Decidualized human decidual stromal cells inhibit chemotaxis of activated T cells: a potential mechanism of maternal-fetal immune tolerance.

Background: Numerous lines of evidence confirm that decidual stromal cells (DSCs) play a key role in maternal-fetal immune tolerance. Under the influence of progesterone and other hormones, the DSCs go through a process of differentiation (decidualization) during normal pregnancy. In mice, DSCs inhibit the expression of chemokines that attract abortigenic Th1 and Tc cells to the decidua. We have studied this phenomenon in humans. Methods: We established human DSC lines and decidualized these cells in vitro with progesterone and cAMP. We determined the expression of the chemokines CXCL9, CXCL10 and CXCL11, whose receptor CXCR3 is expressed by Th1 and Tc cells, in undifferentiated DSCs and decidualized DSCs by qRT-PCR. Activated CD3+CXCR3+ cells, including CD4+ Th1 cells and CD8+ Tc cells, were induced in vitro. The migration capacity of these activated lymphocytes was investigated in Transwell chambers with conditioned media from undifferentiated and decidualized DSCs. Results: We demonstrated that CXCL9 was not expressed by DSCs, whereas the expression of CXCL10 and CXCL11 was inhibited in decidualized cells. Conditioned media from decidualized cells significantly inhibited the migration of Th1 and Tc cells. We found that decidualized cells secrete factors of MW less than 6000-8000 Da, which actively inhibit the chemotaxis of these lymphocytes. Discussion: These results confirm in humans that decidualization of DSCs inhibits the expression by these cells of chemokines that attract Th1 and Tc cells and induces the secretion by DSCs of factors that inhibit the chemotaxis of these lymphocytes, thus preventing the arrival of abortigenic T cells in the decidua.

Influence of the ectopic location on the antigen expression and functional characteristics of endometrioma stromal cells.

RESEARCH QUESTION: Are the alterations observed in the endometriotic cells, such as progesterone resistance, already present in the eutopic endometrium or acquired in the ectopic location? DESIGN: The response to decidualization with progesterone and cyclic AMP for up to 28 days was compared in different endometrial stromal cell (EnSC) lines established from samples of endometriomas (eEnSC), eutopic endometrium from women with endometriosis (eBEnSC), endometrial tissue from healthy women (BEnSC) and menstrual blood from healthy donors (mEnSC). RESULTS: Usual features of decidualized cells, such as changes in cell morphology and expression of prolactin, were similarly observed in the three types of eutopic EnSC studied, but not in the ectopic cells upon decidualization. Among the phenotypic markers analysed, CD105 was down-regulated under decidualization in all cell types (mEnSC, P = 0.005; BEnSC, P = 0.029; eBEnSC, P = 0.022) except eEnSC. mEnSC and BEnSC underwent apoptosis during decidualization, whereas eBEnSC and eEnSC were resistant to the induction of cell death. Lastly, migration studies revealed that mEnSC secreted undetermined factors during decidualization that inhibited cell motility, whereas eEnSC showed a significantly lower ability to produce those migration-regulating factors (P < 0.0001, P  < 0.001 and P = 0.0013 for the migration of mEnSC at 24, 48 and 72 h, respectively; P  < 0.0001 for the migration of eEnSC at all times studied). CONCLUSIONS: This study provides novel insights into the differences between endometriotic and eutopic endometrial cells and reinforces the idea that the microenvironment in the ectopic location plays additional roles in the acquisition of the alterations that characterize the cells of the endometriotic foci.

Stromal cells of the endometrium and decidua: in search of a name and an identity†.

