Expert interview : Pr Rémy Burcelin

Can we hope to cure metabolic diseases one day by the intestinal microbiota route?

In the 21st century, a new organ was discovered: the intestinal microbiota. This is why probiotics–which act on our flora–give us great hope. It is however too soon to consider probiotics as an independent therapy at the moment: they are likely to partially correct metabolic diseases. But firstly, patient groups with defined characteristics (biological and socioeconomic) must be isolated. Then the presence of certain bacteria as diagnostic biomarkers must be identified. And finally, extensive clinical trials must be conducted in accordance with precise objectives (lowering glycemia for example). Candidate bacteria are under consideration but for the moment none have been sufficiently effective; in particular none have shown efficacy in weight loss. But, in the current state of research, we could see probiotics arriving on the market to prevent diabetes in ten years or so.

What obstacles need to be overcome to develop an “à la carte” management of the microbiota?

The technological barriers have been eliminated thanks to real advances such as the development of effective algorithms capable of analyzing large amounts of data. The limitations are elsewhere: on the one hand, in the capacity to be able to cultivate and identically reproduce a bacterial strain (a living product, therefore perishable) once it has been identified as potentially effective; on the other hand, regulatory aspects when dealing with organisms that are liable to spread as an epidemic. For if some bacteria have proven to be harmless over the long term, others recently identified require more perspective. In any event, individual variability is not necessarily a constraint: treating just 1% of obese patients would already be a phenomenal success.

What avenues still remain to be explored in microbiota research?

Probiotics as treatment boosters. In 2017, our team showed in mice that the microbiota increases the activity of GLP-1, an intestinal hormone that is part of the therapeutic arsenal of type 2 diabetes, to which some patients are resistant. Other prospects could come from dietary fibers and polyphenols (found in grapes and pomegranates), two elements which allow positive modulation of the microbiota; or their combination with minerals, or other agents active in what is called “cobiotics”. Last avenue: aiming at a synergistic effect with synbiotics (combination of probiotics and prebiotics). These are interesting strategies to improve the tolerance and efficacy of treatments.