An animal model of Tourette's syndrome

RatDEGdb: a knowledge base of differentially expressed genes in the rat as a model object in biomedical research

The animal models used in biomedical research cover virtually every human disease. RatDEGdb, a knowledge base of the differentially expressed genes (DEGs) of the rat as a model object in biomedical research is a collection of published data on gene expression in rat strains simulating arterial hypertension, age-related diseases, psychopathological conditions and other human afflictions. The current release contains information on 25,101 DEGs representing 14,320 unique rat genes that change transcription levels in 21 tissues of 10 genetic rat strains used as models of 11 human diseases based on 45 original scientific papers. RatDEGdb is novel in that, unlike any other biomedical database, it offers the manually curated annotations of DEGs in model rats with the use of independent clinical data on equal changes in the expression of homologous genes revealed in people with pathologies. The rat DEGs put in RatDEGdb were annotated with equal changes in the expression of their human homologs in affected people. In its current release, RatDEGdb contains 94,873 such annotations for 321 human genes in 836 diseases based on 959 original scientific papers found in the current PubMed. RatDEGdb may be interesting first of all to human geneticists, molecular biologists, clinical physicians, genetic advisors as well as experts in biopharmaceutics, bioinformatics and personalized genomics. RatDEGdb is publicly available at https://www.sysbio.ru/RatDEGdb.

Striatal Syntaxin 1A Is Associated with Development of Tourette Syndrome in an Iminodipropionitrile-Induced Animal Model

Tourette syndrome (TS) is a neurodevelopmental movement disorder characterized by multiple motor and vocal tics. In this study, we used a TS rat model induced by 3,3′-iminodipropionitrile (IDPN) and aimed to investigate the expression change of Syntaxin 1A (STX1A). Rats in the control group received intraperitoneal injection of normal saline, and TS rats were injected with IDPN (150 mg/kg/day). After 7 days of treatment, the stereotypic behaviors were assessed. Next, rats were sacrificed; brains were removed for RNA extraction and Western blotting analysis and fixed in 4% paraformaldehyde for immunofluorescence analysis. After 7 days of IDPN administration, stereotypic behaviors were successfully induced. The IDPN group exhibited more counts in biting, putting forepaws around mouth, licking, head twitching, shaking claws, body raising, and episodic utterance. The striatal STX1A mRNA, protein, and STX1A expression in striatal dopaminergic neurons were investigated. As expected, the total STX1A mRNA and protein levels were decreased in the TS model rats. In the striatal dopaminergic neurons, the IDPN group showed a slightly decreased STX1A/TH double positive area, but no statistical significance was found. Additionally, we assessed the expression of some genes closely related to STX1A, such as SNAP25, SY, and gephyrin, and no differences were found between the two groups. Together, reduced STX1A expression is associated with IDPN-induced TS development. Our findings suggested that decreased striatal STX1A expression is associated with the development of TS in the IDPN-induced rat model.

Pediatric neuropsychiatric syndromes associated with infection and microbiome alterations: clinical findings, possible role of the mucosal epithelium, and strategies for the development of new animal models

INTRODUCTION

: Subsets of pediatric obsessive-compulsive disorder (OCD) and autism spectrum disorder (ASD) respectively have been associated with respiratory tract infections and alterations in the intestinal microbiome. Pediatric Acute-onset Neuropsychiatric Syndromes (PANS) refers to the sudden onset of neuropsychiatric symptoms that are triggered by several different infectious and non-infectious factors. Clinical studies and animal modeling are consistent with the proposal that inflammation plays an important etiological role in PANS, as well as in ASD associated with gut dysbiosis.

AREAS COVERED

The authors provide an overview of clinical studies of PANS and ASD associated with gastrointestinal symptoms, as well as the current strategies for studying these syndromes in rodent models. Finally, the authors highlight similarities between these syndromes that may provide clues to common etiological mechanisms.

EXPERT OPINION

Although data from existing animal models are consistent with an important role for anti-neuronal antibodies in PANS triggered by GAS infection, we lack models for identifying pathophysiological mechanisms of PANS associated with other infectious and non-infectious triggers. The authors propose a strategy for developing such models that incorporates known vulnerability and triggering factors for PANS into the modeling process. This novel strategy should expand our understanding of the pathophysiology of PANS, as well as facilitate the development of new pharmacological treatments for PANS and related syndromes.

Induction of Ticlike Involuntary Movements in Rats by Striatotomy and Subsequent Neurochemical Sensitization

OBJECTIVE

It has been proposed that Tourette syndrome is associated with dysfunction in widespread cortical areas and globus pallidus externus hyperactivity secondary to dopaminergic hyperactivity and serotonergic/dynorphinergic hypoactivity. The main objective of this study was to test this hypothesis by developing an animal model of Tourette syndrome via striatotomy, followed by administration of drugs that mimic the neurotransmitter environment, so as to induce globus pallidus externus hyperactivity.

METHODS

Rats were assigned to 3 groups: stereotactic striatotomy (STT) and striatal sham -lesion (SHAM) groups, treated with anterior and posterior striatum procedures in both hemispheres, and a group of nonoperated animals (NAIVE). Postoperatively, all rodents were blindly administered 3 drug protocols: levodopa/benserazide; levodopa/benserazide/ergotamine/naloxone (MIX); and saline. The animals were filmed at the peak action of these drugs. The videos were evaluated by a single blinded researcher.

RESULTS

Six types of involuntary movements (IMs) were observed: cephalic, trunk jerks, oromandibular, forepaw jerks, dystonic, and locomotive. The number of animals with IM and the mean number of IM after both levodopa/benserazide and MIX was significantly higher in the STT compared with the SHAM and NAIVE groups. In the SHAM and NAIVE, MIX was superior to levodopa/benserazide in the induction of IM. In the STT, MIX was superior to levodopa/benserazide in the induction of trunk jerks. Appendicular IM were more common after posterior than after anterior striatotomy.

CONCLUSIONS

These results show that striatotomy, followed by administration of levodopa/benserazide alone or associated with ergotamine and naloxone, is efficacious in inducing IM, supporting the hypothesis that led to this study.

Immunity and Gilles de la Tourette syndrome: A systematic review and meta-analysis of evidence for immune implications in Tourette syndrome

BACKGROUND AND PURPOSE

The neurobiology of Gilles de la Tourette syndrome (GTS) is known to involve corticostriatal loops possibly under genetic control. Less is known about possible environmental triggers of GTS. Specifically, immune-related events following possible environmental inducers have been evoked, but important controversies still exist. In this systematic review and meta-analysis, we looked for evidence in favor of such possibilities.

METHODS

We performed a systematic review and meta-analysis of all immunological data in PubMed.

RESULTS

We found large discrepancies concerning immune dysfunctions in GTS, and meta-analyzing cytokines data did not allow us to conclude there is an involvement of specific cytokines in GTS neurobiology. When looking specifically at pediatric autoimmune neuropsychiatric disorder associated with streptococcus/pediatric acute onset neuropsychiatric syndrome, we found some important evidence of a possible infectious involvement but in a limited number of studies. Our meta-analysis found an increased level of anti-streptolysin O antibodies in GTS patients, but the level of anti-DNase B antibodies was not increased.

CONCLUSIONS

Too many questions still exist to allow us to definitively reach the conclusion that there is an infectious and immunological etiology in GTS. Much work is still needed to elucidate the possible role of immunology in GTS neurobiology and to favor immunological treatment rather than classical treatment.

