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S D Miller

Publications and source records attributed to S D Miller.

At least 73 records · Page 4Linked to original sources
PubMed1998

Tissue-specific up-regulation of B7-1 expression and function during the course of murine relapsing experimental autoimmune encephalomyelitis.

B7/CD28-mediated costimulation is a promising target for therapeutic intervention in autoimmune diseases. However, studies addressing the differential functional roles of B7-1 and B7-2 in several autoimmune models have resulted in conflicting data, perhaps due to the temporal dynamics of B7-1 and B7-2 surface expression on different cell types and/or at different sites during an autoimmune response. We examined the temporal expression of B7 costimulatory molecules in the CNS and in various lymphoid organs during the course of murine relapsing-remitting experimental autoimmune encephalomyelitis (R-EAE). Following immunization of SJL mice with the immunodominant proteolipid protein epitope, PLP139-151, surface expression of B7-1 was up-regulated on B cells, T cells, and macrophages, relative to B7-2, on CNS-infiltrating cells and on splenocytes. Similar enhancement in splenic B7-1 expression could be induced in SJL mice by the adoptive transfer of PLP139-151-specific cells or by immunization with CFA alone. These changes were not observed on lymph node cells, including those isolated from lymph nodes draining the immunization site, which maintained the predominant B7-2 expression pattern seen in naive mice. These phenotypic expression patterns correlated with the functional predominance of B7-1 in costimulating T cell activation when employing APCs from the spleen or CNS of mice with ongoing R-EAE, while B7-2 remained functionally predominant on lymph node APCs. Variation of phenotypic expression and functional dominance of costimulatory molecule expression in different lymphoid compartments during an active inflammatory autoimmune response has important implications in immune regulation, autoimmune pathogenesis, and therapeutic strategies.

Animals↗
PubMed1998

Presentation of proteolipid protein epitopes and B7-1-dependent activation of encephalitogenic T cells by IFN-gamma-activated SJL/J astrocytes.

There is controversy regarding the possible role of glial cells as APCs in the pathogenesis of central nervous system (CNS) demyelinating diseases such as multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). Microglia have been clearly shown to present Ag in the CNS, and due to the proximity of activated astroglial cells to infiltrating T cells and macrophages in demyelinating lesions, it is also possible that astrocytes positively or negatively regulate disease initiation and/or progression. We examined the capacity of IFN-gamma-treated astrocytes from EAE-susceptible SJL/J mice to process and present myelin epitopes. IFN-gamma activation up-regulated ICAM-1, VCAM-1, MHC class II, invariant chain, H2-M, CD40, and B7-1 as determined by FACS and/or RT-PCR analyses. B7-2 expression was only marginally enhanced on SJL/J astrocytes. Consistent with the expression of these accessory molecules, IFN-gamma-treated SJL/J astrocytes induced the B7-1-dependent activation of Th1 lines and lymph node T cells specific for the immunodominant encephalitogenic proteolipid protein (PLP) epitope (PLP139-151) as assessed by proliferation and activation for the adoptive transfer of EAE. Interestingly, IFN-gamma-activated astrocytes efficiently processed and presented PLP139-151, but not the subdominant PLP178-191, PLP56-70, or PLP104-117 epitopes, from intact PLP and a recombinant variant fusion protein of PLP (MP4). The data are consistent with the hypothesis that astrocytes in the proinflammatory CNS environment have the capability of activating CNS-infiltrating encephalitogenic T cells specific for immunodominant epitopes on various myelin proteins that may be involved in either the initial or the relapsing stages of EAE.

Adoptive Transfer↗
PubMed1998

Effect of disease stage on clinical outcome after syngeneic bone marrow transplantation for relapsing experimental autoimmune encephalomyelitis.

Relapsing experimental autoimmune encephalomyelitis (R-EAE) is an immune-mediated demyelinating central nervous system (CNS) disease. Myeloablation and syngeneic bone marrow transplantation (SBMT), when performed at the peak of acute disease (day 14), prevented glial scarring and ameliorated the disease severity. In contrast, when syngeneic BMT was performed late in chronic phase (day 78), significant glial scarring remained and the clinical severity did not differ significantly from that of the controls. After SBMT in either the acute or chronic phase of disease, the posttransplant immune system remained responsive to myelin epitopes as determined by in vitro proliferation and interferon-gamma (IFN-gamma) production. However, in mice undergoing SBMT, in vivo delayed-type hypersensitivity (DTH) responses were significantly decreased while IFN-gamma RNA levels and inflammatory infiltrates within the CNS were slightly improved. We conclude that failure of SBMT to improve the clinical disease when performed in chronic phase may be due to preexisting glial scarring. We also conclude that in the absence of glial scarring and irreversible neuronal injury, in vivo DTH responses and histology are better predictors of clinical improvement than in vitro proliferation or IFN-gamma cytokine production.

