Losartan Plays a Fungistatic and Fungicidal Activity Against Candida albicans Biofilms: Drug Repurposing for Localized Candidosis

Candidosis is one of the most frequent opportunistic infections and exhibits variable clinical presentations, including oral localized forms. Drugs affecting the renin-angiotensin system targets inhibit secreted aspartic proteases from Candida albicans. The objective of the study was to evaluate whether losartan has antimicrobial action against C. albicans biofilms. Biofilms were treated with losartan or aliskiren (for comparison) for 24 h. Metabolic activity of viable cells and growth inhibition of C. albicans biofilms were assessed using XTT [2,3-Bis(2-Methoxy-4-Nitro-5-Sulfophenyl)-5-[(Phenyl-Amino)Carbonyl]-2H-Tetrazolium Hydroxide] and colony-forming unit assays, respectively. In addition, the cytotoxicity of the drugs on human cells was evaluated using the AlamarBlue assay. Both drugs decreased fungal viability at all concentrations. In addition, all concentrations of losartan inhibited the growth of C. albicans biofilm, ranging from 47% to 88.5%, whereas aliskiren showed inhibition from 1 to 10 mg/mL, which ranged from 16% to 97.6%. Furthermore, at certain concentrations, these drugs maintained the viability of human cells. Losartan and aliskiren have fungistatic and fungicidal action against C. albicans biofilms and are compatible with human cells. Therefore, these antihypertensive drugs can be repurposed to interfere with the metabolism and development of Candida biofilms, which are widely associated with clinical forms of candidosis, including oral localized forms such as denture stomatitis.

Antimicrobial potential of plant extracts from the Brazilian Cerrado

Abstract Bacteria are related do different oral diseases, such as dental caries and periodontal disease. Therefore, the control or/and eradication of microorganisms and their by-products is primordial for the success of their treatment. An alternative for decrease bacterial load is the use of plant extracts used in popular medicine. The cytotoxicity and antimicrobial action of extracts of Cariniana rubra Gardiner ex Miers, Senna martiniana, Anadenanthera colubrina (Vell.) Brenan and Spiranthera odoratissima St. Hil. against strains of Streptococcus mutans, Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Aggregatibacter actinomyces- tencomitans and Candida albicans were investigated. Cytotoxicity was assessed at concentrations of 1, 10, 40, 80, 100 and 1000 μg/mL by means of the MTT test and compared to a control group with untreated cells. Those with acceptable cytotoxicity had the antimicrobial action measured by the XTT test. As a positive control, sodium hypochlorite was used. Cariniana rubra Gardiner ex Miers had the highest citototoxicity results while Spiranthera odoratissima St. Hil. had the best results, but all extracts showed acceptable cytotoxicity at different concentrations. The plant extracts showed higher activity against A. actinomycetencomitans: Anadenanthera columbrina (Vell.) Brenan (80.52%) at 40 μg/mL, Spiranthera odoratissima St. Hil (78.48%) in 1 μg/mL, Senna martiniana (73.28%) in the concentration of 40 μg/mL and Cariniana rubra Gardiner ex Miers (70.50%) in 10 μg/mL. All extracts analyzed showed acceptable cytotoxicity at different concentrations and were promising for inhibition of the pathogenic microorganisms studied.

Profile of host cell responses to exposure to stressed bacteria in planktonic; dislodged, and intact biofilm mode

The host defense response to microbial challenge emerging from the root canal system leads to apical periodontitis. The aim of this study was to evaluate the expression of inflammatory cytokines and Nitric Oxide (NO) by macrophages after interaction with Enterococcus faecalis in the: plankton and dislodged biofilm mode; intact biofilm mode stimulated by calcium hydroxide (CH), CH and chlorhexidine (CHX) or Triple Antibiotic Paste (TAP). For this purpose, culture of macrophages from monocytes in human peripheral blood (N=8) were exposed to the different modes of bacteria for 24 hours. Subsequently, the cytokines, such as, Tumor Necrotic Factor- alfa (TNF-α), interleukin (IL)-1β, IL-6, IL-10; and NO were quantified by Luminex xMAP and Greiss reaction, respectively. In addition to the potential therapeutic effects of the intracanal medication, their antimicrobial activity against Enterococcus faecalis biofilm were also tested in vitro by confocal microscopy. The experiments` data were analyzed by the Kruskal-Wallis test with the Dunn post hoc test (α < 0.05). Bacteria in dislodged biofilm mode were shown to be more aggressive to the immune system than bacteria in plankton mode and negative control, inducing greater expression of NO and TNF-α. Relative to bacteria in intact biofilm mode, the weakest antimicrobial activity occurred in Group CH. In Groups CH/CHX and TAP the percentage of dead bacteria was significantly increased to the same extent. Interestingly, the biofilm itself did not induce the release of pro-inflammatory cytokines - except for NO - while the biofilm treated with TAP and CH based pastes enhanced the levels of IL-6 and TNF-α; and IL-1 β, respectively. In contrast, the levels of a potent anti-inflammatory (IL-10) were increased in Group TAP.

