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Corline J A De Groot

Publications and source records attributed to Corline J A De Groot.

7 recordsLinked to original sources
PubMed2005

CD163-positive perivascular macrophages in the human CNS express molecules for antigen recognition and presentation.

Perivascular macrophages (PVM) constitute a subpopulation of resident macrophages in the central nervous system (CNS) that by virtue of their strategic location at the blood-brain barrier potentially lend themselves to a variety of important functions in both health and disease. Functional evidence suggests that PVM play a supportive role during experimental autoimmune encephalomyelitis in rodents. However, the function of PVM in the human CNS remains poorly characterized. We first set out to investigate the validity of the antibody EDhu1, which recognizes human CD163, to specifically identify human PVM. Second, we wanted to gain insight into the function of PVM in antigen recognition and presentation and therefore we studied the expression of DC-SIGN, mannose receptor, MHC class II, and several costimulatory molecules by PVM in the normal and inflamed human CNS (multiple sclerosis (MS) brain lesions). Conventional immunohistochemistry and double-labeled immunofluorescence techniques were used. We show that CD163 specifically reveals PVM in the normal human CNS. In MS lesions, CD163 staining reveals expression on foamy macrophages and microglia, besides an upregulation of the amount of PVM stained. In contrast, mannose receptor expression is restricted to PVM in both normal and inflamed brain tissue. Furthermore, we show that a subpopulation of PVM in the human brain express several molecules involved in antigen recognition, presentation, and costimulation. Therefore PVM, which occupy a strategic location at the BBB, are equipped to recognize antigen and present it to T cells, supporting a role in the regulation of perivascular inflammation in the human CNS.

Aged↗
PubMed2004

Multiple sclerosis as a generalized CNS disease--comparative microarray analysis of normal appearing white matter and lesions in secondary progressive MS.

We used microarrays to compare the gene expression profile in active lesions and donor-matched normal appearing white matter (NAWM) from brain autopsy samples of patients with secondary progressive multiple sclerosis (MS) with that from controls who died from non-neurological diseases. The 123 genes in lesions, and 47 genes in NAWM(MS) were differentially expressed. Lesions distinguished from NAWM(MS) by a higher expression of genes related to immunoglobulin synthesis and neuroglial differentiation, while cellular immune response elements were equally dysregulated in both tissue compartments. Current results provide molecular evidence of a continuum of dysfunctional homeostasis and inflammatory changes between lesions and NAWM(MS), and support the concept of MS pathogenesis being a generalised process that involves the entire CNS.

Brain↗
PubMed2003

Remyelinated lesions in multiple sclerosis: magnetic resonance image appearance.

BACKGROUND: Various types of pathologic mechanisms in multiple sclerosis (MS) can alter magnetic resonance imaging (MRI) signals, and the appearance of remyelinated lesions on MRI is largely unknown. OBJECTIVE: To describe the MRI appearance of remyelinated lesions in MS. DESIGN: Comparison of postmortem MRI findings with histopathologic findings. SETTING: Brain donations from a general community. Patients Magnetic resonance images from 36 rapid autopsies yielded 161 areas that could be matched with histologic characteristics, including 149 focal T2-weighted abnormalities, with a range of signal intensities on T1-weighted images. In a subset of 49 lesions, magnetization transfer ratio could be determined. MAIN OUTCOME MEASURES: An observer blinded to the MRI findings assessed the presence of remyelination using light microscopic criteria; in 25 areas, in situ hybridization was used to assess the presence of oligodendrocytes expressing proteolipid protein messenger RNA. RESULTS: Remyelinated areas were found in 67 lesions (42%): partial remyelination was present in 30 lesions (19%), whereas 37 lesions (23%) were fully remyelinated. Remyelinated lesions contained enhanced numbers of oligodendrocytes containing proteolipid protein messenger RNA. All areas with remyelination shown histopathologically were hyperintense on T2-weighted images. Strong hypointensity on T1-weighted images was significantly associated (chi2 = 29.8, P<.001) with demyelinated and partially remyelinated lesions compared with fully remyelinated lesions. The magnetization transfer ratio of remyelinated lesions (mean [SD], 27.6% [41%]) differed (F = 46.3, P<.001) from both normal-appearing white matter (35.2% [32%]) and demyelinated lesions (22.3% [48%]). CONCLUSIONS: Remyelinated lesions return an abnormal signal on T2-weighted images. Both T1-weighted images and magnetization transfer ratio may have (limited) additional value in separating lesions with and without remyelination.

Adult↗
PubMed2003

Role of IDO activation in anti-microbial defense in human native astrocytes.

