To look at what we are from another point of view and express the weight of the microorganisms that inhabit us, an effective trick is to imagine man as a huge colony of cells. In this representation, some members of the colony are human cells, specialized in it or in it, and many are bacteria, which cooperate or compete with each other within the envelope that is the human body. The image is rounded by a data related to DNA: the sequenced human genome is only 10% of body DNA, the rest is microorganisms.
The protagonists of this issue are some of these microorganisms, specifically the bacteria that inhabit our intestine. To say that they are essential for the performance of certain functions related to digestion is not new now. And they can be responsible for certain diseases. However, research in recent years has shown that they have many more functions and have led to a profound change in our vision of intestinal bacteria.
Research has shown its involvement not only in metabolism, but also in many other aspects such as immunology and neurology. The relationship between intestinal bacteria and our body is so close that organ consideration is an increasingly widespread view. This is recognized, among others, by the immunogenetic researcher of the UPV/EHU, José Ramón Bilbao.
Throughout the ten pages of this issue we have compiled the testimony of this shift in focus and tell how intestinal bacteria have gone from being “enemy” to “necessary rescuers” in some cases to being “weak”; “organs”. All the arguments that make up the testimony are not easy to digest in the first reading, and some are slow reading. For example, the path that can go from intestinal bacteria to autism is not done right away. However, the reasons for thinking that the intervention they have in us can be of that nature are not exclusive.