title: Agents that activate the High Osmolarity Glycerol pathway as a means to combat pathogenic molds.
abstract: Treatment of invasive fungal infections often fails due to the limited number of therapeutic options. In this study, we have analyzed the impact of agents activating the High Osmolarity Glycerol (HOG) pathway on molds that cause infections in humans and livestock. We found that agents like fludioxonil and iprodione, have a clear anti-fungal activity against pathogenic Aspergillus, Lichtheimia, Rhizopus and Scedosporium species. Only A. terreus turned out to be resistant to fludioxonil, even though it is sensitive to iprodione and able to adapt to hyperosmotic conditions. Moreover, the A. terreus tcsC gene can fully complement an A. fumigatus ΔtcsC mutant, thereby also restoring its sensitivity to fludioxonil. The particular phenotype of A. terreus is therefore likely to be independent of its TcsC kinase. In a second part of this study, we further explored the impact of fludioxonil using A. fumigatus as a model organism. When applied in concentrations of 1-2μg/ml, fludioxonil causes an immediate growth arrest and, after longer exposure, a quantitative killing. Hyphae respond to fludioxonil by the formation of new septa and closure of nearly all septal pores. Mitosis occurs in all compartments and is accompanied by a re-localization of the NimA kinase to the cytoplasm. In the swollen compartments, the massive extension of the cell wall triggers a substantial reorganization resulting in an enhanced incorporation of chitin and, most strikingly, a massive loss of galactomannan. Hence, HOG-activating agents have dramatic cell biological consequences and may represent a valuable, future element in the armory that can be used to combat mold infections.
authors.affiliation: Institute for Infectious Diseases and Zoonoses, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Annegret
authors.initials: A
authors.lastname: Wiedemann
authors.affiliation: Institute for Infectious Diseases and Zoonoses, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Spadinger
authors.affiliation: Max-von-Pettenkofer-Institute, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Löwe
authors.affiliation: Max-von-Pettenkofer-Institute, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Allison
authors.initials: A
authors.lastname: Seeger
authors.affiliation: Institute for Infectious Diseases and Zoonoses, Ludwig-Maximilians-University, Munich, Germany; Max-von-Pettenkofer-Institute, Ludwig-Maximilians-University, Munich, Germany; German Center for Infection Research (DZIF), Munich, Germany. Electronic address: frank.ebel@lmu.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Ebel
mesh_terms: D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology*; D004149:Dioxoles / Q000494:pharmacology*; D005658:Fungi / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology*; D006827:Hydantoins / Q000494:pharmacology*; D050296:Microbial Viability / Q000187:drug effects*; D009997:Osmotic Pressure; D011758:Pyrroles / Q000494:pharmacology*
chemical_list: D000935:Antifungal Agents; D004149:Dioxoles; D006827:Hydantoins; D011758:Pyrroles; D000620:Aminoimidazole Carboxamide; C108339:fludioxonil; C033148:iprodione
keywords: Antifungals; Aspergillus fumigatus; Aspergillus terreus; Fludioxonil; HOG pathway; Hyperosmotic stress; Mucorales; Scedosporium; TcsC; Type III hybrid histidine kinase