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Colonization of Candida albicans on oral surfaces can serve as a reservoir for disseminated infections, such as aspiration pneumonia and gastrointestinal infection, particularly in the immunocompromised host. Therefore, the aim of this study was to investigate the effects of salivary and serum pellicles on C. albicans, Streptococcus mutans, S. sanguis, Lactobacillus and Actinomyces colonization on type I collagen, a major organic component of periodontal ligaments. The colonization potential of two isolates each of C. albicans, S. mutans and S. sanguis, and a single isolate each of Lactobacillus and Actinomyces to uncoated (control), saliva-coated or serum-coated type I collagen plates (surface area 143 mm(2), Cell Disk; Sumitomo, Tokyo, Japan) was examined using a bioluminescent adenosine triphosphate assay based on firefly luciferase-luciferin system. The results revealed that with mutans streptococci, a saliva pellicle was significantly more effective in promoting bacterial colonization compared with the pellicle-free collagen disc, and the serum-coated sample significantly inhibited the colonization of streptococci (anova; P < 0b01). In contrast, in the case of C. albicans, Lactobacillus and Actinomyces isolates, a serum pellicle was significantly more effective in promoting the colonization, followed by saliva pellicle and uncoated specimen (anova; P < 0b01). These results suggested that crevicular fluid rich in seruminous components would promote the colonization of Candida, Lactobacillus and Actinomyces on type I collagen as opposed to streptococci which showed greater avidity to saliva-coated collagen.

Oral epithelial cells significantly influence host inflammatory responses against Candida albicans in oropharyngeal candidiasis. We sought to elucidate the pattern of interleukin-8 (IL-8) expression by oral epithelial cells, which may function as an early innate immune system mediator during C. albicans infection. Primary human gingival epithelial cells (HGECs) were co-cultured with either viable or heat-killed C. albicans or fungal-derived substances, such as fungal secretion, fungal extracted proteins, and alpha-mannan. In vitro cell injury due to viable C. albicans was detectable by an adenosine triphosphate-based assay after 12h of infection. Prior to the detection of cell injury, HGECs clearly increased production of interleukin-1 alpha (IL-1alpha) and IL-8 in response to C. albicans infection, as determined by enzyme-linked immunosorbent assay and real-time reverse transcription PCR. High concentrations of a suspension of heat-killed yeast and all fungal-derived substances examined also stimulated IL-8 production by HGECs. Incubation with neutralizing anti-IL-1alpha or anti-intercellular adhesion molecule-1 (ICAM-1) monoclonal antibodies (mAb) significantly inhibited C. albicans-induced IL-8 production. Use of mAbs against both IL-1alpha and ICAM-1 produced a more significant combined inhibitory effect on the IL-8 production than either mAb alone. These findings indicate that HGECs synthesize increased levels of IL-1alpha and IL-8 in response to viable C. albicans before cell injury is manifested. Fungal cell-wall components, alpha-mannan, and fungal protein extracts are all sufficient to increase IL-8 production. The molecular mechanisms governing the IL-8 response of HGECs to C. albicans infection likely involve multiple converging signal transduction pathways, including those mediated by IL-1alpha and ICAM-1 activation.

Increased induction of interleukin 8 (IL-8) and intercellular adhesion molecule 1 (ICAM-1) by oral epithelial cells may play a role in the host defense mechanism in oropharyngeal candidiasis; however, little is known about the expression feature of these molecules on human gingival epithelial cells (HGECs) during Candida albicans infection. In this report we present evidence that neutralization with antibody against ICAM-1 inhibited both the adherence of C. albicans to HGECs and the Candida-induced production of IL-8, suggesting a role for ICAM-1 in recognition and signaling in HGECs to express IL-8 upon infection with C. albicans.

