Today is World Microbiome Day , where it is intended to inform and value the role of bacteria and the entire intestinal microbiota in maintaining health . The microbiota and its study is making an increasingly relevant niche in how we understand diseases, but also in normal physiological conditions.
The microbiome: a vast network of microorganisms
Although the concept may be simple, the microbiome is one of the most complicated concepts to study. It is made up of hundreds of thousands of different organisms , which not only vary between humans, but are also different depending on which tissue we choose.
If we want to study the interaction between a bacterium and one of our cells, we can isolate both in an artificial and controlled environment, and thus be able to eliminate other factors that may interfere. However, the reality is not so simple.
In our body, there are no isolated cells, since they all receive stimuli and information from the surrounding cells and other microorganisms . For these reasons, what is learned in artificial experiments may be very far from what happens in our body.
If we multiply this interaction by a hundred thousand, we can get a slight idea of how our body communicates with our entire microbiota. Although we do not have microbiota in all parts of our body (that we know of), the digestive tract is one of the richest in these microscopic living beings .
The stomach and its protective mechanisms
The walls of the stomach have a protective layer that is in contact with the acidic environment , which is necessary to process and digest food. Since it is an environment that destroys molecules, it can also have a damaging effect on our own cells .
For this reason, the cells of the stomach walls are in a constant state of renewal every few weeks . This process must be well regulated to ensure that cell structure and composition are maintained.
This process can be compromised if the microbiota of the digestive tract is not adequate. Specifically, an infection caused by the bacterium Helicobacter pylori has been shown to cause gastric inflammation and increase the risk of developing stomach cancer .
A bacterium that deactivates protection mechanisms
Helicobacter pylori is one of the most common causes of chronic bacterial infection, affecting half the population. In most people it can be removed, but in 15-20% of cases it can cause ulcers and cancer .
A research group from the Charité Hospital in Berlin associated with the Max Delbrück center have published a new study in the prestigious journal Nature Communications detailing the mechanism by which this bacterium modifies stomach cells.
In the stomach of a healthy person, gastric cells have a mechanism to prevent the constant renewal of cells from causing cancer. However, when an inflammation caused by the infection of this bacterium appears, this protective strategy is deactivated, which causes the cells of the stomach to divide uncontrollably and give rise to errors , which causes an increased risk of developing cancer.
In this study complex mouse models were used to study the process of gastritis on the gastric glands. The mice, after being infected with the bacteria, were analyzed to evaluate the damage of chronic inflammation in the different cells of the stomach in addition to counting the bacteria present in the organ.
Although animal models continue to be a fundamental pillar in disease research, more and more alternative techniques are being implemented. In this particular study, they used organoids to reduce the number of animals and complement the results.
Organoids are miniature representations of organs , sometimes generated from human cells from the patients themselves. This type of experiment allows artificially mimicking the conditions of an organ or tissue, and studying the effect of various treatments in a controlled environment.
In this study, mouse models and gastric organoids led the researchers to elucidate the interaction between Helicobacter pylori and a type of cell responsible for replacing other cells in the stomach. During an infection, uncontrolled proliferation gives rise to hyperplasia, a pre-cancerous lesion characterized by abnormal tissue growth.
The interaction mechanisms discovered in this study between bacteria and gastric cells open the door to new therapeutic targets for the prevention of the appearance of stomach cancer . It can even give clues about other cases in which a bacterium increases the risk of developing a pre-cancerous lesion or a microenvironment that facilitates the risk of suffering other types of cancer.
Although this study analyzes the interaction of a harmful bacteria with our body, there are many others that are essential to maintain the balance of the digestive tract and vital functions. Each study helps place a new piece in the complex puzzle of the microbiota.
References:
Kapalczynska et al. 2022. BMP feed-forward loop promotes terminal differentiation in gastric glands and is interrupted by H. pylori-driven inflammation. Nat Commun. doi: 0.1038/s41467-022-29176-w
