Robert N. Taylor

Preeclampsia: An endothelial cell disorder

Despite intense study preeclampsia remains enigmatic and a major cause of maternal and fetal morbidity and mortality. Most investigative efforts have focused on the hypertensive component of this disorder with reduced attention given to other equally important characteristics. Increased sensitivity to pressor agents and activation of the coagulation cascade occur early in the course of preeclampsia, often antedating clinically recognizable disease. Inasmuch as endothelial cell injury reduces the synthesis of vasorelaxing agents, increases the production of vasoconstrictors, impairs synthesis of endogenous anticoagulants, and increases procoagulant production, these cells are likely to be implicated in the pathophysiology of preeclampsia. Indeed, evidence of endothelial cell injury is provided by the most characteristic morphologic lesion of preeclampsia, glomerular endotheliosis. Additional support for this hypothesis is derived from reports that indicate increased levels of circulating fibronectin (which can be released from injured endothelial cells) and increased factor VIII antigen present in the blood of preeclamptic women. More recently, direct evidence of activities that injure endothelial cells in vitro and increase the contractile sensitivity of isolated vessels has been presented. We propose that poorly perfused placental tissue releases a factor(s) into the systemic circulation that injuries endothelial cells. The changes initiated by endothelial cell injury set in motion a dysfunctional cascade of coagulation, vasoconstriction, and intravascular fluid redistribution that results in the clinical syndrome of preeclampsia.

Immunobiology of endometriosis

OBJECTIVE To provide a review of the humoral and cellular immunology of endometriosis and to discuss the rationale for future approaches to diagnosis and treatment. DESIGN Literature survey. RESULT(S) Defective immunosurveillance in women who are destined to develop endometriosis may allow for the survival of ectopic endometrial tissue. The evidence includes endometrial cell resistance to apoptosis, perhaps through the secretion of proteins that interfere with implant recognition and/or FasL expression by stromal cells, inducing apoptosis of Fas-bearing immune cells. Although the immune response may be defective, aspects of it clearly are enhanced in endometriosis, as is seen by the generalized polyclonal B-cell autoimmune activation and secretion of immune proteins. Several cytokines, chemokines, and growth factors (including vascular growth factors) are increased in women with endometriosis. CONCLUSION(S) A complex network of locally produced cytokines modulate the growth and inflammatory behavior of ectopic endometrial implants. Proinflammatory proteins from endometriotic lesions and associated immune cells contribute to the enhanced inflammatory reaction associated with endometriosis that subserves the survival of these lesions instead of leading to their demise.

Ovarian steroid regulation of vascular endothelial growth factor in the human endometrium: implications for angiogenesis during the menstrual cycle and in the pathogenesis of endometriosis.

The human endometrium undergoes a complex process of vascular and glandular proliferation, differentiation, and regeneration with each menstrual cycle in preparation for implantation. Vascular endothelial growth factor (VEGF) is an endothelial cell-specific angiogenic protein that appears to play an important role in both physiological and pathological neovascularization. To investigate whether VEGF may regulate human endometrial angiogenesis, we examined VEGF messenger ribonucleic acid (mRNA) and protein throughout the menstrual cycle and studied the regulation of VEGF by reproductive steroids in isolated human endometrial cells. By ribonuclease protection analysis, VEGF mRNA increased relative to early proliferative phase expression by 1.6-,2.0-, and 3.6-fold in midproliferative, late proliferative, and secretory endometrium, respectively. In histological sections, VEGF mRNA and protein were localized focally in glandular epithelial cells and more diffusely in surrounding stroma, with greatest VEGF expression in secretory endometrium. Consistent with these in vivo results, the treatment of isolated human endometrial cells with estradiol (E2), medroxyprogesterone acetate (MPA), or E2 plus MPA significantly increased VEGF mRNA expression over the control value by 3.1-, 2.8-, and 4.7-fold, respectively. The VEGF response to E2 was rapid, with steady state levels of VEGF mRNA reaching 85% maximum 1 h after the addition of steroid. E2 also caused a 46% increase in secreted VEGF protein, and the combination of E2 and MPA caused an 18% increase. VEGF expression in endometriosis, an angiogenesis-dependent, estrogen-sensitive disease was similar to that seen in eutopic endometrium. Peritoneal fluid concentrations of VEGF were significantly higher in women with moderate to severe endometriosis than in women with minimal to mild endometriosis or no disease. VEGF, therefore, may be important in both physiological and pathological angiogenesis of human endometrium, as it is an estrogen-responsive angiogenic factor that varies throughout the menstrual cycle and is elevated in women with endometriosis.

