SCIENTISTS FINALLY DISCOVERED A DIRECT LINK BETWEEN THE BRAIN AND THE IMMUNE SYSTEM THROUGH LYMPHATIC VESSELS, THE EXISTENCE OF WHICH HAS BEEN NOT KNOWN EARLIER.
The new discovery by a group of researchers from the University of Virginia (UVA) "may require a re-evaluation of the basic pillars of neuroimmunology" (the field of study of the nervous and immune systems).
A direct link was found between the brain and the immune system through lymphatic vessels, the existence of which was not previously known. Like blood vessels that carry blood throughout the body, lymphatic vessels do the same with immune cells; however, it was long thought that such vessels were not located in the brain. New research finding lymphatic vessels under the skull of a mouse could open up avenues for understanding autism, multiple sclerosis, Alzheimer's and many other diseases.
It is becoming increasingly clear that the brain, immune system, and gut microbes are closely related. Autism, for example, is associated with gastrointestinal illness and potentially an overreaction in the immune system.
"In addition, neurological diseases such as multiple sclerosis and Alzheimer's disease have long been associated with changes in the functioning of the immune system, and autoimmune bowel diseases such as Crohn's disease have been correlated with mental illness."
It was not always clear how such connections occur, but now a gut-brain axis and a pathway from the immune system to the brain have been discovered.
They'll have to change their textbooks
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It was the reaction of Kevin Lee, Ph. D., chairman of the UVA Department of Neurology, when he heard of the find. Lymphatic vessels were found in the meninges, the protective membranes that cover the brain, and they were found to be closely associated with blood vessels.
Study lead author Jonathan Kipnis, professor of UVA neuroscience and director of the UVA Center for Brain Immunology, highlighted the importance of the discovery: “We believe these vessels may play an important role in every neurological disease with an immune component. It is difficult to imagine that they were not associated with [such] disease …
In Alzheimer's, [for example], large fragments of protein accumulate in the brain. We think this is because they cannot be effectively removed by these vessels.”
It makes sense. After all, why on earth would your brain not have a direct channel to the immune system? And all this time we were given hints. The brain was once thought to be outside the normal immune "surveillance", which was considered necessary because edema (a normal immune response) inside the brain can be fatal.
However, it would be too easy to think of the brain as “immune privileged”. According to io9:
“Careful research has shown that the brain does interact with the peripheral organs of the immune system, albeit in unique ways. Immune cells somehow circulate through the brain, and antigens that normally trigger an immune response travel from the brain to the lymph nodes.”
The newly discovered lymph vessels in the brain do indeed suggest that there is a close and significant link between the brain and the immune system, the study of which is still in its infancy.
Gut microbes also affect the brain
Not only does the immune system have a direct line with the brain. The gut, which is full of microbes, also communicates with the brain through what is called the gut-brain axis.
In fact, in addition to the brain, there is the enteric (intestinal) nervous system (ENS), which is located in the walls of the intestine and works both independently and in conjunction with it.
This communication between your two brains works in both directions, and it is because of this that food can affect your mood or because of anxiety, it can hurt your stomach. However, the gut-brain connection is much more than "comfort food" or butterflies in the stomach.
It also explains why changes in bacteria in the gut are associated with brain disease and more, including depression. Jane Foster, Ph. D., associate professor of psychiatry and behavioral neuroscience at McMaster University, described several ways gut microbes communicate with the brain in Medicine Net:
Changing gut bacteria can affect your mood
The study, published in the peer-reviewed journal Gastroenterology, involved 36 women aged 18 to 55, who were divided into three groups:
- The treatment group ate yogurt, which contains several probiotics believed to have beneficial effects on gut health, twice a day for one month
- Another group ate a "dummy" product that looked and tasted like yogurt, but did not contain probiotics
- The control group did not eat any yogurt
Before and after the four-week study, participants underwent functional magnetic resonance imaging both at rest and in the “emotion recognition challenge.” To do this, the women were shown a series of photographs of people with angry or frightened facial expressions, which they had to compare with other faces. showing the same emotions.
"This task, designed to measure the involvement of affective and cognitive regions of the brain in response to visual stimulus, was chosen because previous animal studies have linked the conversion of gut flora to changes in affective behavior," explained UCLA.
Interestingly, compared to the control group, the women who consumed probiotic yogurt had decreased activity in two brain regions that control central processing of emotions and sensations:
- The insula, which plays a role in functions commonly associated with emotion (including perception, motor skills, self-awareness, cognition, and interpersonal experience) and your body's homeostasis
- The somatosensory cortex, which is related to your body's ability to interpret a wide variety of sensations
During resting brain scans, the treatment team also showed a strong connection between an area known as the "periaqueductal gray matter" and areas of the prefrontal cortex associated with cognition. This is in contrast to the control group, which showed a greater association of gray matter with areas of the brain responsible for emotions and sensations.
