Biomedical subjects

J M Greer

Publications and source records attributed to J M Greer.

At least 19 recordsLinked to original sources

PubMed2005

The presence of glutamic acid at positions 71 or 74 in pocket 4 of the HLA-DRbeta1 chain is associated with the clinical course of multiple sclerosis.

BACKGROUND: Primary progressive multiple sclerosis (PP-MS) differs from relapsing-remitting or secondary progressive MS (RR/SP-MS) in ways suggesting differences in the pathogenic pathways. Susceptibility to both PP-MS and RR/SP-MS is linked to carriage of the HLA molecule DRB1*1501. Several serologically defined HLA-DR groups (DR1, DR4, DR6, and DR9) occur less often in RR/SP-MS than in controls. Some or all of the HLA-DR molecules encoded by alleles in these serologically defined groups have a negatively charged glutamic acid at residue 71 or 74 of the beta1 chain (beta1(71)/beta1(74)). Residues at these positions are important in the formation of pocket 4 in the antigen binding site of the HLA-DR molecule. OBJECTIVES: To investigate whether the presence of alleles encoding HLA-DR molecules containing glutamic acid at beta1(71)/beta1(74) correlates with the course of MS. METHODS: HLA-DR and HLA-DQ alleles and genotypes were analysed in 121 MS patients (50 with PP-MS) and 109 controls by molecular typing. RESULTS: Alleles encoding HLA-DR molecules containing a glutamic acid at beta1(71)/beta1(74) occurred less often in patients with RR/SP-MS than in those with PP-MS or controls. In subjects not carrying the DRB1*1501 allele, a much higher proportion of PP-MS patients carried alleles encoding HLA-DR molecules containing a glutamic acid at beta1(71)/beta1(74) than did RR/SP-MS patients or controls. CONCLUSIONS: The amino acid residues involved in determining the shape and charge of pocket 4 of the HLA-DR beta1 chain could influence the clinical course of MS by determining protection against RR/SP-MS or susceptibility to the development of PP-MS.

Alleles↗

PubMed2001

Thiopalmitoylation of myelin proteolipid protein epitopes enhances immunogenicity and encephalitogenicity.

Proteolipid protein (PLP) is the most abundant protein of CNS myelin, and is posttranslationally acylated by covalent attachment of long chain fatty acids to cysteine residues via a thioester linkage. Two of the acylation sites are within epitopes of PLP that are encephalitogenic in SJL/J mice (PLP(104-117) and PLP(139-151)) and against which increased immune responses have been detected in some multiple sclerosis patients. It is known that attachment of certain types of lipid side chains to peptides can result in their enhanced immunogenicity. The aim of this study was to determine whether thioacylated PLP peptides, as occur in the native protein, are more immunogenic than their nonacylated counterparts, and whether thioacylation influences the development of autoreactivity and experimental autoimmune encephalomyelitis. The results show that in comparison with nonacylated peptides, thioacylated PLP lipopeptides can induce greater T cell and Ab responses to both the acylated and nonacylated peptides. They also enhanced the development and chronicity of experimental autoimmune encephalomyelitis. Synthetic peptides in which the fatty acid was attached via an amide linkage at the N terminus were not encephalitogenic, and they induced greater proportions of CD8+ cells in initial in vitro stimulation. Therefore, the lability and the site of the linkage between the peptide and fatty acid may be important for induction of encephalitogenic CD4+ T cells. These results suggest that immune responses induced by endogenous thioacylated lipopeptides may contribute to the immunopathogenesis of chronic experimental demyelinating diseases and multiple sclerosis.

Acylation↗

PubMed2000

Early pregnancy factor suppresses experimental autoimmune encephalomyelitis induced in Lewis rats with myelin basic protein and in SJL/J mice with myelin proteolipid protein peptide 139-151.

Early pregnancy factor (EPF) is a secreted protein with immunosuppressive and growth factor properties. During pregnancy, it appears in maternal serum within 6-24 h of fertilization, is present for at least the first two-thirds of pregnancy in all species studied and is essential for embryonic survival. It is a homologue of chaperonin 10, a heat shock protein, but, unlike other members of this family, EPF has an extracellular role. As it has the ability to modulate CD4+ T cell-dependent immune responses, its role in treatment of experimental autoimmune encephalomyelitis (EAE) was investigated. EAE is a CD4+ T cell-mediated disease, the best available animal model of multiple sclerosis (MS). Two models of EAE were investigated, acute EAE induced in Lewis rats by inoculation with myelin basic protein (MBP-EAE) and chronic relapsing EAE induced in SJL/J mice by inoculation with myelin proteolipid protein peptide (residues 139-151) (PLP-EAE). EPF, delivered intraperitoneally or orally to rats or intraperitoneally to mice, suppressed clinical signs of disease. Mice with PLP-EAE were also treated with interferon-beta, with and without EPF. Both EPF and IFN-beta suppressed clinical signs of EAE and, when administered together, gave greater suppression than when given separately. These findings suggest that EPF may be a potential candidate for use in treatment of MS and may be of use in combined therapy with IFN-beta.

