Marjan A. Versnel

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.

The immune theory of psychiatric diseases : a key role for activated microglia and circulating monocytes

This review describes a key role for mononuclear phagocytes in the pathogenesis of major psychiatric disorders. There is accumulating evidence for activation of microglia (histopathology and PET scans) and circulating monocytes (enhanced gene expression of immune genes, an overproduction of monocyte/macrophage‐related cytokines) in patients with bipolar disorder, major depressive disorder, and schizophrenia. These data are strengthened by observations in animal models, such as the MIA models, the chronic stress models, and the NOD mouse model. In these animal models of depressive‐, anxiety‐, and schizophrenia‐like behavior, similar activations of microglia and circulating monocytes can be found. These animal models also make in‐depth pathogenic studies possible and show that microglia activation impacts neuronal development and function in brain areas congruent with the altered depressive and schizophrenia‐like behaviors.

Prevalence of interferon type I signature in CD14 monocytes of patients with Sjögren's syndrome and association with disease activity and BAFF gene expression

Objective To determine the prevalence of upregulation of interferon (IFN) type I inducible genes, the so called ‘IFN type I signature’, in CD14 monocytes in 69 patients with primary Sjögrens syndrome (pSS) and 44 healthy controls (HC) and correlate it with disease manifestations and expression of B cell activating factor (BAFF). Methods Expression of IFI44L, IFI44, IFIT3, LY6E and MX1 was measured using real time quantitative PCR in monocytes. Expression values were used to calculate IFN type I scores for each subject. pSS patients positive for the IFN type I signature (IFN score≥10) and patients negative for the signature (IFN score<10) were then compared for clinical disease manifestations and BAFF expression. A bioassay using a monocytic cell line was performed to study whether BAFF mRNA expression was inducible by IFN type I activity in serum of patients with pSS. Results An IFN type I signature was present in 55% of patients with pSS compared with 4.5% of HC. Patients with the IFN type I signature showed: (a) higher EULAR Sjögrens Syndrome Disease Activity Index scores; higher anti-Ro52, anti-Ro60 and anti-La autoantibodies; higher rheumatoid factor; higher serum IgG; lower C3, lower absolute lymphocyte and neutrophil counts; (b)higher BAFF gene expression in monocytes. In addition, serum of signature-positive patients induced BAFF gene expression in monocytes. Conclusions The monocyte IFN type I signature identifies a subgroup of patients with pSS with a higher clinical disease activity together with higher BAFF mRNA expression. Such patients might benefit from treatment blocking IFN type I production or activity.

Systemic increase in type I interferon activity in Sjögren's syndrome: a putative role for plasmacytoid dendritic cells

In the salivary glands of primary Sjögrens syndrome (pSjS) patients, type I IFN activity is increased, but systemic levels of type I IFN proteins are rarely detected. This study focused on the systemic activity of type I IFN in pSjS, as well as the role of peripheral plasmacytoid dendritic cells (pDC). Monocytes obtained from pSjS patients showed an increased expression of 40 genes. Twenty‐three of these genes (58%), including IFI27, IFITM1, IFIT3 and IFI44, were inducible by type I IFN. pSjS serum had an enhanced capability of inducing IFI27, IFITM1, IFIT3 and IFI44 in the monocytic cell line THP‐1, likely due to the action of IFN‐β. This effect could be inhibited by blocking the type I IFN receptor, supporting a high type I IFN bioactivity in pSjS serum. In addition, circulatory pDC showed increased expression of CD40. This expression was correlated to the expression level of the type I IFN‐regulated genes IFI27 and IFITM1 in monocytes of the same individual. This study indicates that the increased type I IFN activity observed in pSjS patients is not only a local but also a systemic phenomenon and points to pDC as a possible source of this activity.

An activated set point of T-cell and monocyte inflammatory networks in recent-onset schizophrenia patients involves both pro- and anti-inflammatory forces

