Obesity and diabetes in humans are associated with increased rates of anxiety and depression. To understand the role of the gut microbiome and brain insulin resistance in these disorders, we evaluated behaviors and insulin action in brain of mice with diet-induced obesity (DIO) with and without antibiotic treatment. We find that DIO mice have behaviors reflective of increased anxiety and depression. This is associated with decreased insulin signaling and increased inflammation in the nucleus accumbens and amygdala. Treatment with oral metronidazole or vancomycin decreases inflammation, improves insulin signaling in the brain and reduces signs of anxiety and depression. These effects are associated with changes in the levels of tryptophan, GABA, BDNF, amino acids, and multiple acylcarnitines, and are transferable to germ-free mice by fecal transplant. Thus, changes in gut microbiota can control brain insulin signaling and metabolite levels, and this leads to altered neurobehaviors.
Author Archives: rushman
Diet Hit A Snag? Your Gut Bacteria May Be Partly To Blame
Have you ever been on a diet but didn’t hit your goal weight? Your gut bacteria may be part of the explanation.
New research suggests the mix of microbes in our guts can either help — or hinder — weight-loss efforts.
“We started with the premise that people have different microbial makeups, and this could influence how well they do with dieting,” explains Purna Kashyap, a gastroenterologist at the Mayo Clinic in Rochester, Minn.
As part of the study, Kashyap and his collaborators tracked the progress of people who were enrolled in a lifestyle-intervention program for weight loss. The participants were advised to follow a low-calorie diet, and they were tracked closely for about three months.
“We found that people who lost at least 5 percent of their body weight had a different gut bacteria as compared to those who did not lose 5 percent of their body weight,” Kashyap explains. Their findings are published in the journal Mayo Clinic Proceedings.
The successful dieters had an increased abundance of a bacteria called Phascolarctobacterium, whereas another bacteria, Dialister, was associated with a failure to lose the weight. And, Kashyap says it’s likely that there are other types of bacteria that might influence dieting as well.
So, how might bacteria influence weight loss? It turns out we can get a significant number of calories from our microbes.
Here’s how it works: Consider what happens when you eat an apple. You digest most of it.
“But there’s a certain part of the apple we can’t absorb,” explains Martin Blaser, a professor in the Department of Microbiology at NYU Langone Medical Center. “We don’t have the right enzymes to digest every bit of [the apple], but our bacteria can.”
Think of it this way: The bacteria eat what we can’t.
And, in the process, they produce byproducts that we can digest. So these byproducts become another source of calories for us.
The new study suggests that certain bacteria — or mix of bacteria — may be more efficient at creating “extra” calories for us to digest.
“Somewhere between 5 to 15 percent of all our calories come from that kind of digestion, where the microbes are providing energy for us, that we couldn’t [otherwise] get,” Blaser explains.
This calorie boost could be beneficial if food were scarce. “If times were bad, if we were starving, we’d really welcome it,” Blaser says.
But at a time when many people want to lose weight, these extra calories may be an unwanted gift.
But the study was small — just 26 participants. Now, researchers want to conduct a larger, follow-up study, including dieters from different geographic regions, to see if they can reproduce the results.
“If two studies show the same thing, then we’re on more solid ground,” Blaser says. He was not involved in the research, but agreed to review the findings for NPR. For now, he says these findings are intriguing but preliminary.
Down the road, if the results hold up in a larger group, it could lead to more tailored dieting approaches. “What we would hope to do is to be able to individualize care for people,” Kashyap says. “And we’d also try to develop new probiotics, which we could use to change the microbial makeup.”
Probiotics that are currently on the market would not be effective. The idea is to develop a new product that includes the specific types of bacteria linked to successful dieting.
But it’s not so simple to manipulate the mix of microbes in our guts. Identifying the organism — or organisms — that are thought to be beneficial is just the first step.
Next, the organisms would need to be cultivated and mass-produced in order to create a new probiotic. “Some bacteria are difficult to work with,” so it could be challenging, says Blaser.
So, if it’s possible to produce a probiotic for dieters based on this research, “it’s at least some years off,” Blaser says.
Targeting the gut microbiome to treat the osteoarthritis of obesity
Obesity is a risk factor for osteoarthritis (OA), the greatest cause of disability in the US. The impact of obesity on OA is driven by systemic in ammation, and increased systemic in ammation is now understood to be caused by gut microbiome dysbiosis. Oligofructose, a nondigestible prebiotic ber, can restore a lean gut microbial community pro le in the context of obesity, suggesting a potentially novel approach to treat the OA of obesity. Here, we report that — compared with the lean murine gut — obesity is associated with loss of bene cial Bi dobacteria, while key proin ammatory species gain in abundance. A downstream systemic in ammatory signature culminates with macrophage migration to the synovium and accelerated knee OA. Oligofructose supplementation restores the lean gut microbiome in obese mice, in part, by supporting key commensal micro ora, particularly Bi dobacterium pseudolongum. This is associated with reduced in ammation in the colon, circulation, and knee and protection from OA. This observation of a gut microbiome–OA connection sets the stage for discovery of potentially new OA therapeutics involving strategic manipulation of speci c microbial species inhabiting the intestinal space.
How Holobionts get Sick
Interesting article that continues the discussion of redeveloping our medical diagnostic and treatment paradigm to include dysbiosis. Technologies such a multiplexing assays give us the ability to quickly gauge the absence or presence of certain complexes that create an environment for disease. Additionally, the introduction of new vocabulary is essential to further discussions and analysis outside of the traditional medical paradigms.