Requirements for a Robust Animal Model to Investigate the Disease Mechanism of Autoimmune Complications Associated With ARF/RHD

The pathogenesis of Acute Rheumatic Fever/Rheumatic Heart Disease (ARF/RHD) and associated neurobehavioral complications including Sydenham's chorea (SC) is complex. Disease complications triggered by Group A streptococcal (GAS) infection are confined to human and determining the early events leading to pathology requires a robust animal model that reflects the hallmark features of the disease. However, modeling these conditions in a laboratory animal, of a uniquely human disease is challenging. Animal models including cattle, sheep, pig, dog, cat, guinea pigs rats and mice have been used extensively to dissect molecular mechanisms of the autoimmune inflammatory responses in ARF/RHD. Despite the characteristic limitations of some animal models, several rodent models have significantly contributed to better understanding of the fundamental mechanisms underpinning features of ARF/RHD. In the Lewis rat autoimmune valvulitis model the development of myocarditis and valvulitis with the infiltration of mononuclear cells along with generation of antibodies that cross-react with cardiac tissue proteins following exposure to GAS antigens were found to be similar to ARF/RHD. We have recently shown that Lewis rats injected with recombinant GAS antigens simultaneously developed cardiac and neurobehavioral changes. Since ARF/RHD is multifactorial in origin, an animal model which exhibit the characteristics of several of the cardinal diagnostic criteria observed in ARF/RHD, would be advantageous to determine the early immune responses to facilitate biomarker discovery as well as provide a suitable model to evaluate treatment options, safety and efficacy of vaccine candidates. This review focuses on some of the common small animals and their advantages and limitations.

Immunological Dysfunction in Tourette Syndrome and Related Disorders

Chronic tic disorder and Tourette syndrome are common childhood-onset neurological diseases. However, the pathophysiology underlying these disorders is unclear, and most studies have focused on the disinhibition of the corticostriatal–thalamocortical circuit. An autoimmune dysfunction has been proposed in the pathogenetic mechanism of Tourette syndrome and related neuropsychiatric disorders such as obsessive–compulsive disorder, autism, and attention-deficit/hyperactivity disorder. This is based on evidence from animal model studies and clinical findings. Herein, we review and give an update on the clinical characteristics, clinical evidence, and genetic studies in vitro as well as animal studies regarding immune dysfunction in Tourette syndrome.

Ningdong Granule Upregulates the Striatal DA Transporter and Attenuates Stereotyped Behavior of Tourette Syndrome in Rats

This study aimed to evaluate the possible mechanism of Ningdong granule (NDG) for the treatment of Tourette syndrome (TS). The rats with stereotyped behavior were established by microinjection with TS patients' sera; then, the model rats were divided into NDG and haloperidol (Hal) group, and the nonmedication model rats were regarded as treatment control (TS group). The stereotyped behavior of the rats was recorded, the level of dopamine (DA) in striatum, and the content of homovanillic acid (HVA) in sera were tested, and dopamine transporter (DAT) expression was measured in the study. The experimental results showed that NDG effectively inhibited the stereotyped behavior (P < 0.01), decreased the levels of DA in the striatum (P < 0.05), increased the content of sera HVA (P < 0.01), and enhanced the protein and mRNA expression of DAT in the striatum (P < 0.01). Additionally, the results also revealed Hal could improve the stereotyped behavior as well but had no remarkable influence on DAT expression and DA metabolism. In conclusion, NDG attenuates stereotyped behavior, and its mechanism of action might be associated with the upregulation of DAT expression to regulate DA metabolism in the brain.

Choline acetyltransferase may contribute to the risk of Tourette syndrome: Combination of family-based analysis and case-control study

OBJECTIVES

Twin and family analyses have revealed a genetic contribution to Tourette syndrome (TS) and post-mortem studies have raised the intriguing possibility of a reduction in cholinergic interneuronsin TS patients.

METHODS

We selected five tag SNPs (rs100824791, rs12264845, rs1880676, rs3793790 and rs3793798) of choline acetyltransferase (CHAT) from the Han Chinese population Hapmap database. Genotyping was conducted on 401 TS nuclear family trios and 405 control subjects. Transmission disequilibrium test (TDT) and haplotype relative risk (HRR) analyses were used to analyse the family-based study and a case-control study was also used to assess the genetic susceptibility to TS.

RESULTS

The results revealed a significant over-transmission of rs3793790 (TDT, χ²=9.121, P = 0.003; HRR, χ²=6.579, P = 0.01), while case-control analysis found no differences between the two groups (genotype, χ²=0.436, P = 0.804; allele, χ²=0.149, P = 0.700). Also, rs3793798 also indicated a positive association associated with TS (TDT, χ²=5.025, P = 0.028; HRR, χ²=0.250, P = 0.617). However, the other three SNPs investigated were found not to be associated with TS in both in the family-based and case-control studies.

CONCLUSIONS

Our association analysis demonstrates that CHAT may contribute to TS susceptibility in the Han Chinese population. This gives strong support to the involvement of cholinergic interneurons in the aetiology of TS and reveals a potential therapeutic target.

Postnatal low-concentration arsenic exposure induces autism-like behavior and affects frontal cortex neurogenesis in rats

This study aimed to explore the effects of postnatal low-concentration arsenic exposure on learning, social skills and frontal cortex neurogenesis in rats. Water-based arsenic exposure rat models were established on postnatal days 4-10 (P4-P10). The experimental animals were divided into four groups: the control group, a 15 μg/L As₂O₃ water group, a 30 μg/L As₂O₃ water group, and a 45 μg/L As₂O₃ water group. Cognitive function was examined with the Morris water maze, anxiety-like behavior with the open field test and light-dark box test, and social skills with a social interaction test. The frontal cortices of pups from each experimental group were sectioned at various time points after arsenic exposure. The morphologies and neurogenesis of the neurons in the frontal cortices were observed by hematoxylin-eosin staining, Nissl staining, and doublecortin (DCX) immunostaining. Significant positive correlations between arsenic concentration and deficits in learning and social skills were found, and the arsenic exposure groups showed significant increases in anxiety-like behavior compared with the control group (all Ps<0.05). Abnormal morphologic changes in the external granular layer and external pyramidal layer were positively correlated with the water arsenic concentration in the acute phase of arsenic exposure. However, at five weeks after arsenic exposure, the frontal cortex morphology was restored. Moreover, immunohistochemistry revealed that compared to the control group, the groups that were exposed to arsenic exhibited significantly higher levels of DCX expression in the external granular and external pyramidal layers (all Ps<0.001). Furthermore, the 30 μg/L and 45 μg/L arsenic exposure groups still showed some DCX expression at five weeks after exposure. In conclusion, postnatal low-concentration arsenic exposure impaired learning and social skills and increased anxiety-like behaviors, and abnormal frontal cortex neurogenesis may be the mechanism underlying these effects.

Biological markers for anxiety disorders, OCD and PTSD: A consensus statement. Part II: Neurochemistry, neurophysiology and neurocognition

OBJECTIVE

Biomarkers are defined as anatomical, biochemical or physiological traits that are specific to certain disorders or syndromes. The objective of this paper is to summarise the current knowledge of biomarkers for anxiety disorders, obsessive-compulsive disorder (OCD) and posttraumatic stress disorder (PTSD).

METHODS

Findings in biomarker research were reviewed by a task force of international experts in the field, consisting of members of the World Federation of Societies for Biological Psychiatry Task Force on Biological Markers and of the European College of Neuropsychopharmacology Anxiety Disorders Research Network.

RESULTS

The present article (Part II) summarises findings on potential biomarkers in neurochemistry (neurotransmitters such as serotonin, norepinephrine, dopamine or GABA, neuropeptides such as cholecystokinin, neurokinins, atrial natriuretic peptide, or oxytocin, the HPA axis, neurotrophic factors such as NGF and BDNF, immunology and CO2 hypersensitivity), neurophysiology (EEG, heart rate variability) and neurocognition. The accompanying paper (Part I) focuses on neuroimaging and genetics.

CONCLUSIONS

Although at present, none of the putative biomarkers is sufficient and specific as a diagnostic tool, an abundance of high quality research has accumulated that should improve our understanding of the neurobiological causes of anxiety disorders, OCD and PTSD.

Randomized, Controlled Trial of Intravenous Immunoglobulin for Pediatric Autoimmune Neuropsychiatric Disorders Associated With Streptococcal Infections

OBJECTIVE

Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) are hypothesized to occur as a result of cross-reactive antibodies produced in response to group A streptococcal infections. Previous research suggests that immunomodulatory therapies, such as intravenous immunoglobulin (IVIG), may lead to rapid and sustained symptom improvement in patients with PANDAS.

