Fonsecaea pedrosoi-induced Th17-cell differentiation in mice is fostered by Dectin-2 and suppressed by Mincle recognition.
Bottom Line: Here, we investigated whether costimulation by TLR agonists fosters the development of adaptive immune responses, by examining the development of fungus-specific T cells.Subcutaneous infection of mice with F. pedrosoi spores induced the activation, expansion, and differentiation of Ag-specific CD4(+) T cells but TLR costimulation did not further augment these T-cell responses.The Dectin-2/FcRγ/Card9 signaling pathway promoted the differentiation of fungus-specific CD4(+) T cells into Th17 cells, whereas Mincle inhibited the development of this T-helper subset in infected mice.
Affiliation: Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, WI, USA.Show MeSH
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Mentions: Cell‐mediated immune responses to chromoblastomycosis are poorly described. Studies in athymic nude and CD4−/− mice showed poor granuloma formation, increased fungal loads and decreased DTH and IFN‐γ production supporting a role for T‐cell immune responses 10, 12. To investigate whether subcutaneous injection of F. pedrosoi spores activates and expands antigen‐specific CD4+ T cells we used TCR transgenic (Tg) 1807 cells that recognize systemic dimorphic fungi 13 and can also be activated by F. pedrosoi11. We first optimized the experimental conditions to achieve increased expansion of activated 1807 cells in F. pedrosoi infected versus uninfected controls. Previously, we only saw about a twofold increase in the number of CD44+ 1807 cells for the above‐mentioned comparison 11. We reduced the number of adoptively transferred naïve 1807 cells from one million 11 to 105 and used either two million or two hundred million spores for the footpad injections. Adoptive transfer of lower numbers of naive 1807 cells prior to infection increased the number of activated (CD44+), IL‐17 and IFN‐γ producing 1807 CD4+ T cells >20‐fold in mice infected with 2 million spores versus naïve mice (Fig. 1A–C). Thus, F. pedrosoi infection induced the generation of Ag‐specific Th17 and Th1 CD4+ T cells that can be tracked with adoptively transferred 1807 cells.
Affiliation: Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, WI, USA.