Macrophage functions are regulated by murine decidual and tumor extracellular matrices

Decidual stromal cell-derived PGE2 regulates macrophage responses to microbial threat

PROBLEM

Bacterial chorioamnionitis causes adverse pregnancy outcomes, yet host-microbial interactions are not well characterized within gestational membranes. The decidua, the outermost region of the membranes, is a potential point of entry for bacteria ascending from the vagina to cause chorioamnionitis. We sought to determine whether paracrine communication between decidual stromal cells and macrophages shaped immune responses to microbial sensing.

METHOD OF STUDY

Decidual cell-macrophage interactions were modeled in vitro utilizing decidualized, telomerase-immortalized human endometrial stromal cells (dTHESCs) and phorbol ester-differentiated THP-1 macrophage-like cells. The production of inflammatory mediators in response to LPS was monitored by ELISA for both cell types, while phagocytosis of bacterial pathogens (Escherichia coli and Group B Streptococcus (GBS)) was measured in THP-1 cells or primary human placental macrophages. Diclofenac, a non-selective cyclooxygenase inhibitor, and prostaglandin E₂ (PGE₂ ) were utilized to interrogate prostaglandins as decidual cell-derived paracrine immunomodulators. A mouse model of ascending chorioamnionitis caused by GBS was utilized to assess the colocalization of bacteria and macrophages in vivo and assess PGE₂ production.

RESULTS

In response to LPS, dTHESC and THP-1 coculture demonstrated enhancement of most inflammatory mediators, but a potent suppression of macrophage TNF-α generation was observed. This appeared to reflect a paracrine-mediated effect of decidual cell-derived PGE₂ . In mice with GBS chorioamnionitis, macrophages accumulated at sites of bacterial invasion with increased PGE₂ in amniotic fluid, suggesting such paracrine effects might hold relevance in vivo.

CONCLUSION

These data suggest key roles for decidual stromal cells in modulating tissue responses to microbial threat through release of PGE₂ .

Limited Colonization Undermined by Inadequate Early Immune Responses Defines the Dynamics of Decidual Listeriosis

The bacterial pathogen Listeria monocytogenes causes foodborne systemic disease in pregnant women, which can lead to preterm labor, stillbirth, or severe neonatal disease. Colonization of the maternal decidua appears to be an initial step in the maternal component of the disease as well as bacterial transmission to the placenta and fetus. Host-pathogen interactions in the decidua during this early stage of infection remain poorly understood. Here, we assessed the dynamics of L. monocytogenes infection in primary human decidual organ cultures and in the murine decidua in vivo A high inoculum was necessary to infect both human and mouse deciduas, and the data support the existence of a barrier to initial colonization of the murine decidua. If successful, however, colonization in both species was followed by significant bacterial expansion associated with an inability of the decidua to mount appropriate innate cellular immune responses. The innate immune deficits included the failure of bacterial foci to attract macrophages and NK cells, cell types known to be important for early defenses against L. monocytogenes in the spleen, as well as a decrease in the tissue density of inflammatory Ly6C^hi monocytes in vivo These results suggest that the infectivity of the decidua is not the result of an enhanced recruitment of L. monocytogenes to the gestational uterus but rather is due to compromised local innate cellular immune responses.

Distribution of CD14+ and CD68+ Macrophages in the Placental Bed and Basal Plate of Women With Preeclampsia and Preterm Labor

OBJECTIVE

Macrophages play a key role in implantation, placentation and parturition. Yet, whether or not the number of macrophages at the fetomaternal interface (basal plate of the placenta and placental bed) is altered in women with preeclampsia is the subject of controversy. The purpose of this study was to compare the immunoreactivity and distribution patterns of CD14 and CD68 positive macrophages in both the basal plate and placental bed from preeclamptic and non-preeclamptic pregnancies.

METHODS

A cross-sectional study was conducted. Paraffin embedded sections of placental tissues and placental bed biopsies were obtained from patients with early onset preeclampsia (n=10) and from those with preterm labor/delivery (n=10) without preeclampsia matched for gestational age. Double immunohistochemistry using antibodies to CD14 and CD68 was performed, and the density of double or single positive cells in the basal plate and placental bed was evaluated. Non-parametric statistics were used for analysis.

RESULTS

1) A unique subset of CD14-/CD68+ cells was identified. The cells in question were present at a higher level in the decidua than in the myometrial segment of the placental bed (p<0.01); 2) The density and proportion of CD14+/CD68+ cells (double positive cells) were significantly higher in the myometrial segment than in the basal plate (p=0.0003); and 3) There were no significant differences in the density and patterns of immunopositive macrophages in the basal plate, the decidua, and the myometrium between women with preeclampsia and those with preterm labor/delivery (p>0.05).

