实验性变应性猴脑脊髓炎的超微结构改变

目的探讨自身免疫性中枢神经系统（ＣＮＳ）脱髓鞘的病理特点和发病过程。方法建立猴实验性变态反应性脑脊髓炎（ＥＡＥ）的模型，并从病情不同阶段进行病理取材和电镜观察。结果（１）ＥＡＥ脱髓鞘最早的靶是少突胶质细胞（ＯＤＣ），而不是髓鞘本身；（２）无论急性期还是慢性期，脱髓鞘病灶内只有极少的炎细胞浸入；（３）急性期髓鞘改变轻微，以变性为主，ＯＤＣ肿胀显著，轴突相对完整。远离髓鞘变性区有大量炎细胞浸入；（４）慢性期病变区髓鞘脱失明显，ＯＤＣ严重变性或部分丢失，继发性轴突变性，边缘可见少量薄的髓鞘再生，血脑屏障破坏。结论ＥＡＥ的ＣＮＳ脱髓鞘过程首先累及ＯＤＣ。     

Pelizaeus-Merzbacher病

Pelizaeus-Merzbacher病为X-连锁隐性遗传的脑白质营养不良病,是Xq13-q22染色体上蛋白脂蛋白基因突变所致,最常见的突变是基因复制。临床疾病谱有严重的新生儿型、相对良性的成人型及2型痉挛性截瘫。除蛋白脂蛋白异常外,还伴有中枢神经系统其它髓鞘蛋白的改变,包括髓鞘碱性蛋白,髓鞘相关糖蛋白等。异常的蛋白脂蛋白影响少突胶质细胞的蛋白功能导致细胞凋亡。一些自发和蛋白脂蛋白基因突变或缺失的转基因动物模型促进进一步认识PMD脱髓鞘病变、髓鞘形成和修补。     

Pelizaeus-Merzbacher病

Pelizaeus-Merzbacher病为X-连锁隐性遗传的脑白质营养不良病,是Xq13-q22染色体上蛋白脂蛋白基因突变所致,最常见的突变是基因复制.临床疾病谱有严重的新生儿型、相对良性的成人型及2型痉挛性截瘫.除蛋白脂蛋白异常外,还伴有中枢神经系统其它髓鞘蛋白的改变,包括髓鞘碱性蛋白,髓鞘相关糖蛋白等.异常的蛋白脂蛋白影响少突胶质细胞的蛋白功能导致细胞凋亡.一些自发和蛋白脂蛋白基因突变或缺失的转基因动物模型促进进一步认识PMD脱髓鞘病变、髓鞘形成和修补.     

炎性脱髓鞘性神经病研究进展

神经系统（ＮＳ）中由炎症介导的脱髓鞘性疾病叫炎性脱髓鞘病神经病（ＩＤＮ）。近年,通过临床神经病学、免疫学、病理学和免疫病理学的协作研究,ＩＤＮ取得了长足进展。一、髓鞘髓鞘是包裹在髓鞘细胞轴突外面的一层膜,即髓鞘有髓鞘细胞的细胞膜组成;目前研究注意髓鞘成分的抗原性,如：髓鞘碱性蛋白（ＭＢＰ）、髓鞘相关醣蛋白（ＭＡＧ）、髓鞘少树突胶质细胞醣蛋白（ＭＯＧ）等。ＭＢＰ的抗原性主要取决于其初级结构。实验研究证明不同种实验动物对氨基酸序列中不同片段产生不同的免疫应答。用牛ＭＢＰ主动免疫实验动物可致实验性变应…     

Olig家族与中枢神经系统疾病

2000年首次被人们发现的Olig基因是编码碱性-螺旋-环-螺旋（basic helix-loop-helix，bHLH）转录因子的一个亚家族，它参与了运动神经元、少突胶质细胞和星形胶质细胞的分化，在中枢神经系统（CNS）髓鞘形成和脱髓鞘疾病中发挥重要作用。在不同类别的胶质瘤中，Olig基因表达不同。此外，Olig基因还与脑缺血损伤密切相关。     

