Periodic Accumulation of Regulatory T Cells in the Uterus: Preparation for the Implantation of a Semi-Allogeneic Fetus?

BACKGROUND: Naturally occurring Foxp3(+)regulatory T cells play an important role in the inhibition of an immunological attack of the fetus. As implantation of the fetus poses an immediate antigenic challenge, the immune system has to prepare itself for this event prior to implantation. METHODOLOGY AND PRINCIPAL FINDINGS: Here, we show using quantitative RT-PCR and flow cytometry that regulatory T cells accumulate in the uterus not only during pregnancy, but also every time the female becomes fertile. Their periodic accumulation is accompanied by matching fluctuations in uterine expression of several chemokines, which have been shown to play a role in the recruitment and retention of regulatory T cells. CONCLUSIONS/SIGNIFICANCE: The data lead us to propose that every time a female approaches estrus, regulatory T cells start to accumulate in the uterus in preparation for a possible implantation event. Once pregnancy is established, those regulatory T cells that have seen alloantigen need to be retained at their site of action. Whilst several chemokines appear to be involved in the recruitment and/or retention of regulatory T cells during estrus, in pregnancy this role appears to be taken over by CCL4

Mifepristone Increases the Cytotoxicity of Uterine Natural Killer Cells by Acting as a Glucocorticoid Antagonist via ERK Activation

Background: Mifepristone (RU486), a potent antagonist of progesterone and glucocorticoids, is involved in immune regulation. Our previous studies demonstrated that mifepristone directly augments the cytotoxicity of human uterine natural killer (uNK) cells. However, the mechanism responsible for this increase in cytotoxicity is not known. Here, we explored whether the increased cytotoxicity in uNK cells produced by mifepristone is due to either anti-progesterone or anti-glucocorticoid activity, and also investigated relevant changes in the mitogen-activated protein kinase (MAPK) pathway. Methodology/Principal Findings: Uterine NK cells were isolated from decidual samples and incubated with different concentrations of progesterone, cortisol, or mifepristone. The cytotoxicity and perforin expression of uNK cells were detected by mitochondrial lactate dehydrogenase-based MTS staining and flow cytometry assays, respectively. Phosphorylation of components of the MAPK signaling pathway was detected by Western blot. Cortisol attenuated uNK cell-mediated cytotoxicity in a concentration-dependent manner whereas progesterone had no effect. Mifepristone alone increased the cytotoxicity and perforin expression of uNK cells; these effects were blocked by cortisol. Furthermore, mifepristone increased the phosphorylation of ERK1/2 in a cortisol-reversible manner. Specific ERK1/2 inhibitor PD98059 or U0126 blocked cortisol- and mifepristone-induced responses in uNK cells

Blood neutrophils from children with COVID-19 exhibit both inflammatory and anti-inflammatory markers