Adjuvants, Immunologic↗

PubMed2000

Surges of increased T cell reactivity to an encephalitogenic region of myelin proteolipid protein occur more often in patients with multiple sclerosis than in healthy subjects.

We have previously shown that patients with multiple sclerosis (MS) have increased T cell responses to the immunodominant region (residues 184-209) of myelin proteolipid protein (PLP). The present study investigated whether this reactivity fluctuates over time and correlates with disease activity. We performed monthly limiting dilution assays for 12-16 mo in four healthy subjects and five patients with relapsing-remitting MS to quantify the frequencies of circulating T cells proliferating in response to PLP(41-58), PLP(184-199), PLP(190-209), myelin basic protein (MBP), MBP(82-100), and tetanus toxoid. Disease activity was monitored by clinical assessment and gadolinium-enhanced magnetic resonance imaging of the brain. There were fluctuations in the frequencies of autoreactive T cells in all subjects. Compared with healthy controls, MS patients had significantly more frequent surges of T cells reactive to the 184-209 region of PLP, but infrequent surges of T cell reactivity to MBP(82-100). There was temporal clustering of the surges of T cell reactivity to MBP(82-100) and MBP, suggesting T cell activation by environmental stimuli. Some clinical relapses were preceded by surges of T cell reactivity to PLP(184-209), and in one patient there was significant correlation between the frequency of T cells reactive to PLP(184-199) and the total number of gadolinium-enhancing magnetic resonance imaging lesions. However, other relapses were not associated with surges of T cell reactivity to the Ags tested. T cells reactive to PLP(184-209) may contribute to the development of some of the CNS lesions in MS.

Adult↗

PubMed2000

Maintenance of functional equivalence during paralogous Hox gene evolution.

Biological diversity is driven mainly by gene duplication followed by mutation and selection. This divergence in either regulatory or protein-coding sequences can result in quite different biological functions for even closely related genes. This concept is exemplified by the mammalian Hox gene complex, a group of 39 genes which are located on 4 linkage groups, dispersed on 4 chromosomes. The evolution of this complex began with amplification in cis of a primordial Hox gene to produce 13 members, followed by duplications in trans of much of the entire unit. As a consequence, Hox genes that occupy the same relative position along the 5' to 3' chromosomal coordinate (trans-paralogous genes) share more similarity in sequence and expression pattern than do adjacent Hox genes on the same chromosome. Studies in mice indicate that although individual family members may have unique biological roles, they also share overlapping functions with their paralogues. Here we show that the proteins encoded by the paralogous genes, Hoxa3 and Hoxd3, can carry out identical biological functions, and that the different roles attributed to these genes are the result of quantitative modulations in gene expression.

Alleles↗

PubMed2000

A neuropathological analysis of experimental autoimmune encephalomyelitis with predominant brain stem and cerebellar involvement and differences between active and passive induction.

Experimental autoimmune encephalomyelitis (EAE) is an autoimmune demyelinating disease that can be induced in a variety of animal species and which is commonly used as an animal model of multiple sclerosis. In rodent EAE models, the clinical disease is typified by ascending paralysis; however, other clinical patterns can also be observed by inducing disease with particular peptides of myelin proteolipid protein (PLP) or myelin oligodendrocyte glycoprotein. Here we describe EAE induced in C3H/HeJ mice by inoculation with residues 190-209 of PLP. This form of EAE is manifested clinically by a movement disorder, with axial rotation of the head and trunk. Histologically, this form of EAE is characterized by predominant cerebellar or brain stem involvement, depending on whether EAE is induced by active immunization with the PLP peptide, or by passive transfer of T cells specific for the peptide. The inflammatory cell infiltrate is composed of polymorphonuclear cells and mononuclear cells. This rotatory form of EAE may be a useful model for studying the neuropathological characteristics of multiple sclerosis affecting the brain stem and cerebellum.

Animals↗

PubMed1999

Targeting genes for self-excision in the germ line.

