The Th2 Response and Alternative Activation of Macrophages Triggered by Strongyloides venezuelensis Is Linked to Increased Morbidity and Mortality Due to Cryptococcosis in Mice

Cryptococcosis is a systemic mycosis that causes pneumonia and meningoencephalitis. Strongyloidiasis is a chronic gastrointestinal infection caused by parasites of the genus Strongyloides. Cryptococcosis and strongyloidiasis affect the lungs and are more prevalent in the same world regions, i.e., Africa and tropical countries such as Brazil. It is undeniable that those coincidences may lead to the occurrence of coinfections. However, there are no studies focused on the interaction between Cryptococcus spp. and Strongyloides spp. In this work, we aimed to investigate the interaction between Strongyloides venezuelensis (Sv) and Cryptococcus gattii (Cg) in a murine coinfection model. Murine macrophage exposure to Sv antigens reduced their ability to engulf Cg and produce reactive oxygen species, increasing the ability of fungal growth intracellularly. We then infected mice with both pathogens. Sv infection skewed the host's response to fungal infection, increasing lethality in a murine coinfection model. In addition to increased NO levels and arginase activity, coinfected mice presented a classic Th2 anti-Sv response: eosinophilia, higher levels of alternate activated macrophages (M2), increased concentrations of CCL24 and IL-4, and lower levels of IL-1β. This milieu favored fungal growth in the lungs with prominent translocation to the brain, increasing the host's tissue damage. In conclusion, our data shows that primary Sv infection promotes Th2 bias of the pulmonary response to Cg-infection and worsens its pathological outcomes.

Tumour necrosis factor plays a deleterious role in the pathogenesis of chikungunya virus infection

Arthralgia is a hallmark of chikungunya virus (CHIKV) infection and can be very debilitating and associated with a robust local inflammatory response. Many pathophysiological aspects associated with the disease remain to be elucidated. Here, we describe a novel model of CHIKV infection in immunocompetent mice and evaluate the role of tumour necrosis factor in the pathogenesis of the disease. C57BL/6 wild type (WT) or TNF receptor 1 deficient (TNFR1^-/- ) mice were inoculated with 1 × 10⁶ PFU of CHIKV in the paw. Alternatively, etanercept was used to inhibit TNF in infected WT mice. Hypernociception, inflammatory and virological analysis were performed. Inoculation of CHIKV into WT mice induced persistent hypernociception. There was significant viral replication in target organs and local production of inflammatory mediators in early time-points after infection. CHIKV infection was associated with specific humoral IgM and IgG responses. In TNFR1^-/- mice, there was a decrease in the hypernociception threshold, which was associated with a milder local inflammatory response in the paw but delayed viral clearance. Local or systemic treatment with etanercept reduced CHIKV-induced hypernociception. This is the first study to describe hypernociception, a clinical correlation of arthralgia, in immunocompetent mice infected with CHIKV. It also demonstrates the dual role of TNF in contributing to viral clearance but driving tissue damage and hypernociception. Inhibition of TNF may have therapeutic benefits but its role in viral clearance suggests that viral levels must be monitored in CHIKV-infected patients and that TNF inhibitors should ideally be used in combination with anti-viral drugs.

Investigating potential associations between neurocognition/social cognition and oxidative stress in schizophrenia

INTRODUCTION

Deficits in neurocognition and social cognition play a critical role in the functional impairment of patients with schizophrenia. Increased oxidative stress has been evidenced in schizophrenia. Increased oxidative stress can affect neuronal function and lead to impairments in neurocognitive functions (especially working memory) and social cognition.

OBJECTIVE

To investigate deficits in neurocognition and social cognition and their potential association with oxidative stress biomarkers in schizophrenia.

MATERIAL AND METHODS

Eight-five clinically stable patients with schizophrenia and 75 controls were enrolled in this study. Neurocognition was evaluated through the Brief Assessment of Cognition in Schizophrenia (BACS). Social cognition was assessed through the Hinting Task - a test of theory of mind - and an emotion processing test, Facial Emotion Recognition Test (FERT-100). Oxidative stress was assessed by measuring serum levels of glutathione (GSH) and thiobarbituric acid reactive substances (TBARS).

RESULTS

Patients had decreased serum levels of GSH (Z=3.56; p<0.001) and increased TBARS (Z=5.51; P<0.001) when compared with controls. TBARS levels are higher in patients using first generation antipsychotics. Higher serum levels of TBARS in patients were associated with poor performance in working memory test (r=-0.39; p=0.002), even when controlling for age and negative symptoms (Standard Beta: -0.36; CI= -2.52 a -13.71).

DISCUSSION

The association between greater lipid peroxidation, as assessed by TBARS, and worse performance in working memory corroborates theoretical models of greater vulnerability of schizophrenia to oxidative stress.

