Biology subjects

Pinzan, C. F.

Publications and source records attributed to Pinzan, C. F..

10 recordsLinked to original sources

bioRxiv2026

Opportunistic pathogenicity in fungi can transcend species boundaries

Multiple fungal lineages have independently evolved the ability to opportunistically infect humans, imposing a major burden on public health. Opportunistic pathogenicity requires the confluence of pre-existing fungal traits that facilitate host colonization (e.g., the ability to grow at 37{degrees}C) and host immune filters that permit the survival of some colonizers (e.g., inborn errors of immunity). Numerous studies have shown that fungal pathogens can exhibit extensive strain-to-strain variation in the ability to cause disease. Moreover, it is also well established that non-pathogenic fungi can occasionally cause severe infections. Together, these observations raise the question: What differentiates opportunistic fungal pathogens from non-pathogens? To address this empirically, we compared phenotypic, metabolomic, and genomic variation between Aspergillus fumigatus, an organism responsible for more than 300,000 infections per year, and Aspergillus fischeri, a close relative that is not considered clinically relevant. By examining 26 phenotypic traits across 16 representative strains of A. fumigatus and 16 of A. fischeri, we found that infection-relevant traits measured under in vitro monoculture conditions showed species-specific distributions, whereas traits measured under in vitro coculture with murine macrophages overlapped. Strikingly, strains of the two species also overlapped in their virulence profiles in an immunocompromised murine model of pulmonary aspergillosis; three strains of A. fischeri exhibited lethality rates of >50% while two A. fumigatus strains were among the least virulent of all 32 strains tested. Consistent with this overlap, we could not associate virulence variation with the presence of specific genomic elements, phenotypic traits, or secondary metabolites. Our results raise the hypothesis that opportunistic pathogenicity can extend beyond the boundaries of individual species. We propose a conceptual model in which the opportunistic pathogenic potential of any fungal strain is the product of complex interactions among numerous genomic, ecological, and host immunity factors.

evolutionary biology↗

bioRxiv2025

RAB5c controls the assembly of non-canonical autophagy machinery to promote phagosome maturation and microbicidal function of macrophages

Non-canonical conjugation of ATG8 proteins, including LC3, to single membranes implicates the autophagy machinery in cell functions unrelated to metabolic stress. One such pathway is LC3-associated phagocytosis (LAP), which aids in phagosome maturation and subsequent signaling upon cargo uptake mediated by certain innate immunity-associated receptors. Here, we show that a specific isoform of RAB5 GTPases, the molecular switches controlling early endosome traffic, is necessary for LAP. We demonstrate that RAB5c regulates phagosome recruitment and function of complexes required for phosphatidylinositol-3-phosphate [PI(3)P] and reactive oxygen species (ROS) generation by macrophages. RAB5c facilitates phagosome translocation of the V-ATPase transmembrane core, which is needed for ATG16L1 binding and consequent LC3 conjugation. RAB5c depletion impaired macrophage elimination of the fungal pathogen Aspergillus fumigatus and disruption of the V-ATPase-ATG16L1 axis increased susceptibility in vivo. Therefore, early endosome-to-phagosome traffic is differentially regulated to promote LAP and ROS contributes to resistance against A. fumigatus by effecting LAP. HIGHLIGHTSO_LIRAB5c is required for LC3-associated phagocytosis C_LIO_LIRAB5c finetunes NAPDH oxidase assembly and ROS generation in the phagosome C_LIO_LIRAB5c regulates V-ATPase assembly on the phagosome C_LIO_LIRAB5c and V-ATPase-ATG16L1 axis are required for the killing of A. fumigatus C_LI

immunology↗

bioRxiv2024

Brilacidin, a novel antifungal agent against Cryptococcus neoformans

Cryptococcus neoformans causes cryptococcosis, one of the most prevalent fungal diseases, generally characterized by meningitis. There is a limited and not very effective number of drugs available to combat this disease. In this manuscript, we show the host defense peptide mimetic brilacidin (BRI) as a promising antifungal drug against C. neoformans. BRI is able to affect the organization of the cell membrane, increasing fungal cell permeability. We also investigated the effects of BRI against the model system Saccharomyces cerevisiae by analyzing libraries of mutants grown in the presence of BRI. In S. cerevisiae, BRI also affects the cell membrane organization, but in addition the cell wall integrity pathway and calcium metabolism. In vivo experiments show BRI significantly reduces C. neoformans survival inside macrophages and partially clears C. neoformans lung infection in an immunocompetent murine model of invasive pulmonary cryptococcosis. We also observed that BRI interacts with caspofungin (CAS) and amphotericin (AmB), potentiating their mechanism of action against C. neoformans. BRI+CAS affects endocytic movement, calcineurin, and mitogen activated protein kinases. Our results indicate that BRI is a novel antifungal drug against cryptococcosis. ImportanceInvasive fungal infections have a high mortality rate causing more deaths annually than tuberculosis or malaria. Cryptococcosis, one of the most prevalent fungal diseases, is generally characterized by meningitis and is mainly caused by two closely related species of basidiomycetous yeasts, Cryptococcus neoformans and Cryptococcus gattii. There are few therapeutic options for treating cryptococcosis and searching for new antifungal agents against this disease is very important. Here, we present brilacidin (BRI) as a potential antifungal agent against C. neoformans. BRI is a small molecule host defense peptide mimetic that has previously exhibited broad-spectrum immunomodulatory/anti-inflammatory activity against bacteria and viruses. BRI alone was shown to inhibit the growth of C. neoformans, acting as a fungicidal drug, but surprisingly also potentiated the activity of caspofungin (CAS) against this species. We investigated the mechanism of action of BRI and BRI+CAS against C. neoformans. We propose BRI as a new antifungal agent against cryptococcosis.

