Advanced imaging sheds light on the immune evasion of a shape-shifting fungus

A microscopy assay developed by Olivier et al. captures the release of a fungus (C. albicans) from immune cells (macrophages). Left: Fungi (red) inside immune cells. Right: detached filaments of the fungus (blue) and nuclei of dead immune cells (green). Credit: Monash University

Fungal pathogens have a major global impact on human health – they are often difficult to diagnose and treat, and there is an urgent need for better diagnostics and more effective antifungal treatments. Using new imaging technology, researchers at the Monash Institute for Biomedical Discovery today showed how Candida albicans, a common fungus, evades immune responses. According to the researchers, this includes an “alien” that allows the fungus to escape from immune cells.

The document is published in the journal Cell reports, led by Prof. Ana Traven and Ph.D. student, François Olivier, describes how Candida albicans uses a sword-like thread to engage toxin molecules and cell death pathways that damage the cell membranes of the immune system, allowing it to break free and spread.

The imaging technology, developed by Olivier in collaboration with Monash Micro-Imaging, enables the real-time detection of escaping fungi. According to Olivier, this study was made possible by the automation of image analysis and increased computer processing power: “We were able to use a large amount of data that gave insight into this immune escape mechanism.”

Candida is a yeast that often lives in the human digestive tract and mouth, as well as in the urinary and reproductive organs. As a rule, it does not cause disease in the host, but under certain conditions it can turn into a harmful form. Candida albicans remains a common cause of life-threatening disease in intensive care, post-surgical and cancer patients. The immune system has a specific type of cell called a macrophage, which is responsible for engulfing invaders (bacteria, fungi, cancer cells) and triggering immune responses. Candida albicans evades macrophages by transforming into long filamentous cells. Such an escape leads to the spread of the fungus. In the process, this triggers immune responses that can be harmful if left unchecked.

According to Professor Traven, fighting the fungus when it escapes “represents a promising therapeutic avenue that both prevents the spread of infection and has the potential to reduce inflammation.” Until now, the mechanisms of this escape have remained unclear, as researchers have not been able to study this escape maneuver in detail. Now they can. The research team developed a live-cell imaging platform that maps Candida egress from macrophages in real time, revealing multiple egress mechanisms.

Gut cells and lactic acid bacteria work together to protect against Candida infections

Additional information:
Ana Traven, Candida albicans exit from macrophages is mediated by the fungal toxin candidolysin and two pathways of host cell death. Cell reports (2022). DOI: 10.1016/j.celrep.2022.111374

Monash University

Citation: Advanced imaging sheds light on immune evasion of shape-shifting fungus (September 20, 2022) Retrieved September 20, 2022, from shifting fungus. html

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