POLARIZING T CELL RESPONSES IN VIVO WITH DENDRITIC CELLS

Emory University, Atlanta GA

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Abstract

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Last year, we defined a novel mechanism by which DCs can be programmed to induce T regulatory cells. Essentially, we demonstrated that TLR2 signaling induced splenic DCs to express the retinoic acid metabolizing enzyme retinaldehyde dehydrogenase type 2 and interleukin-10 (IL-10) and to metabolize vitamin A and stimulate Foxp3(+) T regulatory cells (T(reg) cells). Retinoic acid acted on DCs to induce suppressor of cytokine signaling-3 expression, which suppressed activation of p38 mitogen-activated protein kinase and proinflammatory cytokines. Consistent with this finding, TLR2 signaling induced T(reg) cells and suppressed IL-23 and T helper type 17 (T(H)17) and T(H)1-mediated autoimmune responses in vivo. In contrast, dectin-1 signaling mostly induced IL-23 and proinflammatory cytokines and augmented T(H)17 and T(H)1-mediated autoimmune responses in vivo. These data define a new mechanism for the systemic induction of retinoic acid and immune suppression against autoimmunity, and were published in Nature Medicine. In addition to this work, we performed a microarray analysis of splenic DCs that were cultured in vitro with zymosan or other TLR ligands, to assess the transcriptional profiles induced. Our goal is to use this approach to identify novel genes that program DC differentiation and modulate the Th1/Th2/Th17/T regulatory balance.