Antineuronal antibody status and phenotype analysis in Tourette's syndrome

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.

What Does Immunology Have to Do With Normal Brain Development and the Pathophysiology Underlying Tourette Syndrome and Related Neuropsychiatric Disorders?

Objective: The goal of this article is to review the past decade's literature and provide a critical commentary on the involvement of immunological mechanisms in normal brain development, as well as its role in the pathophysiology of Tourette syndrome, other Chronic tic disorders (CTD), and related neuropsychiatric disorders including Obsessive-compulsive disorder (OCD) and Attention deficit hyperactivity disorder (ADHD). Methods: We conducted a literature search using the Medline/PubMed and EMBASE electronic databases to locate relevant articles and abstracts published between 2009 and 2020, using a comprehensive list of search terms related to immune mechanisms and the diseases of interest, including both clinical and animal model studies. Results: The cellular and molecular processes that constitute our "immune system" are crucial to normal brain development and the formation and maintenance of neural circuits. It is also increasingly evident that innate and adaptive systemic immune pathways, as well as neuroinflammatory mechanisms, play an important role in the pathobiology of at least a subset of individuals with Tourette syndrome and related neuropsychiatric disorders In the conceptual framework of the holobiont theory, emerging evidence points also to the importance of the "microbiota-gut-brain axis" in the pathobiology of these neurodevelopmental disorders. Conclusions: Neural development is an enormously complex and dynamic process. Immunological pathways are implicated in several early neurodevelopmental processes including the formation and refinement of neural circuits. Hyper-reactivity of systemic immune pathways and neuroinflammation may contribute to the natural fluctuations of the core behavioral features of CTD, OCD, and ADHD. There is still limited knowledge of the efficacy of direct and indirect (i.e., through environmental modifications) immune-modulatory interventions in the treatment of these disorders. Future research also needs to focus on the key molecular pathways through which dysbiosis of different tissue microbiota influence neuroimmune interactions in these disorders, and how microbiota modification could modify their natural history. It is also possible that valid biomarkers will emerge that will guide a more personalized approach to the treatment of these disorders.

Immunity in Gilles de la Tourette-Syndrome: Results From a Cerebrospinal Fluid Study

Background: Several lines of evidence support the hypothesis of an autoimmune origin of Gilles de la Tourette-Syndrome (GTS). Accordingly, in a recent study we detected positive oligoclonal bands (OCB) in cerebrospinal fluid (CSF) in >30% of adult patients indicating an intrathecal antibody synthesis. However, until today no corresponding antibodies could be identified. The aims of this study were to replicate our findings of positive OCB in an independent sample and to detect CSF autoantibodies.

Methods: In this prospective study, 20 adult patients with GTS (male: female = 18:2, median age 36.1 years ± 14.34 SD) were included. All patients were thoroughly clinically characterized. Magnetic Resonance Imaging (MRI) and CSF standard measurements were performed. Isoelectric focusing on polyacrylamide gels with silver staining was used to detect OCB. To examine specific and unspecified autoantibodies, we used transfected Human Embryonic Kidney (HEK) cells expressing different surface antigens (NMDA-, CASPR2-, LGI1-, AMPA-, or GABAB1/B), indirect immunofluorescence on different brain tissue sections, and enzyme-linked visualization. Additionally, we differentiated Glioma stem cells SY5Y (human neuroblastoma) using retinoic acid and astrocytes (rat).

Results: CSF analyses showed positive OCB (type 2) in 4/20 patients (20%). Using transfected HEK cells we did not find specific surface-autoantibodies. Immunohistochemistry on tissue-sections, SY5Y Glioma stem-cells, and astrocytes showed no specific binding patterns either.

Conclusions: Our results corroborate previous findings and demonstrate positive OCB in a substantial number of patients with GTS (prevalence in healthy controls: 5%). Although this is the largest study investigating CSF autoantibodies in GTS using several techniques, we failed to detect any specific or unspecified autoantibodies.

