Researchers 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.
Our gut carries more than ten times as many bacteria than there are cells in our body. They are normally good for us as they help us to digest food and stave off infections with other types of bacteria that cause disease.
If, however, the bacteria escape from the gut into the blood stream, they can cause infections elsewhere in the body that become deadly if left untreated.
Their escape is triggered by an immune system failure that causes a massive inflammatory response. This damages healthy tissues and can lead to multiple organ failure.
Authors found that a small molecule called PGE2 plays a crucial role by activating specialized immune cells called innate lymphoid cells. These cells help to maintain the barrier between the gut and rest of the body.
If PGE2 is blocked or doesn't 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.
PGE2 is one of a family of molecules called prostaglandins that are blocked by common anti-inflammatory drugs, including aspirin and ibuprofen.
The findings could lead to new approaches for preventing whole-body infections, which can be life-threatening if they are not caught early.
Mechanism that helps to keep bacteria in the gut
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