Researchers are looking for ways to leverage the human microbiome to make people more naturally resistant to disease, and to find genetic-based treatments and vaccines. One research team has succeeded in identifying a bacterium that can defeat cholera before the disease can activate. The implications are that there are many more to be found, each potentially capable of enhancing resistance to other diseases.
The microbiome is the collection of naturally occurring microbes (bacteria, bacteriophage, fungi, protozoa and viruses) in and on another organism. In this case, the researchers are studying the part of the microbiome in humans that reside in the gut.
“One of the surprises of the Human Genome Project was the discovery that the human genome contains only 20,000 - 25,000 protein-coding genes, about a fifth the number researchers had expected to find,” according to a post in Genome.gov.
“To search for the missing pieces that could account for this discrepancy, researchers started looking toward other sources of genetic material that contribute to human function. One of these sources was the human microbiome.”
The relationship between human and microbiome is rather bizarre and complex. Take, for example, the microbiome’s influence on your brain. It can actually affect how you think. Check out this video to see how that works:
A University of California Riverside (UCR) team, led by microbiologist Ansel Hsiao, recently discovered one bacterium in the human microbiome, called the Blautia obeum, that deactivates cholera. It produces an enzyme that blocks the signal that activates the dormant genes that cause the cholera infection.
Cholera is a deadly disease that can kill humans within hours by profound dehydration caused by intense diarrhea. It has plagued mankind since the 1800s. Every year, it strikes 1.3 million to 4.0 million people and causes up to 143,000 deaths worldwide, according to WHO.
Currently, the main treatment is to administer fluids and antibiotics. But the age of antibiotics is waning as more disease-causing bacteria becomes immune via evolution. Plus, antibiotics harm our gut microbiome and diminish its ability to help us fight and resist diseases. Antibiotics are a double-edged sword that cuts both ways, so that’s not entirely helpful.
Hsiao’s team studied the gut microbiomes of people in Bangladesh, where cholera outbreaks are prolific. “When people get sick, the diarrhea gets flushed into water systems that people drink from, and it’s a negative cycle,” Hsiao explained.
The team compared their test subjects to a group of Americans expecting the rate of infections to be explained by physical stresses such as malnutrition and poor sanitation. Instead, the researchers found “infection rates varied greatly among individuals in both populations, suggesting susceptibility is based on a person’s unique microbiome composition.”
Vibrio cholerae causes the disease known as cholera and it lives in water rather than humans, most of the time. Usually, there is no bile in water but there is in human digestion tracts. The presence of bile combined with a lack of oxygen triggers previously dormant genes in Vibrio cholerae so that it can survive in the human gut. That is how it also attaches itself to intestinal walls, rapidly colonize, and cause life-threatening diarrhea in its host.
But the researchers found that in some people, the gut microbiome has a bacterium, called Blautia obeum, which produces an enzyme that degrades salts in bile thereby destroying the signal that triggers the dormant genes in Vibrio cholerae. Viola! No cholera disease in these people.
This means that corrupting bile salts may be a quick cure for cholera. A good way to do that would be to increase the levels of that helpful bacteria in the gut.
“We are extremely interested now in learning which environmental factors, such as diet, can boost levels of obeum,” Hsiao said in a UCR article.
In light of this early discovery, results from other similar studies are eagerly anticipated.
“One day, we may also understand whether and how the microbiome affects COVID-19 and makes people resistant to other illnesses we don’t currently have treatments for,” Hsiao said.