Our laboratory is interested in the immune response to viral infections, specifically focusing on the CD4+ T cell response to influenza. My post-doctoral studies at the Trudeau Institute determined that CD4 T cells contribute to clearance of highly pathogenic influenza virus by more direct mechanisms than has previously been appreciated. We have shown that CD4 cells acquire perforin mediated cytotoxicity that has historically been restricted to CD8+ killer cells. It is this unique characteristic of CD4 T cell function that forms the basis of our research program here at UNL. The overall goal of our research is to understand the innate signals that promote the differentiation of protective CD4 T cell responses to ultimately facilitate the design of new vaccine strategies against existing and emerging infectious diseases. Our research program is designed to answer the following questions:
- What are the cytokine and inflammatory signals that drive the differentiation of CD4 CTL in vivo in response to influenza infection?
- Do CD4 CTL represent a unique subset of CD4 T cell effectors?
- Can CD4 CTL be induced by vaccination and persist as memory cells?
- Do CD4 CTL act to decrease viral titers directly, or suppress macrophage inflammation at the site of infection?
We have developed unique in vitro and in vivo models to investigate the generation and regulation of cytolytic CD4 T cells (CD4 CTL) and have shown that IL-2 may be the master regulator of CD4 CTL differentiation. In vivo evidence also confirms that IL-2 signaling is necessary for GrB expression during influenza infection, but higher inflammatory responses provided by high dose infection overcomes the requirement for IL-2. We are actively pursuing the inflammatory mediators that may be responsible for driving cytolytic activity in CD4 T cells.
Influenza infection remains a serious health concern due to increased mortality and morbidity in infants, the elderly and immunocompromised individuals. In addition, recent outbreaks of antigenically distinct influenza strains have achieved pandemic status (2009 H1N1) and underscore the need for more effective vaccine strategies. Current vaccines induce high affinity antibodies that target the outer viral coat proteins: hemagglutinin (HA) and neuraminidase (NA), however, these proteins are the most susceptible to mutation and have been the driving force of pandemics in the last century. In contrast, T cells recognize the inner proteins of the virus such as nucleoprotein (NP) and acid polymerase (PA). These proteins are more conserved between different influenza strains and do not undergo mutation as readily. Therefore, there is much interest in developing vaccines that target conserved, internal proteins of influenza leading to cross protective, heterosubtypic T cell immunity. To that end, we have begun a new project to determine which innate immune pattern recognition receptors (PRRs) and cytokines are responsible for inducing CD4 CTL in vivo and whether vaccine strategies that target those receptors could induce CD4 CTL that contribute to protection. We are using an agonist (CpG) that activates TLR-9 as a vaccine strategy to induce T cell activation and memory formation that could ultimately provide protection against lethal infection. We have found that vaccination with CpG + inactivated virus significantly reduces viral titers and promotes survival (data not shown) upon challenge with lethal influenza infection. Immunization with low dose, live influenza infection serves as a positive control for clearance of virus and survival upon lethal challenge, while PBS and inactivated virus alone are negative controls showing high viral titers and mortality. Correlating with lower viral titers and survival is a robust T cell response to the lung upon lethal challenge. Both CD8 and CD4 T cells expressing GrB are at higher numbers in the lung after CpG vaccination and lethal challenge compared to vaccination with inactivated virus alone. Higher numbers of CD4 cells expressing IFN-g were also observed in mice receiving CpG vaccination compared to inactivated virus alone. These results suggest CpG vaccination induces T cell mediated immunity that provide protection against lethal influenza infection. Future studies will determine whether T cells are required for protection in our model.
