Search PubMed⌕ Search

Biomedical subjects

C C Bernard

Publications and source records attributed to C C Bernard.

At least 37 records · Page 2Linked to original sources

Molecular detection and quantitation of the chemokine RANTES mRNA in neurological brain.

Accumulation of T-cells in the brains of patients with neurological disorders prompted a molecular analysis of brain tissue for expression of the chemokine RANTES, which is known to be a T-cell activator and chemoattractant. A fast, sensitive and reproducible technique was developed, based on the polymerase chain reaction and nonradioactive detection. The method could detect and quantitate RANTES in small amounts of brain tissue from all patients with multiple sclerosis, and in some patients with other neural or inflammatory diseases. The data indicate constitutive expression of RANTES in brain from some neurological disorders where its downregulation can have therapeutic benefits.

Aged↗

Induction of a multiple sclerosis-like disease in mice with an immunodominant epitope of myelin oligodendrocyte glycoprotein.

Myelin oligodendrocyte glycoprotein (MOG) is postulated to be a target autoantigen in multiple sclerosis (MS). Here we investigated the encephalitogenicity of an immunodominant epitope of MOG, peptide 35-55, in various strains of mice. An MS-like disease was induced in NOD/Lt mice (H-2g7) and C57BL/6 mice (H-2b) by a single injection of MOG35-55 in CFA. The disease followed a relapsing-remitting course in NOD/Lt mice, whereas C57BL/6 mice developed a chronic paralytic disease. Histologically, the disease in both strains was characterized by cellular infiltration and multifocal demyelination in the CNS. Significant DTH type reactions to MOG35-55 were only seen in MOG-susceptible animals, with the NOD/Lt mice showing the strongest responses. Susceptible mice also showed specific antibody responses to MOG35-55 but not to a panel of other MOG peptides. These results provide further evidence for the role of MOG as a highly autoantigenic molecule capable of inducing severe demyelinating disease.

Animals↗

Delayed and incomplete myelination in a transgenic mouse mutant with abnormal oligodendrocytes.

In search of animal models suitable for investigating myelin repair, we have analysed myelinogenesis in a transgenic mouse mutant with delayed myelination, but with a normal life-span. The 2-50 mutant which carries a c-myc gene under the regulation of the myelin basic protein promoter has been described previously (Orian et al.: J Neurosci Res 39:604-612, 1994). Here we show that appropriate mRNA transcripts and their corresponding protein products are generated, but that the accumulation of these products is delayed in transgenic mice with respect to nontransgenic littermates. This phenomenon is associated with aberrant myelin and paucity of normal oligodendrocytes. Myelination appears to be carried out by abnormal, oligodendrocyte-like cells. We propose that the primary defect in the 2-50 mutant is an inability to generate the normal number of mature oligodendrocytes. This mutant represents a novel class of mutant in which oligodendrocyte development and myelination can be studied in the absence of interference with a gene for a structural protein of myelin, in an animal with normal survival. It may also represent a new tool to investigate in vivo gliogenesis and regulatory events bringing about the coordinated regulation of myelin protein synthesis.

Aging↗

A conformational study of the human and rat encephalitogenic myelin oligodendrocyte glycoprotein peptides 35-55.

Myelin oligodendrocyte glycoprotein (MOG), is considered an important central-nervous system-specific target autoantigen for primary demyelination in autoimmune diseases like multiple sclerosis. We have recently demonstrated that MOG or its derived peptide, MOG-(35-55)-peptide, are able to produce in animals, clinicopathologic signs that mimic multiple sclerosis. The rat MOG sequence spanning amino acids 35-55 [rMOG-(35-55)-peptide] differs from the human sequence [hMOG-(35-55)-peptide] by a single amino acid substitution, i.e. Pro42-->Ser. Mice injected with rMOG-(35-55)-peptide showed severe inflammation and demyelination throughout the central nervous system but, interestingly, mice injected with hMOG-(35 -55)-peptide showed only a few foci of mild inflammation with no demyelination. Circular dichroism and nuclear magnetic resonance spectroscopy have been used to structurally characterise the bioactive peptides hMOG-(35-55)-peptide and rMOG-(35-55)-peptide. In 0.1 M K2HPO4/KOH, 90% H2O/D2O solutions, these derived peptides have been shown, by NMR spectroscopy, to adopt detectable levels of short-range structure in equilibrium with unfolded conformers. On addition of 2,2,2-trifluoro-(2H3)ethanol, rMOG-(35-55)-peptide and hMOG-(35-55)-peptide adopt folded structures which have nuclear Overhauser enhancements characteristic of a poorly defined alpha-helix over residues 44-51. There are some indications of secondary structure also evident in the N-terminal region of rMOG-(35-55)-peptide. CD spectroscopy has revealed that in aqueous solution both peptides are unfolded but in 2.2.2-trifluoroethanol and, at micellar concentrations of sodium dodecyl sulfate, rMOG-(35-55)-peptide and, to a lesser extent, hMOG-(35-55)-peptide adopt helical conformations. In contrast, at non-micellar concentrations of SDS rMOG-(35-55)-peptide and hMOG-(35-55)-peptide adopt, according to CD spectroscopy, a beta-structure indicating that the peptides change conformation depending on the microenvironment of the amino acids.

