Biomedical subjects

Peggy P Ho

Publications and source records attributed to Peggy P Ho.

8 recordsLinked to original sources

PubMed2006

Selective tyrosine kinase inhibition by imatinib mesylate for the treatment of autoimmune arthritis.

Tyrosine kinases play a central role in the activation of signal transduction pathways and cellular responses that mediate the pathogenesis of rheumatoid arthritis. Imatinib mesylate (imatinib) is a tyrosine kinase inhibitor developed to treat Bcr/Abl-expressing leukemias and subsequently found to treat c-Kit-expressing gastrointestinal stromal tumors. We demonstrate that imatinib potently prevents and treats murine collagen-induced arthritis (CIA). We further show that micromolar concentrations of imatinib abrogate multiple signal transduction pathways implicated in RA pathogenesis, including mast cell c-Kit signaling and TNF-alpha release, macrophage c-Fms activation and cytokine production, and fibroblast PDGFR signaling and proliferation. In our studies, imatinib attenuated PDGFR signaling in fibroblast-like synoviocytes (FLSs) and TNF-alpha production in synovial fluid mononuclear cells (SFMCs) derived from human RA patients. Imatinib-mediated inhibition of a spectrum of signal transduction pathways and the downstream pathogenic cellular responses may provide a powerful approach to treat RA and other inflammatory diseases.

Animals↗

PubMed2006

Tolerizing DNA vaccines for autoimmune arthritis.

Current therapies for rheumatoid arthritis (RA) and other autoimmune diseases non-specifically suppress immune function, and there is great need for fundamental approaches such as antigen-specific tolerizing therapy. In this paper we describe development of antigen-specific tolerizing DNA vaccines to treat collagen-induced arthritis (CIA) in mice, and use of protein microarrays to monitor response to therapy and to identify potential additional autoimmune targets for next generation vaccines. We demonstrate that tolerizing DNA vaccines encoding type II collagen (CII) reduced the incidence and severity of CIA. Atorvastatin, a statin drug found to reduce the severity of autoimmunity, potentiated the effect of DNA vaccines encoding CII. Analysis of cytokines produced by collagen-reactive T cells derived from mice receiving tolerizing DNA encoding CII, as compared to control vaccines, revealed reduced production of the pro-inflammatory cytokines IFN-gamma and TNF-alpha. Arthritis microarray analysis demonstrated reduced spreading of autoantibody responses in mice treated with DNA encoding CII. The development of tolerizing DNA vaccines, and the use of antibody profiling to guide design of and to monitor therapeutic responses to such vaccines, represents a promising approach for the treatment of RA and other autoimmune diseases.

Animals↗

PubMed2005

Lipid microarrays identify key mediators of autoimmune brain inflammation.

Recent studies suggest that increased T-cell and autoantibody reactivity to lipids may be present in the autoimmune demyelinating disease multiple sclerosis. To perform large-scale multiplex analysis of antibody responses to lipids in multiple sclerosis, we developed microarrays composed of lipids present in the myelin sheath, including ganglioside, sulfatide, cerebroside, sphingomyelin and total brain lipid fractions. Lipid-array analysis showed lipid-specific antibodies against sulfatide, sphingomyelin and oxidized lipids in cerebrospinal fluid (CSF) derived from individuals with multiple sclerosis. Sulfatide-specific antibodies were also detected in SJL/J mice with acute experimental autoimmune encephalomyelitis (EAE). Immunization of mice with sulfatide plus myelin peptide resulted in a more severe disease course of EAE, and administration of sulfatide-specific antibody exacerbated EAE. Thus, autoimmune responses to sulfatide and other lipids are present in individuals with multiple sclerosis and in EAE, and may contribute to the pathogenesis of autoimmune demyelination.

Animals↗

PubMed2005

Treatment of autoimmune neuroinflammation with a synthetic tryptophan metabolite.

Local catabolism of the amino acid tryptophan (Trp) by indoleamine 2,3-dioxygenase (IDO) is considered an important mechanism of regulating T cell immunity. We show that IDO transcription was increased when myelin-specific T cells were stimulated with tolerogenic altered self-peptides. Catabolites of Trp suppressed proliferation of myelin-specific T cells and inhibited production of proinflammatory T helper-1 (T(H)1) cytokines. N-(3,4,-Dimethoxycinnamoyl) anthranilic acid (3,4-DAA), an orally active synthetic derivative of the Trp metabolite anthranilic acid, reversed paralysis in mice with experimental autoimmune encephalomyelitis, a model of multiple sclerosis (MS). Trp catabolites and their derivatives offer a new strategy for treating T(H)1-mediated autoimmune diseases such as MS.

Adoptive Transfer↗

PubMed2005

A suppressive oligodeoxynucleotide enhances the efficacy of myelin cocktail/IL-4-tolerizing DNA vaccination and treats autoimmune disease.

