Increase in HLA-DR immunoreactive microglia in frontal and temporal cortex of chronic schizophrenics

Inflammatory processes in schizophrenia: a promising neuroimmunological target for the treatment of negative/cognitive symptoms and beyond

Emerging evidence indicates that schizophrenia is associated with activated peripheral and central inflammatory responses. Such inflammatory processes seem to be influenced by a number of environmental and genetic predisposition factors, and they may critically depend on and contribute to the progressive nature of schizophrenic disease. There is also appreciable evidence to suggest that activated inflammatory responses can undermine disease-relevant affective, emotional, social, and cognitive functions, so that inflammatory processes may be particularly relevant for the precipitation of negative and cognitive symptoms of schizophrenia. Recent clinical trials of anti-inflammatory pharmacotherapy in this disorder provide promising results by showing superior beneficial treatment effects when standard antipsychotic drugs are co-administered with anti-inflammatory compounds, as compared with treatment outcomes using antipsychotic drugs alone. Given the limited efficacy of currently available antipsychotic drugs to ameliorate negative and cognitive symptoms, the further exploration of inflammatory mechanisms and anti-inflammatory strategies may open fruitful new avenues for improved treatment of symptoms undermining affective, emotional, social and cognitive functions pertinent to schizophrenic disease.

When cortical development goes wrong: schizophrenia as a neurodevelopmental disease of microcircuits

Schizophrenia probably has a developmental origin. This review refers to three of our published series of studies related to this hypothesis: loss of dendritic spines on cerebral neocortical pyramidal neurons, decreased numerical density of glutamatergic neurons, and microgliosis. First, brains of schizophrenic patients and non-schizophrenic controls were obtained post mortem and blocks of multiple cortical areas impregnated with a Rapid Golgi method. Spines were counted on the dendrites of pyramidal neurons of which the soma was in layer III (which takes part in corticocortical connectivity) and which met strict criteria for impregnation quality. Data were obtained blind: diagnoses were only revealed by a third party after measurements were completed. The mean spine count in all cortical areas studied in the control series was 243 mm(-1) of dendrite and in the schizophrenics 108. Measurements in frontal and temporal association cortex showed the greatest reduction in spine number in schizophrenia (299 in control frontal cortex and 101 in schizophrenics, and 276 mm(-1) in control temporal cortex and 125 in schizophrenics). There was no correlation of spine loss with age at death. Our results support the concept of a neurodevelopmental defect in the neuropil affecting glutamatergic neurons in schizophrenia and may help to explain loss of cortical volume without loss of neurons. In a second part of our study we used an antibody to the kainate receptor subunit GluR 5/6/7 and showed a decrease in numerical density of presumed glutamatergic neurons in schizophrenic orbitofrontal cortex. Finally, as glia play a major role in the developing nervous system, we investigated whether schizophrenia was associated with glial changes in frontal and temporal cortex. Astroglia and microglia were identified in schizophrenic and control brains, using antibodies to glial fibrillary acidic protein (GFAP) and class II human leucocyte antigen (HLA-DR), respectively. Significant increases were found in microglial numerical density in schizophrenics compared with controls: 28% in frontal area 9 (115 cells mm(-2) compared with 89), and a 57% increase in temporal area 22 (139 cells mm(-2) compared with 88). For both areas, astroglia showed no significant differences between schizophrenics and controls. No significant differences were found in cortical thickness or total neuronal numerical density between the two groups. This specific increase in numerical density of microglia in temporal and frontal cortex of chronic schizophrenics, not related to aging, could be related to possible changes in cortical neuropil architecture as revealed by loss of dendritic spines.

Searching for neuropathology: gliosis in schizophrenia

The neuropathology of schizophrenia remains elusive. One indication of this elusiveness is that the literature, in contrast to that on the neuropathology of almost any other disease, deals predominantly with measures of normal structures rather than with the demonstration and characterization of pathological structures. An important exception to this trend has been the continued search, over four decades, for reactive glia. In this article, we review histological and radiological evidence for and against astrocytosis and microgliosis specifically associated with schizophrenia. The studies are generally limited by small samples, flawed designs, and potentially biased methods of counting cells. Interpretation of these studies is further complicated by the frequent presence of glial reactions in older individuals without psychiatric disease. Nonetheless, some of the positive findings in the literature cannot easily be dismissed. A sufficiently large autopsy study, weighted toward younger subjects, could provide a definitive answer, which if positive could be a major step toward finding an underlying pathological process.

Immune and neuroimmune alterations in mood disorders and schizophrenia

A large number of publications over the past 20 years have indicated that immune system function is altered in schizophrenia and mood disorder patients. This chapter reviews the evidence, which suggests that a proinflammatory state of the cytokine network induces psychopathologic symptoms and may be involved in the pathogenesis and pathophysiology of these major mental illnesses. The authors also present recent data, which relates immune activation to present theories on the influence of activated immune cells in altering brain function. They also focus on the role of the environment in immune activation and on the role of the microbiome and gut flora. Increased understanding of such factors could help in the development of novel treatment strategies and improved clinical management of mental disorders.

Serum S100B: a potential biomarker for suicidality in adolescents?

Background

Studies have shown that patients suffering from depression or schizophrenia often have immunological alterations that can be detected in the blood. Others reported a possible link between inflammation, a microgliosis and the blood-brain barrier (BBB) in suicidal patients. Serum S100B is a marker of BBB function commonly used to study cerebrovascular wall function.

Methods

We measured levels of S100B in serum of 40 adolescents with acute psychosis, 24 adolescents with mood disorders and 20 healthy controls. Patients were diagnosed according to DSM-IV TR criteria. We evaluated suicidal ideation using the suicidality subscale of the Brief Psychiatric Rating Scale for Children (BPRS-C).

Results

Serum S100B levels were significantly higher (p<0.05) and correlated to severity of suicidal ideation in patients with psychosis or mood disorders, independent of psychiatric diagnosis. Patients with a BPRS-C suicidality subscores of 1–4 (low suicidality) had mean serum S100B values +/− SEM of 0.152+/−0.020 ng/mL (n = 34) compared to those with BPRS-C suicidality subscores of 5–7 (high suicidality) with a mean of 0.354+/−0.044 ng/mL (n = 30). This difference was statistically significant (p<0.05).

Conclusion

Our data support the use of S100B as an adjunctive biomarker to assess suicidal risk in patients with mood disorders or schizophrenia.

The mononuclear phagocyte system and its cytokine inflammatory networks in schizophrenia and bipolar disorder

This review describes patients with schizophrenia and bipolar disorder. In such patients, a high inflammatory set point of circulating monocytes at the transcriptome level is observed, involving various inflammatory transcripts forming distinct fingerprints (the transcriptomic monocyte fingerprint in schizophrenia overlaps with that in bipolar disorder, but also differs with it at points). There are increased levels of compounds of the IL-1, IL-6 and TNF system in the serum (be it modest and inconsistent). There is also evidence that the IL-2 system is activated in patients with schizophrenia (and perhaps those with mania), although independently of the activation of the IL-1, IL-6 and TNF systems, suggesting separate inducing mechanisms for monocyte and T-cell activation. It is not yet known whether such T cell activation involves the Th1/Th2/Th17 or Treg systems.

