Project description:Inducing the long-term protection via effector memory CD8+ T cells residing in the peripheral tissues is the ultimate goal of T cell-based vaccination strategies. CD8+ T cell reacting against a particular set of antigenic peptides show propensity to generate stable pools of memory inflating cells with profound protective capacity. While the epitopes that induce memory inflation have been thoroughly characterized and used as excellent constituents of vaccines such as recombinant adenoviruses, the identity of the tissue factors responsible for maintaining memory inflating CD8+ T cells remains elusive. Here, we have used a Cre recombinase-dependent, -galactosidase (gal)–recombinant adenovirus vector that allowed for cell-specific expression of gal epitopes and identification of cell types involved in generation of inflationary responses. While targeting antigen expression to classical hematopoietic antigen presenting cells was insufficient to activate gal-specific CD8+ T cells, expressing the antigen exclusively in CCL19-producing fibroblastic stromal cells (FSCs) induced robust anti-gal CD8+ T cell response. Using bone marrow chimera mice to abolish the expression of major histocompatibility complex I (MHC-I) and Basic Leucine Zipper ATF-Like Transcription Factor 3 (BATF3) in hematopoietic cells we demonstrated that CCL19-expressing FCS function as antigen libraries, gradually releasing the antigen to CD103+ DCs to maintain gal-specific memory inflating population. Moreover, targeted ablation of CCL19-producing cells revealed that pulmonary fibroblastic stromal cells act as the principal organizer of the nurturing niches that support the metabolic conversion in CD8+ T cells necessary for the generation of long-lasting protective inflationary responses. Overall, our data reveal a hitherto unknown function of CCL19-expressiong fibroblastic stromal in supporting the metabolic fitness of CD8+ T cells, thereby promoting the generation of tissue-specific and long-lasting protective CD8+ T cell responses.

Project description:Many aged individuals develop monoclonal expansions of CD8 T cells. These expansions are derived from a CD8 memory T cell that outcompetes neighboring CD8 T cells. The molecular alterations within clonal expansions that confer this competitive advantage relative to other CD8 T cells remains unknown. These microarray experiments were designed to identify genes differentially expressed in age-associated expansions of CD8 memory T cells relative to polyclonal CD8 memory T cells found in the same aged mice. Subsequent analysis of these data identified two major types of clonal expansions, distinguished by expression level of integrin a4 mRNA and protein. Based on this classification, Expansion_rep1 belongs to the integrin a4 high subtype of clonal expansions. In contrast, reps 2, 4, and 5 belong to the integrin a4 low subtype of clonal expansions. Given the divergent biological properties of these two subtypes of clonal expansions, we have focused genes differentially expressed between Expansion_rep 2, 4, and 5 and their paired PolyclonalAged samples. Experiment Overall Design: A total of 8 samples were analyzed for gene expression using the Affymetrix mouse genome 430 2.0 microarray platform. The experimental samples of interest were age-associated clonal expansions of CD8 memory T cells. We purified four clonal expansions from four independent, aged mice (indicated as "Expansion" rep1 2, 3, 4). For each clonal expansion of CD8 memory T cells that was purified, there was a paired control in which polyclonal CD8 memory T cells were harvested from the same aged mouse (denoted as "PolyclonalAged" rep1, 2, 3, 4). These paired samples allow one to consider gene expression changes from mice which have undergone the same age-associated changes in biology. The predominant comparison this study focused on was changes in gene expression between age-associated clonal expansions of CD8 memory T cells and their paired, polyclonal CD8 memory T cells. A total of 4 of these pairs were collected.

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Memory CD8+ T cells mediate early pathogen-specific protection through localized delivery of antigen-dependent chemokines and IFNgamma to clusters of inflammatory monocytes

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