Brain antibodies in the cortex and blood of people with schizophrenia and controls.

The immune system is implicated in the pathogenesis of schizophrenia, with elevated proinflammatory cytokine mRNAs found in the brains of ~40% of individuals with the disorder. However, it is not clear if antibodies (specifically immunoglobulin-γ (IgG)) can be found in the brain of people with schizophrenia and if their abundance relates to brain inflammatory cytokine mRNA levels. Therefore, we investigated the localization and abundance of IgG in the frontal cortex of people with schizophrenia and controls, and the impact of proinflammatory cytokine status on IgG abundance in these groups. Brain IgGs were detected surrounding blood vessels in the human and non-human primate frontal cortex by immunohistochemistry. IgG levels did not differ significantly between schizophrenia cases and controls, or between schizophrenia cases in 'high' and 'low' proinflammatory cytokine subgroups. Consistent with the existence of IgG in the parenchyma of human brain, mRNA and protein of the IgG transporter (FcGRT) were present in the brain, and did not differ according to diagnosis or inflammatory status. Finally, brain-reactive antibody presence and abundance was investigated in the blood of living people. The plasma of living schizophrenia patients and healthy controls contained antibodies that displayed positive binding to Rhesus macaque cerebellar tissue, and the abundance of these antibodies was significantly lower in patients than controls. These findings suggest that antibodies in the brain and brain-reactive antibodies in the blood are present under normal circumstances.

Genome-wide supported variant MIR137 and severe negative symptoms predict membership of an impaired cognitive subtype of schizophrenia.

Progress in determining the aetiology of schizophrenia (Sz) has arguably been limited by a poorly defined phenotype. We sought to delineate empirically derived cognitive subtypes of Sz to investigate the association of a genetic variant identified in a recent genome-wide association study with specific phenotypic characteristics of Sz. We applied Grade of Membership (GoM) analyses to 617 patients meeting ICD-10 criteria for Sz (n=526) or schizoaffective disorder (n=91), using cognitive performance indicators collected within the Australian Schizophrenia Research Bank. Cognitive variables included subscales from the Repeatable Battery for the Assessment of Neuropsychological Status, the Controlled Oral Word Association Test and the Letter Number Sequencing Test, and standardised estimates of premorbid and current intelligence quotient. The most parsimonious GoM solution yielded two subtypes of clinical cases reflecting those with cognitive deficits (CDs; N=294), comprising 47.6% of the sample who were impaired across all cognitive measures, and a cognitively spared group (CS; N=323) made up of the remaining 52.4% who performed relatively well on all cognitive tests. The CD subgroup were more likely to be unemployed, had an earlier illness onset, and greater severity of functional disability and negative symptoms than the CS group. Risk alleles on the MIR137 single-nucleotide polymorphism (SNP) predicted membership of CD subtype only in combination with higher severity of negative symptoms. These findings provide the first evidence for association of the MIR137 SNP with a specific Sz phenotype characterised by severe CDs and negative symptoms, consistent with the emerging role of microRNAs in the regulation of proteins responsible for neural development and function.

Imprinted DLK1-DIO3 region of 14q32 defines a schizophrenia-associated miRNA signature in peripheral blood mononuclear cells.

MicroRNAs (miRNAs) regulate gene expression at the post-transcriptional level and are important for coordinating nervous system development and neuronal function in the mature brain. We have recently identified schizophrenia-associated alteration of cortical miRNA biogenesis and expression in post-mortem brain tissue with implications for the dysregulation of schizophrenia candidate genes. Although these changes were observed in the central nervous system, it is plausible that schizophrenia-associated miRNA expression signatures may also be detected in non-neural tissue. To explore this possibility, we investigated the miRNA expression profile of peripheral blood mononuclear cells (PBMCs) from 112 patients with schizophrenia and 76 non-psychiatric controls. miRNA expression analysis of total RNA conducted using commercial miRNA arrays revealed that 33 miRNAs were significantly downregulated after correction for multiple testing with a false discovery rate (FDR) of 0%, which increased to 83 when we considered miRNA with an FDR<5%. Seven miRNAs altered in microarray analysis of schizophrenia were also confirmed to be downregulated by quantitative real-time reverse transcription-polymerase chain reaction. A large subgroup consisting of 17 downregulated miRNAs is transcribed from a single imprinted locus at the maternally expressed DLK1-DIO3 region on chromosome 14q32. This pattern of differentially expressed miRNA in PBMCs may be indicative of significant underlying genetic or epigenetic alteration associated with schizophrenia.

