Roles of Dectin-1 in phagocytosis of Candida albicans by macrophage-like cells derived from a human acute monocytic leukemia cell line THP-1 / 中华皮肤科杂志

ABSTRACT

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.