title: Modulation of expression of superantigens by human transferrin and lactoferrin: a novel mechanism in host-Streptococcus interactions.
abstract: The role played by host-pathogen interactions in regulation of expression of streptococcal virulence factors in vivo is beginning to become clear. We have reported that the expression of 2 streptococcal virulence factors, the streptococcal pyrogenic exotoxin (Spe) A and the cysteine protease SpeB, was reciprocally modulated during infection with Streptococcus pyogenes. To identify host signals mediating this reciprocal regulation, we cocultured clonal M1T1 isolates with human peripheral blood mononuclear cells (PBMCs). In accordance with our in vivo findings, when bacteria were in direct contact with human PBMCs or were separated in transwells, expression of speA was induced, whereas expression of speB was down-regulated. This phenomenon was mediated by transferrin and lactoferrin and was influenced by the iron-saturation status of these proteins. Iron chelation from media induced expression of speA, but to a much lesser degree than did that with apotransferrin and lactoferrin, suggesting additional effects of these ferrins on modulation of expression of speA and speB. Thus, ferrins may play an important role in host-pathogen interactions in skin and mucosal tissues.
authors.affiliation: Veterans Affairs Medical Center, Research Service, and Department of Surgery, University of Tennessee Health Science Center, Memphis, Tennessee 38104, USA. rkansal@utmem.edu
authors.forename: Rita G
authors.initials: RG
authors.lastname: Kansal
authors.forename: Ramy K
authors.initials: RK
authors.lastname: Aziz
authors.forename: Malak
authors.initials: M
authors.lastname: Kotb
mesh_terms: D000942:Antigens, Bacterial / Q000096:biosynthesis; D001059:Apoproteins / Q000502:physiology*; D001426:Bacterial Proteins / Q000096:biosynthesis*; D015536:Down-Regulation; D005098:Exotoxins / Q000096:biosynthesis*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007781:Lactoferrin / Q000502:physiology*; D007963:Leukocytes, Mononuclear / Q000502:physiology; D008565:Membrane Proteins / Q000096:biosynthesis*; D013297:Streptococcus pyogenes / Q000276:immunology*; D018089:Superantigens / Q000096:biosynthesis*; D014168:Transferrin / Q000502:physiology*; D015854:Up-Regulation
chemical_list: D000942:Antigens, Bacterial; D001059:Apoproteins; D001426:Bacterial Proteins; D005098:Exotoxins; D008565:Membrane Proteins; C117980:SpeA protein, Streptococcus pyogenes; D018089:Superantigens; D014168:Transferrin; C028284:apotransferrin; C027951:erythrogenic toxin; D007781:Lactoferrin