Photodynamic inactivation in the expression of the Candida albicans genes ALS3, HWP1, BCR1, TEC1, CPH1, and EFG1 in biofilms

Assessing the efficacy of gutiferone E in photodynamic therapy for oral candidiasis

The rise in antifungal resistance and side effects of conventional treatments drive the search for innovative therapies like Photodynamic Therapy (PDT). This study explored the efficacy of PDT mediated by gutiferone, an isolated compound from red propolis, for candidiasis treatment. Multiple evaluation methods were employed, including determining the minimum inhibitory concentration (MIC) via broth microdilution, quantifying biomass using crystal violet detachment, and cell counting through total plate count. PDT mediated by gutiferone was also assessed in five groups of mice, followed by histopathological examination and agar plating of lingual tissue samples. Among the seven Candida species tested, gutiferone displayed efficacy against C. albicans, C. glabrata, and C. tropicalis, with MIC values of 1000 μg/mL. In C. tropicalis biofilms, exposure to gutiferone led to a reduction of 1.61 Log10 CFU/mL. PDT mediated by gutiferone achieved an average reduction of 3.68 Log10 CFU/mL in C. tropicalis biofilm cells, underscoring its potent fungicidal activity. Histopathological analysis revealed fungal structures, such as pseudohyphae and hyphae, in infected groups (G2) and irradiated mice. In contrast, groups treated with gutiferone or subjected to gutiferone-assisted PDT (G5) exhibited only few blastoconidia. Furthermore, CFU/mL assessments in lingual tissue post-treatment demonstrated a significantly lower count (0.30 Log10 CFU/mL) in the G5 group compared to G2 (2.43 Log10 CFU/mL). These findings highlight the potential of PDT mediated by gutiferone as a promising alternative for managing denture stomatitis. Future research and clinical investigations offer the promise of validating its clinical applicability and improving outcomes in the treatment of oral candidiasis.

RNA-Seq-Based Transcriptomics and GC-MS Quantitative Analysis Reveal Antifungal Mechanisms of Essential Oil of Clausena lansium (Lour.) Skeels Seeds against Candida albicans

Infections caused by Candida albicans (C. albicans) and increasing resistance to commonly used drugs lead to a variety of mucosal diseases and systemic infectious diseases. We previously confirmed that the essential oil of Clausena lansium (Lour.) Skeels seeds (CSEO) had antifungal activity against C. albicans, but the detailed mechanism between the chemical components and antifungal activity is unclear. In this study, a quantitative analysis of five volatile components of CSEO, including sabinene, α-phellandrene, β-phellandrene, 4-terpineol, and β-caryophyllene, was carried out using the gas chromatography-mass spectrometry (GC-MS) method. Both the broth dilution and kinetic growth methods proved that the antifungal activity of CSEO against fluconazole-resistant C. albicans was better than that of its main components (sabinene and 4-terpineol). To further investigate the inhibitory mechanism, the transcriptional responses of C. albicans to CSEO, sabinene, and 4-terpineol treatment were determined based on RNA-seq. The Venn diagram and clustering analysis pattern of differential expression genes showed the mechanism of CSEO and 4-terpineol's anti-C. albicans activity might be similar from the perspective of the genes. Functional enrichment analysis suggested that CSEO regulated adherence-, hyphae-, and biofilm-formation-related genes, which may be CSEO's active mechanism of inhibiting the growth of fluconazole-resistant C. albicans. Overall, we preliminarily revealed the molecular mechanism between the chemical components and the antifungal activity of CSEO against C. albicans. This study provides new insights to overcome the azole resistance of C. albicans and promote the development and application of C. lansium (Lour.) Skeels seeds.

Hyphae-specific genes: Possible molecular targets for magnetic iron oxide nanoparticles alone and combined with visible light in Candida albicans

Candida albicans readily develops resistance to fluconazole. Magnetic iron oxide nanoparticles (denoted as MION) and antimicrobial photodynamic therapy are attracting attention as therapeutic agents. This study aims to investigate the inhibitory efficacy of MION alone and combined with visible light against C. albicans and expression analysis of hyphal wall protein 1 (HWP1) and agglutinin-like sequence 1 (ALS1) genes in C. albicans. Antifungal susceptibility testing, photodynamic activity assay, reactive oxygen species (ROS) production assay and gene expression analysis were determined in C. albicans treated with MION alone and combined with visible light. MION at 1 × minimum inhibitory concentration (MIC) level (500 μg/mL) exhibited antifungal activity against C. albicans isolates. Further, 1 × MIC levels of MION alone and combined with visible light displayed remarkable fungicidal effects at 24 and 48 h after treatment. The MION combined with visible light caused the highest levels of ROS production by all C. albicans isolates. The relative RT-PCR data showed significant downregulation of HWP1 and ALS1 genes which are the key virulence genes in C. albicans. Differences in gene expression of  HWP1 and ALS1 were more significant in MION combined with visible light treatments than MION alone. Our study sheds a novel light on facile development of effective treatment of C. albicans especially fluconazole-resistant C. albicans infections. The hyphae-specific genes HWP1 and ALS1 could be probable molecular targets for MION alone and combined with visible light in C. albicans.