METHOD

A total of 35 children meeting criteria for PANDAS and moderate to severe obsessive-compulsive disorder (OCD) were enrolled in a randomized-entry, double-blind, placebo-controlled, 6-week trial of IVIG (1 g/kg/day on 2 consecutive days), followed by optional open-label treatment for nonresponders, with follow-up at 12 and 24 weeks. Primary outcome measures were the Children's Yale-Brown Obsessive Compulsive Scale (CY-BOCS) and the Clinical Global Impressions-Improvement (CGI-I) rating. "Responders" were defined, a priori, by a ≥ 30% decrease in CY-BOCS total score, and a "much" or "very much" improved rating on CGI-I.

RESULTS

During the double-blind phase, the mean decrease in CY-BOCS score was 24% ± 31% in the IVIG group (n = 17) and 12% ± 27% in the placebo group (n = 18), with six responders in the IVIG group (35%) versus four (22%) in the placebo group; these differences were not statistically significant. Twenty-four participants met criteria for nonresponse to double-blind infusion and received open-label IVIG at week 6. Among all participants, the mean CY-BOCS improvement from baseline was 55% ± 33% at week 12 and 62% ± 33% at week 24.

CONCLUSION

IVIG was safe and well tolerated. Between-group differences were smaller than anticipated, and the double-blind comparison failed to demonstrate superiority of IVIG over placebo. The observed open-label improvements indicate that future trials would benefit from larger sample sizes designed in part to aid in the identification of biomarkers predictive of a positive response to immunotherapy. Future investigations focused on the natural history of PANDAS are also warranted. Clinical trial registration information-Intravenous Immunoglobulin for PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated With Streptococcal Infections); http://clinicaltrials.gov/; NCT01281969ZIAMH002666.

Pediatric Autoimmune Disorders Associated with Streptococcal Infections and Tourette's Syndrome in Preclinical Studies

Accumulating evidence suggests that Tourette's Syndrome (TS) - a multifactorial pediatric disorder characterized by the recurrent exhibition of motor tics and/or vocal utterances - can partly depend on immune dysregulation provoked by early repeated streptococcal infections. The natural and adaptive antibody-mediated reaction to streptococcus has been proposed to potentially turn into a pathological autoimmune response in vulnerable individuals. Specifically, in conditions of increased permeability of the blood brain barrier (BBB), streptococcus-induced antibodies have been proposed to: (i) reach neuronal targets located in brain areas responsible for motion control; and (ii) contribute to the exhibition of symptoms. This theoretical framework is supported by indirect evidence indicating that a subset of TS patients exhibit elevated streptococcal antibody titers upon tic relapses. A systematic evaluation of this hypothesis entails preclinical studies providing a proof of concept of the aforementioned pathological sequelae. These studies shall rest upon individuals characterized by a vulnerable immune system, repeatedly exposed to streptococcus, and carefully screened for phenotypes isomorphic to the pathological signs of TS observed in patients. Preclinical animal models may thus constitute an informative, useful tool upon which conducting targeted, hypothesis-driven experiments. In the present review we discuss the available evidence in preclinical models in support of the link between TS and pediatric autoimmune neuropsychiatric disorders associated with streptococcus infections (PANDAS), and the existing gaps that future research shall bridge. Specifically, we report recent preclinical evidence indicating that the immune responses to repeated streptococcal immunizations relate to the occurrence of behavioral and neurological phenotypes reminiscent of TS. By the same token, we discuss the limitations of these studies: limited evidence of behavioral phenotypes isomorphic to tics and scarce knowledge about the immunological phenomena favoring the transition from natural adaptive immunity to pathological outcomes.

Addressing the Complexity of Tourette's Syndrome through the Use of Animal Models

Tourette's syndrome (TS) is a neurodevelopmental disorder characterized by fluctuating motor and vocal tics, usually preceded by sensory premonitions, called premonitory urges. Besides tics, the vast majority—up to 90%—of TS patients suffer from psychiatric comorbidities, mainly attention deficit/hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). The etiology of TS remains elusive. Genetics is believed to play an important role, but it is clear that other factors contribute to TS, possibly altering brain functioning and architecture during a sensitive phase of neural development. Clinical brain imaging and genetic studies have contributed to elucidate TS pathophysiology and disease mechanisms; however, TS disease etiology still is poorly understood. Findings from genetic studies led to the development of genetic animal models, but they poorly reflect the pathophysiology of TS. Addressing the role of neurotransmission, brain regions, and brain circuits in TS disease pathomechanisms is another focus area for preclinical TS model development. We are now in an interesting moment in time when numerous innovative animal models are continuously brought to the attention of the public. Due to the diverse and largely unknown etiology of TS, there is no single preclinical model featuring all different aspects of TS symptomatology. TS has been dissected into its key symptomst hat have been investigated separately, in line with the Research Domain Criteria concept. The different rationales used to develop the respective animal models are critically reviewed, to discuss the potential of the contribution of animal models to elucidate TS disease mechanisms.

Targeted ablation of cholinergic interneurons in the dorsolateral striatum produces behavioral manifestations of Tourette syndrome

Gilles de la Tourette syndrome (TS) is characterized by tics, which are transiently worsened by stress, acute administration of dopaminergic drugs, and by subtle deficits in motor coordination and sensorimotor gating. It represents the most severe end of a spectrum of tic disorders that, in aggregate, affect ∼ 5% of the population. Available treatments are frequently inadequate, and the pathophysiology is poorly understood. Postmortem studies have revealed a reduction in specific striatal interneurons, including the large cholinergic interneurons, in severe disease. We tested the hypothesis that this deficit is sufficient to produce aspects of the phenomenology of TS, using a strategy for targeted, specific cell ablation in mice. We achieved ∼ 50% ablation of the cholinergic interneurons of the striatum, recapitulating the deficit observed in patients postmortem, without any effect on GABAergic markers or on parvalbumin-expressing fast-spiking interneurons. Interneuron ablation in the dorsolateral striatum (DLS), corresponding roughly to the human putamen, led to tic-like stereotypies after either acute stress or d-amphetamine challenge; ablation in the dorsomedial striatum, in contrast, did not. DLS interneuron ablation also led to a deficit in coordination on the rotorod, but not to any abnormalities in prepulse inhibition, a measure of sensorimotor gating. These results support the causal sufficiency of cholinergic interneuron deficits in the DLS to produce some, but not all, of the characteristic symptoms of TS.

Animal models of tic disorders: a translational perspective

Tics are repetitive, sudden movements and/or vocalizations, typically enacted as maladaptive responses to intrusive premonitory urges. The most severe tic disorder, Tourette syndrome (TS), is a childhood-onset condition featuring multiple motor and at least one phonic tic for a duration longer than 1 year. The pharmacological treatment of TS is mainly based on antipsychotic agents; while these drugs are often effective in reducing tic severity and frequency, their therapeutic compliance is limited by serious motor and cognitive side effects. The identification of novel therapeutic targets and development of better treatments for tic disorders is conditional on the development of animal models with high translational validity. In addition, these experimental tools can prove extremely useful to test hypotheses on the etiology and neurobiological bases of TS and related conditions. In recent years, the translational value of these animal models has been enhanced, thanks to a significant re-organization of our conceptual framework of neuropsychiatric disorders, with a greater focus on endophenotypes and quantitative indices, rather than qualitative descriptors. Given the complex and multifactorial nature of TS and other tic disorders, the selection of animal models that can appropriately capture specific symptomatic aspects of these conditions can pose significant theoretical and methodological challenges. In this article, we will review the state of the art on the available animal models of tic disorders, based on genetic mutations, environmental interventions as well as pharmacological manipulations. Furthermore, we will outline emerging lines of translational research showing how some of these experimental preparations have led to significant progress in the identification of novel therapeutic targets for tic disorders.