Autoimmunity, Autoantibodies, and Autism Spectrum Disorder

Auism spectrum disorder (ASD) now affects one in 68 births in the United States and is the fastest growing neurodevelopmental disability worldwide. Alarmingly, for the majority of cases, the causes of ASD are largely unknown, but it is becoming increasingly accepted that ASD is no longer defined simply as a behavioral disorder, but rather as a highly complex and heterogeneous biological disorder. Although research has focused on the identification of genetic abnormalities, emerging studies increasingly suggest that immune dysfunction is a viable risk factor contributing to the neurodevelopmental deficits observed in ASD. This review summarizes the investigations implicating autoimmunity and autoantibodies in ASD.

Antibasal Ganglia Antibodies and Antistreptolysin O in Noncomorbid ADHD

OBJECTIVE

An association between streptococcal infections, ABGA positivity, and no comorbidity ADHD (nc-ADHD) has been little investigated. The aim of this study was to evaluate the streptococcal infection frequency, defined entitled serum antistreptolysin O (ASO), and frequency of serum ABGA positivity in a sample of patients with nc-ADHD.

METHOD

In all 40 participants were investigated the ASO titer and ABGA.

RESULTS

The results showed that ABGA positivity was statistically significantly higher in patients affected by ADHD than in patients of a control group, and pathological values of ASO were statistically more frequent in the ADHD group than the control group.

CONCLUSION

These data suggest that streptococcal infections and autoimmune reactions against the basal ganglia are more frequent in ADHD patients than patients in a control group.

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.

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.

Anti-NMDA receptor encephalitis. The disorder, the diagnosis and the immunobiology

Anti-NMDAR encephalitis is a newly characterized syndrome with a progressive, predictable clinical course and the possibility of effective treatment. Accurate and timely diagnosis is critical to selection and implementation of treatments, and optimal patient outcomes. Outcomes are improved with early diagnosis via indirect immunofluorescence or cell-based assays, and the rapid and appropriate administration of immunosuppressant and anti-psychotic therapies. Three possible scenarios accounting for the immunopathogenesis of anti-NMDAR encephalitis are presented, with the most probable one being that of paraneoplastic autoimmunity. Future efforts in this disorder should focus on elucidating the mechanisms that contribute to initiation of this antibody response, as well as exploring the role of tumors, infectious triggers and immune-reactivation. Finally, accessible tools need to be developed that allow for reliable identification of specific antibody markers against synaptic proteins.

Tourette syndrome and other tic disorders

Tic disorders, including Tourette syndrome, are an intriguing group of paroxysmal movement abnormalities that begin in childhood, have a fluctuating course, are capable of causing psychosocial and physical problems, and often improve by early adulthood. These disorders are frequently associated with a variety of comorbid problems whose negative effects may exceed those of tics. Therapy is strictly symptomatic and usually includes educational, behavioral, and a variety of pharmacological therapies. Although there is strong evidence supporting an inherited basis, the precise genetic abnormality remains unknown. A proposed poststreptococcal autoimmune etiology remains controversial. Pathophysiologically, tics appear to arise from an alteration within cortico-striatal-thalamo-cortical circuits, but the definitive site is unknown. Evidence supports an abnormality of synaptic neurotransmission, likely involving the dopaminergic system.

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.

The international prevalence, epidemiology, and clinical phenomenology of Tourette syndrome: a cross-cultural perspective

The overall international prevalence of Tourette syndrome (TS) is 1% in the majority of cultures of the world. Both TS and tics are certainly more obvious and may be more common in younger people. Moreover, TS is seen less frequently in some cultures. However, in all cultures where it has been reported, the phenomenology is similar, highlighting the biological underpinnings of the disorder. This article reviews the international prevalence, epidemiology, and clinical phenomenology of TS, from a cross-cultural perspective.

Adults with Tourette's syndrome with and without attention deficit hyperactivity disorder

OBJECTIVE

Comorbidity between Tourette's syndrome (TS) and attention deficit hyperactivity disorder (ADHD) is high. In children, those with both TS+ADHD fare less well than those with TS-only on measures of both psychopathology and behaviour. The objective of this study was to document such measures in adult patients.

METHOD

Eighty adults with TS-only were compared to 64 with TS+ADHD using a clinical interview and standardised measures of depression, anxiety and obsessionality.

RESULTS

The two groups were no different on measures of TS severity. TS+ADHD patients had significantly more depression, anxiety, obsessive-compulsive behaviour and maladaptive behaviours than patients with TS-only. There were also significant differences in the incidence of copro- and echo-phenomena and family history of ADHD.

