den Wilfred Dunnen

The role of CXC chemokine ligand (CXCL)12-CXC chemokine receptor (CXCR)4 signalling in the migration of neural stem cells towards a brain tumour

Aims: It has been shown that neural stem cells (NSCs) migrate towards areas of brain injury or brain tumours and that NSCs have the capacity to track infiltrating tumour cells. The possible mechanism behind the migratory behaviour of NSCs is not yet completely understood. As chemokines are involved in the migration of immune cells in the injured brain, they may also be involved in chemoattraction of NSCs towards a brain tumour. Methods: The expression profile of various chemokine receptors in NSCs, harvested from the subventricular zone of adult mice, was investigated by reverse transcriptase‐ polymerase chain reaction analysis. Furthermore, the functionality of the chemokine receptors was assessed in in vitro chemotaxis assays and calcium signalling experiments. To test the in vivo migration of NSCs, a syngeneic mouse model was developed, whereby a B16F10 melanoma cell line was grafted into one hemisphere and later NSCs were grafted in the contralateral hemisphere. Furthermore, the expression of chemokines in this melanoma cell line was investigated. Results and conclusions: Adult mouse NSCs functionally express various chemokine receptors of which CXC chemokine receptor (CXCR)4 shows the highest mRNA levels and most pronounced functional responses in vitro. CXC chemokine ligand (CXCL)12, the ligand for CXCR4, is expressed by the melanoma cell line. In this mouse model for metastatic brain tumours, it is shown that NSCs express CXCR4 at their cell membranes while they migrate towards the tumour, which produces CXCL12. It is therefore suggested that the CXCR4/CXCL12 pathway plays a role in the mechanism underlying tumour‐mediated attraction of NSCs.

The p62 antibody reveals various cytoplasmic protein aggregates in spinocerebellar ataxia Type 6

Neuronal protein aggregates are considered as pathological hallmarks of various human neurodegenerative diseases, including the so-called CAG-repeat disorders, such as spinocerebellar ataxia Type 6 (SCA6). Since the immunocytochemical findings of an initial post-mortem study using a specific antibody against the disease protein of SCA6 (i.e., pathologically altered alpha-1A subunit of the P/Q type voltage-dependent calcium channel, CACNA1A) have not been confirmed so far, the occurrence and central nervous system distribution of neuronal protein aggregates in SCA6 is still a matter of debate. Owing to the fact that the antibody against the pathologically altered CACNA1A is not commercially available, we decided to apply a recently generated p62 antibody on brain tissue from two clinically diagnosed and genetically confirmed SCA6 patients. Application of this p62 antibody revealed numerous cytoplasmic neuronal inclusions in the degenerated cerebellar dentate nucleus and inferior olive of both SCA6 patients studied, whereby a subset of these aggregates were also ubiquitin-immunopositive. In view of the known role of p62 in protein degradation as well as aggresome/sequestosome formation, the p62 aggregate formation observed in the present study suggests that SCA6 not only is associated with an impairment of the calcium channel function and an elongated polyglutamine stretch in CACNA1A, but also with a defective protein handling by the protein quality control system.

The chemokine network, a newly discovered target in high grade gliomas

Chemokines are small cytokines, characterised by their ability to induce directional migration of cells by binding to chemokine receptors. They are known to play a role in tumour development, angiogenesis and metastasis. Interestingly, the chemokine network also contributes to the progression of gliomas, mainly by intensifying their characteristic invasive character. The main hurdle in treatment of these tumours is their infiltration of surrounding tissues, hampering complete surgical tumour removal. Standard postsurgical treatment with radio- and chemotherapy is of limited effect. Therefore drugs that target the chemokine system in high grade gliomas might fill the gap existing in the current approach. This review presents the current knowledge of the role of chemokine network in the development of the central nervous system, in brain physiology and the involvement in brain tumour progression. Finally, current studies exploring new compounds targeting the chemokine network in cancer patient are discussed.

