Gonadotropin-releasing hormone-regulated chemokine expression in human placentation.

Placental expression of gonadotropin-releasing hormone (GnRH)-I and II, as well as their cognate receptor, coincides with a period of extensive remodeling of the maternal-fetal interface, near the end of the first trimester of pregnancy. To further define the role of GnRH in human placentation, we performed a microarray screen of HTR-8/SVneo trophoblasts to identify GnRH-regulated genes and their roles in placentation. This screen revealed that GnRH regulates the expression of four angiogenic chemokines: CXCL2, CXCL3, CXCL6, and CXCL8. The microarray data were subsequently confirmed by an extensive Q-PCR time-course analysis. CXCL8, a representative chemokine, was selected for further analysis and shown to be strongly expressed by trophoblasts at the maternal-fetal interface of the human placenta, as well as to accumulate in a GnRH-dependent manner in trophoblast-conditioned media in culture. Trophoblasts were subsequently shown to recruit lymphocytes (Jurkat T cells and primary peripheral blood T and uterine natural killer cells) in chemotaxis assays and this was shown to be GnRH dependent. Furthermore, this recruitment was shown to occur via the release of CXCR1/CXCR2 interacting chemokines, such as the CXCLs investigated in this study. This novel regulation of chemokines by GnRH signaling demonstrates the role of GnRH in regulating the recruitment of lymphocytes to the decidua and the possibility of a direct effect on spiral artery remodeling via the release of proangiogenic chemokines and secondary effects via release of angiogenic factors by recruited lymphocytes.

Impact of thrombophilia screening on venous thromboembolism management practices.

BACKGROUND: It is unclear whether thrombophilia testing provides any further information on risk of recurrence or guidance in management of patients with a first episode of idiopathic venous thromboembolism (VTE). Furthermore, after the introduction to clinical practice of clinical prediction rules, thrombophilia screening could be less relevant in anticoagulation decision making. We assessed the potential impact of thrombophilia screening on the decision of maintaining anticoagulation beyond the initially planned anticoagulation period in patients with an unprovoked VTE, before and after the introduction of a clinical prediction rule into practice. PATIENTS/METHODS: We conducted a single center, retrospective cohort study of consecutive patients with a diagnosis of unprovoked VTE, including a study period of 12years. Two groups were compared, before and after 2008. RESULTS: We included 1033 patients of which 85.2% were tested for thrombophilia and 26.2% were identified with any thrombophilia. A similar proportion of patients continued on anticoagulation after 6months (54.1% vs 57.1%, respectively). The proportion of patients continuing anticoagulation based on the thrombophilia screen remained small (13.9% vs 12.7%, respectively). Continuing anticoagulation beyond the initial period planned resulted in a 75% risk reduction in VTE recurrence, independent of the presence of thrombophilia (HR 0.25, 95% CI 0.12-0.55; P<0.001). CONCLUSIONS: Thrombophilia screening continues to have little relevance in clinical decision making for anticoagulation. Prolonging anticoagulation beyond 6months in an at-risk population decreased the risk of VTE recurrence regardless of their thrombophilia status.

Regulation of GPR54 signaling by GRK2 and {beta}-arrestin.

Kisspeptin and its receptor, GPR54, are major regulators of the hypothalamic-pituitary-gonadal axis as well as regulators of human placentation and tumor metastases. GPR54 is a G(q/11)-coupled G protein-coupled receptor (GPCR), and activation by kisspeptin stimulates phosphatidy linositol 4, 5-biphosphate hydrolysis, Ca(2+) mobilization, arachidonic acid release, and ERK1/2 MAPK phosphorylation. Physiological evidence suggests that GPR54 undergoes agonist-dependent desensitization, but underlying molecular mechanisms are unknown. Furthermore, very little has been reported on the early events that regulate GPR54 signaling. The lack of information in these important areas led to this study. Here we report for the first time on the role of GPCR serine/threonine kinase (GRK)2 and beta-arrestin in regulating GPR54 signaling in human embryonic kidney (HEK) 293 cells, a model cell system for studying the molecular regulation of GPCRs, and genetically modified MDA MB-231 cells, an invasive breast cancer cell line expressing about 75% less beta-arrestin-2 than the control cell line. Our study reveals that in HEK 293 cells, GPR54 is expressed both at the plasma membrane and intracellularly and also that plasma membrane expression is regulated by cytoplasmic tail sequences. We also demonstrate that GPR54 exhibits constitutive activity, internalization, and association with GRK2 and beta- arrestins-1 and 2 through sequences in the second intracellular loop and cytoplasmic tail of the receptor. We also show that GRK2 stimulates the desensitization of GPR54 in HEK 293 cells and that beta-arrestin-2 mediates GPR54 activation of ERK1/2 in MDA-MB-231 cells. The significance of these findings in developing molecular-based therapies for treating certain endocrine-related disorders is discussed.