Search

Prior infections can provide protection or enhance susceptibility to a subsequent infection through microorganism's interaction or host immunomodulation. Staphylococcus aureus (SA) and Cryptococcus gattii (CG) cause lungs infection, but it is unclear how they interact in vivo. This study aimed to study the effects of the primary SA lung infection on secondary cryptococcosis caused by CG in a murine model. The mice's survival, fungal burden, behavior, immune cells, cytokines, and chemokines were quantified to evaluate murine cryptococcosis under the influence of a previous SA infection. Further, fungal-bacterial in vitro interaction was studied in a culture medium and a phagocytosis assay. The primary infection with SA protects animals from the subsequent CG infection by reducing lethality, improving behavior, and impairing the fungal proliferation within the host. This phenotype was associated with the proinflammatory antifungal host response elicited by the bacteria in the early stage of cryptococcosis. There was no direct inhibition of CG by SA, although the phagocytic activity of macrophages was reduced. Identifying mechanisms involved in this protection may lead to new approaches for preventing and treating cryptococcosis., Competing Interests: Declaration of competing interest All authors in this study have no conflicts of interest., (Copyright © 2023 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Cryptococcosis is an invasive mycosis caused by Cryptococcus spp. that affects the lungs and the central nervous system (CNS). Due to the severity of the disease, it may occur concomitantly with other pathogens, as a coinfection. Pseudomonas aeruginosa (Pa), an opportunistic pathogen, can also cause pneumonia. In this work, we studied the interaction of C. gattii (Cg) and Pa, both in vitro and in vivo . Pa reduced growth of Cg by the secretion of inhibitory molecules in vitro . Macrophages previously stimulated with Pa presented increased fungicidal activity. In vivo , previous Pa infection reduced morbidity and delayed the lethality due to cryptococcosis. This phenotype was correlated with the decreased fungal burden in the lungs and brain, showing a delay of Cg translocation to the CNS. Also, there was increased production of IL-1β, CXCL-1, and IL-10, together with the influx of iNOS-positive macrophages and neutrophils to the lungs. Altogether, Pa turned the lung into a hostile environment to the growth of a secondary pathogen, making it difficult for the fungus to translocate to the CNS. Further, iNOS inhibition reverted the Pa protective phenotype, suggesting its important role in the coinfection. Altogether, the primary Pa infection leads to balanced pro-inflammatory and anti-inflammatory responses during Cg infection. This response provided better control of cryptococcosis and was decisive for the mild evolution of the disease and prolonged survival of coinfected mice in a mechanism dependent on iNOS., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Peres-Emidio, Freitas, Costa, Gouveia-Eufrasio, Silva, Santos, Carmo, Brito, Arifa, Bastos, Ribeiro, Oliveira, Silva, Paixão, Saliba, Fagundes, Souza and Santos.)

The genomes of a large number of Cryptococcus neoformans isolates have been sequenced and analyzed in recent years. These genomes have been used to understand the global population structure of this opportunistic pathogen. However, only a small number of South American isolates have been considered in these studies, and the population structure of C. neoformans in this part of the world remains elusive. Here, we analyzed the genomic sequences of 53 Brazilian Cryptococcus isolates and deciphered the C. neoformans population structure in this country. Our data reveal an African-like structure that suggested repeated intercontinental transports from Africa to South America. We also identified a mutator phenotype in one VNBII Brazilian isolate, exemplifying how fast-evolving isolates can shape the Cryptococcus population structure. Finally, phenotypic analyses revealed wide diversity but not lineage specificity in the expression of classical virulence traits within the set of isolates., (© The Author(s) 2021. Published by Oxford University Press on behalf of Genetics Society of America.)