The disrupted basal ganglia and behavioural control: an integrative cross-domain perspective of spontaneous stereotypy

Spontaneous stereotypic behaviour (SB) is common in many captive animal species, as well as in humans with some severe psychiatric disorders, and is often cited as being related to general basal ganglia dysfunction. Despite this assertion, there is little in the literature examining SB specifically in terms of the basal ganglia mechanics. In this review, we attempt to fill this gap by offering an integrative, cross-domain perspective of SB by linking what we currently understand about the SB phenotype with the ever-growing literature on the anatomy and functionality of the basal ganglia. After outlining current models of SB from different theoretical perspectives, we offer a broad but detailed overview of normally functioning basal ganglia mechanics, and attempt to link this with current neurophysiological evidence related to spontaneous SB. Based on this we present an empirically derived theoretical framework, which proposes that SB is the result of a dysfunctional action selection system that may reflect dysregulation of excitatory (direct) and inhibitory (indirect and hyperdirect) pathways as well as alterations in mechanisms of behavioural switching. This approach also suggests behaviours that specifically become stereotypic may reflect inbuilt low selection threshold behavioural sequences associated with early development and the species-specific ethogram or, low threshold behavioural sequences that are the result of stress-induced dopamine exposure at the time of performance.

The role of immune mechanisms in Tourette syndrome

Tourette syndrome (TS) is a childhood-onset tic disorder associated with abnormal development of brain networks involved in the sensory and motor processing. An involvement of immune mechanisms in its pathophysiology has been proposed. Animal models based on active immunization with bacterial or viral mimics, direct injection of cytokines or patients' serum anti-neuronal antibodies, and transgenic approaches replicated stereotyped behaviors observed in human TS. A crucial role of microglia in the neural-immune crosstalk within TS and related disorders has been proposed by animal models and confirmed by recent post mortem studies. With analogy to autism, genetic and early life environmental factors could foster the involvement of immune mechanisms to the abnormal developmental trajectories postulated in TS, as well as lead to systemic immune dysregulation in this condition. Clinical studies demonstrate an association between TS and immune responses to pathogens like group A Streptococcus (GAS), although their role as risk-modifiers is still undefined. Overactivity of immune responses at a systemic level is suggested by clinical studies exploring cytokine and immunoglobulin levels, immune cell subpopulations, and gene expression profiling of peripheral lymphocytes. The involvement of autoantibodies, on the other hand, remains uncertain and warrants more work using live cell-based approaches. Overall, a body of evidence supports the hypothesis that disease mechanisms in TS, like other neurodevelopmental illnesses (e.g. autism), may involve dysfunctional neural-immune cross-talk, ultimately leading to altered maturation of brain pathways controlling different behavioral domains and, possibly, differences in organising immune and stress responses. This article is part of a Special Issue entitled SI: Neuroimmunology in Health And Disease.

Behavioral and neural effects of intra-striatal infusion of anti-streptococcal antibodies in rats

Group A β-hemolytic streptococcal (GAS) infection is associated with a spectrum of neuropsychiatric disorders. The leading hypothesis regarding this association proposes that a GAS infection induces the production of auto-antibodies, which cross-react with neuronal determinants in the brain through the process of molecular mimicry. We have recently shown that exposure of rats to GAS antigen leads to the production of anti-neuronal antibodies concomitant with the development of behavioral alterations. The present study tested the causal role of the antibodies by assessing the behavior of naïve rats following passive transfer of purified antibodies from GAS-exposed rats. Immunoglobulin G (IgG) purified from the sera of GAS-exposed rats was infused directly into the striatum of naïve rats over a 21-day period. Their behavior in the induced-grooming, marble burying, food manipulation and beam walking assays was compared to that of naïve rats infused with IgG purified from adjuvant-exposed rats as well as of naïve rats. The pattern of in vivo antibody deposition in rat brain was evaluated using immunofluorescence and colocalization. Infusion of IgG from GAS-exposed rats to naïve rats led to behavioral and motor alterations partially mimicking those seen in GAS-exposed rats. IgG from GAS-exposed rats reacted with D1 and D2 dopamine receptors and 5HT-2A and 5HT-2C serotonin receptors in vitro. In vivo, IgG deposits in the striatum of infused rats colocalized with specific brain proteins such as dopamine receptors, the serotonin transporter and other neuronal proteins. Our results demonstrate the potential pathogenic role of autoantibodies produced following exposure to GAS in the induction of behavioral and motor alterations, and support a causal role for autoantibodies in GAS-related neuropsychiatric disorders.

Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS): An Evolving Concept

Pediatric autoimmune neuropsychiatric disorders associated with streptococcus infections (PANDAS) originated from the observational work of Swedo and collaborators, who formalized their definition in 1998 in a set of operational criteria. The application of these criteria, which focuses on tics and obsessive-compulsive symptoms as core symptoms, has encountered difficulties, eventually leading to a high rate of misdiagnosis. In particular, the core feature represented by the association between newly diagnosed infections and neuropsychiatric symptom relapses in youths with this diagnosis could not be demonstrated by longitudinal studies. Exploratory studies aiming to identify clinical or cognitive features that could discriminate PANDAS from other pediatric obsessive-compulsive and tic disorders present methodological limitations, and therefore are not conclusive. Other behavioral features, in addition to obsessive-compulsive symptoms and tics, have been included in pediatric acute-onset neuropsychiatric syndromes (PANS) and childhood acute neuropsychiatric syndromes (CANS), two new concepts recently proposed in order to define a much broader clinical spectrum encompassing etiologically diverse entities. Given the uncertainties on the clinical definition of PANDAS, it is not surprising that evidence in support of a post-infectious, immune-mediated pathophysiology is also insufficient. Anti-dopamine receptor antibodies might be relevant to both Sydenham's chorea (SC)-the prototypical post-streptococcal neuropsychiatric disorder-and some rare forms of encephalitis targeting the basal ganglia specifically, but studies exploring their association with children fulfilling Swedo's criteria for PANDAS have been inconclusive. Moreover, we lack evidence in favor of the efficacy of antibiotic prophylaxis or tonsillectomy in patients fulfilling Swedo's criteria for PANDAS, whereas a response to immune-mediated treatments like intravenous immunoglobulins has been documented by one study, but needs replication in larger trials. Overall, the available evidence does not convincingly support the concept that PANDAS are a well-defined, isolated clinical entity subdued by definite pathophysiological mechanisms; larger, prospective studies are necessary to reshape the nosography and disease mechanisms of post-streptococcal acute neuropsychiatric disorders other than SC. Research is also under way to shed further light on a possible relationship between streptococcal infections, other biological and psychosocial stressors, and the complex pathobiology of chronic tic disorders.

Influence of mesenchymal stem cell transplantation on stereotypic behavior and dopamine levels in rats with Tourette syndrome

Context

Tourette syndrome (TS) is a heterogeneous neuropsychiatric disorder. Chronic motor and phonic tics are central symptoms in TS patients. For some patients, tics are intractable to any traditional treatment and cause lifelong impairment and life-threatening symptoms. New therapies should be developed to address symptoms and overt manifestations of TS. Transplantation of neurogenic stem cells might be a viable approach in TS treatment.

Objective

We used mesenchymal stem cell (MSC) transplantation to treat TS. We discuss the mechanism of action, as well as the efficiency of this approach, in treating TS.

Settings and Design

An autoimmune TS animal model was adopted in the present study. Forty-eight Wistar rats were randomly allocated to the control group and the 2 experimental groups, namely, TS rats+vehicle and TS rats+MSC. MSCs were co-cultured with 5-bromodeoxyuridine (BrdU) for 24 h for labeling prior to grafting.

Methods

Stereotypic behaviors were recorded at 1, 7, 14, and 28 days after transplantation. Dopamine (DA) content in the striatum of rats in the 3 groups was measured using a high-performance liquid chromatography column equipped with an electrochemical detector (HPLC-ECD) on day 28 after transplantation.

Statistical analysis

Statistical analysis was performed by repeated measurements analysis of variance to evaluate stereotypic behavior counts at different time points.

Results

TS rats exhibited higher stereotypic behavioral counts compared with the control group. One week after transplantation, TS rats with MSC grafts exhibited significantly decreased stereotypic behavior. Rats with MSC grafts also showed reduced levels of DA in the striatum when compared with TS rats, which were exposed only to the vehicle.

Conclusions

Intrastriatal transplantation of MSCs can provide relief from the stereotypic behavior of TS. Our results indicate that this approach may have potential for developing therapies against TS. The mechanism(s) of the observed effect may be related to the suppression of DA system by decreasing the content of DA in TS rats.

