Antigliadin Antibodies (AGA IgG) Are Related to Neurochemistry in Schizophrenia

Microstructural and Microvascular Alterations in Psychotic Spectrum Disorders: A Three-Compartment Intravoxel Incoherent Imaging and Free Water Model

BACKGROUND AND HYPOTHESIS

Microvascular and inflammatory mechanisms have been hypothesized to be involved in the pathophysiology of psychotic spectrum disorders (PSDs). However, data evaluating these hypotheses remain limited.

STUDY DESIGN

We applied a three-compartment intravoxel incoherent motion free water imaging (IVIM-FWI) technique that estimates the perfusion fraction (PF), free water fraction (FW), and anisotropic diffusion of tissue (FAt) to examine microvascular and microstructural changes in gray and white matter in 55 young adults with a PSD compared to 37 healthy controls (HCs).

STUDY RESULTS

We found significantly increased PF, FW, and FAt in gray matter regions, and significantly increased PF, FW, and decreased FAt in white matter regions in the PSD group versus HC. Furthermore, in patients, but not in the HC group, increased PF, FW, and FAt in gray matter and increased PF in white matter were significantly associated with poor performance on several cognitive tests assessing memory and processing speed. We additionally report significant associations between IVIM-FWI metrics and myo-inositol, choline, and N-acetylaspartic acid magnetic resonance spectroscopy imaging metabolites in the posterior cingulate cortex, which further supports the validity of PF, FW, and FAt as microvascular and microstructural biomarkers of PSD. Finally, we found significant relationships between IVIM-FWI metrics and the duration of psychosis in gray and white matter regions.

CONCLUSIONS

The three-compartment IVIM-FWI model provides metrics that are associated with cognitive deficits and may reflect disease progression.

Anticuerpos anti gliadina como factor asociado a la falta de respuesta a la vacunación anti hepatitis B en adultos

La hepatitis B es una enfermedad que afecta a 350 millones de personas en el mundo. Existen factores como la edad, el sexo, sobrepeso, enfermedades inmunológicas, diabetes mellitus, entre otros, que impiden la correcta respuesta inmunitaria a la vacunación anti hepatitis B. El objetivo de la investigación fue analizar la presencia de anticuerpos antigliadina y la falta de respuesta a la vacunación anti hepatitis B en adultos. La metodología de diseño descriptivo-no experimental, de tipo prospectivo, transversal y explicativo, incluyó 235 adultos seleccionados sin distinción de sexo o etnia con antecedentes de vacunación al virus de hepatitis B en cuyas muestras de suero se determinaron los anticuerpos anti antígeno de superficie del virus hepatitis B. El análisis estadístico se realizó con el programa Graph Pad Prism 8.0®. Los anticuerpos anti antígeno de superficie del virus hepatitis B estuvieron presentes en el 76% de la población estudiada. El 35,5% resultó con anticuerpos antigliadina elevados asociado a una hipo-respuesta frente a la vacuna virus hepatitis B. Factores como el índice de masa corporal y los antecedentes familiares de diabetes mellitus tipo 1 y 2 en los adultos estudiados, resultaron significativamente asociados a la falta de respuesta inmunitaria en individuos no respondedores

The potential of 1H-MRS in CNS drug development

RATIONALE

Proton magnetic resonance spectroscopy (¹H-MRS) is a cross-species neuroimaging technique that can measure concentrations of several brain metabolites, including glutamate and GABA. This non-invasive method has promise in developing centrally acting drugs, as it can be performed repeatedly within-subjects and be used to translate findings from the preclinical to clinical laboratory using the same imaging biomarker.

OBJECTIVES

This review focuses on the utility of single-voxel ¹H-MRS in developing novel glutamatergic or GABAergic drugs for the treatment of psychiatric disorders and includes research performed in rodent models, healthy volunteers and patient cohorts.

RESULTS

Overall, these studies indicate that ¹H-MRS is able to detect the predicted pharmacological effects of glutamatergic or GABAergic drugs on voxel glutamate or GABA concentrations, although there is a shortage of studies examining dose-related effects. Clinical studies have applied ¹H-MRS to better understand drug therapeutic mechanisms, including the glutamatergic effects of ketamine in depression and of acamprosate in alcohol dependence. There is an emerging interest in identifying patient subgroups with 'high' or 'low' brain regional ¹H-MRS glutamate levels for more targeted drug development, which may require ancillary biomarkers to improve the accuracy of subgroup discrimination.

