New advances in the development of a vaccine against paracoccidioidomycosis

Advances in Dendritic-Cell-Based Vaccines against Respiratory Fungal Infections

Ever since the discovery of dendritic cells by Ralph Steinman and Zanvil Cohn in 1973, it is increasingly evident that dendritic cells are integral for adaptive immune responses, and there is an undeniable focus on them for vaccines development. Fungal infections, often thought to be innocuous, are becoming significant threats due to an increased immunocompromised or immune-suppressed population and climate change. Further, the recent COVID-19 pandemic unraveled the wrath of fungal infections and devastating outcomes. Invasive fungal infections cause significant case fatality rates ranging from 20% to 90%. Regrettably, no licensed fungal vaccines exist, and there is an urgent need for preventive and therapeutic purposes. In this review, we discuss the ontogeny, subsets, tissue distribution, and functions of lung dendritic cells. In the latter part, we summarize and discuss the studies on the DC-based vaccines against pulmonary fungal infections. Finally, we highlight some emerging potential avenues that can be incorporated for DC-based vaccines against fungal infections.

Trends in the Epidemiological and Clinical Profile of Paracoccidioidomycosis in the Endemic Area of Rio de Janeiro, Brazil

Paracoccidioidomycosis (PCM) is a neglected endemic mycosis in Latin America. Most cases occur in Brazil. It is classified as PCM infection and PCM disease and is subdivided into chronic (adult type) or acute (juvenile type) disease, with the latter being less frequent and more severe. In 2016, we reported an increase in the numbers of patients diagnosed with acute PCM after a highway's construction. We conducted a study at INI-Fiocruz, a reference center for infectious diseases, including endemic mycoses, in Rio de Janeiro, Brazil, aiming to deepen the analysis of this new clinical and epidemiological profile of PCM. The authors developed a retrospective study including 170 patients diagnosed with PCM between 2010 and 2019. There was an increase in the number of atypical and severe forms, starting in 2014. In subsequent years, we detected a higher incidence of adverse outcomes with patients requiring more hospitalizations and an increased mortality rate. We estimate that PCM has become more severe throughout the Rio de Janeiro state, affecting a greater number of young individuals and leading to a greater number of and longer hospitalizations. Surveillance measures and close monitoring of future notification data in the state, with emphasis on children, adolescents, and young adults are necessary for a better understanding of the perpetuation of this public health challenge.

Targeting the P10 Peptide in Maturing Dendritic Cells via the DEC205 Receptor In Vivo: A New Therapeutic Strategy against Paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by Paracoccidioides brasiliensis, a thermally dimorphic fungus, which is the most frequent endemic systemic mycosis in many Latin American countries, where ~10 million people are believed to be infected. In Brazil, it is ranked as the tenth most common cause of death among chronic infectious diseases. Hence, vaccines are in development to combat this insidious pathogen. It is likely that effective vaccines will need to elicit strong T cell-mediated immune responses composed of IFNγ secreting CD4⁺ helper and CD8⁺ cytolytic T lymphocytes. To induce such responses, it would be valuable to harness the dendritic cell (DC) system of antigen-presenting cells. To assess the potential of targeting P10, which is a peptide derived from gp43 secreted by the fungus, directly to DCs, we cloned the P10 sequence in fusion with a monoclonal antibody to the DEC205 receptor, an endocytic receptor that is abundant on DCs in lymphoid tissues. We verified that a single injection of the αDEC/P10 antibody caused DCs to produce a large amount of IFNγ. Administration of the chimeric antibody to mice resulted in a significant increase in the levels of IFN-γ and IL-4 in lung tissue relative to control animals. In therapeutic assays, mice pretreated with αDEC/P10 had significantly lower fungal burdens compared to control infected mice, and the architecture of the pulmonary tissues of αDEC/P10 chimera-treated mice was largely normal. Altogether, the results obtained so far indicate that targeting P10 through a αDEC/P10 chimeric antibody in the presence of polyriboinosinic: polyribocytidylic acid is a promising strategy in vaccination and therapeutic protocols to combat PCM.

