Human intestine harbors about 100 trillion bacteria. Some are beneficial to body in splitting some types of food for easier digestion and even synthesizing vitamins for the host. Some of bacteria though remain silent may attack the host when get opportunity. In addition to the host of bacteria in the intestine, many more bacteria and virus enter the gut daily though various ways.
It is interesting that those do not always cause disease. So, it appears that some defense mechanism is in place to protect the gut from invasion of the microbes.
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Researchers found out that a protein of lectin family RegIII and in particular RegIIIY is responsible for keeping the pathogens in a safe distance from the cells of gut. This protein can damage the bacteria, so is bactericidal.
This protein is secreted from the gut cells and creates a buffer zone of 50 micrometers between the cells of gut and the bugs present in the gut lumen.
When this defense is weakened or suppressed the microbes come in contact with the cells of the inner layer of gut; and set infection and inflammation.
The impaired regulation of RegIII antibacterial activity in human populations could result in compromised intestinal immunity and a predisposition to enteric infections and inflammation.
It also has been seen that RegIII acts against gram positive bacteria; therefore, it is likely that other such type of defense may be in place to protect gut from gram negative bacteria and other microbes.
Perhaps, more research may through light on this gut defense mechanism and potential treatment modalities for IBD may emerge from it.