Amino Acid Sequence↗

Myelin oligodendrocyte glycoprotein: a novel candidate autoantigen in multiple sclerosis.

Myelin oligodendrocyte glycoprotein (MOG) is a member of the immunoglobulin superfamily expressed exclusively in central nervous system (CNS) myelin. While the function of MOG is unknown, a number of studies have shown that immune responses to MOG contribute to the autoimmune-mediated demyelination seen in animals immunized with whole CNS tissue. This paper summarizes our recent studies, which unequivocally demonstrate that MOG by itself is able to generate both an encephalitogenic T cell response and an autoantibody response in Lewis rats and in several strains of mice. In Lewis rats the injection of both native MOG and MOG35-55 peptide produces a paralytic relapsing-remitting neurological disease with extensive plaque-like demyelination. The antibody response to MOG35-55 was highly restricted, as no reactivity to either other MOG peptides or myelin proteins could be detected. Fine epitope mapping showed that antibody from serum and cerebrospinal fluid of injected rats reacted strongly to MOG37-46, which is contiguous to the dominant T cell epitope contained within MOG44-55. NOD/Lt and C57BL/6 mice were also susceptible to severe neurological disease following injection with recombinant MOG or MOG35-55 peptide, indicating that this specific CNS autoantigen, or some of its determinants, can induce a pathogenic response across animal species. Severe paralysis and extensive demyelination were seen in both strains, but NOD/Lt mice experienced a chronic relapsing disease whereas C57BL/6 mice had a chronic non-remitting disease. Moreover, transfer of MOG35-55 T cells into naive NOD/Lt mice also produced severe neurological impairment as well as histological lesions. These results emphasize that a synergism between a T cell-response and anti-MOG antibodies may be important for the development of severe demyelinating disease. This, together with our demonstration that there is a predominant T cell response to MOG in patients with multiple sclerosis, clearly indicates that MOG is probably an important target autoantigen in this disease.

Animals↗

Binding of complement component Clq to myelin oligodendrocyte glycoprotein: a novel mechanism for regulating CNS inflammation.

Myelin oligodendrocyte glycoprotein (MOG) is a myelin-specific protein restricted to the central nervous system (CNS). While MOG is considered a putative autoantigen in MS, its function(s) in myelin is unknown. As CNS myelin is able to activate the classical complement pathway, it must contain a Clq-binding/activating protein but the identity of this protein has not been reported. The data in this paper clearly demonstrate that MOG specifically binds Clq in a dose-dependent and saturating manner. This calcium-dependent interaction is mediated by the extracellular immunoglobulin-like domain of MOG. This MOG domain contains an amino acid motif similar to the core Clq-binding sequence previously identified in IgG antibodies. Purified MOG also inhibited the antibody-dependent lysis of RBC by complement. Taken together, these results demonstrate that MOG binds Clq near the IgG binding site and may be the protein responsible for complement activation in myelin. This direct interaction between a myelin-specific protein and Clq has significant implications for CNS inflammation and could be particularly important in demyelinating diseases such as multiple sclerosis.

Animals↗

DNA vaccines for the treatment of autoimmune disease.

