Mechanism behind oral candidiasis discovered
LONDON, UK/PITTSBURGH, US: A recently discovered peptide toxin has been identified by a team of UK and US researchers as the cause of the development of oral candidiasis, also known as oral thrush. The substance, called “Candidalysin”, which is produced by the Candida albicans fungus, was found to punch a hole into cells lining the mouth, thus triggering the immune response.
Helper immune cells then attack the otherwise harmless fungus, resulting in the painful infection, they wrote in a study published by the Science Immunology journal.
“Surprisingly little is known about how fungal immunity in the mouth operates,” said co-senior author Dr Sarah L. Gaffen from the University of Pittsburgh School of Medicine in the US, “and, until now, it was unclear why Candida does not establish an invasive infection in healthy humans.”
In their study, the researchers used a combination of human oral epithelial cells cultured in laboratory dishes and mice infected orally with Candida, to show the central importance of Candidalysin. Discovered in 2016 by Prof. Julian Naglik of King’s College London in the UK, the toxin is the first peptide toxin identified in any fungus that was found to infect humans. Understanding its role in the infection mechanism in the mouth could eventually lead to better treatments for the condition and other fungal infections, the scientists said.
They added that, despite millions of fungal infections worldwide, there are no commercially available anti-fungal vaccines.
“Our research provides vital clues to understand the immune defence network at barrier sites of the body. This knowledge may ultimately be harnessed to design antifungal vaccines,” said Naglik.
Recently awarded a large National Institutes of Health grant, Gaffen and Naglik announced their further exploration of the role of Candidalysin signalling in oral immunity in the near future.
Oral candidiasis is one of the most common fungal infections of the mouth. While it is treatable with topical medication, it often causes pain that makes it difficult for patients to eat or swallow. It is also believed to be responsible for other serious fungal infections, especially in infants and other patients with a compromised immune system, such as HIV/Aids patients, denture wearers and those on immunosuppressants, including chemotherapy and drugs to prevent the rejection of transplanted organs.
The paper, titled “Oral epithelial cells orchestrate innate Type 17 responses to Candida albicans through the virulence factor Candidalysin”, was published in Science Immunology on 3 November.