Background: Perhaps reflecting that children with COVID-19 rarely exhibit severe respiratory symptoms and often remain asymptomatic, little attention has been paid to explore the immune response in pediatric COVID-19. Here, we analyzed the phenotype and function of circulating neutrophils from children with COVID-19. Methods: An observational study including 182 children with COVID-19, 21 children with multisystem inflammatory syndrome (MIS-C), and 40 healthy children was performed in Buenos Aires, Argentina. Neutrophil phenotype was analyzed by flow cytometry in blood samples. Cytokine production, plasma levels of IgG antibodies directed to the spike protein of SARS-CoV-2 and citrullinated histone H3 were measured by ELISA. Cell-free DNA was quantified by fluorometry. Findings: Compared with healthy controls, neutrophils from children with COVID-19 showed a lower expression of CD11b, CD66b, and L-selectin but a higher expression of the activation markers HLA-DR, CD64 and PECAM-1 and the inhibitory receptors LAIR-1 and PD-L1. No differences in the production of cytokines and NETs were observed. Interestingly, the expression of CD64 in neutrophils and the serum concentration of IgG antibodies directed to the spike protein of SARS-CoV-2 distinguished asymptomatic from mild and moderate COVID-19. Interpretation: Acute lung injury is a prominent feature of severe COVID-19 in adults. A low expression of adhesion molecules together with a high expression of inhibitory receptors in neutrophils from children with COVID-19 might prevent tissue infiltration by neutrophils preserving lung function.Fil: Seery, Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Raiden, Silvina Claudia. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños Pedro Elizalde (ex Casa Cuna); ArgentinaFil: Algieri, Silvia C.. Hospital Nacional Profesor Alejandro Posadas.; ArgentinaFil: Grisolía, Nicolás A.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños Pedro Elizalde (ex Casa Cuna); ArgentinaFil: Filippo, Daniela. Hospital Municipal Diego Thompson; ArgentinaFil: De Carli, Norberto. Clinica del Niño de Quilmes; ArgentinaFil: Di Lalla, Sandra. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños Pedro Elizalde (ex Casa Cuna); ArgentinaFil: Cairoli, Héctor. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños Pedro Elizalde (ex Casa Cuna); ArgentinaFil: Chiolo, María J.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños Pedro Elizalde (ex Casa Cuna); ArgentinaFil: Meregalli, Claudia N.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños Pedro Elizalde (ex Casa Cuna); ArgentinaFil: Gimenez, Lorena I.. Hospital Municipal Diego Thompson; ArgentinaFil: Gregorio, Gabriela. Hospital Nacional Profesor Alejandro Posadas.; ArgentinaFil: Sarli, Mariam. Hospital Nacional Profesor Alejandro Posadas.; ArgentinaFil: Alcalde, Ana L.. Hospital Nacional Profesor Alejandro Posadas.; ArgentinaFil: Davenport, Carolina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños Pedro Elizalde (ex Casa Cuna); ArgentinaFil: Bruera, María J.. Hospital Nacional Profesor Alejandro Posadas.; ArgentinaFil: Simaz, Nancy. Hospital Nacional Profesor Alejandro Posadas.; ArgentinaFil: Pérez, Mariela F.. Hospital Nacional Profesor Alejandro Posadas.; ArgentinaFil: Nivela, Valeria. Hospital Nacional Profesor Alejandro Posadas.; ArgentinaFil: Bayle, Carola. Hospital Nacional Profesor Alejandro Posadas.; ArgentinaFil: Tuccillo, Patricia. Ministerio de Defensa. Armada Argentina. Hospital Naval Buenos Aires Cirujano Mayor Dr. Pedro Mallo; ArgentinaFil: Agosta, María T.. Ministerio de Defensa. Armada Argentina. Hospital Naval Buenos Aires Cirujano Mayor Dr. Pedro Mallo; ArgentinaFil: Pérez, Hernán. Ministerio de Defensa. Armada Argentina. Hospital Naval Buenos Aires Cirujano Mayor Dr. Pedro Mallo; ArgentinaFil: Villa Nova, Susana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; ArgentinaFil: Suárez, Patricia. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; ArgentinaFil: Takata, Eugenia M.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; ArgentinaFil: García, Mariela. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; ArgentinaFil: Lattner, Jorge. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; ArgentinaFil: Rolón, María J.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; ArgentinaFil: Coll, Patricia. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; ArgentinaFil: Sananez, Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Holgado, María Pía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Ferrero, Fernando. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños Pedro Elizalde (ex Casa Cuna); ArgentinaFil: Geffner, Jorge Raúl. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Arruvito, Maria Lourdes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentin

Regulatory T-cells and immune tolerance in pregnancy: a new target for infertility treatment?

BACKGROUND: Adaptation of the maternal immune response to accommodate the semi-allogeneic fetus is necessary for pregnancy success, and disturbances in maternal tolerance are implicated in infertility and reproductive pathologies. T regulatory (Treg) cells are a recently discovered subset of T-lymphocytes with potent suppressive activity and pivotal roles in curtailing destructive immune responses and preventing autoimmune disease. METHODS: A systematic review was undertaken of the published literature on Treg cells in the ovary, testes, uterus and gestational tissues in pregnancy, and their link with infertility, miscarriage and pathologies of pregnancy. An overview of current knowledge on the generation, activation and modes of action of Treg cells in controlling immune responses is provided, and strategies for manipulating regulatory T-cells for potential applications in reproductive medicine are discussed. RESULTS: Studies in mouse models show that Treg cells are essential for maternal tolerance of the conceptus, and that expansion of the Treg cell pool through antigen-specific and antigen non-specific pathways allows their suppressive actions to be exerted in the critical peri-implantation phase of pregnancy. In women, Treg cells accumulate in the decidua and are elevated in maternal blood from early in the first trimester. Inadequate numbers of Treg cells or their functional deficiency are linked with infertility, miscarriage and pre-eclampsia. CONCLUSIONS: The potency and wide-ranging involvement of Treg cells in immune homeostasis and disease pathology indicates the considerable potential of these cells as therapeutic agents, raising the prospect of their utility in novel treatments for reproductive pathologies.Leigh R. Guerin, Jelmer R. Prins and Sarah A. Robertso

