Regulation of Candida albicans morphogenesis by tumor necrosis factor-alpha and potential for treatment of oral candidiasis

BACKGROUND: Endogenous tumor necrosis factor-alpha (TNF-alpha) has a beneficial effect as an activation mediator of host defense against infection by the fungus Candida albicans (C. albicans). However, it is unclear whether exogenous TNF-alpha has a beneficial or detrimental effect against Candida. MATERIALS AND METHODS: The direct effect of TNF-alpha on CO2-induced morphological transformation of C. albicans blastoconidia was examined in vitro and the effect of TNF-alpha was determined in a mouse model of oral candidiasis. RESULTS: TNF-alpha suppressed hyphal formation from C. albicans blastoconidia directly and dose-dependently, whereas it did not affect the fungal budding rate at concentrations ranging from 0.01 to 10 microg/ml. In vivo, the oral administration of TNF-alpha significantly reduced the C. albicans CFU in tongue tissues of treated mice. Histopathologically, there was a decrease in the number and size of C. albicans fungi in the tongue tissues. CONCLUSION: Since orally administered TNF-alpha suppressed fungal burden in the tongue tissue without significant detrimental effects, TNF-alpha has potential as a therapeutic agent against Candida.     

Histatin-derived peptides: potential agents to treat localised infections

Histatins are a family of histidine-rich, cationic peptides composed of up to 38 amino acids. They are secreted by the salivary glands of humans and some subhuman primates and are thought to be part of the host defence system in the oral cavity. Histatins exhibit in vitro activity against both bacteria and yeast, common to other antimicrobial peptides. Because of these activities, histatin-based peptides could play an important role in the treatment and prevention of infectious diseases. A 12 amino acid amidated fragment of histatin 5, designated P-113, has been identified as the smallest fragment that retains antimicrobial activity comparable to the parent compound. Animal studies and human clinical trials showed that P-113 has potential in preventing the development of gingivitis, with no adverse side effects. Histatin peptides also could be used for other therapeutic applications in which the infection is localised and accessible via topical delivery, such as treatment of candidiasis (thrush) and mucositis in the oral cavity, skin infections and treatment of lung infections afflicting cystic fibrosis patients.     

The essential oil of Melaleuca alternifolia (tea tree oil) and its main component, terpinen-4-ol protect mice from experimental oral candidiasis

The therapeutic efficacy of tea tree oil (TTO), Melaleuca alternifolia, and its main component, terpinen-4-ol, were evaluated in a murine oral candidiasis model. Prednisolone -pretreated mice were orally infected with a fluconazole-susceptible (TIMM 2640) or a resistant (TIMM 3163) strain of Candida albicans to induce oral candidiasis. TTO or terpinen-4-ol was administrated with a cotton swab 3 h and 24 h after candida infection. These treatments clearly showed a decrease in the symptom score of tongues and in the viable candida cell number in the oral cavity at 2 d after azole-susceptible C. albicans infection, although the degree of the efficacy was less than that of fluconazole. Even against oral candidiasis caused by azole-resistant C. albicans, TTO and terpinen-4-ol were similarly effective, while fluconazole appeared ineffective. These results suggest that TTO and terpinen-4-ol may have the potential of therapeutic ability for mucosal candidiasis which may also be applicable to C. albicans oral candidiasis induced by the azole-resistant strain.     

A study on the distribution of T-3262 (tosufloxacin tosilate) in salivary glands of rats using microautoradiography

The distribution of T-3262 (tosufloxacin tosilate) in salivary glands of rats was investigated with frozen-microautoradiography. One and 4 hours after oral administration of 14C-T-3262 at 100 mg/kg to rats submandibular glands, parotid glands and sublingual glands were removed, and a microautoradiogram of each was made. In the submandibular gland and the parotid gland 14C-T-3262 was distributed at high levels throughout the glands taken at 1 and 4 hours after administration, but lower levels than the other glands were found in the sublingual gland at 1 hour. The results of this study suggested that T-3262 penetrates effectively into the saliva, because 14C-T-3262 is distributed well into glandular acinus, striated duct and excretory duct. The microautoradiography was a useful and reliable method for investigating the distribution of antimicrobial agents in salivary glands.     

