Comparative gene expression profiling of olfactory ensheathing cells from olfactory bulb and olfactory mucosa

Olfactory ensheathing cells (OEC) have the ability to promote regeneration in the nervous system. Hence, they hold promise for cell therapy. Most of the experimental studies have investigated the role of OECs taken from olfactory bulb (OB). However, for a clinical human application, olfactory mucosa (OM) seems to be the only acceptable source for OECs. Many studies have compared the distinct ability of OECs from OB and OM to improve functional nerve regeneration after lesion of the nervous system. Nevertheless, the two populations of OECs may differ in several points, which might affect all fate after transplantation in vivo. We report here the first study which compares gene expression profiling between these two populations of OECs. It appears that OB‐OECs and OM‐OECs display distinct gene expression pattern, which suggest that they may be implicated in different physiological processes. Notably, OM‐OECs overexpress genes characteristic of wound healing and regulation of extra cellular matrix. In contrast, OB‐OECs gene profile suggests a prominent role in nervous system development. Hence, OB‐OECs and OM‐OECs fundamentally differ in their gene expression pattern, which may represent a crucial point for future clinical application. © 2010 Wiley‐Liss, Inc.     

神经变性疾病脑脊液生物学标志物研究进展

中枢神经系统变性疾病是一类临床表型复杂、难以早期诊断与鉴别诊断的疾病群,发病隐匿且多呈慢性进行性发展,早期诊断、早期治疗十分关键。探寻神经变性疾病特异性的脑脊液生物学标志物,对指示或评价特定神经变性损害,以及对此类疾病的早期诊断与鉴别诊断有重要价值。本文就脑脊液生物学标志物在常见神经变性疾病(多发性硬化、阿尔茨海默病、帕金森病、肌萎缩侧索硬化症等)中的研究现状,以及对疾病诊断与鉴别诊断的辅助价值进行概述。     

Differential expression and distribution of alpha-, beta-, and gamma-synuclein in the developing human substantia nigra

Although the functions of alpha-, beta-, and gamma-synuclein (alphaS, betaS, gammaS, respectively) are unknown, these synaptic proteins are implicated in the pathogenesis of Parkinson's disease (PD) and related disorders. For example, alphaS forms Lewy bodies (LBs) in substantia nigra (SN) neurons of PD. However, since it is not known how these hallmark PD lesions contribute to the degeneration of SN neurons or what the normal function of alphaS is in SN neurons, we studied the developing human SN from 11 weeks gestational age (GA) to 16 years of age using immunohistochemistry and antibodies to alphaS, betaS, gammaS, other synaptic proteins, and tyrosine hydoxylase (TH). SN neurons expressed TH at 11 weeks GA and alphaS, betaS, and gammaS appeared initially at 15, 17, and 18 weeks GA, respectively. These synucleins first appeared in perikarya of SN neurons after synaptophysin, but about the same time as synaptotagmin and synaptobrevin. Redistribution of alphaS from perikarya to processes of SN neurons occurred by 18 weeks GA in parallel with synaptophysin, while betaS and synaptotagmin were redistributed similarly between 20 and 28 weeks GA and this also occurred with gammaS and synaptobrevin between 33 weeks GA and 9 months postnatal. These data suggest that alphaS, betaS, and gammaS may play a functional role in the development and maturation of SN neurons, but it remains to be determined how sequestration of alphaS as LBs in PD contributes to the degeneration of SN neurons.     

Reduced cholinergic olfactory centrifugal inputs in patients with neurodegenerative disorders and MPTP-treated monkeys

Olfactory impairment is a common feature of neurodegenerative diseases such as Parkinson’s disease (PD), Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB). Olfactory bulb (OB) pathology in these diseases shows an increased number of olfactory dopaminergic cells, protein aggregates and dysfunction of neurotransmitter systems. Since cholinergic denervation might be a common underlying pathophysiological feature, the objective of this study was to determine cholinergic innervation of the OB in 27 patients with histological diagnosis of PD (n = 5), AD (n = 14), DLB (n = 8) and 8 healthy control subjects. Cholinergic centrifugal inputs to the OB were clearly reduced in all patients, the most significant decrease being in the DLB group. We also studied cholinergic innervation of the OB in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys (n = 7) and 7 intact animals. In MPTP-monkeys, we found that cholinergic innervation of the OB was reduced compared to control animals (n = 7). Interestingly, in MPTP-monkeys, we also detected a loss of cholinergic neurons and decreased dopaminergic innervation in the horizontal limb of the diagonal band, which is the origin of the centrifugal cholinergic input to the OB. All these data suggest that cholinergic damage in the OB might contribute, at least in part, to the olfactory dysfunction usually exhibited by these patients. Moreover, decreased cholinergic input to the OB found in MPTP-monkeys suggests that dopamine depletion in itself might reduce the cholinergic tone of basal forebrain cholinergic neurons.     

