Summary: The role of prion proteins in autoimmunity
Multiple sclerosis (MS) is an inflammatory, demyelinating, neurodegenerative disorder of the central nervous system (CNS). The purpose of this grant is to study the role of prion protein (PrP) in CNS autoimmune disease. PrP refers both to the endogenous cellular variant prion protein (PrPc) and to the abnormal conformational state PrpSc. In this proposal, PrP will be used synonymously with PrPc. PrP is expressed at in neurons, as well as in cells of the immune system, including dendritic cells, macrophages, and T cells. The main biological role of PrP remains unknown. Our own preliminary results indicate that certain genotypes of the PrP gene (Prnp) occur significantly for frequently in patients with severe relapsing-remitting MS (RRMS) and mild RRMS than in healthy controls. In addition, our preliminary data indicates that the absence of PrP in mice leads to worsening of experimental autoimmune encephalomyelitis (EAE), and animal model of MS. The goal of the proposed research is to elucidate the role of PrP as it relates to MS and EAE, and to better characterize it as a disease modifier in CNS autoimmune disease. We will test the hypothesis that PrP plays an important biological role in the regulation of antigen-specific peripheral T cell responses leading to EAE. We also hypothesize that there are differences in Prnp 129 allele frequencies between patients with mild or severe forms of MS. To test immunoregulatory properties of PrP in EAE, we will actively induce EAE in PrP-/- mice and WT mice. Antigen-specific proliferative responses and cytokine expression by splenocytes from PrP-/- and WT mice will be measured. The effects of monoclonal IgG antibodies and single-chain Fv fragments against PrP will be tested in vivo and in vitro. To evaluate the specific function of PrP on T lymphocytes in EAE, reciprocal adoptive transfer of antigen-specific T cells will be conducted between PrP-/- and WT mice. CNS-infiltrating T cells will be analyzed immediately ex-vivo with regard to activation status and cytokine profile by flow cytometry and intracellular cytokine staining. The molecular and cellular effects of PrP on T cell receptor (TCR) signaling will be studied using a CD4+ T cell clone and altered myelin basic peptides (APL). To evaluate the role of Prnp 129 polymorphisms as a disease modifier of MS, we will assess allele frequency of Prnp 129 in patients with RRMS. Allele frequencies will be compared with those of various reference populations. Then, we will evaluate the effect of Prnp 129 genotypes MM, VV, and MV on the prevalence of benign versus severe RRMS. The association of Prnp 129 polymorphisms to disease progression from RRMS to secondary-progressive MS (SPMS), and its impact on surrogate disease markers on MRI will also be studied. In summary, this is the first systematic attempt to study the role of PrP in CNS autoimmune disease. The experimental approach includes several in vivo and in vitro assays that will test the immunoregulatory role of PrP in T cells in EAE. Another goal of the proposed experiments is to test the feasibility of anti-PrP pharmacotherapy in CNS autoimmune diseases. Testing for Prnp 129 polymorphisms may eventually have a major impact on therapy and monitoring of MS.
Summary: T cell adhesion and activation
Multiple sclerosis (MS) is an autoimmune disease of the brain and spinal cord. It is currently thought that white blood cells of an individual?s own immune system become self-reactive, and start to attack proteins in the brain. In order to get to the brain and spinal cord, these self-reactive white blood cells have to attach to the blood vessel wall first. Natalizumab (?Tysabri) is approved for the treatment of relapsing forms of MS. Tysabri is a protein that interferes with the binding of white blood cells to blood vessels. Thus, Tysabri keeps these cells out of the brain. Not only self-reactive white blood cells, but possibly other cells of the immune system, including the ones that fight infections and cancer may no longer be able to migrate from the blood into tissues. Unfortunately, two MS patients and one patient with Crohn?s disease treated with Tysabri developed progressive multifocal leukoencephalopathy (PML), an infection of the brain with the polyoma virus JC. PML is almost always fatal, and there is currently no effective therapy. Two of the three patients treated with Tysabri who developed PML died. Our group showed that Tysabri affects subtypes of white blood cells differently in their ability to migrate from the blood into the brain. We also observed that the effect of Tysabri on white blood cells lasts substantially longer than expected. Even six months after treatment of Tysabri was stopped, the numbers of white blood cells that we could detect in the brain were as low as in patients who were still taking Tysabri. We also were able to obtain the brain of the patient that had died of PML under Tysabri therapy, and we demonstrated that the composition of white blood cells in brain tissue of this patient was significantly altered. Interestingly, we saw that the numbers of white blood cells that were previously not known to be affected by Tysabri were also decreased. Some of these cells may be critical in fighting off infections and cancerous growth in the brain. In this grant proposal, we will study in great detail how agents like Tysabri change the way the immune system may respond to self tissue or other proteins. We will use similar drugs in an animal model of MS. Also, we will generate genetically altered mice that will allow us to address some of these important issues. Specifically, we will study how drugs like Tysabri impact the development of white blood cells that may be necessary to fight infections and cancerous cells, and which of these cells precisely are being kept out of the brain and spinal cord.