Expansion of CD4+CD25+and FOXP3+ regulatory T cells during the follicular phase of the menstrual cycle: implications for human reproduction.

Regulatory T cells (Tregs) are thought to affect the severity of various infectious and autoimmune diseases. The incidence of autoimmune disease is higher in fertile women than in men. Thus, we investigated whether Treg numbers were modulated during the menstrual cycle by sex hormones. In fertile nonpregnant women, we detected an expansion of CD4(+)CD25(+)FOXP3(+) Tregs in the late follicular phase of the menstrual cycle. This increase was tightly correlated with serum levels of estradiol and was followed by a dramatic decrease in Treg numbers at the luteal phase. Women who have had recurrent spontaneous abortions (RSA) showed similarly low numbers of Tregs at both the follicular and luteal phases, comparable to numbers we observed in postmenopausal women. In addition to decreased numbers, Tregs from women with RSA were also functionally deficient, as higher numbers were required to exert a similar magnitude of suppression to CD4(+)CD25(+)FOXP3(+) cells from fertile women. Consequently, reproductive failure might result from the inability of Tregs in women with RSA to expand during the preimplantatory phase combined with their lower functional capacity. Additionally, the modulation of Treg numbers we observed in fertile women suggests that the stage of the menstrual cycle should be taken into account when Treg numbers are investigated clinically

Galectin-1 confers immune privilege to human trophoblast: Implications in recurrent fetal loss

Mechanisms accounting for protection of the fetal semiallograft from maternal immune cells remain incompletely understood. In previous studies we showed that galectin-1 (Gal1), an immunoregulatory glycan-binding protein, plays key roles in modulating immune responses during murine pregnancies. Here we show that Gal1 fosters immune privilege at the human fetomaternal interface through modulation of multiple tolerance mechanisms. Gal1 was mainly expressed in invasive extravillous trophoblast cells of human first trimester and term placenta in direct contact with maternal tissue. Trophoblast-derived Gal1 was primarily controlled by progesterone and pro-inflammatory cytokines and fostered T cell tolerance by favoring the expansion of CD4+CD25+FoxP3+ regulatory T (Treg) cells, suppressing the secretion of Th1-type cytokines and limiting T cell viability. Targeted inhibition of Gal1 expression through different strategies including Ab-mediated blockade, addition of the specific disaccharide lactose and silencing through retroviral-mediated siRNA strategies prevented these immunoregulatory effects. Consistent with a tolerogenic function for endogenous Gal1, patients with recurrent pregnancy loss showed considerably lower levels of circulating Gal1 and had greatly enhanced frequency of anti-Gal1 autoantibodies in their sera compared with fertile women. Thus, endogenous Gal1 confers immune privilege to human trophoblasts by triggering a broad tolerogenic program, with potential implications in threatened pregnancies.Fil: Ramhorst, Rosanna Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Inmunofarmacología; ArgentinaFil: Giribaldi, María Laura. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Fraccaroli, Laura Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica. Laboratorio de Inmunofarmacología; ArgentinaFil: Toscano, Marta Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Stupirski, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Romero, Marta D.. Laboratorio Inmunopatologia Investigación y Docencia; ArgentinaFil: Durand, Edith Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Química Biológica de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Centro de Investigaciones en Química Biológica de Córdoba; ArgentinaFil: Rubinstein, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Blaschitz, Astrid. Medizinische Universität Graz; AustriaFil: Sedlmayr, Peter. Medizinische Universität Graz; AustriaFil: Genti de Raimondi, Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; ArgentinaFil: Fainboim, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Rabinovich, Gabriel Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina. Universidad de Buenos Aires; Argentin