The IgG Fc receptor, CD16, interacts with LPS and is internalized during the in vitro stimulation of human monocytes.

Event Abstract Back to Event The IgG Fc receptor, CD16, interacts with LPS and is internalized during the in vitro stimulation of human monocytes. Natsuko Paniagua1, Cesar García1, Alfonso Salgado2, Laura Ventura-Ayala3, María Del Carmen Navarro2, Martha Torres4, Esmeralda Juárez4 and Sigifredo Pedraza-Sanchez3* 1 Instituto Tecnológico y de Estudios Superiores de Monterrey, Campus Ciudad de México, Mexico 2 Instituto Nacional de Enfermedades Respiratorias, Laboratorio de Investigación en Enfermedades Reumáticas, Mexico 3 Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Biochemestry, Mexico 4 Instituto Nacional de Enfermedades Respiratorias, Departamento de Investigación en Microbiología, Mexico Background. The lipopolysaccharide (LPS) is an essential cell wall componenet of Gram Negative bacteria, it is the most studied PAMP and its receptor on CD14 + monocytes is formed at least by TLR4 and MD2. During a bacterial infection, stimulation of monocytes with LPS induces the production of pro-inflammatory cytokines which are secreted and they are involved in innate immunity aimed to stop infections, but overproduction of those cytokines can be harmful, causing tissue damage or even the death of individual. During the recognition of LPS by TLR4 there are other molecules that associate to LPS receptor and form a multimolecular complex which is not known in detail whether they participate in the recognition of LPS or in intracellular signaling induced during activation. Among such molecules recruited to CD14 and TLR4 in response to LPS, there are Fc receptors for IgG (FcyR), CD64, CD32 and CD16. Considering that there are at least two phenotype and functional monocyte subsets on basis to CD16 expression, (CD14 +, CD16-, classical monocytes and CD14 +, CD16 +, inflammatory monocytes) and that inflammatory monocytes produce more proinflammatory cytokines in response to LPS, we hypotesized that this or other FcyR may be involved in LPS recognition or signaling during the LPS-induced activation in human monocytes. Methods: Mononuclear cells (MNC) from human blood or CD14 + monocytes purified by positive immunomagnetic selection were labeled on membrane with CD16, CD14 and TLR4 with fluorochrome labeled monoclonal antibodies and in some experiments cells were also simultaneously labeled with LPS-Alexa Fluor 488. The cells were fixed immediately with paraformaldehyde or in other experiments, after membrane labeling cells were incubated for 1h at 37 ° C and 5% CO2 in the presence or absence of LPS or LTA, a TLR2 agonist; aliquots of cells were fixed and harvested at several time points and fluorescent markers were analyzed by flow cytometry or fluorescence or confocal microscopy. Results: It was found by flow cytometry that the subpopulation of CD14 + CD16 + binds more LPS-AF488 than any other cell population in MNC. Then, we observed in purified CD14+ monocytes, that CD16 and TLR4 moved from cell membrane to intracellular localization upon activation with LPS and that these molecules are co-located. In contrast, LTA a TLR2 agonist, does not induce the same phenomenon. Stimulation of monocytes with fluorescent LPS (LPS-AF488) shows internalization similar to CD16 and TLR4, but trimolecular colocalization needs to be determined. Conclusion: Our results suggest the possible direct interaction between CD16 and TLR4 duringLPS activation of human monocytes. More studies are required to determine if other FcyR directly participate in LPS binding and internalization and if such process take part in cytokine production. Keywords: TLR4, Fc gamma receptors, Human monocyte, LPS receptor, Monocyte activation Conference: IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología, Medellin, Colombia, 13 Oct - 16 Oct, 2015. Presentation Type: Poster Presentation Topic: Innate Immunity Citation: Paniagua N, García C, Salgado A, Ventura-Ayala L, Navarro M, Torres M, Juárez E and Pedraza-Sanchez S (2015). The IgG Fc receptor, CD16, interacts with LPS and is internalized during the in vitro stimulation of human monocytes.. Front. Immunol. Conference Abstract: IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología. doi: 10.3389/conf.fimmu.2015.05.00372 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 01 Jun 2015; Published Online: 16 Sep 2015. * Correspondence: PhD. Sigifredo Pedraza-Sanchez, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Biochemestry, Mexico, Distrito Federal, 14080, Mexico, sigifredo.pedraza9@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Natsuko Paniagua Cesar García Alfonso Salgado Laura Ventura-Ayala María Del Carmen Navarro Martha Torres Esmeralda Juárez Sigifredo Pedraza-Sanchez Google Natsuko Paniagua Cesar García Alfonso Salgado Laura Ventura-Ayala María Del Carmen Navarro Martha Torres Esmeralda Juárez Sigifredo Pedraza-Sanchez Google Scholar Natsuko Paniagua Cesar García Alfonso Salgado Laura Ventura-Ayala María Del Carmen Navarro Martha Torres Esmeralda Juárez Sigifredo Pedraza-Sanchez PubMed Natsuko Paniagua Cesar García Alfonso Salgado Laura Ventura-Ayala María Del Carmen Navarro Martha Torres Esmeralda Juárez Sigifredo Pedraza-Sanchez Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.