Extracellular Vesicles From Sporothrix brasiliensis Are an Important Virulence Factor That Induce an Increase in Fungal Burden in Experimental Sporotrichosis.

Marcelo Augusto Kazuo Ikeda,Julia Pinheiro Chagas Da Cunha,Sandro Rogério De Almeida,Karen Spadari Ferreira,André Cronemberger-Andrade,Grasielle Pereira Jannuzzi,José Roberto Fogaça De Almeida,Ana Cláudia Trocoli Torrecilhas,Nilmar Silvio Moretti

doi:10.3389/fmicb.2018.02286

Marcelo Augusto Kazuo Ikeda, Julia Pinheiro Chagas Da Cunha + Show 7 more

Open Access

https://doi.org/10.3389/fmicb.2018.02286

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Abstract

Sporotrichosis is a mycosis that affects the skin, lymphatic system and other organs in humans and animals. The disease has a worldwide distribution, with endemic areas in Brazil, and is caused by a complex of species, including Sporothrix brasiliensis. Some fungi release extracellular vesicles (EVs) that can interact with the host cell and modulate the host immune response. The aim of this study was to analyze the participation of S. brasiliensis EVs in the modulation of dendritic cells (DCs) and in the control of infection in vivo. Our results showed that in vitro, the EVs isolated from S. brasiliensis induced an increase in the phagocytic index and fungal burden in DCs. In addition, we observed a significant increase in IL-12p40 and TNF-α cytokine production. Then, the EVs were inoculated into BALB/c mice before subcutaneous infection with yeast, and the lesion was analyzed after 21, 35, and 42 days. An increase in fungal burden and lesion diameter were observed after 21 days in mice inoculated with a high concentration of EVs. However, after 35 days, we observed a regression of the lesion, which persisted until 42 days after infection. Interestingly, we observed an increase in fungal burden in these mice. In addition, we observed the presence of immunogenic components and proteins that could be related with virulence in EVs. These results suggest that EVs can play an important role in virulence and modulation of the host immune system during experimental S. brasiliensis infection.

Highlights

Fungal infections affect billions of people worldwide being a global concern for public health organizations (Gow and Netea, 2016)
To evaluate the release of Extracellular vesicles (EVs), yeasts from S. brasiliensis were cultured in brain heart infusion (BHI) broth for 6 days, and samples collected for Transmission Electron Microscopy (TEM) and Nanoparticle Tracking Analysis (NTA) analysis
NTA analysis of EV isolated from the supernatant of the culture by differential centrifugation, showed samples with EVs of a mean size ranging from 50 to 150 nm and with a mean concentration of 1.19 × 1011 particles/mL (Figure 2)

Summary

Introduction

Fungal infections affect billions of people worldwide being a global concern for public health organizations (Gow and Netea, 2016). Fungal EVs are associated with the transport of molecules across the cell wall along with the delivery of RNA, lipids, polysaccharides, proteins and immunoreactive components (Joffe et al, 2016; Rizzo et al, 2017). These EVs components can interact with host immune cells, contributing to drug resistance, and faciliting cell invasion and pathogenesis (Oliveira et al, 2010; Brown et al, 2015; da Silva et al, 2016). During the infection process, the pathogen can release EVs that can circulate in body fluids and interact with different host cells, as shown in C. neoformans, where EVs were able to cross the blood-brain barrier, enhancing fungi pathogenesis in the brain (Huang et al, 2012)

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