Activated human T cells, B cells, and monocytes produce brain-derived neurotrophic factor in vitro and in inflammatory brain lesions: a neuroprotective role of inflammation?
(1/1460)
Brain-derived neurotrophic factor (BDNF) has potent effects on neuronal survival and plasticity during development and after injury. In the nervous system, neurons are considered the major cellular source of BDNF. We demonstrate here that in addition, activated human T cells, B cells, and monocytes secrete bioactive BDNF in vitro. Notably, in T helper (Th)1- and Th2-type CD4(+) T cell lines specific for myelin autoantigens such as myelin basic protein or myelin oligodendrocyte glycoprotein, BDNF production is increased upon antigen stimulation. The BDNF secreted by immune cells is bioactive, as it supports neuronal survival in vitro. Using anti-BDNF monoclonal antibody and polyclonal antiserum, BDNF immunoreactivity is demonstrable in inflammatory infiltrates in the brain of patients with acute disseminated encephalitis and multiple sclerosis. The results raise the possibility that in the nervous system, inflammatory infiltrates have a neuroprotective effect, which may limit the success of nonselective immunotherapies. (+info)
Non-coding plasmid DNA induces IFN-gamma in vivo and suppresses autoimmune encephalomyelitis.
(2/1460)
Regulatory sequences used in plasmids for naked DNA vaccination can modulate cytokine production in vivo. We demonstrate here that injection of plasmid DNA can suppress the prototypic T cell-mediated autoimmune disease, experimental autoimmune encephalomyelitis, by inducing IFN-gamma. (+info)
Transgenic interleukin 10 prevents induction of experimental autoimmune encephalomyelitis.
(3/1460)
The effectiveness of interleukin 10 (IL-10) in the treatment of autoimmune-mediated central nervous system inflammation is controversial. Studies of the model system, experimental autoimmune encephalomyelitis (EAE), using various routes, regimens, and delivery methods of IL-10 suggest that these variables may affect its immunoregulatory function. To study the influence of these factors on IL-10 regulation of EAE pathogenesis, we have analyzed transgenic mice expressing human IL-10 (hIL-10) transgene under the control of a class II major histocompatibility complex (MHC) promoter. The hIL-10 transgenic mice are highly resistant to EAE induced by active immunization, and this resistance appears to be mediated by suppression of autoreactive T cell function. Myelin-reactive T helper 1 cells are induced but nonpathogenic in the IL-10 transgenic mice. Antibody depletion confirmed that EAE resistance is dependent on the presence of the transgenic IL-10. Mice expressing the hIL-10 transgene but not the endogenous murine IL-10 gene demonstrated that transgenic IL-10 from MHC class II-expressing cells is sufficient to block induction of EAE. This study demonstrates that IL-10 can prevent EAE completely if present at appropriate levels and times during disease induction. (+info)
Ups and downs of protein crystallization: studies of protein crystals by high-performance capillary electrophoresis.
(4/1460)
High-performance capillary electrophoresis is a high-technology micro-separation method. Short run time, full automation and minute amounts of sample make it a very attractive technique. In this report we describe studies of protein crystals by capillary electrophoresis. We show how high-performance capillary electrophoresis can be used effectively for rapid evaluation and examination of the protein solution used for crystallization, the protein crystals (solubilized) and surrounding mother liquor. With coated capillaries, the runs were reproducible and disturbing effects, such as electroendosmosis and interaction of the proteins with the capillary wall, were suppressed efficiently. We recommend this new technique as a powerful and routine companion to protein crystallography. (+info)
Analysis of the membrane-interacting domains of myelin basic protein by hydrophobic photolabeling.
(5/1460)
Myelin basic protein is a water soluble membrane protein which interacts with acidic lipids through some type of hydrophobic interaction in addition to electrostatic interactions. Here we show that it can be labeled from within the lipid bilayer when bound to acidic lipids with the hydrophobic photolabel 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine (TID) and by two lipid photolabels. The latter included one with the reactive group near the apolar/polar interface and one with the reactive group linked to an acyl chain to position it deeper in the bilayer. The regions of the protein which interact hydrophobically with lipid to the greatest extent were determined by cleaving the TID-labeled myelin basic protein (MBP) with cathepsin D into peptides 1-43, 44-89, and 90-170. All three peptides from lipid-bound protein were labeled much more than peptides from the protein labeled in solution. However, the peptide labeling pattern was similar for both environments. The two peptides in the N-terminal half were labeled similarly and about twice as much as the C-terminal peptide indicating that the N-terminal half interacts hydrophobically with lipid more than the C-terminal half. MBP can be modified post-translationally in vivo, including by deamidation, which may alter its interactions with lipid. However, deamidation had no effect on the TID labeling of MBP or on the labeling pattern of the cathepsin D peptides. The site of deamidation has been reported to be in the C-terminal half, and its lack of effect on hydrophobic interactions of MBP with lipid are consistent with the conclusion that the N-terminal half interacts hydrophobically more than the C-terminal half. Since other studies of the interaction of isolated N-terminal and C-terminal peptides with lipid also indicate that the N-terminal half interacts hydrophobically with lipid more than the C-terminal half, these results from photolabeling of the intact protein suggest that the N-terminal half of the intact protein interacts with lipid in a similar way as the isolated peptide. The similar behavior of the intact protein to that of its isolated peptides suggests that when the purified protein binds to acidic lipids, it is in a conformation which allows both halves of the protein to interact independently with the lipid bilayer. That is, it does not form a hydrophobic domain made up from different parts of the protein. (+info)
Spontaneous regression of primary autoreactivity during chronic progression of experimental autoimmune encephalomyelitis and multiple sclerosis.
