Plasma membrane proteomes of differentially matured dendritic cells identified by LC–MS/MS combined with iTRAQ labelling
Résumé
Dendritic cells (DCs) play a pivotal role in polarising Th lymphocyte subsets but it is unclear
whatmolecular events occur when DCs generate Th2-type responses. Here, we analysed plasma
membrane-enriched fractions from immature, pro-Th1 and pro-Th2 DCs and used a combination
of iTRAQ labelling and LC–MS/MS to quantify changes in the proteomes. Analysiswas
performed on triplicate biological samples and changes verified by flow cytometry. MHC class
II molecules and CD29 were up-regulated in pro-Th1 DCs whilst CD18 and CD44 were upregulated
in pro-Th2 DCs. One of the most down-regulated molecules in pro-Th1 DCs was
YM-1 whilst the greatest decrease in pro-Th2 DCs was NAP-22. Other molecules upregulated
in pro-Th2 DC compared to pro-Th1 DCs included some potentially involved in
protein folding during antigen processing (clathrin and Rab-7), whilst other non-membrane
proteins such as enzymes/transporters related to cellmetabolism(malate dehydrogenase, pyruvate
kinase, and ATPase Na+/K+) were also recorded. This suggests that pro-Th2 DCs are
more metabolically activewhile pro-Th1 DCs have amature ‘end state’. Overall, althoughseveralmoleculeswere
preferentially expressed on pro-Th2 DCs, our proteomics data support the
view of a ‘limited maturation’ of pro-Th2 DCs compared to pro-Th1 DCs.