Albicans Inoculation Research Articles

Immunomodulatory drug fingolimod (FTY720) restricts the growth of opportunistic yeast Candida albicans in vitro and in a mouse candidiasis model.

Fingolimod (FTY720) is a drug derived from the fungicidal compound myriocin. As it was unclear whether FTY720 has antifungal effects as well, we aimed to characterize its effect on Candida albicans in vitro and in a mouse candidiasis model. First, antifungal susceptibility testing was performed in vitro. Then, a randomized, six-arm, parallel, open-label trial was conducted on 48 mice receiving oral FTY720 (0.3 mg/kg/day), intraperitoneal C. albicans inoculation, or placebo with different combinations and chorological patterns. The outcome measures of the trial included serum concentrations of interleukin-10 and interferon-gamma, absolute lymphocyte counts, and fungal burden values in the mice's livers, kidneys, and vaginas. Broth microdilution assay revealed FTY720's minimum inhibitory concentration (MIC99) to be 0.25 mg/mL for C. albicans. The infected mice treated with FTY720 showed lower fungal burden values than the ones not treated with FTY720 (p<0.05). As expected, the mice treated with FTY720 showed a less-inflammatory immune profile compared to the ones not treated with FTY720. We hypothesize that FTY720 synergizes the host's innate immune functions by inducing the production of reactive oxygen species. Further studies are warranted to unveil the mechanistic explanations of our observations and clarify further aspects of repurposing FTY720 for clinical antifungal usage.

α-galactosylceramide-stimulated invariant natural killer T-cells play a protective role in murine vulvovaginal candidiasis by Candida albicans.

Vulvovaginal candidiasis is a common superficial candidiasis; however, a host's immunological mechanism against vaginal Candida infection remains unknown. In this study, we aimed to elucidate the effect of iNKT cell activation on vulvovaginal candidiasis. Using a vulvovaginal candidiasis model with estrogenized mice, we evaluated the fungal burden and number of leukocyte infiltrations in the vaginal lavage of wild-type C57BL/6J mice after Candida albicans inoculation. One day before C. albicans inoculation, α-galactosylceramide (the α-GalCer group) or sterile phosphate-buffered saline (the sham group) was intraperitoneally injected into the mice. We also evaluated the level of antimicrobial peptide S100A8 in the vaginal lavage and analyzed the correlation between S100A8 concentration and the number of vaginal leukocyte infiltrations. Moreover, the number of uterine and vaginal immune cells were evaluated using flow cytometry. The number of vaginal leukocyte infiltrations was significantly higher in the α-GalCer group than in the sham group 3 days after C. albicans inoculation. In addition, the fungal burden was significantly lower in the α-GalCer group than the sham group at 7 days after inoculation. In the analysis of S100A8 concentration of vaginal lavage, there were no significant differences between these two groups, although S100A8 concentration and the number of vaginal leukocyte infiltrations were positively correlated in the α-GalCer group. Moreover, the number of vaginal iNKT cells, NK cells and CD8+ T-cells was significantly higher in the α-GalCer group 3 days after inoculation. α-GalCer-stimulated iNKT cells likely play a protective role against vulvovaginal candidiasis.

Studies on the Effectiveness of Ozone Therapy on the Treatment of Experimentally Induced Keratitis with Candida albicans in Rabbits

ABSTRACT Purpose In the present study, antifungal activity of ozonated olive oil (OZO) and ozonated distilled water (ODW) in the treatment of experimentally induced keratitis with C. albicans in rabbits were investigated. Methods The Groups were composed of as 1, 2, 3, 4, 5, 7 (n = 5 rabbits, 10 eyes/in each group) and Group 6 (n = 10 rabbits, 20 eyes/in the group). Fourty-eight hours after C. albicans inoculation; Group 1 received fluconazle (FLU)+OZO drops, Group 2 received FLU drop, Group 3 received OZO drop, Group 4 received FLU+ODW drops, Group 5 received ODW drop, Group 6 (infected control group) and Group 7 received PBS drop (negative control group). Treatment continued in all groups for 22 days for every 8 hours. Results Cornea cultures made 24 days post inoculation revealed statistically significant differences (p < 0,05) with concern to C. albicans amounts between Group 6 and Group 1–5. Statistical comparison of corneal opacity and corneal ulcer and conjunctivitis values among the Group 6 and Group 1–5 were also different significantly (p < 0,05) on days 20 and 24 post inoculation. Conclusion OZO and ODW were found to be effective in treating C. albicans keratitis in the present study. It has also been proven by this study that ODW contain 26 μg/ml was the most effective in the treatment of C. albicans keratitis.

