Novel ABC Transporter Associated with Fluconazole Resistance in Aging of Cryptococcus neoformans

Oliveira, Natalia Kronbauer; Bhattacharya, Somanon; Gambhir, Rina; Joshi, Manav; Fries, Bettina C.

doi:10.20944/preprints202201.0263.v1

Cited by 6 publications

References 43 publications

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Achieving Resilience in Aging: How Mitochondrial Modulation Drives Age-associated Fluconazole Tolerance inCryptococcus neoformans

Yoo,

Oliveira,

Bhattacharya

et al. 2024

Preprint

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Cryptococcus neoformans(Cn) is an opportunistic fungal microorganism that causes life-threatening meningoencephalitis. During the infection, the microbial population is heterogeneously composed of cells with varying generational ages, with older cells accumulating during chronic infections. This is attributed to their enhanced resistance to phagocytic killing and tolerance of antifungals like fluconazole (FLC). In this study, we investigated the role of ergosterol synthesis, ATP-binding cassette (ABC) transporters, and mitochondrial metabolism in the regulation of age-dependent FLC tolerance. We find that oldCncells increase the production of ergosterol and exhibit upregulation of ABC transporters. Old cells also show transcriptional and phenotypic characteristics consistent with increased metabolic activity, leading to increased ATP production. This is accompanied by increased production of reactive oxygen species (ROS), which results in mitochondrial fragmentation. This study demonstrates that the metabolic changes occurring in the mitochondria of old cells drive the increase in ergosterol synthesis and the upregulation of ABC transporters, leading to FLC tolerance.IMPORTANCEInfections caused byCryptococcus neoformanscause more than 180,000 deaths annually. Estimated one-year mortality for patients receiving care ranges from 20% in developed countries to 70% in developing countries, suggesting that current treatments are inadequate. Some fungal cells can persist and replicate despite the usage of current antifungal regimens, leading to death or treatment failure. In replicative aging, older cells display a resilient phenotype, characterized by their enhanced tolerance against antifungals and resistance to killing by host cells. This study shows that age-dependent increase in mitochondrial reactive oxygen species drive changes in ABC transporters and ergosterol synthesis, ultimately leading to the heightened tolerance against fluconazole in oldC. neoformanscells. Understanding the underlying molecular mechanisms of this age-associated antifungal tolerance will enable more targeted antifungal therapies for cryptococcal infections.

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Achieving Resilience in Aging: How Mitochondrial Modulation Drives Age-associated Fluconazole Tolerance inCryptococcus neoformans

Yoo,

Oliveira,

Bhattacharya

et al. 2024

Preprint

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Lack of an atypical PDR transporter generates an immunogenicCryptococcus neoformansstrain that drives a dysregulated and lethal immune response in murine lungs

Winski,

Stuckey,

Marrufo

et al. 2024

Preprint

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Cryptococcus neoformansis an opportunistic fungal pathogen responsible for >150,000 deaths every year with a mortality rate as high as 81%. This high medical burden is due, in part, to an incomplete understanding of its pathogenesis. In a previous study, we identified a cryptococcal atypical pleiotropic drug resistance (PDR) transporter,PDR6, that regulated antifungal resistance and host interactions. Here, we follow-up on the role ofPDR6in cryptococcal virulence.In vivo, mice infected with thepdr6Δ strain display altered symptomatology and disease progression. Specifically, we observed a significant increase in the innate immune cell populations in thepdr6Δ-infected mice when compared to their WT-infected littermates. Furthermore, quantification of pulmonary cytokines/chemokines revealed a robust increase of pro-inflammatory cytokines in mice infected with thepdr6Δ mutant strain. Whereas antifungal treatment ofpdr6Δ-infected animals did not affect survival, treatment with a corticosteroid significantly extended survival, highlighting the importance of a balanced/controlled host immune response. We determined that the hyper-inflammatory immune response occurs, in part, because the loss of the Pdr6 transporter indirectly alters the cryptococcal cell wall architecture and results in the increased exposure of chitin, β-glucan, and other cryptococcal-specific pathogen associated molecular patterns. Taken together, this study provides clinical insights regarding cryptococcal pathogenesis while also providing additional functions of PDR-type ATP-binding cassette (ABC) transporters in pathogenic fungi.IMPORTANCEYeasts of theCryptococcusgenus, especiallyC. neoformans, can cause disease with unacceptably high mortality. This is due to delays in diagnostics, ineffective treatments, and an incomplete understanding of the interactions between this fungus and our immune system. In this study, we expand our knowledge of the biological function of thePDR6gene, particularly its effect on modulating the host’s immune response. Normally,C. neoformans’s infections are characterized by an anti-inflammatory response that is unable to control the yeast. In the absence ofPDR6, the response to the infection is a dysregulated pro-inflammatory response that initially controls the fungi but eventually results in death of the host due to too much tissue damage. This is due, in part, to an altered fungal surface. Given the dual role ofPDR6in modulating antifungal sensitivity and immune responses, this work provides important insights that may lead to new or improved therapeutics.

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Transcriptomics uncovers key genes for photodynamic killing on Trichosporon asahii biofilms

Luo,

Wang,

Chang

et al. 2023

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The escalating threat of antifungal resistance stemming from Trichosporon asahii (T. asahii) biofilms necessitates the pursuit of innovative therapeutic strategies. Among these approaches, 5-aminolevulinic acid (ALA) photodynamic therapy (PDT), an emerging therapeutic modality, has exhibited promising potential in eradicating T. asahii biofilms. To delve deeper into the efficacy of ALA-PDT in eliminating T. asahii biofilms, we conducted a comprehensive transcriptional analysis utilizing transcriptome sequencing (RNA-Seq). Notably, ALA-PDT demonstrated a profound inhibitory effect on the viability of T. asahii biofilms. Therefore, we selected T. asahii biofilms subjected to ALA-PDT treatment for transcriptome analysis and compared them to the control group. Our investigation unveiled 2,720 differentially expressed genes (DEGs) following exposure to ALA-PDT. Subsequent meticulous scrutiny allowed for the annotation of genes with a ≥ 2-fold change in transcription, focusing on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Particularly noteworthy were the upregulated genes associated with oxidation-reduction processes, oxidoreductase activity, and catalytic activity. Conversely, the downregulated genes were linked to ATP binding, protein phosphorylation, and protein kinase activity. Additionally, we observed a surge in the transcription of genes that may be involved in oxidative stress (A1Q1_05494) as well as genes that may be involved in morphogenesis and biofilm formation (A1Q1_04029, A1Q1_01345, A1Q1_08069, and A1Q1_01456) following ALA-PDT treatment. Collectively, our findings underscore the substantial impact of ALA-PDT on the transcriptional regulation of genes related to oxidative stress, morphogenesis, and biofilm formation, paving the way for novel therapeutic avenues in combating T. asahii biofilms.

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Novel ABC Transporter Associated with Fluconazole Resistance in Aging of Cryptococcus neoformans

Cited by 6 publications

References 43 publications

Achieving Resilience in Aging: How Mitochondrial Modulation Drives Age-associated Fluconazole Tolerance inCryptococcus neoformans

Achieving Resilience in Aging: How Mitochondrial Modulation Drives Age-associated Fluconazole Tolerance inCryptococcus neoformans

Lack of an atypical PDR transporter generates an immunogenicCryptococcus neoformansstrain that drives a dysregulated and lethal immune response in murine lungs

Transcriptomics uncovers key genes for photodynamic killing on Trichosporon asahii biofilms

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