Clinical perspectives on autoimmune processes in schizophrenia

This article reviews the epidemiology of autoimmune conditions in schizophrenia, symptom manifestations of autoimmune conditions resembling schizophrenia, and the immunological changes observed in schizophrenia; and reflects on their associations with neurodevelopment, neurodegeneration, clinical course, and management of schizophrenia.

Two-dimensional assessment of cytoarchitecture in the superior temporal white matter in schizophrenia, major depressive disorder and bipolar disorder

Evidence from brain imaging studies indicates that white matter volume, density and fractional anisotropy may be altered in individuals with schizophrenia and bipolar disorder. However, the molecular correlates of these deficits remain unknown. In this study we performed a cytoarchitectural assessment of the white matter adjacent to the planum temporale (PT), an auditory association region located within the superior temporal gyrus, in subjects with schizophrenia, bipolar disorder, major depressive disorder and controls (15 subjects per group). Using two-dimensional measures, we recorded the cell density, distribution and size of all neurons and glial nuclei within this region. Glial density was lower in the schizophrenia group, relative to the control group. Neuronal density, neuronal size, and glial nuclear size did not differ between groups. No significant differences in neuronal clustering were observed in the patient groups. Further studies are required to examine whether the observed decrease in glial density within the superior temporal white matter in schizophrenia reflects a deficit in any individual glial cell population.

Neuroinflammation in schizophrenia-related psychosis: a PET study

Schizophrenia is a chronic and disabling brain disease characterized by psychotic episodes with unknown etiology. It is suggested that neuroinflammation plays a role in the pathophysiology of schizophrenia. Neuroinflammation is characterized by the activation of microglia cells, which show an increase in the expression of the peripheral benzodiazepine receptor. The isoquinoline (R)-N-(11)C-methyl-N-(1-methylpropyl)-1-(2-chlorophenyl)isoquinoline-3-carboxamide ((11)C-(R)-PK11195) is a peripheral benzodiazepine receptor ligand that can be used for the imaging of activated microglia cells, and thus neuroinflammation, with PET. We hypothesized that neuroinflammation would be more profound in schizophrenic patients during psychosis, and it was therefore investigated whether neuroinflammation was present in patients within the schizophrenia spectrum who were in a psychotic phase.

METHODS

Seven patients within the schizophrenia spectrum who were recovering from psychosis were included. Recovering psychosis was defined by a score of 5 or more on 1 item of the positive scale of the positive and negative symptoms scale (PANSS) or a score of 4 on 2 items. The patients were compared with 8 age-matched healthy volunteers. Dynamic 60-min PET scans were acquired after the injection of (11)C-(R)-PK11195. All subjects underwent T1- and T2-weighted MRI, and the scans were visually examined for abnormalities and used for anatomic coregistration in data analysis. The PET data were analyzed with a 2-tissue-compartment model to calculate the binding potential, using the metabolite-corrected plasma curve as input.

RESULTS

A significantly higher binding potential of (11)C-(R)-PK11195, indicative of neuroinflammation, was found in the hippocampus of schizophrenic patients than in healthy volunteers (2.07 +/- 0.42 vs. 1.37 +/- 0.30; P = 0.004). A nonsignificant 30% higher (11)C-(R)-PK11195 binding potential was found in the whole-brain gray matter of schizophrenic patients. The MR images did not reveal any visual abnormalities.

CONCLUSION

The present study suggests that focal neuroinflammation may play an important role in schizophrenia during psychosis.

Glial cells in schizophrenia: pathophysiological significance and possible consequences for therapy

In the last 10 years, structural, molecular and functional changes in glial cells have become a major focus of interest in the search for the neurobiological foundations of schizophrenia. While neuronal degeneration, as seen in typical degenerative brain diseases, cannot be found in post-mortem brains of psychotic disorders called 'schizophrenia', many studies show abnormalities in the connecting elements between the nerve cell bodies (synapses, dendrites and axons) and in all three types of glial cells. There is accumulating evidence of reduced numbers of oligodendrocytes and altered gene expression of myelin/oligodendrocyte-related genes that might explain white matter abnormalities and disturbed inter- and intra-hemispheric connectivity, which have frequently been described in schizophrenia. Earlier reports of increased astrocyte densities as a sign of gliosis could not be confirmed by later studies; however, the expression of several astrocyte-related genes is abnormal. Since astrocytes play a key role in the synaptic metabolism of glutamate and monamines, astrocyte dysfunction may well be related to the current transmitter theories of schizophrenia. Results in increased densities of microglial cells, which act as the main cells for immune defence in the brain, are more controversial. There are, however, higher microglial cell numbers in psychotic patients dying from suicide, and several studies reported altered expression of microglia-related surface markers in schizophrenia, suggesting that immunological/inflammatory factors may be relevant for the pathophysiology of psychosis. Searches for future therapeutic options should aim at compensating disturbed functions of oligodendrocytes, astrocytes and microglial cells, by which at least some aspects of the pathophysiology of the very inhomogeneous clinical syndrome of schizophrenia might be explained.

Altered volume and hemispheric asymmetry of the superficial cortical layers in the schizophrenia planum temporale

In vivo structural MRI studies in schizophrenia auditory cerebral cortex have reported smaller volumes and, less consistently, have reported altered hemispheric asymmetry of volumes. We used autopsy brains from 19 schizophrenia and 18 nonpsychiatric male subjects to measure the volume asymmetry of the planum temporal (PT). We then used the most recently autopsied 11 schizophrenia and 10 nonpsychiatric brains to measure the widths and fractional volumes of the upper (I-III) and lower (IV-VI) layers. Measurements of whole PT gray matter volumes did not show significant changes in schizophrenia. Nevertheless, laminar volume measurements revealed that the upper layers of the PT comprise a smaller fraction of the total cortex in schizophrenia than in nonpsychiatric brains. Subdivision of the PT showed that this change was especially prominent caudally, beyond Heschl's gyrus, whereas similar but less pronounced changes were found in the rostral PT and Heschl's gyrus. Complementary measures of laminar widths showed that the altered fractional volume in the caudal left PT was due mainly to approximately 8% thinner upper layers. However, the caudal right PT had a different profile, with thicker lower layers and comparatively unchanged upper layers. Thus, in the present study, laminar measurements provided a more sensitive method for detecting changes than measurement of whole PT volumes. Besides findings in schizophrenia, our cortical width measurements revealed normal hemispheric asymmetries consistent with previous reports. In schizophrenia, the thinner upper layers of the caudal PT suggest disrupted corticocortical processing, possibly affecting the multisensory integration and phonetic processing of this region.