Antifungal activity of Punicalagin-nystatin combinations against Candida albicans

OBJECTIVES

Oral candidiasis is the most common opportunistic fungal infection of oral mucosa and results from an overgrowth of Candida, especially Candida albicans. The potential anti-C. albicans and cytotoxicity of punicalagin (PCG), isolated from Punica granatum, alone or with nystatin (NYS) were evaluated.

METHODS

Activity of compounds alone or in combinations was determined against two C. albicans strains (ATCC 90028 and SC5314). Minimal inhibitory concentration (MIC)-50 and Minimum Fungicidal Concentration (MFC) were assessed by XTT assay and CFU counts, respectively. For combinations, determination of fractional inhibitory concentration index was performed. Ergosterol pathway was investigated as a possible PCG antifungal mechanism. Cytotoxicity assays were undertaken on human primary oral keratinocytes and gingival fibroblasts incubated with antifungal concentrations of PCG and/or NYS for 24 hr.

RESULTS

Combination of NYS and PCG increased antifungal efficacy, compared with compounds tested alone. Combinations 4 (PCG-6.25 μg/ml; NYS-3.9 μg/ml) and 5 (PCG-12.5 μg/ml; NYS-1.95 μg/ml) were more effective since they reduced the MIC-50 of PCG (50 μg/ml) by 8 and 4 times, respectively, increased the candidal inhibition and nullified the PCG cytotoxicity for keratinocytes. PCG antifungal mechanism did not involve ergosterol biosynthesis pathway.

CONCLUSIONS

The favorable outcomes for combination of PCG and NYS encourage further testing this therapeutic strategy against C. albicans.

What is the response profile of deciduous pulp fibroblasts stimulated with E. coli LPS and E. faecalis LTA?

Background

Oral fibroblast immunological responses to bacterial stimuli are well known. However, there are few studies about pulp fibroblasts from deciduous teeth (HDPF) responses, which are important for the treatment of pulp infections in children. The aim of this study was to evaluate expression and production of inflammatory cytokines and chemokines by HDPF when challenged with bacterial antigens normally present in advanced caries lesions.

Methods

Triplicate HDPF from 4 children (n = 4; 2 boys and 2 girls) were cultured by explant technique and challenged or not with Escherichia coli lipopolysaccharide/1 μg/mL (EcLPS) or Enterococcus faecalis lipoteichoic acid/1 μg/mL (EfLTA) for 6 and 24 h. Most of published studies employed immortalized cells, i.e., without checking possible gender and genetic variables. mRNA expression and protein production were evaluated by RT-qPCR and ELISA MILLIPLEX®, respectively, for Interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-17, Chemokine C-C motif ligand 2/monocyte chemoattractant protein 1 (CCL2/MCP-1), Chemokine C-C motif ligand 3/macrophage inflammatory protein 1-alpha (CCL3/MIP1-α), Chemokine C-C motif ligand 5/ regulated on activation, normal T cell expressed and secreted (CCL5/RANTES), C-X-C motif chemokine 12/ stromal cell-derived factor 1 (CXCL12/SDF-1), Tumor Necrosis Factor-alpha (TNF-α), Interferon-gamma (IFN γ), Vascular Endothelial Growth Factor (VEGF), Colony stimulating factor 1 (CSF-1) and Macrophage colony-stimulating factor (M-CSF).

Results

EcLPS increased IL-1α, IL-1β, IL-8, CCL2, CCL5, TNF-α and CSF-1 mRNA and protein levels while EfLTA was only able to positively regulate gene expression and protein production of IL-8.

