Impact of Aging on CD4 Immunity to Flu. We have defined extensive age-associated defects in immune system response particulariy in naive CD4 T cells that give poor effector responses and the generation of impaired memory cells. In the first funding cycle we found that pro-inflammatory cytokines (IL-1, IL-6 and TNFa) could reverse many of the defects in effector generation, and that surrogates of viral products that stimulate immune cells, called TLR agonists, induce production of these by DC presenting antigen to the T cells. We identified IL-6 production by DC during the cognate interaction as key for increasing expansion and blocking death of responding aged naive CD4 T cells. The activation also restores memory responses to some extent. Now we will define the molecular pathways leading to the "rescue" of the naTve CD4 T responses using a combination of reductionist in vitro approaches and carefully designed adoptive transfer models, that will allow us to determine the cellular and molecular mechanisms involved. We will use highly tractable TcR Tg models as well as polyclonal studies to dissect mechanisms. We will analyze rescue pathways in vivo as well as extend the studies to CDS T cells in mouse and to human CD4 and CDS T cells (part of Project 5). These studies will generate important information that could contribute to the development in future of better strategies, using TLR agonists, to more effectively vaccinate the elderiy and we expect to be able to develop a unified theory of how aging develops in T cells, what defects exist and which can be overcome and how in mice and man.
In the elderly, influenza results in high morbidity and mortality and current subunit vaccines are largely ineffective. Pandemic strains completely evade previous Ab-based immunity induced by current vaccines. Because their immune systems are defective and they respond to poorly to new infections, the elderly are at great risk. Our studies will evaluate whether TLR agonists, can overcome immune defects and may be combined with vaccines to give robust T cell immunity that will be broadly reactive to new strains.
|Lefebvre, Julie S; Lorenzo, Erica C; Masters, April R et al. (2016) Vaccine efficacy and T helper cell differentiation change with aging. Oncotarget 7:33581-94|
|Bartley, Jenna M; Pan, Sarah J; Keilich, Spencer R et al. (2016) Aging augments the impact of influenza respiratory tract infection on mobility impairments, muscle-localized inflammation, and muscle atrophy. Aging (Albany NY) 8:620-35|
|Lefebvre, Julie S; Masters, April R; Hopkins, Jacob W et al. (2016) Age-related impairment of humoral response to influenza is associated with changes in antigen specific T follicular helper cell responses. Sci Rep 6:25051|
|Zhou, Xin; Hopkins, Jacob W; Wang, Chongkai et al. (2016) IL-2 and IL-6 cooperate to enhance the generation of influenza-specific CD8 T cells responding to live influenza virus in aged mice and humans. Oncotarget 7:39171-39183|
|McElhaney, Janet E; Kuchel, George A; Zhou, Xin et al. (2016) T-Cell Immunity to Influenza in Older Adults: A Pathophysiological Framework for Development of More Effective Vaccines. Front Immunol 7:41|
|Yang, Rui; Lirussi, Dario; Thornton, Tina M et al. (2015) Mitochondrial CaÂ²âº and membrane potential, an alternative pathway for Interleukin 6 to regulate CD4 cell effector function. Elife 4:|
|Lanzer, Kathleen G; Johnson, Lawrence L; Woodland, David L et al. (2014) Impact of ageing on the response and repertoire of influenza virus-specific CD4 T cells. Immun Ageing 11:9|
|Zhang, Wenliang; Brahmakshatriya, Vinayak; Swain, Susan L (2014) CD4 T cell defects in the aged: causes, consequences and strategies to circumvent. Exp Gerontol 54:67-70|
|McKinstry, K Kai; Dutton, Richard W; Swain, Susan L et al. (2013) Memory CD4 T cell-mediated immunity against influenza A virus: more than a little helpful. Arch Immunol Ther Exp (Warsz) 61:341-53|
|Swain, Susan L; Blomberg, Bonnie B (2013) Immune senescence: new insights into defects but continued mystery of root causes. Curr Opin Immunol 25:495-7|
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