title: Aspergillus terreus accessory conidia are multinucleated, hyperpolarizing structures that display differential dectin staining and can induce heightened inflammatory responses in a pulmonary model of aspergillosis.
abstract: In addition to phialidic conidia (PC), A. terreus produces accessory conidia (AC) both in vitro and in vivo. AC are distinct from PC in cell surface architecture, with the AC surfaces displaying more β-glucan, a molecule that can be a trigger for the induction of inflammatory responses. The present study follows β-glucan cell surface presentation throughout the course of germination of both types of conidia, and analyzes the differential capacity of AC and PC to elicit immune responses. Results show that AC display early, increased dectin-1 labeling on their cell surfaces compared to PC, and this differential dectin-1 labeling is sustained on the cell surface from the time of breaking dormancy through early germ tube emergence. Mouse alveolar macrophages showed a stronger inflammatory cytokine/chemokine response when challenged with AC than with PC in both ex vivo and in vivo experiments, correlating with the greater exposure of β-glucan exhibited by AC. Further, histopathologic staining of the lungs from mice challenged with AC demonstrated heightened cell recruitment and increased inflammatory response compared to the lungs of mice challenged with PC. Our study also demonstrates that AC are multinucleate structures with the ability to germinate rapidly, polarizing in multiple directions and producing several hyphal extensions. We present evidence that A. terreus AC are phenotypically distinct from PC and can be potent activators of the innate immune mechanism thus possibly playing a role in this organism's pathogenesis.
authors.affiliation: Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Eszter
authors.initials: E
authors.lastname: Deak
authors.forename: Michael
authors.initials: M
authors.lastname: Nelson
authors.forename: Yainitza
authors.initials: Y
authors.lastname: Hernández-Rodríguez
authors.forename: Lalitha
authors.initials: L
authors.lastname: Gade
authors.forename: John
authors.initials: J
authors.lastname: Baddley
authors.forename: Michelle
authors.initials: M
authors.lastname: Momany
authors.forename: Chad
authors.initials: C
authors.lastname: Steele
authors.forename: S Arunmozhi
authors.initials: SA
authors.lastname: Balajee
mesh_terms: D000818:Animals; D001230:Aspergillus / Q000737:chemistry / Q000166:cytology*; D002467:Cell Nucleus; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D006651:Histocytochemistry; D007249:Inflammation / Q000382:microbiology / Q000473:pathology*; D037181:Lectins, C-Type; D008168:Lung / Q000473:pathology; D016676:Macrophages, Alveolar / Q000276:immunology / Q000382:microbiology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008853:Microscopy; D009419:Nerve Tissue Proteins / Q000378:metabolism; D055732:Pulmonary Aspergillosis / Q000473:pathology*; D012376:Rodent Diseases / Q000382:microbiology / Q000473:pathology; D013172:Spores, Fungal / Q000737:chemistry / Q000166:cytology*; D013194:Staining and Labeling; D047071:beta-Glucans / Q000032:analysis*; D000099181:Dectin-1
chemical_list: D016207:Cytokines; D037181:Lectins, C-Type; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D047071:beta-Glucans; D000099181:Dectin-1