New phenomena for clinicians, model of Candida albicans mobilization before and after biofilm formation in the intestinal mucosa of Wistar rats (Rattus norvegicus)

Background and Aim: The virulence and antifungal resistance of Candida albicans are recently known for their ability to form biofilm. This research aimed to construct an in vivo model of C. albicans biofilm in Wistar rats' intestinal mucosa and study their mobilization while in a planktonic and biofilm formation. In this study, there was one treatment group that was treated with three antibiotics, immunosuppressants, and C. albicans. Materials and Methods: This study was divided into control and treatment groups. The data sampling was conducted after C. albicans inoculation. The C. albicans biofilm formation stage was monitored with colony-forming units method calculation every week post-inoculation and then observed by the confocal laser scanning microscope. Results: The planktonic C. albicans overgrowth occurred up to 14 days after inoculation. The formation and maturation of C. albicans biofilm in the intestinal mucosa started in the 28th and 35th-day post-inoculation, respectively. The density of planktonic C. albicans in the stool was dramatically decreased on the 35th day. Before the biofilm formation, the planktonic Candida was carried away by food scraps to be released as a stool. However, there were minuscule or no planktonic Candida observed in the stool during and after biofilm formation. Instead, they were attached to the caecum's mucosa as a biofilm. Conclusion: We have proved that the planktonic C. albicans with its mobile nature were carried into the stool along with the rest of the feed, as we observed a lot of C. albicans cells found in the stool. Meanwhile, on day 28 after administration of antibiotics and immunosuppressants, no C. albicans was found in the stool samples, and at the same time, we observed C. albicans cells and their matrix attached to the intestinal mucosa as a biofilm.

Candida-Associated Denture Stomatitis and Murine Models: What Is the Importance and Scientific Evidence?

Considering the high prevalence and recurrence of Candida-associated denture stomatitis (CADS), in vivo studies in animal models are necessary before those in humans to evaluate new therapeutic strategies. This study aimed to review the literature on murine models of CADS induction using acrylic intraoral devices simulating dentures. Rats are recommended as experimental animals in these models as well as the adoption of a pasty diet. For maintenance in the proper position during the experiments, intraoral appliances must be obtained by individual impressions, using and retained exclusively by cementation on the molars. The region of interest for histopathological analysis was standardized as that corresponding to the area between the first molars. However, there is no consensus among the studies on the CADS induction rat models in relation to the Candida albicans inoculation and need for immunosuppression and/or administration of antibacterial drugs of animals. The greatest difficulty of the available models refers to maintaining the course of the lesion for a sufficient period to evaluate the effectiveness of the proposed treatment, considering the rapid and efficient murine immune response to candidal colonization. Therefore, future studies are necessary for the development of a robust and reproducible CADS model.

Biodistribution of free and encapsulated 99mTc-fluconazole in an infection model induced by Candida albicans

BackgroundCandida spp is an etiologic agent of fungal infections in hospitals and resistance to treatment with antifungals has been extensively reported. Thus, it is very important to develop formulations that increase effectiveness with low toxicity. In this sense, nanocarriers have been investigated, once they modify drug biodistribution profile. Thus, this study aimed to evaluate the biodistribution of free and encapsulated 99mTc-fluconazole into nanocapsules (NCs) in an experimental immunosuppressed murine model of Candida albicans infection. MethodsFluconazole was radiolabeled with technetium-99 metastable (99mTc) and encapsulated into conventional (99mTc-Fluconazole-PLA-POLOX) and surface-modified (99mTc-Fluconazole-PLA-PEG) NCs by the interfacial deposition of the preformed biodegradable polymer [poly (D,L-lactic acid) (PLA) and PLA–PEG (polyethyleneglycol)] followed by solvent evaporation. The size distribution and zeta potential of the NCs preparations were determined in a Zetasizer by photon correlation spectroscopy and laser Doppler anemometry, respectively. Free and encapsulated 99mTc-fluconazole were administered intravenously in immunosuppressed mice bearing a local infection induced by Candida Albicans inoculation in the right thigh muscle. At pre-established time intervals, tissues and organs of interest were removed and radioactivity was measured in an automatic gamma radiation counter. ResultsThe NCs diameter was between 200 and 400 nm with negative zeta potential values. Free 99mTc-fluconazole was more rapidly eliminated by the renal system compared to the encapsulated drug in NCs, which remained longer in blood circulation. The uptake of conventional NCs by mononuclear phagocyte system organs was higher than the one demonstrated by the surface-modified NCs. Both NCs remained longer in the infectious focus when compared to free 99mTc-fluconazole, but the results did not show a significant difference between NC formulations. ConclusionThese data indicate that these NCs might represent a therapeutic alternative for the treatment of candidiasis, once they remain more time in the infectious focus, allowing high retention of 99mTc-fluconazole at this site.

