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Benoît Chassaing, an INSERM researcher at the Cochin Institute, and his team are working on the creation of a vaccine against chronic inflammatory diseases. The early results in animals are promising.

1| An effective vaccine against inflammatory diseases

The studies conducted by Benoît Chassaing and his team concerning a vaccine capable of preventing chronic inflammatory diseases seem to be encouraging.

Early results in animals are very positive. The development of a vaccine that could modify gut microbiota composition and function in order to protect against the development of chronic inflammatory conditions such as Crohn’s disease or ulcerative colitis, has been confirmed (1).

Patients with these diseases usually have a lower than normal bacterial diversity in their intestinal flora. In addition, in these same patients there is often an excess of bacteria expressing flagellin, a protein that promotes bacterial mobility. As a result, the bacteria pass through the mucus, causing chronic inflammation. (2). Normally, mucus constitutes a sterile barrier that naturally contains antibodies, in particular anti-flagellin antibodies.

In order to increase the production of anti-flagellin antibodies in the intestinal mucosa, the researchers administered flagellin to mice. As a result, immunization against flagellin and protection against gut inflammation were observed (1).

Compared to non-vaccinated mice, vaccinated mice had a lower amount of flagellin-expressing bacteria in their microbiota and an absence of these microorganisms in their intestinal mucosa.

2| A potential vaccine strategy in humans

The presence of flagellin-expressing bacteria in the microbiota may be associated with metabolic disorders. The researchers hypothesized that there may be a correlation between excessive antibiotic use and increased food additive consumption and microbiota aggression causing metabolic diseases such as obesity and diabetes (3).

They observed that in mice given a high-fat diet, the vaccinated ones did not become obese, unlike the others. Benoît Chassaing and his team therefore demonstrated that the repeated injection of flagellin in mice triggered an increase in anti-flagellin antibodies and may reduce obesity caused by a high-fat diet.

According to the researchers, a similar vaccine strategy, with the administration of flagellin to the gut mucosa, may be possible in humans in order to prevent chronic inflammatory and metabolic diseases  (1).

3| Sources

1. Tran HQ, Ley RE, Gewirtz AT, Chassaing B. Flagellin-elicited adaptive immunity suppresses flagellated microbiota and vaccinates against chronic inflammatory diseases. Nat Commun. 10, 5650 (2019). Doi :10.1038/s41467-019-13538-y.

2. Chassaing, B. et al. Dietary emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome. Nature 519, 92–96 (2015). Doi : 10.1038/nature14232.

3. Chassaing, B. & Gewirtz, A. T. Has provoking microbiota aggression driven the obesity epidemic? Bioessays 38, 122–128 (2016). Doi : 10.1002/bies.201500116