Christina M. Morris

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

A pregnant mouse model was used to compare the effect of IgG, administered E13-E18, from mothers of children with autistic disorder (MCAD), to controls (simple- and IgG-) on behavioral testing in offspring. Mice, exposed in-utero to MCAD-IgG, as adolescents, were more active during the first ten minutes of central field novelty testing and, as adults, displayed anxiety-like behavior on a component of the elevated plus maze and had a greater magnitude of startle following acoustic stimulation. On a social interaction paradigm, adult mice had alterations of sociability. Pilot studies of immune markers in MCAD IgG-exposed embryonic brains suggest evidence of cytokine and glial activation. These studies demonstrate that the transplacental passage of IgG from MCAD is capable of inducing long-term behavioral consequences.

Serial Immune Markers Do Not Correlate With Clinical Exacerbations in Pediatric Autoimmune Neuropsychiatric Disorders Associated With Streptococcal Infections

OBJECTIVE. Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections is hypothesized to be a poststreptococcal autoimmune disorder. If clinical exacerbations are triggered by a streptococcal infection that activates cross-reacting antibodies against neuronal tissue or alters the production of cytokines, then a longitudinal analysis would be expected to identify a correlation between clinical symptoms and a change in autoimmune markers. PATIENTS AND METHODS. Serial serum samples were available on 12 children with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections participating in a prospective blinded study: 2 samples before an exacerbation point, 1 during the clinical exacerbation, and 2 after the exacerbation. Six subjects had a well-defined clinical exacerbation in association with a documented streptococcal infection, and 6 had a clinical exacerbation without an associated streptococcal infection. All of the serum samples were assayed for antibodies against human postmortem caudate, putamen, and prefrontal cortex; commercially prepared antigens; and complex sugars. Cytokines were measured by 2 different methodologies. RESULTS. No correlation was identified between clinical exacerbations and autoimmune markers, including: enzyme-linked immunosorbent assay measures of antineuronal antibodies; Western immunoblotting with emphasis on brain region proteins located at 40, 45, and 60 kDa or their corresponding identified antigens; competitive inhibition enzyme-linked immunosorbent assay to evaluate lysoganglioside GM1 antibodies; and measures of inflammatory cytokines. No differences were identified between individuals with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections with or without exacerbations triggered by streptococcal infections. CONCLUSIONS. The failure of immune markers to correlate with clinical exacerbations in children with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections raises serious concerns about the viability of autoimmunity as a pathophysiological mechanism in this disorder.

Dopaminergic polymorphisms in Tourette syndrome: Association with the DAT gene (SLC6A3)

Tourette syndrome (TS) is a chronic neuropsychiatric disorder characterized by involuntary motor and phonic tics. The pattern of inheritance and associated genetic abnormality has yet to be fully characterized. A dopaminergic abnormality in this disorder is supported by response to specific therapies, nuclear imaging, and postmortem studies. In this protocol, dopaminergic polymorphisms were examined for associations with TS and attention‐deficit hyperactivity disorder (ADHD). Polymorphisms investigated included the dopamine transporter (DAT1 DdeI and DAT1 VNTR), dopamine receptor (D4 Upstream Repeat and D4 VNTR), dopamine converting enzyme (dopamine β‐hydroxylase), and the acid phosphatase locus 1 (ACP1) gene. DNA was obtained from 266 TS individuals ± ADHD and 236 controls that were ethnicity‐matched. A significant association, using a genotype‐based association analysis, was identified for the TS‐total and TS‐only versus control groups for the DAT1 DdeI polymorphism (AG vs. AA, P = 0.004 and P = 0.01, respectively). Population structure, estimated by the genotyping of 27 informative SNP markers, identified 3 subgroups. A statistical re‐evaluation of the DAT1 DdeI polymorphism following population stratification confirmed the association for the TS‐total and TS‐only groups, but the degree of significance was reduced (P = 0.017 and P = 0.016, respectively). This study has identified a significant association between the presence of TS and a DAT polymorphism. Since abnormalities of the dopamine transporter have been hypothesized in the pathophysiology of TS, it is possible that this could be a functional allele associated with clinical expression.

Double-Blind, Crossover Study of Clonidine and Levetiracetam in Tourette Syndrome

We compared the efficacy of clonidine and levetiracetam for treating tics in Tourette syndrome. Twelve subjects were enrolled; 10 (ages 8-27 years) with moderate to moderately severe tics completed a 15-week randomized, double-blind, flexible-dose crossover protocol. Initial medication doses were clonidine (0.05 mg, twice daily) or levetiracetam (10 mg/kg/day, divided twice daily). Doses were adjusted weekly, based on telephone assessment. The primary outcome measure was baseline-to-posttreatment (6-week) change in Total Tic Score of the Yale Global Tic Severity Scale. Secondary outcome measures included total Yale Global Tic Severity Scale and Clinical Global Impression scores and behavioral measures. The mean Total Tic Score improved significantly from baseline to posttreatment with clonidine (25.2 versus 21.8) compared with levetiracetam (22.7 versus 23.6) (P = 0.013). The mean total Yale Global Tic Severity Scale and Clinical Global Impression score did not change. For levetiracetam, no changes occurred in any scales. No significant change occurred in any secondary behavioral outcome measures for either group. The most commonly reported side effects were, for clonidine, sedation (n = 5), and for levetiracetam, irritability (n = 4). Treatment with clonidine, but not levetiracetam, resulted in a small reduction in Total Tic Score, with an effect size of 0.57.