CONCLUSION

The macrophages at the fetomaternal interface can be dichotomized by CD14 and CD68 immunoreactivity. A gradient of CD14+/CD68+ macrophages was demonstrated between the superficial myometrium and the basal plate regardless of the etiology of preterm birth (preeclampsia or spontaneous preterm labor). The biological function of single positive (CD14-/CD68+) and double positive (CD14+/CD68+) macrophages at the fetomaternal interface remains to be established. The overall findings also suggest that the discrepancies in the literature are due to the varying markers used to detect macrophages and in the anatomical plane of the fetomaternal junction analyzed.

Predictors of resistance to preoperative trastuzumab and vinorelbine for HER2-positive early breast cancer

PURPOSE

To assess pathologic complete response (pCR), clinical response, feasibility, safety, and potential predictors of response to preoperative trastuzumab plus vinorelbine in patients with operable, human epidermal growth factor receptor 2 (HER2)-positive breast cancer.

EXPERIMENTAL DESIGN

Forty-eight patients received preoperative trastuzumab and vinorelbine weekly for 12 weeks. Single and multigene biomarker studies were done in an attempt to identify predictors of response.

RESULTS

Eight of 40 (20%) patients achieved pCR (95% confidence interval, 9-36%). Of 9 additional patients recruited for protocol-defined toxicity analysis, 8 were evaluable; 42 of 48 (88%) patients had clinical response (16 patients, clinical complete response; 26 patients, clinical partial response). T(1) tumors more frequently exhibited clinical complete response (P = 0.05) and showed a trend to exhibit pCR (P = 0.07). Five (13%) patients experienced grade 1 cardiac dysfunction during preoperative treatment. Neither HER2 nor estrogen receptor status changed significantly after exposure to trastuzumab and vinorelbine. RNA profiling identified three top-level clusters by unsupervised analysis. Tumors with extremes of response [pCR (n = 3) versus nonresponse (n = 3)] fell into separate groups by hierarchical clustering. No predictive genes were identified in pCR tumors. Nonresponding tumors were more likely to be T(4) stage (P = 0.02) and express basal markers (P < 0.00001), growth factors, and growth factor receptors. Insulin-like growth factor-I receptor membrane expression was associated with a lower response rate (50% versus 97%; P = 0.001).

CONCLUSIONS

Preoperative trastuzumab plus vinorelbine is active and well tolerated in patients with HER2-positive, operable, stage II/III breast cancer. HER2-overexpressing tumors with a basal-like phenotype, or with expression of insulin-like growth factor-I receptor and other proteins involved in growth factor pathways, are more likely to be resistant to this regimen.

Arrangement and fine structure of collagen fibrils in the decidualized mouse endometrium

The adaptations of the mouse uterus to pregnancy include extensive modifications of the cells and extracellular matrix of the endometrial connective tissue that surround the embryos. Around each implanted embryo this tissue redifferentiates into a transient structure called decidua, which is formed by polygonal cells joined by intercellular junctions. In the mouse, thick collagen fibrils with irregular profile appear in decidualized areas of the endometrium but not in the nondecidualized stroma and interimplantation sites. The fine organization of these thick fibrils has not yet been established. This work was addressed to understand the arrangement and fine structure of collagen fibrils of the decidua of pregnant mice during the periimplantation stage. Major modifications occurred in collagen fibrils that surrounded decidual cells: (1) the fibrils, which were arranged in parallel bundles in nonpregnant animals, became organized as baskets around decidual cells; (2) very thick collagen fibrils with very irregular profiles appeared around decidual cells. Analysis of replicas and serial sections suggests that the thick collagen fibrils form by the lateral aggregation of thinner fibrils to a central fibril resulting in very irregular profile observed in cross sections of thick fibrils. The sum of modifications of the collagen fibrils seem to represent an adaptation of the endometrium to better support the decidual cells while they hold the embryos during the beginning of their development. The deposition of thick collagen fibrils in the decidua may contribute to form a barrier that impedes leukocyte migration within the decidua, preventing immunological rejection of genetically dissimilar embryonic tissues.

