Microglial Dysregulation in OCD, Tourette Syndrome, and PANDAS

Vitamin D3 improves iminodipropionitrile-induced tic-like behavior in rats through regulation of GDNF/c-Ret signaling activity

Children with chronic tic disorders (CTD), including Tourette syndrome (TS), have significantly reduced serum 25-hydroxyvitamin D [25(OH)D]. While vitamin D3 supplementation (VDS) may reduce tic symptoms in these children, its mechanism is unclear. The study aim was to investigate the effects and mechanisms of vitamin D deficiency (VDD) and VDS on TS model behavior. Forty 5-week-old male Sprague-Dawley rats were randomly divided into (n = 10 each): control, TS model, TS model with VDD (TS + VDD), or TS model with VDS (TS + VDS; two intramuscular injections of 20,000 IU/200 g) groups. The VDD model was diet-induced (0 IU vitamin D/kg); the TS model was iminodipropionitrile (IDPN)-induced. All groups were tested for behavior, serum and striatal 25(OH)D and dopamine (DA), mRNA expressions of vitamin D receptor (VDR), glial cell line-derived neurotrophic factor (GDNF), protooncogene tyrosine-protein kinase receptor Ret (c-Ret), and DA D1 (DRD1) and D2 (DRD2) receptor genes in the striatum. TS + VDD had higher behavior activity scores throughout, and higher total behavior score at day 21 compared with TS model. In contrast, day 21 TS + VDS stereotyped behavior scores and total scores were lower than TS model. The serum 25(OH)D in TS + VDD was < 20 ng/mL, and lower than control. Striatal DA of TS was lower than control. Compared with TS model, striatal DA of TS + VDD was lower, while in TS + VDS it was higher than TS model. Furthermore, mRNA expression of VDR, GDNF, and c-Ret genes decreased in TS model, and GDNF expression decreased more in TS + VDD, while TS + VDS had higher GDNF and c-Ret expressions. VDD aggravates, and VDS ameliorates tic-like behavior in an IDPN-induced model. VDS may upregulate GDNF/c-Ret signaling activity through VDR, reversing the striatal DA decrease and alleviating tic-like behavior.

Cytokine expression profiles in children and adolescents with tic disorders

The etiology of tic disorders (TDs) is not precisely known, although several lines of evidence suggest involvement of the immune system in pathogenesis. Here, we aimed to determine the expression levels of pro-inflammatory and anti-inflammatory cytokines in children with TD and compare them with those of healthy controls. Furthermore, we also evaluated their association with clinical variables in the TD group. Within the study period, 88 children with tic disorders and 111 healthy control children were enrolled. Most children with tic disorders were diagnosed with Tourette's disorder (n = 47, 53.4%) or persistent motor tic disorder (n = 39, 44.3%), while the remainder (n = 2, 2.3%) were diagnosed with persistent vocal tic disorder. We found that children with tic disorders had significantly elevated levels of IL-1β, TNF-α, IL-6 and IL-4 expression, while we detected lower expression levels of IL-17 in children with tic disorders. Our findings provide a molecular landscape of cytokine expression in children with TD, which may suggest a proinflammatory state not affected by the presence of comorbidity and symptom severity. Delineating the contribution of alterations in the immune system to the pathogenesis of tic disorders may pave the way for better therapeutic interventions.

A review of common influencing factors and possible mechanisms associated with allergic diseases complicating tic disorders in children

Over the past few decades, the incidence of childhood allergic diseases has increased globally, and their impact on the affected child extends beyond the allergy itself. There is evidence of an association between childhood allergic diseases and the development of neurological disorders. Several studies have shown a correlation between allergic diseases and tic disorders (TD), and allergic diseases may be an important risk factor for TD. Possible factors influencing the development of these disorders include neurotransmitter imbalance, maternal anxiety or depression, gut microbial disorders, sleep disturbances, maternal allergic status, exposure to tobacco, and environmental factors. Moreover, gut microbial disturbances, altered immunological profiles, and DNA methylation in patients with allergic diseases may be potential mechanisms contributing to the development of TD. An in-depth investigation of the relationship between allergic diseases and TD in children will be important for preventing and treating TD.

Neuronal deletion of Gtf2i results in developmental microglial alterations in a mouse model related to Williams syndrome

Williams syndrome (WS) is a genetic neurodevelopmental disorder caused by a heterozygous microdeletion, characterized by hypersociability and unique neurocognitive abnormalities. Of the deleted genes, GTF2I has been linked to hypersociability in WS. We have recently shown that Gtf2i deletion from forebrain excitatory neurons, referred to as Gtf2i conditional knockout (cKO) mice leads to multi-faceted myelination deficits associated with the social behaviors affected in WS. These deficits were potentially mediated also by microglia, as they present a close relationship with oligodendrocytes. To study the impact of altered myelination, we characterized these mice in terms of microglia over the course of development. In postnatal day 30 (P30) Gtf2i cKO mice, cortical microglia displayed a more ramified state, as compared with wild type (controls). However, postnatal day 4 (P4) microglia exhibited high proliferation rates and an elevated activation state, demonstrating altered properties related to activation and inflammation in Gtf2i cKO mice compared with control. Intriguingly, P4 Gtf2i cKO-derived microglial cells exhibited significantly elevated myelin phagocytosis in vitro compared to control mice. Lastly, systemic injection of clemastine to P4 Gtf2i cKO and control mice until P30, led to a significant interaction between genotypes and treatments on the expression levels of the phagocytic marker CD68, and a significant reduction of the macrophage/microglial marker Iba1 transcript levels in the cortex of the Gtf2i cKO treated mice. Our data thus implicate microglia as important players in WS, and that early postnatal manipulation of microglia might be beneficial in treating inflammatory and myelin-related pathologies.

Biomarkers and Tourette syndrome: a systematic review and meta-analysis

Objective

This research aims to investigate whether peripheral biomarkers might differentiate individuals with Tourette syndrome (TS) from those without the condition.

Methods

A broad range of databases was searched through November 2022. This study employed a systematic literature review and subsequent meta-analysis of case-control studies that assessed the aberration of biomarkers of patients with TS and controls.

Results

A total of 81 studies were identified, out of which 60 met the eligibility criteria for inclusion in the meta-analysis. Following a meticulous screening procedure to determine the feasibility of incorporating case-control studies into the meta-analysis, 13 comparisons were statistically significant [CD3+ T cell, CD4+ T cell, CD4+ T cell to CD8+ T cell ratio, NK-cell, anti-streptolysin O antibodies, anti-DNase antibodies, glutamic acid (Glu), aspartic acid (Asp), ferritin (Fe), zinc (Zn), lead (Pb), vitamin D, and brain-derived neurotrophic factor (BDNF)]. Publication bias was found for anti-streptolysin O antibodies. Suggestive associations were evidenced for norsalsolinol (NSAL), neuron-specific enolase (NSE), and S100B.

Conclusion

In this study, we present empirical evidence substantiating the link between several peripheral biomarkers and the early diagnosis of TS. Larger and more standardized studies are necessary to replicate the observed results, elucidate the specificity of the biomarkers for TS, and evaluate their precision for use in clinical settings.

Hofbauer cells and fetal brain microglia share transcriptional profiles and responses to maternal diet-induced obesity

Maternal immune activation is associated with adverse offspring neurodevelopmental outcomes, many mediated by in utero microglial programming. As microglia remain inaccessible throughout development, identification of noninvasive biomarkers reflecting fetal brain microglial programming could permit screening and intervention. We used lineage tracing to demonstrate the shared ontogeny between fetal brain macrophages (microglia) and fetal placental macrophages (Hofbauer cells) in a mouse model of maternal diet-induced obesity, and single-cell RNA-seq to demonstrate shared transcriptional programs. Comparison with human datasets demonstrated conservation of placental resident macrophage signatures between mice and humans. Single-cell RNA-seq identified common alterations in fetal microglial and Hofbauer cell gene expression induced by maternal obesity, as well as sex differences in these alterations. We propose that Hofbauer cells, which are easily accessible at birth, provide novel insights into fetal brain microglial programs, and may facilitate the early identification of offspring vulnerable to neurodevelopmental disorders in the setting of maternal exposures.

Microbiome analysis of circulating bacterial extracellular vesicles in obsessive-compulsive disorder

AIM

The present study examined the microbiome abundance and composition of drug-naive or drug-free patients with obsessive-compulsive disorder (OCD) compared with healthy controls. In addition, in the OCD group, the microbiome composition was compared between early-onset and late-onset OCD.