Schizophrenia: from the brain to peripheral markers. A consensus paper of the WFSBP task force on biological markers

Objective. The phenotypic complexity, together with the multifarious nature of the so-called "schizophrenic psychoses", limits our ability to form a simple and logical biologically based hypothesis for the disease group. Biological markers are defined as biochemical, physiological or anatomical traits that are specific to particular conditions. An important aim of biomarker discovery is the detection of disease correlates that can be used as diagnostic tools. Method. A selective review of the WFSBP Task Force on Biological Markers in schizophrenia is provided from the central nervous system to phenotypes, functional brain systems, chromosomal loci with potential genetic markers to the peripheral systems. Results. A number of biological measures have been proposed to be correlated with schizophrenia. At present, not a single biological trait in schizophrenia is available which achieves sufficient specificity, selectivity and is based on causal pathology and predictive validity to be recommended as diagnostic marker. Conclusions. With the emergence of new technologies and rigorous phenotypic subclassification the identification of genetic bases and assessment of dynamic disease related alterations will hopefully come to a new stage in the complex field of psychiatric research.

Cytokines and schizophrenia: Microglia hypothesis of schizophrenia

The etiology of schizophrenia remains unclear, while there has been a growing amount of evidence for the neuroinflammation and immunogenetics, which are characterized by an increased serum concentration of several pro-inflammatory cytokines. Despite the fact that microglia comprise only <10% of the total brain cells, microglia respond rapidly to even minor pathological changes in the brain and may contribute directly to the neuronal degeneration by producing various pro-inflammatory cytokines and free radicals. In many aspects, the neuropathology of schizophrenia has recently been reported to be closely associatedwith microglial activation. Previous studies have shown the inhibitory effects of some typical/atypical antipsychotics on the release of inflammatory cytokines and free radicals from activated microglia, both of which have recently been known to cause a decrease in neurogenesis as well as white matter abnormalities in the brains of patients with schizophrenia. The microglia hypothesis of schizophrenia may shed new light on the therapeutic strategy for schizophrenia.

The antipsychotic spiperone attenuates inflammatory response in cultured microglia via the reduction of proinflammatory cytokine expression and nitric oxide production

Glial activation and neuroinflammatory processes play an important role in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and HIV dementia. Activated glia cells can secrete various proinflammatory cytokines and neurotoxic mediators, which may influence neuronal cell survival. Recent studies have demonstrated that glia cell-mediated neuroinflammation is also related to the pathophysiology of schizophrenia. In the present study, anti-inflammatory and neuroprotective effects of antipsychotics were investigated using cultured brain cells as a model. The results showed that spiperone significantly decreased the production of nitric oxide in lipopolysaccharide-stimulated BV-2 microglia cells, primary microglia and primary astrocyte cultures. Spiperone also significantly inhibited nitric oxide production in adenosine 5'-triphosphate (ATP)-stimulated primary microglia cultures. Spiperone markedly decreased the production of tumor necrosis factor-alpha in BV-2 microglia cells. Spiperone attenuated the expression of inducible nitric oxide synthase and proinflammatory cytokines such as interleukin-1beta and tumor necrosis factor-alpha at mRNA levels in BV-2 microglia cells. Spiperone inhibited nuclear translocation and DNA binding of the p65 subunit of nuclear factor kappa B (NF-kappaB), inhibitor of kappa B (IkappaB) degradation, and phosphorylation of p38 mitogen-activated protein kinase in the lipopolysaccharide-stimulated BV-2 microglia cells. Moreover, spiperone was neuroprotective, as the drug reduced microglia-mediated neuroblastoma cell death in the microglia/neuron co-culture. These results imply that the antipsychotic spiperone has anti-inflammatory and neuroprotective effects in the central nervous system by modulating glial activation.

Microglia activation in recent-onset schizophrenia: a quantitative (R)-[11C]PK11195 positron emission tomography study

BACKGROUND

Schizophrenia is a brain disease involving progressive loss of gray matter of unknown cause. Most likely, this loss reflects neuronal damage, which should, in turn, be accompanied by microglia activation. Microglia activation can be quantified in vivo using (R)-[(11)C]PK11195 and positron emission tomography (PET). The purpose of this study was to investigate whether microglia activation occurs in patients with recent-onset schizophrenia.

METHODS

Ten patients with recent-onset schizophrenia and 10 age-matched healthy control subjects were included. A fully quantitative (R)-[(11)C]PK11195 PET scan was performed on all subjects, including arterial sampling to generate a metabolite-corrected input curve.

RESULTS

Compared with control subjects, binding potential of (R)-[(11)C]PK11195 in total gray matter was increased in patients with schizophrenia. There were no differences in other PET parameters.

CONCLUSIONS

Activated microglia are present in schizophrenia patients within the first 5 years of disease onset. This suggests that, in this period, neuronal injury is present and that neuronal damage may be involved in the loss of gray matter associated with this disease. Microglia may form a novel target for neuroprotective therapies in schizophrenia.

Chronic psychotropic drug treatment causes differential expression of connexin 43 and GFAP in frontal cortex of rats

Astrocytic markers glial fibrillary acidic protein (GFAP) and connexin 43 (CX43) are known to have altered expression in brains of subjects with psychiatric disorders including autism and major depression. The current study investigated whether GFAP and CX43 expressions are affected by several commonly used psychotropic medications (clozapine, fluoxetine, haloperidol, lithium, olanzapine, and valproic acid). Using SDS-PAGE and western blotting technique, we observed that CX43 protein expression in prefrontal cortex was significantly increased following chronic treatment with fluoxetine and clozapine, while it was significantly decreased by haloperidol and lithium. GFAP protein expression was significantly decreased following chronic treatment with clozapine and valproic acid. These results suggest that astroglial markers GFAP and CX43 could be potential targets for therapeutic intervention.

Mourning and melancholia revisited: correspondences between principles of Freudian metapsychology and empirical findings in neuropsychiatry

Freud began his career as a neurologist studying the anatomy and physiology of the nervous system, but it was his later work in psychology that would secure his place in history. This paper draws attention to consistencies between physiological processes identified by modern clinical research and psychological processes described by Freud, with a special emphasis on his famous paper on depression entitled 'Mourning and melancholia'. Inspired by neuroimaging findings in depression and deep brain stimulation for treatment resistant depression, some preliminary physiological correlates are proposed for a number of key psychoanalytic processes. Specifically, activation of the subgenual cingulate is discussed in relation to repression and the default mode network is discussed in relation to the ego. If these correlates are found to be reliable, this may have implications for the manner in which psychoanalysis is viewed by the wider psychological and psychiatric communities.

The effect of atypical antipsychotics, perospirone, ziprasidone and quetiapine on microglial activation induced by interferon-gamma

An accumulating body of evidences point to the significance of neuroinflammation and immunogenetics in schizophrenia, characterized by increased serum concentration of several pro-inflammatory cytokines. In the central nervous system (CNS), the microglial cells are the major immunocompetent cells which release pro-inflammatory cytokines, nitric oxide (NO) and reactive oxygen species to mediate the inflammatory process. In the present study, we investigated whether or not atypical antipsychotics, namely perospirone, quetiapine and ziprasidone, would have anti-inflammatory effects on the activated microglia which may potentiate neuroprotection. All three atypical antipsychotics significantly inhibited NO generation from activated microglia while perospirone and quetiapine significantly inhibited the TNF-alpha release from activated microglia. Antipsychotics, especially perospirone and quetiapine may have an anti-inflammatory effect via the inhibition of microglial activation, which is not only directly toxic to neurons but also has an inhibitory effect on neurogenesis and oligodendrogenesis, both of which have been reported to play a crucial role in the pathology of schizophrenia.