Objective: Peptide antibiotics are considered a new class of antifungal agents. Of these, an alpha-helical, cationic peptide termed Dhvar 4, a relative of salivary histatin has been shown to be an antifungal of relatively high potency. Similarly, lactoferricin B (LFB) and a derivative thereof, LFB(17-30), disrupts the fungal cell membrane and acts against Candida albicans. As Dhvar 4 and LFB(17-30), exhibit almost identical amino acid sequences at their C-terminal, we hypothesized that laboratory synthesis of peptides with an alpha-helical structure and having similar amphipathic properties could lead to products with candidacidal activity. Hence, three such peptides - JH8194, JH8195 and JH 8944, were synthesized and their antifungal properties compared with recognized antifungals LFB, LFB(17-30), human lactoferricin (LFH), Histatin-5 and Dhvar 4, against two isolates of C. albicans., Materials and Methods: The antifungal agents were synthesized and their secondary structures evaluated according to a previously described protocol of Situ and Bobek (2000)Antimicrob Agents Chemother44: 1485-1493. The C. albicans strains were oral isolates from a human immunodeficiency virus-infected (isolate A2) and a healthy (A6) individual. A standard concentration of yeasts was exposed to a range of dilutions of the agents for a specific duration and the cell death (viability) in terms of the resultant colony forming units ml(-1) was quantified., Results: Dhvar 4, showed the most alpha-helical propensity, and was the least fungicidal while LFB and LFB(17-30) showed the highest antifungal potential, and demonstrated total kill of A6, and A2 at 5 and 10 microM concentrations, respectively whilst LFH killed both isolates at a l0 microM concentration. Of the three new synthetic peptides, JH 8194 was the most potent (total kill of A6/A2 strains at 1.25/2.5 microM), followed by JH 8195 (total kill of A6/A2 strains at 5/10 microM while JH 8944 was the least potent as a 25 microM concentration was required to kill either strain of Candida. On further analyses of the relationship between pI value of the peptides and their anticandicidal activity, a significant positive correlation was noted. In order to rule out a cytotoxic effect of the new synthetic peptides we compared the fungicidal and hemolytic activities under similar incubation conditions using freshly isolated erythrocytes and all three peptides exhibited no detectable hemolysis upto an concentration of 100 microM in contrast to the polyene antifungal amphotericin B that elicited significant initiation of hemolysis at a concentration of 5.0 microM., Conclusion: Our data suggest that laboratory synthesis of agents with an alpha-helical structure and having amphipathic properties similar to known, natural antifungal agents may be a promising avenue to generate products with improved antifungal activity.

The adherence and dissociation of Candida albicans, C. tropicalis, Streptococcus mutans and S. sanguis to six substrates including hydroxylapatite (HAP) which exhibit various hydrophobicity, was examined by the use of a bioluminescent adenosine triphosphate (ATP) assay. Dissolution of HAP by C. albicans or S. mutans was determined spectrophotometrically by the use of o-cresolphthalein complexone. In the adherence of C. tropicalis, S. mutans and S. sanguis, the amount of adherent cells correlated with the hydrophobicity of the substrates. In contrast, the adherence of C. albicans to HAP was extraordinary high, although the adherence of the fungi also correlated with the hydrophobicity of the substrates, except for HAP. The yeasts attached to HAP was effectively removed by high concentration of either phosphate or calcium ions. The amount of calcium-release from HAP caused by C. albicans and S. mutans was 113 microg ml(-1) (final pH = 3.45), and 5.4 microg ml(-1) (final pH 4.81), respectively and the maximum growth of C. albicans and S. mutans was 10(7) cfu ml(-1) and 7.4 x 10(12) cfu ml(-1), respectively. The results, taken together, suggest that C. albicans adhere to HAP specifically through electrostatic interaction, and that, in a much smaller number (1.0/7.4 x 10(5)), C. albicans possesses the ability to dissolve HAP to a greater extent (approximately 20-fold) when compared with S. mutans.

Candidal colonization and subsequent biofilm formation on denture materials are important in the development of pathogenesis, such as denture stomatitis. Routine use of denture cleansers is one of the most effective methods of denture plaque control, although the incompatibility of soft liners and denture cleansers cause damage to the materials. The present study, biofilm formation of Candida albicans on the surfaces of soft denture lining materials, immersed in denture cleansers for 180 days were studied. Seven commercially available soft denture lining materials, were artificially deteriorated by immersion into three commercially available denture cleansers for 180 days, and subsequent fungal growth and biofilm formation were studied by measuring pH of the media and by the use of adenosine triphosphate (ATP) analysis. Fungal biofilm formation on the deteriorated soft liners varied depending upon the combination of the soft liners and denture cleansers. Several combinations of soft liners with denture cleansers exhibited the significantly high colonization capacity as compared with each sample immersed in distilled water, used as individual controls. The relationship between the biofilm formation on the samples of each material and the surface roughness of the soft lining materials was analyzed. However, no significant correlation was observed. The results, taken together, suggested that fungal colonization could be predominantly regulated by the combination of lining material with denture cleansers. In clinical terms, our findings suggests that daily cleansing of soft lining materials with mismatched denture cleansers promoted the subsequent biofilm formation of fungi on the materials.

We developed an in vitro ATP assay technique to extract cellular and fungal ATP separately, which allowed to evaluate quantitatively the adhesion of the yeasts to monolayers of human gingival epithelial cells. Thirteen isolates of Candida spp. representing three species (i.e. Candida albicans, C. tropicalis and C. glabrata) were used in the present study. When the adherent capacity of the Candida species was compared, C. albicans exhibited highest capacity of adherence to gingival epithelial cells, followed by C. tropicalis, and C. glabrata was the lowest [analysis of variance (ANOVA), P < 0.01]. The germ tubes of C. albicans exhibited significantly higher adherence capacity than their blastoconidia cells (ANOVA, P < 0.01), which was not observed with a C. albicans isolate, defect of germ tube formation. Our results suggested that the adherence of C. albicans is promoted by germ tube formation and may play an important role in the pathogenesis of the fungus.