Expression Profiling of Endometrium from Women with Endometriosis Reveals Candidate Genes for Disease-Based Implantation Failure and Infertility

Endometriosis is clinically associated with pelvic pain and infertility, with implantation failure strongly suggested as an underlying cause for the observed infertility. Eutopic endometrium of women with endometriosis provides a unique experimental paradigm for investigation into molecular mechanisms of reproductive dysfunction and an opportunity to identify specific markers for this disease. We applied paralleled gene expression profiling using high-density oligonucleotide microarrays to investigate differentially regulated genes in endometrium from women with vs. without endometriosis. Fifteen endometrial biopsy samples (obtained during the window of implantation from eight subjects with and seven subjects without endometriosis) were processed for expression profiling on Affymetrix Hu95A microarrays. Data analysis was conducted with GeneChip Analysis Suite, version 4.01, and GeneSpring version 4.0.4. Nonparametric testing was applied, using a P value of 0.05, to assess statistical significance. Of the 12,686 genes analyzed, 91 genes were significantly increased more than 2-fold in their expression, and 115 genes were decreased more than 2-fold. Unsupervised clustering demonstrated down-regulation of several known cell adhesion molecules, endometrial epithelial secreted proteins, and proteins not previously known to be involved in the pathogenesis of endometriosis, as well as up-regulated genes. Selected dysregulated genes were randomly chosen and validated with RT-PCR and/or Northern/dot-blot analyses, and confirmed up-regulation of collagen alpha2 type I, 2.6-fold; bile salt export pump, 2.0-fold; and down-regulation of N-acetylglucosamine-6-O-sulfotransferase (important in synthesis of L-selectin ligands), 1.7-fold; glycodelin, 51.5-fold; integrin alpha2, 1.8-fold; and B61 (Ephrin A1), 4.5-fold. Two-way overlapping layer analysis used to compare endometrial genes in the window of implantation from women with and without endometriosis further identified three unique groups of target genes, which differ with respect to the implantation window and the presence of disease. Group 1 target genes are up-regulated during the normal window of implantation but significantly decreased in women with endometriosis: IL-15, proline-rich protein, B61, Dickkopf-1, glycodelin, N-acetylglucosamine-6-O-sulfotransferase, G0S2 protein, and purine nucleoside phosphorylase. Group 2 genes are normally down-regulated during the window of implantation but are significantly increased with endometriosis: semaphorin E, neuronal olfactomedin-related endoplasmic reticulum localized protein mRNA and Sam68-like phosphotyrosine protein alpha. Group 3 consists of a single gene, neuronal pentraxin II, normally down-regulated during the window of implantation and further decreased in endometrium from women with endometriosis. The data support dysregulation of select genes leading to an inhospitable environment for implantation, including genes involved in embryonic attachment, embryo toxicity, immune dysfunction, and apoptotic responses, as well as genes likely contributing to the pathogenesis of endometriosis, including aromatase, progesterone receptor, angiogenic factors, and others. Identification and validation of selected genes and their functions will contribute to uncovering previously unknown mechanism(s) underlying implantation failure in women with endometriosis and infertility, mechanisms underlying the pathogenesis of endometriosis and providing potential new targets for diagnostic screening and intervention.

Preeclampsia is associated with a serum factor cytotoxic to human endothelial cells

Preeclampsia occurs in 7% to 10% of pregnancies and is a leading cause of morbidity for mothers and their infants. Intensive investigation has failed to reveal the cause of the multiple organ dysfunction characteristic of this disorder, which abates completely with delivery. However, several observations suggest that endothelial cell dysfunction is a central pathophysiologic event. We report that serum from preeclamptic women is cytotoxic to endothelial cells in vitro. Consistent with the reversal of the clinical condition after delivery, cytotoxic activity in serum of preeclamptic women is reduced after 24 to 48 hours post partum. In contrast, cytotoxic activity of serum from normal pregnant women increases after delivery.

Angiogenic Factors in Endometriosis

Abstract: Similar to tumor metastases, endometriotic implants require neovascularization to establish, grow, and invade. The peritoneal environment is ideally suited to provide a proangiogenic milieu. Nevertheless, endometriotic lesions are found only in a minority of reproductive‐age women (∼10%) with retrograde menstruation. In this paper, we review the major cytokines, growth factors, steroid hormones, and eicosanoids responsible for angiogenesis in endometriosis. We postulate that interference with angiogenic principles expressed in the peritoneum may constitute novel therapeutic opportunities for the prevention, amelioration, or treatment of pelvic endometriosis.

Peritoneal fluid concentrations of the cytokine RANTES correlate with the severity of endometriosis

OBJECTIVE Endometriosis is a common gynecologic disorder in which the concentration and activation of peritoneal macrophages are increased. The goal of this study was to quantify pelvic fluid concentrations of two cytokines involved in macrophage recruitment and activation. STUDY DESIGN A case-control study of women undergoing pelvic surgery was conducted by collecting peritoneal fluid from 12 women without evidence of endometriosis (controls), 12 with mild, and 12 with moderate to severe endometriosis. Concentrations of RANTES and interferon gamma, soluble cytokines known to recruit and activate macrophages, were quantified by enzyme-linked immunosorbent assays. RESULTS Pelvic fluid concentrations of RANTES are elevated in women with endometriosis and the levels correlate with the severity of disease. By contrast, concentrations of interferon gamma appear unaffected by the presence of or severity of endometriosis. CONCLUSION The findings indicate that RANTES, a cytokine with potent chemotactic activity for human monocytes, may play an important role in the recruitment of peritoneal macrophages in endometriosis.