Glial HO-1 expression,iron deposition and oxidative stress in neurodegenerative diseases

The mechanisms responsible for the pathological deposition of brain iron in Parkinson's disease, Alzheimer's disease and other human neurodegenerative disorders remain poorly understood. In rat primary astrocyte cultures, we demonstrated that dopamine, cysteamine, H(2)O(2) and menadione rapidly induce heme oxygenase-1 (HO-1) expression (mRNA and protein) followed by sequestration of non-transferrin-derived (55)Fe by the mitochondrial compartment. The effects of dopamine on HO-1 expression were inhibited by ascorbate implicating a free radical mechanism of action. Dopamine-induced mitochondrial iron trapping was abrogated by administration of the heme oxygenase inhibitors, tin mesoporphyrin (SnMP) or dexamethasone (DEX) indicating that HO-1 upregulation is necessary for subsequent mitochondrial iron deposition in these cells. Overexpression of the human HO-1 gene in cultured rat astroglia by transient transfection also stimulated mitochondrial (55)Fe deposition, an effect that was again preventible by SnMP or DEX administration. We hypothesize that free ferrous iron and carbon monoxide generated by HO-1-mediated heme degradation promote mitochondrial membrane injury and the deposition of redox-active iron within this organelle. We have shown that the percentages of GFAP-positive astrocytes that co-express HO-1 in Parkinson-affected substantia nigra and Alzheimer-diseased hippocampus are significantly increased relative to age-matched controls. Stress-induced up-regulation of HO-1 in astroglia may be responsible for the abnormal patterns of brain iron deposition and mitochondrial insufficiency documented in various human neurodegenerative disorders.     

Increased dopaminergic cells and protein aggregates in the olfactory bulb of patients with neurodegenerative disorders

Olfactory dysfunction is a frequent and early feature of patients with neurodegenerative disorders such as Alzheimer’s disease (AD) and Parkinson’s disease (PD) and is very uncommon in patients with frontotemporal dementia (FTD). Mechanisms underlying this clinical manifestation are poorly understood but the premature deposition of protein aggregates in the olfactory bulb (OB) of these patients might impair its synaptic organization, thus accounting for the smell deficits. Tau, β-amyloid and alpha-synuclein deposits were studied in 41 human OBs with histological diagnosis of AD (n = 24), PD (n = 6), FTD (n = 11) and compared with the OB of 15 control subjects. Tau pathology was present in the OB of all patients, irrespective of the histological diagnosis, while β-amyloid and alpha-synuclein protein deposit were frequently observed in AD and PD, respectively. Using stereological techniques we found an increased number of dopaminergic periglomerular neurons in the OB of AD, PD and FTD patients when compared with age-matched controls. Moreover, volumetric measurements of OBs showed a significant decrease only in AD patients, while the OB volume was similar to control in PD or FTD cases. The increased dopaminergic tone created in the OBs of these patients could reflect a compensatory mechanism created by the early degeneration of other neurotransmitter systems and might contribute to the olfactory dysfunction exhibited by patients with neurodegenerative disorders.     

人嗅粘膜嗅鞘细胞的分离、培养及生物学特性

目的细胞移植是目前的研究热点,本文主要研究人嗅粘膜嗅鞘细胞(OM-OECS)的分离、培养、纯化、鉴定,来观察其生长情况,分析其生物学特性,为具有神经功能障碍的患者实行同种细胞移植提供一种可行的方法。方法选取意外交通事故或意外疾病、事故急性死亡3h内及经蝶窦手术的患者,征得家属同意,取鼻中隔后1/3鼻粘膜,免疫吸附法结合采用P75抗体包被的培养皿进行纯化人OM-OECs,免疫组化方法进行细胞的鉴定。结果 OM-OECs体外培养过程中,采用免疫吸附法使抗体与间充质来源的成纤维细胞进行特异结合从而将其去除,P75抗体包被的培养皿促进了OECs的贴壁使其与杂质细胞进一步分离,在体外培养10d后,细胞增殖最快,经P75、GFAP免疫组化双标染色显示呈双阳性,计数阳性细胞率达90%以上,说明从人嗅粘膜分离培养OECs具有较高的纯度。结论从人鼻粘膜取材,可以分离培养出OECs,体外生长增殖旺盛,并且经纯化后具有较高的纯度。     