Immunological aspects in the neurobiology of suicide: elevated microglial density in schizophrenia and depression is associated with suicide

OBJECTIVES

Suicide has a high prevalence in patients with schizophrenia and affective disorder. Our recent postmortem study [Steiner J, Mawrin C, Ziegeler A, Bielau H, Ullrich O, Bernstein HG, Bogerts B. Distribution of HLA-DR-positive microglia in schizophrenia reflects impaired cerebral lateralization. Acta Neuropathologica (Berl) 2006;112:305-16.] revealed increased microglial densities in two schizophrenic patients who had committed suicide. Therefore, the hypothesis of microglial activation during acute psychosis was proposed. Alternatively, "suicide" could be a diagnosis-independent factor leading to microgliosis.

METHODS

To clarify this question, microglial HLA-DR expression was analyzed by immunohistochemistry in the dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), mediodorsal thalamus (MD) and hippocampus of 16 schizophrenics, 14 depressed patients with affective disorder and 10 matched controls. A subgroup of six schizophrenics and seven patients with affective disorder who committed suicide was included.

RESULTS

ANOVA revealed no effect of diagnosis on microglial density (DLPFC: P=0.469; ACC: P=0.349; MD: P=0.569; hippocampus: P=0.497). However, significant microgliosis was observed in the DLPFC (P=0.004), ACC (P=0.012) and MD (P=0.004) of suicide patients. A similar trend was seen in the hippocampus (P=0.057).

CONCLUSION

In conclusion, immunological factors may play a hitherto underestimated role in suicide. First, microglial activation might be interpreted as a consequence of presuicidal stress. Second, one might speculate a causal link between microglial activation and suicidal behaviour, such as neuroendocrine factors, cytokines, and nitric oxide, which are released from microglial cells and are known to modulate noradrenergic or serotonergic neurotransmission and thus may trigger suicidality.

Deficit of perineuronal oligodendrocytes in the prefrontal cortex in schizophrenia and mood disorders

OBJECTIVE

A deficit of oligodendrocytes has been reported in the prefrontal cortex (PFC) in schizophrenia (SCH), bipolar disorder (BPD) and major depression (MDD). Also, a decreased size of pyramidal neurons has been detected in layer III in SCH and in mood disorders. Since oligodendrocytes have a trophic influence on neurons, reduced neuronal size reported in these disorders might be associated with the deficit in subpopulation of perineuronal oligodendrocytes. We hypothesized that deficit of perineuronal oligodendrocytes might occur in SCH and mood disorders.

METHOD

We estimated the number of oligodendroglial satellites of pyramidal neurons and the size of pyramidal neurons in layer III (Brodmann's area 9) in Nissl stained sections in SCH, BPD, MDD and normal controls. The Stanley Foundation Neuropathology Consortium brain collection consisted of 15 cases in each of four groups was used.

RESULTS

We detected a prominent and significant reduction in the number of perineuronal oligodendrocytes in the sublayers IIIa, IIIb and IIIc in SCH, BPD and MDD as compared to controls. The BPD group differed significantly from SCH group and from MDD group. There were no significant differences in somal sizes of pyramidal neurons in the sublayers IIIa, IIIb, IIIc between each of the psychiatric groups and the control group. Only BPD group showed significantly smaller neuronal size in sublayer IIIc as compared to controls.

CONCLUSIONS

Our data provide evidence for a deficit of perineuronal oligodendrocytes in severe mental disorders that may play a key role in the pathophysiology of SCH, BPD and MDD.

Novel alpha7 nicotinic receptor isoforms and deficient cholinergic transcription in schizophrenia

Abnormal alpha7 nicotinic acetylcholine receptor activity contributes to sensory gating and cognitive deficits in schizophrenic individuals. Negligible differences in alpha7 mRNA levels between disease and control states have led to conclusions that cholinergic dysfunction in schizophrenia (SZ) must occur post-transcriptionally. Alternatively, we propose that the dysregulation of splice variants of the alpha7 receptor could account for cholinergic deficiencies observed in this disease. Here, we isolated multiple alpha7 splice variants including exon deletions and those associated with a novel 124-127 base insertion following exon 4. Transcripts containing this new exon originated from sense strand-oriented RNA (vs. antisense), and in silico translations produced putative subunits with unique amino termini. Quantitative real-time polymerase chain reaction analyses indicated that one novel isoform was significantly downregulated (P < or = 0.03) in post-mortem prefrontal cortex of individuals with SZ (n = 35) compared with controls (n = 34). Ten brain regions (cerebellum, thalamus, corpus callosum, caudate, putamen and five areas of the cortex) were further screened for alpha7 isoforms in three individuals of each group. Semiquantitative analyses showed that each alpha7 mRNA subtype was present in each brain region, but all were particularly deficient in the corpus callosum in schizophrenics vs. controls (P < or = 0.0002 to 0.05 for different isoforms). Our data demonstrate that alpha7 transcription is altered in several ways in SZ, suggesting that transcription-level mechanisms could account in part for the impaired cholinergic neurotransmission observed in this disease.

Calprotectin in microglia from frontal cortex is up-regulated in schizophrenia: evidence for an inflammatory process?

Schizophrenia is associated with a number of pathological changes, including alterations in levels of specific proteins. Calprotectin is a novel 36 kDa calcium-binding protein of the S100 family and appears to be a nonspecific marker of inflammation. Calprotectin has not previously been investigated in brain tissue. Samples of post-mortem brain tissue from Brodmann area 9 were obtained from prefrontal cortex from subjects with schizophrenia, bipolar affective disorder, major depression, and from controls. Calprotectin levels were determined by ELISA. To determine cellular localization, immunocytochemical and fluorescent double-labelling analyses were performed. Exogenous calprotectin was added to retinoic acid-differentiated human SH-SY5Y neuroblastoma cell cultures in order to investigate mechanisms of action of calprotectin. Calprotectin was detectable in all samples, and mean levels were noted to be highest in schizophrenic brains (P < 0.05) and lowest in controls. Levels were intermediate in bipolar affective disorder and major depression. Exogenous calprotectin appeared to induce dendritic extension in SH-SY5Y cell culture in a dose-dependent manner. Calprotectin was found to be localized to microglia. These findings suggest that increased levels of calprotecitn in the brain may reflect inflammatory processes, which play a role in the pathogenesis of major psychiatric disorders. Furthermore, calprotectin may influence dendritic plasticity.