New Insights in Phenothiazinium-Mediated Photodynamic Inactivation of Candida Auris

In recent years, Candida auris has emerged as a hazardous hospital-acquired pathogen. Its resistance to antifungal treatments makes it challenging, requiring new approaches to manage it effectively. Herein, we aimed to assess the impact of photodynamic inactivation mediated by methylene blue (MB-PDI) or 1,9-dimethyl MB (DMMB-PDI) combined with a red LED against C. auris. To evaluate the photoinactivation of yeasts, we quantified colony-forming units and monitored ROS production. To gain some insights into the differences between MB and DMMB, we assessed lipid peroxidation (LPO) and mitochondrial membrane potential (ΔΨm). After, we verified the effectiveness of DMMB against biofilms by measuring metabolic activity and biomass, and the structures were analyzed through scanning electron microscopy and optical coherence tomography. We also evaluated the cytotoxicity in mammalian cells. DMMB-PDI successfully eradicated C. auris yeasts at 3 μM regardless of the light dose. In contrast, MB (100 μM) killed cells only when exposed to the highest dose of light. DMMB-PDI promoted higher ROS, LPO and ΔΨm levels than those of MB. Furthermore, DMMB-PDI was able to inhibit biofilm formation and destroy mature biofilms, with no observed toxicity in fibroblasts. We conclude that DMMB-PDI holds great potential to combat the global threat posed by C. auris.

New Applications of Photodynamic Therapy in the Management of Candidiasis

The most important aetiological agent of opportunistic mycoses worldwide is Candida spp. These yeasts can cause severe infections in the host, which may be fatal. Isolates of Candida albicans occur with greater frequency and variable resistance patterns. Photodynamic therapy (PDT) has been recognised as an alternative treatment to kill pathogenic microorganisms. PDT utilises a photosensitizer, which is activated at a specific wavelength and oxygen concentration. Their reaction yields reactive oxygen species that kill the infectious microorganism. A systematic review of new applications of PDT in the management of candidiasis was performed. Of the 222 studies selected for in-depth screening, 84 were included in this study. All the studies reported the antifungal effectiveness, toxicity and dosimetry of treatment with antimicrobial PDT (aPDT) with different photosensitizers against Candida spp. The manuscripts that are discussed reveal the breadth of the new applications of aPDT against Candida spp., which are resistant to common antifungals. aPDT has superior performance compared to conventional antifungal therapies. With further studies, aPDT should prove valuable in daily clinical practice.

Photosensitizers Mediated Photodynamic Inactivation against Fungi

Superficial and systemic fungal infections are essential problems for the modern health care system. One of the challenges is the growing resistance of fungi to classic antifungals and the constantly increasing cost of therapy. These factors force the scientific world to intensify the search for alternative and more effective methods of treatment. This paper presents an overview of new fungal inactivation methods using Photodynamic Antimicrobial Chemotherapy (PACT). The results of research on compounds from the groups of phenothiazines, xanthanes, porphyrins, chlorins, porphyrazines, and phthalocyanines are presented. An intensive search for a photosensitizer with excellent properties is currently underway. The formulation based on the existing ones is also developed by combining them with nanoparticles and common antifungal therapy. Numerous studies indicate that fungi do not form any specific defense mechanism against PACT, which deems it a promising therapeutic alternative.

Pathogenesis and Clinical Relevance of Candida Biofilms in Vulvovaginal Candidiasis

The ability of Candida spp. to form biofilms is crucial for its pathogenicity, and thus, it should be considered an important virulence factor in vulvovaginal candidiasis (VVC) and recurrent VVC (RVVC). Its ability to generate biofilms is multifactorial and is generally believed to depend on the site of infection, species and strain involved, and the microenvironment in which the infection develops. Therefore, both cell surface proteins, such as Hwp1, Als1, and Als2, and the cell wall-related protein, Sun41, play a critical role in the adhesion and virulence of the biofilm. Immunological and pharmacological approaches have identified the NLRP3 inflammasome as a crucial molecular factor contributing to host immunopathology. In this context, we have earlier shown that Candida albicans associated with hyphae-secreted aspartyl proteinases (specifically SAP4-6) contribute to the immunopathology of the disease. Transcriptome profiling has revealed that non-coding transcripts regulate protein synthesis post-transcriptionally, which is important for the growth of Candida spp. Other studies have employed RNA sequencing to identify differences in the 1,245 Candida genes involved in surface and invasive cellular metabolism regulation. In vitro systems allow the simultaneous processing of a large number of samples, making them an ideal screening technique for estimating various physicochemical parameters, testing the activity of antimicrobial agents, and analyzing genes involved in biofilm formation and regulation (in situ) in specific strains. Murine VVC models are used to study C. albicans infection, especially in trials of novel treatments and to understand the cause(s) for resistance to conventional therapeutics. This review on the clinical relevance of Candida biofilms in VVC focuses on important advances in its genomics, transcriptomics, and proteomics. Moreover, recent experiments on the influence of biofilm formation on VVC or RVVC pathogenesis in laboratory animals have been discussed. A clear elucidation of one of the pathogenesis mechanisms employed by Candida biofilms in vulvovaginal candidiasis and its applications in clinical practice represents the most significant contribution of this manuscript.

