Natural Killer Cell Immunophenotypic Abnormalities in Secondary Syphilis Patients

Event Abstract Back to Event Natural Killer Cell Immunophenotypic Abnormalities in Secondary Syphilis Patients Lady G. Ramirez Hincapié1*, Adriana R. Cruz1*, Juan P. Garcés1, María A. Castrillón1, Domenico Mavilio2, Kelly Hawley3, Justin D. Radolf3 and Juan C. Salazar4 1 Centro Internacional de Entrenamiento e Investigaciones Medicas CIDEIM, Colombia 2 Istituto Clinico Humanitas, Italy 3 University of Connecticut Health Center, United States 4 University of Connecticut Health Center, Connecticut Children's Medical Center, Department of Pediatrics, United States Secondary syphilis is a chronic sexually transmitted disease caused by Treponema pallidum (Tp) that occurs in stages. It is a serious worldwide public health problem, where more than 10.5 million cases occur each year. Despite the robust innate and adaptive immune responses elicited by Tp during secondary syphilis (SS), it may take several weeks to months for host defenses to gain control of the infection. Natural Killer (NK) cells have the ability to kill infected cells without prior sensitization and modulate innate and adaptive immunity by secreting immunoregulatory chemokines and cytokines, including IFN-g. Signaling through NK cell surface activation and inhibition receptors strictly regulate these activities. We previously showed that NK-cells were a principal source of IFN-g in Tp-stimulated peripheral blood mononuclear cells (PBMCs) ex vivo, and that SS patients experienced significant decreases in total circulating NK-cell numbers with re-distribution of NK cell subsets and evident emergence of a CD56neg subpopulation. The purpose of this study is to further characterize NK cell subpopulations, activation and inhibition receptor expression and functionality in the blood of SS patients and to understand if anomalies in this cell line play a role in the prolonged nature of disease manifestations. A total of 15 SS patients (RPR ≥1:8, treponemic test +, HIV/HBV/HCV -) and 15 healthy controls were recruited in Cali, Colombia. Circulating NK-cells were classified by flow cytometry into three different sub-populations (Regions (R) according to their relative expression of CD16 and CD56 (R1: CD56bright; R2: CD56dim/CD16bright and R3:CD56neg/CD16bright). NK inhibition (CD85j, CD94, CD158a, CD158b, CD158e, LAIR, NKG2A, Siglec7) and activation receptors (DNAM-1, NKG2C, NKp30, NKp44, NKp46, NKp80, NTBA, 2B4) were characterized. Functional profiles were measured upon IFN-g and CD107a expression. Files were analyzed using FlowJo and statistical analysis was conducted using GraphPad prism 4.0 and R software where p-values of < 0.05 were considered significantly different between patients and controls. All study procedures were reviewed and approved by the CIDEIM Institutional Review Board. SS patients exhibited significantly lower number distributions of NK cells when compared with healthy subjects. No significant differences were identified in R1 and R2 among SS and healthy participants; however, consistent with our previous studies, a significant increase in CD56neg cell subpopulations (R3) was observed in our SS cohort compared to healthy controls. Expression of potent inhibitory receptors (CD94/NKG2A, CD85j, CD158b, and LAIR) that recruit tyrosine phosphatase SHP1 and subsequently block NK cell activation at most proximal steps, were clearly enhanced in SS NK cell subsets when compared with healthy controls. Simultaneously, activation receptors from the Natural Cytotoxicity Receptor Family (NCR), NKp30, NKp44, NKp46, and other receptors considered co-stimulatory 2B4, NKp80 were significantly expressed across NK cell subsets in SS patients. Intracellular staining demonstrated IFN-g production in cytokine-producing NK cell subset (R1) upon stimulation, that was significantly greater in SS patients when compared to healthy controls. In contrast, cytotoxic activity was lower across all SS NK cell subsets and differences were significant, particularly in cytotoxic NK cell subpopulation (R2). NK cells can recognize antibody-opsonized or unopsonized cells and lead to target cell lysis as well as to the production of cytokines. They also engage in crosstalk with Dendritic Cells (DC) and are key in macrophage activation through IFNg production. Although NK cells have been traditionally described as pivotal in viral infected or neoplasic cells, we believe that they have an important role in Tp clearance. Although we cannot affirm whether they promote or hamper spirochetal clearance, we can speculate they may delay it, based on the protracted nature of untreated syphilis infection. Marked NK cell subpopulation changes in peripheral blood of a cohort of SS patients could be the result of the systemic effect of chronic Tp infection in the bone marrow or the redistribution and depletion of NK cells into infected tissues including skin. In addition, and strikingly, variation in expression of activation/inhibition receptors could be interpreted as evidence of NK cells role in macrophage regulation and stressed cell recognition. Decreased cytotoxic capacity in SS subjects as demonstrated in CD107a cytolytic assays support our hypothesis that NK cell dysfunction in syphilis may contribute to immune system difficulties in leading to efficient immune response and bacterial clearance. Acknowledgements We gratefully acknowledge the patients who participated in this study. This work received support from Fogarty/NIH R03TW009172, COLCIENCIAS 222956933229 and Connecticut Children’s Medical Center. Keywords: NK cells, Syphilis Patients, Expression, receptors, dysfunction 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: Oral Presentation Topic: Innate Immunity Citation: Ramirez Hincapié LG, Cruz AR, Garcés JP, Castrillón MA, Mavilio D, Hawley K, Radolf JD and Salazar JC (2015). Natural Killer Cell Immunophenotypic Abnormalities in Secondary Syphilis Patients. 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.2015.05.00305 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: 14 May 2015; Published Online: 15 Sep 2015. * Correspondence: Mrs. Lady G Ramirez Hincapié, Centro Internacional de Entrenamiento e Investigaciones Medicas CIDEIM, Cali, Colombia, giovanna1126@gmail.com MD. Adriana R Cruz, Centro Internacional de Entrenamiento e Investigaciones Medicas CIDEIM, Cali, Colombia, acruz@cideim.org.co 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 Lady G Ramirez Hincapié Adriana R Cruz Juan P Garcés María A Castrillón Domenico Mavilio Kelly Hawley Justin D Radolf Juan C Salazar Google Lady G Ramirez Hincapié Adriana R Cruz Juan P Garcés María A Castrillón Domenico Mavilio Kelly Hawley Justin D Radolf Juan C Salazar Google Scholar Lady G Ramirez Hincapié Adriana R Cruz Juan P Garcés María A Castrillón Domenico Mavilio Kelly Hawley Justin D Radolf Juan C Salazar PubMed Lady G Ramirez Hincapié Adriana R Cruz Juan P Garcés María A Castrillón Domenico Mavilio Kelly Hawley Justin D Radolf Juan C Salazar Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. 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