The filamentous fungus Lomentospora (Scedosporium) prolificans is an emerging opportunistic pathogen associated with fatal infections in patients with disturbed immune function. Unfortunately, ...conventional therapies are hardly of any use against this fungus due to its intrinsic resistance. Therefore, we performed an integrated study of the L. prolificans responses to the first option to treat these mycoses, namely voriconazole, with the aim of unveiling mechanisms involved in the resistance to this compound. To do that, we used a wide range of techniques, including fluorescence and electron microscopy to study morphological alterations, ion chromatography to measure changes in cell-wall carbohydrate composition, and proteomics-based techniques to identify the proteins differentially expressed under the presence of the drug. Significantly, we showed drastic changes occurring in cell shape after voriconazole exposure, L. prolificans hyphae being shorter and wider than under control conditions. Interestingly, we proved that the architecture and carbohydrate composition of the cell wall had been modified in the presence of the drug. Specifically, L. prolificans constructed a more complex organelle with a higher presence of glucans and mannans. In addition to this, we identified several differentially expressed proteins, including Srp1 and heat shock protein 70 (Hsp70), as the most overexpressed under voriconazole-induced stress conditions. The mechanisms described in this study, which may be directly related to L. prolificans antifungal resistance or tolerance, could be used as targets to improve existing therapies or to develop new ones in order to successfully eliminate these mycoses.
Candida albicans is a commensal yeast able to cause life threatening invasive infections particularly in immunocompromised patients. Despite the availability of antifungal treatments, mortality rates ...are still unacceptably high and drug resistance is increasing. We, therefore, generated the Ca37 monoclonal antibody against the C. albicans alcohol dehydrogenase (Adh) 1. Our data showed that Ca37 was able to detect C. albicans cells, and it bound to Adh1 in yeast and Adh2 in hyphae among the cell wall-associated proteins. Moreover, Ca37 was able to inhibit candidal growth following 18 h incubation time and reduced the minimal inhibitory concentration of amphotericin B or fluconazole when used in combination with those antifungals. In addition, the antibody prolonged the survival of C. albicans infected-Galleria mellonella larvae, when C. albicans was exposed to antibody prior to inoculating G. mellonella or by direct application as a therapeutic agent on infected larvae. In conclusion, the Ca37 monoclonal antibody proved to be effective against C. albicans, both in vitro and in vivo, and to act together with antifungal drugs, suggesting Adh proteins could be interesting therapeutic targets against this pathogen.
The detection and diagnosis of the opportunistic fungi
spp. and
still relies mainly on low-sensitive culture-based methods. This fact is especially worrying in Cystic Fibrosis (CF) patients in whom ...these fungal species are frequently isolated and may increase the risk of suffering from an infection or other health problems. Therefore, with the purpose of developing a serologic detection method for
/
, four different
protein extracts (whole cell protein extract, secretome, total cell surface and conidial surface associated proteins) were studied by ELISA to select the most useful for IgG detection in sera from CF patients. The four extracts were able to discriminate the
/
-infected from
infected and non-infected patients. However, the whole cell protein extract was the one selected, as it was the one with the highest output in terms of protein concentration per ml of fungal culture used, and its discriminatory capacity was the best. The ELISA test developed was then assayed with 212 sera from CF patients and it showed to be able to detect
spp. and
with very high sensitivity and specificity, 86%-100% and 93%-99%, respectively, depending on the cut-off value chosen (four values were proposed A
= 0.5837, A
= 0.6042, A
= 0.6404, and A
= 0.7099). Thus, although more research is needed to reach a standardized method, this ELISA platform offers a rapid, low-cost and easy solution to detect these elusive fungi through minimally invasive sampling, allowing the monitoring of the humoral response to fungal presence.
