title: Involvement of peptidorhamnomannan in the interaction of Pseudallescheria boydii and HEp2 cells.
abstract: Pseudallescheria boydii is an emerging fungal pathogen that has a worldwide distribution. Virulence mechanisms of P. boydii are largely unknown. We studied the interaction between P. boydii and HEp2 cells and demonstrated that conidia of P. boydii attached to, and were ingested by, HEp2 cells in a time-dependent process. After 2 h of interaction, the conidia produced a germ-tube like projection, which was able to penetrate the epithelial cell membrane. Recently, our group characterized a peptidorhamnomannan (PRM) antigen on the cell surface of P. boydii. In order to better understand the role played by this surface glycoconjugate during cell adhesion and endocytosis, inhibition assays were performed using intact PRM and anti-PRM polyclonal antibody. When HEp2 cells were pre-treated with whole PRM molecule, the adhesion and endocytic indices were, respectively, 50% and 60% lower than in non-treated epithelial cells. Moreover, when the conidial cells were pre-incubated with anti-PRM antibodies, the adherence and endocytosis processes were inhibited in a dose-dependent manner. As PRM influenced the conidia P. boydii-HEp2 cell interaction, we also performed inhibition assays in order to observe which PRM moieties could be involved in this process. Treatment of PRM with proteinase K promoted a slight inhibition of adhesion. However, the de-O-glycosylated PRM molecule as well as the monosaccharide mannose was able to efficiently inhibit the adhesion and endocytic processes. In addition, our results indicate for the first time that P. boydii PRM binds to a polypeptide of 25 kDa on the HEp2 cell surface.
authors.affiliation: Departamento de Microbiologia Geral, Instituto de Microbiologia Professor Paulo de Góes, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Bloco I, Ilha do Fundão, Rio de Janeiro 21941-590, Brazil.
authors.forename: Marcia R
authors.initials: MR
authors.lastname: Pinto
authors.forename: Antônio C M
authors.initials: AC
authors.lastname: de Sá
authors.forename: Cristiana L
authors.initials: CL
authors.lastname: Limongi
authors.forename: Sonia
authors.initials: S
authors.lastname: Rozental
authors.forename: André L S
authors.initials: AL
authors.lastname: Santos
authors.forename: Eliana
authors.initials: E
authors.lastname: Barreto-Bergter
mesh_terms: D000946:Antigens, Fungal / Q000378:metabolism / Q000502:physiology; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D004705:Endocytosis; D019286:Endopeptidase K / Q000378:metabolism; D004847:Epithelial Cells / Q000382:microbiology*; D005656:Fungal Proteins / Q000378:metabolism / Q000502:physiology; D006023:Glycoproteins / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D008358:Mannose / Q000494:pharmacology; D008565:Membrane Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D008970:Molecular Weight; D011485:Protein Binding; D011541:Pseudallescheria / Q000254:growth & development / Q000472:pathogenicity*; D037521:Virulence Factors / Q000378:metabolism / Q000502:physiology
chemical_list: D000946:Antigens, Fungal; D005656:Fungal Proteins; D006023:Glycoproteins; D008565:Membrane Proteins; D037521:Virulence Factors; C107788:peptido-rhamnomannan; D019286:Endopeptidase K; D008358:Mannose