Bovine type I collagen inhibits Raw264.7 cell proliferation through phosphoinositide 3-kinase- and mitogen-activated protein kinase-dependent down-regulation of cyclins D1, A and B1

Bovine type I collagen (BIC), which is widely used as a fibrous extracellular matrix component in cell culture models, inhibits the progression of melanoma cell cycle via p27 up-regulation. BIC also induces nitric oxide synthase in macrophages through JunB/AP-1 and NF-kappaB activation. Given the previous observations, this study investigates the effect of BIC on the cell cycle progression and regulatory function of Raw264.7 macrophage cells and the responsible signaling pathways. Cell cycle analysis revealed that BIC completely suppressed proliferation of Raw264.7 cells with inhibition of the percentage of cells in the S phase and the reciprocal decrease in the G0/G1 phase. DNA synthesis was also inhibited by BIC, as evidenced by a decrease in the cellular incorporation of [3H]thymidine. The G1/S arrest induced by BIC was reversed by chemical inhibition of phosphatidylinositol 3-kinase (PI3-kinase) or overexpression of the p85 subunit of PI3-kinase. Either PD98059 or stable transfection with mitogen-activated protein kinase kinase-1 [MKK1(-)] or c-Jun N-terminal kinase 1 [JNK1(-)] also released the cell cycle arrest. Immunoblot analyses revealed that the levels of cyclins D1, A and B1 were partly or completely down-regulated by BIC, but cyclin E, p21 and p27 were minimally changed. Chemical inhibition and dominant negative mutant overexpression experiments revealed that either PI3-kinase inhibition or JNK1(-) transfection prevented the decreases in cyclin D1, A and B1 by BIC, indicating that the PI3-kinase and JNK1 pathways were associated with disruption of the cyclins. The pathway involving MKK1-extracellular signal-regulated kinase-1/2 (ERK1/2) was responsible for the suppression of cyclin A and B1, but not that of cyclin D1. The present study showed that BIC inhibited proliferation of Raw264.7 cells and that the pathways involving PI3-kinase and mitogen-activated protein kinases regulate the cell cycle arrest.

Decidualization of the human endometrial stromal cell: an enigmatic transformation

Changes in human endometrium are essential to allow the establishment of pregnancy. These changes are induced in vivo by progesterone, and include appearance within the tissue of a specific uterine natural killer cell, characterized by an abundant expression of CD56. Changes also occur in the stromal cells, which undergo a characteristic decidualization reaction. Decidualized stromal cells are derived from the fibroblast-like cells within the endometrium, which maintain their progesterone receptors in the presence of progesterone. Prolonged exposure to progesterone induces a rounded cell characterized by release of prolactin and insulin-like growth factor binding protein-1 (IGFBP-1), and expression of tissue factor. Additional changes include the secretion of interleukin (IL)-15, vascular endothelial growth factor, and surface expression of zinc dependent metalloproteinases such as CD10 and CD13. In vitro, elevated intracellular cAMP as well as progesterone is necessary for decidualization. In vivo, these conditions may be provided by progesterone from the corpus luteum, by prostaglandin E, a stimulator of adenyl cyclase, and relaxin, which has recently been shown to be a phosphodiesterase inhibitor. Given the co-distribution of uterine natural killer cells and decidualized stromal cells, a mutual interaction might provide the correct regulatory environment for successful implantation, and penetration of the maternal blood vessels by trophoblastic cells.

Formation of short-lived multinucleated giant cells (MGCS) from cultured gilthead seabream macrophages

Monocytes/macrophages obtained from the head kidney and peritoneal cavity of gilthead seabream (Sparus aurata) were cultured using plates from three different manufacturers, and were maintained under different conditions. The effects on the morphology and fusion of monocytes/macrophages of initial cell loading, removal of non-adherent cells at different times after plating, and addition of serum and antibiotics were evaluated by light microscopy, and transmission (TEM) and scanning (SEM) electron microscopy. Despite variations in adherence, the behaviour and the morphological changes in kidney monocytes/macrophages were similar in all three types of plates. When foetal calf serum (FCS) was added to the incubation medium, most of the cells resembling monocytes/macrophages were connected by cytoplasmic extensions that formed bridges after 24 hr in culture. After 30 hr, the monocytes/macrophages started to fuse, forming multinucleated giant cells (MGCs) which gradually increased in size until the culture was 4-5 days old. After 5 days the MGCs started to die, and after a week most had disappeared from the cultures. Cells incubated with medium without serum showed changes similar to those fed with FCS, but some cells survived for 3 weeks. The addition of fish serum to the medium appeared to accelerate all processes: the monocytes/macrophages and MGCs died after 3 days in culture. Antibiotics had no apparent effect on the cultures. Removal of non-adherent cells at different times after plating did not appear to affect cell fusion. Coating the wells with extracellular matrix proteins reduced adherence but did not inhibit cell fusion. Curiously, not all macrophages fused with MGCs, and, unlike MGCs, these macrophages phagocytosed sheep red blood cells (SRBCs). Peritoneal macrophages also fused and formed MGCs in culture, similarly to kidney cells.