RESEARCH INTERESTS
The role of prion protein as a disease modifier in autoimmune diseases of the central nervous system
The role of prion protein as a disease modifier in autoimmune diseases of the central nervous system
Peroxisome proliferator-activated receptor agonists as treatment for autoimmune demyelination
The role of prion protein as a disease modifier in autoimmune diseases of the central nervous system
T cell activation requirement in autoimmune demyelination
RECENT PUBLICATIONS
Watson NF, Woo D, Doherty MJ, Frohman EM, Racke MK, De Baets M, Hartung H-P, Kieseier BC, Stuve O., "Humoral immune responses after rabies infection" Archives of Neurology, 64:1355-6, 2007
Yao K, Gagnon S, Akhyani N, Williams E, Fotheringham J, Frohman EM, Stuve O, Monson N, Racke MK, Jacobson S, "Reactivation of Human Herpesvirus-6 in natalizumab treated multiple sclerosis patients" PLoS ONE, 30:e2028, 2008
Martin MdelP, Cravens PD, Winger R, Frohman EM, Racke MK, Eagar TN, Monson NL, Zamvil SS, Weber MS, Hemmer B, Karandikar NJ, Kleinschmidt-DeMasters BK, Stuve O, "Natalizumab decreases the numbers of dendritic cells and CD4+ T cells in cerebral perivascular spaces" Archives of Neurology, In press
Stuve O, Cravens PD, Frohman EM, Phillips JT, Remington GM, von Geldern G, Cepok S, Singh MP, Cohen Tervaert JW, De Baets M, MacManus D, Miller DH, Radu EW, Cameron EM, Monson NL, Zhang S, Kim R, Hemmer B, Racke MK, "Immunological and clinical status 14 months after cessation of natalizumab therapy" Neurology, In press
Park S, Ramnarain DB, Hatanpaa KJ, Mickey BE, Saha D, Paulmurugan R, Madden CJ, Wright PS, Bhai S, Ali MA, Puttaparthi K, Hu W, Elliott JL, Stuve O, Habib AA, "The death domain containing kinase RIP1 regulates p27Kip1 levels via a PI3K-Akt-Forkhead pathway" EMBO reports, In press
SIGNIFICANT PUBLICATIONS
Stuve O, Youssef S, Weber MS, Nessler S, von Budingen H-C, Hemmer B, Sobel RA, Steinman L, Zamvil SS, "Immunomodulatory synergy by combination of atorvastatin and glatiramer acetate in treatment of CNS autoimmunity" Journal of Clinical Investigation, 116:1037-1044, 2006
Stuve O, Marra CM, Jerome KR, Cook L, Cravens PD, Cepok S, Frohman EM, Phillips JT, Arendt G, Hemmer B, Monson NL, Racke MK, "Immune surveillance in multiple sclerosis patients treated with natalizumab" Annals of Neurology, 59:743-747, 2006
Stuve O, Marra CM, Bar-Or A, Niino M, Cravens PD, Cepok S, Frohman EM, Phillips JT, Arendt G, Jerome KR, Cook L, Grand’Maison F, Hemmer B, Monson NL, Racke MK, "Altered CD4+/CD8+ T cells ratios in cerebrospinal fluid of natalizumab-treated patients with multiple sclerosis" Archives of Neurology, 63:1383-1387, 2006
Martin MdelP, Cravens PD, Winger R, Frohman EM, Racke MK, Eagar TN, Monson NL, Zamvil SS, Weber MS, Hemmer B, Karandikar NJ, Kleinschmidt-DeMasters BK, Stuve O, "Natalizumab decreases the numbers of dendritic cells and CD4+ T cells in cerebral perivascular spaces" Archives of Neurology, In press
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