CONCLUSIONS

Considerations for future research include the sensitivity of single-voxel ¹H-MRS in detecting drug effects, inter-site measurement reliability and the interpretation of drug-induced changes in ¹H-MRS metabolites relative to the known pharmacological molecular mechanisms. On-going technological development, in single-voxel ¹H-MRS and in related complementary techniques, will further support applications within CNS drug discovery.

The Differences between Gluten Sensitivity, Intestinal Biomarkers and Immune Biomarkers in Patients with First-Episode and Chronic Schizophrenia

Schizophrenia is a heterogeneous disorder without a fully elucidated etiology and mechanisms. One likely explanation for the development of schizophrenia is low-grade inflammation, possibly caused by processes in the gastrointestinal tract related to gluten sensitivity. The aims of this study were to: (1) compare levels of markers of gluten sensitivity, inflammation and gut permeability, and (2) determine associations between gluten sensitivity, inflammation, and intestinal permeability in patients with first-episode/chronic (FS/CS) schizophrenia and healthy individuals (HC). The total sample comprised 162 individuals (52 FS; 50 CS, and 60 HC). The examination included clinical variables, nutritional assessment, and serum concentrations of: high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), soluble CD14 (sCD14), anti-Saccharomyces cerevisiae antibody (ASCA), antigliadin antibodies (AGA) IgA/IgG, antibodies against tissue transglutaminase 2 (anti-tTG) IgA, anti-deamidated gliadin peptides (anti-DGP) IgG. A significant difference between groups was found in sCD14, ASCA, hs-CRP, IL-6 and AGA IgA levels. AGA IgG/IgA levels were higher in the FS (11.54%; 30.77%) and CS (26%; 20%) groups compared to HC. The association between intestinal permeability and inflammation in the schizophrenic patients only was noted. The risk for developing schizophrenia was odds ratio (OR) = 4.35 (95% confidence interval (CI 1.23-15.39) for AGA IgA and 3.08 (95% CI 1.19-7.99) for positive AGA IgG. Inflammation and food hypersensitivity reactions initiated by increased intestinal permeability may contribute to the pathophysiology of schizophrenia. The immune response to gluten in FS differs from that found in CS.

Microbiota-Orientated Treatments for Major Depression and Schizophrenia

Background and significance. There is a need to develop new hypothesis-driven treatment for both both major depression (MD) and schizophrenia in which the risk of depression is 5 times higher than the general population. Major depression has been also associated with poor illness outcomes including pain, metabolic disturbances, and less adherence. Conventional antidepressants are partly effective, and 44% of the subjects remain unremitted under treatment. Improving MD treatment efficacy is thus needed to improve the SZ prognosis. Microbiota-orientated treatments are currently one of the most promising tracks. Method. This work is a systematic review synthetizing data of arguments to develop microbiota-orientated treatments (including fecal microbiota transplantation (FMT)) in major depression and schizophrenia. Results. The effectiveness of probiotic administration in MD constitutes a strong evidence for developing microbiota-orientated treatments. Probiotics have yielded medium-to-large significant effects on depressive symptoms, but it is still unclear if the effect is maintained following probiotic discontinuation. Several factors may limit MD improvement when using probiotics, including the small number of bacterial strains administered in probiotic complementary agents, as well as the presence of a disturbed gut microbiota that probably limits the probiotics’ impact. FMT is a safe technique enabling to improve microbiota in several gut disorders. The benefit/risk ratio of FMT has been discussed and has been recently improved by capsule administration. Conclusion. Cleaning up the gut microbiota by transplanting a totally new human gut microbiota in one shot, which is referred to as FMT, is likely to strongly improve the efficacy of microbiota-orientated treatments in MD and schizophrenia and maintain the effect over time. This hypothesis should be tested in future clinical trials.

Measuring patient activation in Chinese patients with hypertension and/or diabetes: reliability and validity of the PAM13

Objective

Patient activation is important in the management of chronic diseases (CDs), especially hypertension and diabetes. The 13-item short form Patient Activation Measure (PAM13) is widely used, but data are lacking for China. The study aim was to assess the reliability and validity of the PAM13 in Chinese patients with hypertension and/or diabetes in a community management setting.

Methods

A cross-sectional survey was conducted at four community health centres in Kunming (Yunnan province, China) Participants were patients (n = 519) with hypertension and/or type 2 diabetes mellitus being managed at the community health centres. Patient activation was measured using the Chinese version of the PAM13. Reliability and validity were tested using Cronbach’s α and confirmatory factor analysis.

Results

The male to female ratio was 1:1.65. In total, 307 (60.3%) patients had ≤9 years of education and 213 (41.8%) had a low household income (≤5000 RMB/month). Cronbach’s α was 0.920 and item–total correlations ranged from 0.535 to 0.714. Confirmatory factor analysis showed a good fit to the data.

