Intestines: a lead in Crohn’s disease
The study of the microbiota made it possible to identify certain anomalies linked to chronic inflammatory pathologies of the digestive tract, in particular Crohn’s disease and ulcerative colitis.
The flora of patients who suffer from it contains 30% of “extremely rare” bacteria. In Crohn’s disease, there has also been a change in the ratio between two species: Firmicutes (a family which includes clostridium, bacillus, lactobacillus, etc.) and Bacteroidetes (a group made up of bacteroides and flavobacteria, in particular).
While the normal adult flora harbors about ten Firmicutes for a Bacteroidete, the former are ten times less numerous in those
who suffer from Crohn’s disease.
The particularly low amount of one species of Firmicutes – a bacterium called Faecalibacterium prausnitzii – could be particularly responsible for the disorders. It is proven, in fact, that it secretes molecules with important anti-inflammatory properties. “The analysis of the microbiota of patients could confirm the diagnosis of these diseases, and even come to refine it, advances Joël Doré. In patients who had just removed part of the intestine, it has been observed that the risk of early recurrence is all the more important as their level of Faecalibacterium prausnitzii
is low. In contrast, the presence of another species of bacteria, called Calibacterium prognitia, seems to protect against recurrence. “
Intestines: prospects for relieving irritable bowels
Many mysteries surround this inner world of which we hear only the gurgling but which, however, dialogues with us constantly. To know how to best use these microorganisms, it is necessary to understand their precise role, in particular the interactions between their genes and ours, which promote or inhibit certain functions. They could then make it possible to fight against diseases of immune origin or to soothe irritable bowel syndrome, in which there are also flora abnormalities. “But we do not know how the bacteria interact with the cells of the intestinal mucosa or the immune cells of the blood, located just below, admits Joël Doré.
And we discover interactions with organs that go beyond the intestine. If it is well known, for example, that fear or anxiety can make you “stomach ache”, the Canadian Stephen Collins has shown that the intestine can also act on the brain! He switched the flora of two lines of mice, one calm, the other anxious, and found that their behavior was immediately reversed, as evidenced by changes in neurotransmitters in the brain. “
Intestines: a new approach to fight obesity
As in Crohn’s disease, the relationship between Firmicutes bacteria and Bacteroidetes is imbalanced in obese people. But in reverse: in their flora, we find a hundred Firmicutes (ten times more than the normal value) for a Bacteroidete. It seems more and more obvious that this deficit in Bacteroidetes favors the storage of fats. This was verified by transferring the intestinal flora from an obese mouse to a thin mouse.
And by noting that the latter immediately began to grow excessively, as if his body was becoming more efficient in recovering energy. The Inserm / UPCM team at the Pitié-Salpêtrière hospital (Paris), for its part, observed that the flora was modified in obese people who lost a lot of weight after the installation of a gastric bypass (intervention which short-circuits part of the stomach). Whether it is the cause or the consequence of the problem, the flora contributes to perpetuate and worsen the situation. Could we transform it to promote weight loss? And would that limit the dangers of overweight? Many researchers are working on these questions …
Intestines: a hope in the prevention and treatment of diabetes
Researchers from Inra and Inserm have studied the role of intestinal bacteria in diseases associated with obesity. And they have recently been shown to be involved in the development of fatty liver disease (accumulation of fat in the liver) and diabetes. To do this, they transplanted
in mice “virgin” of any microbiota, sometimes the flora of a mouse exhibiting insulin resistance (prediabetes) and hepatic steatosis, sometimes that of a healthy mouse. “The two groups being fed for four months with a hyperlipidic diet (rich in fat), all the animals became obese, explains Karine Clément, head of the study. But only the mice in the first group became diabetic, and their liver condition deteriorated more seriously. ”
A new way to prevent the onset of type 2 diabetes or help stop it? We could hope so… “Researchers in the Netherlands have instilled the flora of non-diabetics in people suffering from diabetes, previously cleaned of their flora by colonic preparation (the same as for a colonoscopy), confirms Karine Clément. After six weeks, an improvement was noticed. “
