S layer protein A of Lactobacillus acidophilus NCFM regulates immature dendritic cell and T cell functions.
Dendritic cells (DCs) are antigen-presenting cells that play an essential role in mucosal tolerance. They regularly encounter beneficial intestinal bacteria, but the nature of these cellular contacts and the immune responses elicited by the bacteria are not entirely elucidated. Here, we examined the interactions of Lactobacillus acidophilus NCFM and its cell surface compounds with DCs. L. acidophilus NCFM attached to DCs and induced a concentration-dependent production of IL-10, and low IL-12p70. We further demonstrated that the bacterium binds to DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN), a DC- specific receptor. To identify the DC-SIGN ligand present on the bacterium, we took advantage of a generated array of L. acidophilus NCFM mutants. A knockout mutant of L. acidophilus NCFM lacking the surface (S) layer A protein (SlpA) was significantly reduced in binding to DC-SIGN. This mutant incurred a chromosomal inversion leading to dominant expression of a second S layer protein, SlpB. In the SlpB-dominant strain, the nature of the interaction of this bacterium with DCs changed dramatically. Higher concentrations of proinflammatory cytokines such as IL-12p70, TNFalpha, and IL-1beta were produced by DCs interacting with the SlpB-dominant strain compared with the parent NCFM strain. Unlike the SlpA-knockout mutant, T cells primed with L. acidophilus NCFM stimulated DCs produced more IL-4. The SlpA-DC-SIGN interaction was further confirmed as purified SlpA protein ligated directly to the DC-SIGN. In conclusion, the major S layer protein, SlpA, of L. acidophilus NCFM is the first probiotic bacterial DC-SIGN ligand identified that is functionally involved in the modulation of DCs and T cells functions.
Konstantinov
Sergey R
SR
Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands.
Smidt
Hauke
H
de Vos
Willem M
WM
Bruijns
Sven C M
SC
Singh
Satwinder Kaur
SK
Valence
Florence
F
Molle
Daniel
D
Lortal
Sylvie
S
Altermann
Eric
E
Klaenhammer
Todd R
TR
van Kooyk
Yvette
Y
D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D002454:Cell Differentiation / Q000276:immunology; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology* / Q000382:microbiology*; D007108:Immune Tolerance / Q000276:immunology; D007668:Kidney / Q000166:cytology; D007779:Lactobacillus acidophilus / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D008264:Macrophages / Q000276:immunology / Q000382:microbiology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D016296:Mutagenesis; D019936:Probiotics; D013601:T-Lymphocytes / Q000276:immunology* / Q000382:microbiology*; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D001426:Bacterial Proteins; D016207:Cytokines; D008562:Membrane Glycoproteins; C055764:S-layer proteins; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; C070683:surface layer protein A, Bacteria