Biodistribution and Adjuvant Effect of an Intranasal Vaccine Based on Chitosan Nanoparticles against Paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is a fungal infection caused by the thermodimorphic Paracoccidioides sp. PCM mainly affects the lungs, but, if it is not contained by the immune response, the disease can spread systemically. An immune response derived predominantly from Th1 and Th17 T cell subsets facilitates the elimination of Paracoccidioides cells. In the present work, we evaluated the biodistribution of a prototype vaccine based on the immunodominant and protective P. brasiliensis P10 peptide within chitosan nanoparticles in BALB/c mice infected with P. brasiliensis strain 18 (Pb18). The generated fluorescent (FITC or Cy5.5) or non-fluorescent chitosan nanoparticles ranged in diameter from 230 to 350 nm, and both displayed a Z potential of +20 mV. Most chitosan nanoparticles were found in the upper airway, with smaller amounts localized in the trachea and lungs. The nanoparticles complexed or associated with the P10 peptide were able to reduce the fungal load, and the use of the chitosan nanoparticles reduced the necessary number of doses to achieve fungal reduction. Both vaccines were able to induce a Th1 and Th17 immune response. These data demonstrates that the chitosan P10 nanoparticles are an excellent candidate vaccine for the treatment of PCM.

Vaccine development for pathogenic fungi: current status and future directions

INTRODUCTION

Fungal infections are caused by a broad range of pathogenic fungi that are found worldwide with different geographic distributions, incidences, and mortality rates. Considering that there are relatively few approved medications available for combating fungal diseases and no vaccine formulation commercially available, multiple groups are searching for new antifungal drugs, examining drugs for repurposing and developing antifungal vaccines, in order to control deaths, sequels, and the spread of these complex infections.

AREAS COVERED

This review provides a summary of advances in fungal vaccine studies and the different approaches under development, such as subunit vaccines, whole organism vaccines, and DNA vaccines, as well as studies that optimize the use of adjuvants. We conducted a literature search of the PubMed with terms: fungal vaccines and genus of fungal pathogens (Cryptococcus spp. Candida spp. Coccidioides spp. Aspergillus spp. Sporothrix spp. Histoplasma spp. Paracoccidioides spp. Pneumocystis spp. and the Mucorales order), a total of 177 articles were collected from database.

EXPERT OPINION

Problems regarding the immune response development in an immunocompromised organism, the similarity between fungal and mammalian cells, and the lack of attention by health organizations to fungal infections are closely related to the fact that, at present, there are no fungal vaccines available for clinical use.

Paracoccidioidomycosis: Current Status and Future Trends

Paracoccidioidomycosis (PCM), initially reported in 1908 in the city of São Paulo, Brazil, by Adolpho Lutz, is primarily a systemic and neglected tropical mycosis that may affect individuals with certain risk factors around Latin America, especially Brazil. Paracoccidioides brasiliensis sensu stricto, a classical thermodimorphic fungus associated with PCM, was long considered to represent a monotypic taxon. However, advances in molecular taxonomy revealed several cryptic species, including Paracoccidioides americana, P. restrepiensis, P. venezuelensis, and P. lutzii, that show a preference for skin and mucous membranes, lymph nodes, and respiratory organs but can also affect many other organs. The classical diagnosis of PCM benefits from direct microscopy culture-based, biochemical, and immunological assays in a general microbiology laboratory practice providing a generic identification of the agents. However, molecular assays should be employed to identify Paracoccidioides isolates to the species level, data that would be complemented by epidemiological investigations. From a clinical perspective, all probable and confirmed cases should be treated. The choice of treatment and its duration must be considered, along with the affected organs, process severity, history of previous treatment failure, possibility of administering oral medication, associated diseases, pregnancy, and patient compliance with the proposed treatment regimen. Nevertheless, even after appropriate treatment, there may be relapses, which generally occur 5 years after the apparent cure following treatment, and also, the mycosis may be confused with other diseases. This review provides a comprehensive and critical overview of the immunopathology, laboratory diagnosis, clinical aspects, and current treatment of PCM, highlighting current issues in the identification, treatment, and patient follow-up in light of recent Paracoccidioides species taxonomic developments.

