Search

A monoclonal antibody designated III 5H8 was shown to bind both to astrocytes and to myelin sheaths as studied with immunocytochemical techniques on brain sections and cell cultures. Binding to astrocytes was confirmed by double immunofluorescent labelling of frozen sections and cell cultures with anti-GFAP, and appeared to be sensitive to formalin treatment. Binding to myelin sheaths was confirmed by comparing sections labelled with III 5H8 with sections labelled with antibodies against axons and myelin basic protein as well as by staining of sections of hypomyelinated spinal cord with III 5H8. On immunoblots of separated white matter III 5H8 revealed two bands, while on immunoblots of purified myelin only one band was seen. The findings are discussed with respect to the function of astrocytes in white matter and shared antigenic determinants between astrocytes and oligodendrocytes.

Nitric oxide was first described being produced in inflammatory cells involved in experimental autoimmune encephalomyelitis in 1992. Since then some 45 papers have appeared examining the role of NO in this central nervous system autoimmune inflammatory disease. Of the first 10 papers published all resulted in the interpretation that NO was a pathologic or “bad” molecule in the context of EAE. A few papers then began to appear suggesting that NO may not in fact always be a harmful molecule and by the end of 1997 early 1998, 22 papers suggested a destructive role for the molecule while three suggested it was protective. The past two years have seen a significant increase in reports supporting a protective mechanism for NO in EAE such that as of July 1999, 27 papers suggest a destructive and 15 a protective role for NO with a few uncommitted. This review sets out in a more or less chronological order the studies examining the role of NO in EAE and maps our changing understanding of the molecules role in this CNS inflammatory disease and by inference perhaps multiple sclerosis.

Gut microbiota composition may affect the central nervous system (CNS) and immune function. Several studies have recently examined the possible link between gut microbiota composition and multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Most of these studies agree that patients with MS suffer from dysbiosis. Moreover, an altered proportion of certain phyla of bacteria was detected in the digestive tracts of these patients compared to healthy individuals. This review article gathers information from research papers that have examined the relationship between gut microbiota composition and MS and its possible mechanisms.

Chemokines are small chemotactic molecules widely expressed throughout the central nervous system. A number of papers, during the past few years, have suggested that they have physiological functions in addition to their roles in neuroinflammatory diseases. In this context, the best evidence concerns the CXC-chemokine stromal cell-derived factor (SDF-1α or CXCL12) and its receptor CXCR4, whose signalling cascade is also implicated in the glutamate release process from astrocytes. Recently, astrocytic synaptic like microvesicles (SLMVs) that express vesicular glutamate transporters (VGLUTs) and are able to release glutamate by Ca2+-dependent regulated exocytosis, have been described both in tissue and in cultured astrocytes. Here, in order to elucidate whether SDF-1α/CXCR4 system can participate to the brain fast communication systems, we investigated whether the activation of CXCR4 receptor triggers glutamate exocytosis in astrocytes. By using total internal reflection (TIRF) microscopy and the membrane-fluorescent styryl dye FM4-64, we adapted an imaging methodology recently developed to measure exocytosis and recycling in synaptic terminals, and monitored the CXCR4-mediated exocytosis of SLMVs in astrocytes. We analyzed the co-localization of VGLUT with the FM dye at single-vesicle level, and observed the kinetics of the FM dye release during single fusion events. We found that the activation of CXCR4 receptors triggered a burst of exocytosis on a millisecond time scale that involved the release of Ca2+ from internal stores. These results support the idea that astrocytes can respond to external stimuli and communicate with the neighboring cells via fast release of glutamate.

In 1972 Guido Biozzi selectively bred mice to study the immunopathological mechanisms underlying polygenic diseases. One line, the Biozzi antibody high (AB/H) mouse (now designated the ABH strain) was later found to be highly susceptible to many experimentally induced diseases such as autoimmune encephalomyelitis, autoimmune neuritis, autoimmune uveitis, as well as virus-induced demyelination and has thus been a key mouse strain to study human inflammatory neurological diseases. In this paper we discuss the background of the Biozzi ABH mouse and review how studies with these mice have shed light on the pathogenic mechanisms operating in chronic neurological disease.