The olfactory bulb and olfactory mucosa obtained from human cadaver donors as a source of olfactory ensheathing cells

During the last decade, olfactory ensheathing cells (OECs) have been successfully applied in multiple experimental approaches aimed to repair damaged mammalian spinal cord. Some of these experiments have consequently been translated into clinical trials. Finding a reliable source of human OECs that is easily accessible and can ensure a sufficient number of cells is a major prerequisite for conducting studies on OEC-mediated spinal cord regeneration. Here, we present a procedure for obtaining olfactory bulbs (OBs) and olfactory mucosa (OM) simultaneously from adult cadaver heart-beating donors for OEC isolation and analyze some of the factors that may condition successful OEC culture. We show that the results of OEC culture from OBs (10 cases) correlated significantly with warm ischemia time (WIT) as well as the initial viability of the isolated cells. Efficient OEC culture was possible when the WIT for the OB was up to 20 min. Brain damage, assessed by determination of S100B serum level, was not related to the success of OEC culture from the OB. Cadaver OM (7 cases) was shown to be a more reliable source of human OECs than the OB. In most of the examined cases the efficacy of culturing OECs from cadaver OM obtained even 180 min after cardiac arrest was comparable to that of living patients. The method of obtaining OBs and OM from cadavers enables the use of an alternative source of primary adult human OECs for further preclinical and clinical studies on their neurotrophic properties.     

The olfactory mucosa,first actor of olfactory detection,is sensitive to glucocorticoid hormone

The olfactory mucosa (OM) is the primary site of odorant detection, and its axonal projections relay information to brain structures for signal processing. We have previously observed that olfactory function can be affected during a prolonged stress challenge in Wistar rats. The stress response is a neuroendocrine retro‐controlled loop allowing pleiotropic adaptive tissue alterations, which are partly mediated through the release of glucocorticoid hormones. We hypothesised that, as part of their wide‐ranging pleiotropic effects, glucocorticoids might affect the first step of olfactory detection. To study this, we used a number of approaches ranging from the molecular detection and functional characterisation of glucocorticoid receptors (GRs) in OM cells, to the study of GR acute activation in vivo at the molecular, electrophysiological and behavioural levels. In contrast to previous reports, where GR was reported to be exclusive in olfactory sensory neurones, we located functional GR expression mostly in olfactory ensheathing cells. Dexamethasone (2 mg/kg) was injected intraperitoneally to activate GR in vivo, and this led to functional odorant electrophysiological response (electro‐olfactogram) and OM gene expression changes. In a habituation/cross‐habituation test of olfactory sensitivity, we observed that DEX‐treated rats exhibited higher responsiveness to a complex odorant mixture. These findings support the idea that olfactory perception is altered in stressed animals, as glucocorticoids might enhance odour detection, starting at the first step of detection.     

The role of osteopontin in neurodegenerative diseases

Osteopontin (OPN) was shown to be involved in inflammatory and degenerative processes of the nervous system. In multiple sclerosis, the role of OPN has been studied in the inflammatory phase, where it was shown that the protein levels increase during disease relapses. Moreover, it was shown that subjects who carry a genotype associated with decreased protein levels tend to display a benign course. Taken altogether, these findings suggest that OPN may play a detrimental role in multiple sclerosis, at least in the inflammatory phase. In common neurodegenerative diseases, such as Parkinson's and Alzheimer's disease, OPN seems to act as a double-edged sword triggering neuronal toxicity and death in some contexts and functioning as a neuroprotectant in others. The involvement of OPN in several biological pathways and networks calls for more extensive research in order to unravel its role in the different disease phases and its potential as a therapeutic target.     

The role of cannabinoids in neurodegenerative diseases

An understanding of the actions of Cannabis (Marijuana) has evolved from folklore to science over the previous hundred years. This progression was spurred by the discovery of an endogenous cannabinoid system consisting of two receptors and two endogenous ligands. This system appears to be intricately involved in normal physiology, specifically in the control of movement, formation of memories and appetite control. As we are developing an increased understanding of the physiological role of endocannabinoids it is becoming clear that they may be involved in the pathology of several neurological diseases. Furthermore an array of potential therapeutic targets is being determined--including specific cannabinoid agonists and antagonists as well as compounds that interrupt the synthesis, uptake or metabolism of the endocannabinoids. This article reviews the recent progress in understanding the contribution of endocannabinoids to the pathology and therapy of Huntington's disease. Parkinson's disease, schizophrenia and tremor.     