Theoretical and practical considerations behind the use of laboratory animals for the study of Tourette syndrome

In the present manuscript we review a substantial body of literature describing several pre-clinical animal models designed and developed with the purpose of investigating the biological determinants of Tourette syndrome (TS). In order to map the animal models onto the theoretical background upon which they have been devised, we first define phenomenological and etiological aspects of TS and then match this information to the available pre-clinical models. Thus, we first describe the characteristic symptoms exhibited by TS patients and then a series of hypotheses attempting to identify the multifactorial causes of TS. With respect to the former, we detail the phenomenology of abnormal repetitive behaviors (tics and stereotypies), obsessive-compulsive behaviors and aberrant sensory-motor gating. With respect to the latter, we describe both potential candidate vulnerability genes and environmental factors (difficult pregnancies, psychosocial stressors and infections). We then discuss how this evidence has been translated in pre-clinical research with respect to both dependent (symptoms) and independent (etiological factors) variables. Thus, while, on the one hand, we detail the methodologies adopted to measure abnormal repetitive and obsessive-compulsive behaviors, and sensory-motor gating, on the other hand, we describe genetic engineering studies and environmental modulations aimed at reproducing the proposed biological determinants in laboratory rodents. A special emphasis is placed upon "programming" events, occurring during critical stages of early development and exerting organizational delayed consequences. In the final section, we outline a heuristic model with the purpose of integrating clinical and pre-clinical evidence in the study of TS.

Anti-Purkinje cell antibody as a biological marker in attention deficit/hyperactivity disorder: a pilot study

An autoimmune hypothesis has been suggested for several disorders in childhood. The aim of the study was to clarify the role of the cerebellum in ADHD and to evaluate the possible association between anti-Yo antibodies and ADHD. The presence/absence of antibodies was tested by indirect immunofluorescence assay on 30 combined subtype ADHD children, on 19 children with other psychiatric disorders (Oppositional-defiant and Conduct Disorders, Dyslexia) and 27 healthy controls. Results showed a significant positive response to the anti-Yo antibody immunoreactivity in the Purkinje cells of the cerebellum of ADHD children, compared with the control group and the psychiatric non-ADHD children. This association points to an immune dysregulation and the involvement of the cerebellum in ADHD.

Immune-mediated animal models of Tourette syndrome

An autoimmune diathesis has been proposed in Tourette syndrome (TS) and related neuropsychiatric disorders such as obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism and anorexia nervosa. Environmental triggers including infection and xenobiotics are hypothesized to lead to the production of brain-directed autoantibodies in a subset of genetically susceptible individuals. Although much work has focused on Group A Streptococcus (GAS), the role of this common childhood infection remains controversial. Animal model studies based on immune and autoantibody findings in TS have demonstrated immunoglobulin (Ig) deposits and stereotypic movements and related behavioral disturbances reminiscent of TS following exposure to GAS, other activators of host anti-microbial responses, soluble immune mediators and anti-GAS or anti-neuronal antibodies. Demonstration of the ability to recreate these abnormalities through passive transfer of serum IgG from GAS-immunized mice into naïve mice and abrogation of this activity through depletion of IgG has provided compelling evidence in support of the autoimmune hypothesis. Immunologically-based animal models of TS are a potent tool for dissecting the pathogenesis of this serious neuropsychiatric syndrome.

Animal models recapitulating the multifactorial origin of Tourette syndrome

Tourette Syndrome (TS) is a neurological disorder characterized by motor and phonic tics affecting approximately 1% of the pediatric population. Behavioral comorbidities often include obsessive-compulsive behavior and impaired attention. The neurobiological substrates associated with TS generally entail abnormalities in neurotransmitter circuitry regulating basal ganglia activity. The neurotransmitters most often associated with TS are dopamine, serotonin, and GABA. TS origin roots in genetic predisposing factors, and environmental variables favoring tic onset and exacerbation. Among the latter, repeated infections with group A beta-hemolytic Streptococcus and psychosocial stressors encountered during development have been proposed to constitute likely susceptibility factors. In this chapter, we describe how this clinical/epidemiological knowledge has been translated into animal models of TS. Specifically, we review several studies attempting to reproduce TS-like symptoms (tics and behavioral stereotypies) and comorbidities (impaired attention, increased locomotion, and perseverative responding) in laboratory rodents. Additionally, we discuss studies in which the genetic and environmental predisposing factors have been modeled in experimental subjects. Ultimately, we propose a unifying perspective recapitulating dependent and independent variables in the preclinical study of TS and discuss its potential theoretical and heuristic implications.

Behavioral, pharmacological, and immunological abnormalities after streptococcal exposure: a novel rat model of Sydenham chorea and related neuropsychiatric disorders

Group A streptococcal (GAS) infections and autoimmunity are associated with the onset of a spectrum of neuropsychiatric disorders in children, with the prototypical disorder being Sydenham chorea (SC). Our aim was to develop an animal model that resembled the behavioral, pharmacological, and immunological abnormalities of SC and other streptococcal-related neuropsychiatric disorders. Male Lewis rats exposed to GAS antigen exhibited motor symptoms (impaired food manipulation and beam walking) and compulsive behavior (increased induced-grooming). These symptoms were alleviated by the D2 blocker haloperidol and the selective serotonin reuptake inhibitor paroxetine, respectively, drugs that are used to treat motor symptoms and compulsions in streptococcal-related neuropsychiatric disorders. Streptococcal exposure resulted in antibody deposition in the striatum, thalamus, and frontal cortex, and concomitant alterations in dopamine and glutamate levels in cortex and basal ganglia, consistent with the known pathophysiology of SC and related neuropsychiatric disorders. Autoantibodies (IgG) of GAS rats reacted with tubulin and caused elevated calcium/calmodulin-dependent protein kinase II signaling in SK-N-SH neuronal cells, as previously found with sera from SC and related neuropsychiatric disorders. Our new animal model translates directly to human disease and led us to discover autoantibodies targeted against dopamine D1 and D2 receptors in the rat model as well as in SC and other streptococcal-related neuropsychiatric disorders.

Hyperpolarisation-activated cyclic nucleotide channel 4 (HCN4) involvement in Tourette's syndrome autoimmunity

OBJECTIVES

We previously found that antibodies in Tourette's syndrome (TS) patients' sera reacted with a 120 kDa protein from rat brain tissue. Here, we sought to identify this protein and determine if it was involved in TS pathogenesis.

METHODS

The 120 kDa protein was identified using immunoprecipitation, Western blotting, and mass spectrometry. ELISAs were used to quantify anti-120 kDa protein antibodies in serum of interest using samples from 32 TS patients, 47 patients with attention deficit hyperactivity disorder (ADHD) and 14 healthy controls. Involvement of the 120 kDa protein in TS was confirmed using co-localisation assays with GH3 cells. TS sera were micro-infused into SD rats' brain striatum and their stereotypical behaviours were monitored.

RESULTS

The brain protein was identified as hyperpolarisation-activated cyclic nucleotide channel 4 (HCN4). TS patients' sera contained significantly more anti-HCN4 antibodies than ADHD patient and control sera. After microinfusing TS serum, SD rats exhibited increased stereotyped tic behaviours, which were correlated with the amount of infused anti-HCN4 antibody.

CONCLUSIONS

Anti-HCN4 antibodies in the brain might contribute to the pathogenesis of tic symptoms in TS patients. However, further studies are needed to investigate the validity of this animal model of TS induced by microinfusing anti-HCN4 antibody.

