Ph.D. University of Rochester, 2002
142 Morrison Center
Our research project is focused on the host immune response to viral infections. Primarily, we use mouse models of influenza infection to understand how CD4 T cells are activated during infection and the mechanisms employed by these cells to help clear infectious virus. We also use a T cell receptor (TCR) transgenic (Tg) mouse model in which all of the CD4 T cells recognize a piece of the influenza virus and various “knock-out” mouse strains lacking important immune response genes to determine which type of CD4 T cell is important to provide protection against highly pathogenic influenza infections. Delineating the mechanisms whereby CD4 T cells provide protection to lethal influenza infections will further our understanding of CD4 T cell biology and provide a framework for developing novel vaccine formulations to combat highly pathogenic and emerging influenza virus strains.
In vitro studies: This project aims at understanding the activation and differentiation of a novel CD4 T cell subset that can kill virally infected cells. T cells have been subdivided into CD8+ and CD4+ subsets based on the way that they recognize antigen and the functions that they perform. CD8 cells require class I protein molecules to present peptides to the TCR and are known to destroy virally infected cells via perforin and granzyme secretion. CD4 cells recognize antigen within class II proteins and secrete cytokines that are important for driving B cell antibody production. Previous work from our laboratory has demonstrated that CD4 T cells can also kill influenza peptide expressing target cells via a perforin and granzyme mechanism, suggesting that these cells can help clear infectious virus from the respiratory tract. We have also determined that CD4 cells can use either perforin, or the Fas:FasL system to induce apoptosis in target cells and the cytokine that regulates this activity is the growth factor, IL-2. Furthermore, antigen presenting cells (APC), either B cells or dendritic cells (DC), are necessary for the development of cytolytic activity by CD4 cells in vitro and we hypothesize that DC drive perforin mediated cytolytic activity exclusively.
Studies that are currently underway include:
1) Using TCR Tg mice and mice deficient in perforin to determine how IL-2 can regulate the
development of perforin-mediated vs FasL-mediated cytotoxicity.
2) To determine the key molecule (cytokine or surface protein) expressed by B cells and DC that
directs the differentiation of cytolytic CD4 cells.
3) To investigate whether certain toll like receptor ligands (TLR), that activate DC differently,
have distinct effects on the generation of perforin mediated cytolytic activity by CD4 T cells.
In vivo studies: Past work has determined that CD4 T cells can promote survival against a highly lethal influenza virus, PR8, by both B cell dependent (antibodies) and B cell independent mechanisms (Brown, et al. 2006). The focus of this project will be to dissect the role of cytolytic CD4 cells in B cell independent protection against lethal influenza infection. Our hypothesis is that cytolytic CD4 cells can kill virally infected epithelial cells in the lung and contribute to viral clearance, even in the absence of B cells. Studies are underway to determine if CD4 cells directly interact with, and use perforin to kill, virally infected epithelial cells in vivo.
Vaccine studies: The long-term goal of the in vitro studies is to determine the factors that regulate cytolytic CD4 T cell development as a prerequisite to developing vaccine strategies that target these cells. By targeting cellular mechanisms of protection, new vaccines could be developed that provide universal protection against serologically distinct and emerging influenza viral strains. Future projects will use recombinant DNA technology, specifically plasmid DNA and commercially available vectors to produce different influenza proteins in bacteria or in eukaryotic cells. Recombinant proteins conjugated to various toll like receptor (TLR) activating adjuvants will be injected into normal mice to determine the activation of primary and memory CD4 T cell populations that are important in providing protection against pathogenic influenza infection.
Our lab is located in the Morrison Life Sciences Research Center as part of the Nebraska Center for Virology.
Current Lab Members: Back row: Tyler Moore, Jenna Canfield. Seated: Sarah Lee, Shirley Condon, Deb Brown. Not pictured: Alex Vogel.
- Moore, T. C., F. M. Al-Salleeh, D. M. Brown, and T. M. Petro. (2011) IRF3 Polymorphisms Induce Different Innate Anti-Viral Immune Responses in Macrophages. Virology, 418(1):40-8.
- Brown, D. M. 2010. Cytolytic CD4 Cells: Direct Mediators in Infectious Disease and Malignancy. Cell Immunol. 262:89-95.
- Brown, D. M., C. Kamperschroer, A. M. Dilzer, D. M. Roberts and S. L. Swain. 2009. IL-2 and Antigen Dose Differentially Regulate Perforin- and FasL-Mediated Cytolytic Activity in Antigen Specific CD4+ T Cells. Cell. Immunol. 257:69-79.
- Jelley-Gibbs D. M., J. P. Dibble, D. M. Brown, T. M. Strutt, K. K. McKinstry and S. L. Swain. 2007. Persistent depots of influenza antigen fail to induce a cytotoxic CD8 T cell response. J Immunol. 178(12):7563-70.
- Agrewala, J. N., D. M. Brown, N. M. Lepak, D. Duso, G. Huston and S. L. Swain 2007. Unique Ability of Activated CD4+ T Cells but Not Rested Effectors to Migrate to Nonlymphoid Sites in the Absence of Inflammation. J Biol Chem. Mar 2;282(9):6106-15. Epub 2006 Dec 29.
- Brown, D. M., A. M. Dilzer, D. L. Meents and S. L. Swain. 2006. CD4 T cell mediated protection from lethal influenza infection: perforin and antibody mediated mechanisms give a 1-2 punch. J Immunol, 177:2888-2898.
- Swain SL, Agrewala, JN, Brown DM, Jelley-Gibbs DM, Golech S, Huston G, Jones SC, Kamperschroer C, Lee W-H, McKinstry K, Roman E, Strutt T. and Weng N-P. 2006. CD4 Memory: Generation and Multi-faceted Roles for CD4 T Cells in Protective Immunity to Influenza. Immunological Reviews, 211:8-22
- Jelley-Gibbs, D.M., D.M. Brown, J.P. Dibble, L. Haynes, S.M. Eaton, and S.L. Swain. 2005. Unexpected prolonged presentation of influenza antigens promotes CD4 T cell memory generation. J Exp Med 202:697-706.
- Brown, D. M., E. Román and S. L. Swain. 2004. CD4 T cell responses to influenza infection. Seminars in Immunology, 16:171-177.