In trying to find out why probiotics were more effective in keeping IBD in remission, and less effective in dealing with its onset, they isolated iron as the likely culprit as the mineral’s levels rise during a bout of IBD.
Because probiotics like Lactobacillus and Bifidobacterium are lactic acid bacteria, their growth is inhibited by the iron levels, the researchers concluded.
The Uni of Bristol team has isolated and patented a strain that demonstrated the ability to perform immune functions and pro-inflammatory responses in the presence of high iron levels during active IBD events like Crohn’s disease and ulcerative colitis.
"When we started our study we considered the properties that a probiotic would need to treat IBD,” said Dr Tristan Cogan, research fellow in the School of Veterinary Sciences at Bristol University.
“Most importantly, it would need to be able to survive and grow in the presence of high levels of iron and to reduce inflammation. We then worked out how to test bacteria to see whether it had these properties.”
"The difficult step was finding a bacterium that had all of the properties that we wanted. Now we have found something that looks like it should work, our next step will be to test the probiotic in clinical trials."
Lactic acid bacteria are unlike many other bacteria and pathogens in that they do not require iron to spur growth. Some pathogens increase growth by multiples of 1000s in the presence of iron.
Other research conducted by a team at the Institut Pasteur de Lille in France found proteins on the surface of some probiotic bacteria like Lactobacillus could boost their ability to battle IBD.
Certain proteins on the surface of the strains interact with a receptor on the wall of the intestine to produce an inflammatory response, they suggested.
However strains that do not have this active protein – called peptidoglycan or PGN – on their surface were unable to react with the receptors (called NOD2) and were not associated with any protective properties.
The latest developments in probiotic research will be discussed at the Microbiota two-day conference in Paris on December 13-14. For more information click here.
Published online 19 October
‘Identification and characterisation of an iron-responsive candidate probiotic’
Authors: Jennifer R. Bailey, Christopher S.J. Probert and Tristan A. Cogan.