DNA vaccines represent one of the most significant developments in vaccine technology in recent years. Although, in general, studies have primarily focused on the induction of protective immune responses against infectious pathogens, the technology may prove useful for other immune-related diseases, including autoimmunity. Autoimmune disease results from a breakdown in tolerance to self antigens; however, the same fundamental immunological reactions that control immune responses to foreign antigens are also likely to operate during the course of autoimmune disease. These include the reciprocal regulation of Th cell subsets. Th1 cells appear to be involved in many organ-specific autoimmune diseases while suppression of disease is associated with cells of the Th2 phenotype. It has been possible, therefore, to suppress many of the pathological consequences of autoimmunity by manipulating the Th1/Th2 cell balance. The induction of Th2 responses by DNA immunization might therefore be expected to have a profound effect on the course of autoimmune disease. Indeed, we have demonstrated that DNA immunization can protect animals against the autoimmune central nervous system inflammatory disease, experimental autoimmune encephalomyelitis (EAE). As many other autoantigens have now been identified, the application of this technology to other autoimmune diseases warrants investigation.

Animals↗

Perivascular T cells express the pro-inflammatory chemokine RANTES mRNA in multiple sclerosis lesions.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS), characterized by accumulation of mononuclear cells. The pathogenesis of MS is complex and probably involves soluble immune mediators, particularly cytokines, and activated memory T cells, that are thought to migrate into the CNS. During lesion formation in MS, cytokines regulate cell functions, such as cell recruitment and migration. Because the chemokine RANTES play a role in both activating and recruiting leucocytes, particularly memory T cells into inflammatory sites, the authors have assessed RANTES mRNA levels at the site of lesions. Expression levels were analysed in brain samples and compared with neurological, infectious and other controls. RANTES was expressed by activated perivascular memory T cells, predominantly located at the edge of active plaques. While RANTES mRNA was detected in all 17 MS brains analysed, it was only found in six of the 14 control patients and generally at a lower expression level. In view of the regulatory and chemotactic properties of RANTES, these results imply that RANTES in MS lesions may play an important role in the activation and/or selective accumulation of memory T cells and, thereby, in the pathogenic events associated with MS.

Adult↗

Demyelinating antibodies to myelin oligodendrocyte glycoprotein and galactocerebroside induce degradation of myelin basic protein in isolated human myelin.

Although the specificity of multiple sclerosis (MS) brain immunoglobulins (Igs) remains unknown, the incubation of these Igs with human myelin can lead to myelin basic protein (MBP) degradation mediated by neutral proteases. In this study, we demonstrate that monoclonal antibodies (mAbs) specific to myelin components such as the CNS-specific myelin oligodendrocyte glycoprotein (MOG) and galactocerebroside (GalC) are found to induce a significant loss of MBP mediated by neutral proteases in myelin. By contrast, antibodies to periaxonal and structural components of myelin, such as MBP and myelin-associated glycoprotein, are ineffective in inducing such MBP degradation. Among the 11 different anti-MOG mAbs directed to externally located epitopes of MOG, only two were found to induce a significant degradation of MBP, suggesting that antibody-induced MBP degradation is not only antigen specific but also epitope specific. Based on the inhibition of MBP degradation in the presence of EGTA and the analysis of the degradation products obtained following incubation of myelin with mAbs to GalC and MOG (8-18C5), the neutral protease involved in this antibody-induced degradation of MBP could be calcium-activated neutral protease. Taken together, these results suggest that antibodies to GalC and MOG can play a major role in destabilizing myelin through MBP breakdown mediated by neutral proteases and thus have an important role to play in the pathogenesis of MS.

Antigens, Surface↗

Regulation of myelin oligodendrocyte glycoprotein in different species throughout development.

