白色念珠菌胃癌株对细胞粘附作用的研究

研究白色念珠菌 (candidaalbicans)正常人口腔株与胃癌株对口腔粘膜细胞及肺上皮细胞的粘附性能。将白色念珠菌与正常人口腔颊粘膜细胞或培养的人肺上皮细胞于 37℃温育一定时间后 ,计算每个细胞粘附白色念珠菌数。白色念珠菌胃癌株对两类细胞粘附能力均较正常人口腔株强 ,其差异有显著性 (p <0 .0 1)。粘附性是致病菌侵袭力的重要机制 ,粘附性增强是白色念珠菌由正常微生物群成员转变为条件致病菌的重要条件。     

Correlative relationship between adherence of Candida albicans to human vaginal epithelial cells in vitro and candidal vaginitis

This study investigated whether a correlation exists between predisposition to candidal vaginitis and adherence of Candida albicans to vaginal epithelial cells in vitro. Vaginal epithelial cells from 120 fecund women who were pregnant and/or diabetic had a greater propensity to bind C. albicans than did 71 oral contraceptive users and 75 non-pregnant, non-diabetic controls. The highest level of adherence occurred in pregnant diabetic women. Among 48 non-diabetic postmenopausal females, C. albicans adherence was lower than for fecund controls, but it was higher for cells from 33 postmenopausal diabetic women. The hormonal status of the fecund and postmenopausal women was assayed cytologically by the Karyopyknotic and Maturation Indices, which determine the ratios of superficial, intermediate and parabasal vaginal epithelial cells. Our findings point to increased C. albicans adherence in situations where there is an increase in the number of intermediate epithelial cells: pregnancy, the first or fourth weeks of the menstrual cycle, or diabetes. The adherence of 41 C. albicans isolates from patients with vaginitis was significantly higher than that of 36 isolates from asymptomatic carriers.     

阻断白色念珠菌粘附口腔膜上皮细胞的实验研究

白色念珠菌的粘附与其表面甘露糖结构有关,为探讨阻断粘附的方法,我们采用体外法测定其对口腔上皮细胞的粘附数量,显示：白色念珠菌粘附感染上皮细胞后,甘露糖可以在一定程度上减少粘附,绿慕安及刀豆素A可以有效地减少粘附。提示甘露糖及绿慕安可能有助于治疗白色念珠菌感染。     

白色念珠菌粘附口腔粘膜上皮细胞配体的初步研究

目的：研究白色念珠菌对口腔粘膜上皮细胞的粘附配体,方法：采用体外法测定白色念珠菌对口腔上皮细胞的粘附数量,结果：D－甘露糖预作用于上皮细胞之后,可以使白色念珠菌粘附下降,刀豆素A及绿慕安预作用于白色念珠菌,可以减少白色念珠菌对上皮细胞的粘附,结论：白鬼念珠菌粘附感染与其表面甘露糖结构有关。     

Monoclonal antibodies directed against extracellular matrix proteins reduce the adherence of Candida albicans to HEp-2 cells

The presence of the extracellular matrix (ECM) proteins collagen types I and IV, laminin and fibronectin on the surface of HEp-2 cells was confirmed by flow cytometry using monoclonal antibodies. Monoclonal antibodies directed against these ECM proteins reduced the adherence of C. albicans ATCC 44990 to HEp-2 cells, the greatest reductions being evident in assays which incorporated anti-collagen type IV monoclonal antibody. The ability of sugaramines to inhibit the adherence of C. albicans to a variety of cell types has been demonstrated previously and the most significant reduction in C. albicans – HEp-2 adherence was in assays which incorporated 0.2M galactosamine. The combination of anti-collagen IV monoclonal antibody and galactosamine reduced the adherence of C. albicans to HEp-2 cells by approximately 70% (p < 0.05). This revised version was published online in June 2006 with corrections to the Cover Date.     

Induction of salivary antibodies to inhibit Candida albicans adherence to human epithelial cells by tonsillar immunization in rabbits

To examine the possibility of a vaccine for Candida albicans infection in the oral cavity, we induced salivary antibodies by immunization of killed-C. albicans ATCC 18804 on the palatine tonsils of rabbits. The enzyme-linked immunosorbent assay reaction of salivary antibodies was high against C. albicans serotype A. The saliva antibodies greatly inhibited C. albicans adherence to cloned epithelial cells from human gingiva. Tonsillar immunizations of C. albicans ATCC 18804 induce salivary antibodies that prevent C. albicans adherence to epithelial cells, and thus should prove useful in the prevention of oral candidiasis caused by C. albicans serotype A.     

