The influence of the phase of the estrous cycle on sheep endometrial tissue response to lipopolysaccharide.

The effect of lipopolysaccharide on ovine endometrial tissue was examined at estrus (follicular phase) and during the luteal phase. Endometrial tissues were cultured with 0, 1, or 10 microg/mL lipopolysaccharide. After 24 h, culture supernates were harvested and analyzed for PGF2alpha, PGE2, 6-keto-PGF1alpha, thromboxane B2 (TXB2), and cysteinyl-leukotrienes (leukotrienes) using EIA.

Endothelial vasodilator production by uterine and systemic arteries. IV. Cyclooxygenase isoform expression during the ovarian cycle and pregnancy in sheep.

Uterine artery endothelial production of the potent vasodilator, prostacyclin, is greater in pregnant versus nonpregnant sheep and in whole uterine artery from intact versus ovariectomized ewes. We hypothesized that uterine artery cyclooxygenase (COX)-1 and/or COX-2 expression would be elevated during pregnancy (high estrogen and progesterone) and the follicular phase of the ovarian cycle (high estrogen/low progesterone) as compared to that in luteal phase (low estrogen/high progesterone) or in ovariectomized (low estrogen and progesterone) ewes. Uterine and systemic (omental) arteries were obtained from nonpregnant luteal-phase (LUT; n = 10), follicular-phase (FOL; n = 11), and ovariectomized (OVEX; n = 10) sheep, as well as from pregnant sheep (110-130 days gestation; term = 145 +/- 3 days; n = 12).

The influence of reproductive phase on lipopolysaccharide stimulation of prostacyclin production and cyclooxygenase-2 protein concentrations in reproductive and systemic arteries of the sheep.

Cyclooxygenase, the enzyme that converts arachidonate to prostaglandins, plays a regulatory role in vasodilation under normal and pathological conditions. Studies were conducted to determine the effects of reproductive phase and lipopolysaccharide (LPS) on production of PGI2 and amounts of cyclooxygenase protein in uterine, mammary, mesenteric, and renal arteries. Arteries were collected from ewes during the follicular (Day 0 = estrus) or luteal (Day 10) phase of the estrous cycle and were cultured in the presence of LPS.

Cellular source in ewes of prostaglandin-endoperoxide synthase-2 in uterine arteries following stimulation with lipopolysaccharide.

Prostaglandin-endoperoxide synthase (PTGS) (also known as cyclooxygenase) converts arachidonic acid into several prostaglandins, many of which have roles in vasodilation and vasoconstriction under normal and pathological conditions. There are two isoforms of PTGS: PTGS-1 and PTGS-2; PTGS-1 is constitutively expressed in many tissues and is believed to be involved in the homeostatic maintenance of the body. In contrast, PTGS-2 is believed to have a "differentiative" role in the cells and is highly inducible during inflammation and in response to lipopolysaccharide (LPS).

Endothelial vasodilator production by uterine and systemic arteries. III. Ovarian and estrogen effects on NO synthase.

During the follicular phase of the ovarian cycle, when the local estrogen-to-progesterone ratio is elevated, uterine blood flow is elevated. This vasodilatory response is reproduced by exogenous 17beta-estradiol (E2beta) administration via a nitric oxide (NO)-mediated mechanism. We hypothesized that endogenous ovarian estrogen and exogenous E2beta treatment elevate expression of endothelial cell-derived NO synthase (eNOS) in uterine, but not in systemic, arteries.

Matrix metalloproteinases-2 and -9, and tissue inhibitor of metalloproteinases-1 of the sheep placenta during the last third of gestation.

Uteroplacental and fetoplacental blood flows increase dramatically during the last third of gestation. Therefore, angiogenesis and tissue remodelling may regulate placental growth. On days 110, 120, 130, and 142 (term= 145+/-3; n=5 ewes/day) of gestation, sheep placentae were separated into maternal (caruncular and intercaruncular) and fetal (cotyledonary and intercotyledonary) components; tissues were minced and cultured (24 h) and media were analysed for gelatinase activity and for tissue inhibitor of metalloproteinases-1 (TIMP-1) protein.

Estrogen and lipopolysaccharide stimulation of prostacyclin production and the levels of cyclooxygenase and nitric oxide synthase in ovine uterine arteries.