Natural-Product-Based Solutions for Tropical Infectious Diseases

About half of the world's population and 80% of the world's biodiversity can be found in the tropics. Many diseases are specific to the tropics, with at least 41 diseases caused by endemic bacteria, viruses, parasites, and fungi. Such diseases are of increasing concern, as the geographic range of tropical diseases is expanding due to climate change, urbanization, change in agricultural practices, deforestation, and loss of biodiversity. While traditional medicines have been used for centuries in the treatment of tropical diseases, the active natural compounds within these medicines remain largely unknown. In this review, we describe infectious diseases specific to the tropics, including their causative pathogens, modes of transmission, recent major outbreaks, and geographic locations. We further review current treatments for these tropical diseases, carefully consider the biodiscovery potential of the tropical biome, and discuss a range of technologies being used for drug development from natural resources. We provide a list of natural products with antimicrobial activity, detailing the source organisms and their effectiveness as treatment. We discuss how technological advancements, such as next-generation sequencing, are driving high-throughput natural product screening pipelines to identify compounds with therapeutic properties. This review demonstrates the impact natural products from the vast tropical biome have in the treatment of tropical infectious diseases and how high-throughput technical capacity will accelerate this discovery process.

Antibody- Based Immunotherapy Combined With Antimycotic Drug TMP- SMX to Treat Infection With Paracoccidioides brasiliensis

Monoclonal antibodies (mAbs) are promising alternatives to treat infectious diseases, especially given their potential for applications in combination therapies with antimicrobial drugs to enhance the antifungal efficacy. Protection mediated by mAbs used to treat experimental paracoccidioidomycosis (PCM) has been demonstrated previously. Our aim in the present work was to characterize a monoclonal antibody (mAbF1.4) raised against a cell wall glycoconjugate fraction of Paracoccidioides spp. and to analyze its efficacy combined with trimethoprim-sulfamethoxazole (TMP/SMX) as treatment for experimental PCM. We demonstrated that the epitope recognized by mAbF1.4 is consistent with branched glucose residues present on a cell wall β-glucan polymer. In vitro, mAbF1.4 increased the phagocytic capacity and nitric oxide concentration induced by the macrophage cell line J774.1A, and this resulted in a significant reduction in the viability of the opsonophagocytized yeasts. In vivo, we detected a significant reduction in pulmonary fungal burdens of mice treated with mAbF1.4 in association with TMP/SMX, which correlated with increased pulmonary concentrations (determined by ELISA) of IFN- γ, TNF-α, IL-10 and IL-17. In parallel, we observed a decrease in IL-4, suggesting that the treatment was associated with a mixed Th1-Th17 type immune response. Histopathology of lung segments from mice receiving the combination therapy showed a significant reduction in granulomas, which were well-defined, and improved maintenance of lung architecture. These findings demonstrate that mAbF1.4 + TMP/SMX therapy is a promising approach to combat PCM as well as decrease disease sequelae and highlights the potential benefits of immune mediators in PCM combined immunotherapy.

Neutrophil Cells Are Essential for The Efficacy of a Therapeutic Vaccine against Paracoccidioidomycosis