Cryptococcosis, an invasive fungal infection distributed worldwide that affects both domestic and wild animals, has incredible rates regarding treatment failure, leading to the necessity of the development of new therapies. In this way, we aimed to evaluate the probiotic (Saccharomyces boulardii, Lactobacillus paracasei ST-11, and Lactobacillus rhamnosus GG) and antimicrobial photodynamic alternative therapies against Cryptococcus gattii in a murine model. Although previous studies suggest that these therapies can be promising against cryptococcosis, our experimental conditions for both probiotic and antimicrobial photodynamic therapies (aPDT) were not able to improve the survival of mice with cryptococcosis, even with the treatment combined with fluconazole. Our results may help other researchers to find the best protocol to test alternative therapies against Cryptococcus gattii., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Influenza A virus (IAV) infects millions of people annually and predisposes to secondary bacterial infections. Inhalation of fungi within the Cryptococcus complex causes pulmonary disease with secondary meningo-encephalitis. Underlying pulmonary disease is a strong risk factor for development of C. gattii cryptococcosis though the effect of concurrent infection with IAV has not been studied. We developed an in vivo model of Influenza A H1N1 and C. gattii co-infection. Co-infection resulted in a major increase in morbidity and mortality, with severe lung damage and a high brain fungal burden when mice were infected in the acute phase of influenza multiplication. Furthermore, IAV alters the host response to C. gattii , leading to recruitment of significantly more neutrophils and macrophages into the lungs. Moreover, IAV induced the production of type 1 interferons (IFN-α4/β) and the levels of IFN-γ were significantly reduced, which can be associated with impairment of the immune response to Cryptococcus during co-infection. Phagocytosis, killing of cryptococci and production of reactive oxygen species (ROS) by IAV-infected macrophages were reduced, independent of previous IFN-γ stimulation, leading to increased proliferation of the fungus within macrophages. In conclusion, IAV infection is a predisposing factor for severe disease and adverse outcomes in mice co-infected with C. gattii .

Cryptococcus spp., the causative agents of cryptococcosis, are responsible for deaths of hundreds of thousands of people every year worldwide. The drawbacks of available therapeutic options are aggravated by the increased resistance of yeast to the drugs, resulting in inefficient therapy. Also, the antifungal 5FC is not available in many countries. Therefore, a combination of antifungal drugs may be an interesting option, but in vitro and theoretical data point to the possible antagonism between the main antifungals used to treat cryptococcosis, i.e., fluconazole (FLC), and amphotericin B (AMB). Therefore, in vivo studies are necessary to test the above hypothesis. In this study, the efficacy of FLC and AMB at controlling C. gattii infection was evaluated in a murine model of cryptococcosis caused by C. gattii. The infected mice were treated with FLC + AMB combinations and showed a significant improvement in survival as well as reduced morbidity, reduced lung fungal burden, and the absence of yeast in the brain when FLC was used at higher doses, according to the Tukey test and principal component analysis. Altogether, these results indicate that combinatorial optimization of antifungal therapy can be an option for effective control of cryptococcosis.

The inflammatory response plays a crucial role in infectious diseases, and the intestinal microbiota is linked to maturation of the immune system. However, the association between microbiota and the response against fungal infections has not been elucidated. Our aim was to evaluate the influence of microbiota on Cryptococcus gattii infection. Germ-free (GF), conventional (CV), conventionalized (CVN-mice that received feces from conventional animals), and LPS-stimulated mice were infected with C. gattii. GF mice were more susceptible to infection, showing lower survival, higher fungal burden in the lungs and brain, increased behavioral changes, reduced levels of IFN-γ, IL-1β and IL-17, and lower NFκBp65 phosphorylation compared to CV mice. Low expression of inflammatory cytokines was associated with smaller yeast cells and polysaccharide capsules (the main virulence factor of C. gattii) in the lungs, and less tissue damage. Furthermore, macrophages from GF mice showed reduced ability to engulf, produce ROS, and kill C. gattii. Restoration of microbiota (CVN mice) or LPS administration made GF mice more responsive to infection, which was associated with increased survival and higher levels of inflammatory mediators. This study is the first to demonstrate the influence of microbiota in the host response against C. gattii., (Copyright © 2016 Elsevier GmbH. All rights reserved.)