Paracoccidioidomycosis is a systemic fungal infection affecting mainly Latin American countries that is caused by Paracoccidioides brasiliensis and Paracoccidioides lutzii. During the study of fungal ...pathogenesis, in vivo studies are crucial to understand the overall mechanisms involving the infection as well as to search for new therapeutic treatments and diagnosis. Caenorhabditis elegans is described as an infection model for different fungi species and a well-characterized organism to study the innate immune response. This study evaluates C. elegans as an infection model for Paracoccidioides spp. It was observed that both species do not cause infection in C. elegans, as occurs with Candida albicans, and one possible explanation is that the irregular size and shape of Paracoccidioides spp. difficult the ingestion of these fungi by the nematode. Besides this difficulty in the infection, we could observe that the simple exposition of C. elegans to Paracoccidioides species was able to trigger a distinct pattern of expression of antimicrobial peptide genes. The expression of cnc-4, nlpl-27 and nlp-31 was superior after the exposure to P. brasiliensis in comparison to P. lutzii (P < 0.05), and these findings demonstrate important differences regarding innate immune response activation caused by the two species of the Paracoccidioides genus.
The genus Paracoccidioides consist of dimorphic fungi geographically limited to the subtropical regions of Latin America, which are responsible for causing deep systemic mycosis in humans. However, ...the molecular mechanisms by which Paracoccidioides spp. causes the disease remain poorly understood. Paracoccidioides spp. harbor genes that encode proteins involved in host cell interaction and mitochondrial function, which together are required for pathogenicity and mediate virulence. Previously, we identified TufM (previously known as EF-Tu) in Paracoccidioides brasiliensis (PbTufM) and suggested that it may be involved in the pathogenicity of this fungus. In this study, we examined the effects of downregulating PbTUFM using a silenced strain with a 55% reduction in PbTUFM expression obtained by antisense-RNA (aRNA) technology. Silencing PbTUFM yielded phenotypic differences, such as altered translation elongation, respiratory defects, increased sensitivity of yeast cells to reactive oxygen stress, survival after macrophage phagocytosis, and reduced interaction with pneumocytes. These results were associated with reduced virulence in Galleria mellonella and murine infection models, emphasizing the importance of PbTufM in the full virulence of P. brasiliensis and its potential as a target for antifungal agents against paracoccidioidomycosis.
Considering the toxicity of conventional therapeutic approaches and the importance of precise mechanistic targets, it is important to explore signaling pathways implicated in fungal pathobiology. ...Moreover, treatment of paracoccidioidomycosis, a systemic mycosis caused by a dimorphic fungus, requires prolonged therapeutic regimens. Among the numerous factors underpinning the establishment of Paracoccidioides spp. infection, the capacity to transition from the mycelial to the yeast form is of pivotal importance. The Drk1 protein of Paracoccidioides brasiliensis likely plays a decisive role in this morphological shift and subsequent virulence. We identified peptides with affinity for the PbDrk1 protein using the phage-display method and assessed the effects of these peptides on P. brasiliensis. The peptides were found to inhibit the phase transition of P. brasiliensis. Furthermore, a substantial proportion of these peptides prevented adhesion to pneumocytes. Although these peptides may not possess inherent antifungal properties, they can augment the effects of certain antifungal agents. Notably, the cell wall architecture of P. brasiliensis appears to be modulated by peptide intervention, resulting in a reduced abundance of glycosylated proteins and lipids. These peptides were also evaluated for their efficacy in a Galleria mellonella model and shown to contribute to enhanced larval survival rates. The role of PbDrk1, which is notably absent in mammals, should be further investigated to improve the understanding of its functional role in P. brasiliensis, which may be helpful for designing novel therapeutic modalities.
Paracoccidioidomycosis (PCM) is a chronic disease that causes sequelae and requires prolonged treatment; therefore, new therapeutic approaches are necessary. In view of this, three peptides from
...14-3-3 protein were selected based on its immunogenicity and therapeutic potential.
The in vitro antifungal activity and cytotoxicity of the 14-3-3 peptides were evaluated. The influence of the peptides in immunological and survival aspects was evaluated in vivo, using
and the expression of antimicrobial peptide genes in
.