Animals↗
PubMed1998

Epitope spreading: lessons from autoimmune skin diseases.

Autoimmune diseases are initiated when patients develop aberrant T and/or B cell responses against self proteins. These responses presumably are directed to single immunogenic epitopes on these proteins. Recent data in animal models of autoimmune diseases suggest that the targets of immune responses in autoimmunity do not remain fixed, but can be extended to include other epitopes on the same protein or other proteins in the same tissue, a phenomenon termed "epitope spreading." The "epitope spreading" phenomenon also applies to situations in which tissue damage from a primary inflammatory process causes the release and exposure of a previously "sequestered" antigen, leading to a secondary autoimmune response against the newly released antigen. In experimental autoimmune animal diseases, "epitope spreading" seems to have significant physiologic importance in determining the course and duration of disease. In this paper, we review the current concepts in animal models of autoimmune diseases in order to define the "epitope spreading" phenomenon, and we then propose how this phenomenon might play a significant role in the development and the course of autoimmune skin diseases. Hopefully, an understanding of "epitope spreading" will help the dermatology community to better understand the pathogenesis of autoimmune skin diseases and to rationally fashion disease-specific immune therapy in the future.

Animals↗
PubMed1998

Periductal mastitis. Masquerading as carcinoma.

Periductal mastitis (mammary duct ectasia) is a little appreciated, often unrecognized entity that may present to the dermatologist. We present our experience with this disease and hope to familiarize the reader with a condition not well known to most dermatologists. Periductal mastitis is a benign mammary duct disease that begins with periductal inflammation and progresses to ductal dilatation with minimal inflammation (ductal ectasia). The clinical and radiographic appearance of this disease can be indistinguishable from carcinoma of the breast.

Aged↗
PubMed1998

The functional significance of epitope spreading and its regulation by co-stimulatory molecules.

Epitope spreading is a process whereby epitopes distinct from and non-cross-reactive with an inducing epitope become major targets of an ongoing immune response. This phenomenon has been defined in experimental and natural situations as a consequence of acute or persistent infection and secondary to chronic tissue destruction that occurs during progressive autoimmune disease. We have investigated the functional significance of this process in the chronic stages of both autoimmune and virus-induced central nervous system (CNS) demyelinating disease models in the SJL/J mouse. During the relapsing-remitting course of experimental autoimmune encephalomyelitis (R-EAE) induced with defined encephalitogenic myelin peptides, CD4+ T cells specific for endogenous epitopes on both the initiating myelin protein (intramolecular epitope spreading) and distinct myelin proteins (intermolecular epitope spreading) are primed secondary to myelin destruction during acute disease and play a major functional role in mediating disease relapses. Similarly, epitope spreading to endogenous myelin epitopes appears to play a major functional role in the chronic-progressive course of Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD), a virus-induced CD4+ T-cell-mediated immunopathology. In TMEV-IDD, myelin destruction is initiated by virus-specific CD4+ T cells which target virus epitopes persisting in CNS-derived antigen-presenting cells. However, the chronic stage of this progressive disease is associated with the activation of CD4+ T cells specific for multiple myelin epitopes. In both models, the temporal course of T-cell activation occurs in a hierarchical order of epitope dominance, spreading first to the most immunodominant epitope and progressing to lesser immunodominant epitopes. In addition, epitope spreading in R-EAE is regulated predominantly by CD28/B7-1 co-stimulatory interactions, as antagonism of B7-1-mediated co-stimulation using anti-B7-1 F(ab) fragments is an effective ameliorative therapy for ongoing disease. The process of epitope spreading has obvious important implications for the design of antigen-specific therapies for the treatment of autoimmune disease since these therapies will have to identify and target endogenous self epitopes associated with chronic tissue destruction.

Animals↗
PubMed1998

Characterization of and functional antigen presentation by central nervous system mononuclear cells from mice infected with Theiler's murine encephalomyelitis virus.