Balo病(附1例临床报道)

Balo病的病理特点是白质髓鞘脱失层与较正常的白质层交叠呈同心圆排列，形成树木年轮或洋葱皮样改变［‘］，故又称同心圆硬化或Balo型白质脑炎，是一罕见的中枢神经系统脱髓鞘性病变，过去必须尸检才能确诊，但近来可依据MRI作为生前诊断。作者等经MRI发现典型同心圆改变的Bal     

少突胶质细胞与再髓鞘化

脱髓鞘疾病是目前世界范围内的一种常见的神经系统疾病,而多发性硬化中的脱髓鞘变化是其中研究比较深入的一种。与多发性硬化患者临床缓解——复发病程相对应的脱髓鞘与再髓鞘化给治疗提供了一些策略,促进脱髓鞘疾病患者的再髓鞘化。鉴于在体内存在少突胶质细胞的前体细胞池,这就对我们提出了如何诱导体内的前体细胞向少突胶质细胞的分化的问题。首先要求我们了解参与再髓鞘化过程的细胞及分子。本文对再髓鞘化过程中的重要的细胞——少突胶质细胞的生物学特性及在髓鞘化过程中的作用作一概述。     

实验性自身免疫性脑脊炎的小胶质细胞和星形胶质细胞反应

目的 确定小胶质细胞和星形胶质细胞在实验性自身免疫性脑脊髓炎（ＥＡＥ）发病及病变发展中的作用。方法 用牛脊髓髓鞘碱性蛋白（ＭＢＰ）免疫豚鼠发生ＥＡＥ,用免疫组化法观察ＥＡＥ不同病期小胶质细胞和星形胶质细胞对炎性脱髓鞘病灶的反应。结果 发生ＥＡＥ的前３天,小胶质细胞即开始激活,在临床症状出现时其数量及激活程度达高峰,并持续至高峰期。恢复期数量逐渐减少,激活程度逐渐减弱。星形胶质细胞在症状高峰期开始激     

多发性硬化髓鞘损伤的发生机制及α-硫辛酸的保护作用

<正>多发性硬化(multiple sclerosis,MS)是一种常见的中枢神经系统(central nervous system,CNS)自身免疫性炎性脱髓鞘疾病,以髓鞘脱失、轴索损伤、不同程度的神经胶质细胞增生及进行性神经功能残疾为主要病变特征[1]。目前髓鞘脱失的确切机制尚不清楚,有研究表明[2-3]MS存在着自由基产生过多、氧     

多发性硬化的免疫研究进展

多发性硬化(multiple sclerosis.MS)是一种病因不明的中枢神经系统(central nervous system,CNS)自身免疫性疾病,以炎性脱髓鞘为主要特征,以髓鞘脱失、神经胶质细胞增生、不同程度的轴索病变为主要病理特点.     

Balo's concentric sclerosis: new observations on lesion development

A 54-year-old woman with a four-month history of progressive neurological illness was found at postmortem examination to have lesions of Balo's concentric sclerosis. Balo lesions were found in several areas scattered widely throughout the central nervous system, including the spinal cord, a previously unreported location, and were studied by histological and ultrastructural methods. Balo lesions consisted of bands of intact myelin alternating with zones of demyelination. These lesions were centered on a perivascular cuff of inflammatory cells. The center of the lesion was the oldest area with the concentric rings of demyelination decreasing in age with increasing distance from the center. The bands of intact myelin comprised mainly remyelinated fibers, were similar to those seen at the edges of chronic active multiple sclerosis plaques, and may have represented the repaired margins of preceding episodes. The occurrence of small foci of acute demyelination centered on perivascular cuffs and other changes typical of both acute and chronic active multiple sclerosis may indicate that the lesion of Balo's concentric sclerosis represents an intermediate stage in the development of an established multiple sclerosis lesion.     

