Immunology Graduate Group
Drew Weissman, M.D., Ph.D.
Assistant Professor, Division of Infectious Diseases, Department of Medicine
Address: 522B Johnson Pavilion
Office Phone: 215-614-0291
Fax: 215-349-5111
Email: dreww@mail.med.upenn.edu
Education:
M.D., Ph.D., Boston University School of Medicine
Research Interests
Immunopathogenesis of HIV infection. Factors affecting the initiation of infection and the control of viral replication. Immunobiology of dendritic cells in HIV disease.
Research Techniques: The laboratory uses a combination of cellular immunology and molecular biology techniques. Primary cells are used in most experiments and are isolated from peripheral blood or tissue. Dendritic cells (DC) are isolated directly from blood or tissue or are induced with cytokines. DNA cassettes containing antigens of interest are used to make mRNA for transfection of antigen-presenting cells. PCR, rtPCR, cytokine and HIV ELISA, in situ hybridization, and flow cytometry are used to evaluate results. We are beginning to use mouse models to study vaccine optimization with antigens including influenza, HIV, and M. tuberculosis.
Research Summary
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| A dendritic cell, the primary and most potent antigen presenting cell (A), when exposed to HIV both binds whole infectious virus on its surface (B, arrows) and internalizes and processes HIV antigens for presentation to T cells. This results in the presentation of virus, other pathogen, and vaccine derived antigenic peptides to CD4+ T cells and, at the same time, the delivery of infectious HIV leading to T cell infection. Thus dramatizing the ingenuity of HIV and the difficulties in developing effective strategies for inducing protective immunity. |
The laboratory uses a combination of cellular immunology and molecular biology techniques. Primary cells are used in most experiments and are isolated from peripheral blood or tissue. Dendritic cells (DC) are isolated directly from blood or tissue or are induced with cytokines. DNA cassettes containing antigens of interest are used to make mRNA for transfection of antigen-presenting cells. PCR, rtPCR, cytokine and HIV ELISA, in situ hybridization, and flow cytometry are used to evaluate results. We are beginning to use mouse models to study vaccine optimization with antigens including influenza, HIV, and M. tuberculosis. Research Summary The lab currently has three major projects related to HIV immunopathogenesis. The first studies antigen presentation by dendritic cells (DC). The goal of this research is to optimize the delivery of candidate antigens to DC and activation of T cells to generate a vaccine/immune adjuvant. We are currently studying mRNA that encodes antigen(s) as a delivery agent for loading DC. Our initial studies have determined that DC can engulf tumor or virally infected cells, process cellular proteins for MHC class II (CD4+ T cell) activation, and extract and translate RNA from the engulfed cell for use in MHC class I (CTL) activation. This observation of the natural use of RNA for delivering antigen to antigen presenting cells along with the safety and efficiency of RNA delivery suggests that RNA based vaccines may be very effective. In vitro studies using antigen encoding mRNA pulsing of DC demonstrates a superior ability to load both MHC class I and II molecules and stimulate T cell responses compared to other antigen delivery methods including peptide, protein or recombinant vaccinia virus. Current studies are investigating the targeting of DC with antigen encoding mRNA in vivo to induce viral and tumor immunity.
The second project studies host and viral factors at the site of heterosexual transmission of HIV, the genital mucosa. HIV in the US and Europe is mainly spread by IV drug use and homosexual contact although heterosexual transmission is increasing (currently 13% of new infections). In Thailand, Asia, and Africa, over 90% of new infections are acquired heterosexually. Genital tract tissues from populations in Thailand, Africa, the Caribbean, and USA are analyzed using PCR, rtPCR, in situ analyses, and immunohistochemical staining for HIV, cytokines, chemokines, and infectious agents. Preliminary studies have identified an infiltration of activated CD4+ T cells expressing high levels of HIV in Thai but not US women (84% versus <10%). This infiltrate presents an attractive model for increased heterosexual spread in Thailand. We are currently analyzing the composition of the infiltrate, the cytokines and HIV coreceptor expression in the tissue, the infectious properties of the virus obtained from the infiltrating T cells, and possible etiologic factors for the infiltrate.
The third project studies the populations of CD4+ T cells that actively replicate HIV during an antigen-specific immune response. We previously demonstrated that during an in vivo immune response to a vaccine or infection, antigen-specific T cells are activated and viral replication increases. Our current data suggests that it is not the antigen-specific cells that replicate HIV. Instead, bystander activated CD4+ T cells are the major source of HIV replication during an antigen-specific response. The mechanisms of bystander activation and protection of antigen-specific from HIV infection are being studied.