Paracoccidioidomycosis (PCM), caused by the Paracoccidioides species, is a systemic disease endemic in several Latin American countries, mainly in Brazil, Colombia, Argentina, and Venezuela. Current treatment approaches are challenging as they require prolonged durations of antifungal drugs that have potential toxicities, and despite antifungals, relapses are common. Hence, new therapeutic approaches, such as vaccines, are being investigated. The therapeutic vaccine consisting of peptide P10 associated with lipid cationic DODAB (P10+DODAB) is effective in murine models of PCM. However, the specific immune mechanisms required for the protective response has not been fully elucidated. The present work aims at evaluating the participation of neutrophils in the immune response induced by P10+DODAB. We found that the vaccine reduced both the influx of pulmonary neutrophils and the fungal load in comparison to infected animals that did not receive this treatment. The parenchymal architecture of the lungs of P10+DODAB-treated animals was largely preserved with only a few granulomas present, and tissue cytokine analysis showed a Th1 cytokine profile with augmented levels of IL-12, IFN-γ and TNF-α, and low levels of IL-4. When neutrophils were depleted 24 h prior to each treatment, the effectiveness of the P10+DODAB vaccine was completely lost as the fungal burdens remained high and histological examination showed a marked inflammation and fungal dissemination with a dysregulated cytokine response. In conclusion, these findings indicate that neutrophils are vital to ensure the triggering of an effective immune response to P10+DODAB.

Immunotherapy against Systemic Fungal Infections Based on Monoclonal Antibodies

The increasing incidence in systemic fungal infections in humans has increased focus for the development of fungal vaccines and use of monoclonal antibodies. Invasive mycoses are generally difficult to treat, as most occur in vulnerable individuals, with compromised innate and adaptive immune responses. Mortality rates in the setting of our current antifungal drugs remain excessively high. Moreover, systemic mycoses require prolonged durations of antifungal treatment and side effects frequently occur, particularly drug-induced liver and/or kidney injury. The use of monoclonal antibodies with or without concomitant administration of antifungal drugs emerges as a potentially efficient treatment modality to improve outcomes and reduce chemotherapy toxicities. In this review, we focus on the use of monoclonal antibodies with experimental evidence on the reduction of fungal burden and prolongation of survival in in vivo disease models. Presently, there are no licensed monoclonal antibodies for use in the treatment of systemic mycoses, although the potential of such a vaccine is very high as indicated by the substantial promising results from several experimental models.

Novel 4-methoxynaphthalene-N-acylhydrazones as potential for paracoccidioidomycosis and tuberculosis co-infection

Aim: 17 new 4-methoxynaphthalene-N-acylhydrazones were synthesized in order to evaluate their biological action against important pathogens. Methods: In vitro susceptibility assays of compounds were performed against Paracoccidioides brasiliensis and Mycobacterium tuberculosis. Results: Compounds 4a, 4b and 4k were the most potent against P. brasiliensis, two with minimum inhibitory concentrations of ≤1 μg ml^-1 and exhibited pharmacological synergy with amphotericin B. The compounds also showed activity against M. tuberculosis, with 4c and 4k being the more promising. Compound 4k showed good synergistic antimycobacterium activity with ethambutol. None of the compounds tested showed toxicity. Conclusion: We highlight the compound 4k, as a potential agent for the treatment of patients co-infected with paracoccidioidomycosis and tuberculosis.

Thiosemicarbazone of lapachol acts on cell membrane in Paracoccidioides brasiliensis

Paracoccidioidomycosis (PCM) is the most prevalent systemic mycosis in Latin American countries. Amphotericin B, sulfonamides, and azoles may be used in the treatment of PCM. However, the high toxicity, prolonged course of treatment, and significant frequency of disease relapse compromise their use. Therefore, there is a need to seek new therapeutic options. We conducted tests with thiosemicarbazone of lapachol (TSC-lap) to determine the antifungal activity and phenotypic effects against several isolates of Paracoccidioides spp. In addition, we evaluated the toxicity against murine macrophages and the ability to enhance phagocytosis. Further, we verified that TSC-lap was active against yeasts but did not show any interaction with the drugs tested. The TSC-lap showed no toxicity at the concentration of 40 μg/ml in macrophages, and at 15.6 μg/ml it could increase the phagocytic index. We observed that this compound induced in vitro ultrastructural changes manifested as withered and broken cells beyond a disorganized cytoplasm with accumulation of granules. We did not observe indications of activity in the cell wall, although membrane damages were noted. We observed alterations in the membrane permeability, culminating in a significant increase in K+ efflux and a gradual loss of the cellular content with increase in the concentration of TSC-lap. In addition, we showed a significant reduction of ergosterol amount in the Pb18 membrane. These data reinforce the possible mechanism of action of this compound to be closely associated with ergosterol biosynthesis and reaffirms the antifungal potential of TSC-lap against Paracoccidioides spp.