Experimental autoimmune encephalomyelitis (EAE) was induced in young (2–3 month old), middle-aged (12–13 month old) and geriatric (24–26 month old) Lewis (JC) rats by active immunisation with myelin basic protein (MBP) in complete Freund's adjuvant (CFA). It was found that aged Lewis (JC) rats developed a more chronic form of EAE than younger rats of the same strain, a phenomenon observed in both male and female rats despite males developing more severe disease than females at all ages. Middle-aged recipients also developed more severe disease than young recipients when EAE was induced by the adoptive transfer of lymphocytes from actively immunised young donors, suggesting that disease chronicity in middle-aged animals is a property of the central nervous system (CNS) milieu. Histological studies demonstrated that disease chronicity did not correlate with the number of inflammatory lesions in the CNS, young animals containing substantial numbers of CNS lesions following recovery and lesions being largely absent from middle-aged animals which still exhibited signs of disease. No significant differences were found in the degree of fibrin deposition or demyelination between young and middle-aged or symptomatic and asymptomatic animals. However, astrocytic hypertrophy was found to correlate with manifestation of disease in both young and middle-aged animals and in particular with disease chronicity in middle-aged animals. In parallel studies, no significant differences were found in the levels of the inflammatory mediators tumor necrosis factor (TNF)-α, prostaglandin E (PGE)2, reactive nitrogen intermediates (RNI) and corticosterone in young and middle-aged animals. However, markedly elevated corticosterone levels were found in both young and middle-aged animals with the development of clinical signs which returned to baseline levels with the resolution of clinical signs. Elevated levels of RNI were evident in animals immediately prior to and during the early stages of symptomatic EAE. Although these results suggest that nitric oxide may play a role in the pathogenesis of disease, whereas corticosterone may play a role in the immunoregulation of the disease, these factors cannot explain differences in disease chronicity evident in middle-aged animals. Based on the results presented in this paper, it is proposed that the neurological deficit of chronic EAE in middle-aged animals may be caused by astrocytic hypertrophy with the resolution of this CNS response being a major factor contributing to recovery from the disease in animals of all ages.

In multiple sclerosis and experimental demyelination, oligodendrocytes and Schwann cells are able to repair myelin lesions of the central nervous system. However, spontaneous myelin repair is often insufficient. Several approaches to enhance remyelination have been considered and transplantation of myelin-forming cells has been proposed as one of them. In this paper, we present results which confirm the ability of transplanted Schwann cells to remyelinate an induced demyelinated lesion of the spinal cord. Schwann cells were either purified Schwann cells isolated from 1-2-day-old rat sciatic nerves, or immortalized Schwann cells (MSC80) arising from a purified culture of 7-day-old mouse sciatic nerves. They were transplanted into or at a distance from a lysolecithin-induced lesion of the Shiverer spinal cord. Labelling of the Schwann cells with the fluorochrome Hoechst 33342 enabled us to trace them after transplantation in their host and evaluate their ability to reach and to repair the demyelinated lesion. Using the Hoechst-Shiverer model, we show that when transplanted in the lesion, cultured Schwann cells, even immortalized, are able to remyelinate such a lesion efficiently. In addition, when transplanted at a distance from the lesion, they are able to reach and repair the lesion in time frames which allow them to compete actively with host oligodendrocytes.

Experimental autoimmune encephalomyelitis (EAE) is an organ-specific autoimmune disease model used to investigate mechanisms involved in the activation of self-reactive T cells. Preproenkephalin (PPNK) is the gene that encodes the protein proenkephalin A that has been detected in the brain, adrenal cells and cells of the immune system. In this paper, whether PPNK plays a role in the development of EAE was investigated. PPNK-deficient and wild-type mice were immunized with the MOG(35-55) peptide and the development of EAE observed. Our results show that PPNK-deficient mice developed less severe clinical signs of disease than wild-type mice, and with lower incidence. MOG(35-55)-specific T cells from PPNK-deficient and wild-type mice produced IFNgamma and TNFalpha but no IL-4 or IL-10, indicative of a Th1 phenotype. However, the numbers of MOG(35-55)-specific IFNgamma-producing cells from immunized PPNK-deficient mice were largely reduced at early stages of disease. Interestingly, there was no difference in clinical signs or infiltrating mononuclear cells in the CNS between wild-type and PPNK-deficient mice at the later stage of disease. Our results suggest that PPNK accelerates the generation of autoimmune IFNgamma-producing T cells and MOG(35-55)-induced EAE.

Peptides with transmitter-like properties have been found in many brain areas. Immunochemical techniques have contributed most to clarification of the function and the pathway of these substances in neuronal systems. In this paper we report the production of 4 monoclonal antibodies against Met-enkephalin and their use in studying this peptide in rat cervical cord. Two of the antibodies recognize the COOH-terminus part of the Met-enkephalin, and do not cross-react with other known peptides. The other two antibodies are mainly directed against the NH 2 -terminus part of the peptide. Specific interactions of these monoclonal antibodies with regions of rat cervical cord were shown by immunochemistry techniques.