Anti-streptococcus IgM antibodies induce repetitive stereotyped movements: cell activation and co-localization with Fcα/μ receptors in the striatum and motor cortex

Group A beta-hemolytic streptococcus (GABHS) infections are implicated in neuropsychiatric disorders associated with an increased expression of repetitive stereotyped movements. Anti-streptococcus IgG presumably cross-reacts with elements on basal ganglia cells, modifies their function, and triggers symptoms. IgM may play a unique role in precipitating behavioral disturbances since variations in cortico-striatal activity occur in temporal congruity with peak IgM titers during an orchestrated immune response. We discovered in Balb/c mice that single subcutaneous injections of mouse monoclonal IgM antibodies to streptococcus group A bacteria induce marked dose-dependent increases in repetitive stereotyped movements, including head bobbing, sniffing, and intense grooming. Effects were antibody- and antigen-specific: anti-streptococcus IgG stimulated ambulatory activity and vertical activity but not these stereotypies, while anti-KLH IgM reduced activity. We suggest that anti-streptococcus IgM and IgG play unique roles in provoking GABHS-related behavioral disturbances. Paralleling its stereotypy-inducing effects, anti-streptococcus IgM stimulated Fos-like immunoreactivity in regions linked to cortico-striatal projections involved in motor control, including subregions of the caudate, nucleus accumbens, and motor cortex. This is the first evidence that anti-streptococcus IgM antibodies induce in vivo functional changes in these structures. Moreover, there was a striking similarity in the distributions of anti-streptococcus IgM deposits and Fos-like immunoreactivity in these regions. Of further importance, Fcα/μ receptors, which bind IgM, were present- and co-localized with anti-streptococcus IgM in these structures. We suggest that anti-streptococcus IgM-induced alterations of cell activity reflect local actions of IgM that involve Fcα/μ receptors. These findings support the use of anti-streptococcus monoclonal antibody administration in Balb/c mice to model GABHS-related behavioral disturbances and identify underlying mechanisms.

Neurobiology of tourette syndrome: current status and need for further investigation

Tourette syndrome (TS) is a common, chronic neuropsychiatric disorder characterized by the presence of fluctuating motor and phonic tics. The typical age of onset is ∼5-7 years, and the majority of children improve by their late teens or early adulthood. Affected individuals are at increased risk for the development of various comorbid conditions, such as obsessive-compulsive disorder, attention deficit hyperactivity disorder, school problems, depression, and anxiety. There is no cure for tics, and symptomatic therapy includes behavioral and pharmacological approaches. Evidence supports TS being an inherited disorder; however, the precise genetic abnormality remains unknown. Pathologic involvement of cortico-striatal-thalamo-cortical (CSTC) pathways is supported by neurophysiological, brain imaging, and postmortem studies, but results are often confounded by small numbers, age differences, severity of symptoms, comorbidity, use of pharmacotherapy, and other factors. The primary site of abnormality remains controversial. Although numerous neurotransmitters participate in the transmission of messages through CSTC circuits, a dopaminergic dysfunction is considered a leading candidate. Several animal models have been used to study behaviors similar to tics as well as to pursue potential pathophysiological deficits. TS is a complex disorder with features overlapping a variety of scientific fields. Despite description of this syndrome in the late 19th century, there remain numerous unanswered neurobiological questions.

Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infection (PANDAS): a Controversial Diagnosis

Despite more than a decade of studying pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS), it is still not possible to confirm its existence and whether it is a poststreptococcal autoimmune disorder. Many controversies remain: the diagnostic criteria have not been validated, evidence of autoimmunity remains inconclusive, evidence of a genetic predisposition is weak, and streptococcal infections are common in childhood and could represent only a trigger of exacerbations of tics and obsessive-compulsive disorder. Patients who fit the PANDAS criteria appear to represent a subgroup of children with chronic tic disorder and/or obsessive-compulsive disorder who may experience symptom exacerbations after group A β-hemolytic streptococci infections; however, those infections are not the sole or even the most common antecedent of exacerbations. There is not enough evidence to support PANDAS as a unique clinical entity.

Striatal microinjection of Sydenham chorea antibodies: using a rat model to examine the dopamine hypothesis

We hypothesized that injection of anti-basal antibodies from patients with Sydenham's chorea into rats' striatum will induce behavioral and histological changes. Antibodies from eight Sydenham's chorea patients and eight age-matched controls were injected into the left caudate of 16 rats. Apomorphine- and amphetamine-induced rotations were performed on days 10 and 17, respectively, followed by immunohistochemical studies. Antibodies from patients with Sydenham's chorea, but not controls, bound to a ∼50-kDa molecule in the striatum extract; immunohistology staining demonstrated specific binding to cellular component(s) in rats' striatum. Contrary to our hypothesis, we could not detect in the rats injected with Sydenham's chorea antibodies changes in rotational behavior or immunohistochemistry staining for dopaminergic or GABAergic markers. Injection of small quantities of anti-neuronal antibodies present in patients with Sydenham's chorea into rat striatum is insufficient to alter motor behavior or cause detectable cellular changes.

The immunobiology of Tourette's disorder, pediatric autoimmune neuropsychiatric disorders associated with Streptococcus, and related disorders: a way forward

Obsessive-compulsive disorder (OCD) and related conditions including Tourette's disorder (TD) are chronic, relapsing disorders of unknown etiology associated with marked impairment and disability. Associated immune dysfunction has been reported and debated in the literature since the late 80s. The immunologic culprit receiving the most interest has been Group A Streptococcus (GAS), which began to receive attention as a potential cause of neuropsychiatric symptoms, following the investigation of the symptoms reported in Sydenham's chorea (SC) and rheumatic fever, such as motor tics, vocal tics, and both obsessive-compulsive and attention deficit/hyperactivity symptoms. Young children have been described as having a sudden onset of these neuropsychiatric symptoms temporally associated with GAS, but without supporting evidence of rheumatic fever. This presentation of OCD and tics has been termed pediatric autoimmune neuropsychiatric disorders associated with Streptococcus (PANDAS). Of note, SC, OCD, and TD often begin in early childhood and share common anatomic areas--the basal ganglia of the brain and the related cortical and thalamic sites--adding support to the possibility that these disorders might share a common immunologic and/or genetic vulnerability. Relevant manuscripts were identified through searches of the PsycINFO and MedLine databases using the following keywords: OCD, immune, PANDAS, Sydenham chorea, Tourette's disorder Group A Streptococcus. Articles were also identified through reference lists from research articles and other materials on childhood OCD, PANDAS, and TD between 1966 and December 2010. Considering the overlap of clinical and neuroanatomic findings among these disorders, this review explores evidence regarding the immunobiology as well as the relevant clinical and therapeutic aspects of TD, OCD, and PANDAS.

Streptococcal upper respiratory tract infections and psychosocial stress predict future tic and obsessive-compulsive symptom severity in children and adolescents with Tourette syndrome and obsessive-compulsive disorder

BACKGROUND

One goal of this prospective longitudinal study was to identify new group A beta-hemolytic streptococcal infections (GABHS) in children and adolescents with Tourette syndrome (TS) and/or obsessive-compulsive disorder (OCD) compared with healthy control subjects. We then examined the power of GABHS infections and measures of psychosocial stress to predict future tic, obsessive-compulsive (OC), and depressive symptom severity.

METHODS

Consecutive ratings of tic, OC, and depressive symptom severity were obtained for 45 cases and 41 matched control subjects over a 2-year period. Clinical raters were blinded to the results of laboratory tests. Laboratory personnel were blinded to case or control status and clinical ratings. Structural equation modeling for unbalanced repeated measures was used to assess the sequence of new GABHS infections and psychosocial stress and their impact on future symptom severity.

RESULTS

Increases in tic and OC symptom severity did not occur after every new GABHS infection. However, the structural equation model found that these newly diagnosed infections were predictive of modest increases in future tic and OC symptom severity but did not predict future depressive symptom severity. In addition, the inclusion of new infections in the model greatly enhanced, by a factor of three, the power of psychosocial stress in predicting future tic and OC symptom severity.

CONCLUSIONS

Our data suggest that a minority of children with TS and early-onset OCD were sensitive to antecedent GABHS infections. These infections also enhanced the predictive power of current psychosocial stress on future tic and OC symptom severity.

