A new study shows that a bacterial intestinal infection is contrary to most expectationshealth benefitscould bring with it. Mice infected with bacteria or parasites in research developed a unique form of tolerance that is very different from the immune response. The published study results also describe how intestinal macrophages respond to a previous attack by shielding the enteric nervous system. Additionally, this prevents enteric neurons from dying when future pathogens strike.
The protective effect that a bacterial intestinal infection can have
The new scientific findings could have clinical implications for diseases such as irritable bowel syndrome, which are linked to the uncontrolled death of intestinal neurons. The enteric nervous system, known as the “second brain,” houses the largest depot of neurons and glial cells outside the brain. The gastrointestinal tract's own nervous system therefore exists more or less autonomously, without any significant contribution from the brain. It also controls the movement of nutrients and coordinates local fluid exchange and blood flow. It does this with an authority not seen anywhere else in the peripheral nervous system. However, when a majority of these neurons die, the gastrointestinal tract goes out of control. The study authors now wanted to find out whether the body has a mechanism that could prevent the loss of nerve cells after an infection. The scientists found that repeated parasitic or bacterial intestinal infections can also prevent neuronal loss.
Unlike pathogenic bacteria, some parasites such as gastrointestinal helminths have learned not to harm intestinal tissue, the researchers said. In fact, this family of parasites, which includes leeches, tapeworms and nematodes, infects in more subtle ways than hostile bacteria. This means they provide even greater and more far-reaching protection. Now the research team hopes to determine the exact effects of neuronal loss in the gastrointestinal tract. People who fail to develop tolerance for some reason may lose enteric neurons with each subsequent infection throughout their lives. Future studies will explore alternative methods of protecting enteric neurons and hopefully pave the way for therapies. In addition, the authors believethis studythat the findings could contribute to a more comprehensive understanding of the underlying causes of irritable bowel syndrome and related intestinal diseases.