The role of autophagy in neurodegenerative diseases

Autophagy is a process where cytoplasmic components of the cell are transported into the lysosomes and degraded. Autophagy is a complex process that is necessary for the normal functioning of any eukaryotic cell. The neurons are among the cells that are the most sensitive to dysfunction of autophagy. Impaired autophagy at different stages leads to a wide variety of neurodegenerative diseases. In this review, we discuss the stages and underlying molecular mechanisms of autophagy in detail and present the data that concern how impairments at one or more of these stages lead to the development of neurodegenerative diseases. The possibility of applying different therapeutic strategies of autophagy modulation for treatment of neurodegenerative diseases is discussed.     

The role of mitochondria in neurodegenerative diseases

Mitochondria are implicated in several metabolic pathways including cell respiratory processes, apoptosis, and free radical production. Mitochondrial abnormalities have been documented in neurodegenerative diseases, including Alzheimer’s, Parkinson’s, and Huntington’s diseases, and amyotrophic lateral sclerosis. Several studies have demonstrated that mitochondrial impairment plays an important role in the pathogenesis of this group of disorders. In this review, we discuss the role of mitochondria in the main neurodegenerative diseases and review the updated knowledge in this field.     

Somatosensory-related gamma-, beta- and alpha-augmentation precedes alpha- and beta-attenuation in humans

ObjectiveSeveral human studies have demonstrated that the amplitudes of cortical oscillations are altered by various sensorimotor and cognitive tasks. Event-related augmentation of gamma oscillations and attenuation of alpha and beta oscillations have been often used as surrogate markers of cortical activation elicited by tasks especially in presurgical identification of eloquent cortices. In the present study, we addressed a question whether somatosensory-related gamma augmentation ‘precedes’ or ‘co-occurs with’ somatosensory-related attenuation of alpha–beta oscillations.MethodsWe studied 10 patients who underwent intracranial electrocorticography for epilepsy surgery, and determined the temporal and spatial characteristics of median-nerve somatosensory-related amplitude changes at gamma- (30–100 Hz), beta- (14–28 Hz) and alpha-band (8–12 Hz) oscillations.ResultsWe found that somatosensory-related gamma augmentation involving the post- and pre-central gyri evolved into beta and alpha augmentation, which was subsequently followed by beta and alpha attenuation involving the post- and pre-central gyri.ConclusionsThese observations support the hypothesis that somatosensory-related gamma augmentation but not alpha–beta attenuation represents the initial cortical processing for external somatosensory stimuli. Somatosensory-related alpha–beta attenuation appears to represent a temporally distinct stage of somatosensory processing.SignificanceThe present study has increased our understanding of event-related gamma augmentation and alpha–beta attenuation seen on electrocorticography.     

Distribution of alpha- and gamma-synucleins in the adult rat brain and their modification by high-dose cocaine treatment

Synucleins have attracted much attention because of their involvement in several neurodegenerative disorders. In a screening for genes differentially expressed after high-dose cocaine exposure, we found gamma-synuclein as a major upregulated candidate in the tegmentum. Overexpression of both alpha- and gamma-synuclein after drug treatment was confirmed by means of microarrays, yielding an increase in the hippocampus, the striatum and the tegmentum (2.65 x, 1.96 x and 3.5 x, respectively, for alpha-synuclein vs. 2.7 x, 1.96 x and 7.16 x for gamma-synuclein), but no change in the nucleus accumbens. Investigation of the distribution of mRNA (by in situ hybridization) and of the proteins (by immunocytochemistry) shows in both cases a clearly distinct pattern of expression for alpha- and gamma-synuclein. alpha-synuclein displays a very characteristic distribution, confined to specific nuclei, whereas gamma-synuclein is more widely expressed throughout the brain. mRNA of both alpha- and gamma-synucleins display a complementary pattern of expression all over the cortex. In contrast to gamma-synuclein, alpha-synuclein is neuronal, being only found in NeuN-expressing cells, and is expressed in the basal ganglia (faintly) and in the substantia nigra compacta where it is highly correlated with tyrosine hydroxylase. Immunocytochemistry shows that gamma-synuclein generally colocalizes with glial fibrillary acidic protein-expressing cells and is abundant in the red nucleus, the substantia nigra reticulata and the anterior commissure, while gamma-synuclein mRNA labels the matrix compartments of the caudate-putamen. The role of synucleins in relation to cocaine-induced plasticity or neurotoxicity is discussed.     