Heat Shock Proteins in Histoplasma and Paracoccidioides

Heat shock proteins (Hsps) are highly conserved biomolecules that are constitutively expressed and generally upregulated in response to various stress conditions (biotic and abiotic). Hsps have diverse functions, categorizations, and classifications. Their adaptive expression in fungi indicates their significance in these diverse species, particularly in dimorphic pathogens. Histoplasma capsulatum and Paracoccidioides species are dimorphic fungi that are the causative agents of histoplasmosis and paracoccidioidomycosis, respectively. This minireview focuses on the pathobiology of Hsps, with particular emphasis on their roles in the morphogenesis and virulence of Histoplasma and Paracoccidioides and the potential roles of active and passive immunization against Hsps in protection against infection with these fungi.

Paracoccidioidomycosis: level of pulmonary sequelae in high resolution computed tomography images from patients of two endemic regions of Brazil

BACKGROUND

The purpose of the present study was to evaluate differences in lung damage in patients with paracoccidioidomycosis (PCM) in two endemic regions of Brazil (Botucatu, SP, in the southeastern region and Campo Grande, MS, in the west central region).

METHODS

The study sought to objectively quantify fibrosis and emphysema treated patients using high-resolution computed tomography (HRCT) that was performed according to an established and validated computational method. The analysis was based on clinical data that were associated with objective quantifications of pulmonary sequelae. We performed a retrospective analysis of HRCT exams from 32 successfully treated patients with the chronic form of PCM. The two groups had similar characteristics with regard to age, symptom duration, smoking history, and titers on a diagnostic serologic test.

RESULTS

The statistical analysis revealed more severe cases and a higher percentage of emphysema in the Campo Grande group. The mean percentages of emphysema were 40.2% and 13.6% in the Campo Grande and Botucatu groups, respectively. The percentage of fibrosis was significantly higher in the Botucatu group (11.3%) than in the Campo Grande group (2.3%).

CONCLUSIONS

The present results may reflect differences in cryptic species of P. brasiliensis in these two geographic regions of Brazil. Further studies should be done to clarify the differences observed herein. Such findings may help unveil differences among cryptic species in terms of the pulmonary consequences that are caused by this disease, which would be highly beneficial to PCM patients.

Antifungal and antioxidant activity of fatty acid methyl esters from vegetable oils

Fatty acid methyl esters (FAMEs) were obtained from vegetable oils of soybean, corn and sunflower. The current study was focused on evaluating the antifungal activity of FAMEs mainly against Paracoccidioides spp., as well as testing the interaction of these compounds with commercial antifungal drugs and also their antioxidant potential. FAMEs presented small IC50 values (1.86-9.42 μg/mL). All three FAMEs tested showed antifungal activity against isolates of Paracoccidioides spp. with MIC values ranging from 15.6-500 µg/mL. Sunflower FAMEs exhibited antifungal activity that extended also to other genera, with an MIC of 15.6 μg/mL against Candida glabrata and C. krusei and 31.2 μg/mL against C. parapsilosis. FAMEs exhibited a synergetic effect with itraconazole. The antifungal activity of the FAMEs against isolates of Paracoccidioides spp. is likely due to the presence of methyl linoleate, the major compound present in all three FAMEs. The results obtained indicate the potential of FAMEs as sources for antifungal and antioxidant activity.

