1.
Björkqvist, Maria, et al.
(author)
A novel pathogenic pathway of immune activation detectable before clinical onset in Huntington's disease.
2008
In: Journal of Experimental Medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 205, s. 1869-1877
Journal article (peer-reviewed) abstract
Huntington's disease (HD) is an inherited neurodegenerative disorder characterized by both neurological and systemic abnormalities. We examined the peripheral immune system and found widespread evidence of innate immune activation detectable in plasma throughout the course of HD. Interleukin 6 levels were increased in HD gene carriers with a mean of 16 years before the predicted onset of clinical symptoms. To our knowledge, this is the earliest plasma abnormality identified in HD. Monocytes from HD subjects expressed mutant huntingtin and were pathologically hyperactive in response to stimulation, suggesting that the mutant protein triggers a cell-autonomous immune activation. A similar pattern was seen in macrophages and microglia from HD mouse models, and the cerebrospinal fluid and striatum of HD patients exhibited abnormal immune activation, suggesting that immune dysfunction plays a role in brain pathology. Collectively, our data suggest parallel central nervous system and peripheral pathogenic pathways of immune activation in HD.
2.
Grey, Marie, et al.
(author)
Acceleration of α-synuclein aggregation by exosomes
2015
In: Journal of Biological Chemistry. - 1083-351X. ; 290:5, s. 2969-2982
Journal article (peer-reviewed) abstract
Exosomes are small vesicles released from cells into extra-cellular space. We have isolated exosomes from neuroblastoma cells and investigated their influence on the aggregation of α-synuclein, a protein associated with Parkinson disease pathology. Using cryo-transmission electron microscopy of exosomes we found spherical unilamellar vesicles with a significant protein content, and Western blot analysis revealed that they contain, as expected, the proteins flotillin-1 and alix. Using thioflavin T fluorescence to monitor aggregation kinetics, we found that exosomes catalyze the process in a similar manner as low concentration of preformed α-synuclein fibrils. The exosomes reduce the lag time indicating that they provide catalytic environments for nucleation. The catalytic effect of exosomes derived from naive cells and cells that over-express α-synuclein do not differ. Vesicles prepared from extracted exosome lipids accelerate aggregation, suggesting that the lipids in exosomes are sufficient for the catalytic effect to arise. Using mass spectrometry we found several phospholipid classes in the exosomes, including phosphatidyl choline, phosphatidyl serine, phosphatidyl ethanolamine, phosphatidyl inositol and the gangliosides GM2 and GM3. Within each class, several species with different acyl chains were identified. We then prepared vesicles from corresponding pure lipids or defined mixtures, most of which were found to retard α-synuclein aggregation. As a striking exception, vesicles containing ganglioside lipids GM1 or GM3 accelerate the process. Understanding how α-synuclein interacts with biological membranes to promote neurological disease might lead to the identification of novel therapeutic targets.
3.
Hansson, Oskar, et al.
