Biomedical subjects

Elise S van Haastert

Publications and source records attributed to Elise S van Haastert.

7 recordsLinked to original sources

PubMed2007

Microglia activation in sepsis: a case-control study.

BACKGROUND: Infection induces an acute phase response that is accompanied by non-specific symptoms collectively named sickness behavior. Recent observations suggest that microglial cells play a role in mediating behavioral changes in systemic infections. In animal models for sepsis it has been shown that after inducing lipopolysaccharide, LPS, microglia in the brain were activated. The aim of this study was to investigate whether activation of microglia can be detected in patients who died of sepsis. METHODS: In a case-control study brain tissue of 13 patients who died with sepsis was compared with that of 17 controls. Activated microglia were identified by expression of MHC-class II antigens and CD68. Microglia activation was analyzed by a semiquantitative score combining both the number of the immunoreactive cells and their morphology. RESULTS: In patients who died with sepsis there was a significant increase in activated microglia in the grey matter when stained with CD68 compared to controls. This effect was independent of the effect of age. CONCLUSION: This study shows for the first time in human brain tissue an association between a systemic infection and activation of microglia in the brain. Activated microglia during sepsis could play a role in behavioral changes associated with systemic infection.

Adult↗

PubMed2006

The unfolded protein response affects neuronal cell cycle protein expression: implications for Alzheimer's disease pathogenesis.

Alzheimer's disease (AD) is characterized by the accumulation and aggregation of misfolded proteins. The presence of misfolded proteins in the endoplasmic reticulum (ER) triggers a cellular stress response called the unfolded protein response (UPR). Previously, we have shown that the UPR is activated in AD neurons. In actively dividing cells, activation of the UPR is accompanied by decreased cell cycle protein expression and an arrest in the G1 phase of the cell cycle. Aberrant expression of cell cycle proteins has been observed in post mitotic neurons in AD and is suggested to be involved in neurodegeneration. In this study we show that the protein levels of BiP/GRP78, an ER-stress marker, is increased in Braak stages B and C for amyloid deposits. This is in contrast to the levels of cell cycle markers cyclin D1, cyclin E and phosphorylated retinoblastoma protein (ppRb) which are decreased in Braak stage C compared to Braak stage A for amyloid deposits. In addition, we report a negative correlation between neuronal expression of ppRb and expression levels of BiP/GRP78 in control and AD cases. Activation of the UPR in neuronal cells induces changes in cell cycle protein expression similar to these observed in AD brain. ER stress inducers tunicamycin and thapsigargin down-regulate cell cycle proteins ppRb and cyclin D1 in differentiated neuroblastoma cells. In contrast, protein levels of p27, a cyclin dependent kinase inhibitor, are increased after induction of ER-stress using tunicamycin. These data suggest that activation of the UPR affects cell cycle protein expression in neurons during neurodegeneration in AD.

Alzheimer Disease↗

PubMed2006

Simvastatin affects cell motility and actin cytoskeleton distribution of microglia.

Statin treatment is proposed to be a new potential therapy for multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system. The effects of statin treatment on brain cells, however, are hardly understood. We therefore evaluated the effects of simvastatin treatment on the migratory capacity of brain microglial cells, key elements in the pathogenesis of MS. It is shown that exposure of human and murine microglial cells to simvastatin reduced cell surface expression of the chemokine receptors CCR5 and CXCR3. In addition, simvastatin treatment specifically abolished chemokine-induced microglial cell motility, altered actin cytoskeleton distribution, and led to changes in intracellular vesicles. These data clearly show that simvastatin inhibits several immunological properties of microglia, which may provide a rationale for statin treatment in MS.

Actins↗

PubMed2005

Maximal COX-2 and ppRb expression in neurons occurs during early Braak stages prior to the maximal activation of astrocytes and microglia in Alzheimer's disease.