Vascular endothelial growth factor receptor 2 (VEGFR‐2) signalling activity in paediatric pilocytic astrocytoma is restricted to tumour endothelial cells

A. H. Sikkema, E. S. J. M. de Bont, G. Molema, A. Dimberg, P. J. Zwiers, S. H. Diks, E. W. Hoving, W. A. Kamps, M. P. Peppelenbosch and W. F. A. den Dunnen (2011) Neuropathology and Applied Neurobiology37, 538–548

Spinal hemorrhages are associated with early neonatal motor function loss in human spina bifida aperta

BACKGROUND In spina bifida aperta (SBA), leg movements caudal to the meningomyelocele are present in utero, but they disappear shortly after birth. It is unclear whether leg movements disappear by impact of the neuro-developmental malformation or by superimposed traumatic damage. If superimposed traumatic damage is involved, targeted fetal intervention could improve motor outcome. AIM To characterize neuromuscular pathology in association with perinatal motor function loss in SBA. PATIENTS/METHODS In fetal SBA (n=8; 16-40 weeks GA), the median time interval between ultrasound registrations of fetal motor behavior and post-mortem histology was 1 week. Histology was assessed cranial, at and caudal to the meningomyelocele and compared with findings in fetal controls (n=4). RESULTS Despite fetal movements caudal to the meningomyelocele (5/6), histology indicated muscle fiber alterations (6/6) that concurred with neuro-developmental and traumatic spinal defects [Neuro-developmental defects: spinal ependymal denudation (3/8), reduced amount of (caspase3-negative) lower motor neurons (LMNs; 8/8), aberrant spinal vascularization (8/8). Traumatic defects: gliosis (7/8), acute/fresh spinal hemorrhages near LMNs (8/8)]. CONCLUSION In all delivered SBA patients, recent spinal hemorrhages were superimposed upon pre-existing defects. If early therapeutic strategies can prevent these superimposed secondary spinal hemorrhages, motor outcome may improve.

Inhibition of formyl peptide receptor in high-grade astrocytoma by CHemotaxis Inhibitory Protein of S. aureus

Background:High-grade astrocytomas are malignant brain tumours that infiltrate the surrounding brain tissue and have a poor prognosis. Activation of formyl peptide receptor (FPR1) on the human astrocytoma cell line U87 promotes cell motility, growth and angiogenesis. We therefore investigated the FPR1 inhibitor, Chemotaxis Inhibitory Protein of S. aureus (CHIPS), as a potential anti-astrocytoma drug.Methods and results:FPR1 expression was studied immunohistochemically in astrocytomas WHO grades I–IV. With intracellular calcium mobilisation and migration assays, human ligands were tested for their ability to activate FPR1 on U87 cells and on a cell line derived from primary astrocytoma grade IV patient material. Thereafter, we selectively inhibited these ligand-induced responses of FPR1 with an anti-inflammatory compound called Chemotaxis Inhibitory Protein of S. aureus (CHIPS). U87 xenografts in NOD-SCID mice served to investigate the effects of CHIPS in vivo. FPR1 was expressed in 29 out of 32 (90%) of all grades of astrocytomas. Two human mitochondrial-derived formylated peptides, formyl-methionil-leucine-lysine-isoleucine-valine (fMLKLIV) and formyl-methionil-methionil-tyrosine-alanine-leucine-phenylalanine (fMMYALF), were potent activators of FPR1 on tumour cells. Ligand-induced responses of FPR1-expressing tumour cells could be inhibited with FPR1 inhibitor CHIPS. Treatment of tumour-bearing mice with CHIPS slightly reduced tumour growth and improved survival as compared to non-treated animals (P=0.0019).Conclusion:Targeting FPR1 with CHIPS reduces cell motility and tumour cell activation, and prolongs the survival of tumour-bearing mice. This strategy could be explored in future research to improve treatment results for astrocytoma patients.