(author)
Partial resistance to malonate-induced striatal cell death in transgenic mouse models of Huntington's disease is dependent on age and CAG repeat length
2001
In: Journal of Neurochemistry. - Lund Univ, Sect Neuronal Survival, Wallenberg Neurosci Ctr, Dept Physiol Sci, S-22184 Lund, Sweden. State Univ Campinas, Sch Med Sci, Dept Clin Pathol, Campinas, SP, Brazil. Univ Uppsala, Dept Neurosci, Uppsala, Sweden. GKT, Sch Med, London, England. : BLACKWELL SCIENCE LTD. - 0022-3042 .- 1471-4159. ; 78:4, s. 694-703
Journal article (peer-reviewed) abstract
Transgenic, Huntington's disease (HD) mice, expressing exon I of the HD gene with an expanded CAG repeat, are totally resistant to striatal, lesion induced by excessive NMDA receptor activation. We now show that striatal lesions induced by the mitochondrial toxin malonate are reduced by 70-80% in transgenic HD mice compared with wild-type littermate controls. This occurred in 6- and 12-week-old HID mice with 150 CAG repeats (line R6/2) and in 18-week-old, but not 6-week-old, HID mice with 115 CAG repeats (line R6/1). Therefore, we show for the first time that the resistance to neurotoxin in transgenic HD mice is dependent on both the CAG repeat length and the age of the mice. Importantly, most HD patients develop symptoms in adulthood and exhibit an inverse relationship between GAG repeat length and age of onset. Transgenic mice expressing a normal CAG repeat (18 CAG) were not resistant to malonate. Although endogenous glutamate release has been implicated in malonate-induced cell death, glutamate release from striatal synaptosomes was not decreased in HID mice. Malonate-induced striatal cell death was reduced by 50-60% in wild-type mice when they were treated with either the NMDA receptor antagonist MK-801 or the caspase inhibitor zVAD-fmk. These two compounds did not reduce lesion size in transgenic R6/1 mice. This might suggest that NMDA receptor- and caspase-mediated cell death pathways are inhibited and that the limited malonate-induced cell death still occurring in HID mice is independent of these pathways. There were no changes in striatal levels of the two anti cell death proteins Bcl-X-L and X-linked Inhibitor of apoptosis protein (XIAP), before or after the lesion in transgenic HD mice. We propose that mutant huntingtin causes a sublethal grade of metabolic stress which is CAG repeat length-dependent and results in up-regulation over time of cellular defense mechanisms against impaired energy metabolism and excitotoxicity.
4.
5.
Ahn, Young Hwan, et al.
(author)
Ultrastructural characterization of dissociated embryonic ventral mesencephalic tissue treated with neuroprotectants.
2003
In: Cell Transplantation. - 1555-3892. ; 12:3, s. 235-241
Journal article (peer-reviewed) abstract
Poor survival and differentiation of grafted dopamine neurons limits the application of clinical transplantation in Parkinson’s disease. The survival of grafted dopamine neurons is only improved by a factor of 2–3 by adding neuroprotectants during tissue preparation. We used dye exclusion cell viability and electron microscopy to investigate the effects of the caspase inhibitor ac-YVAD-cmk and the lazaroid tirilazad mesylate on ultrastructural changes in dissociated embryonic mesencephalic cells. In addition, we examined whether the neuroprotectants selectively counteracted specific signs of neurodegeneration. Cell viability decreased significantly over time in both control and treated cell suspensions, but the number of viable cells remaining was significantly higher in tirilazad mesylate-treated cell suspensions. In control samples, the proportion of cells with an ultrastructure consistent with healthy cells decreased from 70%, immediately after dissociation, to 30% after 8 h of incubation. Similar changes were also observed in cell suspensions treated with neuroprotectants. Thus, the neuroprotectants examined did not block the development of specific morphological signs of neurodegeneration. However, when also taking into account that dead cells lysed and disappeared from each cell suspension with time, we found that the total number of remaining viable cells with healthy nuclear chromatin or intact membrane integrity was significantly higher in the tirilazad mesylate-treated group. The results indicate that tirilazad mesylate protects only a small subpopulation of embryonic mesencephalic cells from degeneration induced by mechanical trauma during tissue dissection and dissociation.
6.
Angot, Elodie, et al.
(author)
Alpha-Synuclein Cell-to-Cell Transfer and Seeding in Grafted Dopaminergic Neurons In Vivo.
2012
In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:6
Journal article (peer-reviewed) abstract
Several people with Parkinson's disease have been treated with intrastriatal grafts of fetal dopaminergic neurons. Following autopsy, 10-22 years after surgery, some of the grafted neurons contained Lewy bodies similar to those observed in the host brain. Numerous studies have attempted to explain these findings in cell and animal models. In cell culture, α-synuclein has been found to transfer from one cell to another, via mechanisms that include exosomal transport and endocytosis, and in certain cases seed aggregation in the recipient cell. In animal models, transfer of α-synuclein from host brain cells to grafted neurons has been shown, but the reported frequency of the event has been relatively low and little is known about the underlying mechanisms as well as the fate of the transferred α-synuclein. We now demonstrate frequent transfer of α-synuclein from a rat brain engineered to overexpress human α-synuclein to grafted dopaminergic neurons. Further, we show that this model can be used to explore mechanisms underlying cell-to-cell transfer of α-synuclein. Thus, we present evidence both for the involvement of endocytosis in α-synuclein uptake in vivo, and for seeding of aggregation of endogenous α-synuclein in the recipient neuron by the transferred α-synuclein. Finally, we show that, at least in a subset of the studied cells, the transmitted α-synuclein is sensitive to proteinase K. Our new model system could be used to test compounds that inhibit cell-to-cell transfer of α-synuclein and therefore might retard progression of Parkinson neuropathology.