Baló's concentric sclerosis: surviving normal myelin in a patient with a relapsing-remitting dinical course.

Baló's concentric sclerosis is a demyelinating disorder in which bands of demyelination alternate with concentric bands of myelin preservation. The pathogenesis of the lesion is unknown. Previous reports using modern histopathologic techniques have shown the bands of myelin preservation to be comprised of remyelinated or partially demyelinated myelin. Here we report a case of Baló's concentric sclerosis in a 24-year-old East Indian patient with a previous history of relapsing-remitting multiple sclerosis (MS). Pathologically, the bands of myelin preservation showed myelin sheaths of normal thickness, with focal areas of demyelination. The findings, taken together with those of previously reported cases, suggest that Baló's concentric sclerosis is a variant of MS, and the concentric lesion may be an intermediary form in evolution of a chronic active MS plaque. The pathogenesis of this concentric lesion may be explained by periodic suppression of demyelination in the rapidly expanding border, allowing remyelination or only transient incomplete demyelination to occur.     

In vivo effect of sera from animals with chronic relapsing experimental allergic encephalomyelitis on central and peripheral myelin

Summary Sera from guinea pigs with acute or chronic relapsing experimental allergic encephalomyelitis (EAE) were injected into the lumbosacral subarachnoid space of normal recipient rats. Seventeen of 37 sera induced demyelination in the CNS, and 27 of 37 sera caused demyelinated peripheral nerve fibers in the roots. The highest incidence of demyelinating activity of EAE sera was noted in those from donor animals sampled during the early chronic stage of the disease [40–100 days post sensitization (dps)]. Only few sera from animals sampled during the acute and subacute stage (10–40 dps) were able to induce demyelination. Sera from animals sampled between 100 and 200 dps showed a lower incidence of demyelinating activity as compared to those from the early chronic phase of the disease. There was no clear-cut correlation between the serum-demyelinating activity and the severity of the demyelinating disease in the donor animals. The patterns of demyelination in the central as well as peripheral nervous system of recipient animals were characterized by vesicular disruption of myelin or myelin stripping. Myelin degradation was performed mainly by macrophages. In the CNS some astrocytes also contained debris. Astrocytes increased in size, and mitosis of astrocytes was observed. Oligodendrocytes appeared to be unaffected. No demyelination was found when the sera from animals sensitized with CFA alone or with guinea pig liver tissue were injeted into the subarachnoid space of normal recipient rats.Two possible mechanisms of demyelination are diseussed: Antibody-mediated complement-dependent and antibody-dependent cell-mediated demyelination.Supported in part by the Fonds zur Förderung der wissenschaftlichen Forschung, Austria, Project No. S-25/07     

Oligodendrocyte reactions and cell proliferation markers in human demyelinating diseases

We have carried out immunocytochemical reactions using antibodies to markers of oligodendrocytes, astrocytes, microglia and proliferating cells (PCNA) in sections of human brain in a variety of demyelinating conditions and human immunodeficiency virus (HIV) infection. In the acute phases of demyelinating diseases we found marked reactive changes in oligodendrocytes with hyperplasia and an increased cytoplasmic reaction using antibodies to enzymes involved in myelin formation. Proliferative responses were implied by the hyperplasia and the common finding of clusters of two or three adjacent oligodendrocytes at sites of acute myelin dam age. This was borne out by studies using the PCNA antibody which gave negative reactions in normal brain but positive reactions in acute demyelination. Double staining for PCNA and cell markers showed that cells that had entered the cell proliferation cycle were to be found among astrocytes, microglia/macrophages and oligodendrocytes. In chronic demyelinating conditions, numbers of oligodendrocytes were reduced and cells in the proliferative cycle were not present, suggesting that the reactive potential of oligodendrocytes or their precursors and their capacity to respond to demyelination is limited.     