Schizophrenia, autoimmunity and immune system dysregulation: A comprehensive model updated and revisited

Recent investigation suggests a strong relationship between immunological effects and the pathophysiology of schizophrenia. Two prevalent approaches exist to this association. First, is more empirical a-priori research investigating immunological changes prevalent in schizophrenia and the second approach is more hypothesis-driven with analysis of immunological changes in schizophrenia based on known irregularities of the illness. The former approach is based upon three predominant lines of investigation including observations of a diffuse non-specific overactivation of the immunological response system, of a T-helper cell type 1 immune activation and of a T-helper cell type 2 immune activation in subgroups of schizophrenia patients. These last two theories suggest that a subgroup of patients with schizophrenia may demonstrate features of an autoimmune process, a theory supported by a growing database of investigation. The latter approach notes that many observations of immune dysregulation in schizophrenia overlap with central etiopathophysiological mechanisms as well as with clinical manifestations of the illness. Immunotherapy offers the opportunity to modify or re-balance the immune system and may become useful in management of the illness. Given that autoimmune mechanisms could interrupt neurotransmission, any process interfering with this disruption including therapeutic antibodies to involved cytokines, or with various other natural autoantibodies or immune system regulators, may become useful in the augmentative management of the illness.

Distribution of HLA-DR-positive microglia in schizophrenia reflects impaired cerebral lateralization

Immunological alterations have been demonstrated in peripheral blood and cerebrospinal fluid of patients with schizophrenia, while previous postmortem studies have provided an inconsistent picture as to the role of microglia in the context of schizophrenia. Microglial activation is a sensitive indicator of changes in the CNS microenvironment, such as inflammatory and neurodegenerative processes. The aim of the present postmortem study was to examine HLA class II (HLA-DR) expression on microglia in brain regions which are particularly relevant for schizophrenia, with regard to hemispheric lateralization. Dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), hippocampus and mediodorsal thalamus (MD) were studied in 16 cases with schizophrenia and 16 control subjects. Immunostaining was found in all brain regions and was not restricted to macrophage-like ameboid cells, but also appeared in ramified cells. Region-specific HLA-DR-positive cell density was not significantly different between cases with schizophrenia and controls. However, ameboid microglial cells were lateralized towards the right hemisphere in healthy subjects but not in the schizophrenia group (P=0.01). Postmortem interval correlated with ramified cell numbers in ACC/DLPFC (P=0.01/0.04) and ameboid cell density in hippocampus (P=0.03). Age, gender, duration of disease, medication dosage, storage delay and whole brain volume had no effect. Single case analysis revealed highly elevated microglial cell numbers in ACC and MD of two schizophrenic patients who had committed suicide during acute psychosis. In conclusion, the present data suggest the absence of microgliosis but decreased cerebral lateralization of ameboid microglia in schizophrenia.

Increased complement classical and mannan-binding lectin pathway activities in schizophrenia

Schizophrenia is a severe mental disorder, with worldwide prevalence of 1-1.5%. Immunological research in schizophrenia indicates that infectious or autoimmune processes might play a role in the etiopathogenesis. The complement system is a major mediator of innate immune defence against infection and contributes to many functions of the immune system including inflammation, opsonization and cell lysis. Mannan-binding lectin (MBL) activates the complement system via the lectin pathway. Inherited MBL deficiency, common in most human populations, predisposes to infectious and autoimmune diseases. We measured total complement activity (CH50), C4 activity (C4 CH50), MBL level and the activities of MBL-associated serine proteases, MASP-1 and MASP-2 in sera of 45 schizophrenic patients and in 62 healthy volunteers. We found that schizophrenic patients and healthy volunteers have statistically similar MBL levels and MASP-1 activity. However, MBL-bound MASP-2 activity and therefore MBL and MASP-2-mediated complement activation capacity is increased in schizophrenic patients compared with healthy volunteers (P<0.01). The increase was accompanied by increased CH50 (P<0.02) and C4 CH50 (P<0.02). Our results support the idea that complement system alterations may be involved in schizophrenia.

Glial fibrillary acidic protein and glutamine synthetase in subregions of prefrontal cortex in schizophrenia and mood disorder

Several theories of schizophrenia suggest dysfunction in glutamate neurotransmission in higher brain regions such as the prefrontal cortex (PFC). Previous studies have investigated whether astroglial abnormalities could give rise to glutamate dysfunction using glial fibrillary acidic protein (GFAP) immunocytochemistry. We have used quantitative immunoautoradiography to measure glutamine synthetase (GS), the glial enzyme which recycles synaptic glutamate, as a more direct test of glial mechanisms of abnormal glutamate function in schizophrenia. We compared GS with GFAP immunoautoradiography in dorsolateral (area 9) and orbitofrontal (area 11/47) cortex. Optical density measures from film autoradiographs revealed an increase in GFAP immunoreactivity in area 9 in schizophrenia and a decrease in area 11/47 in both schizophrenia and bipolar disorder. The increase in GFAP in area 9 significantly correlated with lifetime antipsychotic drug treatment, whereas the reduction in area 11/47 occurred despite this effect. There were no changes in GS immunoreactivity in any psychiatric disorder. Regional and antigen-specific down-regulation of GFAP protein in OFC in schizophrenia and bipolar disorder may relate to disease mechanisms of psychosis.

Recent progress in animal modeling of immune inflammatory processes in schizophrenia: implication of specific cytokines

Epidemiologic studies demonstrate significant environmental impact of maternal viral infection and obstetric complications on the risk of schizophrenia and indicate their detrimental influences on brain development in this disorder. Based on these findings, animal models for schizophrenia have been established using double stranded RNA, bacterial lipopolysaccharides, hippocampal lesion, or prenatal/perinatal ischemia. Key molecules regulating such immune/inflammatory reactions are cytokines, which are also involved in brain development, regulating dopaminergic and GABAergic differentiation, and synaptic maturation. Specific members of the cytokine family, such as interleukin-1, epidermal growth factor, and neuregulin-1, are induced after infection and brain injury; therefore, certain cytokines are postulated to have a central role in the neurodevelopmental defects of schizophrenia. Recently, to test this hypothesis, a variety of cytokines were administered to rodent pups. Cytokines administered in the periphery penetrated the immature blood-brain barrier and perturbed phenotypic neural development. Among the many cytokines examined, epidermal growth factor (or potentially other ErbB1 ligands) and interleukin-1 specifically induced the most severe and persistent behavioral and cognitive abnormalities, most of which were ameliorated by antipsychotics. These animal experiments illustrate that, during early development, these cytokine activities in the periphery perturbs normal brain development and impairs later psychobehavioral and/or cognitive traits. The neurodevelopmental and behavioral consequences of prenatal/perinatal cytokine activity are compared with those of other schizophrenia models and cytokine interactions with genes are also discussed in this review.

