Abstract: 【Abstract】 Objective To evaluate the effect of Candida albicans （C. albicans） hyphae on autophagic flux in murine bone marrow-derived macrophages （BMDM）. Methods BMDM were in vitro stimulated with C. albicans hyphae for 0.5, 4 and 12 hours, and the 0-hour group treated without hyphae served as a control. Western blot analysis was performed to detect the conversion of microtubule-associated protein 1 light chain 3 （LC3）-Ⅰto LC3-Ⅱ, and determine the expression of phosphorylated mechanistic target of rapamycin （p-mTOR） at each time point. Some BMDM were divided into several groups: control group receiving no treatment, hyphae group treated with C. albicans hyphae, lysosomal inhibitor groups treated with different lysosomal inhibitors, including E-64d （a cysteine proteinase inhibitor） + pepstatin （a pepsin inhibitor）, bafilomycin-A1 （BAF-A1）, ammonium chloride and chloroquine, and hyphae combined with lysosomal inhibitor groups treated with lysosomal inhibitors immediately followed by C. albicans hyphae. After 4- or 12-hour treatment, the effect of C. albicans hyphae on basal autophagic flux in murine BMDM was evaluated. Statistical analysis was carried out by using unpaired t test, factorial design analysis of variance and least significant difference-t test. Results After 0.5-, 4- and 12-hour in vitro treatment with C. albicans hyphae, the conversion of LC3-Ⅰto LC3-Ⅱ significantly increased in murine BMDM （1.254 ± 0.118, 1.629 ± 0.391, 1.598 ± 0.379, respectively） compared with the 0-hour group （0.983 ± 0.030; t = 3.875, 2.856, 2.804, respectively, all P < 0.05）, while there was no significant difference in the protein expression of p-mTOR among the 0-, 0.5-, 4- and 12-hour groups. After 4- and 12-hour in vitro treatment with C. albicans hyphae combined with lysosomal inhibitors E-64d and pepstatin, the accumulation level of LC3-Ⅱ significantly increased in BMDM compared with those treated with E-64d and pepstatin alone （t = 3.691, 6.648, respectively, both P < 0.05）. Compared with the corresponding lysosomal inhibitor groups, the accumulation level of LC3-Ⅱsignificantly increased in BMDM treated with C. albicans hyphae combined with BAF-A1, ammonium chloride or chloroquine for 4 and 12 hours（all P < 0.05）. Conclusion In vitro treatment with C. albicans hyphae can increase the conversion of LC3-Ⅰto LC3-Ⅱ in the basal autophagic flux in murine BMDM.

Key words: Candida albicans, Hyphae, Macrophages, Autophagy, Microtubule-associated proteins