The role of fungi in Crohn’s Disease

What is this research looking at? 

Several factors are thought to be involved in Crohn’s Disease. One of these is an abnormal reaction of the immune system to certain bacteria in the intestines, which may be triggered by something in the environment.  Bacteria and its role in Crohn’s is therefore an area of interest in IBD research. 

Bacteria in the intestine of people with Crohn’s are different to bacteria in those without the condition. People with Crohn’s have fewer varieties of bacteria, and some ‘good bacteria’ – which help the gut – are missing, while some ‘bad bacteria’ are not killed.  A westernised diet can influence the bacteria that live in the intestine, which may be a possible explanation for the rise in Crohn’s Disease as countries continue to develop.    

Fungi may also live in the intestine, but little is known about them at the moment.  It is thought that there are more fungi in the gut of those with Crohn’s than in those without.  Many people with Crohn’s in their small intestine have antibodies (proteins that identify and neutralise harmful invaders) specific to some fungi, whereas these are uncommon in people without Crohn’s. The researchers previously found chemical markers from fungi in the stool of people with Crohn’s more commonly than in those without the condition. They also found that some components of fungi stop bacteria being killed – failure to kill certain types of bacteria is common in Crohn’s of the small intestine.  This suggests fungi play a role in Crohn’s.  

This research aimed to further investigate the role of fungi in Crohn’s. Researchers planned to discover which types of fungi are found in people with Crohn’s, and to find out if the presence of fungi affects the bacteria in the intestine, by suppressing ‘good bacteria’ and stopping the killing of ‘bad bacteria’ associated with Crohn’s. The researchers hoped their findings would also lead to a better understanding of why some patients relapse, and that new treatment options could be suggested, based on suppressing fungi by diet or drugs. They used various samples from two different study groups to obtain their data. 

Conclusions:

Two main discoveries were made from this research: 

1. The intestine of people with Crohn’s was found to be populated with high numbers of Saccharomyces (a yeast) in both study groups, and Candida (another type of yeast) in one study group.  The western diet tends to contain a large amount of yeasts, especially Saccharomyces, which has been found to trigger inflammation in mice.    
2. Where Saccharomyces was found in high numbers, there was a reduction in a type of ‘good’ bacteria called Faecalibacterium.  Therefore Saccharomyces may negatively affect the relationship between Crohn’s and ‘good bacteria’, however this needs further investigation. 

What do the researchers think this could mean for people with IBD? 

The researchers have identified a yeast that is present in high numbers in people with Crohn’s, which reduces the amount of some ‘good bacteria’ in the gut.  Further investigation into this yeast and how it affects the bacteria in the gut is needed.  This could lead to the development of new treatment options such as specific changes to diet. 

Who is leading the research: Professor Chris Probert, Institute of Translational Medicine, University of Liverpool 

Award amount: £119,256 (£60,615 Year 1; £58,641 Year 2) - funded by forCrohns.
Duration: 24 months
Official title of the application: Examination of the fungal microbiome in Crohn’s disease and an investigation of the impact of fungi on bacterial microbiota and their interaction with phagocytic leucocytes
Tags: Fungi / Bacteria