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Gut microbioma regulates the immune system in the intestinal tract – ScienceDaily

The scientist has long known that bacteria in the intestines, also known as the microbial, perform a host of useful functions for their hosts, such as breaking down dietary fiber in the digestive process and making vitamins K and B7. Yet another study reveals another useful role the microbiology plays. A team of researchers from Brown University found that in mice the intestinal microbiology regulates the host's immune system – so that the bacteria in combination with the immune system can cooperate in peace with the immune system, rather than the host's defense that attacks these useful bacteria. What is the trick against the microbiology's work with the immune system? Vitamin A &#8211 ; The bacteria moderate active A levels in the intestines, protecting the microbiome from an overactive immune response. This insight may be important for understanding and treating autoimmune and inflammatory diseases, "said Shipra Vaishnava, a deputy professor of molecular microbiology and immunology at Brown. "Many of these diseases are attributable to increased immune response or immune activation, but we have found a new way that bacteria in our intestine can suppress the immune response," said Vaishnava. "This research may be crucial for determining therapies in autoimmune diseases such as Crohns disease or other inflammatory bowel disease as well as vitamin A deficiency. " The study was published on Tuesday, December 18th in the newspaper Immunity . Microbiomics of Mice and Men The intestinal microbioma is an ecosystem made of 100 trillion bacteria that has been developed to…

The scientist has long known that bacteria in the intestines, also known as the microbial, perform a host of useful functions for their hosts, such as breaking down dietary fiber in the digestive process and making vitamins K and B7.

Yet another study reveals another useful role the microbiology plays. A team of researchers from Brown University found that in mice the intestinal microbiology regulates the host’s immune system – so that the bacteria in combination with the immune system can cooperate in peace with the immune system, rather than the host’s defense that attacks these useful bacteria.

What is the trick against the microbiology’s work with the immune system? Vitamin A &#8211

; The bacteria moderate active A levels in the intestines, protecting the microbiome from an overactive immune response.

This insight may be important for understanding and treating autoimmune and inflammatory diseases, “said Shipra Vaishnava, a deputy professor of molecular microbiology and immunology at Brown.

“Many of these diseases are attributable to increased immune response or immune activation, but we have found a new way that bacteria in our intestine can suppress the immune response,” said Vaishnava. “This research may be crucial for determining therapies in autoimmune diseases such as Crohns disease or other inflammatory bowel disease as well as vitamin A deficiency. “

The study was published on Tuesday, December 18th in the newspaper Immunity .

Microbiomics of Mice and Men

The intestinal microbioma is an ecosystem made of 100 trillion bacteria that has been developed to live under the particular conditions of the intestines Vaishnava said. Most of these bacteria do not damage their hosts but are helpful instead. A healthy microbiome, like a healthy forest, has many species that exist together and can ward off hostile intruders – as disease-causing bacteria or invasive species .

In both humans and mice, phyla Firmicutes and Bacteroidetes include the majority of the intestinal microbial community. In order to be able to play its role in regulating their host’s immune system, the bacteria in the microbiome determine the levels of a protein responsible for the conversion of vitamin A to its active form in their host’s gastrointestinal tract.

Vaishnava’s team found that Firmicutes bacteria, especially members of the class Clostridia, reduce the expression of a protein in the cells that lead the intestines. The protein, retinol dehydrogenase 7 (Rdh7) converts dietary vitamin A into its active form, retinoic acid, Vaishnava said. Clostridia bacteria, common to both mice and men, also promote increased vitamin A stock in the liver, found the team.

Vaishnava expects the results to be generalizable for the interactions between the human microbiome and their hosts as well.

Mice genetically engineered to not have Rdh7 in their intestinal cells have less retinoic acid in the intestinal tract, as scientists expected. Specifically, the manipulated mice had fewer immune cells that make IL-22 an important cellular signal that coordinates the antimicrobial response to intestinal bacteria. Other components of the immune system, such as immunoglobulin A cells and two types of T cells, were the same as in common mice, indicating that Rdh7 is only necessary for the regulated antimicrobial response, Vaishnava says.

Scientists do not know exactly how Rdh7 is suppressed, but Clostridia bacteria are known to produce short-chain fatty acids that change hostile expressions. As a next step in its research, the team will study how bacteria regulate Rdh7 expression, among other things by examining various short-chain fatty acids, Vaishnava says.

In addition, the team will conduct research to understand why Rdh7 suppression is critical. They work to genetically manipulate mice to always express Rdh7 in their intestinal cells. Vaishnava wants to see how this affects the mouse microbioma and if it leads to inflammation or autoimmune disease for the mice. They will also investigate the effects of increased vitamin A storage in the liver due to bacteria Rdh7 regulation, says Vaishnava.

Helping People’s Health

The researchers say understanding how bacteria regulate the immune system’s response can be important to unlock the keys to disorders such as Crohn’s disease.

Data from clinical trials have shown that inflammation of the intestine is a result of interfering interactions between a host and their intestinal microbial, said Vaishnava.

“The role of vitamin A in inflammation is context-dependent and is very difficult to erase,” Vaishnava said. “A change of vitamin A status and vitamin A metabolic genes coincide with inflammatory bowel disease, but we do not know if this promotes inflammation or not. We hope we add our results – that bacteria can regulate how vitamin A is metabolized in the intestines or stored – can help clarify why the field sees what it sees. “

These results can also provide clues about the importance of microbiomics to address vitamin A deficiency, a problem commonly found in Africa and Southeast Asia.

Vitamin A deficiency affects approximately one third of children under five years, according to the World Health Organization (WHO). Vitamin A deficiency degrades the immune system and increases the risk of infectious diseases. WHO has provided risky children with vitamin A supplements in the last 25 years, but it has not been as successful as hoped, according to Vaishnava. This study shows bacteria is a major part of A absorption and storage, and maybe children must have the right combination of bacteria in the intestine to ensure that vitamin A supplements are most effective, she added.

“Both our diet and the bacteria in our intestines are critically linked to regulating how our immune cells behave,” says Vaishnava. “Finding what these links are at the molecular level is important to figure out how to use either diet or bacteria, or both together, to have a therapeutic effect in inflammatory or infectious diseases. “

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