Oral candidiasis deteriorated by local application of a glucocorticoid-containing film in a mouse model

In order to estimate predisposing activity of oral application of beclomethasone dipropionate (BDP)-containing mucoadhesive films for oral candidiasis, the effects of BDP on growth of Candida albicans were examined in vivo and in vitro. Murine neutrophils inhibited the mycelial growth of C. albicans in vitro, but this anti-Candida activity was clearly suppressed by the presence of 10(-6) M of BDP. In vitro, a BDP-release test showed that the amount of BDP released from BDP-containing films into the fluid phase increased in a time- and concentration-dependent manner and reached about 10-15% of the total amount of BDP in the film within 30 min. When the BDP-containing film was attached to the tongues of mice orally infected with C. albicans, oral infection by C. albicans deteriorated, but not as severely as in mice systemically immunosuppressed with prednisolone. Based on these findings, we also discuss the problems associated with the clinical application of BDP-film as an anti-inflammatory tool.     

Antimicrobial activity of clove oil and its potential in the treatment of vaginal candidiasis

In the present study, we evaluated antimicrobial activity of clove oil against a range of fungal pathogens including that responsible for urogenital infection. Clove oil was found to possess strong antifungal activity against opportunistic fungal pathogens such as Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus, etc. The oil was found to be extremely successful in the treatment of experimental murine vaginitis in model animals. On evaluating various formulations, topical administration of the liposomized clove oil was found to be most effective against treatment of vaginal candidiasis.     

Antifungal activity of human salivary mucin‐derived peptide,MUC7 12‐mer,in a murine model of oral candidiasis

Abstract: Previous studies have shown that peptides derived from the N‐terminal region of the low molecular mass human salivary mucin, MUC7, possess potent in vitro cidal activity against Candida albicans and other medically important fungi. MUC7 12‐mer (residues 40–51 of the parent MUC7) peptide, having the optimal size and a net charge of +6, was found to be anticandidal in human saliva (clarified and unclarified), and its candidacidal potency was found to be superior to that of histatin 5 12‐mer (Hsn5 12‐mer). We have, therefore, explored the candidacidal potency of MUC7 12‐mer (l and d isomers) and Hsn5 12‐mer peptides in vivo. In vitro killing assay was performed to establish killing activity of the peptides against C. albicans prior to in vivo experiments. A murine model of oral candidiasis that has the characteristics of oral thrush in humans was employed for the in vivo studies, based on a previous protocol. Upon candidal induction, antifungal treatment application using agents emulsified in Pluronic F127 was performed for six consecutive days. Amphotericin B and clotrimazole emulsified in the same delivery system were used as positive control drugs. Candidacidal efficacy was evaluated microbiologically and histopathologically. Results demonstrated a considerable reduction of fungal burden by the MUC7 12‐mer peptides (l and d ), comparable to control drugs, and this effect was statistically significant, unlike the effect seen with Hsn5 12‐mer. Murine oral candidiasis model employed in this study is suitable to test the candidacidal agents employing Pluronic F127. In conclusion, MUC7 12‐mer appears to be a promising candidate as an antifungal agent for oral candidiasis.     

唾液sIgA对二相性白念珠菌粘附口腔颊粘膜细胞的影响

目的 研究唾液中sIgA对二相性白念珠菌粘附人口腔颊粘膜细胞的影响,探讨口腔念珠菌感染中唾液sIgA发挥的粘膜免疫作用。方法 用兔抗人sIgA血清中和人唾液中sIgA,^125I-sIgA放射免疫分析法检测唾液中sIgA的浓度,比较含sIgA及不含sIgA的唾液对二相性白念珠菌粘附人口腔颊粘膜细胞的影响。结果 含sIgA的唾液抑制孢子相及菌丝相白念珠菌粘附人口腔颊粘膜细胞的能力强于不含sIgA的唾液,且唾液中sIgA抑制孢子相白念珠菌粘附人口腔颊粘膜细胞的能力强于抑制菌丝相白念珠菌粘附人口腔颊粘膜细胞的能力。结论 唾液sIgA可抑制二相性白念珠菌对人口腔颊粘膜细胞的粘附,且更易抑制孢子相白念珠菌粘附人口腔颊粘膜细胞。     

Non-secretor status; a predisposing factor for vaginal candidiasis

A secretor is an individual who secretes blood group antigens into body fluids such as saliva, sweat, tears, semen and serum. An attempt has been made to establish the correlation between the secretor status and susceptibility to vaginal candidiasis. The secretor status was determined by haemagglutination inhibition technique. The presence of Candida albicans infection was detected by direct microscopy of the wet smear and confirmed by germ tube test and corn meal agar test. It was observed that out of the 64 patients, 15 were secretors and 49 were non-secretors. However 43 subjects were secretors and 13 non-secretors among the 56 controls. Thus prevalence of vaginal candidiasis was significantly higher in non-secretor group (P<0.01). The absence of blood group antigens in the body fluids and the lack of enzyme glycosyl transferase enhance the attachment of yeast to the epithelial cell and render the non-secretor more prone to infection.     

