Immune study shows how gut keeps deadly infections at bay
March 2016: How the immune system stops bacteria in our gut from leaking into the blood stream and causing body-wide inflammation
Researchers at the MRC Centre for Inflammation Research at The University of Edinburgh have discovered how the immune system stops bacteria in our gut from leaking into the blood stream and causing body-wide inflammation, such as sepsis. The study also helps to explain why we do not suffer more infections, despite the vast number of bacteria that are found naturally in our gut.
A study led by Dr Rodger Duffin and Dr Chengcan Yao has discovered a mechanism that helps to keep bacteria in the gut. They found that a small molecule called PGE2 plays a crucial role by activating specialised immune cells called innate lymphoid cells. These cells help to maintain the barrier between the gut and the rest of the body. If PGE2 is blocked or does not function correctly, these cells are not activated and the gut barrier breaks down allowing bacteria to escape.
The researchers also showed that PGE2 triggers innate lymphoid cells to produce a chemical called IL-22, which helps to prevent the breakdown of the gut barrier and stop body-wide inflammation. The findings could lead to new approaches for preventing whole-body infections, which can be life-threatening if they are not caught early. These infections sometimes called sepsis or septicaemia are one of the biggest killers of critically ill patients.
The study, published in the journal Science, was primarily funded by the Medical Research Council and the Wellcome Trust from the UK.
Duffin R, O'Connor RA, Crittenden S, Forster T, Yu C, Zheng X, Smyth D, Robb CT, Rossi F, Skouras C, Tang S, Richards J, Pellicoro A, Weller RB, Breyer RM, Mole DJ, Iredale JP, Anderton SM, Narumiya S, Maizels RM, Ghazal P, Howie SE, Rossi AG, Yao C. (2016) Prostaglandin E₂ constrains systemic inflammation through an innate lymphoid cell-IL-22 axis. Science;351(6279):1333-8.
doi: 10.1126/science.aad9903. PMID: 26989254