The most serious complication of human toxoplasmosis is the development of toxoplasmic encephalitis. It is well established that in the brain Toxoplasma gondii is able to replicate in microglial cells, astrocytes and neurons, and that all three cell types can harbor toxoplasma cysts. The role of astrocytes in the defense against toxoplasma is not clear. The most prominent effector-mechanisms against toxoplasma are the induction of the inducible form of the nitric oxide synthase (iNOS), and the induction of indoleamine 2,3-dioxygenase (IDO). In this paper we show that interferon (IFN)-gamma-activated, native human astrocytes express IDO activity, as shown by the detection of IDO mRNA using RT-PCR, detection of enzyme expression with IDO-specific monoclonal antibodies in Western blots, as well as by direct measurement of enzyme activity in the activated cells. IFN-gamma-mediated IDO activity in human astrocytes inhibits the growth of Toxoplasma gondii and of group B streptococci. Furthermore, we show for the first time that IFN-gamma induced IDO activity is also effective in inhibiting the growth of Herpes Simplex Virus in astrocyte cultures. In addition, iNOS expression was detectable by RT-PCR in all batches of astrocytes tested when stimulated with a cytokine cocktail of IFN-gamma, TNF-alpha, IL-1 and LPS. Furthermore, we found that the amount of nitric oxide produced by astrocytes is not sufficient to inhibit either toxoplasmal or bacterial growth. Co-activation of iNOS and IDO on the other hand, results in an inhibition of IDO activity in astrocytes.

Animals↗
PubMed2002

Cellular localization and expression patterns of interleukin-10, interleukin-4, and their receptors in multiple sclerosis lesions.

Cytokines have been shown to play a crucial role in the pathogenesis of multiple sclerosis (MS). However, still limited data are available on the expression of anti-inflammatory cytokines within the central nervous system (CNS) during MS lesion development. Therefore, we have examined the expression of the anti-inflammatory cytokines, interleukin-10 (IL-10) and IL-4, and their specific receptors, IL-10R and IL-4R, in postmortem human brain tissue obtained from MS patients. Specific patterns of protein localization and expression for both proteins could be observed within active and chronic MS lesions. Strongest IL-10 immunoreactivity was observed in reactive astrocytes within active demyelinating lesions and the hypercellular rim of chronic active MS lesions. Moreover, perivascular macrophages were immunoreactive for IL-10 in (chronic) active MS lesions. Most intense IL-4 immunoreactivity was detected in reactive fibrillary astrocytes within the hypocellular regions of chronic active and chronic inactive MS lesions. Strong immunoreactivity for IL-10R and IL-4R was detected on macrophages in both parenchymal and perivascular areas and on reactive astrocytes in active and chronic MS lesions. Our results indicate that IL-10 and IL-4 have an active role in CNS immune responses. The specific patterns of protein localization and protein expression for both IL-10 and IL-4 in MS lesions at different stages of development suggest that these anti-inflammatory cytokines and their receptors participate in processes leading to the formation of chronic MS lesions.

Adult↗
PubMed2002

Beneficial effect of modified peptide inhibitor of alpha4 integrins on experimental allergic encephalomyelitis in Lewis rats.

An important event in the pathogenesis of the autoimmune disease multiple sclerosis (MS) is the recruitment of lymphocytes and inflammatory macrophages to the central nervous system (CNS). Recruitment requires adhesive interactions between the leukocytes and the microvascular endothelium, perivascular cells, and astrocytes in the CNS parenchyma. Previous studies using an animal model of MS, experimental allergic encephalomyelitis (EAE), have shown the involvement of the alpha4 integrin VLA-4 (beta4beta1). In the present study, the effect of a modified peptide inhibitor of alpha4 integrins on the clinical course and leukocyte infiltration during EAE is investigated. EAE was either induced actively, by immunizing Lewis rats with whole guinea pig MBP, or passively, by transfer of an MBP-specific T cell line. Treatment with the inhibitor (CS1 ligand mimic) completely prevented both clinical signs and cellular infiltration in passively induced EAE. Peptide treatment of actively induced EAE, which has a more severe disease course than the transfer model, significantly reduced clinical signs although the recruitment of inflammatory cells and induction of MHC class II expression was not prevented. The alpha4 inhibitor did inhibit the adhesion of lymphocytes to primary astrocytes in vitro suggesting a role for astrocyte-leukocyte interactions in the pathogenesis of induced EAE. Astrocytes were found to express an extracellular matrix protein distinct from fibronectin, which shows immune cross-reactivity with the CS1 domain of fibronectin. Our results show that small-molecule inhibitors of alpha4 integrins act therapeutically in EAE possibly by interfering with cell adhesion events involved in this autoimmune disease.

Animals↗