3-oxo-C12:2-HSL, Quorum Sensing Molecule from Human Intestinal Microbiota, Inhibits Pro-inflammatory Pathways in Immune Cells via Bitter Taste Receptors

Abstract In the gut ecosystem, microorganisms regulate group behaviour and interplay with the host via a molecular system called quorum sensing (QS). The QS molecule 3-oxo-C12:2-HSL, first identified in human gut microbiota, exerts anti-inflammatory effects and could play a role in inflammatory bowel diseases where dysbiosis has been described. Our aim was to identify which signalling pathways are involved in this effect. We observed that 3-oxo-C12:2-HSL decreases expression of pro-inflammatory cytokines such as, Interleukine-1β (-3 %) and Tumor Necrosis Factor-α (TNFα) (40 %) by stimulated immune RAW264.7 cells and decreased TNF secretion by stimulated PBMC in a dose-dependent manner, between 25 µM to 100 µM. Transcriptomic analysis of RAW264.7 cells exposed to 3-oxo-C12:2-HSL, in a pro-inflammatory context, highlighted JAK-STAT, NF-κB and TFN signalling pathways and we confirmed that 3-oxo-C12:2-HSL inhibited JAK1 and STAT1 phosphorylation. We also showed through a screening assay that 3-oxo-C12:2-HSL interacted with several human bitter taste receptors. Its anti-inflammatory effect involved TAS2R38 as shown by pharmacologic inhibition and led to an increase in intracellular calcium levels. We thus unravelled the involvement of several cellular pathways in the anti-inflammatory effects exerted by the QS molecule 3-oxo-C12:2-HSL.

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Bitter Taste Receptors, T2R138 and T2R16, are Induced in the Large Intestine of Male and Female Mice on a High Fat Diet in a Microbiota-Dependent Manner

Gastroenterology ◽

10.1016/s0016-5085(17)30846-6 ◽

2017 ◽

Vol 152 (5) ◽

pp. S156

Author(s):

Filippo Caremoli ◽

Jennifer Huynh ◽

Venu Lagishetty ◽

Jonathan Jacobs ◽

Jonathan Braun ◽

...

Keyword(s):

Large Intestine ◽

High Fat Diet ◽

Bitter Taste ◽

Taste Receptors ◽

Dependent Manner ◽

High Fat ◽

Male And Female ◽

Female Mice ◽

Bitter Taste Receptors

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P064 3-oxo-C12:2, a Quorum Sensing molecule from the gut, exerts anti-inflammatory effects through a bitter taste receptor

Journal of Crohn s and Colitis ◽

10.1093/ecco-jcc/jjab076.193 ◽

2021 ◽

Vol 15 (Supplement_1) ◽

pp. S169-S170

Author(s):

G Coquant ◽

D Aguanno ◽

A Peyrottes ◽

L Brot ◽

C Belloir ◽

...

Keyword(s):

