An insight into the role of protein kinases as virulent factors, regulating pathogenic attributes in Candida albicans

Candida albicans and Antifungal Peptides

Candida albicans, a ubiquitous opportunistic fungal pathogen, plays a pivotal role in human health and disease. As a commensal organism, it normally resides harmlessly within the human microbiota. However, under certain conditions, C. albicans can transition into a pathogenic state, leading to various infections collectively known as candidiasis. With the increasing prevalence of immunocompromised individuals and the widespread use of invasive medical procedures, candidiasis has become a significant public health concern. The emergence of drug-resistant strains further complicates treatment options, highlighting the urgent need for alternative therapeutic strategies. Antifungal peptides (AFPs) have gained considerable attention as potential candidates for combating Candida spp. infections. These naturally occurring peptides possess broad-spectrum antimicrobial activity, including specific efficacy against C. albicans. AFPs exhibit several advantageous properties, such as rapid killing kinetics, low propensity for resistance development, and diverse mechanisms of action, making them promising alternatives to conventional antifungal agents. In recent years, extensive research has focused on discovering and developing novel AFPs with improved efficacy and selectivity against Candida species. Advances in biotechnology and synthetic peptide design have enabled the modification and optimization of natural peptides, enhancing their stability, bioavailability, and therapeutic potential. Nevertheless, several challenges must be addressed before AFPs can be widely implemented in clinical practice. These include optimizing peptide stability, enhancing delivery methods, overcoming potential toxicity concerns, and conducting comprehensive preclinical and clinical studies. This commentary presents a short overview of candidemia and AFP; articles and reviews published in the last 10 years were searched on The National Library of Medicine (National Center for Biotechnology Information-NIH-PubMed). The terms used were C. albicans infections, antimicrobial peptides, antifungal peptides, antifungal peptides mechanisms of action, candidemia treatments and guidelines, synthetic peptides and their challenges, and antimicrobial peptides in clinical trials as the main ones. Older publications were cited if they brought some relevant concept or helped to bring a perspective into our narrative. Articles older than 20 years and those that appeared in PubMed but did not match our goal to bring updated information about using antifungal peptides as an alternative to C. albicans infections were not considered.

Autophagy Alters the Susceptibility of Candida albicans Biofilms to Antifungal Agents

Candida albicans (C. albicans) reigns as a major cause of clinical candidiasis. C. albicans biofilms are known to increase resistance to antifungal agents, making biofilm-related infections particularly challenging to treat. Drug resistance is of particular concern due to the spread of multidrug-resistant fungal pathogens, while autophagy is crucial for the maintenance of cellular homeostasis. Therefore, this study aimed to investigate the effects of an activator and an inhibitor of autophagy on the susceptibility of C. albicans biofilms to antifungal agents and the related mechanisms. The susceptibility of C. albicans biofilms to different antifungal agents after treatment with or without the autophagy activator or inhibitor was evaluated using XTT assay. Alkaline phosphatase (ALP) activity and reactive oxygen species (ROS) level, as well as the expression of ROS-related and autophagy-related genes, were examined to evaluate the autophagic activity of C. albicans biofilms when treated with antifungal agents. The autophagosomes were observed by transmission electron microscopy (TEM). The susceptibility of C. albicans biofilms to antifungal agents changed when autophagy changed. The ALP activity and ROS level of C. albicans biofilms increased with the treatment of antifungal agents, and autophagosomes could be observed in C. albicans biofilms. Autophagy was involved in the susceptibility of C. albicans biofilms to antifungal agents.

Oxidative stress-triggered pyroptosis mediates Candida albicans susceptibility in diabetic foot

An accumulating trend of research demonstrates that diabetic patients are susceptible to skin infections with Candida albicans, but the mechanism still remains unclear. The intense oxidative stress (OS) responses were occurred in the lesion of diabetic mice footpads after C. albicans infection. Localised skin infections would lead to more severe complications while the severity of the condition worsens or the inadequate treatment. Notably, in this study, through the investigation of murine diabetic footpad C. albicans infection model and molecular biotechnology, including histopathological staining, immunofluorescence (IF) staining, quantitative real-time PCR (qPCR), western blot (WB), flow cytometry (FCM), sandwich enzyme-linked immunosorbent assay (ELISA) assays, we found that intense OS responses in the footpad tissue not only mediated the activation of NF-κB protein complex, but also triggered downstream pyroptosis and apoptosis through NLRP3 inflammasome, which is one of the potential reasons for the severe condition of infectious skin injuries in diabetic mice. Caspase-1, a classical signal pathway protein in pyroptosis, could promote pore formation on cell membranes and the release of the cytokine after NLRP3 inflammasome activation. With intense immune-inflammatory responses, the organism also stimulates immune organs such as the spleen and lymph nodes to produce negative feedback regulation and generate CD4⁺CD25⁺Foxp3⁺ Treg cells to rectify the process. Therefore, combined with the results of this work, it is possible to design and screen relevant drugs for NLRP3 inflammasomes as core targets to keep the OS response at a low level in the footpad tissues.