Microinfusion of antineuronal antibodies into rodent striatum: failure to differentiate between elevated and low titers

Autoantibodies in patients with obsessive-compulsive disorder: a systematic review

Obsessive-compulsive disorder (OCD) is a frequent and debilitating mental illness. Although efficacious treatment options are available, treatment resistance rates are high. Emerging evidence suggests that biological components, especially autoimmune processes, may be associated with some cases of OCD and treatment resistance. Therefore, this systematic literature review summarizing all case reports/case series as well as uncontrolled and controlled cross-sectional studies investigating autoantibodies in patients with OCD and obsessive-compulsive symptoms (OCS) was performed. The following search strategy was used to search PubMed: "(OCD OR obsessive-compulsive OR obsessive OR compulsive) AND (antib* OR autoantib* OR auto-antib* OR immunoglob* OR IgG OR IgM OR IgA)". Nine case reports with autoantibody-associated OCD/OCS were identified: five patients with anti-neuronal autoantibodies (against N-methyl-D-aspartate-receptor [NMDA-R], collapsin response mediator protein [CV2], paraneoplastic antigen Ma2 [Ma2], voltage gated potassium channel complex [VGKC], and "anti-brain" structures) and four with autoantibodies associated with systemic autoimmune diseases (two with Sjögren syndrome, one with neuropsychiatric lupus, and one with anti-phospholipid autoantibodies). Six patients (67%) benefited from immunotherapy. In addition, eleven cross-sectional studies (six with healthy controls, three with neurological/psychiatric patient controls, and two uncontrolled) were identified with inconsistent results, but in six studies an association between autoantibodies and OCD was suggested. In summary, the available case reports suggest an association between OCD and autoantibodies in rare cases, which has been supported by initial cross-sectional studies. However, scientific data is still very limited. Thus, further studies on autoantibodies investigated in patients with OCD compared with healthy controls are needed.

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.

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.

An expert opinion on PANDAS/PANS: highlights and controversies

OBJECTIVES

'Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections' (PANDAS) identified a unique subgroup of patients with abrupt onset of obsessive compulsive disorder (OCD) symptoms clinically related to Streptococcus infection and accompanied by neuropsychological and motor symptoms. After almost 20 years, PANDAS has not been accepted as distinct disorder and new criteria for paediatric acute-onset neuropsychiatric syndrome (PANS) have been replaced it, highlighting the fact that several agents rather than only Streptococcus might be involved.

METHODS

Extensive review of the PANDAS/PANS literature was performed on PubMed.

RESULTS

Although antibiotics have been reported to be effective for acute and prophylactic phases in several uncontrolled studies and non-steroidal anti-inflammatory drugs (NSAID) are used during exacerbations, clinical multicenter trials are still missing. Selective serotonin reuptake inhibitors (SSRIs) and cognitive behavioural therapy (CBT) are still the first line of recommendation for acute onset OCD spectrum. Immunological therapies should be restricted to a few cases.

CONCLUSIONS

While PANDAS has found no confirmation as a distinct syndrome, and it is not presented in DSM-5, patients with acute onset OCD spectrum, neurocognitive and motor symptoms should be evaluated for inflammatory, infective, immunological and metabolic abnormalities with a comprehensive diagnostic algorithm.

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.

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 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.

Obsessive-compulsive disorders

Three major changes will probably be introduced in the DSM-5 regarding obsessive-compulsive disorder: OCD will be classified in the diagnostic category 'obsessive-compulsive and related disorders', the clinician should consider the degree of insight into a symptomatology (good to poor insight) and a subtype of tic-related OCD will be introduced. The recommended treatment for OCD is CBT, in severe cases with addition of SSRI treatment.

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.

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.

Infusion of Sydenham's chorea antibodies in striatum with up-regulated dopaminergic receptors: a pilot study to investigate the potential of SC antibodies to increase dopaminergic activity

BACKGROUND

Sydenham's chorea (SC) is a neurological manifestation of rheumatic fever. Autoimmune mechanism of SC is supported by clinical improvement with immunomodulatory therapy; presence of circulating serum anti-basal ganglia antibodies; increase in Th2 group of cytokines in serum and CSF of patients. However, a role of the antibodies in the pathogenesis can only be established by their passive transfer. Chorea is a manifestation clearly related to increased dopaminergic (DA) activity. The purpose of this study was to investigate the potential of antibodies from patients with Sydenham's chorea to cause behavior alterations on rats with unilateral post-synaptic dopamine receptor up-regulation.

METHODS

Rats previously submitted to 6-hydroxidopamine (6-OH-DA) unilateral lesion of substantia nigra pars compacta (SNc) and tested with apomorphine to ensure DA receptors up regulation, received intrastriatal infusion of antibodies from SC patients (n=4) or healthy controls (n=3) during 48 h. 24h post infusion initiation (24PI) and 48 h post infusion initiation (48PI), we registered the occurrence of spontaneous contra lateral rotations (CLR).

FINDINGS

SC group exhibited significantly higher number of CLR than control group at 24PI (p=0.049) and 48PI (p=0.048).