Heterotypic signaling between epithelial tumor cells and fibroblasts in carcinoma formation

Tumors arise from cells that have sustained genetic mutations resulting in deregulation of several of their normal growth-controlling mechanisms. Much of the research concerning the origins of cancer has focused on the genetic mutations within tumor cells, treating tumorigenesis as a cell-autonomous process governed by the genes carried by the tumor cells themselves. However, it is increasingly apparent that the stromal microenvironment in which the tumor cells develop profoundly influences many steps of tumor progression. In various experimental tumor models, the microenvironment affects the efficiency of tumor formation, the rate of tumor growth, the extent of invasiveness, and the ability of tumor cells to metastasize. In carcinomas, the influences of the microenvironment are mediated, in large part, by paracrine signaling between epithelial tumor cells and neighboring stromal fibroblasts. In this review, we summarize recent advances in understanding the paracrine signaling interactions between epithelial cancer cells and associated fibroblasts and examine the effects of these bidirectional interactions on various aspects of carcinoma formation. We note, however, that paracrine signaling between other cell types within the carcinomas, such as endothelial cells and inflammatory cells, may play equally important roles in tumor formation and we will refer to these heterotypic interactions where relevant.

Selective adhesion of macrophages to denatured forms of type I collagen is mediated by scavenger receptors

Macrophages (M&phi;s) are multifunctional immune cells which are involved in the regulation of immune and inflammatory responses, as well as in tissue repair and remodeling. In tissues, M&phi;s reside in areas which are rich in extracellular matrix (ECM), the structural component which also plays an essential role in regulating a variety of cellular functions. A major ECM protein encountered by M&phi;s is type I collagen, the most abundant of the fibril-forming collagens. In this study, the adhesion of RAW 264.7 murine Mphis to native fibrillar, monomeric, and denatured type I collagen was investigated. Using atomic force microscopy, structural differences between fibrillar and monomeric type I collagen were clearly resolved. When cultured on fibrillar type I collagen, Mphis adhered poorly. In contrast, they adhered significantly to monomeric, heat-denatured, or collagenase-modified type I collagen. Studies utilizing anti-beta1 and -beta2 integrin adhesion-blocking antibodies, RGD-containing peptides, or divalent cation-free conditions did not inhibit Mphi; adhesion to monomeric or denatured type I collagen. However, macrophage scavenger receptor (MSR) ligands and anti-MSR antibodies significantly blocked Mphi; adhesion to denatured and monomeric type I collagen strongly suggesting the involvement of the MSR as an adhesion molecule for denatured type I collagen. Further analysis by Western blot identified the MSR as the primary receptor for denatured type I collagen among Mphi; proteins purified from a heat-denatured type I collagen affinity column. These findings indicate that Mphis adhere selectively to denatured forms of type I collagen, but not the native fibrillar conformation, via their scavenger receptors.

Phagocytosis by fresh and cultured human decidual stromal cells: opposite effects of interleukin-1 alpha and progesterone

Flow cytometry and transmission electron microscopy have been employed to show that a proportion of fresh and cultured human decidual stromal cells phagocytose latex particles. Phagocytosis of Escherichia coli by cultured decidual stromal cells was, however, very low. Stimulation of cultured decidual stromal cells with interleukin-1 alpha enhanced phagocytosis of both latex particles and E. coli. In contrast, when decidual stromal cells were cultured with progesterone under decidualizing conditions, phagocytic activity was reduced. These results suggest the existence of an immune-endocrine circuit involving decidual stromal cells.

Expression and function of matrix metalloproteinases and their inhibitors at the maternal-embryonic boundary during mouse embryo implantation

Gelatinase B, a matrix metalloproteinase (MMP) of high specific activity, is highly expressed and activated by mouse blastocysts in culture, and inhibition of this enzyme activity inhibits lysis of extracellular matrix (Behrendtsen, O., Alexander, C. M. and Werb, Z. (1992) Development 114, 447–456). Because gelatinase B expression is linked to invasive potential, we studied the expression of gelatinase B mRNA and protein in vivo, in implanting trophoblast giant cells, and found that it was expressed and activated during colonization of the maternal decidua. mRNAs for several other MMPs (stromelysin-1, stromelysin-3 and gelatinase A) and MMP inhibitors (TIMP-1 and TIMP-2) were expressed in the undifferentiated stroma toward the outside of the decidua, and TIMP-3 mRNA was expressed in primary and some mature decidual cells during their differentiation. Both mRNA and TIMP-3 protein were present at high concentrations transiently, and declined from 6.5 days post coitum onward, as the cells underwent apoptosis during the main period of gelatinase B expression and ectoplacental growth and expansion. To assess the function of MMPs during implantation and decidual development, we either injected a peptide hydroxamate MMP inhibitor into normal mice or studied transgenic mice overexpressing TIMP-1. In both cases, decidual length and overall size were reduced, and the embryo was displaced mesometrially. Embryo orientation was less strictly regulated in inhibitor-treated deciduae than in control deciduae. Morphogenesis and development of oil-induced deciduomas were also slowed in the presence of the inhibitor. We conclude that administration of MMP inhibitors retards decidual remodeling and growth, and we suggest that the MMPs expressed in precursor stromal cells promote their differentiation and expansion.