We examined the phenotype and function of cells infiltrating the central nervous system (CNS) of mice persistently infected with Theiler's murine encephalomyelitis virus (TMEV) for evidence that viral antigens are presented to T cells within the CNS. Expression of major histocompatibility complex (MHC) class II in the spinal cords of mice infected with TMEV was found predominantly on macrophages in demyelinating lesions. The distribution of I-As staining overlapped that of the macrophage marker sialoadhesin in frozen sections and coincided with that of another macrophage/microglial cell marker, F4/80, by flow cytometry. In contrast, astrocytes, identified by staining with glial fibrillary acidic protein, rarely expressed detectable MHC class II, although fibrillary gliosis associated with the CNS damage was clearly seen. The costimulatory molecules B7-1 and B7-2 were expressed on the surface of most MHC class II-positive cells in the CNS, at levels exceeding those found in the spleens of the infected mice. Immunohistochemistry revealed that B7-1 and B7-2 colocalized on large F4/80(+) macrophages/microglia in the spinal cord lesions. In contrast, CD4(+) T cells in the lesions expressed mainly B7-2, which was found primarily on blastoid CD4(+) T cells located toward the periphery of the lesions. Most interestingly, plastic-adherent cells freshly isolated from the spinal cords of TMEV-infected mice were able to process and present TMEV and horse myoglobin to antigen-specific T-cell lines. Furthermore, these cells were able to activate a TMEV epitope-specific T-cell line in the absence of added antigen, providing conclusive evidence for the endogenous processing and presentation of virus epitopes within the CNS of persistently infected SJL/J mice.

Amino Acid Sequence↗
PubMed1998

Regulation of the effector stages of experimental autoimmune encephalomyelitis via neuroantigen-specific tolerance induction. III. A role for anergy/deletion.

Our previous work has shown that specific peripheral immune tolerance induced by the intravenous administration of ECDI-fixed, antigen-coupled syngeneic splenocytes is an extremely efficient method for prevention and treatment of chronic relapsing experimental autoimmune encephalomyelitis (R-EAE) in susceptible SJL/J mice. The current study examined the mechanisms by which unresponsiveness is induced in primed encephalitogenic T cells. The results indicate that the inhibition of MBP-specific T cells by the i.v. injection of MBP-coupled splenocytes is not due to the induction of antigen-specific regulatory T cells, but rather to the induction of anergy/deletion of the effector cells. This conclusion is supported by the findings that spleen or lymph node cells isolated from MBP-tolerant mice fail to inhibit the adoptive transfer of R-EAE in cotransfer assays, and that tolerance is not inhibited by prior thymectomy or prior treatment with cyclophosphamide or anti-CD8 monoclonal antibody. In contrast, we demonstrate that splenocytes from MBP-tolerized, asymptomatic mice have a significantly reduced ability to serially transfer R-EAE to naive secondary recipients following antigen re-activation in vitro, in the first several weeks following tolerization, but that the ability to serially transfer R-EAE returns to sham tolerant control levels within 1-2 months. We also demonstrate a significantly reduced precursor frequency of MBP-specific, IL-2-producing T cells in the MBP-tolerant within three days of treatment. Collectively, the data most closely support a model wherein inhibition of MBP-specific encephalitogenic CD4+ effector T cells by i.v. injected MBP-coupled splenocytes is due to the direct induction of anergy/deletion from which they can recover over time.

Adoptive Transfer↗
PubMed1997

Induction of antigen-specific tolerance for the treatment of ongoing, relapsing autoimmune encephalomyelitis: a comparison between oral and peripheral tolerance.

Experimental autoimmune encephalomyelitis (EAE) is a T cell-mediated autoimmune demyelinating disease of the central nervous system that serves as an animal model for multiple sclerosis. Various forms of Ag-specific tolerance have been used prophylactically to prevent development of acute EAE. Here we compare the induction of Ag-specific tolerance using two regimens, proteolipid protein 139-151 (PLP139-151) peptide-coupled splenocytes and oral administration of PLP139-151, for efficacy in the reduction of established, chronic clinical EAE. PLP139-151-coupled splenocytes and not oral administration of PLP139-151 was able to down-regulate established EAE, including subsequent relapses. PLP139-151 peptide-coupled splenocytes were effective at reducing Ag-specific T cell proliferation and IL-2 and IFN-gamma production, while concomitantly increasing IL-4 production. Oral administration of PLP139-151 did not reduce IL-2 or IFN-gamma production and appeared to increase Ag-specific T cell proliferation. Neither multiple high nor low doses of PLP139-151 were effective at decreasing ongoing clinical EAE or PLP139-151-specific IL-2 and IFN-gamma production. These results suggest that PLP139-151 peptide-induced tolerance is an efficacious treatment for ongoing, R-EAE when the peptide is coupled to chemically fixed splenocytes and not when given orally.

