Researchers at the University of Gothenburg described a new type of cell located in the intestine. These so-called sentinel cells keep an eye out for invading bacteria and sacrifice themselves to protect you. And they say chivalry is dead.
This same group, led by Gunnar C. Hansson, previously showed that the gut produces a layer of mucus to keep the intestinal tissue from coming into direct contact with bacteria.
This protective mucus layer is produced by goblet cells that line the inner surface of the intestine. This surface also contains depressions called crypts - the crypts shelter stem cells that make new intestinal cells.
Sometimes, however, bacteria manage to penetrate the mucus layer. This is when the sentinel cells step up to the plate. According to study author George Birchenough, “these cells are like sentinels guarding the entrance to the crypt. As soon as they discover traces of bacteria in the crypt opening, it starts a chain reaction ending up in a violent mucus explosion that washes away the bacteria”.
Go on, take a moment to clear the image of “violent mucus explosion” from your head.
The group wanted to be sure that the sentinel cells were actually reacting to the presence of bacteria. Indeed, they showed that the cells secreted mucus in response to bacterial TLR ligands such as LPS and flagellin, suggesting that the mucus explosions are a specific response to bacteria.
As if orchestrating a violent mucus explosion isn’t enough, the sentinel cells sacrifice themselves to flush away the invading bacteria. “When the sentinel goblet cell is emptied, it pushes itself out as a catapult”, says Hansson. “If this does not prevent the bacterial attack, and this continues, there are no new sentinels to send forward, thus leaving the crypt open for bacterial invasion and the potential onset of inflammatory bowel diseases such as ulcerative colitis”.
Thus, these findings may inform our understanding of inflammatory bowel disease and point towards new treatment strategies - people with inflammatory bowel disease may have less chivalrous sentinel cells, for example.
Sources: Science, Science Daily