"Cell" reveals new functions of the nervous system in the face of bacterial infections

Scientists from Harvard Medical School published a rather surprising study online in the journal Cell In the traditional impression, the nervous system is only the receiver and transmitter of information But in this paper, scientists point out that it has changed its "Yes No" attitude in the fight against bacterial infection, and has chosen to fight hard Specifically, the study focused on a structure called Peyer's patches This is a structure that only exists on the wall of the small intestine It consists of lymphoid tissue and immune tissue In terms of function, it can "scan" the intestinal environment and decide what to swallow into the intestine We can get so much nutrition, not all kinds of waste, thanks to their help So how does this structure know what to eat? It turns out that there are some special "M cells" on them They are like doors that open when they encounter nutrients and close when they encounter harmful substances This mechanism may seem sophisticated, but it can be used by harmful bacteria For example, Salmonella will secrete transcription factors, promote the formation of more M cells, and create more gates Later, they will forcibly open these openings to allow more Salmonella to invade the intestine According to the Centers for Disease Control and Prevention (CDC), more than one million people are infected with Salmonella every year, and on average, people die every day Read here, some friends may ask, what does this have to do with the nervous system? Don't worry, it's time for the nervous system to show up In order to study whether pain sensing gut neurons can protect against bacterial infection, the researchers conducted a comparative experiment: one group of mice had complete neuron function, and the other two groups of mice had lost neuron function (using genetic means and chemical hand segments respectively) Interestingly, those mice with complete neuronal function had better resistance to Salmonella The reason behind this is quite unexpected - these neurons directly secrete peptide called CGRP, which is related to migraine attack in the brain In the gut, it also gives Salmonella a "headache." It turns out that this peptide can inhibit the production of M cells, which virtually reduces the invasion point of Salmonella In addition, CGRP can promote the growth of segmentous filamentous bacteria This kind of bacteria and Salmonella can be said to be dead rivals, which will inhibit the latter's invasion of the intestine "It's clear that the nervous system acts directly on infectious organisms and regulates immunity in many ways." Professor Isaac M Chiu, the study's co-author, said The researchers also pointed out that this could explain why some people who abuse painkillers are more likely to develop infections In addition, we also hope to find a way to fight against intestinal infection or inflammation by regulating neural signals "Our findings suggest that the nervous system is more than a simple 'sense and alarm' system In the gut, nerve cells do more than that They can also regulate the immune capacity of the gut, maintain the intestinal homeostasis, and actively provide protection against infection " Professor Chiu concluded