The assembly and function of central nervous system (CNS) myelin requires the coordinated expression of several myelin-specific proteins, including myelin oligodendrocyte glycoprotein (MOG). Despite the recent cloning of MOG, the function of this molecule is still unknown. Because MOG is a late marker of oligodendrocyte maturation and is exclusively expressed in the CNS on the outermost lamellae of the myelin membrane, it is possible that this molecule plays an important role in the control and maintenance of myelination. Furthermore, as a member of the immunoglobulin superfamily that carries the L2/HNK-1 epitope, it has also been suggested that MOG is involved in cell-cell interaction, perhaps functioning as an adhesive molecule for bundles of nerve fibres. In order to further delineate the role of MOG throughout development we have analysed, by immunoblotting, the developmental appearance and accumulation pattern of MOG in the CNS of three mammalian species. We have also purified MOG to homogeneity from five different species including rat, guinea pig, bovine, monkey and human. Immunoblotting revealed two major MOG bands at 28 and 55 kD in all species. The 55 kD band appears to be a dimer of the lower band although treatment with 2-mercaptoethanol or EDTA failed to abolish it. Purified MOG from all species also displayed faint reactivity with bands at 36, 48 and 78 kD. While the 78 kD band may represent a trimer of MOG, the identity of the other bands remains unknown. Developmental studies in mouse, rat, guinea pig and bovine showed at as for other myelin proteins, MOG displayed a caudorostral gradient of expression, appearing in the spinal cord before the brain. The sensitivity of the detection system used here allowed us to detect MOG protein earlier than in previous reports such that its presence was clearly demonstrated in the CNS of mice and rats at 14 and 10 days after birth, respectively. Analysis of MOG expression in a novel transgenic mouse model that has both delayed and reduced myelination revealed that, like other myelin proteins, MOG expression was delayed compared with normal littermates. These results demonstrate that the expression of MOG is similar in all species and is regulated in a manner consistent with other myelin-specific proteins.

Aging↗

The effect of HLA-DRB1 disease susceptibility markers on the expression of RA.

The study was designed to examine the effect on clinical expression of rheumatoid arthritis (RA) of HLA alleles, particularly DR4 and DR1 that contain susceptibility sequences for RA in the third hypervariable region (HVR3) of HLA-DRB1. We studied 114 consecutive Australian patients with RA attending a hospital outpatient clinic. The effects on indices of disease severity and activity of HLA DR4 and DR1, the DRB1*04 subtypes, and the polymorphism in the RA susceptibility sequence (QRRAA or QKRAA) were examined. The patients were initially divided into 6 groups, DR4,4; DR4,1; DR1,1; DR4/X; DR1,X, and DRX/X, and then further subdivided according to the actual HVR3 susceptibility sequence. The high risk conferred by the HVR3 susceptibility sequence, present in 76%, was confirmed, but 24% of the patients with long-standing seropositive erosive RA lacked this sequence. Among these those with DR2 had early-onset severe disease, and those with DR3 had late-onset milder disease. Differences in expression correlated with polymorphisms in the susceptibility sequence, in that active RA was associated more with QRRAA than QKRAA. There was no correlation of any HLA allele with disease severity. Our finding that the presence of the HVR3 sequence confers susceptibility and also influences the clinical expression and tempo of progression of RA suggests a role in pathogenesis for antigen presentation, whether of an autoantigenic molecule or a persisting infection.

Adult↗

IFN-gamma plays a critical down-regulatory role in the induction and effector phase of myelin oligodendrocyte glycoprotein-induced autoimmune encephalomyelitis.

129/Sv mice are resistant to induction of experimental autoimmune encephalomyelitis (EAE) induced with myelin oligodendrocyte glycoprotein peptide (MOG35-55). Mice of this strain lacking the gene coding for the ligand-binding chain of the IFN-gamma receptor develop EAE with high morbidity and mortality. Spleen cells from sensitized IFN-gammaR-/- mice proliferated extensively when stimulated with MOG peptide in culture and produced high levels of IFN-gamma and TNF but no detectable IL-4. Transfer of spleen cells from sensitized IFN-gammaR-/- mice produced EAE in both IFN-gammaR+/+ and IFN-gammaR-/- recipients. Disease was severe in IFN-gammaR-/- recipients and mortality high (77%). Surviving mice remained moribund until termination of the experiments. IFN-gammaR+/+ recipients developed disease of equal severity, but with no mortality, and recovered significantly. These results indicate that IFN-gamma is not essential for the generation or function of anti-MOG35-55 effector cells but does play an important role in down-regulating EAE at both the effector and induction phase of disease.

Amino Acid Sequence↗

Analysis of the fine B cell specificity during the chronic/relapsing course of a multiple sclerosis-like disease in Lewis rats injected with the encephalitogenic myelin oligodendrocyte glycoprotein peptide 35-55.

