Relationship between Candida albicans Virulence during Experimental Hematogenously Disseminated Infection and Endothelial Cell Damage In Vitro

Abstract

Candida albicans must penetrate the endothelial cell lining of the vasculature to invade the deep tissues during a hematogenously disseminated infection. We compared 27 C. albicans mutants with their wild-type parent for their capacity to damage endothelial cells in vitro and cause a lethal infection in mice following tail vein inoculation. Of 10 mutants with significantly impaired capacity to damage endothelial cells, all had attenuated virulence. Therefore, the endothelial cell damage assay can be used as a screen to identify some virulence factors relevant to hematogenously disseminated candidiasis.During the initiation of hematogenously disseminated candidiasis, blood-borne organisms must adhere to and penetrate the endothelial cell lining of the blood vessels to invade the deep tissues. One mechanism by which Candida albicans can penetrate the vascular endothelium is by damaging and eventually killing the endothelial cells. Damaged endothelial cells detach from the basement membrane, leaving gaps through which the organism can invade. Also, the exposed basement membrane can be avidly bound by additional organisms (18).C. albicans damages human vascular endothelial cells in vivo and in vitro (5,10,17,25). Maximal endothelial cell damage (ECD) occurs in vitro when C. albicans adheres to and invades the endothelial cells and then secretes lytic enzymes (2,10,11,13,16). Moreover, some C. albicans mutants with filamentation defects cause significantly less ECD than the wild-type parent strain (24). These filamentation mutants also have attenuated virulence in various experimental models of infection (reviewed in reference 23). We hypothesized that the in vitro assay for C. albicans-induced ECD (ECD assay) can serve as a model for certain aspects of host-pathogen interactions in vivo, such as the ability of the organism to adhere to, invade, and injure host cells. This hypothesis predicts that some mutants with virulence defects will be defective in the ECD assay. The goal of the present study was to investigate this prediction.C. albicans strains. The genotypes and sources of the C. albicans strains used here are listed in Tables 1 and 2. Each strain was grown overnight in yeast nitrogen base broth (Difco, Detroit, Mich.) supplemented with 2% glucose (wt/vol) at 20°C on a rotating drum. The blastospores were harvested by centrifugation, washed with phosphate-buffered saline, enumerated with a hemacytometer, and suspended in RPMI 1640 medium (Irvine Scientific, Santa Ana, Calif.).ECD assay. We used our standard 51 Cr release ECD assay to determine the abilities of mutants of C. albicans to damage endothelial cells in vitro (24). The ECD assay was performed in 96-well tissue culture plates (Corning Inc., Acton, Mass.) with endothelial cells isolated from human umbilical cord veins, as described previously (24). The inoculum was 4 ϫ 10 4 organisms per well, and the organisms were incubated with the endothelial cells for 3 h in 5% CO 2 at 37°C. At the end of the incubation period, the wells were examined with an inv...

Candida Species Contamination of Preservation Fluid—Outcome of Renal Transplantation in 6 Patients

“…24,25 Our affected patients showed clinical presentations similar to those previously described in the literature: some patients have an abrupt onset with hypovolemic shock requiring emergency surgery, while others have a more indolent course with fever or worsening renal function and imaging techniques revealing structural arterial lesions. 6e9, 21,22 The long evolution period could be considered important to allograft salvage, even though Bracale et al have reported disappointing outcomes: from 6 patients with large anastomotic pseudoaneurysm, 5 had open repair and 1 stent grafting.…”

Candida albicans Als3, a Multifunctional Adhesin and Invasin

“…C. albicans must invade oral epithelial cells and endothelial cells in order to damage these cells in vitro (15,43). Moreover, C. albicans mutants with impaired capacity to invade and damage host cells in vitro frequently have attenuated virulence in murine models of oropharyngeal and hematogenously disseminated candidiasis (12,39,43,51,61). These data suggest that the capacity of C. albicans to invade and damage host cells is an important virulence attribute.…”

New signaling pathways govern the host response to C. albicans infection in various niches

“…During HDC, this organism invades endothelial cells in order to escape from the vasculature and infect the deep tissues. The observation that invasion-defective C. albicans mutants display attenuated virulence in murine models of OPC and HDC is evidence of the critical importance of invasion to virulence (Phan et al 2000;Sanchez et al 2004;Park et al 2005;Chiang et al 2007). Invasion into both cell types occurs in part by endocytosis, which is induced when the C. albicans invasins Als3p and Ssa1p interact with receptors expressed on the surface of endothelial and epithelial cells (Phan et al 2007;Sun et al 2010).…”