Biology subjects

Aufiero, M.

Publications and source records attributed to Aufiero, M..

4 recordsLinked to original sources

bioRxiv2025

Antibiotic-induced microbiota disruption impairs neutrophil-mediated immunity to Aspergillus fumigatus

Aspergillus fumigatus is an environmental mold that forms ubiquitous airborne conidia and can cause life-threatening infections in immunocompromised individuals. Invasive aspergillosis occurs in patients with quantitative or qualitative neutrophil defects, who often receive systemic antibiotics to prevent or manage bacterial infections. Antibiotic-induced bacterial dysbiosis has been linked to impaired neutrophil bactericidal activity and to intestinal commensal bacteria escape during systemic candidiasis, though it remains unclear whether receipt of antibacterial antibiotics impairs neutrophil-dependent defenses against inhaled mold pathogens in the lung. Herein, we measured the outcome of Aspergillus challenge in C57BL/6J mice that were treated with different antibiotics in the drinking water for three weeks prior to experimental infection. We found that ampicillin but not neomycin or vancomycin treatment significantly increased murine mortality and lung fungal burden. The heightened susceptibility was associated with impaired fungal killing by lung-infiltrating neutrophils and monocytes, as well as reduced neutrophil production of NADPH oxidase 2 (NOX2)-dependent reactive oxygen species (ROS). These findings demonstrate that systemic antibiotic treatment can compromise pulmonary anti-Aspergillus immunity and suggest that the host microbiota can enhance neutrophil fungicidal activity by promoting NOX2-mediated ROS production. IMPORTANCEAspergillus fumigatus is an environmental mold that causes invasive pulmonary disease in immunocompromised individuals. Owing to limited diagnostic tools, a narrow arsenal of effective treatments, and rising antifungal resistance, the World Health Organization (WHO) has designated Aspergillus as a critical priority fungal pathogen, highlighting the urgent need for further research. Patients with compromised immunity often receive broad-spectrum antibiotics to prevent or treat opportunistic infections, leading to significant disruption of the resident commensal microbiota. This antibiotic-induced dysbiosis has been linked to Clostridium difficile colitis and to intestinal overgrowth of vancomycin-resistant Enterococcus and Candida parapsilosis, preceding bloodstream infection. However, the impact of antibiotic treatment on susceptibility to invasive pulmonary aspergillosis remains undefined. In this study, we found that oral treatment with ampicillin, but not neomycin or vancomycin, significantly increased mortality in mice following Aspergillus infection. Neutrophils from the lungs of ampicillin-treated mice also showed markedly impaired fungal killing. These findings raise the possibility that preserving microbiome integrity during antibiotic treatment could enhance immune protection against invasive aspergillosis in at-risk patient groups.

immunology↗

bioRxiv2024

Perforin-2 is dispensable for host defense against Aspergillus fumigatus and Candida albicans

Myeloid phagocytes are essential for antifungal immunity against pulmonary Aspergillus fumigatus and systemic Candida albicans infections. However, the molecular mechanisms underlying fungal clearance by phagocytes remain incompletely understood. In this study, we investigated the role of perforin-2 (Mpeg1) in antifungal immunity. We found that Mpeg1-/- mice generated on a mixed C57BL/6J-DBA/2 background exhibited enhanced survival, reduced lung fungal burden, and greater neutrophil fungal killing activity compared to wild-type C57BL/6J (B6) mice, suggesting that perforin-2 may impair antifungal immune responses. However, when we compared Mpeg1-/- mice with co-housed Mpeg+/+ littermate controls, these differences were no longer observed, indicating that initial findings were likely influenced by differences in the murine genetic background or the microbiota composition. Furthermore, perforin-2 was dispensable for antifungal immunity during C. albicans bloodstream infection. These results suggest that perforin-2 is not essential for host defense against fungal infections in otherwise immune competent mice and highlight the importance of generating co-housed littermate controls to minimize murine genetic and microbiota-related factors in studies of host defense mechanisms. IMPORTANCEAspergillus fumigatus is the leading cause of invasive aspergillosis (IA), which is associated with significant mortality, particularly in immunocompromised patients such as those with acute leukemia or undergoing hematopoietic stem cell transplants, where death rates reach 40-50% despite standard care. Treatments for IA remain limited and resistance to antifungals is emerging, leading the World Health Organization to recently classify A. fumigatus as a critical priority fungal pathogen. A greater understanding of how the immune system clears A. fumigatus could lead to host-directed therapies that could complement our current armamentarium of antifungal drugs and improve patient outcomes. Our findings reveal that perforin-2 is not essential for antifungal immunity against A. fumigatus in otherwise immune-competent mice and underscore the necessity of using co-housed littermate controls to avoid confounding factors in immunological studies.