Conclusions

The PAM13 shows good reliability and validity for measuring patient activation in Chinese patients with CDs (hypertension and/or diabetes).

Randomized controlled trial of a gluten-free diet in patients with schizophrenia positive for antigliadin antibodies (AGA IgG): a pilot feasibility study

BACKGROUND

Approximately one-third of people with schizophrenia have elevated levels of anti-gliadin antibodies of the immunoglobulin G type (AGA IgG) — a higher rate than seen in healthy controls. We performed the first double-blind clinical trial of gluten-free versus gluten-containing diets in a subset of patients with schizophrenia who were positive for AGA IgG.

METHODS

In this pilot feasibility study, 16 participants with schizophrenia or schizoaffective disorder who had elevated AGA IgG (≥ 20 U) but were negative for celiac disease were admitted to an inpatient unit for a 5-week trial. All participants received standardized gluten-free meals and were randomized in a double-blind fashion to receive a shake containing 10 g of gluten flour or 10 g of rice flour each day. Participants were rated for psychiatric, cognitive and gastrointestinal symptoms at baseline and endpoint.

RESULTS

Of the 16 participants, 14 completed the 5-week trial (2 discontinued early for administrative reasons). Compared with participants on the gluten-containing diet, participants on the gluten-free diet showed improvement on the Clinical Global Impressions scale (Cohen d = –0.75) and in negative symptoms (Cohen d = –0.53). We noted no improvement in positive or global cognitive symptoms, but did observe an improvement in attention favouring the gluten-free diet (Cohen d = 0.60). Robust improvements in gastrointestinal adverse effects occurred in the gluten-free group relative to the glutencontaining group. Adverse effects were similar between groups.

LIMITATIONS

This study was limited by its small sample size; larger studies are needed.

CONCLUSION

This feasibility study suggests that removal of gluten from the diet is associated with improvement in psychiatric and gastrointestinal symptoms in people with schizophrenia or schizoaffective disorder.

Gut permeability and mimicry of the Glutamate Ionotropic Receptor NMDA type Subunit Associated with protein 1 (GRINA) as potential mechanisms related to a subgroup of people with schizophrenia with elevated antigliadin antibodies (AGA IgG)

About one third of people with schizophrenia have elevated IgG antibodies to gliadin (AGA IgG) and increased inflammation. Understanding the mechanism by which this immune response occurs is critical to the development of personalized treatments. We examined gut permeability and mimicry to the glutamate receptor as possible mechanisms related to high gliadin antibodies (AGA IgG) seen in some people with schizophrenia. The Glutamate Ionotropic Receptor NMDA type Subunit Associated with protein 1 (GRINA) has a similar protein structure to gliadin representing a potential target for cross reactivity or mimicry. In a population of schizophrenia subjects (N = 160) and healthy controls (N = 80) we analyzed serum samples for both GRINA and Anti-Saccharomyces Cerevisiae antibodies (ASCA), related to gut permeability. Schizophrenia patients compared to controls had a higher prevalence of positivity to ASCA IgA (p = 0.004) and IgG (p < 0.001). Multinomial logistic regression showed an association between AGA IgG and ASCA IgG in schizophrenia (p = 0.05 for the estimated regression coefficient) but not in healthy controls (p = 0.13). GRINA IgG was higher in schizophrenia patients than in healthy controls (0.43 ± 0.30 vs. 0.22 ± 0.24, p < 0.001). Logistic regressions showed an association between AGA IgG and GRINA IgG in schizophrenia (p = 0.016 for the estimated regression coefficient) but not for the controls (p = 0.471). Thus, we propose that mimicry through the presence of cross-reactivity between gliadin and GRINA might disrupt the functions of the glutamate system and relate to illness pathophysiology in those with schizophrenia and elevated AGA IgG.

Breakdown of the Paracellular Tight and Adherens Junctions in the Gut and Blood Brain Barrier and Damage to the Vascular Barrier in Patients with Deficit Schizophrenia

