Complement in central nervous system inflammation

The complement system is well represented in the central nervous system. Glial cells and neurons produce or express all of the activation and regulatory proteins and the C3a/C5a receptors. Inhibition of complement activation is protective in experimental allergic encephalomyelitis, the animal model for multiple sclerosis, suggesting possible therapeutic approaches for human disease. New findings indicate that the C3a/C5a receptors are widely expressed in neurons and may modulate neuronal function.     

Involvement of the central nervous system in malignant lymphomas

Summary A retrospective histologic study of 145 consecutive autopsy cases of systemic malignant lymphomas (including lymphatic leukemias) was performed. The classification followed the Kiel Classification (Gérard-Marchant et al., 1974). There was an overall secondary CNS involvement in 26.2% of the total or in 30.4% of the non-Hodgkin's lymphomas including ALL, with intracranial lesions in 21.4 and 26.1%, respectively, and spinal epidural spread in 5.5 (5.1)%. Peripheral nerve involvement was seen in almost 40% of the examined cases. Ten further cases were isolated (primary) intracranial lymphomas without evidence of extraneural deposits or systemic lymphatic disease. The CNS complications in non-Hodgkin's lymphomas were diffuse meningeal and/or perivascular infiltration with or without invasion of the nervous parenchyma, and did not differ from those in CNS leukemia. Isolated solid mass lesions in the brain were only present in 7% of the secondary CNS lymphomas, but were seen in all instances of primary cerebral lymphomas. The incidence of CNS complications was highest in lymphoblastic lymphomas including ALL (39%), CLL (31%), immunocytic lymphoma (29%), less frequent in immunoblastic (18.7%), and centrocytic lymphomas (16.6%). No intracranial lesion was observed in centroblastic-centrocytic and centroblastic lymphomas which only produced epidural spread. Bone marrow involvement was present in 92.8% of the cases with secondary CNS lesions, and in 83.2% of the epidural lymphomas. Leukemic conversion, present in 44% of the total (52% with ALL), was demonstrated in 83.3% of the cases with secondary brain lesions, but was hardly combined with epidural spread. The histologic pattern of CNS lesions in non-Hodgkin's lymphomas and their frequent association with leukemic conversion suggest the importance of hematogenous dissemination rather than of direct spread from bone marrow or local manifestation in multisystem disease. Isolated (primary) lymphomas of the CNS which are morphologically identical with the extraneural lymphomas may represent a primary, often lethal manifestation of a multisystem disease with or without secondary generalization.     

Arginase and autoimmune inflammation in the central nervous system

Using a high throughput gene microarray technology that detects approximately 22 000 genes, we found that arginase I was the most significantly up-regulated gene in the murine spinal cord during experimental autoimmune encephalomyelitis (EAE). By Northern blot and arginase enzyme assay, we detected high levels of arginase I mRNA and protein, respectively, in the spinal cord of EAE mice, but not in the spinal cord of normal mice or mice that had recovered from EAE. In vitro, both microglia and astrocytes produced arginase and nitric oxide synthase, two enzymes that are involved in arginine metabolism. To explore the roles of arginase in EAE, we injected the arginase inhibitor amino-6-boronohexanoic acid (ABH) into mice during the inductive and effector phases of the disease. Compared with mice that received vehicle control, mice treated with ABH developed milder EAE with delayed onset, reduced disease score and expedited recovery. Spleen mononuclear cells from ABH-treated mice produced more nitric oxide and secreted less interferon-gamma and tumour necrosis factor-alpha as compared to control mice. These results indicate that arginase plays important roles in autoimmune inflammation in the central nervous system.     

Involvement of inflammatory cytokines in central nervous system injury

Pro-inflammatory cytokines, interleukin (IL) 1 and tumor necrosis factor (TNF), possess a wide range of biological actions in various tissues. In recent years, there has been increasing evidence that these cytokines are involved in inflammatory reactions in central nervous system (CNS) diseases. Although many studies have demonstrated that IL-1, TNF, and their mRNA are up-regulated in the CNS after injury, the functional roles of these cytokines in the injury are far from completely understood. Overexpression of these cytokines, such as observed during the early stage of injury, can be harmful for the injured tissue. However, low levels of these cytokines, observed during the recovery stage after injury, can enhance repair processes of the injured tissues.     