microbiology↗

bioRxiv2024

Brilacidin, a host defense peptide mimetic, potentiates ibrexafungerp antifungal activity against the human pathogenic fungus Aspergillus fumigatus

Aspergillus fumigatus is the primary etiological agent of aspergillosis. Here, we show that the host defense peptide mimetic, brilacidin (BRI) can potentiate ibrexafungerp (IBX) against clinical isolates of A. fumigatus. CAS-resistant strains with mutations in fks1 that encodes the 1,3-{beta}-D-glucan synthase are not IBX-resistant and BRI+IBX can inhibit their growth. The combination of BRI+IBX plays a fungicidal role, increases the fungal cell permeability and decreases the fungal survival in the presence of A549 epithelial cells.

microbiology↗

bioRxiv2024

Strain heterogeneity in a non-pathogenic fungus highlights factors contributing to virulence

Fungal pathogens exhibit extensive strain heterogeneity, including variation in virulence. Whether closely related non-pathogenic species also exhibit strain heterogeneity remains unknown. Here, we comprehensively characterized the pathogenic potentials (i.e., the ability to cause morbidity and mortality) of 16 diverse strains of Aspergillus fischeri, a non-pathogenic close relative of the major pathogen Aspergillus fumigatus. In vitro immune response assays and in vivo virulence assays using a mouse model of pulmonary aspergillosis showed that A. fischeri strains varied widely in their pathogenic potential. Furthermore, pangenome analyses suggest that A. fischeri genomic and phenotypic diversity is even greater. Genomic, transcriptomic, and metabolomic profiling identified several pathways and secondary metabolites associated with variation in virulence. Notably, strain virulence was associated with the simultaneous presence of the secondary metabolites hexadehydroastechrome and gliotoxin. We submit that examining the pathogenic potentials of non-pathogenic close relatives is key for understanding the origins of fungal pathogenicity.

evolutionary biology↗

bioRxiv2024

Milteforan, a promising veterinary commercial product against feline sporotrichosis

Sporotrichosis, the cutaneous mycosis most commonly reported in Latin America, is caused by the Sporothrix clinical clade species, including Sporothrix brasiliensis and Sporothrix schenckii sensu stricto. In Brazil, S. brasiliensis represents a vital health threat to humans and domestic animals due to its zoonotic transmission. Itraconazole, terbinafine, and amphotericin B are the most used antifungals for treating sporotrichosis. However, many strains of S. brasiliensis and S. schenckii have shown resistance to these agents, highlighting the importance of finding new therapeutic options. Here, we demonstrate that milteforan, a commercial veterinary product against dog leishmaniasis whose active principle is miltefosine, is a possible therapeutic alternative for the treatment of sporotrichosis, as observed by its fungicidal activity in vitro against different strains of S. brasiliensis and S. schenckii, and by its antifungal activity when used to treat infected epithelial cells and macrophages. Our results suggest milteforan as a possible alternative to treat feline sporotrichosis.

microbiology↗

bioRxiv2023

Deacetylation by sirtuins is important for Aspergillus fumigatus pathogenesis and virulence

Protein acetylation is a crucial post-translational modification that controls gene expression and a variety of biological processes. Sirtuins, a prominent class of NAD+-dependent lysine deacetylases, serve as key regulators of protein acetylation and gene expression in eukaryotes. In this study, six single knockout strains of fungal pathogen Aspergillus fumigatus were constructed, in addition to a strain lacking all predicted sirtuins (SIRTKO). Phenotypic assays suggest that sirtuins are involved in cell wall integrity, secondary metabolite production, thermotolerance, and virulence. AfsirE deletion resulted in attenuation of virulence, as demonstrated in murine and Galleria infection models. The absence of AfSirE leads to altered acetylation status of proteins, including histones and non-histones, resulting in significant changes in the expression of genes associated with secondary metabolism, cell wall biosynthesis, and virulence factors. These findings encourage testing sirtuin inhibitors as potential therapeutic strategies to combat A. fumigatus infections or in combination therapy with available antifungals.

microbiology↗

bioRxiv2023

A phylogenetic approach to explore the Aspergillus fumigatus conidial surface-associated proteome and its role in pathogenesis