METHODS

Serum samples were collected from 89 patients with OCD and 107 age- and sex-matched healthy controls. Bacterial DNA was isolated from bacteria-derived extracellular vesicles in serum and then amplified and quantified using primers specific to the V3-V4 hypervariable region of the 16S ribosomal RNA gene. The 16S ribosomal DNA gene amplicon sequencing was performed.

RESULTS

The pooled estimate showed that α-diversity was significantly reduced in patients with OCD compared with that in healthy controls (PShannon  = 0.00015). In addition, a statistically significant difference was observed in β-diversity between patients with OCD and healthy controls at the order (P = 0.012), family (P = 0.003), genus (P < 0.001), and species (P = 0.005) levels. In the microbiome composition, Pseudomonas, Caulobacteraceae (f), Streptococcus, Novosphingobium, and Enhydrobacter at the genus level were significantly less prevalent in patients with OCD than in controls. In addition, among patients with OCD, the microbial composition in the early-onset versus late-onset types was significantly different with respect to the genera Corynebacterium and Pelomonas.

CONCLUSION

The present study showed an aberrant microbiome in patients with OCD, suggesting a role of the microbiota-brain interaction in the pathophysiology of OCD. Further longitudinal studies with larger sample sizes adjusting for various confounders are warranted.

Tourette syndrome and obsessive-compulsive disorder: A comprehensive review of structural alterations and neurological mechanisms

Currently, it is possible to study the pathogenesis of Tourette's syndrome (TS) in more detail, due to more advanced methods of neuroimaging. However, medical and surgical treatment options are limited by a lack of understanding of the nature of the disorder and its relationship to some psychiatric disorders, the most common of which is obsessive-compulsive disorder (OCD). It is believed that the origin of chronic tic disorders is based on an imbalance of excitatory and inhibitory influences in the Cortico-Striato-Thalamo-Cortical circuits (CSTC). The main CSTCs involved in the pathological process have been identified by studying structural and neurotransmitter disturbances in the interaction between the cortex and the basal ganglia. A neurotransmitter deficiency in CSTC has been demonstrated by immunohistochemical and genetic methods, but it is still not known whether it arises as a consequence of genetically determined disturbances of neuronal migration during ontogenesis or as a consequence of altered production of proteins involved in neurotransmitter production. The aim of this review is to describe current ideas about the comorbidity of TS with OCD, the involvement of CSTC in the pathogenesis of both disorders and the background of structural and neurotransmitter changes in CSTC that may serve as targets for drug and neuromodulatory treatments.

Clinicopathologic Characteristics of PANDAS in a Young Adult: A Case Report

Pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections (PANDAS) is an acute onset or exacerbation of neuropsychiatric symptoms following a group A streptococcus infection. It is believed to be a result of autoimmune response to streptococcal infection, but there is insufficient evidence to fully support this theory. Although this disease is primarily thought to be a disease of childhood, it is reported to occur also in adults. PANDAS is a well-defined clinical entity, but the neuropathology of this condition has not been established yet. We describe the clinical course of a 26-year-old female diagnosed with PANDAS. She committed suicide and her brain was biobanked for further studies. We examined the banked tissue and performed special stains, immunohistochemical, and immunofluorescence analyses to characterize the neuropathology of this condition. Histology of the temporal lobes, hippocampus, and basal ganglia shows mild gliosis and Alzheimer's type II astrocytes. Acute hypoxic ischemic changes were noted in hippocampus CA1 and CA2 areas. Immunostaining shows increased parenchymal/perivascular GFAP staining and many vessels with mild increases in CD3-, CD4-, and CD25-stained lymphocytes in the basal ganglia. The findings suggest that CD4- and CD25-positive T cells might have an important role in understanding the neuroinflammation and pathogenesis of this condition. The case represents the first neuropathological evaluation report for PANDAS.

The Dysfunctional Mechanisms Throwing Tics: Structural and Functional Changes in Tourette Syndrome

Tourette Syndrome (TS) is a high-incidence multifactorial neuropsychiatric disorder characterized by motor and vocal tics co-occurring with several diverse comorbidities, including obsessive-compulsive disorder and attention-deficit hyperactivity disorder. The origin of TS is multifactorial, with strong genetic, perinatal, and immunological influences. Although almost all neurotransmettitorial systems have been implicated in TS pathophysiology, a comprehensive neurophysiological model explaining the dynamics of expression and inhibition of tics is still lacking. The genesis and maintenance of motor and non-motor aspects of TS are thought to arise from functional and/or structural modifications of the basal ganglia and related circuitry. This complex wiring involves several cortical and subcortical structures whose concerted activity controls the selection of the most appropriate reflexive and habitual motor, cognitive and emotional actions. Importantly, striatal circuits exhibit bidirectional forms of synaptic plasticity that differ in many respects from hippocampal and neocortical plasticity, including sensitivity to metaplastic molecules such as dopamine. Here, we review the available evidence about structural and functional anomalies in neural circuits which have been found in TS patients. Finally, considering what is known in the field of striatal plasticity, we discuss the role of exuberant plasticity in TS, including the prospect of future pharmacological and neuromodulation avenues.

Microbial Reprogramming in Obsessive-Compulsive Disorders: A Review of Gut-Brain Communication and Emerging Evidence

Obsessive-compulsive disorder (OCD) is a debilitating mental health disorder characterized by intrusive thoughts (obsessions) and repetitive behaviors (compulsions). Dysbiosis, an imbalance in the gut microbial composition, has been associated with various health conditions, including mental health disorders, autism, and inflammatory diseases. While the exact mechanisms underlying OCD remain unclear, this review presents a growing body of evidence suggesting a potential link between dysbiosis and the multifaceted etiology of OCD, interacting with genetic, neurobiological, immunological, and environmental factors. This review highlights the emerging evidence implicating the gut microbiota in the pathophysiology of OCD and its potential as a target for novel therapeutic approaches. We propose a model that positions dysbiosis as the central unifying element in the neurochemical, immunological, genetic, and environmental factors leading to OCD. The potential and challenges of microbial reprogramming strategies, such as probiotics and fecal transplants in OCD therapeutics, are discussed. This review raises awareness of the importance of adopting a holistic approach that considers the interplay between the gut and the brain to develop interventions that account for the multifaceted nature of OCD and contribute to the advancement of more personalized approaches.

Obsessive-Compulsive Disorder, PANDAS, and Tourette Syndrome: Immuno-inflammatory Disorders

In the last years, much focus has been given to the possible role of inflammatory and immunologic alterations in the pathophysiology of obsessive-compulsive disorder (OCD) and some related conditions, such as pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS) and Tourette syndrome (TS). Although the matter is intriguing, the available data are still controversial and/or limited. Therefore, the aim of this chapter was at reviewing and commenting on the literature on possible dysfunctions of inflammatory and immune system processes in OCD, PANDAS, and TS.This narrative review was carried out through searching PubMed and Google Scholar for English language papers from January 1985 to December 31, 2021.The data gathered up to now would suggest that the mechanisms involved might be heterogeneous according to the age of the patients and the disorder examined. Indeed, PANDAS seem more related to infections triggering autoimmunity not necessarily following group A beta-hemolytic streptococcal (GABHS) infection, as supposed in the past. Autoimmunity seems also important in TS, if coupled with an individual vulnerability that can be genetic and/or environmental. The data in adult OCD, albeit scattered and sometimes obtained in small samples of patients, would indicate that immune system and inflammatory processes are involved in the pathophysiology of the disorder. However, it is still unclear to conclude whether they are primary or secondary phenomena.In conclusion, taken together, the current findings pave that way towards novel and promising domains to explore the pathophysiology of OCD and related disorders, as well towards the development of innovative therapeutic strategy beyond current pharmacological paradigms.

The inflammatory injury in the striatal microglia-dopaminergic-neuron crosstalk involved in Tourette syndrome development

Background

Tourette syndrome (TS) is associated with immunological dysfunction. The DA system is closely related to TS development, or behavioral stereotypes. Previous evidence suggested that hyper-M1-polarized microglia may exist in the brains of TS individuals. However, the role of microglia in TS and their interaction with dopaminergic neurons is unclear. In this study, we applied iminodipropionitrile (IDPN) to establish a TS model and focused on the inflammatory injury in the striatal microglia-dopaminergic-neuron crosstalk.

