RAFT-Derived Polymethacrylates as a Superior Treatment for Recurrent Vulvovaginal Candidiasis by Targeting Biotic Biofilms and Persister Cells

Abstract

BackgroundVulvovaginal candidiasis (VVC) is a common infection in need of more effective treatment. Formation of epithelium-associated Candida biofilms and the presence of persister cells are among the major contributing factors to the recurrence of this condition. We have previously developed RAFT-derived polymethacrylates that are effective in killing C. albicans biofilms in vitro. This study aimed to examine the clinical potential of polymethacrylates as antifungals for treatment of recurrent VVC (RVVC).MethodsA mouse model of VVC was used to establish vaginal epithelium-associated biofilms, using C. albicans isolates from VVC/RVVC patients. A comparison was made of the efficacies of polymethacrylates and conventional antifungals, clotrimazole and nystatin, in killing Candida in epithelium-associated biofilms in vivo. Ex vivo biofilms were used for Candida population profiling and to quantify persister cells in vaginal epithelia. The potency of polymethacrylates and conventional antifungals against persister cells, either as sole agents or in combination, was assessed.ResultsPolymethacrylates showed negligible local toxicity, resistance to vaginal acidity, and outstanding in vivo activity against vaginal epithelium-associated C. albicans biofilms. In vivo tests polymethacrylates outperformed the conventional antifungals, nystatin and clotrimazole at concentrations 50 times below the over-the-counter concentrations. Using polymethacrylates was associated with fewer persister cells, and better eradication of persister cells pre-selected by conventional antifungals.ConclusionThis study systematically assessed the clinical potential of RAFT-derived polymethacrylates as an effective treatment for VVC/RVVC in a mouse model. Polymethacrylates effectively killed vaginal epithelium-related C. albicans in vivo by specially targeting biotic biofilms and persister cells. Treatment presented negligible local toxicity.

Biofilm Formation of Candida albicans Facilitates Fungal Infiltration and Persister Cell Formation in Vaginal Candidiasis

“…More importantly, epithelium-associated biofilms act as a conducive environment that facilitates the formation of persister cells. Using a regimen that kills the bulk of fungal cells with normal susceptibilities, our recent study has successfully isolated persister cells from the vaginal epithelium of mice infected with C. albicans (Wu et al, 2019). These persister cells could not be eradicated by conventional antifungal drugs at very high concentrations and might be the main culprit responsible for the recalcitrance of infections to antifungal treatment (Wu et al, 2019).…”

“…Using a regimen that kills the bulk of fungal cells with normal susceptibilities, our recent study has successfully isolated persister cells from the vaginal epithelium of mice infected with C. albicans (Wu et al, 2019). These persister cells could not be eradicated by conventional antifungal drugs at very high concentrations and might be the main culprit responsible for the recalcitrance of infections to antifungal treatment (Wu et al, 2019). The current study further established a connection between biofilm growth by C. albicans in the vaginal epithelium and the formation of persister cells, supporting a role of Candida biofilm formation in the recurrence of vaginal candidiasis.…”

“…Colony-forming units counting was done by plating serially diluted aliquots onto YPD plates followed by incubation at 35 • C for 72 h to maximize recovery of persister cells. The percentage of persister cells in different populations was calculated as follows: (fungal density after antifungal treatment)/(fungal density before antifungal treatment) × 100%, as described before (Wu et al, 2019).…”

“…Treatment of persister cells is known to be troublesome. Conventional antimicrobial agents, unless used at very high dose for an extended period, will not eradicate persister cells residing in biofilms (Yang et al, 2015;Wu et al, 2019). Our study aimed to establish a comprehensive understanding of the importance of C. albicans biofilm formation in the pathogenesis of vaginal candidiasis, in order to identify specific microbial targets for more efficient antifungal therapies.…”

Approaches for the inhibition and elimination of microbial biofilms using macromolecular agents

“…78 Building from this in vitro study, the optimized guanidine copolymers were investigated as a topical treatment against epithelial-associated C. albicans biofilms in an in vivo murine vulvovaginal candidiasis (VVC) model. 143 The results from this study showed that the polymers displayed negligible local toxicity and resistance to vaginal acidity, and that this formulation outperformed conventional antifungal agents at concentrations 50-fold lower than the over-the-counter concentration of the conventional antifungal drugs. Furthermore, topical treatment using these polymers resulted in fewer persister cell survivors in the fungal biofilms in comparison with conventional antifungals.…”