Human endometrial and decidual stromal cells are the same cells in different environments (nonpregnancy and pregnancy, respectively). Although some authors consider decidual stromal cells to arise solely from the differentiation of endometrial stromal cells, this is a debatable issue given that decidualization processes do not end with the formation of the decidua, as shown by the presence of stromal cells from both the endometrium and decidua in both undifferentiated (nondecidualized) and decidualized states. Furthermore, recent functional and transcriptomic results have shown that there are differences in the decidualization process of endometrial and decidual stromal cells, with the latter having a greater decidualization capacity than the former. These differences suggest that in the terminology and study of their characteristics, endometrial and decidual stromal cells should be clearly distinguished, as should their undifferentiated or decidualized status. There is, however, considerable confusion in the designation and identification of uterine stromal cells. This confusion may impede a judicious understanding of the functional processes in normal and pathological situations. In this article, we analyze the different terms used in the literature for different types of uterine stromal cells, and propose that a combination of differentiation status (undifferentiated, decidualized) and localization (endometrium, decidua) criteria should be used to arrive at a set of accurate, unambiguous terms. The cell identity of uterine stromal cells is also a debatable issue: phenotypic, functional, and transcriptomic studies in recent decades have related these cells to different established cells. We discuss the relevance of these associations in normal and pathological situations.

Decidualization modulates the mesenchymal stromal/stem cell and pericyte characteristics of human decidual stromal cells. Effects on antigen expression, chemotactic activity on monocytes and antitumoral activity.

Decidual stromal cells (DSCs) are the most abundant cellular component of human decidua and play a central role in maternal-fetal immune tolerance. Antigen phenotyping and functional studies recently confirmed the relationship of DSCs with mesenchymal stem/stromal cells (MSCs) and pericytes, the latter two cell types being closely related or identical. The present study investigated the effect of decidualization, a process of cell differentiation driven by progesterone (P4) and other pregnancy hormones, on the MSC/pericyte characteristics of DSCs. To this end we isolated undifferentiated DSC (preDSC) lines that were decidualized in vitro (dDSC) by the effect of P4 and cAMP. Using flow cytometry, we found significant downmodulation of the expression of the MSC/pericyte markers α-smooth muscle actin, nestin, CD140b, CD146 and SUSD2 in dDSCs. The dDSCs did not differ, compared to preDSCs, in the expression of angiogenic factors (characteristic of pericytes) HGF, FGF2, ANGPT1 or VEGF according to RT-PCR results, but had significantly increased PGF expression. In migration assays, preDSC-conditioned media had a chemotactic effect on the THP-1 monocytic line (characteristic of pericytes), and this effect was significantly greater in dDSC-conditioned media. Media conditioned with dDSC, but not with preDSC, induced apoptosis in 4 out of 6 different tumor cell lines (characteristic of MSCs) according to propidium iodide staining and flow cytometry results. Our findings show that decidualization induces phenotypic and functional changes in the MSC/pericyte properties of DSCs that may have a role in the normal development of pregnancy.

Perinatal Derivatives: Where Do We Stand? A Roadmap of the Human Placenta and Consensus for Tissue and Cell Nomenclature.

Progress in the understanding of the biology of perinatal tissues has contributed to the breakthrough revelation of the therapeutic effects of perinatal derivatives (PnD), namely birth-associated tissues, cells, and secreted factors. The significant knowledge acquired in the past two decades, along with the increasing interest in perinatal derivatives, fuels an urgent need for the precise identification of PnD and the establishment of updated consensus criteria policies for their characterization. The aim of this review is not to go into detail on preclinical or clinical trials, but rather we address specific issues that are relevant for the definition/characterization of perinatal cells, starting from an understanding of the development of the human placenta, its structure, and the different cell populations that can be isolated from the different perinatal tissues. We describe where the cells are located within the placenta and their cell morphology and phenotype. We also propose nomenclature for the cell populations and derivatives discussed herein. This review is a joint effort from the COST SPRINT Action (CA17116), which broadly aims at approaching consensus for different aspects of PnD research, such as providing inputs for future standards for the processing and in vitro characterization and clinical application of PnD.

Effect of flavonoids on rat splenocytes, a structure-activity relationship study.