Methods

Male Sprague-Dawley rats were intraperitoneally injected with IDPN for seven consecutive days. Stereotypic behavior was observed to verify the TS model. Striatal microglia activation was evaluated based on different markers and expressions of inflammatory factors. The striatal dopaminergic neurons were purified and co-cultured with different microglia groups, and dopamine-associated markers were assessed.

Results

First, there was pathological damage to striatal dopaminergic neurons in TS rats, as indicated by decreased expression of TH, DAT, and PITX3. Next, the TS group showed a trend of increased Iba-1 positive cells and elevated levels of inflammatory factors TNF-α and IL-6, as well as an enhanced M1-polarization marker (iNOS) and an attenuated M2-polarization marker (Arg-1). Finally, in the co-culture experiment, IL-4-treated microglia could upregulate the expression of TH, DAT, and PITX3 in striatal dopaminergic neurons vs LPS-treated microglia. Similarly, the TS group (microglia from TS rats) caused a decreased expression of TH, DAT, and PITX3 compared with the Sham group (microglia from control rats) in the dopaminergic neurons.

Conclusion

In the striatum of TS rats, microglia activation is M1 hyperpolarized, which transmits inflammatory injury to striatal dopaminergic neurons and disrupts normal dopamine signaling.

Pediatric neuropsychiatric disorders with motor and nonmotor phenomena

The concept of pediatric autoimmune neuropsychiatric disorders associated with group A beta-hemolytic streptococcus (PANDAS) has become seminal since first introduced more than two decades ago. At the time of this writing, most neurologists, pediatricians, psychiatrists, and general pediatricians will probably have heard of this association or treated an affected child with PANDAS. The concept of an acute-onset, and typically self-limited, postinfectious autoimmune neuropsychiatric disorder resembling PANDAS manifesting vocal and motor tics and obsessive-compulsive disorder has broadened to other putative microbes and related endogenous and exogenous disease triggers. These disorders with common features of hypometabolism in the medial temporal lobe and hippocampus in brain 18fluorodeoxyglucose positron emission tomography fused to magnetic resonance imaging (FDG PET-MRI), form a spectrum: with the neuropsychiatric disorder Tourette syndrome and PANDAS with its well-defined etiopathogenesis at one end, and pediatric abrupt-onset neuropsychiatric syndrome (PANS), alone or associated with specific bacterial and viral pathogens, at the other end. The designation of PANS in the absence of a specific trigger, as an exclusionary diagnosis, reflects the current problem in nosology.

Big data analytics frameworks for the influence of gut microbiota on the development of tic disorder

The association between gut microbiota and psychiatric disorders has received increasing research attention. Meanwhile, big data analysis has been utilized in many filed including business, human healthcare analysis, etc. The primary objective of this article was to provide insights into Big Data Analytics (BDA) to clarify the association between gut microbiota and TD (Tic disorder). Specifically, we investigated the recent studies related to gut microbiota composition differences in patients with TD compared to health people. We searched on PubMed and Embase (Ovid) databases for relevant published articles until June 15, 2021. A total of 78 TD and 62 health control stool samples were examined. Case-control design was applied in all the studies. No consensus was evident in α-diversity and β-diversity. The abundance of phyla Bacteroidetes and Firmicutes was predominant at the taxa level. Gut microbiota taxonomic differences were found between TD cases and controls, though inconsistently across studies. Further studies are needed to reveal the underlying pathophysiology of TD and correlation between TD and gut microbiota composition.

Convergent neural correlates of prenatal exposure to air pollution and behavioral phenotypes of risk for internalizing and externalizing problems: Potential biological and cognitive pathways

Humans are ubiquitously exposed to neurotoxicants in air pollution, causing increased risk for psychiatric outcomes. Effects of prenatal exposure to air pollution on early emerging behavioral phenotypes that increase risk of psychopathology remain understudied. We review animal models that represent analogues of human behavioral phenotypes that are risk markers for internalizing and externalizing problems (behavioral inhibition, behavioral exuberance, irritability), and identify commonalities among the neural mechanisms underlying these behavioral phenotypes and the neural targets of three types of air pollutants (polycyclic aromatic hydrocarbons, traffic-related air pollutants, fine particulate matter < 2.5 µm). We conclude that prenatal exposure to air pollutants increases risk for behavioral inhibition and irritability through distinct mechanisms, including altered dopaminergic signaling and hippocampal morphology, neuroinflammation, and decreased brain-derived neurotrophic factor expression. Future studies should investigate these effects in human longitudinal studies incorporating complex exposure measurement methods, neuroimaging, and behavioral characterization of temperament phenotypes and neurocognitive processing to facilitate efforts aimed at improving long-lasting developmental benefits for children, particularly those living in areas with high levels of exposure.

Profiles of Proinflammatory Cytokines and T Cells in Patients With Tourette Syndrome: A Meta-Analysis

Background

Tic disorder is a neurodevelopmental disorder characterized by motor and phonic tic symptoms. Tourette syndrome (TS) is a subtype of tic disorder that shows more persistent tic symptoms. The etiological mechanism of TS concerning immune dysfunction remains unclear due to limited evidence, especially for pediatric TS patients.

Method

In the present study, a meta-analysis was performed to confirm the identified changes in proinflammatory cytokines and T cells of pediatric TS patients. A total of five databases, including PubMed, Web of Science, PsycINFO, Google Scholar and the China National Knowledge Infrastructure (CNKI), were used for the literature search. The standardized mean difference (SMD) and mean difference (MD) with a 95% confidence interval (CI) were used to present the effect size of each type of proinflammatory cytokine and T cell. Sensitivity analysis, subgroup analysis and meta-regression analysis were used to explore the heterogeneity of the meta-analysis. This meta-analysis was registered in the International Platform of Registered Systematic Review and Meta-analysis Protocols (number: INPLASY2021110079).

Results

In the 25 studies included in this meta-analysis, thirteen studies focused on the levels of T cells, and twelve studies focused on the levels of proinflammatory cytokines. Based on the random-effects model, the pooled MDs are -1.45 (95% CI: -3.44, 0.54) for CD3 cells, -4.44 (95% CI: -6.80, -2.08) for CD4 cells, and 1.94 (95% CI: -0.08, 3.97) for CD8 cells. The pooled SMDs are1.36 for IL-6 (95% CI: 0.00, 2.72) and 2.39 for tumor necrosis factor alpha (TNF-α) (95% CI: 0.93, 3.84).

Conclusion

We provided evidence of immune dysfunction in pediatric TS patients, with elevated levels of particular proinflammatory cytokines and disproportionate changes in T-cell subpopulations. Small to large effect sizes were identified for increased IL-6 levels as well as a reduced number of T helper cells, while a large effect size was identified for increased TNF-α levels. These results indicate a close association between peripheral immune activation and TS. However, the most direct and meaningful interaction between peripheral immune status and microglial activation in the central nervous system in TS patients requires further exploration.

Children With PANS May Manifest POTS

Objectives

Pediatric acute-onset neuropsychiatric syndrome (PANS) is characterized by an abrupt-onset of severe psychiatric symptoms including OCD, anxiety, cognitive difficulties, and sleep issues which is thought to be a post-infection brain inflammatory disorder. We observed postural orthostatic tachycardia syndrome (POTS) which resolved with immunomodulation in a patient with Pediatric acute-onset neuropsychiatric syndrome (PANS). Here, we aim to present a case of POTS and to examine the prevalence of (POTS) in our PANS cohort, and compare the clinical characteristics of patients with and without POTS.

Study Design

We conducted this cohort study of patients meeting PANS criteria who had at least three clinic visits during the study period. We included data from prospectively collected questionnaires and medical record review. We present a case followed by statistical comparisons within our cohort and a Kaplan-Meier analysis to determine the time-dependent risk of a POTS diagnosis.

Results

Our study included 204 patients: mean age of PANS onset was 8.6 years, male sex (60%), non-Hispanic White (78%). Evidence of POTS was observed in 19/204 patients (9%) with 5/19 having persistent POTS defined as persistent abnormal orthostatic vitals, persistent POTS symptoms, and/or continued need for pharmacotherapy for POTS symptoms for at least 6 months). In this PANS cohort, patients with POTS were more likely to have comorbid joint hypermobility (63 vs 37%, p = 0.04), chronic fatigue (42 vs 18%, p = 0.03), and a family history of chronic fatigue, POTS, palpitations and syncope. An unadjusted logistic regression model showed that a PANS flare (abrupt neuropsychiatric deterioration) was significantly associated with an exacerbation of POTS symptoms (OR 3.3, 95% CI 1.4–7.6, p < 0.01).

