Poster Presentation 18th International Symposium on Dendritic Cells 2026

Dissecting subset-specific activation programmes of skin migratory type 2 dendritic cells (#150)

Olivier Lamiable 1 , Shiau Choot Tang 1 , Sam Old 1 , David Eccles 1 , Claire Harlick 1 , Marie-Sophie Fabre 1 , Franca Ronchese 1
  1. Malaghan Institute of Medical Research, Wellington, WELLINGTON, New Zealand

DC function is determined by ontogeny and tissue environment, which together shape how DCs sense threats, migrate, and engage T cells in draining lymph nodes. Disentangling these contributions to DC transcriptional responses remains challenging. In healthy skin, homeostatic IL-13 from dermal ILC2s drives the differentiation of a CD11blo DC2 subset specialised for Th2 priming, while CD11bhi DC2s instruct Th1 and Th17 responses. Studying the transcriptional responses of skin DC2s allows us to dissect this interplay.

We performed bulk RNA-seq on antigen-positive and antigen-negative migratory CD11bhi and CD11blo DC2s sorted from skin draining lymph nodes at peak antigen capture after immunisation with fluorescently labelled pathogens driving Th1, Th2 or Th17 responses. Compared to their antigen-negative counterparts, antigen-positive DC2s of both subsets displayed an activation programme enriched for NF-κB, IRF and STAT target genes. qPCR validation in anti-CD4 antibody treated mice showed that a subset of these genes required T cell contact. CD11blo cells additionally expressed lower levels of TLRs, IFN-γ signalling including Ifngr1, and inflammasome genes, and failed to upregulate Th1 and Th17 polarising cytokines.

To test whether IL-13 directly drives this repression, we performed bulk RNA-seq on Flt3L BMDCs treated for 3 days from day 6 with recombinant IL-13. The in vitro programme recapitulated the reduction of TLRs, inflammasome genes and Ifngr1 observed in CD11blo DC2s in vivo.

We next assessed the consequences of losing IL-13 conditioning by performing scRNA-seq on DC2s from IL-4Rα deficient mice, which cannot respond to IL-4 or IL-13 and lack CD11blo DC2s. Following Th2 immunisation, an antigen-positive CD11bhi cluster accumulated in these animals and showed reduced Cd40 expression and NF-κB activity. Antigen uptake without IL-13 conditioning therefore produces CD11bhi DC2s with reduced markers of T cell engagement during Th2 immunisations.

Together, these data describe IL-13-dependent and T cell-dependent contributions to skin DC2 activation.