The Mechanism Of Polyamines In Resistance In Candida Albicans

Candida albicans (C. albicans) is a common opportunistic human fungal pathogenand could cause invasive infections varying from superficial mucosal infections tolife-threatening systemic diseases. C. albicans is known to be resistant to differentantifungal agents and this resistance represents a serious threat to publish health. Therefore,it is critical to clear the mechanisms of resistance in C. albicans to provide the newstrategy for drug treatment. C. albicans metabonomics studies have found that polyaminecontent is increased in AmB treatment group. Polyamines are small aliphatic hydrocarbonmolecules containing two or more amine groups, including putrescine, spermidine andspermine. And polyamines play an important role in plant resistance and bacterial drugresistance, and it could stimulate the hyphae formation which is an important virulencefactor in C. albicans. Therefore, we hypothesized that polyamine may participate in theprocess of drug resistance in C. albicans.In this work, we first respectively investigated the effect of polyamines on C. albicansexposed to fluconazole, miconazole, caspofungin, nystatin, amphotericin B (AmB) andshikonin. It is found polyamines at3mM could apparently attenuate the antifungal activityof caspofungin, nystatin, AmB and shikonin. C. albicans growth curve and survivalexperiments confirmed previous results. We investigated the effect of polyamines onbiofilms exposed to AmB and found polyamines at3mM could apparently attenuate theantibiofilm activity of AmB by XTT reduction assay and scanning electron microscopy(SEM). Meanwhile, SPE1Δ/Δ mutant strain show higher sensitivity to AmB than widetype strain. And exogenous adding polyamine could reduce sensitivity to AmB. Thissuggests that polyamine could reduce sensitivity to AmB in C. albicans, inducingresistance in C. albicans.In this work, we clarify the mechanisms of polyamine participate in drug resistance inC. albicans from two aspects of oxidative stress and biofilm formation. DCFH-DA dyeingmethod was used to detect the contents of intracellular reactive oxygen species (ROS) in C.albicans and Real Time RT-PCR method was used to detect the expression levels of someimportant oxidative stress-related genens, the results showed that AmB/polyamines couldsignificantly reduce the level of endogenous ROS and downregulate the expression levelsof SOD2, SOD5, EBP1and MRF1. Theses results indicated polyamines could attenuateoxidative injuries of AmB. Cell surface hydrophobicity (CSH) and yeast to hyphae transition states plays a critical role in the biofilm formation. The water-hydrocarbontwo-phase assay showed an increase in cell surface hydrophobicity in the combination ofpolyamines and AmB treated groups compared with AmB used alone. Meanwhile,3mMpolyamines restored partial ability of the hyphal formation in C. albicans exposed to AmBin spider and RPMI1640containing10%FBS culture media. Real-time RT-PCR revealedthat the compounds of polyamines and AmB up-regulated the expression ofbiofilm-regulated genes IFF4, ALS3, ECE1, HWP1, CSH1and RAS1compared with AmBalone. This suggested that sperminde, spermidine and putrescine attenuated theanti-biofilm activity of AmB by enhancing the CSH, hyphae formation and upregulatingthe expression levels of biofilm-related genes.In summary, Polyamines could participate in the process of drug resistance in C.albicans through reducing the intracellular ROS content and enhancing the ability ofbiofilm formation.