The therapeutic effects of itraconazole, a new triazole antifungal agent, for experimental fungal infections]

The therapeutic efficacy of itraconazole (ITZ), and oral triazole antifungal agent, was studied using several experimental fungal infections in animals. The following results were obtained: 1. ED50 values of ITZ and ketoconazole (KCZ) in a murine model of systemic candidiasis produced by intravenous challenge of Candida albicans alls were 32.9 mg/kg and 224 mg/kg, respectively. ITZ suppressed the proliferation of Candida experimentally colonized in the GI-tract of mice and/or a secondary dissemination induced by prednisolone. 2. An oral dose of 40 mg/kg/day ITZ administered for experimental pulmonary cryptococcosis in mice inhibited the fungal proliferation in the lung and the dissemination to the brain. 3. ED50 values of ITZ and KCZ for experimental systemic Aspergillus infection in mice were 103.6 mg/kg and 882 mg/kg, respectively. 4. ITZ suppressed the development of local symptoms in guinea pigs with experimental dermatophytosis. Culture studies performed on cutaneous tissues from infected sites on day-19 postinfection revealed that ITZ treatment lowered the culture-positive rate to a greater extent than KCZ-treatment. 5. Plasma concentrations of ITZ after a single dose of 100 mg/kg in mice were determined using the bioassay method: Cmax was 11 micrograms/ml and T 1/2 was 24 hours. 6. These results show that oral ITZ is highly effective in the treatment of deep-seated and superficial fungal infections produced in experimental animals.     

Lipopolysaccharide-induced subsensitivity of protease-activated receptor-2 in the mouse salivary glands in vivo

Protease-activated receptor-2 (PAR-2) acts as a modulator of multiple physiological/pathophysiological functions including salivary exocrine secretion. Given the supersensitivity of endothelial PAR-2 under endotoxaemia, we investigated if endotoxin/lipopolysaccharide (LPS) could alter the sensitivity of PAR-2 in the salivary glands. The in vivo salivation in response to i.v. administration of the PAR-2-activating peptide SLIGRL-NH2, but not of carbachol, gradually decreased 6-20 h after LPS administration in the mice. The LPS-induced hyporeactivity to the PAR-2 agonist was partially reversed by repeated administration of aprotinin, a non-specific protease inhibitor. PAR-2 mRNA levels in the salivary glands, as assessed by the semi-quantitative RT-PCR analysis, remained unchanged following LPS challenge. Our findings indicate that in contrast to the supersensitivity of endothelial PAR-2 as described previously, subsensitivity of PAR-2 in the salivary glands develops during the LPS-induced systemic inflammation, which might involve desensitisation of PAR-2 by endogenous proteases.     

Prophylactic role of immunomodulators in treatment of systemic candidiasis in leukopenic mice

In the present study, we have evaluated prophylactic role of various immunomodulators viz. lipopolysachharide, protein A and tuftsin to impart protection against experimental candidiasis in leukopenic mice. Both free as well as liposomised form of nystatin was not effective enough in offering complete cure against less susceptible isolate of Candida albicans (JNMCR) infection in immunodebilitant mice. Interestingly, the pretreatment of leukopenic mice with immunomodulators before challenging them with C. albicans increased therapeutic efficacy of the nystatin against systemic candidiasis. Efficacy of the treatment was evaluated on the basis of survival of the animals as well as fungal load in systemic circulation and various organs viz. liver, kidney, spleen and lungs of the treated animals.     

Botulinum Toxin A for Oral Cavity Cancer Patients: In Microsurgical Patients BTX Injections in Major Salivary Glands Temporarily Reduce Salivary Production and the Risk of Local Complications Related to Saliva Stagnation