Involvement of CD45 in central nervous system myelination

Myelin is a multi-layered membranous lipid insulator surrounding axons that allows the rapid conduction of neuronal impulses. In the central nervous system (CNS), myelin is produced by oligodendrocytes. During development, morphologically immature oligodendrocyte precursor cells (OPCs) arise from neural stem cells before differentiating into myelinating oligodendrocytes shortly after birth. Fyn tyrosine kinase (Fyn) has been shown to play a central role during OPC differentiation, including inducing morphological changes in the cells and initiating the expression of myelin basic protein (MBP), a major structural protein required for the compaction of myelin sheaths. Recently, we have shown that signaling via the gamma chain of immunoglobulin Fc receptors (FcRgamma) induces the Fyn-MBP cascade and promotes the morphological differentiation of OPCs. The protein tyrosine phosphatases that are responsible for the positive regulation of Fyn tyrosine kinase activity during this cascade, however, remained unknown. Here we report that a protein tyrosine phosphatase, CD45, is involved in this process. Fyn co-immunoprecipitated with CD45 from differentiating wild-type OPCs in vitro, while CD45-deficient OPCs failed to differentiate. Additionally, dysmyelination was observed in CD45-deficient mice in vivo. Our findings suggest that CD45 is a key phosphatase involved in OPC differentiation and provide a preliminary explanation for the previously reported CD45 mutations observed in some multiple sclerosis (MS) patients.     

Oral motor deficits following lesions of the central nervous system in the rat.

The effects of lesions of the zona incerta (ZI), globus pallidus (GP), midlateral and far lateral hypothalamus (MLH and FLH), and the central amygdaloid complex (CAC) on oral motor deficits were investigated. Lesions of the ZI, GP, and CAC resulted in a significant reduction in tongue extension and lap volume. MLH lesions significantly reduced tongue extension whereas FLH lesions significantly reduced both tongue extension and lap volume. Injections of 6-hydroxydopamine into the GP, MLH, and CAC also significantly reduced tongue extension and lap volume. Water and/or food intakes were reduced in some of the lesioned groups but the oral motor deficits were observed both in the presence and in the absence of reduced water and food intakes. The possibility that oral motor deficits are associated with damage to striatal and non-striatal dopamine neurons needs further investigation.     

Demyelination and remyelination in the rat central nervous system following ethidium bromide injection

Intracisternal injection of ethidium bromide induced status spongiosus with prominent degenerative changes in oligodendroglia in the subpial regions of the central nervous system of the rat. Chronologic investigation of the lesions has revealed that status spongiosus resulted in myelin degeneration, and by the 6th day postinjection many axons were demyelinated. At this time, numerous debris-filled phagocytic cells were observed among the totally naked axons. Vesicular transformation of myelin was the common degenerative change. Features suggestive of separation of myelin lamellae by phagocytic cells were also observed. In the demyelinated areas, oligodendroglial cells disappeared completely. By the 12th day postinjection, remyelination was apparent and numerous active oligodendroglia appeared in association with thinly myelinated axons. Some central nervous system axons were myelinated by Schwann cells. These patterns of demyelination and remyelination observed in ethidium bromide-treated rats were compared with those observed in other demyelinating conditions of varied etiology such as experimental allergic encephalomyelitis, diphtheria toxin, or lysolecithin injection and cuprizone intoxication.     

Macrophages in the central nervous system of the rat

In an immunohistochemical study using monoclonal antibodies, which exclusively recognize cells of the monocyte-macrophage lineage, and monoclonal antibodies against the Ia-antigen, we describe the occurrence of macrophages in the developing and adult central nervous system (CNS). In normal adult brain, no macrophages could be detected in the CNS parenchyma; only in the meninges and the choroid plexes were a few macrophages found. During ontogeny, numerous phagocytic cells infiltrated the CNS parenchyma; these cells which did not express Ia are blood-borne. About three weeks after birth, all macrophages had disappeared from the CNS. As microglia in adult and developing brain do not stain with the anti-macrophage antibodies, we suggest that microglial cells are not related to the mononuclear phagocyte system and do not have a hematogenous origin.     

A role for the plasminogen activator system in inflammation and neurodegeneration in the central nervous system during experimental allergic encephalomyelitis

Early signs of inflammatory demyelination include entry of fibrin(ogen) into the central nervous system (CNS), which is normally excluded by the blood-brain barrier, and up-regulation of components of the plasminogen activator system. Using mice deficient in tissue-type plasminogen activator (tPA-/-) and urokinase plasminogen activator receptor (uPAR-/-), we investigated the involvement of the PA system on the clinical and pathological features of experimental allergic encephalomyelitis, an animal model of multiple sclerosis. tPA-/- mice suffered an early and a more severe acute disease characterized by incomplete recovery when compared to wild-type controls, with significantly higher CNS levels of plasminogen activator inhibitor-1. This correlated with fibrin accumulation, which co-localized with nonphosphorylated neurofilament on thickened axons in experimental allergic encephalomyelitis tissue. In contrast, uPAR-/- mice had a delayed, less acute disease reflected in delayed infiltration of inflammatory cells. These animals developed chronic disease as a result of steadily increased inflammation, increased levels of urokinase-type plasminogen activator (uPA), and greater degree of demyelination. Thus, the plasminogen activator system can modulate both inflammatory and degenerative events in the CNS through the respective effects of tPA and uPAR on fibrinolysis and cell adhesion/migration, manipulation of which may have therapeutic implications for multiple sclerosis.     