Flavonoids are polyphenols frequently consumed in the diet which have been suggested to exert a number of beneficial actions on human health, including intestinal anti-inflammatory activity. Their properties have been studied in numerous cell types, but little is known about their effect on leukocyte biology. We have selected 9 flavonoids (extended to 14 flavonoids plus the related polyphenol resveratrol in some cases) with different structural features to characterize their effects on leukocyte viability, proliferation, and expression of cyclooxygenase 2 (EC 1.14.99.1), inducible nitric oxide synthase (iNOS, EC 1.14.13.39) and proinflammatory cytokines (TNF-alpha, IFN-gamma, IL-2), as well as to elucidate the structural requirements in each case. Quiescent and concanavalin A-stimulated rat splenocytes were used as a model. Flavonoids (50 microM) had a dramatic inhibitory effect on cytokine secretion. Inducible nitric oxide synthase expression was also blocked largely by some flavonoids, especially quercetin, luteolin and apigenin, while cyclooxygenase 2 was downregulated only by apigenin, diosmetin and quercetin. Apigenin, luteolin, genistein and quercetin had substantial cytotoxic/proapoptotic effects, while chrysin, daidzein, hesperetin and kaempferol did not reduce cell viability. In contrast, all flavonoids had powerful antiproliferative effects. However, none of the compounds activated caspase 3 (EC 3.4.22.56), but actually lowered caspase 3 activation and expression in concanavalin A-stimulated cells. The activity of the quercetin metabolite isorhamnetin was generally lower than that of the parent compound. We conclude that flavonoids have powerful effects on lymphocytes with distinct structural requirements that may contribute to their intestinal anti-inflammatory activity. The bioactivity of orally administered flavonoids may be dampened by biotransformation in vivo, particularly in extraintestinal sites.

Human decidual stromal cells express HLA-G: Effects of cytokines and decidualization.

BACKGROUND: Decidual stromal cells (DSC) are the main cellular component of the decidua, the maternal tissue in close contact with fetal trophoblast. Although of mesenchymal origin, DSC exert numerous immune functions that seem to be relevant for the immunological relationship between the mother and fetus. HLA-G, an antigen preferentially expressed by trophoblast, appears to participate in the immune tolerance by the mother of the semiallogeneic fetus. METHODS AND RESULTS: We show by flow cytometry, fluorescence microscopy, western blotting and RT-PCR that DSC isolated and maintained in culture express HLA-G weakly but consistently. We also detected this antigen by flow cytometry in fresh DSC. Interleukin (IL)-10, a cytokine associated with normal pregnancy, increased the expression of HLA-G by DSC (P < 0.00001), whereas IL-2, a cytokine involved in spontaneous abortion, showed no effect. Decidualization by progesterone and cAMP also up-regulated the expression of HLA-G by DSC (P < 0.001). Interferon gamma, a cytokine implicated in the vascular remodelling of the decidua necessary for embryo implantation, also increased the expression of HLA-G by DSC (P < 0.05). CONCLUSIONS: Our results suggest the existence of a network in which hormones together with cytokines regulate the expression of HLA-G by DSC, and that may be of relevance in the maintenance of maternal-fetal tolerance.

Follicular dendritic cells are related to bone marrow stromal cell progenitors and to myofibroblasts.

Follicular dendritic cells (FDC) are involved in the presentation of native Ags to B cells during the secondary immune response. Some authors consider FDC to be hemopoietic cells, whereas others believe them to be mesenchymal cells. The low proportion of FDC in the lymphoid follicle, together with technical difficulties in their isolation, make these cells difficult to study. We show that Fibroblast Medium can be used successfully to isolate and maintain FDC lines. In this culture medium, we obtained 18 FDC lines from human tonsils, which proliferated for as long as 18 wk and showed a stable Ag phenotype as detected by flow cytometry and RT-PCR. FDC lines were CD45-negative and expressed Ags associated to FDC (CD21, CD23, CD35, CD40, CD73, BAFF, ICAM-1, and VCAM-1) and Ags specific for FDC (DRC-1, CNA.42, and HJ2). These cell lines were also able to bind B cells and secrete CXCL13, functional activities characteristic of FDC. Nevertheless, the additional expression of STRO-1, together with CD10, CD13, CD29, CD34, CD63, CD73, CD90, ICAM-1, VCAM-1, HLA-DR, alkaline phosphatase, and alpha-smooth muscle actin (alpha-SM actin) indicated that FDC are closely related to bone marrow stromal cell progenitors. The expression of alpha-SM actin also relates FDC with myofibroblasts. Like myofibroblasts, FDC lines expressed stress fibers containing alpha-SM actin and were able to contract collagen gels under the effect of TGFbeta1 and platelet-derived growth factor. These findings suggest that FDC are a specialized form of myofibroblast and derive from bone marrow stromal cell progenitors.

