Objective To investigate the
roles of Dectin-1 in
phagocytosis of
Candida albicans (C.albicans) by
macrophage-like
cells derived from a
human acute monocytic leukemia cell line THP-1.
Methods THP-1
macrophage-like
cells served as the target
cells,and were transfected with
small interfering RNA (
siRNA) targeting Dectin-1 to down-regulate the expression of Dectin-1 receptor (
siRNA-Dectin-1 group).THP-1
macrophage-like
cells transfected with nonsense
siRNA (
siRNA-NC) served as a negative
control group.After
transfection,the THP-1
macrophage-like
cells in the above 2 groups were cocultured with
heat-killed C.albicans separately.And then,
fluorescence microscopy was performed to count THP-1
macrophage-like
cells phagocytosing C.albicans,and
flow cytometry was used to determine the mean
fluorescence intensity (MFI) of dihydrorhodamine (DHR)-123 fluorescent
cells.
Statistical analysis was done by one-way
analysis of variance (
ANOVA) and t test with the SPSS19.0
software.Results After
transfection with
siRNA-Dectin-1,the
mRNA and
protein expression of Dectin-1 significantly decreased in THP-1
macrophage-like
cells (t =26.163,P < 0.001).After 1-,2-,4-hour
co-culture of THP-1 macrophagelike
cells with C.albicans,
fluorescence microscopy showed that the
phagocytosis rates of C.albicans by THP -1
macrophage-like
cells were significantly lower in the
siRNA-Dectin-1 group than in the negative
control group (17.5% vs.22.1%,18.6% vs.24.3%,39.2% vs.59.1%,respectively,all P < 0.05),so were the percentage of THP-1
macrophage-like
cells phagocytosing more than 3 C.albicans
cells (2.2% vs.4.7%,2.5% vs.5.4%,5.1% vs.8.3%,respectively,all P < 0.05).After 30-minute,1-,2-and 4-hour
co-culture of THP-1
macrophage-like
cells with DHR-123-labelled C.albicans,
flow cytometry showed that the MFI of C.albicans-phagocytosing
cells was significantly lower in the
siRNA-Dectin-1 group than in the negative
control group (36.8 vs.45.7,54.3 vs.62.4,72.1 vs.84.9,93.6 vs.116.7,respectively,all P < 0.05).Conclusion Dectin-1 receptor
plays an important
role in the
phagocytosis of C.albicans by
macrophages.