Cultured human decidual stromal cells express antigens associated with hematopoietic cells

Although decidual stromal cells (DSC) have classically been considered to play a nutritional role during pregnancy, several reports have demonstrated that they can also exert different immune activities. Furthermore, some authors have occasionally found antigens on DSC normally expressed by immune cells. In this study, we isolated and cultured 12 human DSC lines and studied them with immunocytochemistry and flow cytometry using monoclonal antibodies against antigens associated with hematopoietic cells. Decidual stromal cells exhibited a constant phenotype: they were CALLA (CD10)-positive and DR-positive, although the expression of CD45, the leukocyte common antigen, was found to be very weak or negative. We also detected myelomonocytic antigens CD11b (CR3), CD13, CD16 (Fc gamma RIII) and CD36, although DSC lacked CD14, CD15 and CD33. B cell antigens CD20, CD21 (CR3), CD23 (Fc epsilon RII) and CD24 were expressed. DRC-1, an antigen detected on follicular dendritic cells (FDC), was also observed on DSC. When these cells were cultured in the presence of progesterone, they expressed desmin and prolactin (PRL), findings that confirmed their identity as DSC. The phenotype described, together with the immune activities reportedly carried out by DSC, suggest that DSC may play a role in the maternal-fetal immune relationship.

Constitutive secretion of interleukin-6 by human decidual stromal cells in culture. Regulatory effect of progesterone

PROBLEM

Although several studies have demonstrated that decidual stromal cells (DSC) can secrete cytokines in culture, none of these studies documented the purity of the cultures. Since other cells of the decidua, such as macrophages and epithelial cells, also produce cytokines, it is important to ensure purity of the culture so that cytokine production can be ascribed with confidence to DSC.

METHOD

DSC from early human pregnancies were highly purified and maintained in culture. Basal secretion by these cells of IL-6, together with other cytokines considered critical for pregnancy (IL-1 beta, TNF alpha and IFN gamma), was measured with immunological techniques.

RESULTS

We found that DSC in culture produce insignificant quantities of IL-1 beta, TNF alpha and IFN gamma, but appreciable amounts of IL-6. The production of this later cytokine was, however, inhibited by the effect of progesterone.

CONCLUSIONS

Basal production of IL-6 by DSC may be involved in physiological functions at the maternal-fetal interface. Nevertheless, the secretion of this cytokine is regulated by progesterone, probably to prevent excessive production of this cytokine from triggering an inflammatory response that might compromise pregnancy.

Differential expression of laminin, nidogen and collagen IV genes in the midgestation mouse placenta

The distribution of laminin A, B1, B2, nidogen and collagen alpha 1(IV) mRNA was studied in the 12.5-day mouse placenta and uterus. This was compared to the pattern of laminin, nidogen and collagen IV immunoreactivity in the placenta at this time. High levels of B2 mRNA were distributed throughout the decidual layer, compared to lower levels of laminin B1, nidogen and collagen IV. In contrast, laminin B1 and nidogen mRNA were found at very high levels in the trophoblast giant cells and cytotrophoblast. Laminin B2 was much lower in trophoblast cells than in the decidua. Nidogen mRNA levels were low in the decidual cells, but high in endothelial cells lining the placental blood spaces in the decidual layer. Immunofluorescence staining of the placenta showed colocalization of laminin, nidogen and collagen IV in fetal and maternal layers of the placenta. In the antimesometrial area where the uterine epithelium was reforming laminin B1 and B2 mRNA were uniformly distributed between the epithelium and stroma, whereas nidogen and collagen alpha 1(IV) mRNA were only produced by the stromal cells. In all cell types, apart from parietal endoderm cells forming Reichert's membrane, laminin A chain mRNA was very low or absent. These results demonstrate that laminin and nidogen genes are not coordinately expressed in the midgestation mouse placenta. Comparison of the distribution of these mRNAs with collagen alpha 1(IV) mRNA suggests that different regions of the placenta produce specialized extracellular matrices which may contain different ratios of these polypeptides.