None of the peptides were toxic to HaCaT (skin keratinocyte), MRC-5 (lung fibroblast), and A549 (pneumocyte) cell lines, and only P1 exhibited antifungal activity against
spp. The peptides could induce an immune response in
. Moreover, the peptides caused a delay in the death of
spp. infected larvae. Regarding
, the three peptides were able to increase the expression of the antimicrobial peptides. These peptides had essential effects on different aspects of
spp. infection showing potential for a therapeutic vaccine. Future studies using mammalian methods are necessary to validate our findings.
Paracoccidioides spp., which are temperature-dependent dimorphic fungi, are responsible for the most prevalent human systemic mycosis in Latin America, the paracoccidioidomycosis. The aim of this ...study was to characterise the involvement of elongation factor Tu (EF-Tu) in Paracoccidioides brasiliensis–host interaction. Adhesive properties were examined using recombinant PbEF-Tu proteins and the respective polyclonal anti-rPbEF-Tu antibody. Immunogold analysis demonstrated the surface location of EF-Tu in P. brasiliensis. Moreover, PbEF-Tu was found to bind to fibronectin and plasminogen by enzyme-linked immunosorbent assay, and it was determined that the binding to plasminogen is at least partly dependent on lysine residues and ionic interactions. To verify the participation of EF-Tu in the interaction of P. brasiliensis with pneumocytes, we blocked the respective protein with an anti-rPbEF-Tu antibody and evaluated the consequences on the interaction index by flow cytometry. During the interaction, we observed a decrease of 2- and 3-fold at 8 and 24 h, respectively, suggesting the contribution of EF-Tu in fungal adhesion/invasion.
This article will discuss the identification of novel protein of Paracoccidioides brasiliensis, EF-Tu, which is important to the fungus-host interaction.
14-3-3 proteins comprise a family of eukaryotic multifunctional proteins involved in several cellular processes. The Pb14-3-3 of Paracoccidioides brasiliensis seems to play an important role in the ...Paracoccidioides-host interaction. Paracoccidioides brasiliensis is an etiological agent of paracoccidioidomycosis, which is a systemic mycosis that is endemic in Latin America. In the initial steps of the infection, Paracoccidioides spp. synthetizes adhesins that allow it to adhere and invade host cells. Therefore, the aim of this work was to perform a functional analysis of Pb14-3-3 using Saccharomyces cerevisiae as a model.
The functional analysis of Pb14-3-3 was performed in S. cerevisiae, and it was found that Pb14-3-3 partially complemented S. cerevisiae proteins Bmh1p and Bmh2p, which are recognized as two yeast 14-3-3 homologues. When we evaluated the adhesion profile of S. cerevisiae transformants, Pb14-3-3 acted as an adhesin in S. cerevisiae; however, Bmh1p did not show this function. The influence of Pb14-3-3 in S. cerevisiae ergosterol pathway was also evaluated and our results showed that Pb14-3-3 up-regulates genes involved in ergosterol biosynthesis.
Our data showed that Pb14-3-3 was able to partially complement Bmh1p and Bmh2p proteins in S. cerevisiae; however, we suggest that Pb14-3-3 has a differential role as an adhesin. In addition, Pb-14-3-3 may be involved in Paracoccidioides spp. ergosterol biosynthesis which makes it an interest as a therapeutic target.
As the studies predicting mortality in severe acute respiratory illness (SARI) have inferred associations either from dichotomous outcomes or from time-event models, we identified some ...clinical-epidemiological characteristics and predictors of mortality by comparing and discussing two multivariate models.
To identify factors associated with death among all SARI hospitalizations occurred in Botucatu (Brazil)/regardless of the infectious agent, and among the COVID-19 subgroup, from March 2020 to 2022, we used a multivariate Poisson regression model with binomial outcomes and Cox proportional hazards (time-event). The performance metrics of both models were also analyzed.
A total of 3,995 hospitalized subjects were included, of whom 1338 (33%) tested positive for SARS-CoV-2. We identified 866 deaths, of which 371 (43%) were due to the COVID-19. In the total number of SARI cases, using both Poisson and Cox models, the predictors of mortality were the presence of neurological diseases, immunosuppression, obesity, older age, and need for invasive ventilation support. However, the Poisson test also revealed that admission to an intensive care unit and the COVID-19 diagnosis were predictors of mortality, with the female gender having a protective effect against death. Likewise, Poisson proved to be more sensitive and specific, and indeed the most suitable model for analyzing risk factors for death in patients with SARI/COVID-19.