Several recent reports imply the possibility of cariogenicity and periodontal disease linked to denture plaque containing Candida albicans. Adhesion of oral bacteria and Candida species to the extracellular matrix, such as type I collagen, fibronectin and denatured type I collagen, was examined by using adenosine triphosphate (ATP) analysis. The adhesion of C. albicans to intact and denatured type I collagen was significantly greater than those of oral bacteria and other species of Candida. This result suggests that C. albicans possesses the ability to adhere specifically to extracellular matrix, as compared with other Candida species or oral bacteria.

The effects of four liquid components of denture acrylic resin on host cell activity and fungal adhesion were investigated in this study. The low concentration (1 micromol l(-1)) of the liquid components caused no change in the activities and morphologies of the gingival fibroblast cells, compared with control and dimethylsulphoxide-exposed cells. However, when the cells were exposed to high concentrations (1 mmol l(-1)) of benzqyl peroxide, morphological change was observed, implying that the exposure of the cells to high concentrations of the liquid components of denture acrylic causes the loss of adhesion proteins from the cells. Thus the amount of Candida adhesion to human gingival cells was analysed, and the adherence of fungi to the cell was significantly reduced when the cells were pre-exposed to methyl methacrylate, hydroquinone and benzoyl peroxide at a concentration of 1 micromol l(-1) (P < 0.01), which did not affect either the cell viability or the cell morphology. These results, taken together, suggested that the renewal of dentures could be a possible therapeutic and/or preventive aid for oral candidosis in denture-wearing patients.

Statement of Problem: Oral surfaces, including the denture-fitting surface, may serve as a reservoir for disseminated candidal infections, particularly in immunocompromised hosts such as patients with AIDS. Histatins are a group of small, cationic antifungal peptides present in human saliva. There is limited information on the antifungal activity of peptides against Candida albicans isolates from HIV-positive patients., Purpose: This study investigated the fungicidal effects of histatin-5 against oral isolates of C. albicans from HIV-positive and HIV-negative patients., Material and Methods: An isolate of C. albicans from each of 2 HIV-positive patients (both male) and 3 HIV-negative patients (2 male and 1 female) was obtained. American Type Culture Collection 90028 served as a reference strain. All isolates were identified with sugar assimilation tests and the germ tube test. Fungicidal assays were performed on exponential C. albicans cells in the presence or absence of 0.315 to 50 microm of histatin-5. Numerical data were subjected to 1-way analysis of variance and Tukey's multiple range test (P<.05)., Results: Histatin-5 (50 microm) killed more than 95% of C. albicans isolates from HIV-negative patients and more than 90% of isolates from the reference strain. The same treatment induced 75.3% and 66.1% loss of viability in C. albicans isolates taken from HIV-positive patients (A1 and A2 cells, respectively). The difference between the fungicidal effects in the HIV-positive and HIV-negative groups was significant. (P<.05)., Conclusion: Within the limited population of this study, C. albicans isolates from the oral cavities of HIV-positive patients were less sensitive to histatin-5 than oral isolates from HIV-negative patients.

An inhibition assay of Candida albicans adhesion to gelatin-immobilized membranes was compared with that to intact type I collagen-immobilized membranes using an arginine-glycine-aspartic acid (RGD) containing peptide. As compared with a protein-free membrane, gelatin and collagen significantly enhanced the adherence of C. albicans. The adhesion of the yeast to gelatin was significantly inhibited by the RGD peptides, but not by arginine-glycine-glutamic acid (RGE) peptides. In contrast, attachment to collagen was not inhibited by RGD peptides. These results suggest that the RGD sequence of gelatin and the integrin-like proteins of yeasts may be involved in adherence.

Interactions between bacterial oral flora and Candida albicans are important in denture plaque formation. This study therefore first aimed to quantify the coadherence of C. albicans and bacteria by the use of a bioluminescent adenosine triphosphate (ATP) assay based on the firefly luciferase-luciferin system. The second aim was to examine the effect of i) dietary sugars (used for preculture) and ii) enzymatic digestion of fungi on the coadherence. When yeast was preincubated in yeast nitrogen base medium (YNB) supplemented with 250 mM glucose, the yeast coadhered with all isolates of Streptoccus mutans and Streptococcus sanguis, and no significant coadhesion was observed with the isolates of Streptococcus sobrinus, Streptococcus salivarius, Lactobacillus and Actinomyces. However, when the yeast was precultured in YNB supplemented with 500 mM galactose, the yeast coadhered with S. salivarius and Actinomyces, which was not observed when the yeast was grown in YNB with glucose. In addition, the coadherence of the yeast with the isolates of S. sanguis was significantly reduced. Enzymatic digestion of yeast and a reverse transcription polymerase chain reaction assay revealed that expression of at least two types of proteinaceous adhesins are involved in these phenomena.