7.
Anisimov, Sergey, et al.
(author)
Identification of molecules derived from human fibroblast feeder cells that support the proliferation of human embryonic stem cells.
2011
In: Cellular & Molecular Biology Letters. - : Walter de Gruyter GmbH. - 1689-1392. ; 16:1, s. 79-88
Journal article (peer-reviewed) abstract
The majority of human embryonic stem cell lines depend on a feeder cell layer for continuous growth in vitro, so that they can remain in an undifferentiated state. Limited knowledge is available concerning the molecular mechanisms that underlie the capacity of feeder cells to support both the proliferation and pluripotency of these cells. Importantly, feeder cells generally lose their capacity to support human embryonic stem cell proliferation in vitro following long-term culture. In this study, we performed large-scale gene expression profiles of human foreskin fibroblasts during early, intermediate and late passages using a custom DNA microarray platform (NeuroStem 2.0 Chip). The microarray data was validated using RT-PCR and virtual SAGE analysis. Our comparative gene expression study identified a limited number of molecular targets potentially involved in the ability of human neonatal foreskin fibroblasts to serve as feeder cells for human embryonic stem cell cultures. Among these, the C-KIT, leptin and pigment epithelium-derived factor (PEDF) genes were the most interesting candidates.
8.
Araujo, IM, et al.
(author)
Calpain activation is involved in early caspase-independent neurodegeneration in the hippocampus following status epilepticus
2008
In: Journal of Neurochemistry. - : Wiley. - 1471-4159 .- 0022-3042. ; 105:3, s. 666-676
Journal article (peer-reviewed) abstract
Evidence for increased calpain activity has been described in the hippocampus of rodent models of temporal lobe epilepsy. However, it is not known whether calpains are involved in the cell death that accompanies seizures. In this work, we characterized calpain activation by examining the proteolysis of calpain substrates and in parallel we followed cell death in the hippocampus of epileptic rats. Male Wistar rats were injected with kainic acid (KA; 10 mg/kg) intraperitoneally and sacrificed 24h later, after development of grade 5 seizures. We observed a strong Fluoro-Jade labelling in the CA1 and CA3 areas of the hippocampus in the rats that received KA, as compared to saline-treated rats. Immunohistochemistry and Western blot analysis for the calpain-derived breakdown products of spectrin (SBDP) showed evidence of increased calpain activity in the same regions of the hippocampus where cell death is observed. No evidence was found for caspase activation, in the same conditions. Treatment with the calpain inhibitor MDL 28170 significantly prevented the neurodegeneration observed in CA1. Taken together, our data suggest that early calpain activation, but not caspase activation, is involved in neurotoxicity in the hippocampus after status epilepticus.
9.
10.
Barker, Roger A., et al.
(author)
A new approach to disease-modifying drug trials in Parkinson's disease
2013
In: Journal of Clinical Investigation. - 0021-9738. ; 123:6, s. 2364-2365
Journal article (other academic/artistic) abstract
Translating new findings in the laboratory into therapies for patients is a slow and expensive process. The development of therapies for neurodegenerative diseases is further complicated by the difficulty in determining whether the drug truly retards the slow degenerative process or provides only symptomatic benefit. In this issue, Aviles-Olmos et al. describe a first in Parkinson's disease (PD) patient study using a drug previously approved for diabetes treatment. In addition to suggesting that the drug may indeed be disease modifying in PD, their innovative approach suggests there may be more rapid and inexpensive avenues for testing novel therapies in PD.
