Activation of natural killer T cells by alpha-galactosylceramide mediates clearance of bacteria in murine urinary tract infection.
OBJECTIVE
alpha-Galactosylceramide (alpha-GalCer), which is a specific ligand for CD1d restricted variable-alpha14chain natural killer T cells, has an important role in host defense against a range of microbial infections. We examined whether alpha-GalCer mediates bacterial clearance in a murine urinary tract infection (UTI) model.


METHODS
The murine UTI model was established by intravesical inoculation of Escherichia coli, Pseudomonas aeruginosa or methicillin resistant Staphylococcus aureus, followed by clamping the distal end of the urethra of C57BL/6 female mice for 4 hours. The antibacterial effect of alpha-GalCer was assessed by comparing the number of cfu/gm kidney tissue 4 days after bacterial inoculation. The prophylactic effect of alpha-GalCer was examined by administrating 3 doses of intraperitoneal alpha-GalCer on alternate days 24 hours before E. coli inoculation. The therapeutic effect of alpha-GalCer was tested by the administration of 2 doses of intraperitoneal alpha-GalCer after bacterial inoculation. To assess cytokine induction by alpha-GalCer serum levels of interleukin-12, interferon-gamma and tumor necrosis factor-alpha were measured by cytometric bead array assay.


RESULTS
When administered before bacterial inoculation, alpha-GalCer showed a strong prophylactic antibacterial effect. alpha-GalCer also showed a marked antibacterial effect on preestablished mice UTI caused by E. coli, P. aeruginosa and methicillin resistant S. aureus. alpha-GalCer induced a significantly higher level of interleukin-12, interferon-gamma and tumor necrosis factor-alpha compared with control glycolipids.


CONCLUSIONS
These findings suggest a significant role for alpha-GalCer in regulating antibacterial functions by activating natural killer T cells in the murine UTI model.
Minagawa
Shingo
S
Department of Urology, Akita University School of Medicine, Akita and Hirosaki University School of Medicine, Hirosaki, Japan.
Ohyama
Chikara
C
Hatakeyama
Shingo
S
Tsuchiya
Norihiko
N
Kato
Tetsuro
T
Habuchi
Tomonori
T
D000818:Animals; D016207:Cytokines / Q000097:blood; D004195:Disease Models, Animal; D004927:Escherichia coli Infections / Q000276:immunology*; D005260:Female; D005699:Galactosylceramides / Q000502:physiology*; D007694:Killer Cells, Natural / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D011552:Pseudomonas Infections / Q000276:immunology*; D013203:Staphylococcal Infections / Q000276:immunology*; D014552:Urinary Tract Infections / Q000276:immunology*
D016207:Cytokines; D005699:Galactosylceramides; C493154:alpha-galactosylceramide