Atypical antipsychotics and a Src kinase inhibitor (PP1) prevent cortical injury produced by the psychomimetic, noncompetitive NMDA receptor antagonist MK-801

Noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonists such as phencyclidine, ketamine, and MK-801 produce schizophrenia-like psychosis in humans. The same NMDA antagonists injure retrosplenial cortical neurons in adult rats. We examined the effects of atypical antipsychotics and an inhibitor of nonreceptor tyrosine kinase pp60 (Src) on the cortical injury produced by MK-801. An atypical antipsychotic (either clozapine, ziprasidone, olanzapine, quetiapine, or risperidone) or vehicle was administered to adult female Sprague-Dawley rats. PP1 (Src inhibitor), PP3 (nonfunctional analog of PP1) or vehicle (DMSO) was administered to another group of animals. After pretreatment, animals were injected with MK-801, killed 24 h after the MK-801, and injury to retrosplenial cortex assessed by neuronal Hsp70 protein expression. All atypical antipsychotics examined significantly attenuated MK-801-induced cortical damage. PP1 protected compared to vehicle, whereas PP3 did not protect. The ED50s (decrease injury by 50%) were as follows: PP1 <0.1 mg/kg; olanzapine 0.8 mg/kg; risperdal 1 mg/kg; clozapine 3 mg/kg; ziprasidone 32 mg/kg; and quetiapine 45 mg/kg. The data show that the atypical antipsychotics tested as well as a Src kinase inhibitor prevent the injury produced by the psychomimetic MK-801, and the potency of the atypical antipsychotics for preventing cortical injury was roughly similar to the potency of these drugs for treating psychosis in patients.

Decreased numerical density of kainate receptor-positive neurons in the orbitofrontal cortex of chronic schizophrenics

We utilised postmortem brain tissue to quantify sections of left and right orbitofrontal cortex (area 11) from nine schizophrenic and eight control patients from the Charing Cross Prospective Schizophrenia Study immunostained for the presence of the kainate receptor (GluR5/6/7). The numerical density of neurons immunopositive for kainate receptor was measured. Other sections from the same blocks were stained with cresyl violet to determine the total neuronal numerical density. All measurements were made blind: diagnoses were only revealed by a third party after measurements were completed. There was a significant reduction (21%) in numerical density of kainate receptor-positive neurons in both cortices in the schizophrenic group (488 cells/mm2) compared to that in the control group (618 cells/mm2) (P=0.033). Nissl-stained tissue showed no significant difference in total neuronal numerical density between control and schizophrenic groups. These observations suggest that there are actually fewer kainate receptor-positive neurons in schizophrenic orbitofrontal cortex. There was no correlation of reduced kainate receptor-positive cell number with age at death, postmortem interval, or other possibly confounding neuropathology. Our results support the concept of there being reduced glutamatergic activity in frontal cortex in schizophrenia.

Glial fibrillary acidic protein is elevated in superior frontal, parietal and cerebellar cortices of autistic subjects

Autism is a debilitating neurodevelopmental disorder of early childhood with both genetic and environmental origins. Immune system dysregulation has been hypothesized to be involved in this disorder. We quantified levels of glial fibrillary acidic protein (GFAP) and ss-actin in three areas of the brain, namely, area 9, area 40 and cerebellum, in age matched autistic and control postmortem specimen using SDS-PAGE and western blotting techniques. Significant elevations in levels of GFAP were observed in all three brain areas in autism. This report confirms a recent report showing microglial and astroglial activation in autism. Increased GFAP levels in autistic brains signify gliosis, reactive injury, and perturbed neuronal migration processes.

Increased serum interleukin-1beta and interleukin-6 in elderly, chronic schizophrenic patients on stable antipsychotic medication

In schizophrenia, alterations of proinflammatory cytokine levels have been reported and related to the disease and psychopathology. However, only limited conclusions can be drawn in view of confounding factors such as infection, age, sex, smoking, and antipsychotic medication. Chronic schizophrenic patients with a long-term disease process and medication period have not been investigated so far. We have measured serum levels of interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)alpha in 41 elderly, chronic schizophrenic patients and 23 age- and sex-matched controls using enzyme-linked immunosorbent assay (ELISA). We assessed detailed psychopathology and neuropsychological performance and determined serum levels of haloperidol, clozapine, and the two main clozapine metabolites, desmethylclozapine and clozapine metabolite N-oxide, by high-pressure liquid chromatography (HPLC). IL-1beta and IL-6 levels were increased in treatment-resistant schizophrenic patients compared with healthy controls, whereas TNFalpha showed no difference. We did not find statistically significant differences of cytokine levels between medication groups and there was no correlation with serum levels of antipsychotics or psychopathological rating scores. Elevations of IL-1beta and IL-6 in elderly chronic schizophrenic patients may be related to an active disease process lasting until old age. Despite missing correlations, long-term treatment effects in treatment-resistant patients may have affected TNFalpha, leading to control levels. Post-mortem and animal studies should clarify the presence of altered immune function in the brain as well as the effect of cytokine levels in relation to neurodevelopmental disturbances and schizophrenia-associated behavior.

Glial fibrillary acidic protein mRNA levels in the cingulate cortex of individuals with depression, bipolar disorder and schizophrenia

Recent studies have shown a decrease in glial number and glial fibrillary acidic protein (GFAP) levels in the frontal and cingulate cortices of individuals with mood disorders and schizophrenia. In an attempt to verify and expand these findings we examined GFAP messenger ribonucleic acid (mRNA) levels in postmortem sections of the anterior cingulate cortex (ACC) from the Stanley Neuropathology Consortium (SNC). The consortium consists of 15 cases in each of four groups (schizophrenia, bipolar disorder, non-psychotic depression and unaffected controls). By in situ hybridization, we found higher levels of GFAP mRNA in white matter and at the pial surface as compared with gray matter levels in all cases. In the white matter of ACC we detected a significant effect of diagnosis (P<0.04) with GFAP mRNA levels decreased in individuals with schizophrenia and bipolar disorder as compared with normal controls. In the gray matter there was a significant effect of layer (P<0.01) with the highest levels of GFAP mRNA in layer VI in all groups. As in the white matter, the mean GFAP mRNA levels were decreased in individuals with schizophrenia and bipolar disorder as compared with the unaffected controls, however the difference failed to reach statistical significance. Thus, astrocytes positive for GFAP may contribute to the decrease in glial density previously described in subjects with major mental illness, however the relative contribution of astrocytes may vary with diagnosis.

Mapping cortical thickness and gray matter concentration in first episode schizophrenia

We mapped regional changes in cortical thickness and intensity-based cortical gray matter concentration in first episode schizophrenia. High-resolution magnetic resonance images were obtained from 72 (51 male, 21 female) first episode patients and 78 (37 male, 41 female) healthy subjects similar in age. Cortical pattern matching methods allowed comparisons of cortical thickness and gray matter concentration at thousands of homologous cortical locations between subjects in three dimensions. Principal components analyses reduced measures obtained across the cortex to identify global differences in cortical thickness/gray matter concentration. First principal component factor scores showed significant effects of diagnosis, sex and age for both cortical measures. Diagnosis and age effects remained significant after brain size correction. Cortical thickness and gray matter concentration values were highly correlated. Statistical maps showed significant regional gray matter thinning in frontal, temporal and parietal heteromodal association cortices bilaterally in first episode patients. Regional reductions in cortical gray matter concentration were similar but pronounced in the superior temporal lobe. Regional reductions in cortical thickness and gray matter concentration are present at disease onset in brain regions linked with functional disturbances in schizophrenia. Cortical thickness and gray matter concentration mapping produce similar results, although the concentration metric may be influenced by diagnostic differences in extra-cortical cerebrospinal fluid and surface curvature/complexity.