Targeting pathogenic T cells with Ag-specific tolerizing DNA vaccines encoding autoantigens is a powerful and feasible therapeutic strategy for Th1-mediated autoimmune diseases. However, plasmid DNA contains abundant unmethylated CpG motifs, which induce a strong Th1 immune response. We describe here a novel approach to counteract this undesired side effect of plasmid DNA used for vaccination in Th1-mediated autoimmune diseases. In chronic relapsing experimental autoimmune encephalomyelitis (EAE), combining a myelin cocktail plus IL-4-tolerizing DNA vaccine with a suppressive GpG oligodeoxynucleotide (GpG-ODN) induced a shift of the autoreactive T cell response toward a protective Th2 cytokine pattern. Myelin microarrays demonstrate that tolerizing DNA vaccination plus GpG-ODN further decreased anti-myelin autoantibody epitope spreading and shifted the autoreactive B cell response to a protective IgG1 isotype. Moreover, the addition of GpG-ODN to tolerizing DNA vaccination therapy effectively reduced overall mean disease severity in both the chronic relapsing EAE and chronic progressive EAE mouse models. In conclusion, suppressive GpG-ODN effectively counteracted the undesired CpG-induced inflammatory effect of a tolerizing DNA vaccine in a Th1-mediated autoimmune disease by skewing both the autoaggressive T cell and B cell responses toward a protective Th2 phenotype. These results demonstrate that suppressive GpG-ODN is a simple and highly effective novel therapeutic adjuvant that will boost the efficacy of Ag-specific tolerizing DNA vaccines used for treating Th1-mediated autoimmune diseases.

Amino Acid Sequence↗

PubMed2004

Immunity to the extracellular domain of Nogo-A modulates experimental autoimmune encephalomyelitis.

Nogo-66, the extracellular 66 aa loop of the Nogo-A protein found in CNS myelin, interacts with the Nogo receptor and has been proposed to mediate inhibition of axonal regrowth. It has been shown that immunization with Nogo-A promotes recovery in animal models of spinal cord injury through induction of Ab production. In this report, studies were performed to characterize the immune response to Nogo-66 and to determine the role of Nogo in experimental autoimmune encephalomyelitis (EAE). Immunization of EAE-susceptible mouse strains with peptides derived from Nogo-66 induced a CNS immune response with clinical and pathological similarities to EAE. The Nogo-66 peptides elicited strong T cell responses that were not cross-reactive to other encephalitogenic myelin Ags. Using a large scale spotted microarray containing proteins and peptides derived from a wide spectrum of myelin components, we demonstrated that Nogo-66 peptides also generated a specific Ab response that spreads to several other encephalitogenic myelin Ags following immunization. Nogo-66-specific T cell lines ameliorated established EAE, via Nogo-66-specific Th2 cells that entered the CNS. These results indicate that some T cell and B cell immune responses to Nogo-66 are associated with suppression of ongoing EAE, whereas other Nogo-66 epitopes can be encephalitogenic.

Adoptive Transfer↗

PubMed2004

The neurite outgrowth inhibitor Nogo A is involved in autoimmune-mediated demyelination.

Inhibitors associated with CNS myelin are thought to be important in the failure of axons to regenerate after spinal cord injury and in other neurodegenerative disorders. Here we show that targeting the CNS-specific inhibitor of neurite outgrowth Nogo A by active immunization blunts clinical signs, demyelination and axonal damage associated with experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS). Mice vaccinated against Nogo A produce Nogo-specific antibodies that block the neurite outgrowth inhibitory activity associated with CNS myelin in vitro. Passive immunization with anti-Nogo IgGs also suppresses EAE. Our results identify Nogo A as an important determinant of the development of EAE and suggest that its blockade may help to maintain and/or to restore the neuronal integrity of the CNS after autoimmune insult in diseases such as MS. Our finding that Nogo A is involved in CNS autoimmune demyelination indicates that this molecule may have a far more complex role than has been previously anticipated.

Animals↗

PubMed2003

An immunomodulatory GpG oligonucleotide for the treatment of autoimmunity via the innate and adaptive immune systems.

Bacterial DNA and immunostimulatory CpG oligodeoxynucleotides (ODNs) activate the innate immune system to produce proinflammatory cytokines. Shown to be potent Th1-like adjuvants, stimulatory CpG motifs are currently used as effective therapeutic vaccines for various animal models of infectious diseases, tumors, allergies, and autoimmune diseases. In this study, we show that the application of an immunomodulatory GpG ODN, with a single base switch from CpG to GpG, can effectively inhibit the activation of Th1 T cells associated with autoimmune disease. Moreover, this immunomodulatory GpG ODN suppresses the severity of experimental autoimmune encephalomyelitis in mice, a prototypic Th1-mediated animal disease model for multiple sclerosis.

Adjuvants, Immunologic↗