title: Impact of Candida albicans hyphal wall protein 1 (HWP1) genotype on biofilm production and fungal susceptibility to microglial cells.
abstract: The hyphal wall protein 1 (HWP1) gene of Candida albicans encodes for a fungal cell wall protein, required for hyphal development and yeast adhesion to epithelial cells; yet, its role in pathogenesis remains largely unknown. In the present study, we analyzed two C. albicans laboratory strains, the DAY286 (HWP1/HWP1) and the null mutant FJS24 (hwp1/hwp1) and six clinical isolates [3 harbouring the homozygous HWP1 gene (HWP1/HWP1) and 3 the heterologous gene (HWP1/hwp1)]. Biofilm production, fungal HWP1 mRNA levels and ultrastructural morphology were investigated; also, the susceptibility of these strains to microglial cells was evaluated, in terms of fungal damage and immune cell-mediated secretory response. When comparing the two laboratory strains, biofilm was produced to a similar extent independently on the genetic background, while the susceptibility to microglial cell-mediated damage was higher in the hwp1/hwp1 mutant than in the HWP1/HWP1 counterpart. Also, transmission electron microscopy revealed differences between the two in terms of abundance in surface adhesin-like structures, fungal cell wall shape and intracellular granules. When comparing the clinical isolates grouped according to their HWP1 genotype, reduced biofilm production and increased susceptibility to microglial cell-mediated damage occurred in the HWP1/hwp1 isolates with respect to the HWP1/HWP1 counterparts; furthermore, upon exposure to microglial cells, the HWP1/HWP1 isolates, but not the HWP1/hwp1 counterpart, showed enhanced HWP1 mRNA levels. Finally, both laboratory and clinical isolates exhibited reduced ability to stimulate TNFα and nitric oxide production by microglial cells in the case of heterozygous or null mutant HWP1 genotype. Overall, these data indicate that C. albicans HWP1 genotype influences pathogen morphological structure as well as its interaction with microglial cells, while fungal biofilm production results unaffected, thus arguing on its role as virulence factor that directly affects host mediated defences.
authors.affiliation: Department of Health Sciences, University of Milan, Polo Universitario San Paolo, Via Di Rudinì 8 - Blocco C, 8° piano, 20142 Milano, Italy; Department of Diagnostics, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Via del Pozzo 71, 41124 Modena, Italy.
authors.forename: Carlotta F
authors.initials: CF
authors.lastname: Orsi
authors.affiliation: Department of Health Sciences, University of Milan, Polo Universitario San Paolo, Via Di Rudinì 8 - Blocco C, 8° piano, 20142 Milano, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Borghi
authors.affiliation: Department of Diagnostics, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Via del Pozzo 71, 41124 Modena, Italy.
authors.forename: Bruna
authors.initials: B
authors.lastname: Colombari
authors.affiliation: Department of Diagnostics, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Via del Pozzo 71, 41124 Modena, Italy.
authors.forename: Rachele G
authors.initials: RG
authors.lastname: Neglia
authors.affiliation: Department of Life Sciences, University of Modena and Reggio Emilia, Via Campi 287, 41125 Modena, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Quaglino
authors.affiliation: Department of Diagnostics, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Via del Pozzo 71, 41124 Modena, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ardizzoni
authors.affiliation: Department of Health Sciences, University of Milan, Polo Universitario San Paolo, Via Di Rudinì 8 - Blocco C, 8° piano, 20142 Milano, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Morace
authors.affiliation: Department of Diagnostics, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Via del Pozzo 71, 41124 Modena, Italy. Electronic address: elisabetta.blasi@unimore.it.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Blasi
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D002176:Candida albicans / Q000166:cytology / Q000235:genetics / Q000276:immunology* / Q000502:physiology*; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics*; D020869:Gene Expression Profiling; D005838:Genotype; D025301:Hyphae / Q000254:growth & development; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics*; D050296:Microbial Viability; D017628:Microglia / Q000276:immunology* / Q000382:microbiology*; D046529:Microscopy, Electron, Transmission; D009569:Nitric Oxide / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; C118102:HWP1 protein, Candida albicans; D008562:Membrane Glycoproteins; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide
keywords: Biofilm; Candida albicans; Hyphal wall protein 1 (HWP1) genotype; Microglial cells