Near-infrared spectroscopy analysis of frontal lobe dysfunction in schizophrenia

BACKGROUND

Previous studies have shown that near-infrared spectroscopy (NIRS) has high temporal resolution, requires little restraint, and is suitable for examining the effect of psychological tasks on brain circulation. In the present study, frontal function in schizophrenic patients was analyzed by NIRS during random number generation (RNG), ruler-catching (RC), and sequential finger-to-thumb (SFT) tasks.

METHODS

Two sets of NIRS probes were attached to the foreheads of 13 schizophrenic patients and 10 control subjects approximately at Fp1-F7 and Fp2-F8. Near-infrared spectroscopy was conducted at a sampling rate of 1 Hz, with the pathlength being determined by time-resolved spectroscopy with differential pathlength factor measurements. The absolute changes in oxygenated (oxy-Hb) and deoxygenated (deoxy-Hb) hemoglobin concentrations in response to each task were measured, and total hemoglobin (total-Hb) concentration was calculated as the sum of the two.

RESULTS

During RNG task, total- and oxy-Hb concentrations increased, and deoxy-Hb decreased, but the responses were significantly smaller in schizophrenic patients. During RC task, oxy-Hb in schizophrenic patients tended to decrease, in contrast to the mostly increasing response in control subjects. No group difference was observed during SFT task.

CONCLUSIONS

Task-dependent profile of functional abnormalities was observed in schizophrenic frontal brain metabolism. These results support the usefulness of NIRS data in investigating frontal lobe dysfunction and evaluating psychopathologic condition in schizophrenic patients.

Antibodies against astrocyte M1and M2muscarinic cholinoceptor from schizophrenic patients' sera

We demonstrated the presence of circulating antibodies from schizophrenic patients able to interact with cultured astrocytes activating muscarinic acetylcholine receptors (mAChRs). Sera and purified IgG from 15 paranoid schizophrenic and 15 age-matched normal subjects were studied by indirect immunofluorescence (IFI), flow cytometry, dot blot, enzyme immunoassay (ELISA), and radioligand competition assays. Astrocyte membranes and/or a synthetic peptide, with identical amino acid sequence of human M(1) and M(2) mAChR, were used as antigens. By IFI and flow cytometry procedures, we proved that serum purified IgG fraction from schizophrenic patients, reacted to astrocyte cell surface. The same antibodies were able to inhibit the binding of the specific mAChR radioligand (3)H-QNB. Using synthetic peptide for dot blot and ELISA, we demonstrated that these antibodies reacted against the second extracellular loop of human cerebral M(1) and M(2) mAChR. Also, the corresponding affinity-purified antipeptide antibody displayed an agonistic-like activity associated to specific M(1) and M(2) mAChR activation, increasing inositol phosphates accumulation and decreasing cyclic AMP production, respectively. This article gives support to the participation of an autoimmune process in schizophrenia disease.

A decrease in interleukin-1 receptor antagonist expression in the prefrontal cortex of schizophrenic patients

Interleukin-1 (IL-1) mediates psychological stress responses by regulating monoamine metabolism and secretion of corticotropin-releasing factor, and is therefore, implicated in various psychiatric diseases. To evaluate the contribution of IL-1 signaling to the brain pathology of schizophrenia, we measured protein and/or mRNA levels for IL-1beta and endogenous IL-1 receptor antagonist (IL-1RA) in the postmortem brain tissues of prefrontal and parietal cortex, putamen, and hypothalamus. Both protein and mRNA levels of IL-1RA were specifically decreased in the prefrontal cortex of schizophrenic patients, whereas IL-1beta levels were not significantly altered in all the regions examined. The IL-1RA decrease was not correlated with the dose of antipsychotics given to patients. There was no influence of this illness on protein levels for IL-1 receptor type 1 in the prefrontal cortex, either. In contrast, IL-1RA serum levels were increased in schizophrenic patients, especially in drug-free patients, as reported previously. These findings suggest that chronic schizophrenia down-regulates IL-1RA production the prefrontal cortex, irrespective of its impact on the periphery. IL-1RA reduction might reflect an immunopathologic trait of the prefrontal region in schizophrenic patients.

Human influenza viral infection in utero alters glial fibrillary acidic protein immunoreactivity in the developing brains of neonatal mice

Epidemiological reports describe a strong association between prenatal human influenza viral infection and later development of schizophrenia. Postmodern human brain studies, however, indicate a lack of gliosis in schizophrenic brains presumably secondary to absence of glial cells during the second trimester viral infection in utero. We hypothesized that human influenza infection in day 9 pregnant mice would alter the expression of glial fibrillary acidic protein (GFAP, an important marker of gliosis, neuron migration, and reactive injury) in developing brains of postnatal days 0, 14 and 35 mice. Determination of cellular GFAP immunoreactivity (IR) expressed as cell density in cortex and hippocampus of control and experimental brains showed increases in GFAP-positive density in exposed cortical (P = 0.03 day 14 vs control) and hippocampal cells (P = 0.035 day 14, P = 0.034 day 35). Similarly, ependymal cell layer GFAP-IR cell counts showed increases with increasing brain age from day 0, to days 14 and 35 in infected groups (P = 0.037, day 14) vs controls. The GFAP-positive cells in prenatally exposed brains showed 'hypertrophy' and more stellate morphology. These results implicate a significant role of prenatal human influenza viral infection on subsequent gliosis, which persists throughout brain development in mice from birth to adolescence.

Prefrontal-posterior parietal networks in schizophrenia: primary dysfunctions and secondary compensations

BACKGROUND

Working memory (WM) deficits are well known in schizophrenia and have been associated with abnormal activation patterns of the prefrontal cortex (PFC) during cognitive performance. The magnitude and particularly the direction of the PFC activation -- i.e., increased (hyperfrontality) or decreased (hypofrontality) -- in schizophrenia, as well as its pathophysiological implications, remain controversial. Working memory is supported by a distributed neural network, whose main components are the PFC and the posterior parietal (PPC) cortices. Monkey studies indicate that, during WM performance, PFC functional lesions may be compensated by the PPC if task demands center mainly on anticipating responses, but not if they center on remembering cues. We hypothesized that a primarily dysfunctional PFC in schizophrenia might show hypofrontality or hyperfrontality as a result, respectively, of efficient or inefficient PPC compensation, as dictated by task demands. To test our proposition, we biased the demands of WM tasks toward anticipating responses or remembering cues and measured its impact on the PFC-PPC functional balance in a group of schizophrenic patients and one of normal control subjects.

METHODS

We used functional magnetic resonance imaging to measure correlates of neuronal activity in the PFC and PPC of schizophrenic patients and control subjects performing WM tasks that either demanded information retention or allowed for response anticipation.

RESULTS

When compared to control subjects, schizophrenic patients exhibited decreased PFC activation and increased PPC activation during anticipatory WM performance, and increased PFC activation during mnemonic WM performance.

CONCLUSIONS

In schizophrenia, a PFC dysfunction results in hypo- or hyperfrontality as a function of whether other alternate areas of a PFC-PPC network for WM are available and efficacious in supporting specific task demands.