Gray matter deficits, mismatch negativity, and outcomes in schizophrenia.

Reduced mismatch negativity (MMN) in response to auditory change is a well-established finding in schizophrenia and has been shown to be correlated with impaired daily functioning, rather than with hallmark signs and symptoms of the disorder. In this study, we investigated (1) whether the relationship between reduced MMN and impaired daily functioning is mediated by cortical volume loss in temporal and frontal brain regions in schizophrenia and (2) whether this relationship varies with the type of auditory deviant generating MMN. MMN in response to duration, frequency, and intensity deviants was recorded from 18 schizophrenia subjects and 18 pairwise age- and gender-matched healthy subjects. Patients' levels of global functioning were rated on the Social and Occupational Functioning Assessment Scale. High-resolution structural magnetic resonance scans were acquired to generate average cerebral cortex and temporal lobe models using cortical pattern matching. This technique allows accurate statistical comparison and averaging of cortical measures across subjects, despite wide variations in gyral patterns. MMN amplitude was reduced in schizophrenia patients and correlated with their impaired day-to-day function level. Only in patients, bilateral gray matter reduction in Heschl's gyrus, as well as motor and executive regions of the frontal cortex, correlated with reduced MMN amplitude in response to frequency deviants, while reduced gray matter in right Heschl's gyrus also correlated with reduced MMN to duration deviants. Our findings further support the importance of MMN reduction in schizophrenia by linking frontotemporal cerebral gray matter pathology to an automatically generated event-related potential index of daily functioning.

Schizophrenia is associated with an increase in cortical microRNA biogenesis.

MicroRNA expression profiling and quantitative reverse transcription-PCR analysis of the superior temporal gyrus and the dorsolateral prefrontal cortex revealed a significant schizophrenia-associated increase in global microRNA expression. This change was associated with an elevation of primary microRNA processing and corresponded with an increase in the microprocessor component DGCR8. The biological implications for this extensive increase in gene silencing are profound, and were exemplified by members of the miR-15 family and other related microRNA, which were significantly upregulated in both brain regions. This functionally convergent influence is overrepresented in pathways involved in synaptic plasticity and includes many genes and pathways associated with schizophrenia, some of which were substantiated in vitro by reporter gene assay. Given the magnitude of microRNA changes and their wide sphere of influence, this phenomenon could represent an important dimension in the pathogenesis of schizophrenia.

Increased tachykinin NK(1) receptor immunoreactivity in the prefrontal cortex in schizophrenia.

BACKGROUND: Changes in levels of substance P and substance P-binding sites have been implicated in schizophrenia. However, no studies have used receptor-specific antibodies to directly investigate the substance P (neurokinin 1) receptor in schizophrenia. METHODS: We used an antibody directed against the human neurokinin-1 receptor to compare the distribution of neurokinin-1 receptors in the prefrontal cortices from six subjects with schizophrenia and six control subjects, matched for age, gender, and postmortem interval. RESULTS: In control tissue, dots of neurokinin-1 receptor immunoreactivity were observed in layer I to upper/mid layer III only. In contrast, dots of neurokinin-1 receptor immunoreactivity were observed in all layers of the prefrontal cortex in subjects with schizophrenia, and the density of dots was significantly greater than in control subjects. CONCLUSIONS: This is the first report of increased neurokinin-1 receptor immunoreactivity in the prefrontal cortex in subjects with schizophrenia. These changes may have implications for understanding the pathophysiology of the prefrontal cortex in schizophrenia and for the treatment of this disorder.

Tachykinin NK1 and NK3 receptors in the prefrontal cortex of the human brain.