Angiogenesis and Macrophage Activation in Endometriosis

Recent studies suggest that the symptoms associated with endometriosis are the result of local peritoneal inflammation. Increased concentrations of activated pelvic macrophages and lymphocytes and the elevated levels of specific cytokines and growth factors reviewed above support this hypothesis. The precise roles of these soluble factors are currently unknown, but we propose that a complex network of endometrial cytokines are normally regulated by hormones produced during the ovulatory cycle. Ectopic endometrial implants also are subject to these same endocrine cues. The secretion of these proinflammatory proteins by endometriosis lesions into the peritoneal microenvironment appears to cause a recruitment of capillaries and activated inflammatory cells to the implant. Future therapeutic strategies directed to ameliorate the inflammatory reaction associated with endometriosis should not ignore the likely physiological actions of many of the same bioactive molecules in normal eutopic endometrial function.

Review: Immunobiology of Preeclampsia

Preeclampsia has been recognized clinically since the time of Hippocrates: however its etiology and pathophysiology remain enigmatic. This pregnancy‐specific syndrome typically presents in late pregnancy as hypertension, edema, and proteinuria. Investigations over the past 15 years have revealed that preeclampsia is associated with abnormal placentation, reduced placental perfusion, endothelial cell dysfunction, and systemic vasospasm. Since it occurs more commonly in Primigravidae and in women with underlying collagen‐vascular diseases, an immunological component has long been suspected. Increased prevalence in high‐order and molar pregnancies and those associated with increased placental mass suggests that trophoblastic volume and fetal antigen load are correlated with the syndrome. Epidemiological reports indicate that the prevalence of preeclampsia is decreased in women who received heterologous blood transfusions, practiced oral sex, or when a long period of cohabitation preceded an established pregnancy. Conversely, the use of condoms as a primary mode of contraception is associated with a higher risk of preeclampsia. These studies suggest that prior exposure to foreign or paternal antigens imparts a protection against the likelihood of developing preeclampsia. Clinical evidence of cellular and humoral immune dysfunction is associated with the syndrome. Fibrin and complement deposition and “foam” cells in atherosis lesions resemble the histopathology of renal allograft rejection. Relative T‐cell, natural killer cell, and neutrophil activation have been reported in preeclampsia and circulating cytokines and antiphospholipid antibodies are more prevalent in preeclamptic than in normal pregnant women. These abnormalities are consistent with the systemic endothelial cell dysfunction that has been postulated as a pathophysiological feature of preeclampsia. While such associations do not prove causality, they suggest testable hypotheses for continued basic and clinical investigation of this major complication of human pregnancy.

Sera From Preeclamptic Women Specifically Activate Human Umbilical Vein Endothelial Cells In Vitro: Morphological and Biochemical Evidence

ABSTRACT: Endothelial cell dysfunction could explain many of the pathophysiological changes observed in preeclampsia. Markers of endothelial cell activation including increased circulating Von Willebrand factor (VWF) and cellular fibronectin (cFN) antedate clinically evident disease. We have therefore proposed that alteration of endothelial cell function by circulating agent(s) produced by the placenta initiates the clinical syndrome. This hypothesis predicts that there are a factor(s) in the blood of women with preeclampsia that are capable of altering endothelial cell function. We and others have examined in vitro interactions of maternal serum and endothelial cells to test this hypothesis. Our initial report indicating increased release of [51Cr]chromate from human umbilical vein endothelial cells (HUVE) suggested a lethal, lytic effect of serum from preeclamptic women. However, more specific indicators of endothelial cell structure and function do not support such a nonspecific effect. The morphology of HUVE was minimally altered after exposure to sera of preeclamptic women, and the entry of propidium iodide entry into cells, a sensitive indicator of membrane integrity, also was not increased. These findings, in combination with the increased expression of mRNA for platelet‐derived growth factor (PDGF), suggest endothelial cell activation rather than cell death in response to sera from preeclamptic women. Comparison of the effects of endotoxin and sera from preeclamptic women also supports the specificity of this response. Whereas endotoxin strikingly increased VWF on the surface of HUVE and tissue factor activity in conditioned media while minimally increasing cFN, preeclamptic sera increased cFN but had no demonstrable effect on VWF or tissue factor activity. Thus, under the conditions of our in vitro assays, sera from preeclamptic women are not diffusely toxic but rather act selectively on specific activation pathways.