Abundance interaction in Candida albicans and Candida glabrata mixed biofilms under diverse conditions

Segmentation of hyphae and yeast in fungi-infected tissue slice images and its application in analyzing antifungal blue light therapy

Candida albicans is a pathogenic fungus that undergoes morphological transitions between hyphal and yeast forms, adapting to diverse environmental stimuli and exhibiting distinct virulence. Existing research works on antifungal blue light (ABL) therapy have either focused solely on hyphae or neglected to differentiate between morphologies, obscuring potential differential effects. To address this gap, we established a novel dataset of 150 C. albicans-infected mouse skin tissue slice images with meticulously annotated hyphae and yeast. Eleven representative convolutional neural networks were trained and evaluated on this dataset using seven metrics to identify the optimal model for segmenting hyphae and yeast in original high pixel size images. Leveraging the segmentation results, we analyzed the differential impact of blue light on the invasion depth and density of both morphologies within the skin tissue. U-Net-BN outperformed other models in segmentation accuracy, achieving the best overall performance. While both hyphae and yeast exhibited significant reductions in invasion depth and density at the highest ABL dose (180 J/cm2), only yeast was significantly inhibited at the lower dose (135 J/cm2). This novel finding emphasizes the importance of developing more effective treatment strategies for both morphologies.

Exploring the Complexity of the Interaction between T. rubrum and S. aureus/S. epidermidis in the Formation of Polymicrobial Biofilms

Dermatophytes associated with bacteria can lead to severe, difficult-to-treat infections and contribute to chronic infections. Trichophyton rubrum, Staphylococcus aureus, and Staphylococcus epidermidis can form biofilms influenced by nutrient availability. This study investigated biofilm formation by these species by utilizing diverse culture media and different time points. These biofilms were studied through scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), biomass, metabolic activity, and colony-forming units (CFUs). The results revealed that mixed biofilms exhibited high biomass and metabolic activity when cultivated in the brain heart infusion (BHI) medium. Both bacterial species formed mature biofilms with T. rubrum within 72 h, irrespective of media. The timing of bacterial inoculation was pivotal in influencing biomass and metabolic activity. T. rubrum's development within mixed biofilms depended on bacterial addition timing, while pre-adhesion influenced fungal growth. Bacterial communities prevailed initially, while fungi dominated later in the mixed biofilms. CLSM revealed 363 μm thick T. rubrum biofilms with septate, well-developed hyphae; S. aureus (177 μm) and S. epidermidis (178 μm) biofilms showed primarily cocci. Mixed biofilms matched T. rubrum's thickness when associated with S. epidermidis (369 μm), with few hyphae initially. Understanding T. rubrum and Staphylococcal interactions in biofilms advances antimicrobial resistance and disease progression knowledge.

Non-albicans Candida Species: Immune Response, Evasion Mechanisms, and New Plant-Derived Alternative Therapies

Fungal infections caused by Candida species have become a constant threat to public health, especially for immunocompromised patients, who are considered susceptible to this type of opportunistic infections. Candida albicans is known as the most common etiological agent of candidiasis; however, other species, such as Candida tropicalis, Candida parapsilosis, Nakaseomyces glabrata (previously known as Candida glabrata), Candida auris, Candida guilliermondii, and Pichia kudriavzevii (previously named as Candida krusei), have also gained great importance in recent years. The increasing frequency of the isolation of this non-albicans Candida species is associated with different factors, such as constant exposure to antifungal drugs, the use of catheters in hospitalized patients, cancer, age, and geographic distribution. The main concerns for the control of these pathogens include their ability to evade the mechanisms of action of different drugs, thus developing resistance to antifungal drugs, and it has also been shown that some of these species also manage to evade the host's immunity. These biological traits make candidiasis treatment a challenging task. In this review manuscript, a detailed update of the recent literature on the six most relevant non-albicans Candida species is provided, focusing on the immune response, evasion mechanisms, and new plant-derived compounds with antifungal properties.

