Phospholipase gene expression during Paracoccidioides brasiliensis morphological transition and infection

Gene expression of Paracoccidioides virulence factors after interaction with macrophages and fibroblasts

BACKGROUND

Paracoccidioidomycosis (PCM) is a systemic mycosis with high prevalence in Latin America that is caused by thermodimorphic fungal species of the Paracoccidioides genus.

OBJECTIVES

In this study, we used quantitative polymerase chain reaction (qPCR) to investigate the expression of genes related to the virulence of Paracoccidioides brasiliensis (Pb18) and P. lutzii (Pb01) strains in their mycelial (M) and yeast (Y) forms after contact with alveolar macrophages (AMJ2-C11 cell line) and fibroblasts (MRC-5 cell line).

METHODS

The selected genes were those coding for 43 kDa glycoprotein (gp43), enolase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 14-3-3 protein (30 kDa), phospholipase, and aspartyl protease.

FINDINGS

In the Pb18 M form, the aspartyl protease gene showed the highest expression among all genes tested, both before and after infection of host cells. In the Pb18 Y form after macrophage infection, the 14-3-3 gene showed the highest expression among all genes tested, followed by the phospholipase and gp43 genes, and their expression was 50-fold, 10-fold, and 6-fold higher, respectively, than that in the M form. After fibroblast infection with the Pb18 Y form, the 14-3-3 gene showed the highest expression, followed by the phospholipase and aspartyl protease genes, and their expression was 25-fold, 10-fold, and 10-fold higher, respectively, than that in the M form. Enolase and aspartyl protease genes were expressed upon infection of both cell lines. After macrophage infection with the Pb01 Y form, the 14-3-3 gene showed the highest expression, followed by the phospholipase and aspartyl protease genes, and their expression was 18-fold, 12.5-fold, and 6-fold higher, respectively, than that in the M form.

MAIN CONCLUSIONS

In conclusion, the data show that the expression of the genes analysed may be upregulated upon fungus-host interaction. Therefore, these genes may be involved in the pathogenesis of paracoccidioidomycosis.

Beyond Melanin: Proteomics Reveals Virulence-Related Proteins in Paracoccidioides brasiliensis and Paracoccidioides lutzii Yeast Cells Grown in the Presence of L-Dihydroxyphenylalanine

Species of the genus Paracoccidioides cause a systemic infection in human patients. Yeast cells of Paracoccidioides spp. produce melanin in the presence of L-dihydroxyphenylalanine and during infection, which may impact the pathogen’s survival in the host. To better understand the metabolic changes that occur in melanized Paracoccidioides spp. cells, a proteomic approach was performed to compare melanized and non-melanized Paracoccidioides brasiliensis and Paracoccidioides lutzii yeast cells. Melanization was induced using L-dihydroxyphenylalanine as a precursor, and quantitative proteomics were performed using reversed-phase nano-chromatography coupled to high-resolution mass spectrometry. When comparing melanized versus non-melanized cells, 1006 and 582 differentially abundant/detected proteins were identified for P. brasiliensis and P. lutzii, respectively. Functional enrichment and comparative analysis revealed 30 important KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways in melanized P. brasiliensis and 18 in P. lutzii, while differentially abundant proteins from non-melanized cells from these species were involved in 21 and 25 enriched pathways, respectively. Melanized cells presented an abundance of additional virulence-associated proteins, such as phospholipase, proteases, superoxide dis-mutases, heat-shock proteins, adhesins, and proteins related to vesicular transport. The results suggest that L-dihydroxyphenylalanine increases the virulence of Paracoccidioides spp. through complex mechanisms involving not only melanin but other virulence factors as well.

Virulence factors of Paracoccidioides brasiliensis as therapeutic targets: a review

Paracoccidiodomycosis (PCM) is a systemic mycosis caused by the fungus Paracoccidioides brasiliensis and Paracoccidioides lutzii. The disease requires long and complicated treatment. The aim of this review is to address the fungal virulence factors that could be the target of the development of new drugs for PCM treatment. Virulence factors favoring the process of fungal infection and pathogenicity are considered as a microbial attribute associated with host susceptibility. P. brasiliensis has some known virulence factors which are 43 kDa glycoprotein (gp 43) which is an important fungal antigen, 70 kDa glycoprotein (gp 70), the carbohydrates constituting the fungal cell wall α-1,3, glucan and β-1,3-glucan, cell adhesion molecules and the presence of melanin pigments. The discovery and development of drugs that interact with these factors, such as inhibitors of β-1,3-glucan, reduced synthesis of gp 43, inhibitors of melanin production, is of great importance for the treatment of PCM. The study of virulence factors favors the understanding of pathogen-host relationships, aiming to evaluate the possibility of developing new therapeutic targets and mechanisms that these molecules play in the infectious process, favoring the design of a more specific treatment for this disease.

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

Paracoccidioidomycosis is a systemic mycosis endemic to Latin America, with Paracoccidioides brasiliensis and P. lutzii being the causal agents of this disorder. Several issues have been raised in the 100 years since its discovery and in this article we discuss features of this fascinating fungal pathogen, including its biology, eco-epidemiology and aspects of its pathogenicity. We also consider some of its virulence determinants, the most recent advances in the study of its metabolic pathways and the molecular and genetic research tools developed for this research. We also review the animal models used to study host-fungal interactions and how the host defence mechanisms against this pathogen work.

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

Paracoccidioides brasiliensis and P. lutzii are etiologic agents of paracoccidioidomycosis (PCM), an important endemic mycosis in Latin America. During its evolution, these fungi have developed characteristics and mechanisms that allow their growth in adverse conditions within their host through which they efficiently cause disease. This process is multi-factorial and involves host-pathogen interactions (adaptation, adhesion, and invasion), as well as fungal virulence and host immune response. In this review, we demonstrated the glycoproteins and polysaccharides network, which composes the cell wall of Paracoccidioides spp. These are important for the change of conidia or mycelial (26°C) to parasitic yeast (37°C). The morphological switch, a mechanism for the pathogen to adapt and thrive inside the host, is obligatory for the establishment of the infection and seems to be related to pathogenicity. For these fungi, one of the most important steps during the interaction with the host is the adhesion. Cell surface proteins called adhesins, responsible for the first contact with host cells, contribute to host colonization and invasion by mediating this process. These fungi also present the capacity to form biofilm and through which they may evade the host's immune system. During infection, Paracoccidioides spp. can interact with different host cell types and has the ability to modulate the host's adaptive and/or innate immune response. In addition, it participates and interferes in the coagulation system and phenomena like cytoskeletal rearrangement and apoptosis. In recent years, Paracoccidioides spp. have had their endemic areas expanding in correlation with the expansion of agriculture. In response, several studies were developed to understand the infection using in vitro and in vivo systems, including alternative non-mammal models. Moreover, new advances were made in treating these infections using both well-established and new antifungal agents. These included natural and/or derivate synthetic substances as well as vaccines, peptides, and anti-adhesins sera. Because of all the advances in the PCM study, this review has the objective to summarize all of the recent discoveries on Paracoccidioides-host interaction, with particular emphasis on fungi surface proteins (molecules that play a fundamental role in the adhesion and/or dissemination of the fungi to host-cells), as well as advances in the treatment of PCM with new and well-established antifungal agents and approaches.