The genetic causes of neurodegenerative diseases

With the application of molecular genetics, we are now beginning to understand the etiology and the early stages of pathogenesis of the major neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Pick's disease and Progressive Supranuclear Palsy. Surprisingly, these studies are showing that these diseases share pathogenic mechanisms which involve tau or synuclein aggregation. In this article, I review the progress in the molecular genetic analysis of these major neurodegenerative diseases and discuss how they are related to each other.     

Aging,energy, and oxidative stress in neurodegenerative diseases

The etiology of neurodegenerative diseases remains enigmatic; however, evidence for defects in energy metabolism, excitotoxicity, and for oxidative damage is increasingly compelling. It is likely that there is a complex interplay between these mechanisms. A defect in energy metabolism may lead to neuronal depolarization, activation of N-methyl-D-aspartate excitatory amino acid-receptors, and increases in intracellular calcium, which are buffered by mitochondria. Mitochondria are the major intracellular source of free radicals, and increased mitochondrial calcium concentrations enhance free radical generation. Mitochondrial DNA is particularly susceptible to oxidative stress, and there is evidence of age-dependent damage and deterioration of respiratory enzyme activities with normal aging. This may contribute to the delayed onset and age dependence of neurodegenerative diseases. There is evidence for increased oxidative damage to macromolecules in amyotrophic lateral sclerosis, Huntington's disease, Parkinson's disease, and Alzheimer's disease. Potential therapeutic approaches include glutamate release inhibitors, excitatory amino acid antagonists, strategies to improve mitochondrial function, free radical scavengers, and trophic factors. All of these approaches appear promising in experimental studies and are now being applied to human studies.     

The neuropathology of sleep in human neurodegenerative diseases

The neuropathology of human sleep remains an ill-defined issue. The data concerning the main structures of human brain areas involved, or supposed to be implicated, in sleep organisation are reviewed. Five levels of organisation can be schematically recognized: (i) the ascending arousal system, (ii) the non REM and REM systems (iii) regulated by hypothalamic areas, (iv) and the biological clock, (v) modulated by a number of "allostatic" influences. These are briefly described, with emphasis on the location of structures involved in humans, and on the recently revised concepts. Current knowledge on the topography of lesions associated with the main sleep disorders in degenerative diseases is recalled, including REM sleep behavior disorders, restless legs syndrome and periodic leg movements, sleep apneas, insomnia, excessive daily sleepiness, secondary narcolepsy and disturbed sleep-wake rhythms. The lesions of sleep related structures observed in early and late stages of four degenerative diseases are then reviewed. Two synucleinopathies (Lewy lesions associated disorders, including Parkinson's disease and Dementia with Lewy bodies, and Multiple System Atrophy) and two tauopathies (Progressive Supranuclear Palsy and Alzheimer's disease) are dealt with. The distribution of lesions usually found in affected patients fit with that expected from the prevalence of different sleep disorders in these diseases. This confirms the current opinion that these disorders depend on the distribution of lesions rather than on their biochemical nature. Further studies might throw insight on the mechanism of normal and pathological sleep in humans, counterpart of the increasing knowledge provided by animal models. Specially designed prospective clinicopathological studies including peculiar attention to sleep are urgently needed.     

The prevalence of misidentification syndromes in neurodegenerative diseases

Although misidentification syndromes (MISs) have been often described in Alzheimer disease (AD), the prevalence of these phenomena in different neurodegenerative diseases has not been systematically studied. Three hundred ninety-two individuals with probable AD, 119 patients with the behavioral variety of frontotemporal dementia (FTD-bv), 101 patients with primary progressive aphasia, 24 subjects with semantic dementia, 18 subjects with corticobasal degeneration, 8 patients with progressive supranuclear palsy, 36 individuals with probable Lewy body dementia (DLB), and 26 subjects with Parkinson disease (PD) were the participants of this study. On the basis of a semistructured interview with both patients and their reliable caregivers, MIS was identified in 15.8% of cases with AD, 16.6% of patients with DLB, and in 8.3% of individuals with semantic dementia. The most frequent form of MIS was Capgras delusions, often accompanied by reduplication of place, phantom border phenomenon, or both. Although MIS typically appears in later stages of the disease, it can also occur surprisingly early in patients with AD. None of the patients with FTD-bv, primary progressive aphasia, corticobasal degeneration/supranuclear palsy, or PD developed MIS. Thus, our findings suggest that MISs are characteristic of AD and DLB, and tend to exclude FTD/Pick complex and PD.