Validation of stable reference genes in Staphylococcus aureus to study gene expression under photodynamic treatment: a case study of SEB virulence factor analysis

Staphylococcal enterotoxin B (SEB), encoded by the seb gene, is a virulence factor produced by Staphylococcus aureus that is involved mainly in food poisoning and is known to act as an aggravating factor in patients with atopic dermatitis. Research results in animal infection models support the concept that superantigens, including SEB contribute to sepsis and skin and soft tissue infections. In contrast to antibiotics, antimicrobial photodynamic inactivation (aPDI) is a promising method to combat both bacterial cells and virulence factors. The main aims of this research were to (1) select the most stable reference genes under sublethal aPDI treatments and (2) evaluate the impact of aPDI on seb. Two aPDI combinations were applied under sublethal conditions: rose bengal (RB) and green light (λ_max = 515 nm) and new methylene blue (NMB) and red light (λ_max = 632 nm). The stability of ten candidate reference genes (16S rRNA, fabD, ftsZ, gmk, gyrB, proC, pyk, rho, rpoB and tpiA) was evaluated upon aPDI using four software packages—BestKeeper, geNorm, NormFinder and RefFinder. Statistical analyses ranked ftsZ and gmk (RB + green light) and ftsZ, proC, and fabD (NMB + red light) as the most stable reference genes upon photodynamic treatment. Our studies showed downregulation of seb under both aPDI conditions, suggesting that aPDI could decrease the level of virulence factors.

Perillaldehyde: A promising antifungal agent to treat oropharyngeal candidiasis

Perillaldehyde (PAE), a natural monoterpenoid agent extracted from Perilla frutescence, PAE has been reported to present various physiological capabilities, such as anti-inflammation, anti-oxidative and anti-fungal. In this study, we show that PAE exhibits strong antifungal activity against Candida albicans (C. albicans). C. albicans, a fungal pathogen with high incidence of antifungal resistance in clinical settings, is the major cause of oropharyngeal candidiasis (OPC). OPC is characterized by inflammatory immunological responses to fungal infections. Our in vitro results show PAE inhibited several virulence attributes of C. albicans including biofilm formation, yeast-to-hyphal transition and secreted aspartic proteinases (SAPs) gene expression. Using an experimental murine model of OPC, we found that PAE inhibited NLRP3 inflammasome assembly, reduced the excessive accumulation of ROS and prevented the p65 transfer in nuclear; processes all leading to reduced inflammation burden in the host. Together, this supports use PAE as a promising new agent to improve OPC.

Antimicrobial photodynamic therapy reduces gene expression of Candida albicans in biofilms

The present study evaluated whether the oxidative stress caused by antimicrobial photodynamic therapy (aPDT) affects the expression of C. albicans genes related to adhesion and biofilm formation (ALS1 and HPW1) and oxidative stress response (CAP1, CAT1, and SOD1). The aPDT was mediated by two photosensitizing agents (PSs) Photodithazine® (PDZ at 100 and 200 mg/L) or Curcumin (CUR at 40 and 80 μM) and LED (37.5 J/cm² or 50 J/cm²). The quantification of the expression was performed by Reverse Transcription-Quantitative Polymerase Chain Reaction (RT-qPCR) using specific primers for the target genes. The data were analyzed by Analysis of Variance (α = 0.05), followed by Tukey's post-test. It was observed reduction in the expression of ALS1, HWP1, CAP1, CAT1, and SOD1 when aPDT was performed using 200 mg/L PDZ and 80 μM CUR associated to LED (37.7 and 50 J/cm², respectively) and using 100 mg/L PDZ and 40 μM CUR with LED of 50 J/cm² (versus control). Also, the expression of CAP1 and SOD1 genes was reduced after aPDT using 100 mg/L PDZ and LED of 37.5 J/cm². There was a significant reduction in the expression of genes HWP1, CAP1, and SOD1 after aPDT using 40 μM CUR and 37.5 J/cm² (versus the control group). The application of LED only at 37.5 and 50 J/cm² promoted down-regulation of ALS1, CAP1, CAT1, and SOD1 genes (versus the control group). Therefore, aPDT mediated by LED -associated PSs PDZ and CUR promoted a reduction in the expression of the five C. albicans genes evaluated.