We recently described a pro-inflammatory gene expression signature in the monocytes of 60% of patients with recent-onset schizophrenia (SCZ). Here we investigated whether the T-cell system is also in a pro-inflammatory state. A detailed fluorescence-activated cell sorting (FACS) analysis, e.g. of CD3+CD25+ T cells, IFN-γ+, IL-4+, IL-17A+ (CD4+) lymphocytes and CD4+CD25highFoxP3+ regulatory T cells, was performed on peripheral blood of 26 patients with recent-onset SCZ (in 19 of whom the inflammatory gene expression signature of the monocyte had been determined) and in age-/gender-matched healthy controls. Various relevant T-cell cytokines, e.g. sCD25, IFN-γ, IL-17A and IL-4, were measured in serum by a multiplex assay. We detected: (a) not only higher percentages of pro-inflammatory-prone monocytes, activated CD3+CD25+ T cells and pro-inflammatory Th17 cells in patients, but also higher percentages of anti-inflammatory CD4+CD25highFoxP3+ regulatory T cells and IL-4+ lymphocytes; (b) that this activated T-cell set point was reflected in significantly raised serum levels of sCD25; (c) that the up-regulation of IL-4+-containing lymphocytes was predominantly found in patients characterized by a monocyte pro-inflammatory set point; and (d) that regulatory T-cell and Th17-cell numbers were higher in patients irrespective of the pro-inflammatory state of the monocytes. Our data do not support the concept that the T-cell system is in a simple pro-inflammatory state in recent-onset SCZ, but do show that the monocyte and T-cell networks are activated and involve both pro- and anti-inflammatory forces. This suggests control within an activated inflammatory system.

Increased level of serum cytokines, chemokines and adipokines in patients with schizophrenia is associated with disease and metabolic syndrome

At present there are strong indications of a shared vulnerability factor for schizophrenia (SZ), diabetes and the metabolic syndrome (metS). In this study we focus on an aberrantly activated monocyte/macrophage system as the shared factor. We measured in SZ patients (n=144), the serum levels of monocyte/macrophage cytokines/chemokines/adipokines CCL2, CCL4, IL-1β, TNF-α, IL-6, PTX3, leptin, adiponectin, PAI-1, OPG and ICAM-1 and compared these levels to healthy controls (HC) (n=138). Using multivariate analysis, we studied the effect of the presence of the disease SZ, the components of the metS including BMI, the levels of lipids (HDL cholesterol and triglycerides (TG)), diabetes (hyperglycemia) and the use of antipsychotic medication, on the serum levels of these immune compounds. We found all measured immune compounds with the exception of PAI-1 and OPG to be elevated in the SZ patient population. Multivariate analysis showed that elevations were linked to gender (ICAM-1, leptin, TNF-α and adiponectin), an increased BMI (leptin, adiponectin), hyperglycemia/diabetes (CCL4, and OPG), reduced HDL-cholesterol or increased levels of TG (adiponectin and PTX3) or the metS (CCL2, leptin and adiponectin). IL-1β and IL-6 were the only immune compounds raised in the serum of patients not affected by any of the included factors. Although many of the immune compounds were found linked to (components of) the metS, the most dominant linkage was found with the disease schizophrenia, confirming earlier reports on increased monocyte/macrophage activation as a key component for understanding the pathogenesis of schizophrenia.

Cytogenetic analysis of malignant mesothelioma

Cytogenetic analyses of 40 confirmed malignant mesotheliomas (MMs) are reported. Pleural effusion cells were studied in 90% of the cases by direct method or after culture or both. Biopsy and ascites fluid were also analyzed in some patients. A normal karyotype was found in nine cases, and complex karyotypic abnormalities were observed in 30 cases. In one case, analyzable metaphases were not obtained. The chromosomal changes were all complex and heterogeneous; no consistent presumably specific abnormality was detected. Nevertheless, two main patterns of nonrandom abnormalities were observed: 1) loss of chromosomes 4 and 22, 9p, and 3p in the most of the abnormal cases and corresponding to a hypodiploid and/or hypotetraploid modal chromosome number; and 2) gain of chromosomes 7, 5, and 20 with deletion or rearrangement of 3p as well in the hyperdiploid cases, which were a minority in our series. These findings are discussed in view of other reported cytogenetic studies of MM, asbestos exposure, and possible mechanisms of malignant transformation.

The activation of monocyte and T cell networks in patients with bipolar disorder.

OBJECTIVES We recently described a monocyte pro-inflammatory state in patients with bipolar disorder (BD). We hypothesized that the CD4(+)T cell system is also activated and determined percentages of Th1, Th2, Th17 and CD4(+)CD25(high)FoxP3(+) regulatory T cells. METHODS We carried out a detailed FACS analysis to determine the various T cell subsets and used frozen stored peripheral blood mononuclear cells (PBMC) of 38 BD patients (of whom we previously had tested monocytes for pro-inflammatory gene expression (Drexhage et al., 2010b; Padmos et al., 2008)) and of 22 age/gender matched healthy controls (HC). In addition the cytokines CCL2, IL-1β, IL-6, TNF-α, PTX3, IL-10, IFN-γ, IL-17A, IL-4, IL-5 and IL-22 were measured in serum. RESULTS (a) Serum sCD25 levels and percentages of anti-inflammatory CD4(+)CD25(high)FoxP3+ regulatory T cells were higher, the latter in BD patients <40 years of age. Percentages of Th1, Th2 and Th17 cells were normal. (b) Of the pro-inflammatory monocyte cytokines CCL2 and PTX3 were raised in serum. (c) The monocyte pro-inflammatory state and the raised percentages of CD4(+)CD25(high)FoxP3(+) regulatory T cells occurred independently from each other. (d) In BD patients positive for thyroid autoimmune disease a significantly reduced percentage of CD4(+)CD25(high)FoxP3(+) regulatory T cells was found as compared to BD patients without AITD. CONCLUSION Our data show an enhancement of pro-inflammatory monocyte and anti-inflammatory T cell forces in BD patients. A lack of anti-inflammatory T cell forces co-occurred with AITD in BD patients.

