I am a molecular biologist whose areas of expertise include general microbiology, microbial genetics and biochemistry. In the course of my PhD studies (Paris VII University), I brought to the fore some of the molecular basis of the adaptation of the lactic acid bacterium Lactobacillus sakei to the food environment. Then, within an EU TMR fellowship in Germany (University of Erlangen-Nuremberg), I have developed an “in vivo” method for the screening of drug-RNA interactions. This work has pioneered the notion of “riboswitches” and was cited more than 150 times in top quality journals. My previous work at the IFR mainly consisted in studying a chromosomally-integrated conjugative element found in Lactococcus lactis. This work led to the publication of five articles and a patent application.

Within Simon Carding’s group at the Quadram Institute Bioscience, I am responsible for the research activity focused on deciphering the cross-talk between gut predominant commensal bacteria such as Bacteroides spp. and the host intestinal epithelium. I have identified outer membrane vesicles (OMVs) as novel mediators of these interactions. We have shown that OMVs carry molecules structurally and functionally related to those involved in mammalian cell intracellular signalling. We have also confirmed that OMVs are produced in situ in the mammalian GI-tract and that they are taken up by epithelial cells.

In fact, OMVs were rather overlooked when I started working on this project, especially the ones produced by “friendly” bacteria. It was only recently that OMVs were recognised as playing crucial roles in cell-to-cell signalling/communication (our work published in Cell Rep has been used as a key reference in several reviews).

I am also interested in studying the impact of OMVs produced by commensal bacteria not only on the host but also on other members of the microbial community of the gut. For example, I have shown that an enzyme which confers resistance to β-lactam antibiotics (cephalosporinase) associated with OMVs produced and released by Bacteroides spp. protect other commensal bacteria against these antibiotics.

Key Publications

Horn N, Carvalho A. L., Overweg K., Wegmann U., Carding S. R, Stentz. R. (2016) A Novel Tightly Regulated Gene Expression System for the Human Intestinal Symbiont Bacteroides thetaiotaomicron. Front Microbiol 7:1080.

Stentz R, Horn N, Cross K, Salt L, Brearley C, Livermore DM, Carding SR. (2015) Cephalosporinases associated with outer membrane vesicles released by Bacteroides spp. protect gut pathogens and commensals against β-lactam antibiotics. J Antimicrob Chemother 70: 701-9.

Stentz R, Osborne S, Horn N, Li AW, Hautefort I, Bongaerts R, Rouyer M, Bailey P, Shears SB, Hemmings AM, Brearley CA, Carding SR. (2014) A bacterial homolog of a eukaryotic inositol phosphate signaling enzyme mediates cross-kingdom dialog in the mammalian gut. Cell Rep 6:646-56.