Applying the Host-Microbe Damage Response Framework to Candida Pathogenesis: Current and Prospective Strategies to Reduce Damage

Disease is a complex outcome that can occur as a result of pathogen-mediated damage, host-mediated damage or both. This has led to the revolutionary concept of the damage response framework (DRF) that defines microbial virulence as a function of host immunity. The DRF outlines six scenarios (classes) of host damage or beneficial outcomes, depending on the microbe and the strength of the immune response. Candida albicans is uniquely adapted to its human host and can exist as either a commensal, colonizing various anatomical sites without causing notable damage, or as a pathogen, with the ability to cause a diverse array of diseases, ranging from mucosal to invasive systemic infections that result in varying levels of microbe-mediated and/or host-mediated damage. We recently categorized six different forms of candidiasis (oropharyngeal, hematogenous, intra-abdominal, gastrointestinal, denture stomatitis, and vulvovaginitis) into independent DRF classes, supporting a contemporary view of unique mechanisms of pathogenesis for these Candida infections. In this review, we summarize the evidence for the pathogenesis of these various forms of candidiasis in the context of the DRF with the further intent to provide insights into strategies to achieve a level of host response or outcome otherwise, that limits host damage.

Antifungal effect of photodynamic therapy mediated by curcumin on Candida albicans biofilms in vitro

BACKGROUND

Canida albicans can cause opportunistic infections ranging from superficial mucous membrane lesions to life-threatening disease. The aim of this study is to investigate the antifungal effect of photodynamic therapy (PDT) mediated by curcumin (CUR) on C. albicans biofilms in vitro.

METHODS

One standard strain ATCC 90028 and two clinical isolates from HIV (CCA1) and oral lichen planus (CCA2) patients' oral cavities were used in this study. Biofilms were photosensitized with 60 μM CUR and irradiated by light emitting diode (LED) under the wavelength of 455 nm and energy densities of 2.64, 5.28, 7.92, 10.56, 13.2 J/cm². Then the antifungal effects of CUR-PDT were evaluated by XTT reduction assay and confocal light scanning microscopy (CLSM) observations. The effects of CUR-PDT on the expression levels of hypha-specific and biofilm-related genes including EFG1, UME6, HGC1 and ECE1 were assessed by quantitative Real-time PCR (qRT-PCR) method.

RESULTS

The inhibition rates after CUR-PDT in three biofilms(ATCC 90028, CCA1, CCA2)were 90.87%, 66.44% and 86.74% respectively (p < 0.05). Relative gene expression levels of EFG1, UME6, HGC1 and ECE1 were all downregulated after CUR-PDT, with fold-decrease of 6.865, 3.382, 2.167 and 6.887 in ATCC 90028, 2.466, 2.146, 1.627 and 3.102 in CCA1, and 5.406, 2.347, 2.073and 3.711 in CCA2 (p < 0.05).

CONCLUSIONS

Curcumin-mediated PDT could effectively inactivateCandida albicans biofilms in vitro. Expression of genes involved in biofilms formation were downregulated after CUR-PDT.

Photodynamic therapy mediated by chlorin-type photosensitizers against Streptococcus mutans biofilms

Photodynamic therapy (PDT) can be used for the control of oral pathogens and different photosensitizers (PS) have been investigated. This study evaluated the efficacy of PDT against Streptococcus mutans biofilms using two second-generation PS derived from chlorin: Photoditazine® (PDZ) and Fotoenticine® (FTC). These PS were compared to methylene blue (MB), a dye with proven antimicrobial activity against S. mutans. Suspensions of S. mutans were cultured in contact with bovine tooth disks for biofilm formation. After 48 h, the biofilms were treated with PDZ (0.6 mg/mL), FTC (0.6 mg/mL) or MB (1 mg/mL) and submitted to laser irradiation (660 nm, 50 mW/cm²). The biofilms were quantified by the determination of CFU/mL count and analyzed by scanning electron microscopy (SEM). All PS used for PDT reduced the number of S. mutans, with a statistically significant difference compared to the untreated groups. PDT achieved microbial reductions of 4 log with MB and 6 log with PDZ, while the use of FTC resulted in the complete elimination of S. mutans biofilms. SEM analysis confirmed the CFU/mL results, showing that all PS, particularly FTC, were able to detach the biofilms and to eliminate the bacteria. In conclusion, PDT mediated by chlorin-type PS exhibited greater antimicrobial activity against S. mutans than MB-mediated PDT, indicating that these PS can be useful for the control of dental caries.