Aspergillus fumigatus, an important pulmonary fungal pathogen causing several diseases collectively called aspergillosis, relies on asexual spores or conidia for initiating host infection. Here, we used a phylogenomic approach to compare proteins in the conidial surface of A. fumigatus, two closely related non-pathogenic species, Aspergillus fischeri and Aspergillus oerlinghausenensis, and the cryptic pathogen Aspergillus lentulus. After identifying 62 proteins uniquely expressed on the A. fumigatus conidial surface, we deleted 42 genes encoding conidial proteins. We found deletion of 33 of these genes altered susceptibility to macrophage killing, penetration and damage to epithelial cells, and cytokine production. Notably, a gene that encodes glycosylasparaginase, which modulates levels of the host pro-inflammatory cytokine IL-1{beta}, is important for infection in an immunocompetent murine model of fungal disease. These results suggest that A. fumigatus conidial surface proteins and effectors are important for evasion and modulation of the immune response at the onset of fungal infection.

microbiology↗

bioRxiv2022

A host defense peptide mimetic, brilacidin, potentiates caspofungin antifungal activity against human pathogenic fungi

A. fumigatus is the main etiological agent of a group of heterogeneous diseases called aspergillosis of which the most lethal form is the invasive pulmonary aspergillosis (IPA). Fungicidal azoles and amphotericin B are the first line defense against A. fumigatus, but fungistatic echinocandins, such as caspofungin (CAS), can be used as salvage therapy for IPA. Here, we screened repurposing libraries and identified several compounds that potentiate CAS activity against A. fumigatus, including the host defense peptide mimetic, brilacidin (BRI). BRI converts CAS into a fungicidal drug and potentiates voriconazole (VOR) against A. fumigatus. BRI increases the ability of both CAS and VOR to control A. fumigatus biofilm growth. BRI depolarizes the A. fumigatus cell membrane leading to disruption of membrane potential. By using a combination of protein kinase inhibitors and screening of a catalytic subunit null mutant library, we identified the mitogen activated protein kinase (MAPK) MpkA and the phosphatase calcineurin as mediators of the synergistic action of BRI. These results suggest the most likely BRI mechanism of action for CAS potentiation is the inhibition of A. fumigatus cell wall integrity (CWI) pathway. BRI potentiates CAS activity against C. albicans, C. auris, and C. neoformans. Interestingly, BRI overcomes the CAS-acquired resistance in both A. fumigatus and C. albicans and the CAS-intrinsic resistance in C. neoformans. BRI also has an additive effect on the activity of posaconazole (POSA) against several Mucorales fungi. Cell toxicity assays and fungal burden studies in an immunosuppressed murine model of IPA showed that BRI combined with CAS is not toxic to the cells and significantly clears A. fumigatus lung infection, respectively. Our results indicate that combinations of BRI and antifungal drugs in clinical use are likely to improve the treatment outcome of IPA and other fungal infections.

microbiology↗

bioRxiv2017

Toxoplasma gondii microneme proteins 1 and 4 bind to Toll-like receptors 2 and 4 N-glycans triggering innate immune response

Infection of host cells by Toxoplasma gondii is an active process, which is regulated by secretion of microneme (MICs) and rhoptry proteins (ROPs and RONs) from specialized organelles in the apical pole of the parasite. MIC1, MIC4 and MIC6 assemble into an adhesin complex, secreted on the parasite surface and function to promote infection competency. MIC1 and MIC4 are known to bind terminal sialic acid residues and galactose residues, respectively and to induce IL-12 production from splenocytes. Here we show that rMIC1- and rMIC4-stimulated dendritic cells and macrophages to produce proinflammatory cytokines, and they do so by engaging TLR2 and TLR4. This process depends on sugar recognition, since point mutations in the carbohydrate-recognition domains (CRD) of rMIC1 and rMIC4 inhibit innate immune cells activation. HEK cells transfected with TLR2 glycomutants were selectively unresponsive to MICs. Following in vitro infection, parasites lacking MIC1 or MIC4, as well as expressing MIC proteins with point mutations in their CRD, failed to induce wild-type (WT) levels of IL-12 secretion by innate immune cells. However, only MIC1 was shown to impact systemic levels of IL-12 and IFN-{gamma} in vivo. Together, our data show that MIC1 and MIC4 interact physically with TLR2 and TLR4 N-glycans to trigger IL-12 responses, and MIC1 is playing a significant role in vivo by altering T. gondii infection competency and murine pathogenesis.\n\nAUTHOR SUMMARYToxoplasmosis is caused by the protozoan Toxoplasma gondii, belonging to the Apicomplexa phylum. This phylum comprises important parasites able to infect a broad diversity of animals, including humans. A particularity of T. gondii is its ability to invade virtually any nucleated cell of all warm-blooded animals through an active process, which depends on the secretion of adhesin proteins. These proteins are discharged by specialized organelles localized in the parasite apical region, and termed micronemes and rhoptries. We show in this study that two microneme proteins from T. gondii utilize their adhesion activity to stimulate innate immunity. These microneme proteins, denoted MIC1 and MIC4, recognize specific sugars on receptors expressed on the surface of mammalian immune cells. This binding activates these innate immune cells to secrete cytokines, which promotes efficient host defense mechanisms against the parasite and regulate their pathogenesis. This activity promotes a chronic infection by controlling parasite replication during acute infection.

immunology↗