51. Role of the chemokines CCL17 and CCL22 in bacterial infection and IL-33-induced immune responses
- Author
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Thiem, Manja Wibke and Thiem, Manja Wibke
- Abstract
The chemokines CCL17 and CCL22 are primarily expressed by dendritic cells (DC) and macrophages. Both chemokines share the receptor CCR4, which is expressed on DC and macrophages as well as on a variety of different T cell subsets, including Th1 cells, Th2 cells, and regulatory T (Treg) cells. As ligands of CCR4, CCL17 and CCL22 recruit T cells, facilitate the T cell-DC interaction, and sensitise DC for migration. However, CCL17 and CCL22 differ in their distinct signaling pathways and functions, a phenomenon that has been termed biased agonism. CCL17 is involved in the induction and enhancement of numerous allergic and inflammatory diseases. In contrast, CCL22 is rather associated with an immunosuppressive environment. Moreover, CCL17 induces migration and activation of Th1 and Th2 cells as well as sensitising DC migration towards CCR7-ligands, whereas CCL22 facilitates the recruitment of Treg cells. In addition, CCL22 shows higher receptor-binding affinity and induces desensitisation and internalisation of CCR4 more rapidly than CCL17. Although CCL17 and CCL22 were extensively studied in allergic, inflammatory, and autoimmune diseases as well as in the tumor microenvironment, their involvement in infectious diseases has not been well described. Furthermore, IL-33 stimulates the production of CCL17 and CCL22 by DC. In the context of Salmonella infection, IL-33 can be produced by intestinal stroma cells after stimulation with bacterial ligands and IL-33 secretion by pericryptal fibroblasts was shown to be directly protective against the infection. Hence, the aim of this thesis was to elucidate the differential function of CCL17 and CCL22 in the context of Salmonella infection and IL-33-mediated immune responses in organs linked to Salmonella dissemination and beyond. Using a vaccination/challenge Salmonella mouse model, wt, CCL17E/E CCL22-/-, and CCR4-/- mice were investigated for their antigen-specific CD4+ T cell response. Vaccinated CCL17E/E CCL22-/- and CCR4-/- m
- Published
- 2023