EXPRESSION OF PLATELET-DERIVED GROWTH FACTOR (PDGF) AND PDGF RECEPTORS IN HUMAN MALIGNANT MESOTHELIOMA IN VITRO AND IN VIVO

The expression of platelet‐derived growth factor (PDGF) and PDGF receptors was studied in human normal and malignant mesothelial cells in vitro and in vivo. Staining with anti‐cytokeratin and ME1 antibodies and ultrastructural analysis confirmed the mesothelial nature of the cell lines used to study PDGF and PDGF receptor expression in vitro. Using antibodies, mesothelioma cell lines were found to express PDGF and both the PDGF α‐ and the PDGF β‐receptor, whereas cultured normal mesothelial cells expressed PDGF and PDGF α‐receptor. This PDGF and PDGF receptor staining pattern largely reflects the earlier described mRNA expression in these cell lines. The only exception was the immunocytochemical detection of PDGF α‐receptors in the mesothelioma cell lines, which is different from the inability to detect α‐receptor transcripts on Northern blots. Expression was also investigated in mesothelial cells in vivo. Expression of PDGF was observed in malignant mesothelioma cells on frozen tissue sections. In pleural effusions, a double immunofluorescence staining procedure for PDGF and epithelial membrane antigen (EMA) revealed PDGF expression by EMA‐positive malignant mesothelioma cells. PDGF β‐receptors and occasionally PDGF α‐receptors were detected in frozen tissue sections of malignant mesotheliomas, whereas mesothelioma cells in effusions showed faint expression of only the PDGF β‐receptor. In contrast, in effusions containing non‐malignant mesothelial cells, only a very low level of PDGF α‐receptor could be detected. Taken together, these results indicate that the pattern of PDGF and PDGF receptor expression in mesothelial cells in vivo largely corresponds to expression of PDGF and its receptors in vitro. Malignant mesothelioma cell lines thus constitute a good model system for studies on the role of PDGF in this malignancy. Furthermore, the data reported in this paper are consistent with the idea that an autocrine growth stimulatory effect of PDGF via PDGF receptors may play a role in the pathogenesis of malignant mesothelioma.

The gene for the cyclin-dependent-kinase-4 inhibitor, CDKN2A, is preferentially deleted in malignant mesothelioma

Cytogenetic deletions of the short arm of chromosome 9, 9p, have been detected in cell lines of malignant mesothelioma as well as in tumor material. Many tumor types carry deletions of chromosome 9 or more specifically of 9p21. The tumor‐suppressor genes, CDKN2A and CDKN2B, each of which encodes a structurally and functionally similar cyclin‐dependent kinase inhibitor, were mapped to the commonly deleted region. The tumor‐suppressive effect of these genes, or of CDKN2A alone, requires functional retinoblastoma protein, pRb. Malignant mesothelioma expresses pRb, which, together with the cytogenetic data, suggests the involvement of CDKN2A and/or CDKN2B in its tumorigenesis. We present data on the deletion status of chromosome 9 in malignant mesothelioma cell lines and tumor tissue. A deletion map of the 9p21.3‐p23 region was constructed for 12 cell lines. Homozygous deletions of chromosomal regions containing CDKN2A were detected in all cell lines. The smallest region of overlap for deletion is approximately 24 kb, and does not include CDKN2B. The frequency of deletion of the centromeric region of chromosome 9 was compared with that of chromosomes 1, 6, and 10 by genomic in situ hybridization. Deletion of the centromere of chromosome 9 is the predominant event at a frequency of 73 ± 3%. Our data show that deletions of a critical region of chromosome 9, including the CDKN2A but not the CDKN2B locus, are common among malignant mesothelioma. Such deletions may be involved in tumorigenesis of mesothelium. Int. J. Cancer 75:649–653, 1998.