Dendritic Cells Primed with Paracoccidioides brasiliensis Peptide P10 Are Therapeutic in Immunosuppressed Mice with Paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is an endemic systemic mycosis in Latin America, with the highest prevalence in Brazil, Colombia, and Venezuela. Fungi of the Paracoccidioides genus are etiologic agents of the disease. The 15 amino acid peptide P10 is derived from gp43, the main diagnostic antigen of Paracoccidioides brasiliensis. We previously reported that P10-pulsed dendritic cells (DCs) induce a protective response against P. brasiliensis. Presently, dexamethasone-treated BALB/c mice were intratracheally infected with P. brasiliensis Pb18 to establish the therapeutic efficacy of P10-pulsed DCs. Immunosuppressed and infected animals that received DCs had a reduction in their fungal burden, and this result was most pronounced in mice receiving DCs primed with P10. The efficacy of therapeutic DCs was significantly augmented by concomitant treatment with trimethoprim-sulfamethoxazole. Additionally, primed-DCs with or without the antifungal drug induced a beneficial Th₁-biased immune response and significantly reduced tissue damage. In conclusion, these studies with immunocompromised mice demonstrate that P10-pulsed DCs with or without concomitant antifungal drugs are potently effective in combating invasive PCM. These findings support further translational studies to validate the use of P10-primed DCs for PCM in immunocompetent and immunosuppressed hosts.

Peptides Derived from a Phage Display Library Inhibit Adhesion and Protect the Host against Infection by Paracoccidioides brasiliensis and Paracoccidioides lutzii

Paracoccidioides brasiliensis and Paracoccidioides lutzii are dimorphic fungi and are the etiological agents of paracoccidioidomycosis (PCM). Adhesion is one of the most important steps in infections with Paracoccidioides and is responsible for the differences in the virulence of isolates of these fungi. Because of the importance of adhesion to the establishment of an infection, this study focused on the preliminary development of a new therapeutic strategy to inhibit adhesion by Paracoccidioides, thus inhibiting infection and preventing the disease. We used two phage display libraries to select peptides that strongly bind to the Paracoccidioides cell wall to inhibit adhesion to host cells and extracellular matrix (ECM) components (laminin, fibronectin, and type I and type IV collagen). This approach allowed us to identify four peptides that inhibited up to 64% of the adhesion of Paracoccidioides to pneumocytes in vitro and inhibited the adhesion to the ECM components by up to 57%. Encouraged by these results, we evaluated the ability of these peptides to protect Galleria mellonella from Paracoccidioides infection by treating G. mellonella larvae with the different peptides prior to infection with Paracoccidioides and observing larval survival. The results show that all of the peptides tested increased the survival of the larvae infected with P. brasiliensis by up to 64% and by up to 60% in those infected with P. lutzii. These data may open new horizons for therapeutic strategies to prevent PCM, and anti-adhesion therapy could be an important strategy.

Antifungal activity of extracts from Atacama Desert fungi against Paracoccidioides brasiliensis and identification of Aspergillus felis as a promising source of natural bioactive compounds

Fungi of the genus Paracoccidioides are responsible for paracoccidioidomycosis. The occurrence of drug toxicity and relapse in this disease justify the development of new antifungal agents. Compounds extracted from fungal extract have showing antifungal activity. Extracts of 78 fungi isolated from rocks of the Atacama Desert were tested in a microdilution assay against Paracoccidioides brasiliensis Pb18. Approximately 18% (5) of the extracts showed minimum inhibitory concentration (MIC) values≤ 125.0 µg/mL. Among these, extract from the fungus UFMGCB 8030 demonstrated the best results, with an MIC of 15.6 µg/mL. This isolate was identified as Aspergillus felis (by macro and micromorphologies, and internal transcribed spacer, β-tubulin, and ribosomal polymerase II gene analyses) and was grown in five different culture media and extracted with various solvents to optimise its antifungal activity. Potato dextrose agar culture and dichloromethane extraction resulted in an MIC of 1.9 µg/mL against P. brasiliensis and did not show cytotoxicity at the concentrations tested in normal mammalian cell (Vero). This extract was subjected to bioassay-guided fractionation using analytical C18RP-high-performance liquid chromatography (HPLC) and an antifungal assay using P. brasiliensis. Analysis of the active fractions by HPLC-high resolution mass spectrometry allowed us to identify the antifungal agents present in the A. felis extracts cytochalasins. These results reveal the potential of A. felis as a producer of bioactive compounds with antifungal activity.