Deficit schizophrenia is characterized by leaky intestinal tight and adherens junctions and bacterial translocation. Here we examine whether (deficit) schizophrenia is accompanied by leaky paracellular, transcellular, and vascular barriers in the gut and blood-brain barriers. We measured IgA responses to occludin, claudin-5, E-cadherin, and β-catenin (paracellular pathway, PARA); talin, actin, vinculin, and epithelial intermediate filament (transcellular pathway, TRANS); and plasmalemma vesicle-associated protein (PLVAP, vascular pathway) in 78 schizophrenia patients and 40 controls. IgA responses to claudin-5, E-cadherin, and β-catenin, the sum of the four PARA proteins, and the ratio PARA/TRANS were significantly higher in deficit schizophrenia patients than in nondeficit schizophrenia patients and controls. A large part of the variance in PHEMN (psychosis, hostility, excitation, mannerism, and negative) symptoms, psychomotor retardation, formal thought disorders, verbal fluency, word list memory, word list recall, and executive functions was explained by the PARA/TRANS ratio coupled with plasma IgA responses to Gram-negative bacteria, IgM to malondialdehyde, CCL-11 (eotaxin), IgA levels of the ratio of noxious to more protective tryptophan catabolites (NOX/PRO TRYCATs), and a plasma immune activation index. Moreover, IgA levels to Gram-negative bacteria were significantly associated with IgA to E-cadherin, β-catenin, and PLVAP, while IgA levels to claudin-5 were significantly predicted by IgA to E-cadherin, NOX/PRO TRYCAT ratio, Gram-negative bacteria, and CCL11. The phenomenology of the deficit syndrome is to a large extent explained by the cumulative effects of lowered natural IgM, breakdown of the paracellular and vascular pathways, increased bacterial translocation, peripheral immune-inflammatory responses, and indices of BBB breakdown.

MRI investigation of immune dysregulation in schizophrenia

PURPOSE OF REVIEW

Immune dysregulation has been suggested as a pathophysiological pathway in schizophrenia. MRI could aid in investigating this pathological process in more detail. This review aims to provide an overview of recent MRI findings of immune dysregulation in schizophrenia. In addition, we discuss the potential of more recently developed MRI techniques.

RECENT FINDINGS

Subtle and indirect signs of immune dysregulation are detected in schizophrenia, particularly in the early stages of the disease. In recently diagnosed schizophrenia patients, findings based on conventional and novel MRI techniques suggest increased glutamate levels and increases in extracellular free water that may be associated with glial activation. As the disease progresses, reductions in white matter, myelin and grey matter seem present, that may point to neurodegeneration.

SUMMARY

These MRI findings support the notion of immune dysregulation in early psychosis, which may result in neurodegeneration in later stages. However, these findings are not unequivocal. Therefore, we recommend multimodal MRI studies to further elucidate the role of different immune-related processes in schizophrenia. Future studies should consider inter-individual variability in immune dysregulation, for example, by focusing on recent-onset psychosis and/or by using stratification based on central or peripheral immune markers.

Upregulation of the Intestinal Paracellular Pathway with Breakdown of Tight and Adherens Junctions in Deficit Schizophrenia

In 2001, the first author of this paper reported that schizophrenia is associated with an increased frequency of the haptoglobin (Hp)-2 gene. The precursor of Hp-2 is zonulin, a molecule that affects intercellular tight junction integrity. Recently, we reported increased plasma IgA/IgM responses to Gram-negative bacteria in deficit schizophrenia indicating leaky gut and gut dysbiosis. The current study was performed to examine the integrity of the paracellular (tight and adherens junctions) and transcellular (cytoskeletal proteins) pathways in deficit versus non-deficit schizophrenia. We measured IgM responses to zonulin, occludin, E-cadherin, talin, actin, and vinculin in association with IgA responses to Gram-negative bacteria, CCL-11, IgA responses to tryptophan catabolites (TRYCATs), immune activation and IgM to malondialdehyde (MDA), and NO-cysteinyl in 78 schizophrenia patients and 40 controls. We found that the ratio of IgM to zonulin + occludin/talin + actin + viculin (PARA/TRANS) was significantly greater in deficit than those in non-deficit schizophrenia and higher in schizophrenia than those in controls and was significantly associated with increased IgA responses to Gram-negative bacteria. IgM responses to zonulin were positively associated with schizophrenia (versus controls), while IgM to occludin was significantly associated with deficit schizophrenia (versus non-deficit schizophrenia and controls). A large part of the variance (90.8%) in negative and PHEM (psychosis, hostility, excitation, and mannerism) symptoms was explained by PARA/TRANS ratio, IgA to Gram-negative bacteria, IgM to E-cadherin and MDA, and memory dysfunctions, while 53.3% of the variance in the latter was explained by PARA/TRANS ratio, IgA to Gram-negative bacteria, CCL-11, TRYCATs, and immune activation. The results show an upregulated paracellular pathway with breakdown of the tight and adherens junctions and increased bacterial translocation in deficit schizophrenia. These dysfunctions in the intestinal paracellular route together with lowered natural IgM, immune activation, and production of CCL-11 and TRYCATs contribute to the phenomenology of deficit schizophrenia.