Conclusions

Our study describes a high prevalence of POTS in patients with PANS (compared to the general population) and supports an association between POTS presentation and PANS flare within our cohort.

Is the Use of Glyphosate in Modern Agriculture Resulting in Increased Neuropsychiatric Conditions Through Modulation of the Gut-brain-microbiome Axis?

Environmental exposure to glyphosate and glyphosate-based herbicides has the potential to negatively influence neurodevelopment and behavior across generations indirectly through the gut-brain-microbiome axis. Potential mechanisms by which glyphosate may elicit these effects are through the disruption of the normally symbiotic relationship of the host and the gut microbiome. Given glyphosate can kill commensal members of the microbiome like Lactobacillus spp., Ruminococaeae and Butyricoccus spp., resulting in reductions in key microbial metabolites that act through the gut-brain-microbiome axis including indoles, L-glutamate and SCFAs. Glyphosate- resistant microbes in the gut have the potential to increase the production of pro-inflammatory cytokines and reactive oxygen species which may result in increased HPA activation, resulting in increased production of glucocorticoids which have implications on neurodevelopment. In addition, maternal transfer of the gut microbiome can affect immune and neurodevelopment, across generations. This perspective article weighs the evidence for chronic glyphosate exposure on the gut microbiome and the potential consequences on the gut-brain axis correlated with increased incidence of neuropsychiatric conditions.

Role of histidine decarboxylase gene in the pathogenesis of Tourette syndrome

Tourette syndrome (TS) is caused by complex genetic and environmental factors and is characterized by tics. Histidine decarboxylase (HDC) mutation is a rare genetic cause with high penetrance in patients with TS. HDC-knockout (KO) mice have similar behavioral and neurochemical abnormalities as patients with TS. Therefore, HDC-KO mice are considered a valuable TS pathophysiological model as it reveals the underlying pathological mechanisms that cannot be obtained from patients with TS, thus advancing the development of treatment strategies for TS and other tic disorders. This review summarizes some of the recent research hotspots and progress in HDC-KO mice, aiming to deepen our understanding of brain mechanisms relevant to TS. Furthermore, we encapsulate the possible brain nerve cell changes in HDC-KO mice and their potential roles in TS to provide multiple directions for the future research on tics.

Mice lacking 5-lipoxygenase display motor deficits associated with cortical and hippocampal synapse abnormalities

Neural-immune interactions are related to the synapse plasticity and other dynamic processes in the nervous system. The absence or dysfunction of cellular/molecular elements from the immune system lead to impairments in the central and peripheral nervous system with behavior consequences such as cognitive, sensory, and locomotor deficits as well as social disabilities and anxiety disturbances. Cellular interactions between immune cells such as macrophages, microglia, and neutrophils with glial or neuronal cells have been of increasing interest over the last years. However, little is known about the role of immune-derived soluble factors in the context of homeostasis of the nervous system. Leukotrienes (LTs) are lipid mediators derived from the oxidation of arachidonic acid by 5-lipoxygenase (5-LO), and are classically involved in inflammation, allergies, and asthma. Here, we demonstrated that adult mice lacking 5-LO (5-LO^-/-) showed motor deficits in rotarod test and increased repetitive behavior (marble burying test). These behavioral changes are accompanied by increased levels of synapse proteins (PSD95 and synaptophysin) at the motor cortex and hippocampus, but not with BDNF alterations. No changes in microglial cell density or morphology were seen in the brains of 5-LO^-/- mice. Furthermore, expression of fractalkine receptor CX3CR1 was increased and of its ligand CX3CL1 was decreased in the cortex of 5-LO^-/- mice. Here we provide evidence for the involvement of 5-LO products structuring synapses network with motor behavior consequences. We suggest that the absence of 5-LO products lead to modified microglial/neuron interaction, reducing microglial pruning.

Dopamine-2 receptor antibody encephalitis presenting as pure tongue-biting in a tourette syndrome patient: a case report

BACKGROUND

Tourette syndrome (TS) is a neuropsychiatric disorder characterized by repetitive and patterned tics. Its onset correlates with dysfunctions in immunological activation and neurotransmitters. Autoimmune movement disorders such as dopamine-2 receptor antibody encephalitis (D2R encephalitis) may go undiagnosed in TS patients seeking medical help for tic symptoms only. Here, we present a clinical case of D2R encephalitis in a TS patient.

CASE PRESENTATION

A 13-year-old boy with a history of TS presented with acute tongue-biting without positive neurologic examination or auxiliary examination results, except for a weakly positive finding for D2R antibodies in the serum sample. He was initially diagnosed with possible D2R encephalitis, but the influence of TS could not be ruled out. In addition to psychotropics, we administered immunotherapy early based on clinical characteristics, and his symptoms were ameliorated significantly. During the follow-up, he was diagnosed with definite D2R encephalitis, and the dosage of psychotropics was further adjusted for fluctuating symptoms.

CONCLUSIONS

Our case suggests that clinicians should discern D2R encephalitis in TS patients when tics are the primary symptoms. Administering immunotherapy early, according to clinical characteristics, may benefit the patient. Moreover, the features of premonitory urges could help evaluate the state of TS.

Elevated serum S100B levels in medication naïve children and adolescents with obsessive-compulsive disorder

PURPOSE

Obsessive-compulsive disorder (OCD) is a condition characterized by obsessions and/or compulsions. S100B protein is shown to be involved in microglial activation besides intracellular signaling, intercellular communication and cell growth. The relation between S100B protein and various psychiatric disorders except OCD has been studied so far. This study aimed to analyze serum S100B levels for the first time in medication naive OCD diagnosed children and adolescents and to compare them with the control group.

MATERIALS AND METHODS

Peripheral blood S100B levels of 27 children and adolescents with OCD were compared to 27 control group subjects to assess any possible association between OCD and S100B levels. All the children and adolescents completed the child version of the Obsessive-Compulsive Inventory (OCI - CV).

RESULTS

Compared to control group, higher serum S100B levels were found in OCD group (z = -2.258, p = 0.024). We also found that obsessing and washing subscales' scores and total score of OCI - CV were statistically significantly correlated with S100B levels (respectively, r = .292, p = 0.032; r = .306, p = 0.025; r = .296, p = 0.030).

CONCLUSIONS

The present study's findings are in accord with previous studies demonstrating the significance of S100B protein in other psychiatric disorders and suggesting a relation in children and adolescents with OCD for the first time. The role of S100B protein in OCD etiology and pathogenesis should be evaluated further.

Depicting the composition of gut microbiota in children with tic disorders: an exploratory study

BACKGROUND

Symptom improvement in children with tic disorder (TD) following fecal microbiota transplantation led us to investigate the gut microbiota in TD. This exploratory study aims to depict the gut microbial profile in patients with TD and explore the impact of dopamine receptor antagonist (DRA) drugs on the composition and metabolic function of the gut microbiota.

METHODS

The gut microbiota were profiled in fecal samples of 49 children with TD and 50 matched healthy controls (HC) using shotgun metagenomic sequencing. A random forest (RF) model was constructed using the gut bacterial species to distinguish TD from HC. Associations between clinical metadata and microbial abundance or function were analyzed using MaAsLin2 and Spearman correlation.

RESULTS

The gut microbiota in children with TD was featured by higher abundances of Bacteroides plebeius and Ruminococcus lactaris (a potential pro-inflammatory taxon) and lower abundances of Prevotella stercorea and Streptococcus lutetiensis compared to HC. The constructed RF model accurately distinguished TD from HC based on the gut microbiota profile, resulting in an AUC of 0.884. Significant correlations were observed between tic symptom severity and the abundances of multiple bacterial species and gut microbiota metabolic functions. Multivariate analysis identified an upregulation of 4-aminobutanoate (GABA) degradation in the gut microbiota associated with TD status. The gut microbiota of DRA-treated TD children showed a distinct gut microbiota compared to the treatment-naïve group, represented by an increase in some potential enteric pathogens such as Escherichia coli, a decline in several species including Akkermansia muciniphila, and alterations in various metabolic functions.

CONCLUSIONS

Bacterial species promoting inflammatory responses and those modulating neurotransmitters such as GABA may be involved in the pathogenesis of TD. The use of DRA drugs is likely to induce overgrowth of some enteric pathogens and alter the gut microbiota metabolism.

Candidate Genes and Pathways Associated with Gilles de la Tourette Syndrome-Where Are We?

