Immune sentries protect gut from bugs by sensing vitamins

3 Apr 2014

Australian researchers have identified a biochemical key that alerts immune cells to the presence of bacteria and fungi, which could lead to new ways of diagnosing and treating diseases such as inflammatory bowel disease, peptic ulcers and even infections like tuberculosis.

The discovery, made by scientists from the Universities of Queensland, Melbourne, Monash and Cork, provides a starting point for understanding a human’s first line of immune defence and what causes it to go wrong in disease. 

The team had previously found that a type of immune cell, known as mucosal-associated invariant T cells (MAITs), could detect molecules produced by bacteria and fungi when manufacturing vitamin B2, also known as riboflavin.

Bacteria synthesise vitamin B2 for their growth whereas humans are unable to make this vitamin. 

The researchers have now pinpointed the exact chemicals that activate these special human immune cells, which act as red flags to the immune system.

Professor David Fairlie, from UQ’s Institute for Molecular Bioscience, said this finding may be very important for understanding the body’s reaction to some bacterial infections. 

“Essentially this is a way of sensing the presence of bacteria and mounting an immune response, without interfering with nutrition,” Professor Fairlie said.

“This may be a valuable clue to previously unknown mechanisms of immunity and possibly disease pathology, and could lead to entirely new drug development strategies.

He acknowledged Dr Ligong Liu and Dr Jeff Mak, also from UQ’s Institute for Molecular Bioscience, who synthesised and isolated the unstable chemicals that trigger activation of these T cells.

Other senior authors on the paper, published overnight in world-leading scientific journal Nature, were Professor Jim McCluskey from The University of Melbourne and Professor Jamie Rossjohn from Monash University.

“This is an excellent example of how collaborative research in Australia can bring groups with expertise in different areas together to make significant advances,” Professor McCluskey, Deputy Vice-Chancellor (Research) of The University of Melbourne, said.

The work is an early win for the recently announced Australian Research Council Centre of Excellence in Advanced Molecular Imaging.

“We want to unravel the complex molecular interactions that define how we fight disease,” Professor Rossjohn said.

“This remarkable research collaboration shows us how to do it.”

Media contact: IMB Communications Manager Bronwyn Adams, 0418 575 247, 07 3346 2134,