The detection of
/
is still based on non-standardized low-sensitivity culture procedures. This fact is particularly worrying in patients with cystic fibrosis (CF), where these fungi are the second ...most common filamentous fungi isolated, because a poor and delayed diagnosis can worsen the prognosis of the disease. To contribute to the discovery of new diagnostic strategies, a rapid serological dot immunobinding assay (DIA) that allows the detection of serum IgG against
/
in less than 15 min was developed. A crude protein extract from the conidia and hyphae of
was employed as a fungal antigen. The DIA was evaluated using 303 CF serum samples (162 patients) grouped according to the detection of
/
in the respiratory sample by culture, obtaining a sensitivity and specificity of 90.48% and 79.30%, respectively; positive and negative predictive values of 54.81% and 96.77%, and an efficiency of 81.72%. The clinical factors associated with the results were also studied using a univariate and a multivariate analysis, which showed that
/
positive sputum, elevated anti-
serum IgG and chronic
infection were significantly associated with a positive result in DIA, while
positive sputum showed a negative association. In conclusion, the test developed can offer a complementary, rapid, simple and sensitive method to contribute to the diagnosis of
/
in patients with CF.
Infections caused by the opportunistic pathogens
/
are on the rise. This causes problems in the clinic due to the difficulty in diagnosing and treating them. This review collates information ...published on immune response against these fungi, since an understanding of the mechanisms involved is of great interest in developing more effective strategies against them.
/
cell wall components, including peptidorhamnomannans (PRMs), α-glucans and glucosylceramides, are important immune response activators following their recognition by TLR2, TLR4 and Dectin-1 and through receptors that are yet unknown. After recognition, cytokine synthesis and antifungal activity of different phagocytes and epithelial cells is species-specific, highlighting the poor response by microglial cells against
. Moreover, a great number of
/
antigens have been identified, most notably catalase, PRM and Hsp70 for their potential medical applicability. Against host immune response, these fungi contain evasion mechanisms, inducing host non-protective response, masking fungal molecular patterns, destructing host defense proteins and decreasing oxidative killing. In conclusion, although many advances have been made, many aspects remain to be elucidated and more research is necessary to shed light on the immune response to
/
.
The liver, and more specifically, the liver sinusoidal endothelial cells, constitute the beginning of one of the most important responses for the elimination of hematogenously disseminated Candida ...albicans. Therefore, we aimed to study the mechanisms involved in the interaction between these cells and C. albicans. Transcriptomics-based analysis showed an increase in the expression of genes related to the immune response (including receptors, cytokines, and adhesion molecules), as well as to aerobic glycolysis. Further in vitro analyses showed that IL-6 production in response to C. albicans is controlled by MyD88- and SYK-pathways, suggesting an involvement of Toll-like and C-type lectin receptors and the subsequent activation of the MAP-kinases and c-Fos/AP-1 transcription factor. In addition, liver sinusoidal endothelial cells undergo metabolic reprogramming towards aerobic glycolysis induced by C. albicans, as confirmed by the increased Extracellular Acidification Rate and the overexpression of enolase (Eno2), hexonikase (Hk2) and glucose transporter 1 (Slc2a1). In conclusion, these results indicate that the hepatic endothelium responds to C. albicans by increasing aerobic glycolysis and promoting an inflammatory environment.
The delay in making a correct diagnosis of Candida auris causes concern in the healthcare system setting, and immunoproteomics studies are important to identify immunoreactive proteins for new ...diagnostic strategies. In this study, immunocompetent murine systemic infections caused by non-aggregative and aggregative phenotypes of C. auris and by Candida albicans and Candida haemulonii were carried out, and the obtained sera were used to study their immunoreactivity against C. auris proteins. The results showed higher virulence, in terms of infection signs, weight loss, and histopathological damage, of the non-aggregative isolate. Moreover, C. auris was less virulent than C. albicans but more than C. haemulonii. Regarding the immunoproteomics study, 13 spots recognized by sera from mice infected with both C. auris phenotypes and analyzed by mass spectrometry corresponded to enolase, phosphoglycerate kinase, glyceraldehyde-3-phosphate dehydrogenase, and phosphoglycerate mutase. These four proteins were also recognized by sera obtained from human patients with disseminated C. auris infection but not by sera obtained from mice infected with C. albicans or Aspergillus fumigatus. Spot identification data are available via ProteomeXchange with the identifier PXD049077. In conclusion, this study showed that the identified proteins could be potential candidates to be studied as new diagnostic or even therapeutic targets for C. auris.