CONCLUSION

The finding of increased overall behavioural difficulties and psychopathology in adult patients with TS+ADHD when compared with TS-only is in agreement with previous findings in children with TS. Appropriate treatment of ADHD in TS patients during childhood may prevent many behavioural problems in adulthood.

The prevalence and epidemiology of Gilles de la Tourette syndrome. Part 2: tentative explanations for differing prevalence figures in GTS, including the possible effects of psychopathology, aetiology, cultural differences, and differing phenotypes

As has been demonstrated, Gilles de la Tourette Syndrome (GTS) occurs in at least 1% of the population worldwide. However, earlier studies suggested a lower prevalence. In addition, the prevalence figures for different studies very between 0.4% and 3.8%. Moreover, the prevalence appears to vary in some parts of the world and races, with a lower rate in Afro-Americans and sub-Saharan black Africans. In this the second part of the review, possible reasons for the differences in prevalence and epidemiology are discussed. Tentative explanations for differing prevalence figures in GTS include problems with the diagnosis of GTS, the multidimensional nature of tics, as well as other tic factors including the waxing and waning of symptoms and the suppressibility of symptoms. Other factors inherent to GTS include the fact that there is no diagnostic test and indeed no definitive diagnosis other than clinical, the fact that psychosocial stresses can lead to increased tic severity, and that comorbid disorders may mask tics. The varying methods of study employed can also effect prevalence. There may be some regional differences in GTS as well, which may be due to a lack of awareness of GTS, or it may be a true reflection of low prevalence as in some populations GTS does appear rare. With regard to the sub-Saharan Africa data and possibly the African American data, matters are much more complex than meets the eye. The following reasons are all possible for the apparent rarity in these populations and include (i) other medical priorities and less propensity to seek health care, (ii) lack of awareness of GTS, (iii) chance, (iv) ethnic and epigenetic differences and reasons, (v) genetic and allelic differences in different races, and (vi) an admixture of races. The aetiology of GTS is also complex, with influences from complex genetic mechanisms, pre- and perinatal difficulties and, in a subgroup, some infections, possibly by epigenetic mechanisms. These may well affect phenotype and, thus, prevalence. There have even been suggestions that people with GTS are increasing. Recent data suggests that GTS is not a unitary condition and that there may well be different types of GTS. The prevalence of GTS in these individual subtypes is unknown. It is suggested that a new nomenclature be adopted for GTS in future, pending further genetic and phenomenological studies. To what extent the aetiology affects the phenotype and, thus, the prevalence is still unclear.

Serial immune markers do not correlate with clinical exacerbations in pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections

OBJECTIVE

Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections is hypothesized to be a poststreptococcal autoimmune disorder. If clinical exacerbations are triggered by a streptococcal infection that activates cross-reacting antibodies against neuronal tissue or alters the production of cytokines, then a longitudinal analysis would be expected to identify a correlation between clinical symptoms and a change in autoimmune markers.

PATIENTS AND METHODS

Serial serum samples were available on 12 children with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections participating in a prospective blinded study: 2 samples before an exacerbation point, 1 during the clinical exacerbation, and 2 after the exacerbation. Six subjects had a well-defined clinical exacerbation in association with a documented streptococcal infection, and 6 had a clinical exacerbation without an associated streptococcal infection. All of the serum samples were assayed for antibodies against human postmortem caudate, putamen, and prefrontal cortex; commercially prepared antigens; and complex sugars. Cytokines were measured by 2 different methodologies.

RESULTS

No correlation was identified between clinical exacerbations and autoimmune markers, including: enzyme-linked immunosorbent assay measures of antineuronal antibodies; Western immunoblotting with emphasis on brain region proteins located at 40, 45, and 60 kDa or their corresponding identified antigens; competitive inhibition enzyme-linked immunosorbent assay to evaluate lysoganglioside G(M1) antibodies; and measures of inflammatory cytokines. No differences were identified between individuals with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections with or without exacerbations triggered by streptococcal infections.

CONCLUSIONS

The failure of immune markers to correlate with clinical exacerbations in children with pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections raises serious concerns about the viability of autoimmunity as a pathophysiological mechanism in this disorder.