Contractile activity of human decidual stromal cells. II. Effect of interleukin-10.

CONTEXT: Human decidual stromal cells (DSC) are myofibroblast-like cells that express alpha-smooth muscle (alpha-SM) actin, a protein associated with cell contractility. Several lines of experimental evidence in humans and mice show that antiinflammatory cytokines favor normal pregnancy, whereas Th1 and inflammatory cytokines play a role in abortion. We previously demonstrated that IL-2, a Th1 cytokine, increased the contractility of human DSC. OBJECTIVE: We studied the effect of the antiinflammatory cytokines IL-10 and IL-4 on the contractility of DSC from first-trimester pregnancy. SETTING AND PATIENTS: We studied 10 healthy women who underwent elective vaginal termination of first-trimester pregnancy at Clínica El Sur, Málaga, and Clínica Ginegranada, Granada. MAIN OUTCOME MEASURE(S): After isolation of DSC, cell contractility was measured with the collagen gel contraction assay. alpha-SM actin was detected with Western blotting and immunofluorescence. RESULTS: We found that IL-10, but not IL-4, increased the volume of the collagen gel matrixes in which the cytokine-treated DSC were cultured, showing that IL-10 decreased DSC contractility. By Western blotting we demonstrated that this effect was not related to an alteration in the synthesis of alpha-SM actin. Nevertheless, we observed by immunofluorescence microscopy that DSC treated with IL-10 exhibited stress fibers with a lower content of alpha-SM actin than untreated control DSC. CONCLUSIONS: IL-10 relaxes DSC by reducing the incorporation of alpha-SM actin into their stress fibers. This relaxing activity may be of relevance for the maintenance of pregnancy.

Dietary nucleotides accelerate changes in intestinal lymphocyte maturation in weanling mice.

OBJECTIVE: Nucleotides, the building blocks of nucleic acids, are normal components of the mammalian diet. These molecules have been implicated in biologic processes, such as the stimulation of the immunologic response. Nucleotides have also been considered as conditionally essential nutrients for infant formulas. The authors evaluated the influence of dietary nucleotides on the expression of several surface antigens by different intestinal lymphocyte populations in weanling mice. METHODS: Mice at weaning were fed a semipurified diet with or without 3 g/kg of each of the following nucleotides: adenosine monophosphate, cytosine monophosphate, guanosine monophosphate, and uridine monophosphate. Animals were killed at different times (0, 4, 7, 12, and 18 days) after weaning, and lymphocytes from intestinal Peyer's patches, epithelium, and lamina propria were isolated. The expression of different antigens (CD3, CD4, CD8alpha, CD8beta, TCRalphabeta, TCRgammadelta, CD5, CD22 and CD45R) was analyzed by flow cytometry. RESULTS: The expression of these antigens changed parallel to the maturation of the lymphocytes from Peyer's patches, epithelium, and lamina propria. However, developmental changes of expression for most of the antigens occurred sooner in the animals fed the diet supplemented with nucleotides. The expression of T and B antigens was different in the lymphocyte populations analyzed and also changed according to the diet within each population. In general, nucleotides promoted the expression of B- and T-helper cell antigens. CONCLUSIONS: The authors conclude that dietary nucleotides may affect the process of maturation and differentiation of intestinal lymphocytes, which usually takes place at weaning.

Contractile activity of human decidual stromal cells.