Quorum Sensing ◽

Inflammatory Response ◽

Bitter Taste ◽

Taste Receptor ◽

Bitter Taste Receptor ◽

Screening Assay ◽

Inflammatory Pathways ◽

Anti Inflammatory ◽

Dose Dependent ◽

Inflammatory Effect

Abstract Background Acyl-Homoserine Lactones (AHLs) are Quorum Sensing molecules involved in the communication network of bacteria and can also have an impact on the host’s cells. We recently showed, in the gut ecosystems, the presence AHLs and among them we identified one that has never been described: 3-oxo-C12:2. This molecule was decreased in Inflammatory Bowel Disease (IBD) patients, especially during flare, and its presence was correlated to normobiosis. Interestingly, 3-oxo-C12:2 is structurally close to an AHL well described and synthesized by P. aeruginosa, 3-oxo-C12. We intent to describe 3-oxo-C12:2 effects on gut inflammation and to identified which signalling pathways are involved. Given its analogous structure to 3-oxo-C12, we hypothesized that 3-oxo-C12:2 can interact with the same cellular partners, in particular a bitter taste receptor (BTR), called T2R138, which is a GPCR expressed by immune and epithelial gut cells. Methods To test our hypothesis, we used murine macrophages cell line RAW264.7, stimulated by interferon-ɣ (IFN-g, 20U/mL) and lipopolysaccharide (LPS, 10ng/mL). We performed a transcriptome analysis using RNAseq to identify inflammatory pathways involved in the effects. Inflammatory response was monitored by measuring cytokine secretion TFNα via ELISA. Probenecid, a known allosteric inhibitor for T2R138, was used to study T2R138 role in AHL signalling. BTR screening assay was performed to extend search for 3-oxo-C12:2 receptors. Cytotoxicity was measured via Lactate Dehydrogenase release. Results After LPS/IFN-γ activation, we observed a decrease of secreted TNFα when cells are exposed to 3-oxo-C12:2, in a dose dependent manner: 15μM (-30%, p<0.05), 25μM (-50%, p<0.001) et 50μM (-65%, p<0.0001), no change were observed in steady state. Itreflects an anti-inflammatory effect, without increasing cytotoxicity. To identify mechanisms behind those effects, we analysed the transcriptome of RAW264.7 cells exposed to AHL. JAK-STAT and NF-κB pathways were differentially down-regulated in presence of 3-oxo-C12:2. In addition, the anti-inflammatory effects were lost in presence of Probenecid, a T2R138 inhibitor. In a BTR screening assay, we confirmed that 3-oxo-C12:2 activates T2R38, but also five other BTR (T2R13, T2R8, T2R14, T2R1, T2R10). 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 of interest and we are currently studying the inflammatory pathways involved behind those effects. Studying the signalling between the receptor and the anti-inflammatory response would allow us to better understand the inter-kingdom dialogue between microbiota involving AHL in IBD.

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Nitric Oxide Production is Stimulated by Bitter Taste Receptors Ubiquitously Expressed in the Sinonasal Cavity

American Journal of Rhinology and Allergy ◽

10.2500/ajra.2017.31.4424 ◽

2017 ◽

Vol 31 (2) ◽

pp. 85-92 ◽

Cited By ~ 29

Author(s):

Carol H. Yan ◽

Samuel Hahn ◽

Derek McMahon ◽

David Bonislawski ◽

David W. Kennedy ◽

...

Keyword(s):

Nitric Oxide ◽

Bitter Taste ◽

Middle Turbinate ◽

Immune Defense ◽

Sinus Surgery ◽

No Production ◽

Taste Receptors ◽

Dependent Manner ◽

Innate Defense ◽

Bitter Taste Receptors

Background Bitter taste receptors (T2R) have recently been demonstrated to contribute to sinonasal innate immunity. One T2R, T2R38, regulates mucosal defense against gram-negative organisms through nitric oxide (NO) production, which enhances mucociliary clearance and directly kills bacteria. To determine whether additional T2Rs contribute to this innate defense, we evaluated two other sinonasal T2Rs (T2R4 and T2R16) for regulation of NO production and expression within the human sinonasal cavity. Methods Primary human sinonasal cultures were stimulated with ligands specific to T2R4 and T2R16, colchicine and D-salicin, respectively. Cellular NO production was measured by intracellular 4-amino-5-methylamino-2’, 7′-difluorofluorescein diacetate fluorescence. For T2R expression mapping, sinonasal tissue was obtained from patients who underwent sinus surgery of the middle turbinate, maxillary sinus, ethmoid sinus, or sphenoid sinus. The expression of T2R4, T2R16, and T2R38 was evaluated by using immunofluorescence with validated antibodies. Results Similar to T2R38, T2R4 and T2R16 trigger NO production in a dose-dependent manner by using the canonical taste signaling pathway in response to stimulation with their respective ligands. All three receptors were expressed in the cilia of human epithelial cells of all regions in the sinonasal cavity. Conclusion These three T2Rs signaled through the same NO-mediated antimicrobial pathway and were ubiquitously expressed in the sinonasal epithelium. Additional T2Rs besides T2R38 may play a role in sinonasal immune defense. Mapping of T2R expression demonstrated the potential widespread role of T2Rs in sinonasal defense, whereas the genetics of these T2Rs may contribute to our understanding of specific endotypes of chronic rhinosinusitis and develop into novel therapeutic targets.

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