Family, friends and colleagues contribute to the composition of our microbiome

Some of the microorganisms that make up the human microbiome are transmitted through social interaction, therefore, the people with whom we are in close contact (family, friends or colleagues) are a crucial source of bacteria that contribute to our health.

The finding -published this Wednesday in Nature- may help to understand how microbial species associated with the risk of cardiovascular disease, diabetes, cancer and other diseases are acquired.

The human microbiome is the set of microorganisms that live in our body and is essential for the proper functioning of the immune and digestive systems, among others.

However, very little is known about how we acquire and how the bacteria and other organisms that make up the microbiome are transmitted between individuals.

Nicola Segata, from the Department of Cellular, Computational and Integrative Biology (CIBIO) of the University of Trento and the European Institute of Oncology (both in Italy), has coordinated the largest international study on the transmission of bacteria associated with health.

The study has been carried out in collaboration with eighteen institutions and research centers around the world, including a research group from the Spanish Institute of Agrochemistry and Food Technology (IATACSIC).

Using more than 9,000 stool and saliva samples from people around the world, the team looked at how the bacteria are passed between generations (vertical transmission) and between people who live in close contact with each other as partners, children, or friends (vertical transmission). horizontal).

The study confirmed for the first time that the first transmission of the gut microbiome occurs at birth and is very long-lasting (maternal microbiome bacteria can be detected in older people).

The analysis also showed that adults obtain bacteria through social, person-to-person interactions, and that the oral microbiome is passed on in a markedly different way from the gut microbiome.

In fact, bacteria present in saliva are transmitted more frequently, and mainly through horizontal transmission.

Mother-to-child oral microbiome transmission is low, but the more time people spend together, the more bacteria they share.

“We have found evidence of a wide exchange of the intestinal and oral microbiome related to the type of relationship and lifestyle. The results suggest that social interactions shape the composition of our microbiomes.”says Mireia Valles-Colomer, a researcher at the Segata Laboratory and first author of the work.

“We have also found that certain bacteria, especially those that survive best outside of our bodies, are transmitted much more frequently than others.” but some are microbes that don’t even have a name, proof that very little is still known about how they are transmitted and how they affect our health, Valles-Colomer details.

The study also shows that in adulthood, the sources of our microbiomes are primarily the people with whom we come in close contact.

“The duration of interactions in students or couples sharing an apartment, for example, is roughly proportional to the number of bacteria exchanged. In many cases, however, the bacteria can spread even between individuals who have casual and superficial interactions.”Segata details.

The transmission of the microbiome has important implications for health, “since some non-communicable diseases such as cardiovascular diseases, diabetes or cancer are partially related to alterations in the microbiome”Segata says.

Demonstrating that the human microbiome is transmissible “could suggest that some of these diseases considered non-communicable could, at least to some extent, be communicable”says the researcher.

Segata proposes to carry out new studies to “to advance in the understanding of the risk factors for these diseases and, in the future, to explore the possibility of reducing the risk with therapies that act on the microbiome or its transmissible components”he concludes.

(With information from EFE)