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A gut bacterium as a fountain of youth? Well, let’s start with reversing insulin resistance - Orlando Sentinel

But insulin resistance is also linked to a rogue’s gallery of ills, from obesity and inflammation to the sagging immunity and frailty that comes with advancing age. If a readily available means of slowing or reversing insulin resistance could be identified, it might have broad and powerful anti-aging effects (in addition to protecting some of the world’s 650 million adults who are obese against developing type 2 diabetes). First identified in 2004, Akkermansia muciniphila inhabits the large intestine and is thought to account for between 1% and 5% of all intestinal bacteria in adults. Scientists suspect it helps preserve the coat of mucus that lines the walls of our intestines. It may also play a role in making the polyphenols we eat in plant-based foods more available to our cells. Evidence is mounting that A. muciniphila is involved in obesity, glucose metabolism and intestinal immunity. For instance, a 2018 study of cancer patients suggests that it plays a role in immune response. Compared to patients who failed to be helped by a new generation of immunotherapy, those who did had a greater abundance of Akkermansia in their guts. When researchers took the stool of a patient who responded positively to the cancer-fighting therapy and transplanted it into lab animals with human cancers, the recipients became more likely to respond positively to the same treatment. In the new research, a team from the National Institute on Aging examined the molecular chain of events that appears to result from A. muciniphila’s depletion in mice and macaque monkeys. And they assessed the effects of restoring this gut microbe to elderly animals. First, they documented that the guts of older animals had markedly smaller populations of A. muciniphila than the guts of young animals, and that as A. muciniphila became more scarce, so did butyrate, one of the gut’s key protectors. The deficiency of these two substances caused the mucous walls of the of the aged animals’ intestines to thin and grow leaky. That corrosive process unleashed a chain of events that touched off inflammation, prompted an immune response and, in a final step, increased insulin resistance. Key to that final step was the accumulation in the gut of a specific kind of immune cell called 4BL cells. If the detrimental chain of events was to be disrupted, the accumulation of those 4BL cells probably had to be stopped, the researchers surmised. The researchers also documented what appeared to be a role for A. muciniphila in fostering healthy diversity among the garden of other microbes that colonize the gut. In animals with scant populations of A. muciniphila, a host of other common gut bacteria — as well as their beneficial byproducts, particularly butyrate — also suffered.

Gut bacteria may control movement: Study suggests that bacteria may regulate neuronal circuits behind movement in flies -- ScienceDaily

observed that germ-free flies, which did not carry bacteria, were hyperactive. For instance, they walked faster, over greater distances, and took shorter rests than flies that had normal levels of microbes. Dr. Mazmanian and his team investigated ways in which gut bacteria may affect behavior in fruit flies. "Locomotion is important for a number of activities such as mating and searching for food. It turns out that gut bacteria may be critical for fundamental behaviors in animals," said Dr. Mazmanian. Fruit flies carry between five and 20 different species of bacteria and Dr. Mazmanian's team treated the germ-free animals with individual strains of those microbes. When the flies received Lactobacillus brevis, their movements slowed down to normal speed. L. brevis was one of only two species of bacteria that restored normal behavior in the germ-free flies. Dr. Mazmanian's group also discovered that the molecule xylose isomerase (Xi), a protein that breaks down sugar and is found in L. brevis, may be critical to this process. Isolating the molecule and treating germ-free flies with it was sufficient to slow down the speedwalkers.

Microbiome test

It’s based on more than five years of highly cited research at Israel’s Weizmann Institute, showing, for example, that while people on average respond similarly to white bread versus whole grain sourdough bread, the differences between individuals can be huge: what’s good for one specific person may be bad for another.

Scientists reveal how gut microbes 'recover' after antibiotic treatment -- ScienceDaily

We also saw that as antibiotics removed bacteria and reduced their metabolic rates in the mouse gut, there was an increase in oxidising agents called electron acceptors," Reese explains. "This new environmental state meant that the microbial community which recolonised after treatment looked very different from the original community." The bacteria that appeared immediately following treatment, including some potentially harmful species, were able to take advantage of the electron acceptors to grow quickly. As they grew, they used up the excess resources, causing the gut environment to return to its normal state. However, this did not guarantee recovery of the original microbial community. "Antibiotics may drive some microbe species extinct in a gut community, so new microbial immigrants from outside the mouse -- in this case from an untreated mouse in the same cage -- were likely needed to return the microbiota to its original state," says senior author Lawrence David, Assistant Professor of Molecular Genetics and Microbiology at Duke University.