Proton magnetic resonance spectroscopy changes in a longitudinal schizophrenia study: a pilot study in eleven patients

PURPOSE

Investigation of the longitudinal effect of schizophrenia on changes in various brain-metabolite levels and their relationships with cognitive deficits that have not been fully explained yet.

METHODS

Five years subsequent to their first examination for their first episode of schizophrenia, eleven patients from an original group of 30 were reexamined. Their cognitive functions were assessed with the Wisconsin Card Sorting Test. Magnetic resonance imaging and proton magnetic resonance spectroscopy were performed on a 1.5 T scanner. Voxels of 8 cm³ were positioned in the left frontal lobe, left temporal lobe, and the left thalamus. The study had a naturalistic design, and patients were treated with various antipsychotics.

RESULTS

No significant statistical differences between the baseline and follow-up in N-acetylaspartate (NAA:creatine plus phosphocreatine [Cr] and NAA/H₂O) levels were observed in any region of interest. We found a significant statistical correlation between 5-year difference in frontal NAA/Cr levels and duration of the last antipsychotic treatment in this period (R=0.908, P=0.012). We found a trend (P=0.068) toward lower choline-containing compounds (Cho/Cr ratio) in the temporal lobe over 5 years and a trend (P=0.079) in higher glutamate-glutamine- GABA (Glx/H₂O) levels in the left thalamus. The patients showed social and clinical improvement at follow-up examination, and there were no changes in Wisconsin Card Sorting Test results.

CONCLUSION

The observed tendency toward decline in choline ratio might have been due to decreased temporal cell density or impaired neuron-membrane or myelin functions. A tendency for higher Glx levels suggest the involvement of thalamus dysfunction in the chronic schizophrenia process. The lack of NAA decrease might have been due to effective antipsychotic treatment. Further longitudinal studies on large patient groups are required to confirm these metabolic changes in schizophrenia.

Autoimmune phenotypes in schizophrenia reveal novel treatment targets

Typical and atypical antipsychotics are the first-line treatments for schizophrenia, but these classes of drugs are not universally effective, and they can have serious side effects that impact compliance. Antipsychotic drugs generally target the dopamine pathways with some variation. As research of schizophrenia pathophysiology has shifted away from a strictly dopamine-centric focus, the development of new pharmacotherapies has waned. A field of inquiry with centuries-old roots is gaining traction in psychiatric research circles and may represent a new frontier for drug discovery in schizophrenia. At the forefront of this investigative effort is the immune system and its many components, pathways and phenotypes, which are now known to actively engage the brain. Studies in schizophrenia reveal an intricate association of environmentally-driven immune activation in concert with a disrupted genetic template. A consistent conduit through this gene-environmental milieu is the gut-brain axis, which when dysregulated can generate pathological autoimmunity. In this review, we present epidemiological and biochemical evidence in support of an autoimmune component in schizophrenia and depict gut processes and a dysbiotic microbiome as a source and perpetuator of autoimmune dysfunction in the brain. Within this framework, we review the role of infectious agents, inflammation, gut dysbioses and autoantibody propagation on CNS pathologies such as neurotransmitter receptor hypofunction and complement pathway-mediated synaptic pruning. We then review the new pharmacotherapeutic horizon and novel agents directed to impact these pathological conditions. At the core of this discourse is the understanding that schizophrenia is etiologically and pathophysiologically heterogeneous and thus its treatment requires individualized attention with disease state variants diagnosed with objective biomarkers.

Anti gliadin antibodies (AGA IgG) related to peripheral inflammation in schizophrenia

Altered immune function and inflammation are seen in schizophrenia, however, peripheral inflammatory markers are not consistently elevated in all people, suggesting inflammation may be present only in a subgroup. We measured TNF-α and IL-Iβ in 100 people with schizophrenia or schizoaffective disorder and correlated these with antibodies to gliadin, a protein found in wheat, barley and rye that has been found to be elevated in some people with schizophrenia. We hypothesized that higher peripheral antigliadin antibodies (AGA IgG) would be associated with higher peripheral inflammation as measured by TNF-α and IL-1β. Mean log transformed values of TNF-α, (p=.029) and IL-1β (p=.016) were over twofold higher in people with schizophrenia who had high levels of AGA IgG (≥7 U) compared to those who did not have positivity to AGA IgG. We found a significant positive correlation between AGA IgG and the log transformed TNF-α (r=0.42, p<.0001) as well as IL-Iβ (r=0.51, p<.0001). The relationship was independent of cigarette smoking, body mass index and antipsychotic medications. People with schizophrenia having higher levels of AGA IgG show higher levels of peripheral inflammation and may define a subgroup with distinct pathophysiology and potentially novel treatment targets.