We have recently shown that a single injection of myelin oligodendrocyte glycoprotein (MOG), or the MOG35-55 peptide, produces a relapsing-remitting neurologic disease with extensive plaque-like demyelination. Given the features that this new autoimmune demyelinating model has in common with the clinicopathologic manifestations of multiple sclerosis, we have examined the Ab reactivity to native MOG and MOG35-55 peptide during the course of the disease in Lewis rats. Following immunization with MOG35-55, varied clinical symptoms were observed; these included hind and foreleg paralysis and various degrees of balance impairment. Disease progression also varied: 3 out of 21 animals had a single mild disease episode; 4 out of 21 had a mild relapsing-remitting disease; and 14 out of 21 had severe relapsing-remitting disease. Ab reactivity to MOG35-55 and native MOG was first detected in all rats 4 wk postimmunization and persisted throughout the 12 wk of observation. The Ab response was highly restricted with no reactivity to other peptides encompassing different extracellular segments of MOG. Fine epitope mapping showed that Ab from serum and cerebrospinal fluid of injected rats reacted strongly to MOG37-46 and to a lesser extent to MOG43-50. Although significant levels of anti-MOG Abs appeared necessary for the development of demyelinating lesions, their presence in blood and cerebrospinal fluid alone was not sufficient to produce severe clinical symptoms. These results demonstrate that the MOG35-55 peptide is highly encephalitogenic and can induce strong T and B cell responses. It is probably the complex interaction between these T and B cells that determines the severity of disease in individual rats.

Amino Acid Sequence↗

Immunosusceptibility genes in rheumatoid arthritis.

The polygenic predisposition to RA is conferred particularly by disease susceptibility sequences in the HVR3 of HLA DRB1 present in those subtypes of DR4 and DR1 that are associated with RA. The aim of this study was to examine predisposing interactions between genes encoding HLA and immunoglobulin molecules. Accordingly, we compared the genetic background of 114 Australian patients with RA with that of Australian controls of similar ethnic background. We identified HLA-A, B, and DR phenotypes serologically, HLA-DR, DQ alleles, and subtypes of DR4 by DNA typing, and Gm allogenotypes and immunoglobulin switch region polymorphisms by RFLP. For the subjects with RA, we confirmed previously reported observations that included an excess of females, 71%, a high frequency of HLA types DR4 or DR1 of 77% versus controls 47%, and a high frequency of the HVR3 susceptibility sequences of 76%, with 24% homozygous, and 52% heterozygous for the sequences. We observed other genetic correlations in RA that included increases in frequencies of DR4 in males, DR1 in females, the class I specificity HLA-B27 overall but more particularly in females, 24% in females, versus 5% of controls, HLA-DQB1*0302 (DQ8) in DR4*0401-positive patients, and the Gm allogenotype 1,2,3;23 +/- ; 5,10, 15% of patients versus 4% of controls. Examination of switch region genes gave no evidence of differences in the polymorphisms distributions. Thus, the major genetic risks for RA that are conferred by female gender and the HVR3 of HLA DRB1 are modulated by interactions between gender and HLA class I and class II alleles, and the Gm allogenotype.

Adult↗

Antibody response in Lewis rats injected with myelin oligodendrocyte glycoprotein derived peptides.

Previous studies from our laboratory have demonstrated a predominant response to myelin oligodendrocyte glycoprotein (MOG) in patients with multiple sclerosis (MS) and showed that this molecule is able to induce in Lewis rats a chronic relapsing MS-like disease with extensive demyelination. To further study the possibility that MOG is a primary target antigen in MS, we have begun to investigate the encephalitogenicity and antibody response of different sequences of the extracellular domains of MOG in Lewis rats. We report that none of the synthetic peptides encompassing the MOG amino acid sequences 1-21, 67-87, 104-117 and 202-218 were encephalitogenic. In contrast, a single injection of MOG35-55 was able to induce severe neurological signs associated with inflammation and demyelination. All rats injected with MOG peptides 1-21, 35-55, 67-87 and 202-218 developed a high level of antibodies to their respective immunizing peptides as detected by ELISA and immunoblotting. Although all MOG peptide antisera reacted with immunoblots of native MOG separated under reducing conditions, only anti-MOG35-55 and anti-MOG202-218 antibodies reacted to native MOG, when tested under nonreducing conditions. These results indicate that the MOG35-55 peptide, which is found in the extracellular Ig V-like domain of MOG, is not only an encephalitogenic epitope but could also be an important determinant for initiating antibody-mediated demyelination. As indicated by the absence of reactivity to the other MOG peptides tested, as well as other central nervous system myelin proteins including myelin basic protein and proteolipid protein, the antibody response produced by MOG peptides is highly restricted.

