How the gut protects the brain from infection


A brains sit cocooned inside a series of protective layers. They called them in injuries. And these together with a structure called the blood brain barrier keep out unwanted bugs nasties that could otherwise prove lethal forest. But how exactly the brains defense systems do. This wasn't known now. A new discovery is added an important piece to the puzzle specialized plasma cells these a blood cells that make antibodies is important potentially harmful bacteria in our intestines and then make their way up to the outer part of them in indies called the juror where they churn out antibodies and keep the brain bug free medical worthy. The thing that really got me interested in thinking about the brain is that there's increasing evidence that the immune system plays a role in a number of brain disorders so things like depression and anxiety and even the progression of neurodegenerative diseases like parkinson's disease as well as that. We know that the immune system is required to defend parts of the body from infection. So this could be important for defense against infections in the brain and in the ninja. So things like meningitis. How did you them. Pursue this to try and work out. How the brain was actually fending off infections. As with many studies in immunology we use mousers as a model and so the first thing that we did was to take meninges and look at them under the microscope and they were plasma cells in the sierra and they were not just got anywhere. They are actually lined up along. The border of large blood vessels that run through the zero. The these bug vessels are called venus. Sinuses the next question. When we find these plasma cells was empty they were producing to all surprise. We found that rather than producing igt. What's normally find in the body. They were actually producing an antibody. That's normally found gut so you've got this interesting observation an- tomic clear in the first instance of blood vessels running through. Jeez they've got cells that make antibody lining up along them. But the antibody they're making is one that you would not normally associate with the bloodstream. It's one that you would find in the testing. Yes so that was surprising. And i guess the next question was well duty cells actually originating the guts or are they influenced by the gut so to answer that we were able to use. Mice have never seen any sort of bug. They have no bacteria or any microbes in their intestine and when we looked at the dura from these animals they were no cells whatsoever but when we added bacteria back into their gut suddenly again the antibody producing cells reappeared in the era and even if we only eat put one type of bacteria into these mice a type of bacteria that couldn't go anywhere other than the gut we still saw the cells reappear in in the dearest that told us that those cells originated in the intestine. Your sort of hypothesis is the bacteria in the intestine. They educate the immune system and immune cells the intestine and what the cells then migrate from the intesting with the knowledge of how to make antibodies against those specific microbes. Up to the brain and take up residence in the meninges around the brain exactly and they specifically take up residence at the border of these d'oro venus sinuses. And i guess then the obvious question will why. Why would that happen. Why is the system being set up and the obvious answer would be. Maybe those cells there to protect The brain from microbes bacteria that originated in the gut into the bloodstream. When they're flowing through those at venus sinuses where blood flow is quite slow. It's an opportunity for the bugs to get out into the brain so to test that what we did was to remove all of the antibody producing cells and then we challenged mice with microbes into their bloodstream. And what we found was the bugs were able to get a cross into the brain as so it told us that really. We found a whole new defense system for the brain. What are you going to do next. We're interested in the signals. That might take the plasma cells from the gut to them. And jeez and then the other thing. I'm really interested in is whether this has implications for how we try and protect people from meningitis at the moment. If we vaccinated against meningitis we give that vaccine into the muscle but our study would suggest that actually if you want to make cells to defend the brain the route that you should give that vaccine is actually via the gut and so that's something that we look into the bodies a clever all thing. Isn't it minute klatt worthy there. She's basically comes university. Study describing that work has just come out in the journal nature.

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