Administration, Oral↗
PubMed1997

An accessory protein of DNA polymerase alpha declines in function with increasing age.

Isoforms of DNA polymerase alpha (pol alpha/primase; pol alpha) were isolated from the livers of C57BL/6 mice either 3 months old (young) or 13 months old (mature). The 13-month-old mice were from two groups, one in which food was available ad libitum (AL), and one in which calories had been restricted to 60% of the AL intake (CR). The polymerases from young vs. mature and CR vs. AL mice differed in total and specific pol alpha activity, with the highest values exhibited by enzymes from 3-month-old mice. A more active isoform of pol alpha was typically isolated from CR animals than from AL animals. Differences in charge were used to chromatographically separate pol alpha into elution peaks exhibiting differing degrees of enzyme activity. DNA pol alpha isolated from tissues of mature mice exhibited a decline in activity which was not associated with decreased recoverable levels of pol alpha protein, but with a decline in the tendency of pol alpha to co-purify with an accessory protein, alpha AP, that binds double-stranded DNA (dsDNA). Low activity pol alpha isoforms which did not co-purify with alpha AP were stimulated by interaction with exogenous alpha AP. Pol alpha isoforms which co-purified with the dsDNA-binding accessory protein exhibited higher specific activity and less enhancement of activity upon interaction with exogenous alpha AP. Calorie restricted animals exhibited a pol alpha isoform that was more like pol alpha from younger animals in that it typically copurified with alpha AP, the DNA-binding accessory protein.

Aging↗
PubMed1997

IFN-gamma-activated primary murine astrocytes express B7 costimulatory molecules and prime naive antigen-specific T cells.

Astrocytes may serve as effectual APCs for T cell-mediated immune responses to myelin components during multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). Although astrocytes have been reported not to constitutively express MHC class II molecules, expression is up-regulated during active EAE and by in vitro incubation with IFN-gamma. Previous studies have reported that cytokine-activated astrocytes are able to activate Ag-specific previously activated T cells, but not naive alloreactive T cells. In the current study, we show that a subset of primary murine astrocytes constitutively expresses B7-2 molecules, as determined by FACS and PCR analyses, and up-regulates surface expression and mRNA levels of both B7-2 and B7-1 upon IFN-gamma stimulation. In contrast to earlier reports, we found that both untreated and IFN-gamma-treated astrocytes were able to stimulate proliferation of previously activated OVA-specific Th1 cells. In contrast, only IFN-gamma-treated astrocytes activated naive, transgenic OVA-specific T cells. Astrocyte-induced activation of both OVA-specific naive T cells and activated Th1 cells was dependent primarily on B7-2-mediated costimulation, as proliferation was inhibited by CTLA4-Ig and by anti-B7-2 mAbs. These results suggest that astrocytes in an inflammatory environment have the capacity to express the required MHC class II and B7 costimulatory molecules necessary for efficient activation of naive T cells. Since we have shown that T cells specific for endogenous myelin epitopes released during acute EAE play the major pathologic effector role in subsequent disease relapses (epitope spreading), astrocytes could play a role in the local activation and expansion of these responses.

Abatacept↗
PubMed1997

Degenerate antigen recognition by CD4+ effector T cells in experimental autoimmune encephalomyelitis.

Peptide-specific tolerance with PLP139-151 peptide analogs was used to compare the fine antigen-specificity requirements at both the inductive and effector phases of relapsing EAE (R-EAE). A PLP139-151 analog peptide containing a single substitution at the primary T cell receptor (TcR) contact residue (A144) did not induce proliferation in PLP139-151-primed CD4+ T cells. In addition, tolerance induced with ECDI-treated. A144-coupled splenocytes failed to prevent the inductive phase of PLP139-151-induced R-EAE or to inhibit the induction of peptide-specific DTH indicating that naive PLP139-151-specific T cells do not react with the A144 peptide analog. In contrast, A144-coupled splenocytes did prevent the expression of the effector phase of R-EAE and inhibited the elicitation of peptide-specific DTH responses upon administration to mice seven days after immunization with PLP139-151. The results provide in vivo evidence that "antigen-experienced' T cells recognize a broader repertoire of antigens than do naive T cells and have important implications for the regulation of immune responses and for advancing our understanding of the pathogenesis and treatment of autoimmune disease.