Given these results and the acute course of SARI and COVID-19, to compare the associations and their different meanings is essential and, therefore, models with dichotomous outcomes are more appropriate than time-to-event/survival approaches.
The excessive plastics production and its inappropriate disposal contribute to unprecedented pollution.
Galleria mellonella
larvae were chosen as the object of this work, in order to evaluate its ...ability to biodegrade two types of plastics most common in everyday life: polystyrene (PS) and low-density polyethylene (LDPE). This research is one of the few that use PS and LDPE as the sole carbon sources in the diet of
G. mellonella
. We studied how contact with larvae affected both types of plastic, covering morphological, physicochemical and mass loss levels. In this particular work, twenty-five larvae were placed inside glass containers in direct contact with the plastics and incubated in the dark at 28 °C. The results showed that PS had greater biodegradation, indicating 56.12% mass loss, while LDPE was 5.11% degraded. After 7.25 days of testing, the larvae survival rate was 60% for PS and 82% for LDPE. The contact with the larvae changed the material wettability, being more noticeable on the PS surface. The formation of new chemical groups indicated the existence of biodegradation processes in the PS sample, but in LDPE no new bands were observed. After 7.25 days, we evaluated larval survival and pupal formation after contact with PS and LPDE, but no significant differences were observed between the groups. No significant difference on the survival and pupa formation of larvae exposed to both types of plastic was found. We conclude that
G. mellonella
larvae can be a cost-effective and promising alternative to biodegrade PS and LDPE pieces in plastic waste environments.
The fungal strain Paracoccidioides brasiliensis remains viable inside of epithelial cells and can induce apoptosis in this population. However, until now, the molecules that participate in this ...process remained unknown. Thus, this study evaluated the contribution of two P. brasiliensis molecules, the 14-3-3 and glycoprotein of 43 kDa proteins, which had been previously described as extracellular matrix adhesins and apoptosis inductors in human pneumocytes. Accordingly, epithelial cells were treated with these molecules for different periods of time and the expression of the apoptosis regulating-proteins Bak, Bax, Bcl-2, p53 and caspases were evaluated by terminal deoxynucleotidyl transferase dUTP nick end labelling, flow cytometry and real-time polymerase chain reaction analysis. Our results demonstrated that treatment with these molecules induces apoptosis signalling in pulmonary epithelial cells, showing the same pattern of programmed cell-death as that observed during infection with P. brasiliensis. Thus, we could conclude that P. brasiliensis uses these molecules as virulence factors that participate not only in the fungal adhesion process to host cells, but also in other important cellular mechanisms such as apoptosis.
Members of the Paracoccidioides genus are the etiologic agents of paracoccidioidomycosis (PCM). This genus is composed of two species: Paracoccidioides brasiliensis and Paracoccidioides lutzii. The ...correct molecular taxonomic classification of these fungi has created new opportunities for studying and understanding their relationships with their hosts. Paracoccidioides spp. have features that permit their growth under adverse conditions, enable them to adhere to and invade host tissues and may contribute to disease development. Cell wall proteins called adhesins facilitate adhesion and are capable of mediating fungi-host interactions during infection. This study aimed to evaluate the adhesion profile of two species of the genus Paracoccidioides, to analyze the expression of adhesin-encoding genes by real-time PCR and to relate these results to the virulence of the species, as assessed using a survival curve in mice and in Galleria mellonella after blocking the adhesins. A high level of heterogeneity was observed in adhesion and adhesin expression, showing that the 14-3-3 and enolase molecules are the most highly expressed adhesins during pathogen-host interaction. Additionally, a survival curve revealed a correlation between the adhesion rate and survival, with P. brasiliensis showing higher adhesion and adhesin expression levels and greater virulence when compared with P. lutzii. After blocking 14-3-3 and enolase adhesins, we observed modifications in the virulence of these two species, revealing the importance of these molecules during the pathogenesis of members of the Paracoccidioides genus. These results revealed new insights into the host-pathogen interaction of this genus and may enhance our understanding of different isolates that could be useful for the treatment of this mycosis.
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