In vitro effect of carbohydrates and enteric bacteria on adherence of Candida albicans

The adherence of Candida albicans to any cell is considered essential in the process that leads to colonization. Our objective in this study was to evaluate the effect of different carbohydrates and the presence of lactobacilli and Escherichia coli on the in vitro adherence of Candida albicans. The adherence to buccal epithelial cells was higher when growing at concentrations of galactose of 50, and 200 mM, as well as 50, 200, and 500 mM of sucrose, and 500 mM of mannose, compared with that obtained when growing in Sabouraud dextrose broth (p < 0.01). The presence of other microorganisms, such as Lactobacillus acidophilus and L. casei, caused a decrease in the in vitro adherence of C. albicans to buccal epithelial cells (p < 0.05), whereas E. coli did not modify this adherence at all.     

Decrease in adherence of bacteria and yeasts to human mucosal epithelial cells by noxythiolin in vitro

Adherence of buccal and vaginal isolates of Candida albicans to buccal epithelial cells and the adherence of urine isolates of Escherichia coli and Staphylococcus saprophyticus to uroepithelial cells was quantified by light microscopy. The antimicrobial agent noxythiolin reduced the adherence of these micro-organisms in both exponential and stationary growth phases. Adherence of both the blastospore and pseudohyphal forms of C. albicans was reduced. Treatment of epithelial cells and/or micro-organisms with noxythiolin resulted in decreased adherence. No anti-adherence effect was observed with formaldehyde and N-methylthiourea, the degradative products of noxythiolin.     

Reduced adherence of micro-organisms to human mucosal epithelial cells following treatment with Taurolin, a novel antimicrobial agent

Taurolin, a non-antibiotic antimicrobial agent, significantly reduced the adherence of buccal and vaginal strains of Candida albicans blastospores and urine isolates of Escherichia coli and Staphylococcus saprophyticus to epithelial cells. Light microscopy and radio-isotopic counting methods were used to quantify the adherence of the micro-organisms to either uroepithelial or buccal epithelial cells. A maximum reduction in adherence of approximately 65% was obtained. The anti-adherence capacity was time-dependent, requiring a contact time of 30 min to achieve maximum effect. Taurolin at sub-minimum inhibitory concentrations (MIC) significantly reduced the adherence of Candida and E. coli. A concentration slightly higher than the MIC was required for Staph. saprophyticus. Treatment of either epithelial cells or micro-organisms with Taurolin resulted in reduced adherence of microorganisms.     

Influence of temperature and pH on the in vitro adherence of Candida albicans.

Yeast adherence to epithelial cells is a very important step in colonization and infection caused by these opportunistic pathogens. This phenomenon may be modified in vitro by many factors. The aim of this work was to find out how variations in pH and temperature modify the in vitro adherence of Candida albicans to epithelial cells. We worked with epithelial buccal cells and a yeast strain according to Gibbons and Van Houte technique with slight modifications. In the first assay, adherence at 28 degrees C and 37 degrees C, and three pH values, 6, 7.2 and 8.4 were simultaneously studied. We did not find significant variations in adherente capacity, but a slight increase was detected at pH 7.2 and 37 degrees C. In the second assay, temperature was fixed at 37 degrees C and four pH values were studied: 3, 4, 5, and 7.2. We find a highly significant difference (p < 0.001) between adherente at pH = 7.2 with respect to the other pH values. According to these results C. albicans adherence to epithelial buccal cells, in vitro, is produced at 37 degrees C and pH 7.2 in optimal conditions.     

Reduced adherence of micro-organisms to human mucosal epithelial cells following treatment with Taurolin, a novel antimicrobial agent

Taurolin, a non-antibiotic antimicrobial agent, significantly reduced the adherence of buccal and vaginal strains of Candida albicans blastospores and urine isolates of Escherichia coli and Staphylococcus saprophyticus to epithelial cells. Light microscopy and radio-isotopic counting methods were used to quantify the adherence of the micro-organisms to either uroepithelial or buccal epithelial cells. A maximum reduction in adherence of approximately 65% was obtained. The anti-adherence capacity was time-dependent, requiring a contact time of 30 min to achieve maximum effect. Taurolin at sub-minimum inhibitory concentrations (MIC) significantly reduced the adherence of Candida and E. coli. A concentration slightly higher than the MIC was required for Staph. saprophyticus. Treatment of either epithelial cells or micro-organisms with Taurolin resulted in reduced adherence of microorganisms.     

