Otto Loewi Research Centre, Division of Pharmacology, Medical University of Graz, Universitätsplatz 4, A-8010 Graz; phone: +43-316-385 74112, fax: +43-316-380 9645, ✉ e-mail
Inflammation, immune response, endothelium, macrophages, cytokines, prostaglandins, adhesion, chemotaxis, placenta, umbilical cord
Accumulation of leukocytes in tissues is a key feature of inflammation and a major determinant of tissue damage. Pregnancy is an immunological challenge for mother and fetus, and numerous immune cells take part in the development of the decidua. Particularly macrophages are thought to be crucial in maintaining an immune-tolerant environment in the semi-allogeneic setting of trophoblast invasion (1)
The main focus of our laboratory is to define the mechanisms that govern the trafficking of leukocytes from bone marrow, where they are generated, to the inflammatory site and their subsequent activation in tissue, where they may become harmful. Chemoattractants, their receptors, and adhesion molecules both on the leukocytes and the endothelial side, play crucial roles in the multi-step process of leukocyte infiltration by facilitating leukocyte locomotion and activation, and are thus considered as promising therapeutic targets in various inflammatory conditions. Conversely, several endogenous mediators exist that down-regulate the responsiveness of leukocytes and might hence exert potent anti-inflammatory effects. When supplemented pharmaceutically, these mediators might likewise open novel therapeutic avenues. Among others we have elucidated the opposing roles of two cyclooxygenase (COX) products, prostaglandin (PG) E2 and D2 in leukocyte trafficking in human and animal models, and have characterized their receptors at the molecular and pharmacological level. While we have shown that its receptor EP4 is a negative regulator of eosinophil and neutrophil trafficking, and endothelial, thrombocyte and macrophage activation (2, 3), we have also revealed a novel role for PGD2 and its receptors DP1 and DP2 as potent activators of eosinophils, basophils and macrophages (4, 5).
It has been suggested previously that PGE2 and PGD2 might play distinct roles in pathological conditions of pregnancy, but how these prostaglandins contribute to the regulation of leukocyte function in the developing decidua and, even more, how responses to PGE2 and PGD2 of immune cells in the placenta are altered in different gestational pathologies has not been addressed in detail. Currently we are elucidating the expression patterns and levels of enzymes involved in prostaglandin synthesis (COX isoforms, PGE and PGD synthases) and receptors for PGE2 and PGD2 in placental tissue. We hypothesize that an imbalance of anti-inflammatory PGE2 effects and pro-inflammatory PGD2 actions might contribute to complications in pregnancy, such as hypertension, pre-eclampsia or preterm labor. We will characterize these alterations on the cellular (e. g. endothelial cells, macrophages) and tissue level (i. e. placenta).
Fig. 1: Full-term human placenta stained for D-type prostanoid (DP)1 receptor. The syncytiotrophoblast, surrounding the chorionic villi and forming part of the placental barrier shows strong staining for the DP1 receptor. The arrow indicates a Hofbauer-cell (fetal macrophage) also showing positive staining for DP1. Red asterisks show fetal capillaries inside the villus and the blue asterisk marks the intravillous space (maternal side). Magnification 100× (A) and 600× (B)
Fig. 2: Full-term human placenta stained for D-type prostanoid (DP)2 receptor. The syncytiotrophoblast, surrounding the chorionic villi and forming part of the placental barrier shows staining for the DP2 receptor. The arrow indicates a Hofbauer-cell (fetal macrophage) and the arrowhead points to a fetal leukocyte inside a capillary, both showing positive staining for DP2. Red asterisks show fetal capillaries inside the villus and the blue asterisk marks the intravillous space filled with maternal erythrocytes (maternal side). Magnification 100× (A) and 600× (B).
Bayer AG, Germany; AstraZeneca AB, Sweden; Protaffin GmbH, Graz, Austria.
The laboratory of Ákos Heinemann has a long-standing expertise in the field of leukocyte biology and pharmacology, but also in hemodynamic regulation and vascular biology. Studies are routinely carried out both with primary cells isolated from humans and cells from animal sources, complemented with cell lines for transfection / silencing experiments. The group comprises two post-doctoral fellows, three technicians and five PhD students. Various techniques are being used for a detailed analysis of leukocyte and endothelial cell function, and the group has considerable experience with in vivo models of leukocyte trafficking and inflammation. All the required equipment is available at the institute, including animal and cell-culture facilities, radionuclide laboratory, flow cytometry, real-time PCR systems, fluorescence plate reader, tissue processing and fluorescence microscopy, and a microscopy system to study cell-to-cell interaction and thrombus formation under flow conditions. The group has also access to video-tracking of leukocyte locomotion and laser-scanning microscopy at the CMR.
DP-iDP students will be trained in immunology and will receive insights in the regulation of leukocyte and endothelial function, in particular trafficking and activation, and how this process impacts on inflammation and tissue damage. In addition, they will get background knowledge on current concepts of anti-inflammatory therapies and where demand for further research exists. Students will learn how to analyze signaling properties of G protein-coupled receptors and characterize respective ligands in specific pharmacological and functional immunological assays. The acquired methodologies will comprise isolation and culturing of cells from blood and tissues, flow cytometry, RNA techniques including siRNA gene knock-down, immunoprecipitation and western blot, and laser-scanning microscopy. The students will also be trained to characterize and quantitate specific lipid subclasses by mass spectroscopy (GC-MS, LC-MS).