Caspofungin Affects Extracellular Vesicle Production and Cargo in Candida auris.

Antifungal resistance has become more frequent, either due to the emergence of naturally resistant species or the development of mechanisms that lead to resistance in previously susceptible species. Among these fungal species of global threat, Candida auris stands out for commonly being highly resistant to antifungal drugs, and some isolates are pan-resistant. The rate of mortality linked to C. auris infections varies from 28% to 78%. In this study, we characterized C. auris extracellular vesicles (EVs) in the presence of caspofungin, an echinocandin, which is the recommended first line antifungal for the treatment of infections due to this emerging pathogen. Furthermore, we also analyzed the protein and RNA content of EVs generated by C. auris cultivated with or without treatment with caspofungin. We observed that caspofungin led to the increased production of EVs, and treatment also altered the type and quantity of RNA molecules and proteins enclosed in the EVs. There were distinct classes of RNAs in the EVs with ncRNAs being the most identified molecules, and tRNA-fragments (tRFs) were abundant in each of the strains studied. We also identified anti-sense RNAs, varying from 21 to 55 nt in length. The differentially abundant mRNAs detected in EVs isolated from yeast subjected to caspofungin treatment were related to translation, nucleosome core and cell wall. The differentially regulated proteins identified in the EVs produced during caspofungin treatment were consistent with the results observed with the RNAs, with the enriched terms being related to translation and cell wall. Our study adds new information on how an echinocandin can affect the EV pathway, which is associated with the yeast cell being able to evade treatment and persist in the host. The ability of C. auris to efficiently alter the composition of EVs may represent a mechanism for the fungus to mitigate the effects of antifungal agents.

Cellular and Extracellular Vesicle RNA Analysis in the Global Threat Fungus Candida auris.

Emerging and reemerging pathogens are a worldwide concern, and it is predicted that these microbes will cause severe outbreaks. Candida auris affects people with weakened immune systems, particularly those who are hospitalized or are in health care facilities. Extracellular vesicles (EVs) are lipid bilayer structures released by organisms from all domains of life. EVs can deliver functional molecules to target cells, including proteins and nucleic acids, especially RNA molecules. EVs from several pathogenic fungi species play diverse biological roles related to cell-cell communication and pathogen-host interaction. In this study, we describe a data set which we produced by sequencing the RNA content of EVs from C. auris under normal growth conditions and in the presence of the antifungal caspofungin, a first-line drug to treat this fungus. To generate a more complete data set for future comparative studies, we also sequenced the RNA cellular content of EVs under the same conditions. This data set addresses a previously unexplored area of fungal biology regarding cellular small RNA and EV RNA. Our data will provide a molecular basis for the study of the aspects associated with antifungal treatment, gene expression response, and EV composition in C. auris. These data will also allow the exploration of small RNA content in the fungal kingdom and might serve as an informative basis for studies on the mechanisms by which molecules are directed to fungal EVs. IMPORTANCE Candida auris, a relevant emerging human-pathogenic yeast, is the first fungus to be called a global public health threat by the WHO. This is because of its rapid spread on all inhabited continents, together with its extremely high frequency of drug and multidrug resistance. In our study, we generated a large data set for 3 distinct strains of C. auris and obtained cellular small RNA fraction as well as extracellular vesicle RNA (EV-RNA) during normal growth conditions and after treatment with caspofungin, the first-line drug used to treat C. auris infection.

Transcriptional and translational landscape of Candida auris in response to caspofungin.

Candida auris has emerged as a serious worldwide threat by causing opportunistic infections that are frequently resistant to one or more conventional antifungal medications resulting in high mortality rates. Against this backdrop, health warnings around the world have focused efforts on understanding C. auris fungal biology and effective prevention and treatment approaches to combat this fungus. To date, there is little information about the differentially expressed genes when this fungus is treated with conventional antifungals, and caspofungin is a standard echinocandin deployed in the therapy against C. auris. In this work, we treated two distinct strains of C. auris for 24 h with caspofungin, and the cellular responses were evaluated at the morphological, translational and transcriptional levels. We first observed that the echinocandin caused morphological alterations, aggregation of yeast cells, and modifications in the cell wall composition of C. auris. Transcriptomic analysis revealed an upregulation of genes related to the synthesis of the cell wall, ribosome, and cell cycle after exposure to caspofungin. Supporting these findings, the integrated proteomic analysis showed that caspofungin-treated cells were enriched in ribosome-related proteins and cell wall, especially mannoproteins. Altogether, these results provide further insights into the biology of C. auris and expands our understanding regarding the antifungal activity of caspofungin and reveal cellular targets, as the mannose metabolism, that can be further explored for the development of novel antifungals.