Gilles de la Tourette syndrome (GTS) is a childhood-onset neurodevelopmental and -psychiatric tic-disorder of complex etiology which is often comorbid with obsessive-compulsive disorder (OCD) and/or attention deficit hyperactivity disorder (ADHD). Twin and family studies of GTS individuals have shown a high level of heritability suggesting, that genetic risk factors play an important role in disease etiology. However, the identification of major GTS susceptibility genes has been challenging, presumably due to the complex interplay between several genetic factors and environmental influences, low penetrance of each individual factor, genetic diversity in populations, and the presence of comorbid disorders. To understand the genetic components of GTS etiopathology, we conducted an extensive review of the literature, compiling the candidate susceptibility genes identified through various genetic approaches. Even though several strong candidate genes have hitherto been identified, none of these have turned out to be major susceptibility genes yet.

Inflammatory neuropsychiatric disorders and COVID-19 neuroinflammation

Neuropsychiatric sequalae to coronavirus disease 2019 (COVID-19) infection are beginning to emerge, like previous Spanish influenza and severe acute respiratory syndrome episodes. Streptococcal infection in paediatric patients causing obsessive compulsive disorder (PANDAS) is another recent example of an infection-based psychiatric disorder. Inflammation associated with neuropsychiatric disorders has been previously reported but there is no standard clinical management approach established. Part of the reason is that it is unclear what factors determine the specific neuronal vulnerability and the efficacy of anti-inflammatory treatment in neuroinflammation. The emerging COVID-19 data suggested that in the acute stage, widespread neuronal damage appears to be the result of abnormal and overactive immune responses and cytokine storm is associated with poor prognosis. It is still too early to know if there are long-term-specific neuronal or brain regional damages associated with COVID-19, resulting in distinct neuropsychiatric disorders. In several major psychiatric disorders where neuroinflammation is present, patients with abnormal inflammatory markers may also experience less than favourable response or treatment resistance when standard treatment is used alone. Evidence regarding the benefits of co-administered anti-inflammatory agents such as COX-2 inhibitor is encouraging in selected patients though may not benefit others. Disease-modifying therapies are increasingly being applied to neuropsychiatric diseases characterised by abnormal or hyperreactive immune responses. Adjunct anti-inflammatory treatment may benefit selected patients and is definitely an important component of clinical management in the presence of neuroinflammation.

Maternal allergic inflammation in rats impacts the offspring perinatal neuroimmune milieu and the development of social play, locomotor behavior, and cognitive flexibility

Maternal systemic inflammation increases risk for neurodevelopmental disorders like autism, ADHD, and schizophrenia in offspring. Notably, these disorders are male-biased. Studies have implicated immune system dysfunction in the etiology of these disorders, and rodent models of maternal immune activation provide useful tools to examine mechanisms of sex-dependent effects on brain development, immunity, and behavior. Here, we employed an allergen-induced model of maternal inflammation in rats to characterize levels of mast cells and microglia in the perinatal period in male and female offspring, as well as social, emotional, and cognitive behaviors throughout the lifespan. Adult female rats were sensitized to ovalbumin (OVA), bred, and challenged intranasally on gestational day 15 of pregnancy with OVA or saline. Allergic inflammation upregulated microglia in the fetal brain, increased mast cell number in the hippocampus on the day of birth, and conferred region-, time- and sex- specific changes in microglia measures. Additionally, offspring of OVA-exposed mothers subsequently exhibited abnormal social behavior, hyperlocomotion, and reduced cognitive flexibility. These data demonstrate the long-term effects of maternal allergic challenge on offspring development and provide a basis for understanding neurodevelopmental disorders linked to maternal systemic inflammation in humans.

Maternal autoimmunity and inflammation are associated with childhood tics and obsessive-compulsive disorder: Transcriptomic data show common enriched innate immune pathways

Although genetic variation is a major risk factor of neurodevelopmental disorders, environmental factors during pregnancy and early life are also important in disease expression. Animal models demonstrate that maternal inflammation causes fetal neuroinflammation and neurodevelopmental deficits, and brain transcriptomics of neurodevelopmental disorders in humans show upregulated differentially expressed genes are enriched in immune pathways. We prospectively recruited 200 sequentially referred children with tic disorders/obsessive-compulsive disorder (OCD), 100 autoimmune neurological controls, and 100 age-matched healthy controls. A structured interview captured the maternal and family history of autoimmune disease and other pro-inflammatory states. Maternal blood and published Tourette brain transcriptomes were analysed for overlapping enriched pathways. Mothers of children with tics/OCD had a higher rate of autoimmune disease compared with mothers of children with autoimmune neurological conditions (p = 0.054), and mothers of healthy controls (p = 0.0004). Autoimmunity was similarly elevated in first- and second-degree maternal relatives of children with tics/OCD (p < 0.0001 and p = 0.014 respectively). Other pro-inflammatory states were also more common in mothers of children with tics/OCD than controls (p < 0.0001). Upregulated differentially expressed genes in maternal autoimmune disease and Tourette brain transcriptomes were commonly enriched in innate immune processes. Pro-inflammatory states, including autoimmune disease, are more common in the mothers and families of children with tics/OCD. Exploratory transcriptome analysis indicates innate immune signalling may link maternal inflammation and childhood tics/OCD. Targeting inflammation may represent preventative strategies in pregnancy and treatment opportunities for children with neurodevelopmental disorders.

Hypoferritinemia and iron deficiency in youth with pediatric acute-onset neuropsychiatric syndrome

BACKGROUND

Pediatric acute-onset neuropsychiatric syndrome (PANS) is an abrupt debilitating psychiatric illness. We anecdotally observed hypoferritinemia and iron deficiency in a subset of patients with PANS, prompting this study.

METHODS

In this IRB-approved prospective cohort study, we included patients seen at the Stanford PANS Clinic who met study criteria. The prevalence of hypoferritinemia (using cut-offs of 7 ng/ml in children ≤ 15 years and 18 ng/ml in adolescents > 15 years) and iron deficiency was estimated. Differences in patients with and without hypoferritinemia during PANS flare were explored.

RESULTS

Seventy-nine subjects (mean age of PANS onset of 8.7 years) met study criteria. Hypoferritinemia was observed in 27% and three quarters occurred during a PANS flare. Compared to patients without hypoferritinemia during PANS flare, patients with hypoferritinemia had worse global impairment, more comorbid inflammatory diseases, and exhibited a chronic course of PANS illness. The estimated prevalence of iron deficiency was 3-8% in the PANS cohort, 1.4-2.0-fold higher than in the age- and sex-matched U.S.

POPULATION

More stringent ferritin level cut-offs than the comparison CDC dataset were used.

CONCLUSION

Hypoferritinemia and iron deficiency appear to be more common in PANS patients. More research is needed to confirm and understand this association.

IMPACT

Our study suggests hypoferritinemia and iron deficiency are more common in patients with pediatric acute-onset neuropsychiatric syndrome (PANS) than in the sex- and age-matched US population. Hypoferritinemia was commonly observed during a disease flare but not associated with dietary or demographic factors. In patients with PANS and iron deficiency, clinicians should consider possibility of inflammation as the cause especially if iron deficiency cannot be explained by diet and blood loss. Future research should include larger cohorts to corroborate our study findings and consider examining the iron dynamics on MRI brain imaging in order to better understand the pathophysiology of PANS.

Neuro-Immune Cross-Talk in the Striatum: From Basal Ganglia Physiology to Circuit Dysfunction

The basal ganglia network is represented by an interconnected group of subcortical nuclei traditionally thought to play a crucial role in motor learning and movement execution. During the last decades, knowledge about basal ganglia physiology significantly evolved and this network is now considered as a key regulator of important cognitive and emotional processes. Accordingly, the disruption of basal ganglia network dynamics represents a crucial pathogenic factor in many neurological and psychiatric disorders. The striatum is the input station of the circuit. Thanks to the synaptic properties of striatal medium spiny neurons (MSNs) and their ability to express synaptic plasticity, the striatum exerts a fundamental integrative and filtering role in the basal ganglia network, influencing the functional output of the whole circuit. Although it is currently established that the immune system is able to regulate neuronal transmission and plasticity in specific cortical areas, the role played by immune molecules and immune/glial cells in the modulation of intra-striatal connections and basal ganglia activity still needs to be clarified. In this manuscript, we review the available evidence of immune-based regulation of synaptic activity in the striatum, also discussing how an abnormal immune activation in this region could be involved in the pathogenesis of inflammatory and degenerative central nervous system (CNS) diseases.