PARACOCCIDIOIDOMYCOSIS: CHALLENGES IN THE DEVELOPMENT OF A VACCINE AGAINST AN ENDEMIC MYCOSIS IN THE AMERICAS

Paracoccidioidomycosis (PCM), caused by Paracoccidioides spp, is an important endemic mycosis in Latin America. There are two recognized Paracoccidioides species, P. brasiliensis and P. lutzii, based on phylogenetic differences; however, the pathogenesis and disease manifestations of both are indistinguishable at present. Approximately 1,853 (~51,2%) of 3,583 confirmed deaths in Brazil due to systemic mycoses from 1996-2006 were caused by PCM. Antifungal treatment is required for patients with PCM. The initial treatment lasts from two to six months and sulfa derivatives, amphotericin B, azoles and terbinafine are used in clinical practice; however, despite prolonged therapy, relapses are still a problem. An effective Th1-biased cellular immune response is essential to control the disease, which can be induced by exogenous antigens or modulated by prophylactic or therapeutic vaccines. Stimulation of B cells or passive transference of monoclonal antibodies are also important means that may be used to improve the efficacy of paracoccidioidomycosis treatment in the future. This review critically details major challenges facing the development of a vaccine to combat PCM.

Antibodies Against Glycolipids Enhance Antifungal Activity of Macrophages and Reduce Fungal Burden After Infection with Paracoccidioides brasiliensis

Paracoccidioidomycosis is a fungal disease endemic in Latin America. Polyclonal antibodies to acidic glycosphingolipids (GSLs) from Paracoccidioides brasiliensis opsonized yeast forms in vitro increasing phagocytosis and reduced the fungal burden of infected animals. Antibodies to GSL were active in both prophylactic and therapeutic protocols using a murine intratracheal infection model. Pathological examination of the lungs of animals treated with antibodies to GSL showed well-organized granulomas and minimally damaged parenchyma compared to the untreated control. Murine peritoneal macrophages activated by IFN-γ and incubated with antibodies against acidic GSLs more effectively phagocytosed and killed P. brasiliensis yeast cells as well as produced more nitric oxide compared to controls. The present work discloses a novel target of protective antibodies against P. brasiliensis adding to other well-studied mediators of the immune response to this fungus.

Antifungal activity of 6-quinolinyl N-oxide chalcones against Paracoccidioides

BACKGROUND

Chalcones are an important class of natural compounds that have been widely applied as synthons in synthetic organic chemistry and possess diverse and interesting biological properties.

METHODS

We conducted tests with the synthetic substances 6-quinolinyl N-oxide chalcones 4c and 4e to determine their antifungal activity against several isolates of Paracoccidioides spp. and their activity in a murine model. We also determined whether the chalcones interacted with other drugs or interfered with the morphology of Paracoccidioides brasiliensis (Pb18) yeast cells.

RESULTS

We verified that the substances were active against Paracoccidioides spp., but we did not show an interaction with the drugs tested when only the fractional inhibitory concentration index values were considered individually. We observed that the substances induced in vitro morphological changes. Compounds 4c and 4e showed activity similar to itraconazole in treated mice, as demonstrated by their ability to reduce the number of cfu recovered from the lungs. Histopathological analysis showed that animals treated with 4c presented fewer areas containing inflammatory infiltrate and larger areas of preserved lung tissue, whereas animals treated with itraconazole showed accumulation of inflammatory infiltrate and some granulomas. Mice treated with 4e exhibited inflammation that compromised the tissue.

CONCLUSIONS

The results presented in this paper confirm the antifungal potential of the chalcones tested. The chalcone 4c was the more effective at controlling the disease in mice and this compound could be a candidate for future studies of the treatment of paracoccidioidomycosis.