Induction of Severe Chronic Hyperplastic Candidiasis in Rat by Opportunistic Infection of C. albicans through Combination of Diabetes and Intermittent Prednisolone Administration

Chronic hyperplastic candidiasis progresses from squamous cell hyperplasia to squamous cell carcinoma (SCC); however, the oncogenic mechanism remains unclear. In the present study, we attempted to induce opportunistic Candida albicans infection and establish chronic hyperplastic candidiasis in rats by combining diabetic condition and prednisolone administration, followed by analysis of the inflammatory cells involved in the disease progression. Female Wistar Bunn/Kobori (WBN/Kob) rats were divided into 3 groups: alloxan-induced diabetic rats (A group) along with diabetic (AP group) and nondiabetic (P group) rats intermittently treated with prednisolone. Animals were euthanized at 42 weeks of age. Squamous cell hyperplasia following C. albicans infection in the forestomach was observed in almost all AP and A group rats. The lesions in the AP group were significantly more severe than those in the A group. In addition, SCC was detected in 1 AP group animal. Cluster of differentiation (CD)4-positive T cell and CD68-positive macrophage infiltration in the AP group was significantly stronger than that in the A group. These findings suggest that the combination of diabetes and intermittent prednisolone administration could induce chronic hyperplastic candidiasis without direct C. albicans inoculation and that CD4-positive T cells and CD68-positive macrophages may be highly involved in the pathogenesis of these hyperplastic lesions.

Chitinase 3-Like 1 Promotes Candida albicans Killing and Preserves Corneal Structure and Function by Controlling Host Antifungal Responses.

Chitinase 3-like 1 (CHI3L1) has been shown to play a role in promoting antibacterial responses, decreasing tissue injury, and enhancing pulmonary repair. This study sought to elucidate the role of CHI3L1 in augmenting the corneal innate immune response to Candida albicans infection in an animal model of fungal keratitis. Flagellin applied topically 24 h prior to C. albicans inoculation significantly protected the corneal from C. albicans and induced CHI3L1 expression in C57BL/6 mouse corneas. CHI3L1, however, played a detectable but minor role in flagellin-induced protection. While C. albicans keratitis was more severe in the corneas treated with Chi3l1 small interfering RNA (siRNA), corneas treated with recombinant CHI3L1 before C. albicans inoculation had markedly ameliorated keratitis, reduced fungal load, and decreased polymorphonucleocyte (PMN) infiltration in an interleukin 13 receptor α2 (IL-13Rα2)-dependent manner. CHI3L1 treatment resulted in the induction of the antimicrobial peptides β-defensin 3, CRAMP, and chemokine CXCL10 and its receptor CXCR3 in corneal epithelial cells. Importantly, CHI3L1 administered after C. albicans inoculation also had strong protection against fungal keratitis, suggesting a therapeutic window. This is the first report demonstrating that CHI3L1 is induced during fungal infection, where it acts as an immunomodulator to promote fungal clearance and to regulate antifungal innate immune responses in the cornea.