In the present study, the growth of a single isolate of Candida albicans on saliva-, serum-coated or protein free (uncoated), thermocycled (4-70 degrees C for 1 min, respectively; 0, 1000 and 10 000 times) 15 commercial maxillofacial materials was investigated, by monitoring pH changes in growth media. The inhibitory effect of the tissue conditioners on fungal growth was analysed using three parameters viz: (i) delay in the onset of the rapid decline in pH (ii) reduction in the rate of pH change and (iii) the pH minima reached. In the case of control materials (non-thermocycled and uncoated), significant antifungal effect was observed with two products. However, the antifungal effect of the materials was significantly reduced both by thermal cycling (Analysis of covariance [ANOVA]; P < 0.01) and a layer of protein coating (saliva, P < 0.05; serum, P < 0.01). When the interrelation between three parameters of fungal growth and the surface hydrophobicity of the materials were analysed, minimum pH of fungal growth on 10 000-thermocycled materials correlated well with the contact angles of the materials (Student t-test, P < 0.01), suggesting that thermocycling process reduced the unpolymerized components of the materials which showed the antifungal effects, resulted in that the cell growth depends on the surface hydrophobicity of the specimens. These results, taken together, suggest that the ageing of the materials and the biological fluids of the host enhanced the fungal growth on maxillofacial materials.

In the present study, the growth of a single isolate of Candida albicans on saliva-, serum-coated or protein free (uncoated), thermocycled (4-70 degrees C for 1 min, respectively; 0, 1000 and 10 000 times) seven commercial soft lining materials were investigated, by adenosine triphosphate (ATP) analysis. In the case of control resilient liners (not thermocycled and uncoated), the fungal colonization appeared to depend upon the type of commercial resilient liner used. Thus, the lowest colonization was observed with fluoric and heat-cured silicone materials, cold-cured silicone materials, except for one product, and heat-cured acrylic resin exhibited the highest colonization capacity, and cold-cured acrylic resilient liners exhibited the intermediate. However, the fungal colonization on the materials was significantly promoted both by thermal cycling (ANOVA, P<0.01) and a layer of protein coating (saliva, P<0.01; serum, P<0.01). These results, taken together, suggest that the ageing of the materials and the biological fluids of the host promote yeast colonization on resilient lining materials.

The analysis of the adherence capacity of fungi to surfaces of both oral tissue and different tissues would be of interest in the fungal dissemination as an oral and systemic pathogen. We developed an in vitro adenosine triphosphate (ATP)-based assay technique to extract the cellular and fungal ATP separately, which allowed the quantitative evaluation of the adhesion of the yeast to monolayers of human gingival epithelial cells (GEC), gingival fibroblasts (GF) and pulmonary fibroblasts (PF). Seven oral isolates of Candida species (three of Candida albicans, three of Candida tropicalis and one of Candida glabrata) were used in the study. The adherent level of the Candida species varied depending on both the isolates and the cell origins, although all the Candida isolates had a significantly higher level of adherence to GEC than to GF except the single isolate of C. tropicalis. Whereas the adherent level of the five isolates to GEC was significantly higher than that to PF, the adherent level of the remaining two isolates of C. tropicalis to GEC was significantly lower than that to PF. These results suggest that candidal adherence to host tissue cells should be regulated in an isolate-dependent and cell-origin-dependent manner, and that the phenomena may be involved in the colonisation and/or dissemination of the fungi. [ABSTRACT FROM AUTHOR]

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Several recent reports imply the possibility of cariogenicity and periodontal disease linked to denture plaque containing Candida albicans. Adhesion of oral bacteria and Candida species to the extracellular matrix, such as type I collagen, fibronectin and denatured type I collagen, was examined by using adenosine triphosphate (ATP) analysis. The adhesion of C. albicans to intact and denatured type I collagen was significantly greater than those of oral bacteria and other species of Candida. This result suggests that C. albicans possesses the ability to adhere specifically to extracellular matrix, as compared with other Candida species or oral bacteria. [ABSTRACT FROM AUTHOR]

Fungicidal effects of histatin-5 against 26 oral isolates belonging to 5 non-albicans Candida species were examined. Fifty μM of histatin-5 killed more than 95% of Candida tropicalis and Candida guilliermondii isolates and more than 90% of Candida parapsilosis and Candida krusei. However, Candida glabrata was less sensitive to the peptide (mean 62.9%). Our results, taken together, demonstrated that histatin-5 possessed the fungicidal activity against Candida species other than C. glabrata. [ABSTRACT FROM AUTHOR]