Biased G protein-coupled receptor ligands engage subsets of the receptor signals normally stimulated by unbiased agonists. However, it is unclear whether ligand bias can elicit differentiated pharmacology in vivo. Here, we describe the discovery of a potent, selective ␤-arrestin biased ligand of the angiotensin II type 1 receptor. TRV120027 (Sar-Arg-Val-Tyr-Ile-His-Pro-DAla-OH) competitively antagonizes angiotensin II-stimulated G protein signaling, but stimulates ␤-arrestin recruitment and activates several kinase pathways, including p42/44 mitogenactivated protein kinase, Src, and endothelial nitric-oxide synthase phosphorylation via ␤-arrestin coupling. Consistent with ␤-arrestin efficacy, and unlike unbiased antagonists, TRV120027 increased cardiomyocyte contractility in vitro. In rats, TRV120027 reduced mean arterial pressure, as did the unbiased antagonists losartan and telmisartan. However, unlike the unbiased antagonists, which decreased cardiac performance, TRV120027 increased cardiac performance and preserved cardiac stroke volume. These striking differences in vivo between unbiased and ␤-arrestin biased ligands validate the use of biased ligands to selectively target specific receptor functions in drug discovery.

The active form of vitamin D, 1,25-dihydroxyvitamin D(3) (1,25[OH](2)D(3)) is a potent immunomodulatory seco-steroid. We have demonstrated that several components of vitamin D metabolism and signaling are strongly expressed in human uterine decidua from first trimester pregnancies, suggesting that locally produced 1,25(OH)(2)D(3) may exert immunosuppressive effects during early stages of gestation. To investigate this further, we used primary cultures of human decidual cells from first and third trimester pregnancies to demonstrate expression and activity of the enzyme that catalyzes synthesis of 1,25(OH)(2)D(3), 1alpha-hydroxylase (CYP27B1). Synthesis of 1,25(OH)(2)D(3) was higher in first trimester decidual cells (41 +/- 11.8 fmoles/h/mg protein) than in third trimester cells (8 +/- 4.4 fmoles/h/mg protein; P < 0.05). Purification of decidual cells followed by quantitative RT-PCR analysis showed that CYP27B1 was expressed by both CD10(+VE) stromal-enriched and CD10(-VE) stromal-depleted cells, with higher levels of mRNA in first trimester pregnancies. Expression of CYP27B1 correlated with TLR4 and IDO. Functional responses to 1,25(OH)(2)D(3) were studied using CD56(+VE) natural killer (NK) cells isolated from first trimester decidua. Decidual NK cells treated with 1,25(OH)(2)D(3) or precursor 25-hydroxyvitamin D(3) (25OHD(3)) for 28 h showed decreased synthesis of cytokines, such as granulocyte-macrophage colony stimulating factor 2 (CSF2), tumor necrosis factor, and interleukin 6, but increased expression of mRNA for the antimicrobial peptide cathelicidin antimicrobial peptide. These data indicate that human decidual cells are able to synthesize active 1,25(OH)(2)D(3), particularly in early gestation, and this may act in an autocrine/paracrine fashion to regulate both acquired and innate immune responses at the fetal-maternal interface.

The active form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D), is a potent inducer of the antimicrobial protein cathelicidin, CAMP (LL37). In macrophages this response is dependent on intracrine synthesis of 1,25(OH)2D from precursor 25-hydroxyvitamin D (25OHD), catalyzed by the enzyme 25-hydroxyvitamin D-1alpha-hydroxylase (CYP27B1). In view of the fact that trophoblastic cells also express abundant CYP27B1, we postulated a similar intracrine pathway for induction of CAMP in the placenta. Analysis of placenta explants, primary cultures of human trophoblast, and the 3A trophoblastic cell line treated with 1,25(OH)2D (1–100 nM) revealed dose-dependent induction of CAMP similar to that observed with primary cultures of human macrophages. Also consistent with macrophages, induction of trophoblastic CAMP was enhanced via intracrine conversion of 25OHD to 1,25(OH)2D. However, in contrast to macrophages, induction of CAMP by vitamin D in trophoblasts was not enhanced by costimulation with Toll-like receptor ligands, such as lipopolysaccharide. Despite this, exposure to vitamin D metabolites significantly enhanced antibacterial responses in trophoblastic cells: 3A cells infected with Escherichia coli showed decreased numbers of bacterial colony-forming units compared with vehicle-treated controls when treated with 25OHD (49.6% ± 10.9%) or 1,25(OH)2D (45.4% ± 9.2%), both P < 0.001. Treatment with 25OHD (1–100 nM) or 1,25(OH)2D (0.1–10 nM) also protected 3A cells against cell death following infection with E. coli (13.6%–26.9% and 22.3%–40.2% protection, respectively). These observations indicate that 1,25(OH)2D can function as an intracrine regulator of CAMP in trophoblasts, and may thus provide a novel mechanism for activation of innate immune responses in the placenta.

Background: There is significant concern about the worldwide migration of nursing professionals from low-income countries to rich ones, as nurses are lured to fill the large number of vacancies in upper-income countries. This study explores the views of nursing students in Uganda to assess their views on practice options and their intentions to migrate.