Project description:The study consists of the pathogens Lichtheimia corymbifera, Lichtheimia ramosa and non-pathogen Lichtheimia hyalospora untreated (control, CTRL) and during HSP90 inhibition (Geldanamycin, GDA), endoplasmic reticulum stress (Dithiothreitol, DTT), thermal stress (42°C, HEAT) and heat stress upon a concentration of 0.5 M NaCl (L. hyalospora only)
Project description:Fungi harbor unique primary and secondary metabolic pathways that represent a hidden treasure of biochemical and natural compounds. Their metabolism is central to their ability to interact with, to adapt to and to survive in host environments, and also to cause human disease and great harm. Among those, Lichtheimia corymbifera whose emergence as causative agent of mucormycosis prompted (i) its classification to the high priority fungal pathogens by the World Health Organization and (ii) its increasing importance as model organism for the study of invasive fungal infections. We reconstructed a genome-scale L. corymbifera metabolic model and show substantial differential metabolic activity down to pathway and reaction level to process carbohydrate or amino acid carbon sources. We furthermore adapt the model to proteome changes depending on human leukocyte presence and show fungal sphingolipid metabolic activity changes next to changes in cytoskeleton and tight junction associated leukocyte activity over three days of cultivation. These insights underline the possibility that L. corymbifera can potentially scavenge host-derived lipids to fortify its own cell membrane. We demonstrate that in silico metabolic predictions can provide testable hypotheses and can lead to the identification of metabolic processes which are essential for the development of targeted antifungal drugs and novel solutions for balancing host challenges.
Project description:Mucormycosis is a life-threatening disease especially in immunocompromised patients that was caused my mucoralean fungi. The rate of mortality is tremendously increased in the last decades due to the lack of appropriate diagnostic tools, insufficient knowledge about the immune response toward the mucormycosis and unavailability of specific antifungal drugs. Several species of mucoralean fungi cause mucormycosis such as Lichtheimia, Rhizopus, and Mucor. Lichtheimia species ranks the second and third cause of mucormycosis in Europe and the USA, respectively. In this study, we investigated the receptors present on the surface of immune cells that bind to the spores of Lichtheimia. We focus on two strains of L. corymbifera (FSU:9682 and FSU:10164) using resting and heat-killed spores. Additionally, we choose alveolar macrophages (MH-S) to carry out our experiment. MH-S is the first line of defense in the lung and the major component in the innate immune system. MH-S surface proteins were biotinylated and incubated with Lichtheimia spores. The surface proteins and putative binding partners were enriched by streptavidin. LC-MS/MS analysis showed that several proteins are highly expressed in presence of Lichtheimia spores, of which the heat shock protein family A (HSPA8) was one of the most abundant proteins. FACS analysis and immunofluorescence examination confirmed that HSPA8 is highly abundant on the surface of the MH-S, but not on the surface of Lichtheimia spores. Moreover, our study showed that the intensity of HSPA8 on the surface of MH-S depends on the multiplicity of infection (MOI). Additionally, the blocking with anti-HSPA8 antibody reduced the capability of MH-S to engulf the Lichtheimia spores, but not Aspergillus fumigatus spores. This confirms that HSPA8 is specific to Lichtheimia. THis is the first study addressing the determination of surface receptors of alveolar macrophages that in the context of Mucoralean fungi.