Monoclonal antibodies to heat shock protein 60 induce a protective immune response against experimental Paracoccidioides lutzii

Paracoccidioidomycosis (PCM) is an endemic mycosis in Latin America. PCM is primarily caused by Paracoccidioides brasiliensis and less frequently by the recently described, closely related species Paracoccidioides lutzii. Current treatment requires protracted administration of systemic antibiotics and relapses may frequently occur despite months of initial therapy. Hence, there is a need for innovative approaches to treatment. In the present study we analyzed the impact of two monoclonal antibodies (mAbs) generated against Heat Shock 60 (Hsp60) from Histoplasma capsulatum on the interactions of P. lutzii with macrophages and on the experimental P. lutzii infection. We demonstrated that the Hsp60-binding mAbs labeled P. lutzii yeast cells and enhanced their phagocytosis by macrophage cells. Treatment of mice with the mAbs to Hsp60 before infection reduced the pulmonary fungal burden as compared to mice treated with irrelevant mAb. Hence, mAbs raised to H. capsulatum Hsp60 are protective against P. lutzii, including mAb 7B6 which was non-protective against H. capsulatum, suggesting differences in their capacity to bind to these fungi and to be recognized by macrophages. These findings indicate that mAbs raised to one dimorphic fungus may be therapeutic against additional dimorphic fungi, but also suggests that biological differences in diseases may influence whether a mAb is beneficial or harmful.

Endemic mycoses in immunocompromised hosts

Endemic mycoses remain a significant cause of morbidity and mortality among immunocompromised patients. As the number of immunosuppressed individuals increases worldwide, the incidence of endemic mycoses is also expected to rise. In immunocompromised patients, endemic mycoses can present in atypical fashion, cause more severe and/or disseminated disease, and result in higher mortality. Despite several noteworthy advances over the past decade, significant challenges remain with regard to the prevention, diagnosis, and therapy of endemic mycoses in immunocompromised hosts. This review highlights important developments related to the epidemiology, diagnosis, treatment, and prevention of commonly encountered endemic mycoses. We also discuss emerging topics, knowledge gaps, and areas of future research.

Important aspects of oral paracoccidioidomycosis--a literature review

Paracoccidioidomycosis is a deep mycosis endemic to Latin America, with considerable morbidity and mortality. It is caused by the dimorphic fungus Paracoccidioides brasiliensis, which affects, among other organs in the human body, the oral cavity. Fungus virulence and immunocompetence of the host determine the establishment of infection or active disease, whose severity and clinical behaviour depend mostly on the cellular immune response of the host. Often, oral lesions constitute the first sign and site of confirmation of diagnosis, which in most cases is delayed. The success of the treatment depends on early and correct diagnosis, as well as on the patient's adherence to the drug therapy.

Paracoccidioidomycosis vaccine

Paracoccidioidomycosis is a granulomatous pulmonary infection that is generally controlled by chemotherapy. The efficacy of treatment, however, is limited by the status of the host immune response. The inhibition of a Th-2 immunity or the stimulation of Th-1 cytokines generally increases the efficacy of antifungal drugs. ( 1) This has been achieved by immunization with an internal peptide of the major diagnostic antigen gp43 of Paracoccidioides brasiliensis. Peptide 10 (QTLIAIHTLAIRYAN) elicits an IFN-γ rich Th-1 immune response that protects against experimental intratracheal infection by this fungus. The combination of chemotherapy with P10 immunization showed additive protective effect even after 30 d of infection or in anergic mice, rendering in general, increased production of IL-12 and IFN-γ and reduction of IL-4 and IL-10. Immunotherapy with P10 even in the absence of simultaneous chemotherapy has been effective using various protocols, adjuvants, nanoparticles, P10-primed dendritic cells, and especially a combination of plasmids encoding the P10 minigene and IL-12. Gene therapy, in a long-term infection protocol succeeded in the virtual elimination of the fungus, preserving the lung structure, free from immunopathological side effects.