Experimental study of the effect of corticosteroid preparations on the adhesion of Candida genus fungi to the epitheliocytes of mucous membranes

The effect of corticosteroids on the adherence of Candida cells to epithelial cells was studied with the use of the original modification of the in vitro adherence assay. The administration of hydrocortisone acetate to mice resulted in the increased adherence of the pathogenic fungi to epithelial cells: after 10-day hormone treatment the adherence number and the adherence index increased, respectively, to 230% and 360% of control values. After 20-day treatment these characteristics increased, respectively, to 260% and 700%. The adherence of C. albicans to vaginal epithelial cells in female mice receiving corticosteroids increased in comparison with that in the control animals at estrus: the adherence number increased to 220% and the adherence index, to 470% of the level observed in the controls.     

Adherence of Candida albicans to buccal and vaginal epithelial cells: ultrastructural observations

The adherence of Candida albicans to human buccal and vaginal epithelial cells was studied by transmission electron microscopy. Adherence to epithelial cells was confirmed by both a radiometric assay as well as direct microscopic examination of stained cell preparations. Ultramicroscopic preparations revealed that yeast cells were closely appressed to epithelial cell surfaces and were often partially enclosed within phagocyticlike invaginations of the epithelial cells. A murine model of vaginitis caused by C. albicans was also used to study adherence to epithelial cells and to follow the course of colonization. Ultramicroscopic preparations of murine vaginal tissue revealed that within 2 h postinfection, yeast cells could be seen adhering to epithelial cells. At 6 h postinfection, hyphae and yeast cells were not only found on the epithelial cell surface but also within the submucosal tissue. When observed on the epithelial cell surface, Candida cells were either attached to host cells, or when infected tissue was stained with ruthenium red, Candida cells were observed on the epithelial surface embedded within an electron-dense matrix. Fungal elements were abundant in the submucosa at 24 h postinfection and were still observed on the epithelial cell surface; all of this was accompanied by an inflammatory response.     

Effect of various components of the fungal cell wall on adhesion of Candida albicans to the mouth mucosa epithelium in vitro]

An influence of mannan++, its component methyl-D-mannopyranoside+ and N-acetylglucosamine on in vitro adhesion of Candida albicans strains to buccal mucosal epithelium was studied. These substances inhibited adhesion when added to adherence test in a concentration of 10 mg/ml and 25 mg/ml despite whether were added to the test incubation medium or when preincubated with fungi or epithelial cells. Preincubation of fungal cells and epithelial cells with mannan had no influence on attachment; preincubation of epithelial cells with methyl-D-mannopyranoside+ and N-acetylglucosamine decreased adherence significantly. On the other hand preincubation of fungal calls with methyl-D-mannopyranoside+ increased their adhesive properties, having no influence on adherence after preincubation of fungi with N-acetylglucosamine.     

Adherence of Candida albicans and Candida dubliniensis to buccal and vaginal cells

Twenty-seven Candida albicans strains and 26 Candida dubliniensis strains, isolated from HIV patients, were tested for their adherence to buccal and vaginal epithelial cells. Both species showed important levels of adhesion to buccal and vaginal epithelial cells, although C. albicans showed the highest levels of adhesion. These results suggest that both Candida species are well adapted, in terms of adhesion capability, to the oral and vaginal environment.     

Inhibition of Candida adhesion to buccal epithelial cells by an aqueous extract of Allium sativum (garlic)

The effect of pre-incubation of either Candida or buccal epithelial cells (BEC) with different concentrations of aqueous garlic extract (AGE) was investigated, as well as the effect of mouth rinse with AGE on the adhesion of yeast to BEC. Adhesion of Candida spp. to BEC was significantly reduced after both short and long time exposure of yeast to AGE. A similar inhibition of adherence was observed upon preincubation of BEC with AGE. The adherence-inhibition activity of AGE treatment was antagonized by thiols such as L-cysteine, glutathione and 2-mercaptoethanol. In addition, germ-tube formation was suppressed when C. albicans cells were pretreated with AGE. There was a significant reduction in the adherence of yeasts to BEC collected immediately or 15 min after an oral rinse with AGE. No statistical significance in the adhesion of BEC collected 30 min after oral rinse with AGE and control BEC was observed. The diminished adherence of C. albicans to BEC after exposure to various concentrations of garlic may have clinical relevance.     

Inhibition of Candida adhesion to buccal epithelial cells by an aqueous extract of Allium sativum (garlic)

The effect of pre-incubation of either Candida or buccal epithelial cells (BEC) with different concentrations of aqueous garlic extract (AGE) was investigated, as well as the effect of mouth rinse with AGE on the adhesion of yeast to BEC. Adhesion of Candida spp. to BEC was significantly reduced after both short and long time exposure of yeast to AGE. A similar inhibition of adherence was observed upon pre-incubation of BEC with AGE. The adherence-inhibition activity of AGE treatment was antagonized by thiols such as l-cysteine, glutathione and 2-mercaptoethanol. In addition, germ-tube formation was suppressed when C. albicans cells were pretreated with AGE. There was a significant reduction in the adherence of yeasts to BEC collected immmediately or 15 min after an oral rinse with AGE. No statistical significance in the adhesion of BEC collected 30 min after oral rinse with AGE and control BEC was observed. The diminished adherence of C. albicans to BEC after exposure to various concentrations of garlic may have clinical relevance.     

