Non-pathogenic Mycobacterium smegmatis induces the differentiation of human monocytes directly into fully mature dendritic cells.
Mycobacterium smegmatis infects human monocytes that can be precursors of dendritic cells. We tested whether the interaction of M. smegmatis with monocytes modulated their differentiation into dendritic cells. We found that M. smegmatis-infected monocytes differentiated into CD1a-CCR7+ dendritic cells in the presence of GM-CSF and IL-4 and acquired a mature phenotype since they expressed CD83 molecules in the absence of maturation stimuli. Dendritic cells derived from M. smegmatis-infected monocytes stimulated with bacterial products, produced IL-10 and still retained the capacity to produce IL-12. Consequently, they polarized naïve T lymphocytes towards a mixed Th1/Th2 immune response inducing both IFN-gamma and IL-4 production. These findings suggest that the exposure to environmental mycobacteria could modulate the differentiation of dendritic cells making them able to migrate into secondary lymphoid organs and modulate the adaptive immune response. This could explain one of the mechanisms by which environmental mycobacteria can influence the immune response to pathogenic species.
Martino
Angelo
A
National Institute for Infectious Diseases Lazzaro Spallanzani, Rome, Italy.
Sacchi
Alessandra
A
Volpe
Elisabetta
E
Agrati
Chiara
C
De Santis
Rafaella
R
Pucillo
Leopoldo Paolo
LP
Colizzi
Vittorio
V
Vendetti
Silvia
S
D000293:Adolescent; D000328:Adult; D002450:Cell Communication / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology* / Q000276:immunology / Q000382:microbiology*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology / Q000382:microbiology; D006801:Humans; D016753:Interleukin-10 / Q000096:biosynthesis; D018664:Interleukin-12 / Q000096:biosynthesis; D009000:Monocytes / Q000166:cytology* / Q000276:immunology / Q000382:microbiology*; D020102:Mycobacterium smegmatis / Q000276:immunology*; D013601:T-Lymphocytes / Q000378:metabolism; D018417:Th1 Cells / Q000166:cytology / Q000276:immunology / Q000382:microbiology; D018418:Th2 Cells / Q000166:cytology / Q000276:immunology / Q000382:microbiology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D018664:Interleukin-12