In Situ IgM Production and Clonal Expansion of B-1 Cells in Peritoneal Cavity Promote Elimination of C. albicans Infection in IgH Transgenic Mice with VH Derived from a Natural Antibody

B-1 cells are innate-like cells that play important roles in host defense against infection. However, the function of B-1 cells in fungi infection remains unclear. Previously we produced IgH transgenic mice TgVH3B4 with VH derived from a natural antibody 3B4 that can identify C. albicans, and found that TgVH3B4 mice were resistant to intraperitoneal (i. p.) and intravenous C. albicans infection. Most of the peritoneal cavity (PEC) B-1 cells in TgVH3B4 mice express transgenic BCR that binds C. albicans. In the present study, we explored the response of B-1 cells to C. albicans infection by applying i. p. inoculation of fungi in TgVH3B4 mice. We found that C. albicans was cleared more efficiently in TgVH3B4 mice after i. p. inoculation than that of littermate control. The level of C. albicans-reactive IgM in PEC of TgVH3B4 mice was much higher than that of control, and the number of B-1a B cells was also elevated in TgVH3B4 mice, which was mainly due to enhanced proliferation of B-1 cells. Additionally, numbers of C. albicans-specific B cells increased greatly in TgVH3B4 mice after C. albicans inoculation. Our data suggested that in situ IgM production and clonal expansion of B-1 cells in PEC participate in host defense against C. albicans infection.

Pathological analysis of the Candida albicans-infected tongue tissues of a murine oral candidiasis model in the early infection stage

ObjectiveThe early pathological process of Candida infection and immunological responses in tongues of the mice with experimental oral candidiasis was analysed. MethodsCD-1 mice, pretreated by prednisolone were orally inoculated with Candida albicans. Symptoms were monitored by measuring the area of white tongue coating and number of viable Candida cells in oral cavity. The histopathological analysis was carried by PAS-stain and immunofluorescent staining. IL-4, IL-12p70, IFN-γ, TNF-α in recovered from the homogenates of the tongues were measured by ELISA. ResultsThe fungus invaded the tongue surface of the mice and white patches developed within 24h after inoculation. Histopathological examination indicated the presence of local acute inflammation in superficial tissues of tongues covered by mycelium of C. albicans. Pathological exacerbation was observed from 24 to 48h after the inoculation and from then the symptoms of oral candidiasis appeared to move into the recovery phase. Inflammatory cells mainly consisting of neutrophils was accumulated and located under the lesions covered by Candida-hyphae. An increase in IL-12p70 and IFN-γ in tongue homogenates was observed at 48h after inoculation. ConclusionsThe worst condition in the pathological process in experimental oral candidiasis was found 48h after C. albicans inoculation. When the surface of the Candida-inoculated tongues was covered with Candida-hyphae, a dense accumulation of neutrophils was observed under the lesions and homogenates of the tongues contained increased levels of IL-12p70 and IFN-γ. These suggested that local pathological condition of Candida-infected tongues may be affected by neutrophils accumulation and increased levels of some cytokines.

CONSEQUENCES OF ORAL INFECTION WITH CANDIDA ALBICANS ON THE HISTOARCHITECTONICS OF ORGANS IN MALE RATS

Experiments were conducted to evaluate the immunosuppression’s effect on the development of oral candidiasis in Wistar rats. Animals were submitted to immunosuppression in order to facilitate the establishment and persistence of Candida albicans infection. Treatment with drugs (dexamethasone and tetracycline) was initiated 7 days before C. albicans inoculation and lasted until the end of the experiments, day 9 post-inoculation, but at a higher dose for dexamethasone and at a lower dose for tetracycline. The infection was done twice at a 24 hours difference. Establishment of C. albicans infection was done by oral inoculation with 0.1 ml of saline suspension containing 3.108 3,1 x 103 viable cells of C. albicans strain ATCC 10231. Tissue injury was determined by the hystological quantification of organs collected at days 3, 6 and respectively 9 of the experiment. Our results have shown that candidiasis affected organs in male rats in the following order: tongue, intestines, liver, spleen and kidney. There was a gradual evolution of the histological lesions severity in the tongue starting from the third day towards the end, but, in reverse, all the other organs affected started having regenerative healing processes at the end of the experiment.