Characterization of Aspergillus fumigatus Extracellular Vesicles and Their Effects on Macrophages and Neutrophils Functions

Extracellular vesicles (EVs) has been considered an alternative process for intercellular communication. EVs release by filamentous fungi and the role of vesicular secretion during fungus-host cells interaction remain unknown. Here, we identified the secretion of EVs from the pathogenic filamentous fungus, Aspergillus fumigatus. Analysis of the structure of EVs demonstrated that A. fumigatus produces round shaped bilayer structures ranging from 100 to 200 nm size, containing ergosterol and a myriad of proteins involved in REDOX, cell wall remodeling and metabolic functions of the fungus. We demonstrated that macrophages can phagocytose A. fumigatus EVs. Phagocytic cells, stimulated with EVs, increased fungal clearance after A. fumigatus conidia challenge. EVs were also able to induce the production of TNF-α and CCL2 by macrophages and a synergistic effect was observed in the production of these mediators when the cells were challenged with the conidia. In bone marrow-derived neutrophils (BMDN) treated with EVs, there was enhancement of the production of TNF-α and IL-1β in response to conidia. Together, our results demonstrate, for the first time, that A. fumigatus produces EVs containing a diverse set of proteins involved in fungal physiology and virulence. Moreover, EVs are biologically active and stimulate production of inflammatory mediators and fungal clearance.

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.

Eosinophil-Associated Innate IL-17 Response Promotes Aspergillus fumigatus Lung Pathology

Aspergillus fumigatus is a common widespread microorganism with environmental, biological and clinical relevance. After inhalation, swollen conidia can germinate, colonize and invade pulmonary tissues. Eosinophils have been described as key cells in A. fumigatus lung infection. However, their specific role in protecting or damaging lung tissue as well as their relatioship among different A. fumigatus strains is poorly understood. Previously, it has been reported that eosinophils are able to produce IL-17 and mediate an innate response that protected mice from infection using Af293 and CEA10 strains. Here, we have developed a set of new experiments with the CEA17-derived A1163 strain of A. fumigatus. Using ΔdblGATA1 mice, we demonstrate that eosinophils produce IL-17 and are involved in control of neutrophil, macrophage and lymphocyte recruitment. We found that eosinophils also induce high levels of cytokines and chemokines, generating an intense inflammatory process. Eosinophils are responsible for increased pulmonary dysfunction and elevated lethality rates in mice. Curiously, fungal burden was not affected. To address the role of IL-17 signaling, pharmacological inhibition of this mediator in the airways with anti-IL-17 antibody was able to reduce inflammation in the airways and protect infected mice. In conclusion, our results demonstrate that eosinophils control IL-17-mediated response and contribute to lung pathology after A. fumigatus infection. Therefore, eosinophils may represent a potential target for controlling exacerbated inflammation and prevent tissue damage during this fungal infection.

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.

Cryptococcus gattii: in vitro susceptibility to photodynamic inactivation

Cryptococus gattii is an emergent primary human pathogen that causes meningismus, papilledema, high intracranial pressure and focal involvement of the central nervous system in immunocompetent hosts. Prolonged antifungal therapy is the conventional treatment, but it is highly toxic, selects for resistant strains, contributes to therapy failure and has a poor prognosis. Photodynamic inactivation (PDI) offers a promising possibility for the alternative treatment of cryptococcosis. The aim of this study was to test the effectiveness of toluidine blue O (TBO) and light-emitting diode (LED) against C. gattii strains with distinct susceptibility profile to antifungal drugs (amphotericin B: 0.015-1.0 μg mL(-1); itraconazole: 0.015-2 μg mL(-1); fluconazole: 4-64 μg mL(-1)). Using 25 μM (6.76 μg mL(-1)) TBO and LED energy density of 54 J cm(-2) these fungal isolates presented variable susceptibility to PDI. The production of reactive oxygen species (ROS)/peroxynitrite was determined, and the catalase and peroxidase activities were measured. After PDI, high amounts of ROS/peroxynitrite are produced and higher catalase and peroxidase activities could be correlated with a lower susceptibility of C. gattii isolates to PDI. These results indicate that PDI could be an alternative to C. gattii growth inhibition, even of isolates less susceptible to classical antifungal drugs, also pointing to mechanisms related to their variable susceptibility behavior.

Involvement of the chemokine RANTES (CCL5) in resistance to experimental infection with Leishmania major

The expression and putative role of chemokines during infection with Leishmania major in mice were investigated. CCL5 expression correlates with resistance, and blockade of CCL5 rendered mice more susceptible to infection. CCL5 is part of the cascade of events leading to efficient parasite control in L. major infection.