Layer-specific reductions in GFAP-reactive astroglia in the dorsolateral prefrontal cortex in schizophrenia

Neuroimaging studies have implicated the prefronto-striatal loop as a substrate for the cognitive deficits in schizophrenia (SCHZ). Postmortem morphometric studies reveal that layers III and V of the dorsolateral prefrontal cortex (dlPFC), which gave rise to glutamatergic projections to neostriatum, demonstrate the most structural pathology in this region of the SCHZ. These neuronal alterations in SCHZ are not accompanied by marked glial changes as revealed by Nissl staining. We examined the glial-type specific pathology in SCHZ by analyzing the glial fibrillary acidic protein- (GFAP) immunoreactive astroglia in contrast to the Nissl-stained general pool of glial cells in dlPFC (area 9) from 9 subjects with SCHZ and 15 psychiatrically normal control subjects. In layer V of the dlPFC in SCHZ, there was a significant 32% reduction in the GFAP-area fraction, 81% increase in the density of the GFAP-positive cell bodies and a 14% decrease in the width of the cortical layer V, as compared to the control subjects. None of these parameters were affected in layers III and IV in the SCHZ. Therefore, only subtle, type- and layer-specific glial pathology is present in the dlPFC in SCHZ. Astroglial pathology in dlPFC may reflect disturbances of the neuron-glia interactions in layer V and may be related to the dysfunctional prefronto-striatal circuits, dopaminergic alterations and cognitive pathology in SCHZ.

Review of immunological and immunopathological findings in schizophrenia

The involvement of immunological and immunopathological mechanisms in the etiopathogenesis of schizophrenia has been a matter of research, with recently increasing effort. This article reviews the findings focusing on postmortem neuropathology, the blood-brain barrier, antibodies, acute phase proteins, immunocompetent cells, and activation markers of immunocompetent cells. Evidence for the two primarily postulated hypotheses (the infectious hypothesis and the autoimmune hypothesis) is critically discussed. On the basis of the findings, perspectives for future research are outlined aiming at a precise and consequent strategy to elucidate a potential involvement of immune mechanisms in the etiopathogenesis of schizophrenia.

Immunohistochemical localization of phosphorylated glial fibrillary acidic protein in the prefrontal cortex and hippocampus from patients with schizophrenia, bipolar disorder, and depression

Increasingly, abnormalities of glial cell function have been implicated in pathological studies of the major mental illnesses (schizophrenia, bipolar disorder, and major depression). In a recent proteomic study, four isoforms of astrocytic glial fibrillary acidic protein (GFAP) were decreased in one or more of these diseases. In the current study, we sought to determine the immunohistochemical localization of phosphorylated GFAP (pGFAP) in the prefrontal cortex and hippocampus and to describe possible disease-related changes in the distribution of pGFAP containing astrocytes. In the prefrontal cortex, interlaminar astrocytes in layer I and stellate astrocytes in layers II and VI were labeled. Labeled cells were also present adjacent to blood vessels in the gyral white matter and in underlying white matter generally. In the hippocampus, labeled cells were present in the polymorphic layer of the dentate gyrus. In the prefrontal cortex, schizophrenia and major depression were characterized by decreased labeling of astrocytes adjacent to blood vessels. There were no significant differences between the diagnostic groups in the other prefrontal layers or in the hippocampus. These results suggest that reduced numbers or functional regulation of pGFAP containing astrocytes occurs in schizophrenia and major depression. The mechanism by which this deficit occurs is not known, but it may adversely effect the regulation of neuronal metabolism, communication, and response to injury.

Glial cell abnormalities in major psychiatric disorders: the evidence and implications

Recent quantitative post-mortem investigations of the cerebral cortex have convincingly demonstrated cortical glial cell loss in subjects with major depression. Evidence is also mounting that glial cell loss may also be a feature of schizophrenia. These findings coincide with a re-evaluation of the importance of glial cells in normal cortical function. In addition to their traditional roles in neuronal migration and inflammatory processes, glia are now accepted to have roles in providing trophic support to neurons, neuronal metabolism, and the formation of synapses and neurotransmission. Consequently, reduced cortical glial cell numbers could be responsible for some of the pathological changes in schizophrenia and depression, including reduced neuronal size, reduced levels of synaptic proteins, and abnormalities of cortical neurotransmission. Additionally, as astrocytes provide the energy requirements of neurons, deficient astrocyte function could account for aspects of the functional magnetic imaging abnormalities found in these disorders. We discuss the possible basis of glial cell loss in these disorders and suggest that elevated levels of glucocorticoids, due to illness-related stress or to hyperactivity of the hypothalamic-pituitary-adrenal may down-regulate glial activity and so predispose to, or exacerbate psychiatric illness through enhanced excitotoxicity. The potential therapeutic impact of agents which up-regulate glial activity or normalise glial cell numbers is also discussed.

Electron microscopy of oligodendroglia in severe mental illness

Qualitative electron microscopy was performed to verify whether brain pathology in schizophrenia and bipolar disorder is associated with alterations of oligodendroglial cells and myelinated fibers. Ultrastructural signs of apoptosis and necrosis of oligodendroglial cells were found in the prefrontal area 10 and the caudate nucleus in both schizophrenia and bipolar disorder. Damage of myelin sheath lamellae, with the formation of concentric lamellar bodies, were detected in both brain structures in schizophrenia. There was also a significant decrease in the area of the nucleus and the volume density of mitochondria in oligodendrogliocytes in the caudate nucleus and in the prefrontal cortex in schizophrenia, as compared to normal controls. Volume density of heterochromatin was significantly increased (+14%) in the caudate nucleus in schizophrenia. The density of concentric lamellar bodies (as an indicator of damage of myelinated fibers) was dramatically increased (4.5-fold) in the caudate nucleus in schizophrenia, as compared to controls, and was positively correlated with volume density of heterochromatin. Multiple regression analysis and analysis of covariance demonstrated that these changes could not be explained by the effects of postmortem delay, age, neuroleptic medication, or gender. Pathology of oligodendroglia might be an essential feature of severe mental disorders.

Early and progressive accumulation of reactive microglia in the Huntington disease brain

Microglia may contribute to cell death in neurodegenerative diseases. We studied the activation of microglia in affected regions of Huntington disease (HD) brain by localizing thymosin beta-4 (Tbeta4), which is increased in reactive microglia. Activated microglia appeared in the neostriatum, cortex, and globus pallidus and the adjoining white matter of the HD brain, but not in control brain. In the striatum and cortex, reactive microglia occurred in all grades of pathology, accumulated with increasing grade, and grew in density in relation to degree of neuronal loss. The predominant morphology of activated microglia differed in the striatum and cortex. Processes of reactive microglia were conspicuous in low-grade HD, suggesting an early microglia response to changes in neuropil and axons and in the grade 2 and grade 3 cortex, were aligned with the apical dendrites of pyramidal neurons. Some reactive microglia contacted pyramidal neurons with huntingtin-positive nuclear inclusions. The early and proximate association of activated microglia with degenerating neurons in the HD brain implicates a role for activated microglia in HD pathogenesis.