Endemic systemic mycoses remain a health challenge, since these opportunistic diseases are increasingly infecting immunosuppressed patients. The simultaneous use of antifungal compounds and other ...drugs to treat infectious or non-infectious diseases has led to several interactions and undesirable effects. Thus, new antifungal compounds should be investigated. The present study aimed to evaluate the activity of liriodenine extracted from
on agents of systemic mycoses, with emphasis on the genus
.
The minimum inhibitory concentration (MIC) and minimum fungicide concentration (MFC) were determined by the microdilution method. The cellular alterations caused by liriodenine on a standard
(Pb18) strain were evaluated by transmission and scanning electron microscopy.
Liriodenine was effective only in 3 of the 8 strains of the genus
and in the
strain, in a very low concentration (MIC of 1.95 μg.mL
); on yeasts of
spp. (MIC of 125 to 250 μg.mL-1), including
(250 μg.mL
), which has intrinsic resistance to fluconazole; and in
and
(MIC of 62.5 μg.mL
). However, liriodenine was not effective against
at the studied concentrations. Liriodenine exhibited fungicidal activity against all standard strains and clinical isolates that showed to be susceptible by
tests. Electron microscopy revealed cytoplasmic alterations and damage to the cell wall of
(Pb18).
Our results indicate that liriodenine is a promising fungicidal compound that should undergo further investigation with some chemical modifications.
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.
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.
BACKGROUND Paracoccidioides spp. causes paracoccidioidomycosis (PCM), an important and frequent systemic mycosis that occurs in Latin America. The infectious process begins with contact between the ...fungus and lung cells, and the molecular pattern of this interaction is currently poorly understood. MicroRNAs (miRNAs) are small non-coding RNAs that regulate the gene expression in many biological processes, including in the infections. OBJECTIVE This study aimed to analyse the expression of miRNAs in lung cells as response to infection by Paracoccidioides spp. METHODS A quantitative real-time polymerase chain reaction (RT-qPCR) based screening was employed to verify differentially expressed miRNAs in human lung cells infected with three different species; Paracoccidioides lutzii, Paracoccidioides americana, and Paracoccidioides brasiliensis. Furthermore, the in silico predictions of target genes and pathways for miRNAs were obtained. FINDINGS The results showed that miRNAs identified in the lung cells were different according to the species studied. However, based on the predicted targets, the potential signaling pathways regulated by miRNAs are common and related to adhesion, actin cytoskeleton rearrangement, apoptosis, and immune response mediated by T cells and TGF-β. MAIN CONCLUSIONS In summary, this study showed the miRNAs pattern of epithelial cells in response to infection by Paracoccidioides species and the potential role of these molecules in the regulation of key pathogenesis mechanisms of PCM.
Abstract
Paracoccidioidomycosis is a systemic mycosis caused by the dimorphic fungus Paracoccidioides brasiliensis. Understanding the interactions between P. brasiliensis and the host tissue depends ...on the study of the different steps of the process of colonization, especially adhesion, in which the pathogen recognizes ligands on the surface of host cells. This study aimed to verify the role of enolase in the host cell–fungus interaction and the ability of enolase to bind to extracellular matrix components, to determine its subcellular localization, and to study the P. brasiliensis enolase amino acid sequence. The data revealed that fibronectin is the major ligand of enolase. Evaluation of the location of enolase at an ultrastructural level revealed that it is distributed in various cellular compartments, but at a high level in the cell wall. The analysis of the amino acid sequence revealed an internal plasminogen-binding motif (254FYKADEKKY262), which is conserved in most organisms and described as an important interaction site of the enolase with the host cell surface. This suggests that enolase performs additional functions related to the glycolytic pathway and also plays a role of adhesion in P. brasiliensis. Therefore, this study increases the knowledge about the characteristics of enolase and its influence on the binding process of P. brasiliensis.
Anti-Immune Strategies of Pathogenic Fungi Marcos, Caroline M; de Oliveira, Haroldo C; de Melo, Wanessa de Cássia M Antunes ...
Frontiers in cellular and infection microbiology,
11/2016, Letnik:
6
Journal Article
Recenzirano
Odprti dostop
Pathogenic fungi have developed many strategies to evade the host immune system. Multiple escape mechanisms appear to function together to inhibit attack by the various stages of both the adaptive ...and the innate immune response. Thus, after entering the host, such pathogens fight to overcome the immune system to allow their survival, colonization and spread to different sites of infection. Consequently, the establishment of a successful infectious process is closely related to the ability of the pathogen to modulate attack by the immune system. Most strategies employed to subvert or exploit the immune system are shared among different species of fungi. In this review, we summarize the main strategies employed for immune evasion by some of the major pathogenic fungi.