The PANDAS subgroup of tic disorders and childhood-onset obsessive-compulsive disorder

Diagnosis and treatment of the PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) variant of Gilles de la Tourette syndrome (GTS) and childhood-onset obsessive-compulsive disorder (OCD) are still controversial issues. Most cross-sectional studies confirm a significant association between GTS and the development of an immune response against group A beta-hemolytic streptococcus (GABHS). Moreover, longitudinal retrospective studies suggest that a recent exposure to GABHS might be a risk factor for the onset of tics and obsessive-compulsive symptoms. However, further evidence from longitudinal prospective research is needed to verify whether a temporal association between GABHS infections and symptom exacerbations is a useful and reliable criterion for the diagnosis of PANDAS. In addition, preliminary results suggest that the PANDAS spectrum might be enlarged to include attention deficit/hyperactivity disorder. Although a number of immunological biomarkers have been proposed as markers of the PANDAS variant, at present, none of these has been conclusively proved useful to diagnose and monitor disease course in children with a suspicion of PANDAS. Finally, despite their empirical use in community settings, we still lack conclusive, evidence-based data regarding the usefulness of antibiotic and immunomodulatory treatments in children with PANDAS. Given the relevance of this topic for general pediatric health, additional research efforts to solve all the pending issues and the hottest points of debate are warranted.

Immunopathogenic mechanisms in tourette syndrome: A critical review

Tourette syndrome (TS) has a multifactorial etiology, in which genetic, environmental, immunological and hormonal factors interact to establish vulnerability. This review: (i) summarizes research exploring the exposure of TS patients to immune-activating environmental factors, and (ii) focuses on recent findings supporting a role of the innate and adaptive immune systems in the pathogenesis of TS and related disorders. A higher exposure prior to disease onset to group A beta-haemolytic streptococcal (GABHS) infections in children with tics and obsessive-compulsive (OC) symptoms has been documented, although their influence upon the course of disease remains uncertain. Increased activation of immune responses in TS is suggested by changes in gene expression profiles of peripheral immune cells, relative frequency of lymphocyte subpopulations, and synthesis of immune effector molecules. Increased activity of cell-mediated mechanisms is suggested by the increased expression of genes controlling natural killer and cytotoxic T cells, increased plasma levels of some pro-inflammatory cytokines which correlate with disease severity, and increased synthesis of antineuronal antibodies. Important methodological differences might account for some inconsistency among results of studies addressing autoantibodies in TS. Finally, a general predisposition to autoimmune responses in TS patients is indicated by the reduced frequency of regulatory T cells, which induce tolerance towards self-antigens. Although the pathogenic role of immune activation in TS has not been definitively proven, a pathophysiological model is proposed to explain the possible effect of immunity upon dopamine transmission regulation and the generation of tics.

Anti-brain antibodies in adult patients with obsessive-compulsive disorder

BACKGROUND

An autoimmune hypothesis has been suggested for a subtype of Obsessive-Compulsive Disorder (OCD) with childhood onset: obsessions, compulsions and/or tics would result from anti-streptococcal antibodies that cross-react with basal ganglia tissue based on molecular mimicry. Consistent with this hypothesis anti-brain antibodies were detected in sera of children with OCD and/or Tourette's syndrome. In the present study, we tested whether adults with OCD have anti-brain antibodies or other antibodies that serve as markers of autoimmunity.

METHODS

Seventy-four DSM-IV OCD (YBOCS> or =16) subjects were recruited and compared to 44 controls with a current Major Depressive Episode for neurological symptoms, ALSO titres, anti-tissue and anti-thyroid antibodies. Anti-brain antibodies were tested by immunohistochemistry and Western blotting methods.

RESULTS

The proportion of subjects with tic comorbidity or positive ASLO titre (>200 IU/ml) was significantly greater in OCD than in MDE patients (21.6 vs. 2.3% and 16.3 vs. 2.3%, respectively). No other differences in antibody parameters were found. 4/74 OCD patients (5.4%) and none of the controls resulted positive for anti-brain antibodies, with a band around 50-60 kDa at the Western blot analysis.

LIMITATIONS

The methodology used to assess anti-brain antibodies.

CONCLUSIONS

The majority of adult OCD patients do not seem to have autoimmunity disturbances as compared to a control group. However, a greater percentage of subjects with positive ASLO titres were found among OCD patients. For a small proportion of OCD patients, moreover, autoimmune reactions towards neuronal structures are present although further investigations are needed to demonstrate its etiopathogenetic relevance.

Children with obsessive-compulsive disorder: are they just "little adults"?

Childhood-onset obsessive-compulsive disorder (OCD) affects 1%-2% of children and adolescents. It is characterized by recurrent obsessions and compulsions that create distress and interfere with daily life. The symptoms reported by children are similar to those seen among individuals who develop OCD in adulthood, and the two groups of patients are treated with similar symptom-relieving behavior therapies and medications. However, there are differences in sex ratios, patterns of comorbidity, and the results of neuroimaging studies that might be important. Here we review the diagnosis and treatment of childhood-onset OCD in light of pediatric and adult studies. We also discuss current knowledge of the pathophysiology of the disorder. Despite advances in this area, further research is needed to understand better the etiopathogenesis of the disorder and to develop new, more effective therapeutic options.

Movement disorders

Abnormal involuntary movements are major features of a large group of neurologic disorders, some of which are neurodegenerative and pose a significant diagnostic and treatment challenge to treating physicians. This article presents a concise review of clinical features, pathogenesis, epidemiology, and management of seven of the most common movement disorders encountered in a primary care clinic routinely. The disorders discussed are Parkinson disease, essential tremor, restless legs syndrome, Huntington disease, drug-induced movement disorder, Wilson disease, and Tourette syndrome.

The neural bases of obsessive-compulsive disorder in children and adults

Functional imaging studies have reported with remarkable consistency hyperactivity in the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and caudate nucleus of patients with obsessive-compulsive disorder (OCD). These findings have often been interpreted as evidence that abnormalities in cortico-basal ganglia-thalamo-cortical loops involving the OFC and ACC are causally related to OCD. This interpretation remains controversial, however, because such hyperactivity may represent either a cause or a consequence of the symptoms. This article analyzes the evidence for a causal role of these loops in producing OCD in children and adults. The article first reviews the strong evidence for anatomical abnormalities in these loops in patients with OCD. These findings are not sufficient to establish causality, however, because anatomical alterations may themselves be a consequence rather than a cause of the symptoms. The article then reviews three lines of evidence that, despite their own limitations, permit stronger causal inferences: the development of OCD following brain injury, pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection, and neurosurgical lesions that attenuate OCD. Converging evidence from these various lines of research supports a causal role for the cortico-basal ganglia-thalamo-cortical loops that involve the OFC and ACC in the pathogenesis of OCD in children and adults.

Pediatric autoimmune neuropsychiatric disorders associated with streptococcus: comparison of diagnosis and treatment in the community and at a specialty clinic

OBJECTIVES

This study aimed to examine whether pediatric autoimmune neuropsychiatric disorders associated with streptococcus were appropriately diagnosed in the community and to determine subsequent rates of unwarranted use of antibiotic treatment for tics and obsessive-compulsive symptoms without the identification of an infection.

METHODS

The design was a retrospective, cross-sectional, observational study of 176 children and adolescents who were evaluated in a specialty program for tics, Tourette's disorder, and related problems. Previously published diagnostic criteria were used to establish the diagnosis of pediatric autoimmune neuropsychiatric disorders associated with streptococcus in our clinic.

RESULTS

Subjects were significantly less likely to receive a diagnosis of pediatric autoimmune neuropsychiatric disorders associated with streptococcus at the specialty clinic than in the community. In the community, subjects were significantly more likely to be treated with antibiotics or immunosuppressant medication if they received a diagnosis of pediatric autoimmune neuropsychiatric disorders associated with streptococcus. Of the 27 subjects with a community diagnosis of pediatric autoimmune neuropsychiatric disorders associated with streptococcus who were treated with antibiotics, 22 (82%) were treated without laboratory evidence of an infection; 2 were treated with immunomodulatory medications.

CONCLUSIONS

Our results support our hypothesis that pediatric autoimmune neuropsychiatric disorders associated with streptococcus are frequently diagnosed in the community without the application of all working diagnostic criteria. This phenomenon has resulted in unwarranted use of antibiotic treatment for tics/obsessive-compulsive disorder without evidence of laboratory infection.