In patients suffering from oral cavity cancer surgical treatment is complex because it is necessary to remove carcinoma and lymph node metastasis (through a radical unilateral or bilateral neck dissection) and to reconstruct the affected area by means of free flaps. The saliva stagnation in the post-operative period is a risk factor with regard to local complications. Minor complications related to saliva stagnation (such as tissue maceration and wound dehiscence) could become major complications compromising the surgery or the reconstructive outcome. In fact the formation of oro-cutaneous fistula may cause infection, failure of the free flap, or the patient’s death with carotid blow-out syndrome. Botulinum injections in the major salivary glands, four days before surgery, temporarily reduces salivation during the healing stage and thus could reduce the incidence of saliva-related complications. Forty three patients with oral cancer were treated with botulinum toxin A. The saliva quantitative measurement and the sialoscintigraphy were performed before and after infiltrations of botulinum toxin in the major salivary glands. In all cases there was a considerable, but temporary, reduction of salivary secretion. A lower rate of local complications was observed in the post-operative period. The salivary production returned to normal within two months, with minimal side effects and discomfort for the patients. The temporary inhibition of salivary secretion in the post-operative period could enable a reduction in saliva-related local complications, in the incidence of oro-cutaneous fistulas, and improve the outcome of the surgery as well as the quality of residual life in these patients.     

The effect of amoxycillin on salivary nitrite concentrations: an important mechanism of adverse reactions?

Broad spectrum antibiotics are known to predispose towards oral candidiasis and gastroenteritis. Oral nitrite synthesis by commensal bacteria may be important in protecting the mouth and lower intestine from pathogenic organisms, including Candida albicans. The effect of 2 days administration of the broad spectrum antibiotic amoxycillin on salivary nitrite concentration, following a 200 mg potassium nitrate oral load, was studied in 10 healthy volunteers. The Cmax fell by 40% and the AUC was reduced by 1227 microM h (43%, 95% CI 273, 2181, P < 0.006) in the antibiotic treated group when compared with control. These findings suggest that destruction of nitrate reductase containing bacteria in the mouth by antibiotics may explain an increased incidence of infection with Candida and other pathogens.     

Histatins: antimicrobial peptides with therapeutic potential

Histatins are a group of antimicrobial peptides, found in the saliva of man and some higher primates, which possess antifungal properties. Histatins bind to a receptor on the fungal cell membrane and enter the cytoplasm where they target the mitochondrion. They induce the non-lytic loss of ATP from actively respiring cells, which can induce cell death. In addition, they have been shown to disrupt the cell cycle and lead to the generation of reactive oxygen species. Their mode of action is distinct from those exhibited by the conventional azole and polyene drugs, hence histatins may have applications in controlling drug-resistant fungal infections. The possibility of utilising histatins for the control of fungal infections of the oral cavity is being actively pursued with the antifungal properties of topical histatin preparations and histatin-impregnated denture acrylic being evaluated. Initial clinical studies are encouraging, having demonstrated the safety and efficacy of histatin preparations in blocking the adherence of the yeast Candida albicans to denture acrylic, retarding plaque formation and reducing the severity of gingivitis. Histatins may represent a new generation of antimicrobial compounds for the treatment of oral fungal infections and have the advantage, compared with conventional antifungal agents, of being a normal component of human saliva with no apparent adverse effects on host tissues and having a mode of action distinct to azole and polyene antifungals.     

Artemisia princeps Pamp. Essential oil and its constituents eucalyptol and α-terpineol ameliorate bacterial vaginosis and vulvovaginal candidiasis in mice by inhibiting bacterial growth and NF-κB activation

To investigate the inhibitory effects of Artemisia princeps Pamp. (family Asteraceae) essential oil (APEO) and its main constituents against bacterial vaginosis and vulvovaginal candidiasis, their antimicrobial activities against Gardnerella vaginalis and Candida albicans in vitro and their anti-inflammatory effects against G. vaginalis-induced vaginosis and vulvovaginal candidiasis were examined in mice. APEO and its constituents eucalyptol and α-terpineol were found to inhibit microbe growths. α-Terpineol most potently inhibited the growths of G. vaginalis and C. albicans with MIC values of 0.06 and 0.125?% (v/v), respectively. The antimicrobial activity of α-terpineol was found to be comparable to that of clotrimazole. Intravaginal treatment with APEO, eucalyptol, or α-terpineol significantly decreased viable G. vaginalis and C. albicans numbers in the vaginal cavity and myeloperoxidase activity in mouse vaginal tissues compared with controls. These agents also inhibited the expressions of proinflammatory cytokines (IL-1 β, IL-6, TNF- α), COX-2, iNOS, and the activation of NF- κB and increased expression of the anti-inflammatory cytokine IL-10. In addition, they inhibited the expressions of proinflammatory cytokines and the activation of NF- κB in lipopolysaccharide-stimulated peritoneal macrophages, and α-terpineol most potently inhibited the expressions of proinflammatory cytokines and NF- κB activation. Based on these findings, APEO and its constituents, particularly α-terpineol, ameliorate bacterial vaginosis and vulvovaginal candidiasis by inhibiting the growths of vaginal pathogens and the activation of NF- κB.     

