In vitro Paracoccidioides brasiliensisbiofilm and gene expression of adhesins and hydrolytic enzymes

Abstract

Paracoccidioides species are dimorphic fungi that initially infect the lungs but can also spread throughout the body. The spreading infection is most likely due to the formation of a biofilm that makes it difficult for the host to eliminate the infection. Biofilm formation is crucial for the development of infections and confines the pathogen to an extracellular matrix. Its presence is associated with antimicrobial resistance and avoidance of host defenses. This current study provides the first description of biofilm formation by Paracoccidioides brasiliensis (Pb18) and an analysis of gene expression, using real-time PCR, associated with 3 adhesins and 2 hydrolytic enzymes that could be associated with the virulence profile. Biofilm formation was analyzed using fluorescence microscopy, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Metabolic activity was determined using the XTT reduction assay. P. brasiliensis was able to form mature biofilm in 144 h with a thickness of 100 μm. The presence of a biofilm was found to be associated with an increase in the expression of adhesins and enzymes. GP43, enolase, GAPDH and aspartyl proteinase genes were over-expressed, whereas phospholipase was down-regulated in biofilm. The characterization of biofilm formed by P. brasiliensis may contribute to a better understanding of the pathogenesis of paracoccidioidomycosis as well as the search for new therapeutic alternatives; while improving the effectiveness of treatment.

Paracoccidioides-host Interaction: An Overview on Recent Advances in the Paracoccidioidomycosis

“…Therefore, their effective adherence contributes to higher speed invasion of host cells, allowing for evasion of the immune system, establishment of the infection, and in the case of Paracoccidioides spp., lead to different clinical manifestations ( Singer-Vermes et al, 1994 ; de Oliveira et al, 2015 ). Another important fact is that P. brasiliensis is able to form biofilm in vitro , which opens up new possibilities in understanding the infection process of these fungi, since biofilm formation is a condition that provides for the pathogen’s protection against drugs and the host’s immune system ( Sardi et al, 2015 ).…”

New insights into a complex fungal pathogen: the case of Paracoccidioides spp.

“…More recently, it has been reported that P . brasiliensis yeasts are able to form biofilms and that their presence is associated with overexpression of adhesins and enzymes (Sardi et al ., ).…”

Anti-Immune Strategies of Pathogenic Fungi

“…Growth in a mass increases the resistance of the organisms to environmental stress, their resistance to antifungal activities and also effectively shields them from attack by phagocytes (Williams and Ramage, 2015). Fungi that are capable of forming biofilms are C. albicans (Zelante et al, 2012), C. neoformans, H. casulatum, P. brasiliensis , and A. fumigatus (Ramage et al, 2009; Pitangui et al, 2015; Sardi et al, 2015). …”