Neuronal expression of cyclooxygenase-2 (COX-2) and cell cycle proteins is suggested to contribute to neurodegeneration during Alzheimer's disease (AD). The stimulus that induces COX-2 and cell cycle protein expression in AD is still elusive. Activated glia cells are shown to secrete substances that can induce expression of COX-2 and cell cycle proteins in vitro. Using post mortem brain tissue we have investigated whether activation of microglia and astrocytes in AD brain can be correlated with the expression of COX-2 and phosphorylated retinoblastoma protein (ppRb). The highest levels of neuronal COX-2 and ppRb immunoreactivity are observed in the first stages of AD pathology (Braak 0-II, Braak A). No significant difference in COX-2 or ppRb neuronal immunoreactivity is observed between Braak stage 0 and later Braak stages for neurofibrillary changes or amyloid plaques. The mean number of COX-2 or ppRb immunoreactive neurons is significantly decreased in Braak stage C compared to Braak stage A for amyloid deposits. Immunoreactivity for glial markers KP1, CR3/43 and GFAP appears in the later Braak stages and is significantly increased in Braak stage V-VI compared to Braak stage 0 for neurofibrillary changes. In addition, a significant negative correlation is observed between the presence of KP1, CR3/43 and GFAP immunoreactivity and the presence of neuronal immunoreactivity for COX-2 and ppRb. These data show that maximal COX-2 and ppRb immunoreactivity in neurons occurs during early Braak stages prior to the maximal activation of astrocytes and microglia. In contrast to in vitro studies, post mortem data do not support a causal relation between the activation of microglia and astrocytes and the expression of neuronal COX-2 and ppRb in the pathological cascade of AD.

Journal Article↗

PubMed2005

Blood-brain barrier alterations in both focal and diffuse abnormalities on postmortem MRI in multiple sclerosis.

Postmortem MRI-guided tissue sampling significantly enhances the yield of MS lesions in autopsy material, but so far it is unknown whether abnormalities concur with blood-brain barrier alterations. Here we sampled MS lesions with focal and diffuse abnormalities (diffusely abnormal white matter; DAWM) on MRI; both were coupled to the presence of MS lesions upon neuropathological examination. Extravascular distribution of fibrinogen, indicating BBB disturbance, was observed in so-called (p)reactive lesions that reflect discrete areas of microglial activation without demyelination within an otherwise normal appearing white matter. Leakage became more extensive in active demyelinating MS lesions to chronic inactive lesions. An enlargement of the perivascular (Virchow-Robin) space containing infiltrated leukocytes was associated with both DAWM and focal abnormalities on postmortem MRI. This study shows for the first time that in MS brain changes in the vasculature take place not only in focal lesions but also in DAWM as detected by postmortem MRI.

Aged↗

PubMed2003

Matrix metalloproteinase-12 is expressed in phagocytotic macrophages in active multiple sclerosis lesions.

Matrix metalloproteinases (MMPs) are proteases involved in extracellular matrix (ECM) remodeling, leukocyte infiltration into lesions and myelin degradation in the central nervous system (CNS) disease multiple sclerosis (MS). We have investigated whether MMP-12 (macrophage metalloelastase) is expressed in MS lesions at various stages. In control patient tissue and (p)reactive MS lesions, only occasional microglial and astrocyte staining was detected. In contrast, in active demyelinating lesions, phagocytic macrophages were MMP-12 positive. A lower proportion of phagocytes was positive for MMP-12 in chronic active demyelinating lesions and inactive lesions. This suggests a role for MMP-12 during demyelination in MS.

Adult↗

PubMed2003

CX3CL1 and CX3CR1 expression in human brain tissue: noninflammatory control versus multiple sclerosis.

An important role for CX3CL1 in neuroinflammation and neurodegeneration has been suggested in recent publications. In this study, we compared the expression of CX3CL1 and its receptor CX3CR1 in human brain tissue derived from control patients without neurological complications and in multiple sclerosis (MS) patients. Results from this study demonstrate that CX3CL1 is constitutively expressed in human central nervous system (CNS) astrocytes in vivo and under basal conditions in human adult astrocyte cultures. CX3CR1 is expressed on astrocytes and microglial cells both in vivo and in vitro. Chemotaxis assay shows a functional response upon CX3CR1 signaling in microglial cells. Although CX3CL1 expression is upregulated in cultured astrocytes in response to proinflammatory cytokines, no evidence for expression differences of CX3CL1 between control patients and MS patients was found. Our data suggest that CX3CL1 has more general physiological functions, which occur also in the absence of proinflammatory conditions.

Adult↗