- Vogel, A. J., S. Harris, N. Marsteller, S. Condon and D. M. Brown. 2014. Early cytokine dysregulation and viral replication contribute to mortality during lethal influenza infection. Viral Immunology, 27(5):214-24. doi: 10.1089/vim.2013.0095. Epub 2014 May 1. PMC4043423
- Workman, A., A. Jacobs, A. J. Vogel, S. Condon and D. M. Brown. 2014. Inflammation enhances IL-2 driven differentiation of cytolytic CD4 cells. PLoS One 9(2): e89010. doi:10.1371/journal.pone.0089010. PMC3930678
- Moore, T. C. P. M. Kumm, D. M. Brown and T. M. Petro. 2014. Interferon Response Factor 3 is crucial to poly-I:C induced NK cell activity and control of B16 melanoma growth. Cancer Lett, 346 (1):122-8. PMC3963264
- Moore, T. C. P. M. Kumm, D. M. Brown and T. M. Petro. 2013. Interferon Response Factor 3 is crucial to poly-I:C induced NK cell activity and control of B16 melanoma growth. Cancer Lett, epub ahead of print.
- Moore, T. C., L. Cody, P. M. Kumm, D. M. Brown and T. M. Petro. 2013. IRF3 helps control acute TMEV infection through IL-6 expression but contributes to acute hippocampus damage following TMEV infection. Virus Research, 178(2):226-33.
- Moore, T. C., K. Bush, E. Cody, D. M. Brown and T. M. Petro. 2012. Interleukin-6 control of early Theiler's Murine Encephalomyelitis Virus replication in macrophages occurs in conjunction with STAT1 activation and nitric oxide production. J Virology, 86:10841-51.
- Gangaplara A., C. Massilamany, D. M. Brown, G. Delhon, A. K. Pattnaik, N. Chapman, N. Rose, D. Steffen and J. Reddy. 2012. Coxsackievirus B3 infection leads to the generation of cardiac myosin heavy chain-α-reactive CD4 T cells in A/J mice. Clin Immunol. 144(3):237-49.
- McKinstry, K. K., T. M. Strutt, Y. Kuang, D. M. Brown, S. Sell, R. W. Dutton and S. L. Swain. 2012. Memory CD4+ T-cells protect against influenza by multiple synergizing mechanisms J Clin Invest, 122:2847-56.
- Brown, D. M., S. Lee, M. L. Garcia-Hernandez, and S. L. Swain. 2012. Multi-functional CD4 cells expressing IFN-g and perforin mediate protection against lethal influenza infection. J Virology 86:6792-803.
- 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 Non-lymphoid 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.
- Crowe, S.R., S.C. Miller, D.M. Brown, P.S. Adams, R.W. Dutton, A.G. Harmsen, F.E. Lund, T.D. Randall, S.L. Swain, and D.L. Woodland. 2006. Uneven distribution of MHC class II epitopes within the influenza virus. Vaccine 24:457-467.
- 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.
- Powell, T. J., D. M. Brown, J. Hollenbaugh, R. A. Kemp, T. Charbonneau, S. L. Swain and R. W. Dutton. 2004. CD8+ T cells responding to influenza infection reach and persist at higher numbers than CD4+ T cells independently of precursor frequency. J. Clin. Immunol. 113, 89-100.
- Swain, S.L., J.N. Agrewala, D. M. Brown, and E. Roman. 2002. Regulation of Memory CD4 T Cells: Generation, Localization and Persistence. In Lymphocyte Activation and Immune Regulation IX – Homeostasis Lymphocyte Traffic. S. Gupta, E. Butcher and W. Paul, editors. Kluwer Academic/Plenum Publishers, New York, NY. 113-120.
- Fisher, T. L., M. Nocera, R. A. Willis, M. J. Turner, C. S. Abdul Alim, D. M. Brown, P. A. Bourne, P. A. di Sant’ Agnese, E. M. Messing, E. M. Lord, and J. G. Frelinger. 2001. Generation of Monoclonal Antibodies Specific for Human Glandular Kallikrein (hK2) Using hK2-Expressing Tumors. Prostate. 51:153.
- Gerber, S., C. Lane, D. M. Brown, E. M. Lord, M. Lorenzo, J. D. Clements, E. Rybicki, A-L Williamson and R. C. Rose. 2001. Human papilloma virus-like particles are efficient oral immunogens when co-administered with Escherichia coli heat-labile enterotoxin mutant R192G or CpG DNA. J. Virology 75:4752.
- Brown, D. M., T. L. Fisher, C. Wei, J. G. Frelinger and E. M. Lord. 2001. Tumours can act as adjuvants for humoral immunity. Immunology 102:486.