Secretion of IgA by rat parotid and submandibular cells in response to autonomimetic stimulation in vitro

The major antibody in saliva is IgA, which is actively transported by pIgR expressed by parenchymal cells within the salivary glands. The rate of IgA secretion into saliva is regulated by the autonomic nerves supplying the glands in vivo. This study examined the mechanism of increased IgA secretion into saliva with autonomimetic stimulation. In vitro stimulation of IgA secretion from cells prepared by digestion of rat salivary glands found submandibular cell preparations responded to alpha- and beta-adrenergic stimuli whereas the parotid cells responded only to beta-adrenergic stimulation, although cells from both glands responded similarly to cholinergic stimulation. The additional responsiveness of submandibular cells to alpha-adrenergic stimulation probably reflects the presence of granular duct cells (absent in parotid glands) which are known to secrete protein in response to high frequency sympathetic stimulation. The increased secretion of IgA was not dependant upon increased plasma cell activation since isolated salivary gland plasma cells did not respond to agonists. Further evidence for the regulating role of parenchymal cells in IgA secretion into saliva was revealed by analysis of polymeric immunoglobulin receptor (pIgR) levels expressed on cells. Following in vivo nerve stimulation, there was an increased amount of pIgR expressed on the membrane surface. This was functionally demonstrated in vitro by increased uptake of human IgA by acutely prepared rat salivary cells following stimulation by adrenaline, indicating increased mobilisation of pIgR with stimulation. This study confirms that salivary cells increase the delivery of IgA into saliva by a pIgR-mediated mechanism in response to autonomic stimulation.     

Leucinostatin-A loaded nanospheres: characterization and in vivo toxicity and efficacy evaluation

Leucinostatin A (Leu-A) is a nonapeptide exerting a remarkable activity especially against Candida albicans and Cryptococcus neoformans; nevertheless, its employment is limited due its toxicity. Therefore, we recently developed liposomal formulations, as suitable delivery systems, in order to increase its therapeutic index. However, liposomes present disadvantages related to their long-term instability. For this reason poly(lactic-co-glycolic) nanospheres (NS) were chosen as alternative colloidal carriers for Leu-A delivery. NS were formulated by spontaneous emulsification solvent diffusion method. This study investigates the effects of different parameters on drug encapsulation efficiency and particle size as well. The best preparation obtained was also characterized for its in vitro release, in vivo acute toxicity (LD50), and effectiveness against C. albicans in mice. In vitro release was performed over 100 h and resulted sufficiently sustained with more than 93% of the peptide released. Acute toxicity showed that the LD50 was increased more than 18-fold and the study on systemic candidiasis models revealed high effectiveness of the NS in reducing either the growth of fungal colonies in infected mice liver or in the mortality index. In conclusion, we can propose that Leu-A loaded NS could represent a new promising therapeutic system against Candida infection.     

Immunomodulation by the new synthetic thiazole derivative tiprotimod. 3rd communication: influence on host resistance to microorganisms, tumors and on experimental immune disorders

To evaluate the influence of [2-(3-carboxy-1-probylthio)-4-methyl-1,3-thiazole]acetic acid (tiprotimod, HBW 538) on the host defense mechanisms, a number of experimental studies in different animal models were performed. The prophylactic treatment of NMRI mice with tiprotimod significantly prolonged the mean survival time of the animals after intravenous infection with Candida albicans 200/175 and increased the resistance to the fungal infection to 180% in comparison to controls. In vitro the drug showed no direct fungistatic or fungicidal activity. In an experimental model of persistent systemic candidiasis Balb/c mice infected intravenously with Candida albicans were treated with the immunomodulator tiprotimod after the fungal colonization of kidney was manifested (3 days post infection). The treatment of the mice after the infection resulted in a reduction of the infectious load and the abscess formation in kidney as well as in a decrease of numbers of yeasts in the urine. In the syngeneic B16 melanoma tumor model tiprotimod significantly prolonged the medium survival time and reduced the number of visuable metastases in the lungs even when applied after resection of the primary tumor graft. Tiprotimod also beneficially influenced the course of the disease in two murine graft-vs-host models (hemolytic anemia and immune complex glomerulonephritis) which lead to a B cell mediated autoimmune disease with fatal outcome. The application of the drug in the induction phase mitigated the development of the diseases and prevented animals from dying.(ABSTRACT TRUNCATED AT 250 WORDS)