CONCLUSION

The limited sample of the present study restricts us to affirm that SC is really an immune-mediated condition. However the significant result of this pilot study points to preliminary evidence that SC antibodies may affect DA activity in rats with up-regulated striatal DA receptors.

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.

Obsessive-compulsive disorder: a review of the diagnostic criteria and possible subtypes and dimensional specifiers for DSM-V

BACKGROUND

Since the publication of the DSM-IV in 1994, research on obsessive-compulsive disorder (OCD) has continued to expand. It is timely to reconsider the nosology of this disorder, assessing whether changes to diagnostic criteria as well as subtypes and specifiers may improve diagnostic validity and clinical utility.

METHODS

The existing criteria were evaluated. Key issues were identified. Electronic databases of PubMed, ScienceDirect, and PsycINFO were searched for relevant studies.

RESULTS

This review presents a number of options and preliminary recommendations to be considered for DSM-V. These include: (1) clarifying and simplifying the definition of obsessions and compulsions (criterion A); (2) possibly deleting the requirement that people recognize that their obsessions or compulsions are excessive or unreasonable (criterion B); (3) rethinking the clinical significance criterion (criterion C) and, in the interim, possibly adjusting what is considered "time-consuming" for OCD; (4) listing additional disorders to help with the differential diagnosis (criterion D); (5) rethinking the medical exclusion criterion (criterion E) and clarifying what is meant by a "general medical condition"; (6) revising the specifiers (i.e., clarifying that OCD can involve a range of insight, in addition to "poor insight," and adding "tic-related OCD"); and (7) highlighting in the DSM-V text important clinical features of OCD that are not currently mentioned in the criteria (e.g., the major symptom dimensions).

CONCLUSIONS

A number of changes to the existing diagnostic criteria for OCD are proposed. These proposed criteria may change as the DSM-V process progresses.

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.

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.

Obsessive-compulsive disorder and immunology: a review

Interest in the possibility of an immune-mediated pathophysiology of obsessive-compulsive disorder and related disorders has increased. In the late 1980s, the National Institute of Mental Health reported an increase in obsessive-compulsive symptoms (OCS) in patients with Sydenham chorea (SC). Subsequently, a precipitating streptococcal infection in children with sudden onset of OCS but no chorea led to the coining of PANDAS (Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection). This association has furthered interest in biological measures for immune and genetic susceptibility in non-PANDAS obsessive-compulsive disorder patients (OCD). Furthermore, some studies are trying to demonstrate alterations of immune parameters in OCD patients, with few positive results. In this narrative review, our objective was to describe the immunologic findings in OCD, PANDAS, and their association with SC.

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.

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.

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.

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.

Síndromes neuropsiquiátricas pós-estreptocócicas

Nesta revisão narrativa, o nosso objetivo foi descrever as síndromes neuropsiquiátricas pós-estreptocócicas e discuti-las à luz das evidências científicas atuais sobre os possíveis mecanismos patogenéticos envolvidos. Nos últimos anos, uma série de distúrbios do movimento, como tiques, distonia, parkinsonismo, e transtornos psiquiátricos, como o transtorno obsessivo-compulsivo (TOC) e o transtorno de hiperatividade com déficit de atenção (THDA), vem sendo considerada parte do espectro das manifestações pós-estreptocócicas. O termo PANDAS (acrônimo do inglês: pediatric autoimmune neuropsychiatric disorder associated with streptococcus) foi inclusive cunhado para descrever um subgrupo de pacientes com TOC e tiques que exibe flutuação clínica dos sintomas associada a infecção estreptocócica. Entretanto a análise crítica das evidências clinicolaboratoriais não apóia esse espectro ampliado das manifestações pós-estreptocócicas. Apenas na coréia de Sydenham há evidências consistentes de patogênese mediada por processo auto-imune pós-estreptocócico.

Tic disorders and obsessive-compulsive disorder: is autoimmunity involved?

The precise cause of tic disorders and paediatric obsessive-compulsive disorder (OCD) is unknown. In addition to genetic factors, autoimmunity may play a role, possibly as a sequela of preceding streptococcal throat infections in susceptible children. Here we review the most recent findings, from July 2003 onwards, with regard to a possible relationship between tics/OCD and autoimmunity. Evidence about an intriguing correlation between streptococcal infections and tic disorders and OCD is accumulating. Specific criteria have been outlined for paediatric autoimmune disorders associated with streptococcal infections (PANDAS), but autoimmunity may also be involved in tic disorders and/or OCD in general. Anti-basal ganglia auto-antibodies are an important potential indicator of autoimmunity. Although the lack of a standardized methodology makes comparisons of findings difficult, new data has emerged pointing to the possible involvement of specific auto-antigens. Earlier findings of increased D8/17 B cell expression as a putative susceptibility marker could not be replicated, possibly due to instability of the D8/17-binding antibody. Although PANDAS patients have been reported to improve after therapeutic plasma exchange, and antibiotics may prevent symptom exacerbations, immune-based treatments should not be routinely given. In future studies, demonstrating the pathogenetic significance of anti-basal ganglia antibodies in animals is a major challenge to draw any firm conclusions about a role for autoimmunity. Future longitudinal studies should be aimed at assessing the precise relationship between symptom exacerbations, infections, and immune parameters, possibly along with gene expression profiles.