Glucosylceramide Plays a Role in Fungal Germination, Lipid Raft Organization and Biofilm Adhesion of the Pathogenic Fungus Scedosporium aurantiacum

Victor Pereira Rochetti,Rodrigo Rollin-Pinheiro,Evely Bertulino De Oliveira,Mariana Ingrid Dutra Da Silva Xisto,Eliana Barreto-Bergter

doi:10.3390/jof6040345

Victor Pereira Rochetti, Rodrigo Rollin-Pinheiro + Show 3 more

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https://doi.org/10.3390/jof6040345

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Abstract

Infections caused by Scedosporium species present a wide range of clinical manifestations, from superficial to disseminated, especially in immunocompromised patients. Glucosylceramides (GlcCer) are glycosphingolipids found on the fungal cell surface and play an important role in growth and pathogenicity processes in different fungi. The present study aimed to evaluate the structure of GlcCer and its role during growth in two S. aurantiacum isolates. Purified GlcCer from both isolates were obtained and its chemical structure identified by mass spectrometry. Using ELISA and immunofluorescence techniques it was observed that germination and NaOH-treatment of conidia favor GlcCer exposure. Monoclonal anti-GlcCer antibody reduced germination when cultivated with the inhibitor of melanin synthesis tricyclazole and also reduced germ tube length of conidia, both cultivated or not with tricyclazole. It was also demonstrated that anti-GlcCer altered lipid rafts organization, as shown by using the fluorescent stain filipin, but did not affect the susceptibility of the cell surface to damaging agents. Anti-GlcCer reduced total biomass and viability in biofilms formed on polystyrene plates. In the presence of anti-GlcCer, germinated S. aurantiacum conidia and biofilms could not adhere to polystyrene with the same efficacy as control cells. These results highlight the relevance of GlcCer in growth processes of S. aurantiacum.

Highlights

Scedosporium and Lomentospora species are ubiquitous filamentous fungi, commonly found in areas impacted by humans
Purified GlcCer obtained from S. aurantiacum WM 09.12 and WM 06.385 was analyzed by electrospray ionization mass spectrometry (ESI-MS)
The major ion species at m/z 750 was submitted to tandem fragmentation (ESI-MS/MS) and three daughter ions were identified at m/z 588 corresponding to the ceramide mono-lithiated from the parental ion, m/z 496 corresponding to a hydroxylated C16-fatty acid, and a fragment at m/z 187 confirmed the presence of a hexose (Figure 1B)

Summary

Introduction

Scedosporium and Lomentospora species are ubiquitous filamentous fungi, commonly found in areas impacted by humans. They cause disease in both immunocompetent and immunocompromised patients, ranging from localized to disseminated infections [1,2,3]. These fungal species are multidrug resistant and highly associated with respiratory tract colonization in cystic fibrosis patients [4,5,6]. Within the Scedosporium genus, Scedosporium aurantiacum is a clinically relevant species that was related to severe disseminated infections and brain abscesses [7,8]. Some aspects correlated to S. aurantiacum virulence include the capacity for germination under host conditions and rapid formation of robust biofilms on various types of surfaces, such as central venous catheter and tissue culture dishes [11,12]

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