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.
Despite the benefits in improving the clinical state of people living with HIV/aids (PLWHA), some side effects associated with the use of antiretroviral therapy (ART) are reported. Redistribution of ...body fat has been associated with treatment and is characterized by morphological changes, also known as lipodystrophy. The complications of metabolic and morphological changes in these individuals seem to increase the risk of cardiovascular disease. Adipocytokines are proteins that have essential functions in biological processes, in which the levels of these proteins are related to the pathogenesis of metabolic syndrome (MS) and cardiovascular disease. Recent studies have shown that such levels are generally modified in PLWHA, regardless of whether the treatment is established or not. An application of methods for body fat estimation in patients with fat redistribution, as in the case of aids, especially those that quantify body fat by segments, appears to clarify these alterations and plays an important role in the development of multiprofessional treatment.
This investigation was carried out to compare and correlate body composition, biochemical metabolic parameters, and levels of adipocytokines and cytokines of PLWHA, with and without lipodystrophy, with individuals with negative HIV serology and stratified by sex.
This is a cross-sectional study in which body composition, metabolic and anthropometric changes, and levels of adipocytokines of 110 individuals were assessed. These individuals were paired in sex, age, and body mass index (BMI) and subdivided into three groups: PLWHA with and without a clinical diagnosis of lipodystrophy associated with HIV, and a group control.
Collinearity was identified both in the general sample and for genders of the waist-to-height ratio (WHtR) with all anthropometric parameters, except for muscle mass. The results show strong association between IFN-γ and TNF-α both in the general sample and for genders and moderate correlation between leptin and fasting glucose for women; worsening of the triglyceride profile in both women with lipodystrophy compared with the control group and men without lipodystrophy compared with the control group; higher serum TNF-α values among men without lipodystrophy compared to those with HIV-associated lipodystrophy (HALS).
The results of this study underline that, considering the manifestations of the syndrome, these patients have a high-risk endocrine metabolic profile for cardiovascular events.
New drug delivery systems, such as nanoemulsions (NE), have been developed to allow the use of hydrophobic drugs on the antimicrobial photodynamic therapy. This study evaluated the photodynamic ...potential of aluminum‐chloride‐phthalocyanine (ClAlPc) entrapped in cationic and anionic NE to inactivate Candida albicans planktonic cultures and biofilm compared with free ClAlPc. Fungal suspensions were treated with different delivery systems containing ClAlPc and light emitting diode. For planktonic suspensions, colonies were counted and cell metabolism was evaluated by XTT assay. Flow cytometry evaluated cell membrane damage. For biofilms, the metabolic activity was evaluated by XTT and ClAlPc distribution through biofilms was analyzed by confocal laser scanning microscopy (CLSM). Fungal viability was dependent on the delivery system, superficial charge and light dose. Free ClAlPc caused photokilling of the yeast when combined with 100 J cm−2. Cationic NE‐ClAlPc reduced significantly both colony counts and cell metabolism (P < 0.05). In addition, cationic NE‐ClAlPc and free ClAlPc caused significant damage to the cell membrane (P < 0.05). For the biofilms, cationic NE‐ClAlPc reduced cell metabolism by 70%. Anionic NE‐ClAlPc did not present antifungal activity. CLSM showed different accumulation on biofilms between the delivery systems. Although NE system showed a lower activity for planktonic culture, cationic NE‐ClAlPc showed better results for Candida biofilms.
Candida albicans biofilm overview after 30 min of contact with free ClAlPc. This study presents the photodynamic potential of aluminum‐chloride‐phthalocyanine (ClAlPc) entrapped in cationic and anionic nanoemulsions (NE) to inactivate C. albicans planktonic cultures and biofilm comparing with free ClAlPc. The photodynamic effect was dependent on the delivery system, superficial charge and light dose. Cationic NE‐ClAlPc and free ClAlPc caused significant reduction in colony counts, cell metabolism and damage to the cell membrane (P < 0.05). However, only the free ClAlPc was able to cause photokilling of the yeast. The anionic NE‐ClAlPc did not present antifungal activity. Although NE system showed a lower activity for planktonic culture, cationic NE‐ClAlPc showed better results for Candida biofilms.
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