1. The tachykinins are neuropeptides found in both the central and peripheral nervous systems that play a role in inflammation and pain mechanisms and some autonomic reflexes and behaviours. 2. Although the distribution of the tachykinin receptors has been described in the brains of various animal species, little is known about the distribution of the NK1 and NK3 receptors in the human brain. 3. The present paper examines the distribution of the NK1 and NK3 receptors in the prefrontal cortex of formalin-fixed postmortem human brain tissue by immunohistochemical techniques. 4. The majority of NK1 receptor immunoreactivity appeared as a thin band of punctate staining at the pial surface, with dark brown dots of NK1 receptor immunoreactivity predominantly scattered across the mid to upper cortical layers. 5. The NK3 receptor immunoreactivity was found in the glia limitans at the pial surface, where astrocytes and beaded fibres were intensely stained. Dots of NK3 receptor immunoreactivity were scattered across all cortical layers. In the white matter, astrocytes and beaded fibres displayed NK3 receptor immunoreactivity, particularly in areas surrounding blood vessels.

Localisation of tachykinin NK1 and NK3 receptors in the human prefrontal and visual cortex.

The distribution of tachykinin NK(1) and NK(3) receptors in the prefrontal (Brodmann area 9) and visual cortex (Brodmann area 17) of formalin-fixed postmortem human brain tissue was studied by immunohistochemistry. NK(1)-like immunoreactivity (NK(1)-LI) was observed as a thin band at the cortical surface and dots of NK(1)-LI localised on small non-pyramidal cells and in the neuropil (layers I-III). NK(3)-LI was found in beaded fibres and cells with astrocyte-like morphology in the superficial cortical layers and white matter. Dots of NK(3)-LI were prominent in the neuropil and on pyramidal (layers III/V) and non-pyramidal (layers V/VI) cells. The NK(3)-LI was more abundant and widespread than the NK(1)-LI. This is the first report of the distribution of the NK(1) receptor in the prefrontal and visual cortex of the human brain by immunohistochemistry.

Restricted localization of thrombospondin-2 protein during mouse embryogenesis: a comparison to thrombospondin-1.

Thrombospondin-1 and -2 (TSP1 and TSP2) are multifunctional, multimodular extracellular matrix proteins encoded by separate genes. We compared the distributions of TSP1 and TSP2 in mouse embryos (day 10 and later) by immunohistochemistry. TSP1 was detected on day 10 in the heart and intestinal epithelium, on day 11 in megakaryocytes, and on day 14 in the lung. TSP2 was not detected until day 14, with strongest staining in mesenchymal condensation that gives rise to cartilage and bone. The distribution of TSP2 was different from but overlapped with the distribution of TSP1. TSP1 was found in cartilage proper with diminished staining around chondrocytes undergoing differentiation and hypertrophy, whereas TSP2 was restricted to the matrix surrounding chondrocytes of the growth zone cartilage. TSP2 and TSP1 were both expressed in centers of intramembranous ossification that form the skull bones, in reticular dermis, on the apical surface of nasal epithelium, in skeletal muscle, and in the sheath surrounding vibrissae. Areas of exclusive staining for TSP2 included the perichondrium surrounding the cartilage of the nasal cavities, developing bone of the lower mandible, and adrenal gland. The distinct localizations of TSP1 and TSP2 indicate that the two proteins have specific functions during mouse embryogenesis.

A re-examination of the molecular basis of cell movement.

A model for cell movement is presented. It is suggested that cells do not migrate on collagen using their VLA (very late antigen) integrins that bind this extracellular matrix protein. Rather, the cells utilize alpha v integrins to bind endogenously produced fibronectin, which binds to the underlying collagen. It is envisaged that cells proceed by a process of engagement and disengagement of alpha v integrins to the extracellular matrix, somewhat analogous to the motion of a monkey climbing a tree. Secretion of isoforms of the adhesion modulator, thrombospondin, regulates disengagement of the integrin from its ligand in migrating cells. The integrin disengagement signal is mediated by thrombospondin cross-linking the alpha v integrin to an integrin accessory molecule and thus activating protein kinases. The cross-linked receptor complex undergoes recycling back along actin stress fibres, guided by the integrin beta-subunit. After endocytosis and protein sorting the alpha v integrin is transported back to the leading edge off migrating cells in vesicles guided by the tubulin-binding capabilities of an integrin accessory molecule. Direct attachment to collagen required for processes, such as matrix contraction, is mediated by VLA integrins which displace alpha v integrins from points of attachment during integrin recycling, possibly through an alpha v beta 1 intermediary receptor.