Serum autoantibodies measured by immunofluorescence confirm a failure to differentiate PANDAS and Tourette syndrome from controls

PANDAS and some cases of Tourette syndrome (TS) have been proposed to be post-streptococcal movement disorders in which antibodies produced against group A beta-hemolytic streptococcus cross react against brain epitopes. Attempts to identify disease specific anti-striatal antibodies in the serum of affected patients have focused on the use of Western immunoblotting and ELISA methodologies. In this study, immunohistochemical techniques were used to identify serum anti-striatal antibody reactivity. In positive samples, double staining with anti-GFAP (glial) and anti-MAP2 (neuronal) was used to establish localization of the immunofluorescence. No significant differences in immunofluorescence or localization were identified in patients with PANDAS (n=30) and TS (n=30) as compared to controls (n=30). IF reactivity did not correlate with tic severity or elevated titers of antistreptococcal antibodies. Further comparisons showed no correlation between autoreactivity determined by immunofluorescence and the presence of previously measured immunoblot reactivity against human caudate or putative antigens (pyruvate kinase M1 and aldolase C). These results confirm an inability to distinguish patient populations by antibody measurements and raise further concerns about the presence of an autoimmune mechanism in PANDAS and TS.

Glutamatergic modulatory therapy for Tourette syndrome

Tourette syndrome (TS) is a neuropsychiatric disorder characterized by the presence of chronic, fluctuating motor and vocal (phonic) tics. The disorder is commonly associated with a variety of comorbidities including obsessive-compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), school problems, anxiety, and depression. Therapeutically, if tics are causing psychosocial or physical problems, symptomatic medications are often prescribed, typically alpha-adrenergic agonists or dopamine antagonists. Recognizing that therapy is often ineffective and frequently associated with unacceptable side-effects, there is an ongoing effort to identify new tic-suppressing therapies. Several lines of evidence are presented that support the use of glutamate modulators in TS including glutamates major role in cortico-striatal-thalamo-cortical circuits (CSTC), the recognized extensive interaction between glutamate and dopamine systems, results of familial genetic studies, and data from neurochemical analyses of postmortem brain samples. Since insufficient data is available to determine whether TS is definitively associated with a hyper- or hypo-glutamatergic state, potential treatment options using either glutamate antagonists or agonists are reviewed. Data from studies using these agents in the treatment of OCD are presented. If validated, modulation of the glutamate system could provide a valuable new pharmacological approach in the treatment of tics associated with Tourette syndrome.

Antineuronal antibodies in OCD: comparisons in children with OCD-only, OCD+chronic tics and OCD+PANDAS.

Autoimmunity associated with a streptococcal infection has been proposed as a pathogenic mechanism for obsessive-compulsive disorder (OCD) in children. Antibrain antibody profiles were compared in children with OCD-only (n = 13; 14.1 +/- 3.1 years), OCD+PANDAS (n = 20; 11.3 +/- 1.5 years), OCD+Chronic Tic Disorder (n = 23; 13.4 +/- 3.5 years), and controls (n = 29; 12.4 +/- 2.4 years) using ELISA (orbitofrontal (OFC) and dorsolateral prefrontal cortex (DLPFC), caudate (CD), cingulate gyrus (CG)), immunoblotting (four regions plus putative antigens), and immunohistochemistry. ELISA and immunohistochemistry showed no differences among groups. Immunoblot showed that a greater percentage of individuals in the OCD+PANDAS cohort had reactive bands at 27 kDa (CD, CG, DLPFC), 36 kDa (CD), and 100 kDa (CD, OFC) and increased peak height at 67 kDa (all regions). Immunoblotting studies using the putative antigens (pyruvate kinase M1, aldolase C, alpha- and gamma-enolase) did not differ among groups. ASO titers were similar in all groups and did not correlate with immunoassays. It remains controversial whether childhood OCD is associated with autoimmune mechanisms.

Childhood Serum Anti-Fetal Brain Antibodies Do Not Predict Autism

Autoimmune hypotheses for autism include in utero transplacental exposure to maternal antibodies and acquired postnatal insults. Previous work demonstrated that some mothers of children with autistic disorder have specific antibodies against human fetal brain that differentiate them from mothers with typical children. In the present study, Western immunoblotting was used to determine whether children with autistic spectrum disorders (n = 29) have serum reactivity against human fetal brain that differs from that of controls (n = 14). There was no significant difference in reactivity, corrected for serum immunoglobulin G content and brain actin content and with special attention to reactive bands at 36, 39, 61, and 73 kDa, between autistic children and normal control subjects. Thus, in contrast to mothers, antibody reactivity against human fetal brain as measured in children ages 3-12 years does not appear to be a useful biomarker for autism.

Maternal Antibodies and the Placental–Fetal IgG Transfer Theory

We hypothesize that maternal autoimmunity is a contributing factor to etiology in up to 40% of pregnancies that lead to autism. More specifically, we propose that the transplacental transfer of maternal antibodies to the fetus alters fetal brain development, and, on a background of genetic susceptibility, ultimately leads to the postnatal emergence of autism. Circumstantial evidence for this hypothesis includes human studies showing that maternal autoimmune disorders can adversely affect fetal brain development, as well as studies of human leukocyte antigens (HLA). To date, two groups of investigators have identified differential patterns of specific antibodies directed to human fetal brain in sera from mothers of children with autistic disorder (MCAD) as compared with mothers of unaffected children. In both studies, specific maternal antibodies correlated with the presence of developmental regression in offspring. Lastly, the pregnant dam mouse model has shown that MCAD IgG can cross the placenta, enter embryonic brain, induce an immune response, and cause behavioral changes. In this chapter, we review circumstantial and direct evidence for, and future requirements necessary to confirm, the placental–fetal IgG transfer theory.