"Psychobiotics" to Improve Mental Health?
There is a growing body of research showing that the brain and the microbes in your body are intricately linked. In December 2011, the journal Neurogastroenterology and Motility reported a new discovery: a probiotic known as bifidobacterium longum NCC3001 helps normalize anxiety-like behavior in mice with infectious colitis.
A separate study also found that the probiotic Lactobacillus rhamnosus has a measurable effect on the levels of GABA (an inhibitory neurotransmitter that significantly regulates physiological and psychological processes) in certain areas of the brain and reduces levels of the stress-induced hormone corticosterone, which leads to decreased behavior associated with anxiety and depression.
Neurons are present in both the brain and the gut - including neurons that produce neurotransmitters such as serotonin, which controls mood, depression, and aggression. In fact, its greatest concentration is found in the intestines, not the brain.
Psychobiotics, or “bacteria for the brain,” are even used to successfully treat depression, anxiety, and other psychiatric disorders, although more research is needed to determine which probiotics, and at what doses, are best for various mood disorders.
Researchers are currently studying so-called antibiotics - "magic bullets" that can target specific "bad" bacteria, leaving the good ones unharmed. Fecal microbiota transplants are also increasingly used as a way to achieve a healthy microbial balance.
Inflammatory connection between the gut and the brain
The gut is the starting point for inflammation - in fact, it is the watchdog for the inflammatory response. According to neuroimmunologist Kelly Brogan, microorganisms in the gut trigger the production of cytokines that are involved in regulating the immune system's response to inflammation and infection.
Like hormones, cytokines signal molecules that aid cellular communication, telling cells where to move when an inflammatory response begins. Most of the signals (about 90 percent) between the gut and the brain travel through the vagus nerve.
Vagus is Latin for “vagus,” so named because this long nerve travels from the skull down the chest and abdomen, branching into multiple organs. Cytokine messengers, produced in the intestine, travel up to the brain along the “vagus highway”.
Once inside, the cytokines "tell" your microglia (immune cells in the brain) to perform certain functions, such as producing neurochemicals. Some of them have a negative effect on your mitochondria, which can affect energy production and apoptosis (cell death), and also negatively affect the very sensitive feedback system that controls stress hormones, including cortisol.
Thus, the inflammatory response that started in the gut travels to the brain, which, based on it, then sends signals to the rest of the body through a complex feedback loop. The message is that the parts of your body are inextricably linked, and gut health is of paramount importance to your brain and immune system.
Nutritional Psychiatry for Brain Health
Returning to brain health, consuming naturally fermented foods is one of the best ways to optimize the microbiome, which in turn can optimize brain health. Fermented foods are also a key component of the GAPS protocol, a diet designed to heal and seal the intestines.
Research has shown a positive feedback loop between the food you crave and the composition of the microbiome that needs these nutrients to survive. So, if you want sugar and refined carbs, you may be feeding Candida's voracious army! When you start eliminating foods that harm the beneficial flora, start including fermented foods such as sauerkraut, naturally fermented pickles, miso, tempeh, and fermented starter cultures made from raw organic herbivorous milk (yogurt, kefir, etc.) …
This probiotic-rich food will help heal, repopulate, and “train” your gut. An article in the journal Physiological Anthropology reports that properly controlled fermentation enhances specific nutrients and phytochemicals in food, thereby improving physical, mental and brain health.
They also report that microbes associated with fermentation (such as lactobacilli and bifidobacteria) may also affect brain health in both direct and indirect ways, opening the door to new scientific research in "nutritional psychiatry."
The development of healthy intestinal microflora begins at birth. Childbirth and breastfeeding form the basis of what organisms will inhabit your baby's body. Therefore, if you are a mother-to-be, optimize your own microflora, as you will pass it on to your child.
The good news is that fermented vegetables are easy to make yourself. They are also the most economical way to add quality probiotics to your diet. Your goal is to consume a quarter to half cup of fermented vegetables with each meal, but you can gradually achieve this amount. Start with two teaspoons, several times a day, and build up depending on your tolerance.
If that's too much (your body may be heavily compromised), you might even start drinking a teaspoon of fermented vegetable pickle, which is rich in the same beneficial microbes. You may also consider taking a high potential probiotic supplement, but understand that there is no substitute for real food.