Amino Acid Sequence↗
PubMed1997

Treatment with intact anti-B7-1 mAb during disease remission enhances epitope spreading and exacerbates relapses in R-EAE.

PLP139-151-induced experimental autoimmune encephalomyelitis in the SJL mouse is a Th1-mediated inflammatory demyelinating disease characterized by a relapsing-remitting clinical course (R-EAE). Clinical relapses are mediated by T cells specific for a non-cross reactive secondary PLP epitope (PLP178-191) induced by epitope spreading. We have previously shown that B7-1 expression is upregulated in SJL mice undergoing R-EAE and in vivo treatment during remission with F(ab) fragments of anti-B7-1 mAb, blocked epitope spreading and disease progression. In contrast, the present study shows that treatment with intact anti-B7-1 mAb exacerbated clinical disease relapses and enhanced CNS demyelination. Anti-B7-1-treated mice showed enhanced in vivo delayed-type hypersensitivity (DTH) to the relapse-associated PLP178-191 epitope and responses to the immunodominant MBP84-104 epitope which are absent in the controls. Thus, ligation of B7-1 by intact mAbs has effects opposite to those of anti-B7-1 F(ab) fragments suggesting that the mAb is directly signaling through B7-1 expressed on T cells and/or APCs.

Animals↗
PubMed1997

Persistent infection with Theiler's virus leads to CNS autoimmunity via epitope spreading.

Multiple sclerosis (MS) is a T cell-mediated autoimmune demyelinating disease, which may be initiated by a virus infection. Theiler's murine encephalomyelitis virus (TMEV), a natural mouse pathogen, is a picornavirus that induces a chronic, CD4+ T cell-mediated demyelinating disease with a clinical course and histopathology similar to that of chronic progressive MS (ref. 3). Demyelination in TMEV-infected mice is initiated by a mononuclear inflammatory response mediated by virus-specific CD4+ T cells targeting virus, which chronically persists in the CNS (ref. 4-6). We show that beginning 3-4 weeks after disease onset, T-cell responses to multiple myelin autoepitopes arise in an ordered progression and may play a pathologic role in chronic disease. Kinetic and functional studies show that T-cell responses to the immunodominant myelin proteolipid protein epitope (PLP139-151) did not arise because of cross-reactivity between TMEV and self epitopes (that is, molecular mimicry), but because of de novo priming of self-reactive T cells to sequestered autoantigens released secondary to virus-specific T cell-mediated demyelination (that is, epitope spreading). Epitope spreading is an important alternate mechanism to explain the etiology of virus-induced organ-specific autoimmune diseases.

Amino Acid Sequence↗
PubMed1997

Complex formation between p53 and replication protein A inhibits the sequence-specific DNA binding of p53 and is regulated by single-stranded DNA.

Human replication protein A (RP-A) (also known as human single-stranded DNA binding protein, or HSSB) is a multisubunit complex involved in both DNA replication and repair. Potentially important to both these functions, it is also capable of complex formation with the tumor suppressor protein p53. Here we show that although p53 is unable to prevent RP-A from associating with a range of single-stranded DNAs in solution, RP-A is able to strongly inhibit p53 from functioning as a sequence-specific DNA binding protein when the two proteins are complexed. This inhibition, in turn, can be regulated by the presence of various lengths of single-stranded DNAs, as RP-A, when bound to these single-stranded DNAs, is unable to interact with p53. Interestingly, the lengths of single-stranded DNA capable of relieving complex formation between the two proteins represent forms that might be introduced through repair and replicative events. Increasing p53 concentrations can also overcome the inhibition by steady-state levels of RP-A, potentially mimicking cellular points of balance. Finally, it has been shown previously that p53 can itself be stimulated for site-specific DNA binding when complexed through the C terminus with short single strands of DNA, and here we show that p53 stays bound to these short strands even after binding a physiologically relevant site. These results identify a potential dual role for single-stranded DNA in the regulation of DNA binding by p53 and give insights into the p53 response to DNA damage.

Amino Acid Sequence↗