P053 3-Oxo-C12:2, a quorum sensing molecule from the human gut, exerts anti-inflammatory effects through a bitter taste receptor
G. Coquant, D. Aguanno, A. Peyrottes, L. Brot, S. Thenet, J.P. Grill, L. De Sordi, P. Seksik
INSERM, Pierre and Marie Curie University, CRSA UMRS_938 Team Microbiota Intestine and Inflammation, Paris, France
Background
Acyl-homoserine lactones (AHLs) are quorum sensing molecules involved in bacterial communication network and can also have an impact on host’s cells. We recently showed the presence of AHLs in the gut ecosystem and identified one that has never been described: 3-oxo-C12:2. This molecule was decreased in faecal samples of inflammatory bowel disease (IBD) patients, especially during flare, and its absence was correlated to dysbiosis. 3-Oxo-C12:2 is structurally close to an AHL well described and synthesised by
Methods
To test our hypothesis, we used murine macrophages cell line RAW264.7, stimulated by interferon-γ (IFN-γ; 20 U/ml) and lipopolysaccharide (LPS; 10 ng/ml). Inflammatory response was monitored by measuring cytokine secretion (TFNα, IL-6 and IL-10) via ELISA. Protein expression was assessed by Western blot. Probenecid, a known allosteric inhibitor for T2R138, was used to study T2R138 role in AHL signalling. Cytotoxicity was checked by measuring LDH release.
Results
In steady state, challenged by 3-oxo-C12:2, RAW264.7 macrophages showed no change in cytokine expression (TNFα, IL-6 and IL-10). After LPS/IFN-γ activation, we observed a decrease in the ratio of secreted TNFα/IL-10 when cells are exposed to 3-oxo-C12:2, in a dose-dependent manner: 15 μM (−30%,
Conclusion
3-Oxo-C12:2 exerts a dose-dependent anti-inflammatory effect on murine immune cells. This response is partly mediated by the bitter taste receptor T2R138. This receptor is a potential target of our AHL. We are currently studying via a multiplex assay the cytokine response after exposing cells to 3-oxo-C12:2. Studying the signalling between the receptor and the anti-inflammatory response would allow us to understand better the inter-kingdom dialogue between microbiota and the host and to what extend AHLs are involved.
We are grateful for the FRM for the financial support (ECO201806006843)