Involvement of Dihydrolipoyl Dehydrogenase in the Phagocytosis and Killing of Paracoccidioides brasiliensis by Macrophages.

Taise N Landgraf,Wander C Ribeiro,Ademilson Panunto-Castelo,Aline F Oliveira,Fabrício F Fernandes,Marcelo V Costa

doi:10.3389/fmicb.2017.01803

Taise N Landgraf, Wander C Ribeiro + Show 4 more

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https://doi.org/10.3389/fmicb.2017.01803

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Abstract

Paracoccidioides brasiliensis and Paracoccidioides lutzii are fungi causing paracoccidioidomycosis (PCM), an autochthonous systemic mycosis found in Latin America. These microorganisms contain a multitude of molecules that may be associated with the complex interaction of the fungus with the host. Here, we identify the enzyme dihydrolipoyl dehydrogenase (DLD) as an exoantigen from P. brasiliensis (Pb18_Dld) by mass spectrometry. Interestingly, the DLD gene expression in yeast form showed higher expression levels than those in mycelial form and transitional phases. Pb18_Dld gene was cloned, and the recombinant protein (rPb18_Dld) was expressed and purified for subsequent studies and production of antibodies. Immunogold labeling and transmission electron microscopy revealed that the Pb18_Dld is also localized in mitochondria and cytoplasm of P. brasiliensis. Moreover, when macrophages were stimulated with rPb18Dld, there was an increase in the phagocytic and microbicidal activity of these cells, as compared with non-stimulated cells. These findings suggest that Pb18_Dld can be involved in the pathogen-host interaction, opening possibilities for studies of this protein in PCM.

Highlights

Paracoccidioidomycosis (PCM) is a chronic granulomatous mycosis caused by thermally dimorphic fungi Paracoccidioides lutzii and P. brasiliensis, which contain a complex of at least four different cryptic species, S1, PS2, PS3, and PS4 (Matute et al, 2006; Carrero et al, 2008; Teixeira et al, 2009, 2014; Theodoro et al, 2012)
To identify new antigens from P. brasiliensis that could be associated with the host, we focused on ExoAgs preparations and isolated a highly expressed protein, identified by mass spectrometry as Pb18_Dld
The fact that Pb18_Dld could be detected in the extracellular extract suggested that it was an ExoAg released by the fungus

Summary

Introduction

Paracoccidioidomycosis (PCM) is a chronic granulomatous mycosis caused by thermally dimorphic fungi Paracoccidioides lutzii and P. brasiliensis, which contain a complex of at least four different cryptic species, S1, PS2, PS3, and PS4 (Matute et al, 2006; Carrero et al, 2008; Teixeira et al, 2009, 2014; Theodoro et al, 2012). The mean annual mortality rate is 1.65 per million inhabitants, the highest for any systemic mycosis, making PCM the eighth most important cause of mortality among chronic or recurrent infectious, parasitic diseases, and infectious diseases in Brazil (Coutinho et al, 2002; Colombo et al, 2011; Bocca et al, 2013). Secretion of antimicrobial proteins by the pulmonary epithelium and phagocytic activity of resident alveolar macrophages mediates the initial response to infection (Calich et al, 2008). Infections can stimulate different subsets of T cells and induce the production of distinct patterns of cytokines that are responsible for the protection or susceptibility of the host to pathogens (Della Bella et al, 2017), including fungal infections (Calich and Kashino, 1998; Oliveira et al, 2002; Romani, 2004)

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