Immunohistochemical localization of Ca(2+)/calmodulin-dependent protein kinase kinase beta in the rat central nervous system

We examined regional and intracellular distribution of Ca(2+)/calmodulin-dependent protein kinase kinase beta (CaM-KK beta), which activated Ca(2+)/calmodulin-dependent protein kinase I and IV (CaM-K I and IV) immunohistochemically in the central nervous system of the rat by light and electron microscopy. Although most neurons in the brain and spinal cord exhibited the immunoreactivity, no labeled neurons were observed in the globus pallidus or entopeduncular nucleus, and only a small number of neurons showed weak immunoreactivity in the substantia nigra pars reticulata. In general, the immunoreactivity was observed both in the cytoplasm and cellular nucleus, although the immunoreactivity was not found in the cellular nucleus in some large neurons such as in the mesencephalic trigeminal nucleus, lateral vestibular nucleus or gigant cellular reticular formation. As to motoneurons of the cranial nerve nuclei and the anterior horn of the spinal cord, they revealed the immunoreactivity both in the cytoplasm and nucleus. The reaction product appeared as fine granules in the cytoplasm and nucleus under light microscopy. Electron microscopic observations confirmed that the reaction product was localized mainly on the Golgi apparatus or on the nuclear chromatin. Immunolabeling for antibody against CaM-KK beta was discussed with the distribution of CaM-K I, IV and another CaM-KK, CaM-KK alpha, in the central nervous system.     

IgGimmunoreactivities(IgGIR) in the rat central nervous system following administration of the antineurons antibody

以猪脊髓运动神经元（Ｍｎｓ）为抗原免疫Ｂａｌｂ／ｃ小鼠制备抗Ｍｎｓ抗体（ＭｃＡｂ,３６Ｆ６）,该抗体与人和大鼠脊髓Ｍｎｓ有交叉反应。把这些ＩｇＧ抗体注射到肌肉中,ＩｇＧ便经逆行轴浆运输到Ｍｎｓ胞体,而不进入到感觉神经元。用改变的ＡＢＣ方法定位大鼠中枢神经系统的小鼠的ＩｇＧ免疫反应（ＩｇＧ－ＩＲ）。肌肉注射３６Ｆ６后,动物存活４８－７２ｈ,ＭｃＡｂ跨细胞作用可能发生从逆行标记的Ｍｎｓ到Ⅷ、Ⅹ板层（在脊髓水平）,甚至到脑干网状结构的神经元。在同一切片上,网状结构内出现了神经元的跨细胞作用。ＩｇＧ－ＩＲ细胞还可分布在下丘脑室旁核、视上核、新皮质和室管膜细胞以及不规则出现的血管周的胶质细胞和／或神经元。     

Recovery time constant in central nervous system O2 toxicity in the rat

The development of oxygen toxicity can be delayed by intermittent periods of normoxia. However, there is no accepted procedure for quantifing the recovery during normoxia. A cumulative oxygen toxicity index - K, when K reaches a critical value (K _c) and the toxic effect is manifested, can be calculated using the equation K?=?t _e ²?×?PO₂ ^c where t _e is hyperoxic exposure time and PO₂ is oxygen pressure and c is a power parameter. Recovery during normoxia (reducing K) is calculated by the equation K ₂?=?K ₁?×?e^?rtr where t_r is recovery time, r being the recovery time constant. A combination of accumulation of oxygen toxicity and its recovery can be used to calculate central nervous system oxygen toxicity. In protocol A (n?=?25), r was calculated for rats exposed either continuously to 608 kPa oxygen or to PO₂?=?608 kPa followed by a period of normoxia (3.5% O₂), with a subsequent return to PO₂?=?608 kPa until appearance of the first electrical discharge (FED) in the electroencephalogram which precedes clinical convulsions. In protocol B (n?=?22), predicted latency to the FED was compared to measured latency for seven different exposures to hyperbaric oxygen (HBO), followed by a period of normoxia and further HBO exposure. Recovery followed an exponential path, with r?=?0.31 (SD 0.12) min^?1. The predicted latency to FED in protocol B correlated with the measured latencies. Calculation of the recovery of the CNS oxygen toxicity agreed with the previously suggested exponential recovery of the hypoxic ventilatory response and was probably a general recovery process. We concluded that recovery can be applied to the design of various hyperoxic exposures.     