Tourette syndrome and obsessive-compulsive disorder

Tourette syndrome and obsessive-compulsive disorder are neuropsychiatric disorders that have sparked considerable interest over the decades. They are the focus of research for a remarkable diversity of disciplines, ranging from neuroimagers and prenatal epidemiologists to experts in the neural circuits that connect the cortex with the basal ganglia, as well as neuroimmunologists focusing on brain-based autoimmune phenomena. Several hypotheses have been put forward to explain the onset and exacerbation of these illnesses. Here, we discuss the clinical phenomenology and treatment options that are currently available. New psychopharmacological agents are being used that are based on a greater understanding of the neurobiology and are being used in combination with behavioral interventions. Longitudinal clinical investigations into clinical symptoms and the natural course are providing additional clues on the underlying pathophysiology. Recent advances in research models are also reviewed in an attempt to clarify some of the molecular etiologies that lead to these disorders.

Association study between Gilles de la Tourette Syndrome and two genes in the Robo-Slit pathway located in the chromosome 11q24 linked/associated region

Gilles de la Tourette Syndrome (GTS) is an inherited neuropsychiatric disorder characterized by the presence of motor and phonic tics. Previous genetic studies have identified linkage and association between GTS and the 11q24 chromosomal region. We selected for study, within this region, two possible susceptibility genes for GTS, the ROBO3 and ROBO4 genes. These two genes were selected because of the recent identification of SLITRK1 as a potential susceptibility gene for GTS based on a translocation breakpoint and the further finding of two mutations in the SLITRK1 gene in three patients with GTS. While thus far, the SLITRK1 gene appears to account for only a few cases of GTS, these findings, if confirmed, point to other genes in these pathways that may contribute to GTS. Based on this, we examined two genes in the Slit-Robo pathway involved in cell migration, axonal pathfinding, and/or neuronal differentiation because of their location in 11q24, a region previously identified as linked and associated with GTS. We selected six haplotype tagging single nucleotide polymorphisms (SNPs) for ROBO3 and four for ROBO4 and genotyped them in our sample of trios and sibpair families diagnosed with GTS. Based on 155 nuclear families with 255 affected children, we did not find evidence for association between GTS and either the ROBO3 or ROBO4 genes. Thus, these two genes are unlikely to be the susceptibility genes contributing to GTS on 11q24.

Antineuronal antibodies in a group of children with obsessive-compulsive disorder and Tourette syndrome

An autoimmune hypothesis has been suggested for early onset obsessive-compulsive disorder and Tourette syndrome. The term: Paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS) has been proposed as an aetiological subtype of OCD and TS, related to a Group A beta haemolytic streptococcal (GABHS) infection that triggers an autoimmune response. Antineural antibodies have been studied and found in the sera of some patients with these disorders, and they are thought to cross-react with streptococcal and basal ganglia antigens. The present study included 32 prepubertal-onset OCD patients, 21 with TS diagnosis (some of them meeting criteria for PANDAS) and 19 normal children, all aged between 9 and 17 years. Antibodies were assayed by immunohistochemistry and immunoblot. Special attention was paid to the methodology and a high serum dilution was used to minimize non-specific binding. No anti-basal ganglia antibodies were detected by immunohistochemistry in any of the samples. Two proteins, with approximate molecular weights of 86 kDa and 55 kDa, were found in sera from 7 patients. Though the study supports the hypothesis of an autoimmune process underlying OCD or TS in some patients, further research is needed.

A subgroup of Tourette's patients overexpress specific natural killer cell genes in blood: a preliminary report

Gilles de la Tourette Syndrome (TS) is a heritable, neurodevelopmental disorder characterized by motor and vocal tics. As no single gene or region has emerged from standard linkage approaches, TS may result from several as-yet-unidentified genetic factors, and may also occur due to infection-triggered, autoimmune processes. Etiological or pathogenic differences might result in clinically indistinguishable TS subgroups. We have previously used whole genome human oligonucleotide microarrays in an attempt to identify patterns of gene expression in blood linked with TS. In this proof-of-principle study, we applied Principal Components Analysis to a previously collected set of 16 familial TS and 16 control blood samples to identify subgroups. Fourteen genes, primarily Natural Killer Cell (NK) genes, discriminated between TS and all controls. Granzyme B and NKG7 were confirmed using RT-PCR. Five probesets (four genes) reside in chromosomal regions previously linked to familial TS or obsessive-compulsive disorder. Using the 14 genes, a Principal Components Analysis as well as a cluster analysis identified a TS subgroup (n = 10/16) that overexpressed the NK genes. 7/10 subjects within this subgroup were diagnosed with attention-deficit hyperactivity disorder (ADHD), suggesting that this expression profile might be associated with TS and co-morbid ADHD. Principal Components Analysis of gene expression in blood may be useful for identifying subgroups of other complex neurodevelopmental diseases, and the gene expression profile identified in this study may provide a biomarker for at least one subgroup of heritable TS.

Transplantation of rat neural stem cells reduces stereotypic behaviors in rats after intrastriatal microinfusion of Tourette syndrome sera

Tourette syndrome (TS) is a heterogenous neuropsychiatric disorder. In most cases, tics are self-limited or can be treated by behavioral or pharmacological therapy. However, for some individuals, tics can cause lifelong impairment and life-threatening symptoms, which are intractable to traditional treatment. Neural stem cell (NSC) is a potential tool to treat certain neurological diseases. In this study, we proposed to use neural stem cell transplantation as a novel therapy to treat TS and discussed its efficacy. Wistar rats were microinfused with TS sera into the striatum followed by the transplantation of NSCs or vehicle at the infusion site. The sera of the TS patients were identified to have enriched antineural antibodies. Prior to grafting, rat embryonic NSCs were co-cultured with 5-bromodeoxyuridine (Brdu) for 24 h. Stereotypic behaviors were counted at 1, 7, 14 and 21 days after transplantation of NSCs. Morphological analyses revealed that NSCs survived and differentiated into neurons and astrocytes in the striatum 3 weeks after grafting. To sum it up, rat embryonic neural stem cell grafts survived and differentiated in the striatum of TS rat may help relieve stereotypic behaviors of the host. Our results suggest that transplantation of NSCs intrastriatum may have therapeutic potential for TS.

Tourette syndrome and tic disorders: a decade of progress

OBJECTIVE

This is a review of progress made in the understanding of Tourette syndrome (TS) during the past decade including models of pathogenesis, state-of-the-art assessment techniques, and treatment.

METHOD

Computerized literature searches were conducted under the key words "Tourette syndrome," "Tourette disorder," and "tics." Only references from 1996-2006 were included.

RESULTS

Studies have documented the natural history of TS and the finding that tics usually improve by the end of the second decade of life. It has also become clear that TS frequently co-occurs with attention-deficit/hyperactivity disorder), obsessive-compulsive disorder, and a range of other mood and anxiety disorders. These comorbid conditions are often the major source of impairment for the affected child. Advances have also been made in understanding the underlying neurobiology of TS using in vivo neuroimaging and neurophysiology techniques. Progress on the genetic front has been less rapid. Proper diagnosis and education (involving the affected child and his or her parents, teachers, and peers) are essential prerequisites to the successful management of children with TS. When necessary, modestly effective antitic medications are available, although intervening to treat the comorbid attention-deficit/hyperactivity disorder and/or obsessive-compulsive disorder is usually the place to start.

CONCLUSIONS

Prospective longitudinal studies and randomized clinical trials have led to the refinement of several models of pathogenesis and advanced our evidence base regarding treatment options. However, fully explanatory models are needed that would allow for more accurate prognosis and the development of targeted and efficacious treatments.

How relevant are GFAP autoantibodies in autism and Tourette Syndrome?

Controversy exists over the role of autoantibodies to central nervous system antigens in autism and Tourette Syndrome. We investigated plasma autoantibody titers to glial fibrillary acidic protein (GFAP) in children with classic onset (33) and regressive onset (26) autism, controls (25, healthy age- and gender-matched) and individuals with Tourette Syndrome (24) by enzyme-linked immunosorbent assays. We found a significant difference in autoantibody titers to GFAP, not accounted for by age, between the Tourette (significantly lower) and regressive autism groups. However, no differences were found between: classic/regressive; classic/controls; classic/Tourette; regressive/controls; or controls/Tourette. Autoantibody responses against GFAP are unlikely to play a pathogenic role in autism or Tourette Syndrome.