Regulation of phagosomal maturation in dendritic cells upon TLR stimulation

ALLOATTI, ANDRÉS; HOFFMANN, EIK; KOTSIAS, FIORELLA; SAN ROMAN, MABEL; VARGAS, PABLO; AMIGORENA, SEBASTIAN

Tours, Val de Loire

Congreso; 13th International Symposium on Dendritic Cells; 2014

Institute Curie, INRA, CIML

In DCs, stimulation of particular Toll-like receptors (TLRs) can influence the rate of phagosome fusion with lysosomes, thereby modulating both antigen degradation and presentation. We show here, that in bone marrow-derived DCs, stimulation of TLR4 by lipopolysaccharide (LPS) delays fusion between phagosomes and lysosomes by a yet unknown mechanism. Using ovalbumin-conjugated beads as a model system, we applied video microscopy as well as ultra-structural approaches and showed that pre-treatment of cells with LPS leads to clustering of lysosomes in the peri-nuclear region in a subpopulation of DCs. These cells displayed strongly reduced phago-lysosomal fusion activity measured by flow cytometry-based single organelle analysis. In addition, stimulation of TLR4 also increased cross-presentation of both bead-bound and soluble antigens to antigen-specific T lymphocytes.