A potential tolerogenic immune mechanism in a trophoblast cell line through the activation of chemokine-induced T cell death and regulatory T cell modulation.
BACKGROUND
Successful implantation is followed by a local pro-inflammatory and Th1 response, subsequently controlled by Th2. Regulated upon activation, normal T cell expressed and secreted (RANTES) promotes a Th1 response and is implicated as a physiologic tolerogenic factor; therefore, we studied its potential role in the trophoblast-maternal leukocyte dialog.


METHODS
We performed co-cultures of immortalized trophoblast cell line (Swan 71) and peripheral blood mononuclear cells (PBMCs) from fertile women (n = 23) or with recurrent spontaneous abortions (n = 18, RSA). After 24 and 48 h, supernatant and cells were analyzed by enzyme-linked immunosorbent assay, fluorescence-activated cell sorting, Western blot and apoptosis assay. To investigate the physiological effects at peripheral level, we co-cultured maternal and paternal PBMCs with conditioned media from Swan cells and progesterone.


RESULTS
Following interaction of maternal PBMCs and trophoblast cells, RANTES production increased (P < 0.05) and was accompanied by low levels of interferon gamma, interleukin-12 p70 and high levels of tumor necrosis factor-alpha, nitrites and leukemia-inhibitory factor. RANTES production resulted in elevated apoptosis of potentially deleterious maternal CD3+ lymphocytes, accompanied by a decrease in the proliferative maternal response. During fetal-maternal dialog, the anti-RANTES antibody significantly reduced the frequency of CD4+CD25+Foxp3+ cells (P < 0.05) and was associated with trophoblast cell survival. However, co-cultures of Swan cells and RSA-PBMCs displayed a differential RANTES kinetics, lower levels of regulatory T cells (Tregs) and CD3+annexin-V+cells, accompanied by higher levels of apoptotic trophoblast cells.


CONCLUSIONS
RANTES promotes an adequate pro-implantatory microenvironment that influences trophoblast cell survival and modulates the balance of maternal Treg/T effector lymphocytes in favor of maternal tolerance.
Fraccaroli
Laura
L
Laboratory of Immunopharmacology, School of Sciences, University of Buenos Aires, Int. Guiraldes 2160, Ciudad Universitaria, Pabellón 2 Piso 4, C1428EHA Buenos Aires, Argentina.
Alfieri
Julio
J
Larocca
Luciana
L
Calafat
Mario
M
Mor
Gil
G
Leirós
Claudia Pérez
CP
Ramhorst
Rosanna
R
D000026:Abortion, Habitual / Q000276:immunology; D017209:Apoptosis / Q000276:immunology*; D015153:Blotting, Western; D002460:Cell Line; D049109:Cell Proliferation; D018946:Chemokine CCL5 / Q000378:metabolism / Q000502:physiology*; D017077:Culture Media, Conditioned; D010064:Embryo Implantation / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000378:metabolism; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology* / Q000502:physiology; D008431:Maternal-Fetal Exchange / Q000276:immunology; D011247:Pregnancy; D054389:Receptors, CCR1 / Q000378:metabolism; D019713:Receptors, CCR5 / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000502:physiology; D014327:Trophoblasts / Q000276:immunology* / Q000378:metabolism / Q000502:physiology
C515300:CCR1 protein, human; D018946:Chemokine CCL5; D017077:Culture Media, Conditioned; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D054389:Receptors, CCR1; D019713:Receptors, CCR5