. Neuroimmunol.

    (2004)
  • N.E. Simister

    Placental transport of immunoglobulin G

    Vaccine

    (2003)
  • H.S. Singer et al.

    Antibrain antibodies in children with autism and their unaffected siblings

    J. Neuroimmunol.

    (2006)
  • H.S. Singer et al.

    Antibodies against fetal brain in sera of mothers with autistic children

    J. Neuroimmunol.

    (2008)
  • H.S. Singer et al.

    Prenatal exposure to antibodies from mothers of children with autism produces neurobehavioral alterations: a pregnant dam mouse model

    J. Neuroimmunol.

    (2009)
  • V.K. Singh et al.

    Prevalence of serum antibodies to caudate nucleus in autistic children

    Neurosci. Lett.

    (2004)
  • S. Wills et al.

    Detection of autoantibodies to neural cells of the cerebellum in the plasma of subjects with autism spectrum disorders

    Brain Behav. Immun.

    (2009)
  • A.W. Zimmerman et al.

    Maternal antibrain antibodies in autism

    Brain Behav. Immun.

    (2007)
  • S.N. Aman MG

    Aberrant Behavior Checklist-Community. Supplementary Manual

    (1994)
  • Diagnostic and Statistical Manual of Mental Disorders

    (1994)
  • P. Ashwood et al.

    Spontaneous mucosal lymphocyte cytokine profiles in children with autism and gastrointestinal symptoms: mucosal immune activation and reduced counter regulatory interleukin-10

    J. Clin. Immunol.

    (2004)
  • P. Ashwood et al.

    The immune response in autism: a new frontier for autism research

    J. Leukoc. Biol.

    (2006)
  • Ashwood, P., Enstrom, A., Krakowiak, P., Hertz-Picciotto, I., Hansen, R.L., Croen, L.A., Ozonoff, S., Pessah, I.N., de...
  • P. Ashwood et al.

    Brief report: plasma leptin levels are elevated in autism: association with early onset phenotype?

    J. Autism Dev. Disord.

    (2008)
  • A. Bailey et al.

    A clinicopathological study of autism

    Brain

    (1998)
  • Braunschweig, D., Duncanson, P., Boyce, R., Hansen, R., Ashwood, P., Pessah, I., Hertz-Picciotto, I., Van de Water, J.,...
  • M. Cabanlit et al.

    Brain-specific autoantibodies in the plasma of subjects with autistic spectrum disorder

    Ann. N. Y. Acad. Sci.

    (2007)
  • A.J. Church et al.

    Anti-basal ganglia antibodies in acute and persistent Sydenham’s chorea

    Neurology

    (2002)
  • L.A. Croen et al.

    Maternal autoimmune diseases, asthma and allergies, and childhood autism spectrum disorders: a case–control study

    Arch. Pediatr. Adolesc. Med.

    (2005)
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