A procedure is described that directs the self-induced deletion of DNA sequences as they pass through the male germ line of mice. The testes-specific promoter from the angiotensin-converting enzyme gene was used to drive expression of the Cre-recombinase gene. Cre was linked to the selectable marker Neor, and the two genes flanked with loxP elements. This cassette was targeted to the Hoxa3 gene in mouse ES cells that were in turn used to generate chimeric mice. In these chimeras, somatic cells derived from the ES cells retained the cassette, but self-excision occurred in all ES-cell-derived sperm.

Animals↗

PubMed1998

Increased circulating antiganglioside antibodies in primary and secondary progressive multiple sclerosis.

Plasma samples from 70 patients with multiple sclerosis (MS), 41 patients with other neurological diseases (OND), and 38 healthy subjects were examined for antibodies against gangliosides GM1, GM3, GD1a, GD1b, and GD3 using enzyme-linked immunosorbent assays. The percentages of subjects with increased anti-GM3 responses were significantly higher in the primary progressive MS (56.3%) and secondary progressive MS (42.9%) groups than in the relapsing-remitting MS (2.9%), healthy subject (2.6%), and OND (14.6%) groups. Elevated antiganglioside antibodies may be secondary to axonal damage or may be a cause of axonal damage and accumulating disability in progressive MS. In either case, they may serve as a marker of axonal damage in MS.

Antibodies↗

PubMed1997

Autopathogenic T helper cell type 1 (Th1) and protective Th2 clones differ in their recognition of the autoantigenic peptide of myelin proteolipid protein.

We previously generated a panel of T helper cell 1 (Th1) clones specific for an encephalitogenic peptide of myelin proteolipid protein (PLP) peptide 139-151 (HSLGKWLGHPDKF) that induces experimental autoimmune encephalomyelitis (EAE) upon adoptive transfer. In spite of the differences in their T cell receptor (TCR) gene usage, all these Th1 clones required W144 as the primary and most critical TCR contact residue for the activation. In this study, we determined the TCR contact residues of a panel of Th2/Th0 clones specific for the PLP peptide 139-151 generated either by immunization with the PLP 139-151 peptide with anti- B7-1 antibody or by immunization with an altered peptide Q144. Using alanine-substituted peptide analogues of the native PLP peptide, we show that the Th2 clones have shifted their primary contact residue to the NH2-terminal end of the peptide. These Th2 cells do not show any dependence on the W144, but show a critical requirement for L141/G142 as their major TCR contact residue. Thus, in contrast with the Th1 clones that did not proliferate to A144-substituted peptide, the Th2 clones tolerated a substitution at position 144 and proliferated to A144 peptide. This alternative A144 reactive repertoire appears to have a critical role in the regulation of autoimmune response to PLP 139-151 because preimmunization with A144 to expand the L141/G142-reactive repertoire protects mice from developing EAE induced with the native PLP 139-151 peptide. These data suggest that a balance between two different T cell repertoires specific for same autoantigenic epitope can determine disease phenotype, i.e., resistance or susceptibility to an autoimmune disease.

Adoptive Transfer↗

PubMed1997

Encephalitogenicity of murine, but not bovine, DM20 in SJL mice is due to a single amino acid difference in the immunodominant encephalitogenic epitope.

Myelin proteolipid protein (PLP) contains 2 immunodominant encephalitogenic epitopes in SJL mice, namely PLP residues 139-151 and 178-191. DM20, a minor isoform of PLP, lacks residues 116-150 and consequently contains only the single major encephalitogenic epitope 178-191. However, it has been found previously that bovine DM20 is not encephalitogenic in SJL mice. Since residue 188 within peptide 178-191 is phenylalanine (F) in murine DM20 and alanine (A) in bovine DM20, we tested the effect of this difference on the immune responses and induction of EAE. SJL mice were immunized with either highly purified murine or bovine DM20. Residues 178-191 were found to be immunodominant for each, but only murine and not bovine DM20 was encephalitogenic. A synthetic peptide corresponding to the murine 178-191 sequence (F188) was also encephalitogenic, whereas the peptide corresponding to the bovine sequence (A188) was not. Both F188 and A188 bind with high affinity to I-As and both are recognized by the SJL T cell repertoire. A188-specific T cell lines reacted to both A188 and F188, but F188-specific T cell lines were not stimulated by A188. F188-specific T cell lines produced mRNA for the Th1 cytokines IL2 and IFN gamma and, in passive transfer experiments, were encephalitogenic upon stimulation with F188, but not A188. In contrast, A188-specific T cell lines produced mRNA for IL4, IL5 and Il10, in addition to IL2 and IFN gamma, and were not encephalitogenic after stimulation with either F188 or A188. Cotransfer of A188-specific T cell lines with F188-specific T cell lines resulted in protection from EAE. Thus, A188 induces a functionally different phenotype of T cells from that induced by F188. Taken together these data suggest that the failure of bovine DM20 to induce EAE may be attributable to induction of protective rather than pathogenic T cell by the immunodominant epitope.