Polymicrobial Biofilm Dynamics of Multidrug-Resistant Candida albicans and Ampicillin-Resistant Escherichia coli and Antimicrobial Inhibition by Aqueous Garlic Extract

The polymicrobial biofilm of C. albicans with E. coli exhibits a dynamic interspecies interaction and is refractory to conventional antimicrobials. In this study, a high biofilm-forming multidrug-resistant strain of C. albicans overcomes inhibition by E. coli in a 24 h coculture. However, following treatment with whole Aqueous Garlic Extract (AGE), these individual biofilms of multidrug-resistant C. albicans M-207 and Ampicillin-resistant Escherichia coli ATCC 39936 and their polymicrobial biofilm were prevented, as evidenced by biochemical and structural characterization. This study advances the antimicrobial potential of AGE to inhibit drug-resistant C. albicans and bacterial-associated polymicrobial biofilms, suggesting the potential for effective combinatorial and synergistic antimicrobial designs with minimal side effects.

Down-regulation of microRNA-155 suppressed Candida albicans induced acute lung injury by activating SOCS1 and inhibiting inflammation response

Acute lung injury caused by Candida albicans could result in high mortality and morbidity. MicroRNA-155 (miR-155) and suppressor of cytokine signaling 1 (SOCS1) have been believed to play a key in the regulation of inflammatory response. Whether miR-155/SOCS1 axis could regulate the acute lung injury caused by C. albicans has not been reported. The acute lung injury animal model was established with acute infection of C. albicans. miR-155 inhibitor, miR-155 mimic, and sh-SOCS1 were constructed. The binding site between miR-155 and SOCS1 was identified with dual luciferase reporter assay. Knockdown of miR-155 markedly inhibited the germ tube formation of C. albicans. Knockdown of miR-155 significantly up-regulated the expression of SOCS1, and the binding site between miR-155 and SOCS1 was identified. Knockdown of miR-155 improved the acute lung injury, suppressed inflammatory factors and fungus loading through SOCS1. Knockdown of SOCS1 greatly reversed the influence of miR-155 inhibitor on the cell apoptosis in vitro. The improvement of acute lung injury caused by C. albicans, suppression of inflammatory response and C. albicans infection, and inhibitor of cell apoptosis were achieved by knocking down miR-155 through SOCS1. This research might provide a new thought for the prevention and treatment of acute lung injury caused by C. albicans through targeting miR-155/SOCS1 axis.

Sodium houttuyfonate enhances the mono-therapy of fluconazole on oropharyngeal candidiasis (OPC) through HIF-1α/IL-17 axis by inhibiting cAMP mediated filamentation in Candida albicans-Candida glabrata dual biofilms

Candida albicans and Candida glabrata are two common opportunistic fungi that can be co-isolated in oropharyngeal candidiasis (OPC). Hypha is a hallmark of the biofilm formation of C. albicans, indispensable for the attachment of C. glabrata, which is seldom in mycelial morphology. Increasing evidence reveals a hypoxic microenvironment in interior fungal biofilms, reminding of a fact that inflammation is usually accompanied by oxygen deprivation. As a result, it is assumed that the disaggregation of hypha-mediated hypoxia of biofilms might be a solution to alleviate OPC. Based on this hypothesis, sodium houttuyfonate (SH), a well-identified traditional herbal compound with antifungal activity, is used in combination with fluconazole (FLU), a well-informed synthesized antimycotics, to investigate their impact on filamentation in C. albicans and C. glabrata dual biofilms and the underlying mechanism of their combined treatment on OPC. The results show that compared with the single therapy, SH plus FLU can inhibit the hyphal growth in the mixed biofilms in vitro, decrease the fungal burden of oral tissues and internal organs, restore mucosal epithelial integrity and function, and reduce hypoxic microenvironment and inflammation in a mice OPC model. The possible mechanism of the combined therapy of SH plus FLU can be attributed to the regulation of HIF-1α/IL-17A axis through direct abrogation of the dual Candida biofilm formation. This study highlights the role of HIF-1α/IL-17A axis and the promising application of SH as a sensitizer of conventional antifungals in the treatment of OPC.