We previously demonstrated that human decidual stromal cells (DSC), the main cellular component of the decidua, are similar in antigen phenotype and structure to myofibroblasts, cells with contractile activity. In this work we isolated and maintained DSC in fibroblast medium, in which these cells show a stable phenotype similar to that of DSC in vivo. Flow cytometric observations showed that most DSC expressed alpha-smooth muscle (alpha-SM) actin, an intermediate filament that is considered a marker of myofibroblasts and is responsible for the contractile activity of these cells. alpha-SM actin mRNA was detected by RT-PCR in these cells. The contractile activity of DSC was determined by the gel contraction assay; we found that TGF beta 1 and platelet-derived-growth factor, cytokines that are known to be inducers of myofibroblast contractility, also induced contractility of DSC. IL-2, a Th1 cytokine-related with spontaneous abortion, also activated DSC contractility. Our results confirmed that DSC are phenotypically and functionally related with myofibroblast.

Absolute counts and distribution of lymphocyte subsets in small intestine of BALB/c mice change during weaning.

The gut immune system is an essential part of the barrier function of the gut. At weaning, major changes can be expected in the number and subset composition of lymphocytes in the small intestine since the gut is exposed to a wide variety of food and microbial antigens, especially when human milk is gradually replaced by weaning foods. The purpose of this study was to evaluate the changes in small intestine lymphocyte subsets in mice during weaning. BALB/c male mice at weaning (3 wk old) were fed a nonpurified diet for 18 d and were killed at different times (0, 4, 7, 12 and 18 d). Lymphocyte populations from lamina propria (LPL), Peyer's patches (PPL) and intestinal epithelium (IEL) were isolated. The expression of different antigens (CD3, CD4, CD8alpha, CD8beta, CD22 and CD45R) in those lymphocyte populations was analyzed by flow cytometry. The percentages of cells expressing T-cell antigens, such as CD3, were significantly higher in LPL during weaning compared to d 0. The percentages of cells expressing CD8alpha and CD8beta increased in both IEL and LPL. However, the percentage of CD4+ cells tended (P = 0.07) to decrease in IEL and to increase in LPL. The percentages of cells expressing B-cell antigens, such as CD22 or CD45R in PPL increased. Changes in the specific phenotypes of intestinal lymphocyte populations at weaning are apparently related to the maturation of the intestinal immune system during early life. Thus, B cells increase in PPL and T cell increase in IEL and LPL.

Decidual lymphocytes of human spontaneous abortions induce apoptosis but not necrosis in JEG-3 extravillous trophoblast cells.

The human decidua contains an unusually high proportion of lymphocytes, mainly NK and T cells, which are potentially cytotoxic to the trophoblast when they are stimulated with certain cytokines. Given the high incidence of spontaneous abortion in humans and other species, our working hypothesis is that decidual lymphocytes are involved in immunological mechanisms that attack the trophoblast and induce abortion when any gestational problem arises. To test this hypothesis, flow cytometry was used to compare decidual lymphocyte populations in first-trimester spontaneous abortions and elective terminations of first-trimester pregnancy. We found significantly higher proportions of decidual lymphocytes that expressed activation markers, and of T cells (mainly T helper cells) in spontaneous abortions than in elective terminations of pregnancy. Decidual lymphocytes from spontaneous abortion, like decidual lymphocytes from elective termination of pregnancy and peripheral blood lymphocytes, were however, unable to lyse the JEG-3 extravillous cytotrophoblast cell line in a (51)Cr-release assay. Nevertheless, decidual lymphocytes from spontaneous abortion, unlike decidual lymphocytes from elective termination of pregnancy and peripheral blood lymphocytes, induced apoptosis in JEG-3 cells as determined by DNA fragment-release assay. Hematoxylin and eosin staining showed a significantly higher proportion of apoptotic JEG-3 cells when these cells were treated with decidual lymphocytes from spontaneous abortion than when JEG-3 cells were cultured with decidual lymphocytes from elective termination of pregnancy. The ultrastructural signs of apoptosis were confirmed by electron microscopy. These data support the hypothesis that activated decidual lymphocytes participate in human spontaneous abortion by inducing apoptosis but not necrosis of the trophoblast.