Amino Acid Sequence↗

PubMed1997

Increased immunoreactivity to two overlapping peptides of myelin proteolipid protein in multiple sclerosis.

We tested the proliferative responses of peripheral blood mononuclear cells from 61 patients with multiple sclerosis, 56 healthy control subjects and 52 patients with other neurological diseases to seven synthetic peptides of myelin proteolipid protein (PLP) and 19 synthetic peptides of myelin basic protein (MBP). Increased proliferative responses to two overlapping PLP peptides, PLP184-199 and PLP190-209 were found significantly more frequently in blood from patients with relapsing-remitting or secondary progressive multiple sclerosis (52.3%), but not from those with primary progressive multiple sclerosis (18.2%), than in that from healthy control subjects (8.9%) and patients with other neurological diseases (20.8%). Reactivity to these PLP peptides was most frequently seen in blood from patients with multiple sclerosis of 6-15 years duration and with moderate to severe disability (Kurtzke's Expanded Disability Status Scale > 4.0); the blood from 15 of 19 patients in this group reacted to one or both of the peptides. Both peptides could be recognized by short-term T-cell lines specific for whole PLP, and lines specific for one or other of the two overlapping peptides were able to recognize whole PLP, indicating that these peptides can be processed naturally from the intact molecule. This region of PLP is encephalitogenic in a number of strains of mice. Samples from multiple sclerosis patients did not react more frequently to any of the MBP peptides than those from healthy control subjects. The proportions of patients with other neurological diseases whose blood responded to the MBP peptides that most frequently elicited responses in blood from multiple sclerosis patients were significantly lower than the proportions of multiple sclerosis patients and healthy control subjects whose blood responded to these peptides.

Adolescent↗

PubMed1996

Genetic analysis of susceptibility to experimental autoimmune encephalomyelitis in a cross between SJL/J and B10.S mice.

Experimental autoimmune encephalomyelitis (EAE), a model for human multiple sclerosis, is a T cell-mediated autoimmune disease that can be induced in experimental animals by immunization with myelin Ags. Inbred strains of mice show varying degrees of susceptibility to EAE, indicating that susceptibility is an inherited trait. To define the genetic factors that control susceptibility to EAE, we performed linkage analysis on the first backcross (BC1) between highly susceptible SJL/J mice and resistant B10.S mice, both of which are of the H-2s haplotype. Mice were immunized for disease with encephalitogenic myelin proteolipid protein peptide 139 to 151, and analysis was performed on 68 backcross mice showing the severe disease phenotype (disease score > or = 3)and 68 backcross mice of the resistant phenotype (no clinical or histologic signs of disease) using microsatellite markers covering >98% of the genome. We found the strongest linkage (p = 0.001) with clinical disease at two loci: one at the telomeric end of chromosome 2, and another near the center of chromosome 3. In addition, several other regions showing some evidence of linkage (p < or = 0.05) with clinical disease were found.

Animals↗

PubMed1996

Immunogenic and encephalitogenic epitope clusters of myelin proteolipid protein.

To understand and develop strategies to intervene in autoimmune responses to myelin proteolipid protein (PLP), encephalitogenic epitopes must be identified. To expedite the identification of potentially immunogenic and encephalitogenic epitopes of PLP, overlapping synthetic 20-mer PLP peptides covering the whole PLP molecule were screened for their ability to bind to purified mouse I-Ad, I-Ak, and I-As molecules. The peptides that bound to the I-A molecules were tested for their ability to induce immune responses in corresponding inbred mouse strains. Immunogenic peptides were then tested for their ability to induce experimental autoimmune encephalomyelitis. Moderate to strong I-A binding was essential for development of immune responses, but immunogenicity was not sufficient for encephalitogenicity. Rather, encephalitogenic epitopes clustered in three regions of the molecule, namely within residues 40-70, 100-119, and 178-209. These were also the regions of the PLP that showed the greatest promiscuity in binding to I-A molecules. Except for PLP 139-151, which is an encephalitogenic determinant in mice expressing I-As, all encephalitogenic epitopes of PLP previously identified, regardless of their MHC class II restriction, are located within or adjacent to these epitope clusters. None of the encephalitogenic epitopes occur in regions of the molecule that have a high degree of homology with the neuronal M6a protein, a member of the DM20/PLP superfamily. Atypical clinical and histologic patterns of experimental autoimmune encephalomyelitis were observed in some strains of mice sensitized with certain PLP peptides and may reflect induction of T cells with different disease-inducing potentials.

