Our body is much more than genes. We are also thousands of bacteria living in our bodies, and their genome multiplies by a hundred the genetic material of our cells. These guests living on our skin and mucous have no free accommodation, they work for us. For example, they process all the foods we digest, assimilating them as molecules to help the metabolism of vitamins, sugars, cholesterol or bile acids.
Thanks to genomics techniques, the study of the microbiota could help to create personalized medicine. Scientists believe that by deciphering their functioning, diseases associated with alterations in our bacteria could be prevented.
To understand the microbiota, we must first get rid of old prejudices. Their image is associated with pathogens or germs from the nineteenth century, when researchers identified some microorganisms as carriers of infectious diseases. Decades later, the microbiota came to be considered as an unnecessary burden of bugs inside ourselves.
“In medical schools in the seventies, bacteria were understood as some commensals that took advantage of us or as dirty, but which did not bothered,” remembers Francisco Guarner, section chief of gastroenterology service of the Hospital Vall d’Hebron of Barcelona.
Experiments with animals completely free of bacteria or germ-free, marked a turning point in the late twentieth century when showed that the absence of microbiota resulted in problems in growth, immune and endocrine systems and brain and gastrointestinal tract functions. “We understood that being free of bacteria is worse. Because with the food we eat, they produce substances that serve as nutrients,” says Guarner.
“With new techniques, we have suddenly discovered a variety of microorganisms we did not know, so we must reconsider all the axioms so far established. For example, we could not suspect that the dermis had so much bacterial variety, so that there are more differences between the skin behind the ear and groin, than between the microbiomes at the Sahara Desert and the North Pole, “said Daniel Ramon, scientific director of the biotechnology company Biopolis, Valencia.
The intestine as a second brain
In 2013, researchers at Washington University School of Medicine showed that bacteria that live in the body can pass a phenotype (particular traits inherited). They transplanted fecal microbiota from adult human twin pairs discordant for obesity into germ-free mice. The researchers found that mice harboring an obese twin’s microbiota fattened in comparison with lean twin’s microbiota, reveling transmissible, rapid and modifiable effects of diet-by-microbiota interactions.
When worries and stress attack our lives, our digestion suffers the consequences. The explanation lies in the relationship between our nervous system and the gastrointestinal tract. Psychological stress can alter gastrointestinal functions.
However, this relationship operates bi-directionally; microbiota in our gut, sometimes referred to as the “second brain,” may influence our mood in ways that scientists are just now beginning to understand. Digestive sensations can affect emotions and behavior, as a meal makes you feel in a good mood.
It’s estimated that there are between 400 and 600 million neurons in your gut – that’s up to three times as many neurons than in the brain of a rat. You’re not conscious of your gut thinking, but the system produces about 95% of the serotonin and 50% of the dopamine found in your body.
In the past, certain behaviors were linked to specific species. A research at McMaster University in Hamilton, Canada, has shown that behavior also depends on the bacteria living in each species. The study measured the time two different strains of mice took to decide jumping from a platform. The quick strain took on average 20 seconds to jump, while the slow one took several minutes. The scientists transplanted intestinal microbiota from the fast mice strain to slow one, which increased their speed.
Antibiotics and extreme cleanliness, the enemy of our microbiota
Who has not felt a low energy after taking antibiotics? This is due to the antibacterial action of the drug, which not only eliminate pathogens but also a great number of friendly bacteria in our body. The good news is that after that metabolic depression, microbiota can recover by itself.
“We think there are reservoirs in areas such as the ileum, near the appendix, restoring the microbiota. But we still do not know how much there are involved the internal microbiota and external one we receive in our diet, “says Andres Moya, Professor of Genetics at the University of Valencia and researcher at the Joint Research Unit on Genomics and Health of the Foundation for the Development of Biomedical and Health Research of Valencia (FISABIO).
In addition to the consumption of antibiotics, bacterial diversity loss is linked to the increasingly occurrence of allergies, resulting from excessive hygiene. In Sweden, a study analyzed the environmental factors that influence childhood allergies to birch pollen. Researchers at the Pediatric Allergology & Pulmonology at Queen Silvia Children’s Hospital found a higher risk of children suffering from allergies in homes where there is dishwasher. This is caused by water temperature in the dishwasher: 65 degrees Celsius in comparison with 30 degrees of the sink water; which eliminates microbial diversity.
Other study conducted by German researchers found babies born via C-section were twice as likely to be sensitive to common foods, such as cows’ milk, at 12 months of age as babies born vaginally. C-section babies were also more likely to have diarrhea during their first year of life. The researchers explained that the findings agree with previous research that has demonstrated the importance of bacteria in the gut in the development of a healthy immune system. Operation rooms are commonly more sterilized than common delivery rooms and by bypassing the vaginal birth canal, researchers say that caesarean sections alter or delay normal bacterial development in the baby’s gut.
“It has been also shown that children who eat live bacteria thanks to yogurt, sauerkraut or fermented cucumber teach better their immune system to avoid the error of identifying pollen as an enemy, the mechanism by which allergy occurs,” said Guarner, Spanish coordinator of the International Human Microbiome Project, an international consortium that has the challenge of analyzing a catalog of over 10 million genes in the human intestine, from America, China and Europe.
One of the ecosystems where they can best observe the close relationship between environmental factors and the balance of the microbiota is the female genital organ. The acidity of the vagina becomes harsh terrain for pathogens. However, intimate douches and soaps neutralize its pH eliminating colonies of lactobacilli, bacterial shield against the invasion of undesirable microorganisms.
The knowledge scientists are acquiring about our microbiota may be the basis of personalized therapies by basing treatments on the known metabolic tendencies of a person’s microbiota category.
Source: Agencia ID