Evaluation of Intravenous Immunoglobulin in Pediatric Acute-Onset Neuropsychiatric Syndrome

Objectives: Pediatric acute-onset neuropsychiatric syndrome (PANS) is a clinical diagnosis in children who have an acute manifestation of varied neuropsychiatric symptoms, including obsessive compulsive disorder, eating disorders, tics, anxiety, irritability, and problems with attention/concentration. PANS may develop as a result of a postinfectious syndrome and may represent a new form of postinfectious autoimmunity. To test the hypothesis that multiple, consecutive infusions of intravenous immunoglobulin (IVIG) for PANS can be efficacious, a multisite, open-label study was designed. Methods: The primary endpoint was evaluation of the efficacy of IVIG [Octagam 5%] in PANS over a period of 6 months (six infusions) based on mean changes in psychological evaluation scores using 6 different assessments, including the Children's Yale-Brown Obsessive Compulsive Scale (CY-BOCS), Clinical Global Impression of Severity, and the Parent-Rated Pediatric Acute Neuropsychiatric Symptom Scale (PANS Scale). Results: The final cohort consisted of 21 subjects (7 per site) with moderate to severe PANS. The mean age was 10.86 years (range: 4-16 years). Results demonstrated statistically significant reductions in symptoms from baseline to end of treatment in all six assessments measured. CY-BOCS results demonstrated statistically significant reductions in obsessive compulsive symptoms (p < 0.0001), resulting in >50% improvement sustained for at least 8 weeks after the final infusion and up to 46 weeks in a subset of subjects. Conclusions: In PANS, which may be associated with an underlying immune dysregulation, sequential infusions of IVIG [Octagam 5%] successfully ameliorated psychological symptoms and dysfunction, with sustained benefits for at least 8 weeks, and up to 46 weeks in a subset of subjects. In addition, baseline immune and autoimmune profiles demonstrated significant elevations in a majority of subjects, which requires further evaluation, characterization, and study to clarify the potential immune dysfunction by which PANS manifests and progresses.

Searching for host immune-microbiome mechanisms in obsessive-compulsive disorder: A narrative literature review and future directions

Obsessive-compulsive disorder (OCD) is disabling and often treatment-refractory. Host immunity and gut microbiota have bidirectional communication with each other and with the brain. Perturbations to this axis have been implicated in neuropsychiatric disorders, but immune-microbiome signaling in OCD is relatively underexplored. We review support for further pursuing such investigations in OCD, including: 1) gut microbiota has been associated with OCD, but causal pathogenic mechanisms remain unclear; 2) early environmental risk factors for OCD overlap with critical periods of immune-microbiome development; 3) OCD is associated with increased risk of immune-mediated disorders and changes in immune parameters, which are separately associated with the microbiome; and 4) gut microbiome manipulations in animal models are associated with changes in immunity and some obsessive-compulsive symptoms. Theoretical pathogenic mechanisms could include microbiota programming of cytokine production, promotion of expansion and trafficking of peripheral immune cells to the CNS, and regulation of microglial function. Immune-microbiome signaling in OCD requires further exploration, and may offer novel insights into pathogenic mechanisms and potential treatment targets for this disabling disorder.

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.

Sapap3 deletion causes dynamic synaptic density abnormalities: a longitudinal [11C]UCB-J PET study in a model of obsessive-compulsive disorder-like behaviour

Background

Currently, the evidence on synaptic abnormalities in neuropsychiatric disorders—including obsessive–compulsive disorder (OCD)—is emerging. The newly established positron emission tomography (PET) ligand ((R)-1-((3-((11)C-methyl-(11)C)pyridin-4-yl)methyl)-4-(3,4,5-trifluorophenyl)pyrrolidin-2-one) ([¹¹C]UCB-J) provides the opportunity to visualize synaptic density changes in vivo, by targeting the synaptic vesicle protein 2A (SV2A). Here, we aim to evaluate such alterations in the brain of the SAP90/PSD-95-associated protein 3 (Sapap3) knockout (ko) mouse model, showing an abnormal corticostriatal neurotransmission resulting in OCD-like behaviour.

Methods

Longitudinal [¹¹C]UCB-J µPET/CT scans were acquired in Sapap3 ko and wildtype (wt) control mice (n = 9/group) to study SV2A availability. Based on the Logan reference method, we calculated the volume of distribution (V_T(IDIF)) for [¹¹C]UCB-J. Both cross-sectional (wt vs. ko) and longitudinal (3 vs. 9 months) volume-of-interest-based statistical analysis and voxel-based statistical parametric mapping were performed. Both [¹¹C]UCB-J ex vivo autoradiography and [³H]UCB-J in vitro autoradiography were used for the validation of the µPET data.

Results

At the age of 3 months, Sapap3 ko mice are already characterized by a significantly lower SV2A availability compared to wt littermates (i.a. cortex − 12.69%, p < 0.01; striatum − 14.12%, p < 0.001, thalamus − 13.11%, p < 0.001, and hippocampus − 12.99%, p < 0.001). Healthy ageing in control mice was associated with a diffuse and significant (p < 0.001) decline throughout the brain, whereas in Sapap3 ko mice this decline was more confined to the corticostriatal level. A strong linear relationship (p < 0.0001) was established between the outcome parameters of [¹¹C]UCB-J µPET and [¹¹C]UCB-J ex vivo autoradiography, while such relationship was absent for [³H]UCB-J in vitro autoradiography.

Conclusions

[¹¹C]UCB-J PET is a potential marker for synaptic density deficits in the Sapap3 ko mouse model for OCD, parallel to disease progression. Our data suggest that [¹¹C]UCB-J ex vivo autoradiography is a suitable proxy for [¹¹C]UCB-J PET data in mice.

The Psychopharmacology of Obsessive-Compulsive Disorder: A Preclinical Roadmap

This review evaluates current knowledge about obsessive-compulsive disorder (OCD), with the goal of providing a roadmap for future directions in research on the psychopharmacology of the disorder. It first addresses issues in the description and diagnosis of OCD, including the structure, measurement, and appropriate description of the disorder and issues of differential diagnosis. Current pharmacotherapies for OCD are then reviewed, including monotherapy with serotonin reuptake inhibitors and augmentation with antipsychotic medication and with psychologic treatment. Neuromodulatory therapies for OCD are also described, including psychosurgery, deep brain stimulation, and noninvasive brain stimulation. Psychotherapies for OCD are then reviewed, focusing on behavior therapy, including exposure and response prevention and cognitive therapy, and the efficacy of these interventions is discussed, touching on issues such as the timing of sessions, the adjunctive role of pharmacotherapy, and the underlying mechanisms. Next, current research on the neurobiology of OCD is examined, including work probing the role of various neurotransmitters and other endogenous processes and etiology as clues to the neurobiological fault that may underlie OCD. A new perspective on preclinical research is advanced, using the Research Domain Criteria to propose an adaptationist viewpoint that regards OCD as the dysfunction of a normal motivational system. A systems-design approach introduces the security motivation system (SMS) theory of OCD as a framework for research. Finally, a new perspective on psychopharmacological research for OCD is advanced, exploring three approaches: boosting infrastructure facilities of the brain, facilitating psychotherapeutic relearning, and targeting specific pathways of the SMS network to fix deficient SMS shut-down processes. SIGNIFICANCE STATEMENT: A significant proportion of patients with obsessive-compulsive disorder (OCD) do not achieve remission with current treatments, indicating the need for innovations in psychopharmacology for the disorder. OCD may be conceptualized as the dysfunction of a normal, special motivation system that evolved to manage the prospect of potential danger. This perspective, together with a wide-ranging review of the literature, suggests novel directions for psychopharmacological research, including boosting support systems of the brain, facilitating relearning that occurs in psychotherapy, and targeting specific pathways in the brain that provide deficient stopping processes in OCD.

Using multiple measurements of tissue to estimate subject- and cell-type-specific gene expression

Motivation

Patterns of gene expression, quantified at the level of tissue or cells, can inform on etiology of disease. There are now rich resources for tissue-level (bulk) gene expression data, which have been collected from thousands of subjects, and resources involving single-cell RNA-sequencing (scRNA-seq) data are expanding rapidly. The latter yields cell type information, although the data can be noisy and typically are derived from a small number of subjects.

