lactoferrin and Trichomonas-Vaginitis

Host defense responses of the human female genital tract mucosa to pathogenic microbes and viruses are mediated in part by the release of antimicrobial substances into the overlying mucosal fluid. While host defense has long been considered a prominent function of vaginal and cervical mucosae, evidence that cationic antimicrobial peptides and proteins have fundamental roles in the innate host defense of this tissue has only recently become available. This chapter explores elements of the physical and chemical defense barriers of the cervicovaginal mucosa, which protect against infections of the lower genital tract. Cationic antimicrobial and antiviral polypeptide components of cervicovaginal fluid are discussed in detail, with special emphasis placed on the defensin family of peptides as well as polypeptides that are active against viruses such as HIV-1. The reader should be cognizant that each polypeptide by itself does not provide complete protection of the genital tract. On the contrary, the abundance and multiplicity of antimicrobial peptides and proteins suggest protection of the cervicovaginal mucosa may be best realized from the aggregate effector molecules.

Topics: Acquired Immunodeficiency Syndrome; Antimicrobial Cationic Peptides; Candidiasis, Vulvovaginal; Cathelicidins; Cervix Uteri; Defensins; Female; Histones; Humans; Immunity, Innate; Lactoferrin; Leukocyte L1 Antigen Complex; Muramidase; Proteinase Inhibitory Proteins, Secretory; Proteins; Trichomonas Vaginitis; Vagina; Vaginosis, Bacterial

Iron is an essential nutrient for Trichomonas vaginalis and is acquired via highly specific receptor-mediated mechanisms from the host. Responses of T. vaginalis to conditions of iron limitation or iron excess were analysed in order to determine whether iron levels in the growth medium regulate certain properties of the parasite. When compared with organisms grown in excess iron, iron limitation resulted in greater than or equal to 80% lower rates of protein synthesis and greater than or equal to 3-fold decreases in cell densities. These parasites also exhibited generation times of approximately 10 hours, 2.5-fold longer than organisms grown in the usual complex medium. Iron-restricted growth also resulted in increased binding of lactoferrin by trichomonads, which paralleled elevated expression of the lactoferrin-binding receptor protein having a relative molecular mass of 136,000 daltons (136 kDa). A Mr 126 kDa protein was concomitantly repressed in low-iron-grown parasites. The greater amounts of lactoferrin bound by iron-depleted T. vaginalis organisms corresponded with both the expression of additional receptors onto trichomonal surfaces and increased affinity of the receptor for the lactoferrin molecule. Finally, immunoblot analysis of parasites grown under high- and low-iron conditions using sera from patients with trichomoniasis further revealed the synthesis by T. vaginalis of at least 19 iron-regulated immunogens, and patients' sera also detected the lactoferrin receptor. These data not only show the overall importance of iron to the biology of this protozoan, but illustrate the in vivo iron modulation of gene expression of the biofunctional lactoferrin receptor and other immunogens.

Topics: Animals; Antigens, Protozoan; Electrophoresis, Polyacrylamide Gel; Female; Gene Expression Regulation; Humans; Iron; Lactoferrin; Protein Binding; Protozoan Proteins; Receptors, Cell Surface; Time Factors; Trichomonas vaginalis; Trichomonas Vaginitis