Candida Albicans: The Estrogen Target for Vaginal Colonization

Estradiol (E(2)) stimulates colonization of the vagina by Candida albicans. Although this yeast expresses an estrogen-binding protein (EBP), the cellular target for estrogenic modulation of this infection is unresolved. Findings support direct E(2)-induced C. albicans growth as well as indirect effects via E(2)-induced changes in the vaginal epithelium. Our primary goal was to pursue the issue of direct versus indirect estrogen action on vaginal candidiasis using diethylstilbestrol (DES), an efficacious mammalian estrogen receptor agonist, which exhibits no detectable affinity for the EBP of C. albicans. We used both in vitro and in vivo experimentation with an EBP-positive strain of C. albicans isolated from the human vagina. Ligand-binding studies were performed with steroidal and nonsteroidal estrogens and anti-estrogens using the soluble EBP from both the yeast and the rat uterus. Mature ovariectomized rats were treated with either E(2) or DES for 7 days before and after C. albicans inoculation into the vaginas. Subsequent estrogen-sensitive colonization was quantified based on cultures of vaginal homogenates on Sabouraud dextrose (SD) agar pour plates. We confirmed that our isolate of C. albicans contained a high-affinity EBP, with no detectable affinity for DES. Vaginal colonization by C. albicans was 8.6-fold greater in response to in vivo treatment with E(2) than with the comparable dose regimen of DES. The mechanism for estrogen-sensitive vaginal colonization by C. albicans includes a functional ligand-EBP interaction within the yeast.

Effects of fluconazole on viable cell count in experimental intraperitoneal Candida abscesses.

We investigated the effects of fluconazole in experimental intraperitoneal Candida abscesses in neutropenic mice treated with cyclophosphamide to assess a clinically appropriate method for the application of fluconazole in fungal infections in patients with neutropenia. The efficacy of fluconazole in fungal infection was investigated in treatments started immediately after Candida albicans inoculation and before C. albicans inoculation (preventive use of fluconazole). In this intraabdominal fungal abscess model, it was confirmed that fungi in already formed abscess were not reduced in number by fluconazole, even when those fungi were susceptible to fluconazole. Fluconazole was effective with both administration methods. We conclude from this study that the effect of the preventive use of fluconazole was equivalent to the effect when treatment was started immediately after fungal inoculation.

Lighting conditions alter Candida albicans-induced sleep responses in rabbits.

To evaluate the influence of light on sleep patterns after microbial challenge, we studied rabbits housed in 12:12-h light-dark (LD), constant light (LL), or constant darkness (DD) before and after intravenous Candida albicans inoculation. Compared with the LD group, uninoculated LL rabbits sporadically increased slow-wave sleep and delta-wave amplitudes during the circadian period previously associated with the dark phase. In contrast, uninfected DD rabbits showed reduced sleep during the circadian period previously associated with the light phase. Inoculation of LD rabbits with Candida approximately 2 h after light onset increased slow-wave sleep and delta-wave amplitudes during hours 4-8 postinoculation and reduced these parameters during hours 20-46. In contrast, Candida-inoculated LL rabbits demonstrated increased slow-wave sleep for up to 28 h after inoculation, with little subsequent reduction; delta-wave amplitudes were similar to those of LD rabbits. Candida-inoculated DD rabbits demonstrated attenuated increases in slow-wave sleep and delta-wave amplitudes, but the suppression phase was not altered. We conclude that lighting conditions modulate microbially induced sleep alterations.

Efficacy of prophylactic and early fluconazole treatment on systemic candidiasis in experimentally neutropenic rabbits.

The efficacy of prophylactic and early fluconazole treatment on experimental systemic candidiasis was investigated in neuropenic rabbits. Fifteen rabbits were used and divided into three groups: fluconazole was started 24 h before the inoculation of Candida albicans in the first group, and 24 h after the inoculation in the second group. The third group was the control group without antifungal therapy. Prophylactic and early fluconazole treatment for 7 days after C. albicans inoculation did not reduce the mortality and tissue culture positivity in the rabbits significantly. Four of the five rabbits survived 7 days both in the prophylactic and early treatment groups. However, only one rabbit survived for 7 days in the control group. In diagnostic procedures, histopathological examination and evaluation with periodic acid-Schiff stain was found to be the most sensitive. In this study, prophylactic and early fluconazole treatment were found to be insufficient for treatment of systemic candidiasis in neutropenic rabbits.

Topical Ketoconazole for Experimental Candida Keratitis in Rabbits

Topical ketoconazole (2% ointment three times per day for three weeks) markedly reduced the severity of keratitis produced with Candida albicans inoculation in the right eyes of 20 rabbits. Clinical scores of affected eyes were significantly lower in the treated eyes than in the controls, which consisted of the 20 inoculated but untreated left eyes of the same rabbits. All cultures of corneal scrapings from the treated eyes were negative on the 12th day after inoculation, while two cultures were still positive at the end of the experiment (day 21) in the control eyes. Histopathologic examination showed less severe inflammatory changes in the treated eyes than in the control eyes.