Results

Complementing these approaches, we develop a method to estimate subject- and cell-type-specific (CTS) gene expression from tissue using an empirical Bayes method that borrows information across multiple measurements of the same tissue per subject (e.g. multiple regions of the brain). Analyzing expression data from multiple brain regions from the Genotype-Tissue Expression project (GTEx) reveals CTS expression, which then permits downstream analyses, such as identification of CTS expression Quantitative Trait Loci (eQTL).

Availability and implementation

We implement this method as an R package MIND, hosted on https://github.com/randel/MIND.

Supplementary information

Supplementary data are available at Bioinformatics online.

Regulatory effects of Ningdong granule on microglia-mediated neuroinflammation in a rat model of Tourette's syndrome

Tourette's syndrome (TS) is an inherited neurologic disorder characterized by involuntary stereotyped motor and vocal tics. Its pathogenesis is still unclear and its treatment remains limited. Recent research has suggested the involvement of immune mechanisms in the pathophysiology of TS. Microglia are the brain's resident innate immune cells. They can mediate neuroinflammation and regulate brain development and homeostasis. A traditional Chinese medicine (TCM), Ningdong granule (NDG), has been found to be efficacious in the treatment of TS while causing few adverse reactions. In the current study, a rat model of 3,3'-iminodipropionitrile (IDPN)-induced TS was used to explore the regulating effects and mechanisms of NDG on microglia-mediated neuroinflammation. IDNP led to robust pathological changes and neurobehavioral complications, with activation of microglia in the striatum of rats with TS. After activation by IDNP, microglia strongly responded to this specific injury, and TNF-α, IL-6, and MCP-1 were released in the striatum and/or serum of rats with TS. Interestingly, NDG inhibited the activation of microglia and decreased the abnormal expression of TNF-α, IL-6, and MCP-1 in the striatum and/or serum of rats with TS, thus controlling tics. However, there were no significant changes in the striatum and/or serum of rats with TS after treatment with haloperidol. The anti-TS action of haloperidol might occur not through microglial activation and neuroinflammation but through the DAT system, thus controlling tics. In conclusion, microglia might play key roles in mediating neuroinflammatory responses in TS, triggering the release of TNF-α, IL-6, and MCP-1.NDG inhibited tics in rats with TS, and this mechanism may be associated with a reduction in the increased number of activated microglia and a decrease in the expression of pro-inflammatory cytokines and chemokines in the striatum and/or serum.

Deep slow nasal respiration with tight lip closure for immediate attenuation of severe tics

BACKGROUND

Severe intractable tics, which are associated with Tourette syndrome and chronic tic disorder (TS/CTD), severely affect the quality of life. Common less-invasive treatments are often unable to attenuate tics with deep brain stimulation currently being the only effective treatment. We aimed to assess the anti-tic effect of deep slow nasal respiration with tight lip closure using patients with TS/CTD.

METHODS

We retrospectively analyzed 10 consecutive patients (9 men, 1 woman; 23-41 years old). We instructed the patients to perform the procedure for 120 s and to obtain a video recording of before and during the procedure. The videos were used to count tics and determine lip competency or incompetency. The counted tics were rated using the modified Rush Video Rating Scale.

RESULTS

Compared with before the procedure, there were significantly lower frequencies of motor and phonic tics, as well as video scored, during the procedure. Eight patients presented with lip incompetency before the procedure and none after the procedure (P = 0.041). There were no side effects associated with the procedure.

CONCLUSION

Our findings indicate that deep slow nasal respiration with tight lip closure ameliorates tics in patients with TS/CTD. In accordance with our results, lip opening and oral breathing could be causes of tics, in addition to heritability. Therefore, this novel procedure could improve tics. Furthermore, our findings could contribute toward the development of tic treatments and elucidate their pathophysiology regarding the reward system, hypersensitivity, autonomic nerves, and nasal airway.

Alterations in the Nervous System and Gut Microbiota after β-Hemolytic Streptococcus Group A Infection-Characteristics and Diagnostic Criteria of PANDAS Recognition

The objective of this paper is to review and summarize conclusions from the available literature regarding Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS). The authors have independently reviewed articles from 1977 onwards, primarily focusing on the etiopathology, symptoms, differentiation between similar psychiatric conditions, immunological reactions, alterations in the nervous system and gut microbiota, genetics, and the available treatment for PANDAS. Recent research indicates that PANDAS patients show noticeable alterations within the structures of the central nervous system, including caudate, putamen, globus pallidus, and striatum, as well as bilateral and lentiform nuclei. Likewise, the presence of autoantibodies that interact with basal ganglia was observed in PANDAS patients. Several studies also suggest a relationship between the presence of obsessive-compulsive disorders like PANDAS and alterations to the gut microbiota. Further, genetic predispositions-including variations in the MBL gene and TNF-α-seem to be relevant regarding PANDAS syndrome. Even though the literature is still scarce, the authors have attempted to provide a thorough insight into the PANDAS syndrome, bearing in mind the diagnostic difficulties of this condition.

Tourette's disorder in children and adolescents

Tourette's disorder (TD) is one of the five American Psychiatric Association's 2013 Diagnostic and Statistical Manual of Mental Disorders (DSM-5) classifications of tic disorders. Eponymously linked with the noted 19th century French physician, Gilles de la Tourette [1857-1904], this disorder is identified in 0.3% to 0.7% of the population. It is characterized as a familial neuropsychiatric condition with multiple motor tics and vocal tics (one or more) present for more than 1 year with varying severity. The underlying pathophysiology involves dysfunctional activity of the basal ganglia and circuitry of the frontal cortex as well as dorsolateral striatum deficits. Contributory factors include genetic features interacting with milieu influences. A number of comorbid disorders are seen including obsessive-compulsive disorder (OCD) and attention-deficit/hyperactivity disorder (ADHD). Concepts of management are considered including behavioral therapy and pharmacologic approaches with alpha-adrenoceptor agonists, atypical antipsychotics (AAs), haloperidol, pimozide and others. Other management includes botulinum injections and deep brain stimulation in adults.

Modeling Inflammation on Neurodevelopmental Disorders Using Pluripotent Stem Cells

Neurodevelopmental disorders (ND) are characterized by an impairment of the nervous system during its development, with a wide variety of phenotypes based on genetic or environmental cues. There are currently several disorders grouped under ND including intellectual disabilities (ID), attention-deficit hyperactivity disorder (ADHD), and autism spectrum disorders (ASD). Although NDs can have multiple culprits with varied diagnostics, several NDs present an inflammatory component. Taking advantage of induced pluripotent stem cells (iPSC), several disorders were modeled in a dish complementing in vivo data from rodent models or clinical data. Monogenic syndromes displaying ND are more feasible to be modeled using iPSCs also due to the ability to recruit patients and clinical data available. Some of these genetic disorders are Fragile X Syndrome (FXS), Rett Syndrome (RTT), and Down Syndrome (DS). Environmental NDs can be caused by maternal immune activation (MIA), such as the infection with Zika virus during pregnancy known to cause neural damage to the fetus. Our goal in this chapter is to review the advances of using stem cell research in NDs, focusing on the role of neuroinflammation on ASD and environmental NDs studies.

High-refined carbohydrate diet consumption induces neuroinflammation and anxiety-like behavior in mice

Consumption of poor nutrients diets is associated with fat tissue expansion and with a central and peripheral low-grade inflammation. In this sense, the microglial cells in the central nervous system are activated and release pro-inflammatory cytokines that up-regulate the inducible nitric oxide synthase (iNOS), promoting Nitric Oxide (NO) production. The excess of NO has been proposed to facilitate anxious states in humans and rodents. We evaluated whether consumption of a high-refined carbohydrate-containing diet (HC) in mice induced anxiety-like behavior in the Novelty Suppressed Feeding Test (NFST) trough facilitation of NO, in the prefrontal cortex (PFC) and hippocampus (HIP). We also verified if HC diet induces activation of microglial cells, alterations in cytokine and leptin levels in such regions. Male BALB/c mice received a standard diet or a HC diet for 3 days or 12 weeks. The chronic consumption of HC diet, but not acute, induced an anxiogenic-like effect in the NSF test and an increase in the nitrite levels in the PFC and HIP. The preferential iNOS inhibitor, aminoguanidine (50 mg/kg, i.p.), attenuated such effects. Moreover, microglial cells in the HIP and PFC were activated after chronic consumption of HC diet. Finally, the expression of iNOS in the PFC and TNF, IL6 and leptin levels in HIP were higher in chronically HC fed mice. Taken together, our data reinforce the notion that diets containing high-refined carbohydrate facilitate anxiety-like behavior, mainly after a long period of consumption. The mechanisms involve, at least in part, the augmentation of neuroinflammatory processes in brain areas responsible for anxiety control.

