title: Effect of serine-type protease of Candida spp. isolated from linear gingival erythema of HIV-positive children: critical factors in the colonization.
abstract: BACKGROUND
  There are several kinds of oral soft tissue lesions that are common manifestations observed in human immunodeficiency virus (HIV)-infected children; for example, linear gingival erythema (LGE) that is a distinctive fiery red band along the margin of the gingivae. The etiology and pathogenesis of LGE are questionable, but a candidal origin has been suggested. Proteases are key virulence attributes produced by a variety of pathogenic fungi, including Candida. The objective of the present study is to identify the protease production in Candida species including, C. albicans (n=5), C. dubliniensis (n=1) and C. tropicalis (n=1), isolated directly from typical LGE lesions observed in six HIV-positive children, and also to test the effect of a serine protease inhibitor on the interaction of Candida spp. and epithelial cells in vitro.
  
  
  METHODS
  The ability of Candida strains to release proteases in the culture supernatant fluids was visualized by gelatin-SDS-PAGE. Gel strips containing 30-fold concentrated supernatant (1.5×10(8) yeasts) were incubated at 37°C for 48 h in 50 mM sodium phosphate buffer, pH 5.5. The concentrated supernatants were also incubated with fibronectin, laminin, immunoglobulin G, bovine serum albumin and human serum albumin. The effect of serine protease inhibitor on the interaction of Candida spp. and epithelial cells (MA 104) was measured after pre-treatment of fungi with the inhibitor (phenylmethylsulphonyl fluoride, PMSF).
  
  
  RESULTS
  All the extracellular proteases were completely inhibited by PMSF, identifying these activities as serine-type proteases. Interestingly, a common 62-kDa serine protease was observed in all Candida strains. The culture supernatants, rich in serine protease activities, cleaved several soluble proteinaceous substrates. Additionally, we demonstrated that pre-treatment of C. albicans, C. dubliniensis and C. tropicalis with PMSF diminished the interaction with epithelial cells.
  
  
  CONCLUSIONS
  Collectively, our results show that Candida spp. isolated from LGE lesions produced and secreted serine proteases and these enzymes may be involved in the initial colonization events.
authors.affiliation: Departamento de Odontopediatria e Ortodontia, Faculdade de Odontologia, Universidade Federal do Rio de Janeiro, Brazil. mbportela@hotmail.com
authors.forename: Maristela B
authors.initials: MB
authors.lastname: Portela
authors.forename: Ivete P R
authors.initials: IP
authors.lastname: Souza
authors.forename: Celina M
authors.initials: CM
authors.lastname: Abreu
authors.forename: Martinna
authors.initials: M
authors.lastname: Bertolini
authors.forename: Carla
authors.initials: C
authors.lastname: Holandino
authors.forename: Celuta S
authors.initials: CS
authors.lastname: Alviano
authors.forename: André L S
authors.initials: AL
authors.lastname: Santos
authors.forename: Rosangela M A
authors.initials: RM
authors.lastname: Soares
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000382:microbiology*; D002175:Candida / Q000145:classification / Q000201:enzymology* / Q000302:isolation & purification; D002180:Candidiasis, Oral / Q000150:complications* / Q000382:microbiology; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D018920:Coculture Techniques; D004847:Epithelial Cells / Q000166:cytology / Q000382:microbiology; D004890:Erythema / Q000209:etiology / Q000382:microbiology; D005260:Female; D005882:Gingival Diseases / Q000209:etiology / Q000382:microbiology*; D015658:HIV Infections / Q000150:complications* / Q000382:microbiology; D006679:HIV Seropositivity; D006801:Humans; D008297:Male; D010664:Phenylmethylsulfonyl Fluoride / Q000494:pharmacology; D057057:Serine Proteases / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology
chemical_list: D015842:Serine Proteinase Inhibitors; D010664:Phenylmethylsulfonyl Fluoride; D057057:Serine Proteases