Multiple sclerosis: a role for astroglia in active demyelination suggested by class II MHC expression and ultrastructural study

Central nervous system (CNS) tissue was studied by immunocytochemistry and electron microscopy from three cases of multiple sclerosis (MS) in which evidence of ongoing myelin breakdown could be documented. The study focussed upon the role of glial cells in the pathogenesis of demyelination. In acute MS, demyelination involved the vesicular dissolution of myelin from intact axons and a paucity of fibrillary astrogliosis. Foamy macrophages, many of them probably derived from transformed and recently proliferated microglia, contained recognizable myelin debris and lipid droplets and were abundant throughout the lesions. These cells formed the major phagocytic population and stained positively for class II major histocompatibility complex antigens (HLA-DR; Ia). In acute MS lesions, rounded astrocytes were encountered which possessed membrane-bound compartments enclosing phagocytosed fragments of myelin basic protein-positive debris. Despite the superficial resemblance of these cells to foamy macrophages, the presence of intermediate filaments, glycogen granules and diffuse glial fibrillary acidic protein positivity supported an astroglial identity. Astrocyte processes were involved in myelin removal and invested recently demyelinated axons. Hypertrophic fibrous astrocytes were common in chronic active lesions, were capable of myelin degradation and on occasion, contained myelin debris attached to clathrin-coated pits. These astrocytes were sometimes Ia+. Oligodendrocytes were depleted from the center of active lesions but were numerous at the lesion margin, suggesting survival and proliferation. They stained positively for myelin-associated glycoprotein, a marker for immature oligodendrocytes. However, they were invariably Ia-. The findings confirm and further support a role for the astrocyte as both an antigen presenting cell and a phagocyte in the CNS during MS.     

Inhibition of CXCR2 signaling promotes recovery in models of multiple sclerosis

Multiple sclerosis (MS) is a neurodegenerative disease characterized by demyelination/remyelination episodes that ultimately fail. Chemokines and their receptors have been implicated in both myelination and remyelination failure. Chemokines regulate migration, proliferation and differentiation of immune and neural cells during development and pathology. Previous studies have demonstrated that the absence of the chemokine receptor CXCR2 results in both disruption of early oligodendrocyte development and long-term structural alterations in myelination. Histological studies suggest that CXCL1, the primary ligand for CXCR2, is upregulated around the peripheral areas of demyelination suggesting that this receptor/ligand combination modulates responses to injury. Here we show that in focal LPC-induced demyelinating lesions, localized inhibition of CXCR2 signaling reduced lesion size and enhanced remyelination while systemic treatments were relatively less effective. Treatment of spinal cord cultures with CXCR2 antagonists reduced CXCL1 induced A2B5+ cell proliferation and increased differentiation of myelin producing cells. More critically, treatment of myelin oligodendrocyte glycoprotein peptide 35–55-induced EAE mice, an animal model of multiple sclerosis, with small molecule antagonists against CXCR2 results in increased functionality, decreased lesion load, and enhanced remyelination. Our findings demonstrate the importance of antagonizing CXCR2 in enhancing myelin repair by reducing lesion load and functionality in models of multiple sclerosis and thus providing a therapeutic target for demyelinating diseases.     

Immunocytochemical study of Myelin-associated Glycoprotein (MAG) and Basic Protein (BP) in acute Experimental Allergic Encephalomyelitis (EAE)