Amino Acid Sequence↗

PubMed1996

Orientation of myelin proteolipid protein in the oligodendrocyte cell membrane.

The orientation of proteins within a cell membrane can often be difficult to determine. A number of models have been proposed for the orientation of the myelin protein, proteolipid protein (PLP), each of which includes exposed domains on the intracellular and extracellular membrane faces. Immunolabeling experiments have localized the C-terminus and the region spanning amino acids 103-116 to the cytoplasmic face of the membrane, but no well characterized antibodies have been available that label extracellular PLP domains. In this report, we describe the generation and characterization of mouse monoclonal antibodies (mAb) against putative extramembrane domains. Three of the mAb, specific for PLP peptides 40-59, 178-191, or 215-232, immunostain live oligodendrocytes, indicating that these regions of the molecule are exposed on the external surface of the cell. In addition, we have used these mAb to study the time-course of incorporation of PLP into the oligodendrocyte membrane. These studies increase our knowledge of the orientation of PLP in the lipid bilayer and are relevant for understanding myelin function.

Amino Acid Sequence↗

PubMed1996

Resumed tooth development following avulsion of a permanent central incisor.

A case is presented in which an upper right central incisor was avulsed because of trauma at age six. At the time of trauma it was suspected that the pulp had remained in the socket although the tooth had been lost. No attempt was made to treat the socket, remove the pulp, or replant the tooth. Follow-up radiography showed that, despite initial apparent complete loss of the calcified portion of the tooth, root development proceeded to completion.

Child↗

PubMed1995

An altered peptide ligand mediates immune deviation and prevents autoimmune encephalomyelitis.

In experimental autoimmune encephalomyelitis (EAE) induced with myelin proteolipid protein (PLP) peptide 139-151, we have previously shown that the disease is mediated by Th1 cells, which recognize tryptophan 144 as the primary TCR contact point. Here we describe an altered peptide ligand (APL), generated by a single amino acid substitution (tryptophan to glutamine) at position 144 (Q144), which inhibits the development of EAE induced with the native PLP 139-151 peptide (W144). We show that the APL induces T cells that are cross-reactive with the native peptide and that these cells produce Th2 (IL-4 and IL-10) and Th0 (IFN gamma and IL-10) cytokines. Adoptive transfer of T cell lines generated with the APL confer protection from EAE. These data show that changing a single amino acid in an antigenic peptide can significantly influence T cell differentiation and suggest that immune deviation may be one of the mechanisms by which APLs can inhibit an autoimmune disease.

Animals↗

PubMed1995

Expression of myelin proteolipid protein in oligodendrocytes and transfected cells.

The data presented in this paper show that the appropriate tools are now available to study the behavior of PLP and DM20 transcripts engineered with either point mutations or deletion of specific domains. Such studies should begin to provide new insights into the functions of PLP and DM20 and their role in relation to the optimal functioning of the nervous system.

Amino Acid Sequence↗

PubMed1995

Loricrin expression is coordinated with other epidermal proteins and the appearance of lipid lamellar granules in development.

In mouse, epidermal development proceeds from a single basal cell layer covered by a specialized single cell layer called the periderm at E14 to a fully differentiated stratified squamous epithelium at E18. To determine when loricrin, a major cell envelope component, is expressed during development, we examined fetal skin from mice of gestational ages E13 through E19 and compared the temporal pattern of loricrin expression with that of other differentiation markers. We found that loricrin mRNA and protein were expressed by E16, following the expression of keratins K1 and K10 and preceding the expression of profilaggrin. Interestingly, both loricrin and profilaggrin were initially expressed focally in areas corresponding to more advanced morphologic stages of maturation. Because the cornified envelope is a composite structure consisting of both protein and lipid components, we also monitored the appearance of lipid lamellar granules during epidermal development. These granules were first evident at E16 and the extrusion of lipids from the granules into the intercellular space occurred at E17, prior to the cross linking of loricrin into the cell envelope. Our results document that loricrin is expressed and accumulates at the cell periphery subsequent to the extrusion of lipids, but prior to processing of profilaggrin. We suggest that the sequential regulation of these events is critical for formation of epidermal barrier function during development.

Animals↗