(6/1460)
Experimental autoimmune encephalomyelitis (EAE) is a widely used animal model for multiple sclerosis (MS). EAE is typically initiated by CD4(+) T helper cell type 1 (Th1) autoreactivity directed against a single priming immunodominant myelin peptide determinant. Recent studies have shown that clinical progression of EAE involves the accumulation of neo-autoreactivity, commonly referred to as epitope spreading, directed against peptide determinants not involved in the priming process. This study directly addresses the relative roles of primary autoreactivity and secondary epitope spreading in the progression of both EAE and MS. To this end we serially evaluated the development of several epitope-spreading cascades in SWXJ mice primed with distinctly different encephalitogenic determinants of myelin proteolipid protein. In a series of analogous experiments, we examined the development of epitope spreading in patients with isolated monosymptomatic demyelinating syndrome as their disease progressed to clinically definite MS. Our results indicate that in both EAE and MS, primary proliferative autoreactivity associated with onset of clinical disease invariably regresses with time and is often undetectable during periods of disease progression. In contrast, the emergence of sustained secondary autoreactivity to spreading determinants is consistently associated with disease progression in both EAE and MS. Our results indicate that chronic progression of EAE and MS involves a shifting of autoreactivity from primary initiating self-determinants to defined cascades of secondary determinants that sustain the self-recognition process during disease progression. (+info)
Golli-induced paralysis: a study in anergy and disease.
(7/1460)
The Golli-MBP transcription unit contains three Golli-specific exons as well as the seven exons of the classical myelin basic protein (MBP) gene and encodes alternatively spliced proteins that share amino acid sequence with MBP. Unlike MBP, which is a late Ag expressed only in the nervous system, Golli exon-containing gene products are expressed both pre- and postnatally at many sites, including lymphoid tissue, as well as in the central nervous system. To investigate whether Golli-MBP peptides unique to Golli would result in neurological disease, we immunized rats and observed a novel neurological disease characterized by mild paralysis and the presence of groups of lymphocytes in the subarachnoid space but not in the parenchyma of the brain. Disease was induced by Th1-type T cells that displayed an unusual activation phenotype. Primary stimulation in vitro induced T cell proliferation with increased surface CD45RC that did not become down-regulated as it did in other Ag-stimulated cultures. Secondary stimulation of this CD45RChigh population with Ag, however, did not induce proliferation or IL-2 production, although an IFN-gamma-producing population resulted. Proliferation could be induced by secondary stimulation with IL-2 or PMA-ionomycin, suggesting an anergic T cell population. Cells could adoptively transfer disease after secondary stimulation with IL-2, but not with Ag alone. These responses are suggestive of a chronically stimulated, anergic population that can be transiently activated to cause disease, fall back into an anergic state, and reactivated to cause disease again. Such a scenario may be important in chronic human disease. (+info)
CD28 costimulation is crucial for the development of spontaneous autoimmune encephalomyelitis.
(8/1460)
Multiple sclerosis (MS) is a severe central nervous system disease. Experimental autoimmune encephalomyelitis (EAE) mimics MS in mice. We report that spontaneous development of EAE in RAG-1-deficient mice transgenic for a myelin basic protein (MBP)-specific TCR (TgMBP+/RAG-1-/-) requires expression of the T cell costimulatory molecule CD28. Surprisingly, T cells from CD28-/-TgMBP+/RAG-1-/- mice proliferate and produce IL-2 in response to MBP1-17 peptide in vitro, excluding clonal anergy as the mechanism of CD28-regulated pathogenesis. Proliferation of autoaggressive T cells was dependent on the concentration of the MBP peptide, as was the development of MBP-induced EAE in CD28-deficient PL/J mice. These results provide the first genetic evidence that CD28 costimulation is crucial for MBP-specific T cell activation in vivo and the initiation of spontaneous EAE. (+info)