New research by scientists at Harvard Medical School has found that nerves in the guts of mice do not merely sense the presence of Salmonella but actively protect against infection by this dangerous bacterium by deploying two lines of defense.
The study, which will be published Dec. 5 in Cell, casts in a new light the classic view of the nervous system as a mere watchdog that spots danger and alerts the body to its presence. The results show that by directly interfering with Salmonella's ability to infect the intestines, the nervous system is both a detector of danger and a defender against it.
"Our results show the nervous system is not just a simple sensor-and-alert system," said neuro-immunologist Isaac Chiu, the study's lead investigator and assistant professor of immunology in the Blavatnik Institute at Harvard Medical School. "We have found that nerve cells in the gut go above and beyond. They regulate gut immunity, maintain gut homeostasis and provide active protection against infection."
Specifically, the experiments reveal that pain-sensing neurons embedded in the small intestine and beneath cells called Peyer's patches are activated by the presence of Salmonella, a foodborne bacterium responsible for a quarter of all bacterial diarrheal disease worldwide.
Once activated, the nerves use two defensive tactics to prevent the bug from infecting the intestine and spreading throughout the rest of the body. First, they regulate the cellular gates that allow microorganisms and various substances to go in and out of the small intestine. Second, they boost the number of protective gut microbes called SFB (segmented filamentous bacteria), which are part of the microbiome in the small intestine.
[...] The new findings add to a growing body of knowledge showing that the nervous system has a repertoire far broader than signaling to and from the brain.
"Our findings illustrate an important cross talk between the nervous system and the immune system," said study first author Nicole Lai, research fellow in immunology in the Chiu lab. "It is clearly a bidirectional highway with both systems sending messages and influencing each other to regulate protective responses during infection."
Indeed, the gut contains so many nerves that it has often been called the second brain. As an alert system designed to warn the body of looming threats, the nervous system acts ultrafast. Thus, the new findings, the researchers said, suggest that evolution has taken advantage of this feature for added protection.
"If you think about it, the nervous system's involvement in immunity is an evolutionarily smart way to protect the gut from infection by repurposing an existing feature," Chiu said.
Journal Reference:
Nicole Y. Lai, Melissa A. Musser, Felipe A. Pinho-Ribeiro, Pankaj Baral, Amanda Jacobson, Pingchuan Ma, David E. Potts, Zuojia Chen, Donggi Paik, Salima Soualhi, Yiqing Yan, Aditya Misra, Kaitlin Goldstein, Valentina N. Lagomarsino, Anja Nordstrom, Kisha N. Sivanathan, Antonia Wallrapp, Vijay K. Kuchroo, Roni Nowarski, Michael N. Starnbach, Hailian Shi, Neeraj K. Surana, Dingding An, Chuan Wu, Jun R. Huh, Meenakshi Rao, Isaac M. Chiu. Gut-Innervating Nociceptor Neurons Regulate Peyer’s Patch Microfold Cells and SFB Levels to Mediate Salmonella Host Defense. Cell, 2019; DOI: 10.1016/j.cell.2019.11.014
(Score: 2) by Bot on Friday December 13 2019, @12:42PM
I knew it would happen eventually.
A mouse with integrated anti-virus.
THANK YOU WINDOWS
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(Score: 2) by Rosco P. Coltrane on Friday December 13 2019, @01:22PM
aka the brain - as in "Uuh, there's poo on that sandwich. I ain't biting on that..."
(Score: 3, Informative) by HiThere on Friday December 13 2019, @05:03PM
There have long been known to be developmental connections between the nervous system and the immune system. They probably originated from the same linage of cells. And there have been lots of previous connections between the guts, the immune system, and the brain. But this seems a bit more direct.
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