RESUMEN
It has recently been shown that measurable amounts of complement proteins, C6 and in particular C7, are released from human polymorphonuclear leukocytes (PMNs). The aim of the present study was to investigate the impact of opsonized Candida albicans on this release. Stimulation with opsonized C. albicans led to a rapid and sustained increase of C6 and C7 in the cell culture supernatant beginning within 5 min of placing in co-culture, whereas co-culture with unopsonized C. albicans or C. albicans mock-opsonized with inactivated human serum did not affect the release. In contrast, even after stimulation employing opsonized C. albicans, no release of the complement component C8 and only trace amounts of C9 were detected. The presence of the membrane attack complex (MAC) on C. albicans after opsonization was demonstrated by indirect immunofluorescence. Opsonization of C. albicans with human serum deficient in or depleted of a terminal complement component resulted in only minor stimulation of C6 and C7 release, although C3 deposition on the surface of C. albicans was not affected as determined by direct immunofluorescence. Detailed analyses with inactivated or deficient sera showed that detection of C6 and C7 was not due to insufficient washing of the opsonized yeast prior to co-culture and suggest that only a small proportion of these proteins was derived from the membrane bound and then cleaved off MAC. Thus, these findings imply that MAC on the fungal surface may represent an additional trigger for the release of C6 and C7 from PMNs, suggesting a new role for the terminal complement complex (TCC) on target membranes as modulator of PMN functions locally at the site of inflammation.
Asunto(s)
Complejo de Ataque a Membrana del Sistema Complemento/metabolismo , Proteínas del Sistema Complemento/metabolismo , Neutrófilos/inmunología , Levaduras/inmunología , Candida/inmunología , Candida albicans/inmunología , Supervivencia Celular , Células Cultivadas , Complemento C6/metabolismo , Complemento C7/metabolismo , Técnica del Anticuerpo Fluorescente Indirecta , Humanos , Neutrófilos/metabolismo , Proteínas Opsoninas/inmunología , Saccharomyces cerevisiae/inmunología , Levaduras/metabolismoRESUMEN
The putative virulence factor secreted aspartyl proteinase (SAP) of Candida albicans and the human immunodeficiency virus type 1 (HIV-1) protease both belong to the aspartyl proteinase family. The present study demonstrates that the HIV-1 protease inhibitor Indinavir is a weak but specific inhibitor of SAP. In addition, Indinavir reduces the amount of cell bound as well as released SAP antigen from C. albicans. Furthermore, viability and growth of C. albicans are markedly reduced by Indinavir. These findings indicate that HIV-1 protease inhibitors may possess antifungal activity and we speculate that in vivo SAP inhibition may add to the resolution of mucosal candidiasis in HIV-1 infected subjects.
Asunto(s)
Ácido Aspártico Endopeptidasas/antagonistas & inhibidores , Candida albicans/efectos de los fármacos , Inhibidores de la Proteasa del VIH/farmacología , Proteasa del VIH/efectos de los fármacos , Indinavir/farmacología , Secuencia de Aminoácidos , Ácido Aspártico Endopeptidasas/química , Candida albicans/enzimología , Candida albicans/patogenicidad , Datos de Secuencia Molecular , VirulenciaRESUMEN
Previously, it has been shown that human immunodeficiency virus (HIV)-1 envelope proteins gp160 and gp41 bind to Candida albicans. Whether this interaction affects candidal virulence in vitro was investigated. HIV-1 gp160 or gp120 treatment of C. albicans significantly altered neither growth nor phospholipase activity of the fungus. However, treatment of C. albicans with gp160, but not with gp120, led to an elevation of free and cell-bound aspartate proteinase. In addition, culture supernatants obtained from C. albicans treated with gp160 or gp41, but not with gp120, showed a strong increase in proteinase activity. Finally, C. albicans viable yeast cells treated with gp160 or gp41 and serum were phagocytosed by polymorphonuclear leukocytes to a lesser extent than was C. albicans treated with gp120 and serum or serum alone. These findings suggest that the interaction between HIV-1 gp160 and C. albicans may promote the virulence of C. albicans in HIV-1-positive patients.
Asunto(s)
Candida albicans/metabolismo , Candida albicans/patogenicidad , Candidiasis/patología , Proteína gp120 de Envoltorio del VIH/farmacología , Proteínas gp160 de Envoltorio del VIH/farmacología , Proteína gp41 de Envoltorio del VIH/farmacología , Antígenos Fúngicos/análisis , Antígenos Fúngicos/inmunología , Ácido Aspártico Endopeptidasas/metabolismo , Candida albicans/crecimiento & desarrollo , Candidiasis/inmunología , Candidiasis/metabolismo , Medios de Cultivo Condicionados/química , Medios de Cultivo Condicionados/metabolismo , Endopeptidasas/análisis , Endopeptidasas/metabolismo , Proteína gp120 de Envoltorio del VIH/metabolismo , Proteínas gp160 de Envoltorio del VIH/metabolismo , Proteína gp41 de Envoltorio del VIH/metabolismo , Humanos , Leucocitos Mononucleares/citología , Leucocitos Mononucleares/inmunología , Leucocitos Mononucleares/microbiología , Neutrófilos/inmunología , Proteínas Opsoninas/farmacología , Fagocitosis/inmunología , Fosfolipasas/metabolismo , VirulenciaRESUMEN
Oral candidiasis in human immunodeficiency virus type 1 (HIV-1)-infected persons is believed to be caused by the acquired T lymphocyte immunodeficiency. The direct interaction of C. albicans and HIV-1 in vitro was investigated. Twice as many yeasts adhered to cells transfected with the HIV-1 env gene as they did to controls. HIV-1 rsgp160 and rsgp41 but not rsgp120 were found to bind to Candida albicans via two C3-like regions within gp41. Normal human serum, but not C3-depleted serum, was able to inhibit rsgp41 binding to C. albicans. Vice versa, rsgp160 and rsgp41 were able to block rosetting of C. albicans with iC3b-coated sheep erythrocytes. Binding to C. albicans, and its inhibition by rsgp41 or rsgp160, was confirmed for the whole virus. Therefore, oral candidiasis in HIV-1-infected subjects may be augmented or may even be initiated by direct interaction between C. albicans and HIV-1 or HIV-1-infected cells.