Altered frequencies of Th17 and Treg cells in children and adolescents with obsessive-compulsive disorder

OBJECTIVE

Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric disorder with an etiopathophysiology that seems to include immune alterations. Previous studies have suggested that variations in the levels of circulating T cell subpopulations may be involved in psychiatric diseases. However, the role of these cells in OCD remains unexplored. Hence, the present study aimed to examine the levels of T helper 1 (Th1), Th2, Th17 and regulatory T (Treg) cells in patients with early-onset OCD and healthy controls.

METHODS

The assessment was performed in 99 children and adolescents with OCD and 46 control subjects. The percentages of circulating Th1, Th2, Th17 and Treg cells were evaluated using flow cytometry.

RESULTS

OCD patients had significantly higher levels of Th17 cells and lower percentages of Treg cells than healthy controls (p = 0.001 and p = 0.005, respectively). Furthermore, levels of Th17 cells progressively increased with the duration (p = 0.005) and severity of OCD (p = 0.008), whereas the percentages of Treg cells significantly declined with the duration of the disorder (p = 1.8 × 10^-5).

CONCLUSIONS

These results provide more evidence of the involvement of immune dysregulation, specifically an imbalance in the levels of circulating T helper and regulatory T cells, in the pathophysiology of early-onset OCD.

Antibodies to neuronal surface proteins in Tourette Syndrome: Lack of evidence in a European paediatric cohort

In Tourette Syndrome (TS) a role for autoantibodies directed against neuronal proteins has long been suspected, but so far results are still inconsistent. The aim of this study was to look for antibodies to specific or undefined neuronal proteins that could be involved in the aetiology of the disease. Sera from children with Tourette Syndrome or another chronic tic disorder (TS/TD), collected as part of the longitudinal European Multicenter Tics in Children Study, were investigated. Participants included 30 siblings of patients with TS/TD prior to developing tics (preclinical stage) and the same children after the first tic onset (onset), and 158 patients in the chronic phase undergoing an acute relapse (exacerbation). Presence of antibodies binding to rodent brain tissue was assessed by immunohistology on rat brain sections and by immunofluorescent staining of live hippocampal neurons. Live cell-based assays were used to screen for antibodies to NMDAR, CASPR2, LGI1, AMPAR and GABA_AR. Immunohistology indicated evidence of antibodies reactive with brain tissue, binding mainly to the hippocampus, the basal ganglia or the cerebellum in 26/218 (12%), with 8% of the preclinical or onset sera binding to the dentate gyrus/CA3 region or cerebellum. Only two individuals (one pre-clinical, one chronic) had antibodies binding the NMDAR and the binding was only weakly positive. No other specific antibodies were detected. Despite some immunoreactivity towards neuronal antigens on brain tissue, this was not mirrored by antibodies binding to live neurons, suggesting the presence of non-specific antibodies or those that bind non-pathogenic intracellular epitopes. NMDAR or the other neuronal surface antibodies tested were very infrequent in these patients. The evidence for pathogenic antibodies that could be causative of TS is weak.

Maternal thyroid autoimmunity associated with acute-onset neuropsychiatric disorders and global regression in offspring

Epidemiological studies, animal models, and case-control studies indicate maternal immune activation may be an important factor involved in disease expression of autism spectrum disorder (ASD), Tourette syndrome, and obsessive-compulsive disorder (OCD). We report eight children (mean age 6y 6mo [range 4-15y]; six males and two females) referred over a 2-year period with at least one of these neurodevelopmental disorders plus a maternal history of thyroid autoimmunity. Seven of eight children presented with an abrupt onset of neuropsychiatric symptoms (OCD [n=6], tics [n=5], and/or psychosis [n=1]), associated with an autistic or global regression. Four children had a pre-existing diagnosis of ASD. Six presentations were preceded by infection, and symptoms followed a relapsing-remitting course in seven children. All children responded to immunomodulatory treatment as indicated by a reduction in psychiatric symptoms, and seven children were also managed with conventional treatment with additional improvement. We propose that maternal autoimmunity can activate fetal microglia or alter transcription of neurodevelopmental vulnerability and/or immune genes in utero, and is an environmental factor that increases the expression and severity of neurodevelopmental problems, and susceptibility to deteriorations after infectious or stress stimuli. WHAT THIS PAPER ADDS: Maternal thyroid autoimmunity may represent a risk factor for neuropsychiatric disorders in offspring. Atypical neuropsychiatric features in these children may be due to maternal immune activation in utero.

Obsessive-Compulsive Disorder: Autoimmunity and Neuroinflammation

PURPOSE OF REVIEW

Here, we propose to review the immuno-inflammatory hypothesis in OCD given the concurrent incidence of autoimmune comorbidities, infectious stigma, and raised levels of inflammatory markers in a significant subset of patients. A better understanding of the immune dysfunction in OCD may allow stratifying the patients in order to design personalized pharmaco/psychotherapeutic strategies.

RECENT FINDINGS

A persistent low-grade inflammation involving both innate and adaptive immune system with coexisting autoimmune morbidities and stigma of infectious events has been prominently observed in OCD. Hence, specific treatments targeting inflammation/infection are a feasible alternative in OCD. This review highlights that OCD is associated with low-grade inflammation, neural antibodies, and neuro-inflammatory and auto-immune disorders. In some subset of OCD patients, autoimmunity is likely triggered by specific bacterial, viral, or parasitic agents with overlapping surface epitopes in CNS. Hence, subset-profiling in OCD is warranted to benefit from distinct immune-targeted treatment modalities.

Bidirectional relationship between eating disorders and autoimmune diseases

BACKGROUND

Immune system dysfunction may be associated with eating disorders (ED) and could have implications for detection, risk assessment, and treatment of both autoimmune diseases and EDs. However, questions regarding the nature of the relationship between these two disease entities remain. We evaluated the strength of associations for the bidirectional relationships between EDs and autoimmune diseases.

METHODS

In this nationwide population-based study, Swedish registers were linked to establish a cohort of more than 2.5 million individuals born in Sweden between January 1, 1979 and December 31, 2005 and followed up until December 2013. Cox proportional hazard regression models were used to investigate: (a) subsequent risk of EDs in individuals with autoimmune diseases; and (b) subsequent risk of autoimmune diseases in individuals with EDs.

RESULTS

We observed a strong, bidirectional relationship between the two illness classes indicating that diagnosis in one illness class increased the risk of the other. In women, the diagnoses of autoimmune disease increased subsequent hazards of anorexia nervosa (AN), bulimia nervosa (BN), and other eating disorders (OED). Similarly, AN, BN, and OED increased subsequent hazards of autoimmune diseases.Gastrointestinal-related autoimmune diseases such as, celiac disease and Crohn's disease showed a bidirectional relationship with AN and OED. Psoriasis showed a bidirectional relationship with OED. The previous occurence of type 1 diabetes increased the risk for AN, BN, and OED. In men, we did not observe a bidirectional pattern, but prior autoimmune arthritis increased the risk for OED.

CONCLUSIONS

The interactions between EDs and autoimmune diseases support the previously reported associations. The bidirectional risk pattern observed in women suggests either a shared mechanism or a third mediating variable contributing to the association of these illnesses.

Initial findings of striatum tripartite model in OCD brain samples based on transcriptome analysis

Obsessive-compulsive disorder (OCD) is a psychiatric disorder characterized by obsessions and/or compulsions. Different striatal subregions belonging to the cortico-striato-thalamic circuitry (CSTC) play an important role in the pathophysiology of OCD. The transcriptomes of 3 separate striatal areas (putamen (PT), caudate nucleus (CN) and accumbens nucleus (NAC)) from postmortem brain tissue were compared between 6 OCD and 8 control cases. In addition to network connectivity deregulation, different biological processes are specific to each striatum region according to the tripartite model of the striatum and contribute in various ways to OCD pathophysiology. Specifically, regulation of neurotransmitter levels and presynaptic processes involved in chemical synaptic transmission were shared between NAC and PT. The Gene Ontology terms cellular response to chemical stimulus, response to external stimulus, response to organic substance, regulation of synaptic plasticity, and modulation of synaptic transmission were shared between CN and PT. Most genes harboring common and/or rare variants previously associated with OCD that were differentially expressed or part of a least preserved coexpression module in our study also suggest striatum subregion specificity. At the transcriptional level, our study supports differences in the 3 circuit CSTC model associated with OCD.