Muscle ultrasound density in human fetuses with spina bifida aperta

BACKGROUND In fetal spina bifida aperta (SBA), leg movements caudal to the meningomyelocele (MMC) are transiently present, but they disappear shortly after birth. Insight in the underlying mechanism could help to improve treatment strategies. In fetal SBA, the pathogenesis of neuromuscular damage prior to movement loss is still unknown. We reasoned that prenatal assessment of muscle ultrasound density (fetal-MUD) could help to reveal whether progressive neuromuscular damage is present in fetal SBA, or not. AIM To reveal whether prenatal neuromuscular damage is progressively present in SBA. PATIENTS/METHODS In SBA fetuses (n=6; 22-37 weeks gestational age), we assessed fetal-MUD in myotomes caudal to the MMC and compared measurements between myotomes cranial to the MMC and controls (n=11; 17-36 weeks gestational age). Furthermore, we intra-individually compared MUD and muscle histology between the pre- and postnatal period. RESULTS Despite persistently present fetal leg movements caudal to the MMC, fetal-MUD was higher caudal to the MMC than in controls (p<0.05). Fetal-MUD caudal to the MMC did not increase with gestational age, whereas fetal-MUD in controls and cranial to the MMC increased with gestational age (p<0.05). In 5 of 6 patients assessed, comparison between pre- and postnatal MUD and/or muscle histology indicated consistent findings. CONCLUSIONS In fetal SBA, persistent leg movements concur with stable, non-progressively increased fetal-MUD. These data may implicate that early postnatal loss of leg movements is associated with the impact of additional neuromuscular damage after the prenatal period.

Involvement of the cholinergic basal forebrain nuclei in spinocerebellar ataxia type 2 (SCA2)

Spinocerebellar ataxia type 2 (SCA2) belongs to the CAG repeat or polyglutamine diseases. Along with a large variety of motor, behavioural and neuropsychological symptoms the clinical picture of patients suffering from this autosomal dominantly inherited ataxia may also include deficits of attention, impairments of memory, as well as frontal‐executive and visuospatial dysfunctions. As the possible morphological correlates of these cognitive SCA2 deficits are unclear we examined the cholinergic basal forebrain nuclei, which are believed to be crucial for several aspects of normal cognition and may contribute to impairments of cognitive functions under pathological conditions.

Widespread thalamic and cerebellar degeneration in a patient with a complicated hereditary spastic paraplegia (HSP)

The hereditary spastic paraplegias (HSP) are a heterogeneous group of familial movement disorders sharing progressive spastic paraplegia as a common disease sign. In the present study, we performed the first pathoanatomical investigation of the central nervous degeneration of a female patient with a complicated HSP form who suffered from progressive spastic paraplegia, dysarthria, emotional symptoms, cognitive decline and a variety of additional neuropsychological deficits. This pathoanatomical investigation revealed in addition to loss of layer V Betz pyramidal cells in the primary motor cortex, widespread cerebellar neurodegeneration (i.e., loss of Purkinje cells and neuronal loss in the deep cerebellar nuclei), extensive and severe neuronal loss in a large number of thalamic nuclei, involvement of some brainstem nuclei, as well as damage to descending (i.e., lateral and ventral corticospinal tracts) and ascending (i.e., dorsal and ventral spinocerebellar tracts, gracile fascicle) fiber tracts. In view of their known functional role, damage to these central nervous gray and white matter components offers explanations for the patients pyramidal signs, her cerebellar, psychiatric and neuropsychological disease symptoms.

Polyglutamine aggregation in Huntington's disease and spinocerebellar ataxia type 3

Polyglutamine (polyQ) diseases are characterized by the expansion of a polymorphic glutamine sequence in disease‐specific proteins and exhibit aggregation of these proteins. This is combated by the cellular protein quality control (PQC) system, consisting of chaperone‐mediated refolding as well as proteasomal and lysosomal degradation pathways. Our recent study in the polyQ disease spinocerebellar ataxia type 3 (SCA3) suggested a distinct pattern of protein aggregation and PQC dysregulation.