Conclusion

The results of the present study confirmed our hypothesis, since pulp fibroblasts from deciduous teeth are capable of increasing gene expression and protein production after being stimulated with EcLPS and EfLTA.

Candida albicans-Cell Interactions Activate Innate Immune Defense in Human Palate Epithelial Primary Cells via Nitric Oxide (NO) and β-Defensin 2 (hBD-2)

The presence of Candida albicans in the biofilm underlying the dental prosthesis is related to denture stomatitis (DS), an inflammatory reaction of the oral mucosa. The oral epithelium, a component of the innate immune response, has the ability to react to fungal invasion. In this study, we evaluated the in vitro effect of viable C. albicans on the apoptosis, nitric oxide (NO) production, and β-defensin 2 (hBD-2) expression and production of human palate epithelial cells (HPECs). We further determined whether or not these effects were correlated with fungal invasion of epithelial cells. Interaction between HPEC primary culture and C. albicans was obtained through either direct or indirect cell–cell contact with a supernatant from a hyphal fungus. We found that the hyphae supernatants were sufficient to induce slight HPEC apoptosis, which occurred prior to the activation of the specific mechanisms of epithelial defense. The epithelial defense responses were found to occur via NO and antimicrobial peptide hBD-2 production only during direct contact between C. albicans and HPECs and coincided with the fungus’s intraepithelial invasion. However, although the hBD-2 levels remained constant in the HPEC supernatants over time, the NO release and hBD-2 gene expression were reduced at a later time (10 h), indicating that the epithelial defense capacity against the fungal invasion was not maintained in later phases. This aspect of the immune response was associated with increased epithelial invasion and apoptosis maintenance.

Antimicrobial activity of denture adhesive associated with Equisetum giganteum- and Punica granatum-enriched fractions against Candida albicans biofilms on acrylic resin surfaces

Candida biofilms adhere to the internal surface of removable dentures, which is an etiological factor in the pathogenesis of denture stomatitis (DS). Adhesive materials are used at the base of maxillary complete dentures to improve their retention and chewing qualities. This article reports the antimicrobial activity of the enriched fractions of Equisetum giganteum and Punica granatum incorporated into a denture adhesive against C. albicans biofilm. The biofilms were induced on the surface of heat-cured acrylic resin specimens that were previously treated with a mixture of adhesive/herb extracts. The antimicrobial activity was evaluated by CFU counts, XTT reduction, and SEM and CLSM analysis. Both herb extracts amplified the anti-biofilm action of the adhesive on the acrylic resin by up to 12 h. Therefore, when these extracts were combined with COREGA®, they played a collaborative and innovative role in biofilm control and can be considered alternatives for temporary use in the treatment and/or prevention of DS.

Equisetum giganteum influences the ability of Candida albicans in forming biofilms over the denture acrylic resin surface

CONTEXT

Equisetum giganteum L. (Equisetaceae) is an endemic plant of Central and South America used in traditional medicine. Natural drugs have been frequently used in the treatment of a myriad of diseases, proving to be an alternative to synthetic chemicals, and have been intensively studied in the prevention of sicknesses, including oral diseases.

OBJECTIVE

This study evaluated the in vitro antiadherent activity of E. giganteum extract against Candida albicans biofilms.

MATERIALS AND METHODS

Crystal violet and colony-forming units assays were used to quantify the total biofilm biomass and biofilm living cells on a denture base acrylic resin pretreated with hydroethanolic extract of E. giganteum in different concentrations (50, 25, 16, 8, and 4 mg/mL), after 24 h of biofilm development.

RESULTS

Equisetum giganteum affected biofilms by reduction of biomass and living cells per area of acrylic specimens. The results revealed reduction of 15-44% of the biofilm mass and reduction of numbers of colony-forming units (CFUs) present in biofilms (79%) compared to the untreated control (CTRL/PBS). At all concentrations, it demonstrated important antiadherent activity on Candida albicans biofilms, the main microbe in denture stomatitis.

DISCUSSION AND CONCLUSION

The present findings show that E. giganteum antimicrobial effects may qualify the extract as a promising natural alternative for topical treatment or prevention of denture stomatitis. The usage of drugs made of natural products shows advantages in relation to synthetic drugs on the market, such as lower cost, lower toxicity, and in relation to the occurrence of microbial resistance.