To compare distributions of oligodendroglial myelin-associated glycoprotein (MAG) and myelin basic protein (BP) during demyelination in acute experimental allergic encephalomyelitis (EAE). Lewis rats were sensitized with an emulsion containing guinea pig spinal cord and complete Freund's adjuvant. The rats were examined clinically and groups were perfused with fixative before symptoms appeared (7d), within 48 h of symptom onset (10d) and during more severe illness (14d, 21d). Paraffin sections of cerebrum, brainstem, and spinal cord were immunostained with antisera to MAG and BP. Other sections in each serially mounted series were stained with luxol fast blue, hematoxylin and eosin or with the Bodian method to correlate MAG and BP results with histological changes. No abnormalities were detected 7d after sensitization. After 10d, small perivenular inflammatory cell infiltrates were present in white matter, displaced myelinated fibers, but their MAG stained periaxonal regions and BP-stained myelin sheaths appeared normal. In pontine grey matter lesions, there were focal abnormalities in a few myelin sheaths. After 21d, demyelinating lesions were present that were largest in pontine grey matter. Decreased MAG staining was present in areas of myelin sheath loss. MAG-stained fragments were found in zones of active myelin breakdown but no decrease or other change in MAG staining extended beyond the margins of demyelinating lesions into areas with normally stained myelin sheaths. Thus, in contrast to multiple sclerosis (Itoyama et al. 1980), changes in periaxonal oligodendroglial MAG are not present in acute EAE before inflammatory cell infiltrates or myelin sheath changes appear. Our findings suggest that myelin sheaths are the primary targets in EAE-induced demyelination. Oligodendroglia appear to be relatively unaffected and are available to remyelinate axons.     

Fine structure of astrocytic processes during serum-induced demyelination in vitro

Astrocytic changes were examined ultrastructurally during serum-induced demyelination in organotypic cultures of mouse spinal cord tissue. The myelin sheaths of most myelinated fibers showed myelin breakdown. Sheet-like astrocytic processes completely and closely surrounded the demyelinating fibers and frequently engulfed myelin fragments. These processes were virtually devoid of glial filaments or microtubules and contained flocculogranular material, round and elongated cisterns and glycogen granules. Penetration of the myelin sheath by astrocytic processes was only rarely found. The cell body of the astrocyte was never insinuated between the myelin sheath and the axon. No endocytosis of myelin droplets via coated pits on the surface of astrocytes was observed. In comparison with phagocytic mononuclear cells in vivo, astrocytes in vitro dispose of myelin debris less actively. Astrocytes in serum-induced demyelination probably play a nonspecific but fundamental role during degeneration in segregating damaged nerve fibers from surrounding neuronal elements.     

Tumour-like lesions in multiple sclerosis

The presence of tumefactive lesions on magnetic resonance imaging (MRI) in multiple sclerosis (MS) patients can cause diagnostic difficulties. It requires differential diagnosis between tumefactive demyelinating lesion (TDL) and the coexistence of neoplasm; it also implies further management. The precise assessment of such lesions at the first clinical manifestation of the disease is particularly important. We present three cases of MS presenting with tumour-like lesions of the brain. Based on serial MRI studies, stereotactic biopsy and the response to treatment with corticosteroids, the diagnosis of TDL was established in every case.     

Concentric sclerosis (Baló): Morphometric and in situ hybridization study of lesions in six patients

Brain tissues from 6 patients with concentric sclerosis (Baló) were examined by in situ hybridization, immunocytochemistry, morphometry, and histological methods. The patients were 24 to 48 years old and had progressive cerebral symptoms and signs that lasted 15 to 100 days. Large demyelinative lesions, most frequent in the frontal white matter, contained alternating bands of demyelinated and partly myelinated white matter that were arranged in concentric or mosaic patterns. In the areas of demyelination, axons were relatively well preserved and there were perivascular inflammatory infiltrates. In 2 specimens, lesions contained regions with the characteristic appearance of actively demyelinating multiple sclerosis plaques. Oligodendroglial densities were highest in normal-appearing white matter, lower in partially myelinated areas, and lowest in demyelinated areas, which also contained many hypertrophic astrocytes closely associated with oligodendroglia. Messenger RNA levels for myelin-related proteins followed the same pattern; they were lowest in demyelinated areas, higher in partially myelinated areas, and highest in normal-appearing white matter beyond lesion margins. Our findings suggest that concentric sclerosis is a variant of multiple sclerosis, that oligodendroglial loss is important in the pathogenesis of demyelination, and that partially myelinated areas probably represent stages of ongoing myelin breakdown rather than remyelination of previously demyelinated areas.