Several enzymes play a role in vasodilation, including cyclooxygenase, which converts arachidonic acid into prostaglandins, and nitric oxide synthase, which converts arginine to citrulline and yields nitric oxide. The effects of endogenous and exogenous estrogen and lipopolysaccharide on uterine artery production of prostacyclin, and levels of cyclooxygenase and nitric oxide synthase were examined. Uterine arteries collected from ewes during the follicular (Day -1 to 0, Day 0 = estrus) or luteal (Day 10) phase were treated in vitro with lipopolysaccharide.

Report of the Second Equine Leucocyte Antigen Workshop, Squaw valley, California, July 1995.

The final assignment of antibody clusters for leucocyte antigens and immunoglobulins, as described in detail in Sections 3 and 4, is summarized in Table 4. Together with other mAbs developed outside of ELAW II (Table 9) this pool of reagents represent a powerful array of tools for the study of equine immunity. The Second Equine Leucocyte Antigen Workshop made considerable advances in pursuing the objectives of establishing the specificities of mAbs and achieving consensus on the nomenclature for equine leucocyte and immunoglobulin molecules.

The equine immune response to endometrial cups.

Out of all the areas of comparative immunological study in the horse, the field of reproductive immunology has proven to be one of the most fertile and exciting. Maternal immunological interactions with the fetus involve a set of events which prevent maternal rejection of trophoblastic tissue invading the uterus, and at the same time control this invasion to regulate growth and prevent damage to maternal tissues. Unique features of equine placentation make it exceptionally well-suited to studying these immunological interactions.

Expression of basic fibroblast growth factor, endothelial mitogenic activity, and angiotensin II type-1 receptors in the ovine placenta during the third trimester of pregnancy.

To evaluate expression of basic fibroblast growth factor (FGF), endothelial mitogenic activity, and angiotensin II type-1 receptors (AT1r), as well as the role of angiotensin II (ANG II) in regulating basic FGF production/secretion, placentae were obtained from ewes on Days 110, 120, 130, and 142 of pregnancy and were separated into fetal cotyledonary (COT) and intercotyledonary (ICOT), as well as maternal caruncular (CAR) and intercaruncular (ICAR) components. Using immunohistochemistry, basic FGF and AT1r were found for the most part to be colocalized in all placental components, primarily in epithelium, stroma, endothelium, and vascular smooth muscle. Changes in basic FGF levels in placental explant-conditioned media were observed in fetal, but not maternal, components.

Positive selection of EqCD8+ precursors increases equine lymphokine-activated killing.

Lymphokine activated killing (LAK) is an example of natural cytotoxicity, and as such is a critical means of defense against diseases such as viral infection and neoplasia. Despite this important role, the specific molecular interactions involved in LAK or other forms of natural cytotoxicity are only partially understood. In some species, cells capable of mediating natural cytotoxicity express the CD8 molecule, although no specific role has been demonstrated for CD8 in non-MHC restricted cytotoxicity.

Susceptibility of equine chorionic girdle cells to lymphokine-activated killer cell activity.

Problem: Equine chorionic girdle cells are a subpopulation of highly invasive trophoblast cells that attach and invade the uterine epithelium on Day 35 (Day 0 = day of ovulation). These invading chorionic girdle cells form endometrial cups that are associated with a marked local maternal leukocytic response that may result in the demise of the cups at Day 120 of pregnancy. Once endometrial cups become established in the uterine wall they do not express MHC antigens, and therefore may only be susceptible to non-MHC restricted cytotoxic cells.

Expression of major histocompatibility complex antigen and timing of invasion by equine chorionic girdle cells cultured on Matrigel.

Chorionic girdle cells are a highly invasive subpopulation of trophoblastic cells of the horse conceptus that adhere to the uterine epithelium and begin to invade the endometrium on Days 34-36 (Day 0 = day of ovulation). Just prior to and during invasion (Days 32-36), chorionic girdle cells express high levels of major histocompatibility complex (MHC) I, but expression of this antigen decreases by Days 40-45 and is lost by Day 55. The mechanisms involved in the control of chorionic girdle cell invasion and altered MHCI expression over time are not known.

Metalloproteinase activity has a role in equine chorionic girdle cell invasion.

Chorionic girdle cells are a highly invasive subpopulation of trophoblast cells of the equine conceptus. By Day 35 (Day 0 = day of ovulation), cells of the chorionic girdle adhere to the uterine epithelium and begin to invade the endometrial wall. Invasive cells must attach to extracellular matrix proteins, secrete proteinases capable of degrading matrix, and migrate through the degraded matrix; invasion is largely dependent on the proteinase activity of the cells.