Onderzoek naar de rol van enzymen van het trehalosemetabolisme bij stress, resistentie tegen anti-schimmel middelen en virulentie van de menselijke schimmelpathogenen Candida glabrata en Candida auris
Year: 2025
Type: dissertation
Abstract: Invasive fungal infections caused by human fungal pathogens represent a growing public health concern, which always associated with high morbidity and mortality, and their treatment is increasingly challenged by the emergence of high antifungal resistance and tolerance. The rising incidence of fungal infections, especially those caused by Candida species, poses a substantial threat to global health. Notably, Nakaseomyces glabratus (Candida glabrata) and Candidozyma auris (Candida auris) have drawn attention due to their high resistance to antifungal drugs and environmental stresses. However, the molecular mechanisms underlying this intrinsic resistance remain incompletely understood. We investigated whether trehalose, a sugar involved in stress tolerance in many micro-organisms, could be involved in this process. Our research demonstrated that the trehalose biosynthesis pathway plays a critical role in stress adaptation, antifungal drug response, and virulence in C. glabrata and C. auris, although with species-specific differences. To investigate the potential of trehalose biosynthesis enzymes as antifungal drug targets, we characterized three key enzymes—Tps1, Tps2, and Nth1—and assessed their functional roles in stress resistance, antifungal susceptibility, and virulence in these two species. C. glabrata is an opportunistic human fungal pathogen responsible for both superficial mucosal and life-threatening bloodstream infections. Characterized by its remarkable resilience to environmental stressors, C. glabrata exhibits intrinsic tolerance to azoles and a high tendency to develop azole resistance during treatment. In this study, we found that the tps2Δ strain, which accumulates high levels of T6P and reduced levels of trehalose, is more sensitive to specific environmental stress and has a loss of fluconazole tolerance, as indicated by the absence of slow growth at supra-MIC concentrations. These phenotypes were reversed in the nth1Δ strain, which accumulates high levels of trehalose. Our findings highlight the role of trehalose in enabling fluconazole tolerance in C. glabrata and suggest that this effect may be mediated through changes in its sterol composition. As a multidrug-resistant fungal pathogen, C. auris poses a significant public health challenge due to high mortality rates and limited treatment options. Echinocandins, which target β-glucan synthesis, are currently the first-line therapy for invasive C. auris infections. However, resistance to this drug class is increasing, emphasizing the urgent need for novel antifungal targets. This study investigated the role of trehalose biosynthesis in C. auris. We found that the tps2Δ strain exhibited heightened susceptibility to echinocandins, while the tps1Δ and tps1Δtps2Δ strains exhibited the same levels of resistance and tolerance as the WT which revealed a link between T6P accumulation and impaired chitin biosynthesis. In the absence of T6P (as in the tps1Δ or tps1Δtps2Δ strains), hexokinase activity increased and glycolytic flux was enhanced, without significantly affecting chitin levels. In contrast, the tps2Δ strain accumulated T6P, leading to hexokinase inhibition and reduced Glucose 6-phosphate flux into the chitin biosynthesis pathway, thereby decreasing the chitin content of the cell wall. The inability to compensate for reduced β-glucan levels with increased chitin synthesis during echinocandin treatment enhanced the tps2Δ strain highly susceptible to echinocandins. Furthermore, in a systemic infection model, the tps2Δ strain exhibited reduced fungal burden in host tissues, and infected mice showed marked improvement during caspofungin treatment. These findings suggest that Tps2 is a promising target for enhancing echinocandin efficacy in C. auris. As trehalose enzymes are not present in humans, this makes them ideal antifungal drug targets.
Source: Lirias
Author: Zhu, Qingjuan
Language: English
Subfield: Infectious Diseases
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7112511491
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