Key Words: HIV, dendritic cell, CTL, antigen-presentation, chemokine
Recent Publications
Weissman, D., Li, Y., Orenstein, J.M., Fauci, A.S.: Both a precursor and a mature population of dendritic cells can bind HIV; however, only the mature population that expresses CD80 can pass infection to unstimulated CD4 positive T cells. J Immunol 155:4111-4117, 1995.
Weissman, D., Barker, T.D., Fauci, A.S.: The Efficiency of Acute Infection of CD4 Positive T Cells is Markedly Enhanced in the Setting of Antigen-Specific Immune Activation. J Exp Med. 183:1-6, 1996.
Weissman, D., Fauci, A.S.: Role of dendritic cells in the immunopathogenesis of HIV infection. Current Opinions Microbiology 10:358-367, 1997.
Weissman, D., Rabin, R., Arthros, J., Dybul, M., Rubbert, A., Venkatesan, S., Farber, J., Fauci, A.S.: Macrophage tropic HIV and SIV gp160 signals through CCR5. Nature 389:981-6, 1997.
Weissman, D., Rubbert, A., Combadiere, C., Murphy, P.M., Fauci, A.S.: Dendritic cells express and use multiple HIV coreceptors. Adv Exp Med Biol 417:401-6, 1997.
Rubbert, A., Combadiere, C., Ostrowski, M., Dybul, M., Machado, E., Cohn, M., Hoxie, J.A., Murphy, P.M., Fauci, A.S., Weissman, D.: Dendritic cells express multiple chemokine receptors used by HIV as coreceptors for entry. J Immunol 160:3933-41, 1998.
Goletti, D., Weissman, D., Jackson, R.W., Collins, F., Kinter, A., Fauci, A.S: The in vitro induction of HIV replication in PPD+, HIV-infected individuals by recall antigen response to Mycobacterium tuberculosis is the result of a balance in the secretion of IL-2, proinflammatory and anti-inflammatory cytokines. J Infect Dis 177: 1332-1338, 1998.
Dybul, M., Weissman, D., Rubbert, A., Machado, E., Cohn, M., Fauci, A.S. D32CCR5 dendritic cells transfer M-tropic HIV to wild-type CCR5 CD4+ T cells and T-tropic HIV to autologous CD4+ T cells: DC are not the restriction site for HIV infection in D32CCR5 individuals nor for the restriction of M-tropic HIV primary infection. AIDS Res Hum Retroviruses 14:1109-13, 1998.
Lee, B., Sharron, M., Montaner, L.J., Weissman, D., and Doms, R.W. Quantification of CD4, CCR5, and CXCR4 on lymphocyte subsets, dendritic cells, and differentially conditioned monocyte-derived macrophages. Proc. Natl. Acad, Sci. USA 96:5512-20, 1999.
Weissman, D., Dybul, M., Davey, R.T.Jr., Walker, R.E., Kovacs, J.A. Interleukin-2 Upregulates Expression of the HIV Fusion Coreceptor CCR5 by CD4+ Lymphocytes in vivo. J Infect Dis 181:933-938, 2000.
Cohn, M.A., Frankel, S., Rugpao, S., Vahey, M., Young, M.,Wollett, G., Tovanabutra, S., Suriyanon, V., VanCott, T., Barrick, S., Nelson, K., and Weissman, D. Chronic Vaginal Mucosal Inflammation and HIV Expression: A Mechanism for Increased Heterosexual Transmission of HIV-1. Submitted AIDS.
Weissman, D., Ni, H., Scales, D., Dude, A., Capodici, J., McGibney, K., Abdool, A., Isaacs, S.N., Cannon, G., KarikÑ, K... HIV gag mRNA transfection of dendritic cells delivers encoded antigen to MHC class I and II molecules, causes DC maturation, and induces a potent human in vitro primary immune response. Submitted J. Exp. Med.
Lab Rotation Projects:
1. The study of genetic interference by dsRNA on HIV replication.
2. Analysis of RNA structure and discrete coding sequences on dendritic cell uptake, processing, and antigen presentation of encoded protein.
3. Development of new in situ techniques for analyzing chemokine receptor expression in tissue.
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