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Latorre E, Layunta E, Grasa L, Castro M, Pardo J, Gomollón F, Alcalde AI, Mesonero JE. Intestinal Serotonin Transporter Inhibition by Toll-Like Receptor 2 Activation. A Feedback Modulation. PLoS One 2016; 11:e0169303. [PMID: 28033388 PMCID: PMC5199115 DOI: 10.1371/journal.pone.0169303] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Accepted: 12/14/2016] [Indexed: 01/09/2023] Open
Abstract
TLR2 is a microbiota recognition receptor that has been described to contribute to intestinal homeostasis and to ameliorate inflammatory intestinal injury. In this context, serotonin (5-HT) has shown to be an essential intestinal physiological neuromodulator that is also involved in intestinal inflammatory diseases. Since the interaction between TLR2 activation and the intestinal serotoninergic system remains non-investigated, our main aim was to analyze the effect of TLR2 on intestinal serotonin transporter (SERT) activity and expression and the intracellular pathways involved. Caco-2/TC7 cells were used to analyze SERT and TLR2 molecular expression and SERT activity by measuring 5-HT uptake. The results showed that apical TLR2 activation inhibits SERT activity in Caco-2/TC7 cells mainly by reducing SERT protein level either in the plasma membrane, after short-term TLR2 activation or in both the plasma membrane and cell lysate, after long-term activation. cAMP/PKA pathway appears to mediate short-term inhibitory effect of TLR2 on SERT; however, p38 MAPK pathway has been shown to be involved in both short- and long-term TLR2 effect. Reciprocally, 5-HT long-term treatment yielded TLR2 down regulation in Caco-2/TC7 cells. Finally, results from in vivo showed an augmented intestinal SERT expression in mice Tlr2-/-, thus confirming our inhibitory effect of TLR2 on intestinal SERT in vitro. The present work infers that TLR2 may act in intestinal pathophysiology, not only by its inherent innate immune role, but also by regulating the intestinal serotoninergic system.
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Affiliation(s)
- Eva Latorre
- Departamento Farmacología y Fisiología, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza. Spain
- RNA—Mediated Mechanisms of Disease, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School. Exeter. United Kingdom
- * E-mail:
| | - Elena Layunta
- Departamento Farmacología y Fisiología, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza. Spain
- Instituto Agroalimentario de Aragón–IA2- (Universidad de Zaragoza–CITA), Zaragoza, Spain
| | - Laura Grasa
- Departamento Farmacología y Fisiología, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza. Spain
- Instituto Agroalimentario de Aragón–IA2- (Universidad de Zaragoza–CITA), Zaragoza, Spain
| | - Marta Castro
- Departamento Farmacología y Fisiología, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza. Spain
- Instituto Agroalimentario de Aragón–IA2- (Universidad de Zaragoza–CITA), Zaragoza, Spain
| | - Julián Pardo
- Departamento Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza, Spain
| | - Fernando Gomollón
- Servicio de Sistema Digestivo. Hospital Clínico Universitario "Lozano Blesa", Instituto de Investigación Sanitaria de Aragón (IIS); Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Zaragoza, Spain
| | - Ana I. Alcalde
- Departamento Farmacología y Fisiología, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza. Spain
- Instituto Agroalimentario de Aragón–IA2- (Universidad de Zaragoza–CITA), Zaragoza, Spain
| | - José E. Mesonero
- Departamento Farmacología y Fisiología, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza. Spain
- Instituto Agroalimentario de Aragón–IA2- (Universidad de Zaragoza–CITA), Zaragoza, Spain
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Latorre E, Pradilla A, Chueca B, Pagán R, Layunta E, Alcalde AI, Mesonero JE. Listeria monocytogenes Inhibits Serotonin Transporter in Human Intestinal Caco-2 Cells. Microb Ecol 2016; 72:730-739. [PMID: 27488594 PMCID: PMC5023727 DOI: 10.1007/s00248-016-0809-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 06/23/2016] [Indexed: 06/06/2023]
Abstract
Listeria monocytogenes is a Gram-positive bacterium that can cause a serious infection. Intestinal microorganisms have been demonstrated to contribute to intestinal physiology not only through immunological responses but also by modulating the intestinal serotonergic system. Serotonin (5-HT) is a neuromodulator that is synthesized in the intestinal epithelium and regulates the whole intestinal physiology. The serotonin transporter (SERT), located in enterocytes, controls intestinal 5-HT availability and therefore serotonin's effects. Infections caused by L. monocytogenes are well described as being due to the invasion of intestinal epithelial cells; however, the effect of L. monocytogenes on the intestinal epithelium remains unknown. The main aim of this work, therefore, was to study the effect of L. monocytogenes on SERT. Caco2/TC7 cell line was used as an enterocyte-like in vitro model, and SERT functional and molecular expression assays were performed. Our results demonstrate that living L. monocytogenes inhibits serotonin uptake by reducing SERT expression at the brush border membrane. However, neither inactivated L. monocytogenes nor soluble metabolites were able to affect SERT. The results also demonstrate that L. monocytogenes yields TLR2 and TLR10 transcriptional changes in intestinal epithelial cells and suggest that TLR10 is potentially involved in the inhibitory effect observed on SERT. Therefore, L. monocytogenes, through TLR10-mediated SERT inhibition, may induce increased intestinal serotonin availability and potentially contributing to intestinal physiological changes and the initiation of the inflammatory response.
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Affiliation(s)
- E Latorre
- Departamento Farmacología y Fisiología, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza, Spain.
- RNA-Mediated Mechanisms of Disease, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, UK.
| | - A Pradilla
- Departamento Farmacología y Fisiología, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza, Spain
| | - B Chueca
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain
- Instituto Agroalimentario de Aragón - IA2, Universidad de Zaragoza - CITA, Zaragoza, Spain
| | - R Pagán
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain
- Instituto Agroalimentario de Aragón - IA2, Universidad de Zaragoza - CITA, Zaragoza, Spain
| | - E Layunta
- Departamento Farmacología y Fisiología, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza, Spain
- Instituto Agroalimentario de Aragón - IA2, Universidad de Zaragoza - CITA, Zaragoza, Spain
| | - A I Alcalde
- Departamento Farmacología y Fisiología, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza, Spain
- Instituto Agroalimentario de Aragón - IA2, Universidad de Zaragoza - CITA, Zaragoza, Spain
| | - J E Mesonero
- Departamento Farmacología y Fisiología, Facultad de Veterinaria, Instituto de Investigación Sanitaria de Aragón (IIS), Universidad de Zaragoza, Zaragoza, Spain
- Instituto Agroalimentario de Aragón - IA2, Universidad de Zaragoza - CITA, Zaragoza, Spain
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