immunology↗

bioRxiv2023

Dectin-1/CARD9-induction of the TFEB and TFE3 gene network is dispensable for phagocyte anti-Aspergillus activity in the lung

Myeloid phagocytes of the respiratory immune system, such as neutrophils, monocytes, and alveolar macrophages, are essential for immunity to Aspergillus fumigatus, the most common etiologic agent of mold pneumonia worldwide. Following engulfment of A. fumigatus conidia, fusion of the phagosome with the lysosome, is a critical process for killing conidia. TFEB and TFE3 are transcription factors that regulate lysosomal biogenesis under stress and are activated by inflammatory stimuli in macrophages, but it is unknown whether TFEB and TFE3 contribute to anti-Aspergillus immunity during infection. We found that lung neutrophils express TFEB and TFE3, and their target genes were upregulated during A. fumigatus lung infection. Additionally, A. fumigatus infection induced nuclear accumulation of TFEB and TFE3 in macrophages in a process regulated by Dectin-1 and CARD9 signaling. Genetic deletion of Tfeb and Tfe3 impaired macrophage killing of A. fumigatus conidia. However, in a murine immune competent Aspergillus infection model with genetic deficiency of Tfeb and Tfe3 in hematopoietic cells, we surprisingly found that lung myeloid phagocytes had no defects in conidial phagocytosis or killing. Loss of TFEB and TFE3 did not impact murine survival or clearance of A. fumigatus from the lungs. Our findings indicate that myeloid phagocytes activate TFEB and TFE3 in response to A. fumigatus, and while this pathway promotes macrophage fungicidal activity in vitro, genetic loss can be functionally compensated at the portal of infection in the lung, resulting in no measurable defect in fungal control and host survival.

immunology↗

bioRxiv2023

Aspergillus fumigatus cytochrome c impacts conidial survival during sterilizing immunity

Invasive pulmonary aspergillosis (IPA) is a life-threatening infection caused by species in the ubiquitous fungal genus Aspergillus. While leukocyte-generated reactive oxygen species (ROS) are critical for the clearance of fungal conidia from the lung and resistance to IPA, the processes that govern ROS-dependent fungal cell death remain poorly defined. Using a flow cytometric approach that monitors two independent cell death markers, an endogenous histone H2A:mRFP nuclear integrity reporter and Sytox Blue cell impermeable (live/dead) stain, we observed that loss of A. fumigatus cytochrome c (cycA) results in reduced susceptibility to cell death from hydrogen peroxide (H2O2) treatment. Consistent with these observations in vitro, loss of cycA confers resistance to both NADPH-oxidase -dependent and -independent killing by host leukocytes. Fungal ROS resistance is partly mediated in part by Bir1, a homolog to survivin in humans, as Bir1 overexpression results in decreased ROS-induced conidial cell death and reduced killing by innate immune cells in vivo. We further report that overexpression of the Bir1 N-terminal BIR domain in A. fumigatus conidia results in altered expression of metabolic genes that functionally converge on mitochondrial function and cytochrome c (cycA) activity. Together, these studies demonstrate that cycA in A. fumigatus contributes to cell death responses that are induced by exogenous H2O2 and by host leukocytes. ImportanceAspergillus fumigatus can cause a life-threatening infection known as invasive pulmonary aspergillosis (IPA), which is marked by fungus-attributable mortality rates of 20%-30%. Individuals at risk of IPA harbor genetic mutations or incur pharmacologic defects that impair myeloid cell numbers and/or function, exemplified by bone marrow transplant recipients, patients that receive corticosteroid therapy, or patients with Chronic Granulomatous Disease (CGD). However, treatments for Aspergillus infections remains limited, and resistance to the few existing drug classes is emerging. Recently, the World Health Organization (WHO) classified A. fumigatus as a critical priority fungal pathogen. Our research identifies an important aspect of fungal biology that impacts susceptibility to leukocyte killing. Furthering our understanding of mechanisms that mediate the outcome of fungal-leukocyte interactions will increase our understanding of both the underlying fungal biology governing cell death and innate immune evasion strategies utilized during mammalian infection pathogenesis. Consequently, our studies are a critical step toward leveraging these mechanisms for novel therapeutic advances.

microbiology↗