Early source of irritable bowel syndrome discovered -- ScienceDaily

"The gut has its own brain and that has more neurons in the intestines than in the spinal cord. Within your intestines lies a 'second brain' called the enteric nervous system," said Brian Gulbransen, MSU neuroscientist and the study's senior author. "The enteric nervous system is an exceedingly complex network of neural circuits that programs a diverse array of gut patterns and is responsible for controlling most gastrointestinal functions." Accompanying the neurons in this second brain are enteric glia, which are responsible for regulating inflammation. The disruption of neural circuits in the gut by inflammation is considered an important factor in the development of irritable bowel syndrome and inflammatory bowel disease.

A gut bacterium's guide to building a microbiome: Unlike invading pathogens, which are attacked by the immune system, certain good bacteria in the gut invite an immune response in order to establish robust gut colonization -- ScienceDaily

The particular species is found abundantly in the large intestines of many mammals, including humans, and was previously shown by the Mazmanian lab to protect mice from certain inflammatory and neurological disorders such as inflammatory bowel disease and multiple sclerosis. Interestingly, though there are multiple strains of B. fragilis, healthy people form a long-term, monogamous relationship with only a single strain. "Studies by other labs have shown that most people carry the same strain of B. fragilis throughout their lives," says Donaldson. "We wanted to understand at a molecular level how these bacteria are able to colonize the gut in a stable, long-term way." First, the researchers aimed to examine B. fragilis's symbiotic relationship with the gut by physically looking at the locations where the bacteria reside. Using electron microscopy imaging on samples of mouse intestines, the team was able to see that B. fragilis clumps together in aggregates deep within the thick layer of mucus lining the gut, nestled close to the epithelial cells that line the surface of the intestine. Donaldson and his collaborators theorized that this spatial niche is necessary for a single species to settle in and establish a stable foothold. The team next aimed to determine what mechanisms allow B. fragilis to colonize such a niche within the gut. They found that each B. fragilis bacterium is encased in a thick capsule made of carbohydrates. The capsule is typically associated with pathogens (bad bacteria) attempting to cloak themselves from recognition by and attack from the body's immune system. Mutant bacteria lacking this capsule cannot aggregate and do not inhabit the mucosal layer. Thus, the researchers theorized that capsular carbohydrates are necessary for B. fragilis strains to monopolize their niche in the gut. Because bacterial capsules were known to be related to an immune response in pathogenic bacteria, Donaldson and Mazmanian hypothesized that there may also be an immune response to the B. fragilis capsule. Indeed, they found that antibodies, immune proteins that grab onto and mark specific bacteria or viruses for other immune cells to engulf and destroy, were binding to the B. fragilis capsule in the intestine. One particular kind of antibody, immunoglobulin A or IgA, is found throughout the gut -- in fact, it is the most abundantly produced type of antibody in humans -- but its specific functions have been enigmatic.

Traumatic brain injury causes intestinal damage, study shows: Two-way brain-gut interactions may worsen outcome after TBI -- ScienceDaily

This is the first study to find that TBI in mice can trigger delayed, long-term changes in the colon and that subsequent bacterial infections in the gastrointestinal system can increase posttraumatic brain inflammation and associated tissue loss. The findings were published recently in the journal Brain, Behavior, and Immunity. "These results indicate strong two-way interactions between the brain and the gut that may help explain the increased incidence of systemic infections after brain trauma and allow new treatment approaches," said the lead researcher, Alan Faden, MD, the David S. Brown Professor in Trauma in the Departments of Anesthesiology, Anatomy & Neurobiology, Psychiatry, Neurology, and Neurosurgery at UMSOM, and director of the UMSOM Shock, Trauma and Anesthesiology Research Center.

Antibiotics found to weaken body's ability to fight off disease -- ScienceDaily

"Neutrophils play an important role as a first-line 'innate immune response' when foreign pathogens invade," said researcher Koji Watanabe, PhD. "We found that antibiotic disruption of the natural microbes in the gut prevented this from happening properly, leaving the gut susceptible to severe infection."

How gut bacteria ensure a healthy brain – and could play a role in treating depression

Some gut bacteria can even alter neurotransmitter levels directly by converting glutamate – an excitatory transmitter – into GABA – an inhibitory brain chemical. And gut microbes, along with neighbouring intestinal cells, communicate with a branch of the nervous system called the enteric nervous system (ENS) whose neurons surround the entire gastrointestinal tract. This part of the nervous system is so sophisticated that many refer to it as the body’s second brain.