Morphological specificity of yeast and filamentous Candida albicans forms on surface properties

Physicochemical surface properties of Candida albicans were assessed from microbial adhesion to human epithelial cells and to octane droplets. The adherence of cells demonstrated the occurrence of morphological specificity for these adhesion assays. Filamentous forms exhibited adherence third times higher compared to budding forms, while their electrophoretic mobilities were comparable. Force measurements performed on filamentous form by AFM demonstrated that such adhesion was associated with microfibrillar surface structure.     

Cell surface hydrophobicity-associated adherence of Candida dubliniensis to human buccal epithelial cells

Microbial adherence to mucosal surfaces is an important first step in the initiation of the pathogenic process in the oral cavity. Candida albicans, the most adherent and pathogenic Candida species, utilizes a variety of mechanisms to adhere to human tissues. Although the strongest mechanism of adherence involves mannoprotein adhesins on C. albicans, cell surface hydrophobicity (CSH) plays an important role in the adherence process by providing hydrophobic interactions that turn the initial attachment between the yeast and a surface into a strong bond. Recent cell wall analytical and comparative studies showed that, Candida dubliniensis, unlike C. albicans, possesses cell surface variations that allow it to be constantly hydrophobic, regardless of growth temperature. Based on these observations, the present study was designed to compare the adherence abilities of C. dubliniensis and C. albicans to pooled human buccal epithelial cells (BEC), in regards to their cell surface hydrophobicity. Ten C. albicans and nine C. dubliniensis isolates, as well as the C. albicans hydrophobic variant A9V10 were evaluated for adherence with BEC using visual aggregation in the wells of a microtiter plate and microscopic examination. All 11 C. albicans isolates failed to show adherence to BEC, visually or microscopically, when grown at 37 degrees C. The same isolates, however, showed significant increase in aggregation and microscopic adherence to BEC when grown at 25 degrees C. All C. dubliniensis isolates tested and the A9V10 C. albicans hydrophobic variant resulted in visual aggregation and adhered to BEC when grown at either temperature. The findings from this study show that, based on comparative adherence results and growth temperature changes, C. dubliniensis seems to have greater adherence to BEC than do typical C. albicans strains and that hydrophobic interactions seem to be the mechanism of adherence involved. Although many questions remain to be answered regarding the clinical implications of this observed in vitro enhanced adherence of C. dubliniensis to human BEC, these findings support the establishment of this novel species as a clinically significant yeast.     

Adherence and receptor relationships of Candida albicans.

The cell surface of Candida albicans is composed of a variety of polysaccharides such as glucan, chitin, and mannan. The first two components primarily provide structure, while the mannan, often covalently linked to protein, constitutes the major antigen of the organism. Mannoproteins also have enzymatic activity (acid protease) and ligand-receptor functions. The complement receptors of C. albicans appear to be mannoproteins that are required for the adherence of the organism to endothelial cells. This is certainly true of the CR3-like protein of C. albicans. Proof that the CR3 is the Candida receptor for endothelial cells is derived from two observations. First, mutants lacking CR3 activity are less adherent in vitro and, in fact, less virulent. Second, the ligand recognized by the CR3 receptor (C3bi) as well as anti-CR3 antibodies blocks adherence of the organism to endothelial cells. The CR2 of C. albicans appears to promote the adherence of the organism to plastic substrates. Unlike the CR2 of mammalian cells, the Candida CR2 recognizes ligands containing the RGD sequence of amino acids in addition to the C3d ligand, which does not contain the RGD sequence. There is uncertainty as to whether the Candida CR2 and CR3 are, in fact, different proteins. A mannoprotein has also been described as the adhesin for epithelial cells. In this case, the receptor has a lectinlike activity and recognizes fucose- or glucosamine-containing glycoproteins of epithelial cells, depending on the strain of C. albicans. The oligosaccharide component of the receptor is probably not involved in ligand recognition and may serve to stabilize the receptor. However, the oligosaccharide factor 6 epitope of mannan may also provide adhesin activity in the recognition of epithelial cells. Mannoproteins can be extracted from cells by a number of reagents. Zymolyase, for instance, tends to remove structural mannoproteins, which contain relatively little protein and are linked to glucan. Reagents such as dithiothreitol, on the other hand, tend to extract mannoproteins containing higher amounts of protein that appear to have receptor function. The mannoproteins of C. albicans are dynamically expressed and may be growth phase and growth form specific.