Background Prostaglandin (PG) D2 is an early-phase mediator in inflammation, but its action and the roles of the 2 D-type prostanoid receptors (DPs) DP1 and DP2 (also called chemoattractant ...receptor–homologous molecule expressed on TH 2 cells) in regulating macrophages have not been elucidated to date. Objective We investigated the role of PGD2 receptors on primary human macrophages, as well as primary murine lung macrophages, and their ability to influence neutrophil action in vitro and in vivo. Methods In vitro studies, including migration, Ca2+ flux, and cytokine secretion, were conducted with primary human monocyte-derived macrophages and neutrophils and freshly isolated murine alveolar and pulmonary interstitial macrophages. In vivo pulmonary inflammation was assessed in male BALB/c mice. Results Activation of DP1 , DP2 , or both receptors on human macrophages induced strong intracellular Ca2+ flux, cytokine release, and migration of macrophages. In a murine model of LPS-induced pulmonary inflammation, activation of each PGD2 receptor resulted in aggravated airway neutrophilia, tissue myeloperoxidase activity, cytokine contents, and decreased lung compliance. Selective depletion of alveolar macrophages abolished the PGD2 -enhanced inflammatory response. Activation of PGD2 receptors on human macrophages enhanced the migratory capacity and prolonged the survival of neutrophils in vitro . In human lung tissue specimens both DP1 and DP2 receptors were located on alveolar macrophages along with hematopoietic PGD synthase, the rate-limiting enzyme of PGD2 synthesis. Conclusion For the first time, our results show that PGD2 markedly augments disease activity through its ability to enhance the proinflammatory actions of macrophages and subsequent neutrophil activation.
Recent clinical studies have shown a strong correlation between in vitro cholesterol efflux capacity (CEC) and cardiovascular disease prevalence (1) and incidence (2,3) that seems to be independent ...of high-density lipoprotein cholesterol (HDL-C) levels. ...our results suggest that CEC is not a prognostic cardiovascular risk marker in patients with CKD.
Background Increased vascular permeability is a fundamental characteristic of inflammation. Substances that are released during inflammation, such as prostaglandin (PG) E2 , can counteract vascular ...leakage, thereby hampering tissue damage. Objective In this study we investigated the role of PGE2 and its receptors in the barrier function of human pulmonary microvascular endothelial cells and in neutrophil trafficking. Methods Endothelial barrier function was determined based on electrical impedance measurements. Neutrophil recruitment was assessed based on adhesion and transendothelial migration. Morphologic alterations are shown by using immunofluorescence microscopy. Results We observed that activation of E-type prostanoid (EP) 4 receptor by PGE2 or an EP4-selective agonist (ONO AE1-329) enhanced the barrier function of human microvascular lung endothelial cells. EP4 receptor activation prompted similar responses in pulmonary artery and coronary artery endothelial cells. These effects were reversed by an EP4 antagonist (ONO AE3-208), as well as by blocking actin polymerization with cytochalasin B. The EP4 receptor–induced increase in barrier function was independent of the classical cyclic AMP/protein kinase A signaling machinery, endothelial nitric oxide synthase, and Rac1. Most importantly, EP4 receptor stimulation showed potent anti-inflammatory activities by (1) facilitating wound healing of pulmonary microvascular endothelial monolayers, (2) preventing junctional and cytoskeletal reorganization of activated endothelial cells, and (3) impairing neutrophil adhesion to endothelial cells and transendothelial migration. The latter effects could be partially attributed to reduced E-selectin expression after EP4 receptor stimulation. Conclusion These data indicate that EP4 agonists as anti-inflammatory agents represent a potential therapy for diseases with increased vascular permeability and neutrophil extravasation.
Background Enhanced eosinophil migration from the blood into the tissue is a hallmark of allergic diseases. Prostaglandin (PG) I2 is the major prostanoid released by endothelial cells. Mice deficient ...in PGI2 receptors (IPs) show exaggerated eosinophilic inflammation in response to allergen. Objective We set out to determine the role of PGI2 in eosinophil trafficking. Methods Human lung microvascular endothelial cells and purified human eosinophils were used to study adhesion and transendothelial migration. Morphologic studies were performed with fluorescence microscopy. Results PGI2 markedly attenuated the migration of eosinophils through cell-free filters but had no effect on neutrophil migration. The inhibitory effect of PGI2 on eosinophils was prevented by the IP antagonist Cay10441 and the adenylyl cyclase inhibitor SQ22536. Similarly, PGI2 prevented the adhesion of eosinophils to fibronectin and the rapid upregulation and activation of the adhesion molecule CD11b. IP expression on eosinophils was confirmed by means of flow cytometry and Western blotting. Furthermore, when endothelial cells were treated with the COX inhibitor diclofenac to abolish PGI2 production, adhesion of eosinophils to endothelial monolayers and subsequent transendothelial migration were markedly enhanced. Similarly, the IP antagonist enhanced eosinophil adhesion to endothelial cells. Inhibition of PGI2 biosynthesis decreased the electrical resistance of endothelial monolayers and compromised the texture of adherent junctions, as visualized by means of VE-cadherin and F-actin staining. Conclusion We propose that endothelium-derived PGI2 might be fundamental for the maintenance of the endothelial barrier function against infiltrating cells. These results suggest that selective IP agonists might have beneficial effects in allergic inflammation.
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