Transgenic expression of CCL2 in the central nervous system prevents experimental autoimmune encephalomyelitis

CC chemokine ligand 2 (CCL2)/monocyte chemotactic protein-1, a member of the CC chemokine family, is a chemoattractant for monocytes and T cells through interaction with its receptor CCR2. In the present study, we examined a T helper cell type 1 (Th1)-dependent disease, proteolipid protein-induced experimental autoimmune encephalomyelitis, in a transgenic mouse line that constitutively expressed low levels of CCL2 in the central nervous system (CNS) under control of the astrocyte-specific glial fibrillary acidic protein promoter. CCL2 transgenic mice developed significantly milder clinical disease than littermate controls. As determined by flow cytometry, mononuclear cell infiltrates in the CNS tissues of CCL2 transgenic and littermate-control mice contained equal numbers of CD4+ and CD8+ T cells, and the CCL2 transgenic mice showed an enhanced number of CNS-infiltrating monocytes. CNS antigen-specific T cells from CCL2 transgenic mice produced markedly less interferon-gamma. Overexpression of CCL2 in the CNS resulted in decreased interleukin-12 receptor expression by antigen-specific T cells. Collectively, these results indicate that sustained, tissue-specific expression of CCL2 in vivo down-regulates the Th1 autoimmune response, culminating in milder clinical disease.     

Tight junctions in brain barriers during central nervous system inflammation

Homeostasis within the central nervous system (CNS) is a prerequisite to elicit proper neuronal function. The CNS is tightly sealed from the changeable milieu of the blood stream by the blood-brain barrier (BBB) and the blood-cerebrospinal fluid (CSF) barrier (BCSFB). Whereas the BBB is established by specialized endothelial cells of CNS microvessels, the BCSFB is formed by the epithelial cells of the choroid plexus. Both constitute physical barriers by a complex network of tight junctions (TJs) between adjacent cells. During many CNS inflammatory disorders, such as multiple sclerosis, human immunodeficiency virus infection, or Alzheimer's disease, production of pro-inflammatory cytokines, matrix metalloproteases, and reactive oxygen species are responsible for alterations of CNS barriers. Barrier dysfunction can contribute to neurological disorders in a passive way by vascular leakage of blood-borne molecules into the CNS and in an active way by guiding the migration of inflammatory cells into the CNS. Both ways may directly be linked to alterations in molecular composition, function, and dynamics of the TJ proteins. This review summarizes current knowledge on the cellular and molecular aspects of the functional and dysfunctional TJ complexes at the BBB and the BCSFB, with a particular emphasis on CNS inflammation and the role of reactive oxygen species.     

Dynorphin-immunoreactive neurons in the central nervous system of the rat

An antiserum specific for the C-terminal region of dynorphin_1–17 (DYN) was used to examine the distribution of this endogenous opioid peptide in the rat brain with the indirect immunofluorescence technique. DYN-positive nerve cell bodies and fibers were found in many nuclei in the spinal cord, medulla, mesencephalon, hypothalamus and forebrain. These findings indicate that a widespread system of DYN neurons is present in the brain distinct from the previously described enkephalin and endorphin systems.     

异丙酚诱导大鼠中枢FOS核蛋白表达的研究

目的　通过检测异丙酚静脉全麻诱导大鼠中枢FOS核蛋白的表达 ,明确静脉全身麻醉的中枢作用位点。方法　 2 1只Wistar大鼠随机分成 3组 :对照组 (C组 )腹腔注入生理盐水 2ml,异丙酚组 (P组 )腹腔注入异丙酚 10 0mg kg ,异丙酚作用后断尾刺激组 (S组 )。 1h后应用FOS蛋白免疫组织化学法 (ABC法 ) ,检测FOS免疫反应 (FOS IR ,immunityreactionofFOS)阳性神经元在大脑的分布。结果　C组可见部分散在FOS IR阳性神经元分布 ,P组FOS IR阳性神经元数比C组明显增多 (P <0 .0 1) ,并呈核特异性分布 ,S组在杏仁基底外侧核、丘脑室旁核、外侧缰核及海马回嗅觉小岛等核团发现FOS IR阳性神经元较P组分布增多 (P <0 .0 1)。结论　异丙酚在大鼠中枢神经系统有与其静脉麻醉作用相关的神经核团。