Abstract
Species of Scedosporium and Lomentospora are considered as emerging opportunists, affecting immunosuppressed and otherwise debilitated patients, although classically they are known from ...causing trauma-associated infections in healthy individuals. Clinical manifestations range from local infection to pulmonary colonization and severe invasive disease, in which mortality rates may be over 80%. These unacceptably high rates are due to the clinical status of patients, diagnostic difficulties, and to intrinsic antifungal resistance of these fungi. In consequence, several consortia have been founded to increase research efforts on these orphan fungi. The current review presents recent findings and summarizes the most relevant points, including the Scedosporium/Lomentospora taxonomy, environmental distribution, epidemiology, pathology, virulence factors, immunology, diagnostic methods, and therapeutic strategies.
Abstract
The most common genetic hereditary disease affecting Caucasians is cystic fibrosis (CF), which is caused by autosomal recessive mutations in the CFTR gene. The most serious consequence is ...the production of a thick and sticky mucus in the respiratory tract, which entraps airborne microorganisms and facilitates colonization, inflammation and infection. Therefore, the present article compiles the information about the microbiota and, particularly, the inter-kingdom fungal-bacterial interactions in the CF lung, the molecules involved and the potential effects that these interactions may have on the course of the disease. Among the bacterial compounds, quorum sensing-regulated molecules such as homoserine lactones, phenazines, rhamnolipids, quinolones and siderophores (pyoverdine and pyochelin) stand out, but volatile organic compounds, maltophilin and CF-related bacteriophages are also explained. These molecules exhibit diverse antifungal mechanisms, including iron starvation and induction of reactive oxygen and nitrogen species production. The fungal compounds are less studied, but they include cell wall components, siderophores, patulin and farnesol. Despite the apparent competition between microorganisms, the persistence of significant rates of bacterial-fungal co-colonization in CF suggests that numerous variables influence it. In conclusion, it is crucial to increase scientific and economic efforts to intensify studies on the bacterial-fungal inter-kingdom interactions in the CF lung.
This review describes fungal-bacterial interactions and their effects on the respiratory tract of cystic fibrosis patients.
•Antifungal resistance is an increasingly relevant problem.•Molecular mechanisms underlying antifungal resistance are not yet fully understood.•Emerging fungi such as Lomentospora prolificans are ...inherently resistant, representing therapeutic challenges.•Regarding its pathobiology, L. prolificans might serve as a model for studying antifungal resistance.
The number of fungal isolates resistant to antifungal drugs has increased dramatically over the last few years and has become an important concern for clinicians. Among these isolates, fungi showing multidrug resistance are particularly worrying because of the difficulties associated with their treatment. These factors hamper the successful recovery of patients and drastically raise mortality rates. Antifungal resistance is multifactorial and several mechanisms in different fungi have been described. There is a need to study these mechanisms in depth; however, the study of antifungal drug resistance separately for each individual species makes progress in the field very slow and tedious. The selection of a multiresistant microorganism as a model for understanding resistance mechanisms and extrapolating the results to other species could help in the search for a solution. In this mini-review, we describe the pathobiology of Lomentospora (Scedosporium) prolificans, paying special attention to its intrinsic resistance to all currently available antifungal agents. The characteristics of L. prolificans offer several advantages: the possibility of using a single microorganism for the study of resistance to different drugs, even cases of double and triple resistance; it is biologically safe for society in general as no new genetically–modified strains are needed for the experiments; it is homologous with other fungal species, and there is repetitiveness between different strains. In conclusion, we propose L. prolificans as a candidate for consideration as a fungal model for the study of resistance mechanisms against antifungal agents.
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