ABSTRACT
Objective:To investigate the physiological role of F1Fo-ATP synthase α-subunit encoding gene (ATP1) in promoting Candida albicans ( C. albicans) to escape from macrophage killing through eliminating intracellular reactive oxygen species (ROS) by using a reverse genetics approach. Methods:An ATP1 deletion strain and a parental strain of C. albicans were cultured on the YPD media, and the number of formed colonies on the plates was counted to evaluate in vitro viability of C. albicans. To evaluate their in vivo viability, the ATP1 deletion strain and parental strain of C. albicans were inoculated into mice through the caudal vein, kidney tissues were taken out from the mice 1-7 days after the infection, and inoculated onto the YPD medium followed by numeration of colonies after 48 hours of culture. After co-culture of overnight-cultured C. albicans suspensions with macrophages, some of the C. albicans suspensions were inoculated onto the YPD solid medium followed by numeration of colonies and determination of survival rate, and some culture supernatants were inoculated into the 96-well plate for detection of the level of lactate dehydrogenase (LDH) released by macrophages by LDH release assay. A model mimicking oxidative stress in macrophages was established by using hydrogen peroxide. After treatment with hydrogen peroxide, the number of colonies was counted to compare the viability of the C. albicans strains. DCFH-DA staining was conducted to detect the intracellular ROS level in C. albicans after co-culture with macrophages or treatment with hydrogen peroxide, and real-time fluorescence-based quantitative PCR to measure mRNA expression of catalase 1 (CAT1) , superoxide dismutase 4 (SOD4) and SOD5 genes in C. albicans after treatment with hydrogen peroxide. Statistical analysis was carried out by using two-way analysis of variance or Student t test. Results:In vitro, the colony number in both the parental strain group and ATP1 deletion strain group gradually increased over time; after 24 hours, the colony number of the ATP1 deletion strain group was only 10% of that in the parental strain group ( F = 481.84, P < 0.001) . The number of colony formed by the parental strain-infected mouse kidney tissues gradually increased over time, but that by the ATP1 deletion strain-infected mouse kidney tissues gradually decreased, and there was a significant difference between the two groups ( F = 78.27, P = 0.001) . After in vitro co-culture of C. albicans with macrophages, the survival rate in the ATP1 deletion strain group (62.67% ± 3.51%) was significantly lower than that in the parental strain group (82.33% ± 2.52%, t = 7.88, P = 0.001) , and the percentage of LDH released by macrophages was also significantly lower in the ATP1 deletion strain group (27.80% ± 3.54%) than in the parental strain group (87.78% ± 0.17%, t = 33.89, P < 0.001) , which were consistent with the in vivo results. In the model mimicking oxidative stress, the viability of the ATP1 deletion strain group was significantly lower than that of the parental strain group ( F = 3 440.65, P < 0.001) . Both in the co-culture model with macrophages and in the model mimicking oxidative stress in macrophages, the intracellular ROS levels were significantly higher in the ATP1 deletion strain group than in the parental strain group (both P < 0.001) . Furthermore, the mRNA expression of CAT1, SOD4 and SOD5 genes was significantly lower in the ATP1 deletion strain group than in the parental strain group after treatment with hydrogen peroxide (all P < 0.001) . Conclusion:ATP1 deletion may reduce the capabilities of C. albicans to counteract oxidative stress and eliminate ROS, likely by down-regulating the expression of oxidative stress- and ROS clearance-related genes respectively, which may prevent C. albicans from escaping from the macrophage killing and lead it to be eliminated by the host ultimately.
ABSTRACT
Objective To evaluate the in vitro synergistic effect of tetrandrine on ketoconazole against Candida parapsilosis complex.Methods According to the Clinical and Laboratory Standards Institute (CLSI) M27-A3 guidelines,the microdilution checkerboard method was used to evaluate in vitro antifungal activities of ketoconazole alone and in combination with tetrandrine against 21 clinical isolates of Candida parapsilosis complex based on the fractional inhibitory concentration index (FICI).Antifungal effects of the above drugs at different time points were evaluated by the XTT assay,and then time-killing curves were drawn and assessed to investigate the in vitro dynamic antifungal activity.Results The minimum inhibitory concentrations (MICs) of tetrandrine and ketoconazole alone against 21 clinical isolates of Candida parapsilosis complex were 32-64 mg/L and 0.031 25-2 mg/L,respectively.When ketoconazole was combined with tetrandrine,MICs of tetrandrine and ketoconazole were reduced to 2-8 mg/L and 0.008-0.25 mg/L respectively,and the FICI ranged from 0.09 to 0.5.The time-killing curves revealed that the fungal growth was delayed obviously in the combination group compared with the ketoconazole alone group and tetrandrine alone group.Conclusion Tetrandrine has obvious synergistic effects on ketoconazole against Candida parapsilosis complex in vitro.
ABSTRACT
To investigate the effect of CDR1/CDR2 or MDR1 genes overexpression on oxidative stress in Candida albicans,we evaluated the effect of H2O2 on cell viability in C.albicans overexpressing genes CDR1 /CDR2 or MDR1 and their parent strains.After establishing an oxidative stress model with H2O2,we detected reactive oxygen species (ROS),mitochondrial membrane potential (Δψm) and the expression of oxidative stress response-related genes (CAP1 and GRP2) and ROS clearance related-genes (SOD2 and SOD5).The results showed that C.albicans growth were inhibited by 100％ after the treatment of 5 mmol/L H2O2.HeO2 caused more ROS accumulation and Δψm reduction in parent strains than in CDR1/CDR2 or MDR1 genes overexpressed strains (P＜0.05).Compared to parent strains,the up-regulated expression of CAP1 and GRP2 were relatively less in CDR1/CDR2 or MDR1 genes overexpressed strains,moreover,the down-regulated expression of SOD2 and SOD5 were also relatively less in CDR1/CDR2 or MDR1 genes overexpressed strains (P＜0.05).In conclusion,the overexpression of CDR1/CDR2 and MDR1 genes could reduce the oxidative stress response and enhance the adaptability of C.albicans to oxidative stress.
ABSTRACT
To investigate the synergistic effect of tetrandrine (TET) to the anti-Trichophyton mentagrophytes activity of econazole (ECZ) in vivo,animal model of dermatophytosis in guinea pig was established by inoculating Trichophyton mentagrophytes conidia.These 40 infected animals were divided into 4 groups randomly and from Day 5 after inoculation,they were treated with the following formulations once per day for successive 14 days: 1% econazole and 1% tetrandrine compound cream (1%ECZ+1%TET group),1% econazole cream (1%ECZ group),1%TET cream (1%TET group) and matrix cream (matrix group).The alterations in the skin lesions and the pathological changes were observed.From the 4~(th) day of drugs applying,the tendency of lesion score about 1%ECZ+1%TET group continued to decline.On the 14~(th) day of drugs applying,the lesion score decreased to 0.75.There was a similarity between 1%ECZ+1%TET group and 1%ECZ group in tendency of lesion score,but more reduction was appeared in 1%ECZ+1%TET group than in 1%ECZ group (mean 0.75 VS 2.00) with obviously statistical difference (P=0.037).The culture results of skin sections and the pathological changes in 1%ECZ+1%TET group were less than those of other 3 groups.It's predicted that there is a synergistic effect of tetrandrine to the anti-Trichophyton mentagrophytes of econazole in animal model of dermatophytosis in guinea pig.