Amino Acid Sequence↗

Changes of extracellular space volume and tortuosity in the spinal cord of Lewis rats with experimental autoimmune encephalomyelitis.

Three diffusion parameters of nervous tissue, extracellular space (ECS) volume fraction (alpha), tortuosity (gamma) and non-specific uptake (k') of tetramethylammonium (TMA+), were studied in the spinal cord of rats during experimental autoimmune encephalomyelitis (EAE). The three parameters were determined in vivo from concentration-time profiles of TMA+ using ion-selective microelectrodes. EAE was induced by injection of guinea-pig myelin basic protein (MBP), which resulted in typical morphological changes in the CNS tissue, namely inflammatory reaction, astrogliosis, blood-brain barrier (BBB) damage and paralysis. EAE was accompanied by a statistically significant increase of alpha (mean +/- S.E.M.) in the dorsal horn from 0.21 +/- 0.01 to 0.28 +/- 0.02, in the intermediate region from 0.22 +/- 0.01 to 0.33 +/- 0.02, in the ventral horn from 0.23 +/- 0.01 to 0.47 +/- 0.02 and in white matter from 0.18 +/- 0.03 to 0.30 +/- 0.03. There were significant decreases in tortuosity in the dorsal horn and in the intermediate region and decreases in non-specific uptake in the intermediate region and in the ventral horn. Although the inflammatory reaction and the astrogliosis preceded and greatly outlasted the neurological symptoms, the BBB damage had a similar time course. Moreover, there was a close correlation between the changes in extracellular space diffusion parameters and the manifestation of neurological signs. We suggest that the expansion of the extracellular space alters the diffusion properties in the spinal cord. This may affect synaptic as well as non-synaptic transmission, intercellular communication and recovery from acute EAE, and may contribute to the manifestation of neurological signs in EAE rats.

Animals↗

Myelin oligodendrocyte glycoprotein induces a demyelinating encephalomyelitis resembling multiple sclerosis.

Chronic relapsing experimental autoimmune encephalomyelitis, a demyelinating disease induced by injection of central nervous system (CNS) tissue, is widely used as a model for multiple sclerosis. However, it is unclear which Ag or combination of Ags in the CNS induce the demyelinating immune response. We now show in Lewis rats that a single injection of myelin oligodendrocyte glycoprotein, a specific CNS myelin component, or an appropriately derived myelin oligodendrocyte glycoprotein peptide produces a relapsing remitting neurologic disease with extensive plaque-like demyelination. Igs from affected animals reacted specifically with myelin oligodendrocyte glycoprotein and stimulated a myelin protease activity, leading to myelin basic protein degradation. The demonstrated involvement of myelin oligodendrocyte glycoprotein as a new demyelinating neural Ag may provide a deeper insight into the pathogenesis of multiple sclerosis and its treatment.

Amino Acid Sequence↗

Characterization of cDNA and genomic clones encoding human myelin oligodendrocyte glycoprotein.

Myelin oligodendrocyte glycoprotein (MOG) is a transmembrane protein expressed only in the CNS and is a possible target autoantigen in multiple sclerosis (MS). To further study the association of MOG with MS, we have characterized cDNA and genomic clones encoding human MOG. The human MOG cDNA, like its rodent and bovine counterparts, encodes a mature protein containing an Ig-like domain, followed by two potential membrane-spanning regions. The intron-exon boundaries of the human MOG gene were mapped and revealed that the signal peptide is encoded by the first exon, the Ig-like domain of MOG is encoded on the second exon, whereas the remainder of the molecule is encoded by six shorter exons. In addition to the major cDNA species, a second class of MOG cDNA was isolated in which an intron was retained. Not only did this second cDNA species represent 30% of the clones analyzed (nine of 30), but RNA encoding this form was detectable by northern and reverse transcription-polymerase chain reaction analysis of the brain and spinal cord. Furthermore, we describe several restriction fragment length polymorphisms of the human MOG gene, one of which may be associated with MS susceptibility.

Amino Acid Sequence↗