How gut bacteria can break down cholesterol to improve cardiac health Imprimare
Sanatate
Joi, 18 Iunie 2020 11:45

                       New research has homed in on the bacterial gene responsible for metabolizing cholesterol, although the exact gut microbiome microbe doing this in humans is still unknown

                
     New research has homed in on the bacterial gene responsible for metabolizing cholesterol, although the exact gut microbiome microbe doing this in humans is still unknown

     An impressively rigorous new study, led by researchers at the Broad Institute of MIT and Harvard, is shedding light on a century-old mystery. The study describes how bacteria in the gut can metabolize cholesterol at levels high enough to improve a person’s cardiac health.

      For well over 100 years scientists have known some people seem to have an ability to metabolize cholesterol in the gut more effectively than others. A compound called coprostanol was the big clue, and the general hypothesis has been there must be a type of gut microbe that can turn cholesterol into coprostanol.


“It’s been known for a long time that some gut bacteria could form coprostanol from cholesterol, but we didn’t know which species of bacteria were doing this or how they were doing it,” explains Douglas Kenny, first author on the new study.

One of the starting points for the research came from an old study describing the discovery of microbe in a lagoon filled with hog sewage that was found to effectively metabolize cholesterol into coprostanol. So the researchers set out to sequence the entire genome of this cholesterol-consuming hog bacterium with the goal of finding out which particular enzyme is responsible for converting cholesterol into coprostanol.

 

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“Because the hog sewage lagoon microbe also formed coprostanol we decided to identify the genes responsible for this activity, hoping we might find similar genes in the human gut,” says Emily Balskus, co-senior author on the study.

At the same time, the researchers analyzed a massive human microbiome dataset to try to find particular genes that were only present in subjects excreting high volumes of coprostanol. Cross-referencing these two genetic investigations, the researchers homed in on four particular genes that were both prominent in humans with high levels of excreted coprostanol, and present in the cholesterol-consuming hog bacterium.

Engineering bacteria with each of these four genes to test which one best produced enzymes that convert cholesterol to coprostanol, the researchers eventually landed on one particular gene. They named this gene Intestinal Steroid Metabolism A (IsmA).

 

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