Microbiota Transfer Therapy improves gastrointestinal and autism symptoms
Microbiota Transfer Therapy alters gut ecosystem and improves gastrointestinal and autism symptoms: an open-label study
New research suggests a link between the microbiome and autism spectrum disorder. Using a protocol that involved a fecal microbiota transplant (FMT) resulted in an improvement in both gastrointestinal symptoms but also behavioral improvements. This small study is important as it reproduces the results of other adult studies that have shown an improvement in psychological symptoms following FMT. It provides yet more evidence of a gut-brain connection and should encourage others to explore this important connection.
The Breast Has Its Own Microbiome
The Breast Has Its Own Microbiome–and the Mix of Bacteria Could Prevent or Encourage Cancer
If certain bacteria do instigate cancer, the finding could lead to new screening methods or treatments
The gut microbiome has stolen the show when it comes to the recent explosion of research on the bacteria that thrive within us. But bacteria also live in a woman’s breast tissue—and the mix of those microbes may have an equally important effect on health, according to a new study in Applied and Environmental Microbiology. The results “suggest that microbes in the breast, even in low amounts, may be playing a role in breast cancer—increasing the risk in some cases and decreasing the risk in other cases,” says Gregor Reid, a professor of microbiology and immunology at Western University in Ontario and the study’s senior author.
One in eight women in the U.S. are diagnosed with breast cancer during their lifetimes, but its origins remain unknown in most cases. Age, genetic predisposition and environmental changes are often implicated—and according to a growing body of research, bacteria may be one of those environmental factors. For instance, as early as the 1960s a number of studies have found that breast-feeding is associated with a lower risk of breast cancer, and more recent work suggests that this may be because breast milk supports the growth of beneficial microorganisms.
Link to full article –
https://www.scientificamerican.com/article/the-breast-has-its-own-microbiome-and-the-mix-of-bacteria-could-prevent-or-encourage-cancer/#
Can Bacteria Make Your Skin Healthier?
Cosmetics companies claim that tweaking the bacteria on the skin can make it healthier. But does the science stack up?
Antibacterial cosmetics are so last year; the latest craze is for face creams, serums, and washes that actually add bacteria to the skin in order to make it look younger and healthier. But experts think that these products aren’t backed up by enough science to work as their manufacturers claim.
Because they can cause disease and infection, we often think of bacteria as the enemy. But in fact, they are essential to the body’s regular function—colonies of bacteria called the microbiome live in places like the intestines, mouth, vagina, and nose, outnumbering the body’s own cells. Every person’s microbiome is unique, influenced by factors like diet, age, gender, hometown, and family.
http://www.thedailybeast.com/articles/2016/08/18/can-bacteria-make-your-skin-healthier.html
Microbes of the Skin
Human skin, the barrier between the body and the outside world, is home to diverse microorganisms, some of which can promote immunity or fight invaders.
| June 13, 2014
The microbial communities that inhabit the skin, perhaps the most diverse of the human body, are suspected to be key players in host defense. New evidence suggests that commensal skin bacteria both directly protect humans from pathogenic invaders and help the immune system maintain that delicate balance between effective protection and damaging inflammation. While causal links between the skin’s commensal microbes and health or disease remain to be demonstrated, the clues that have accumulated in the last few years paint a suggestive picture.
“None of us in the field—and this is true for the gut, this is true for the skin—none of us can actually tell how our experimental observations really relate to human disease, but we’re getting, all of us, closer to mechanistic insights,” said immunologist Yasmine Belkaid, chief of mucosal immunology at the National Institute of Allergy and Infectious Disease (NIAID).
See full article at this link –
http://www.the-scientist.com/?articles.view/articleNo/40228/title/Microbes-of-the-Skin/
Gut microbiota imbalance and colorectal cancer
Abstract
The gut microbiota acts as a real organ. The symbiotic interactions between resident micro-organisms and the digestive tract highly contribute to maintain the gut homeostasis….(continued below in the window)
Nutritional Keys for Intestinal Barrier Modulation
Abstract
The intestinal tract represents the largest interface between the external environment and the human body. Nutrient uptake mostly happens in the intestinal tract, where the epithelial surface is constantly exposed to dietary antigens. Since inflammatory response toward these antigens may be deleterious for the host, a plethora of protective mechanisms take place to avoid or attenuate local damage. For instance, the intestinal barrier is able to elicit a dynamic response that either promotes or impairs luminal antigens adhesion and crossing. Regulation of intestinal barrier is crucial to control intestinal permeability whose increase is associated with chronic inflammatory conditions. The cross talk among bacteria, immune, and dietary factors is able to modulate the mucosal barrier function, as well as the intestinal permeability. Several nutritional products have recently been proposed as regulators of the epithelial barrier, even if their effects are in part contradictory. At the same time, the metabolic function of the microbiota generates new products with different effects based on the dietary content. Besides conventional treatments, novel therapies based on complementary nutrients are now growing. Fecal therapy has been recently used for the clinical treatment of refractory Clostridium difficile infection instead of the classical antibiotic therapy. In the present review, we will outline the epithelial response to nutritional components derived from dietary intake and microbial fermentation focusing on the consequent effects on the integrity of the epithelial barrier.
Front Immunol. 2015; 6: 612.
