| Affiliation: | 1.Department of Machine Design, Engineering Design and Product Development, Institute of Mechanical Engineering,Otto-von-Guericke-University Magdeburg,Magdeburg,Germany;2.Institute of Anatomy, Faculty of Medicine,University of Zurich,Zurich,Switzerland;3.Gravitational Biology, Biomedical Science Support Center, Institute of Aerospace Medicine,German Aerospace Center (DLR),Koeln,Germany;4.EADS Astrium, TEB 22 Payload Engineering,Claude Dornier Strasse,Friedrichshafen,Germany;5.Department Biology II,LMU München,Planegg-Martinsried,Germany;6.Study Team SAHC, Institute of Aerospace Medicine,German Aerospace Center (DLR),Linder Hoehe,Germany;7.Chair of Proteomics and Bioanalytics,TU München,Freising,Germany;8.Laboratory of Molecular Immunology, Life and Medical Sciences (LIMES) Institute,University of Bonn,Bonn,Germany;9.Study Group “Magdeburger Arbeitsgemeinschaft für Forschung unter Raumfahrt- und Schwerelosigkeitsbedingungen” (MARS),Otto-von-Guericke-University Magdeburg,Magdeburg,Germany;10.Zurich Center for Integrative Human Physiology (ZIHP),University of Zurich,Zurich,Switzerland |
| Abstract: | Gravity has been a constant force throughout the Earth’s evolutionary history. Thus, one of the fundamental biological questions is if and how complex cellular and molecular functions of life on Earth require gravity. In this study, we investigated the influence of gravity on the oxidative burst reaction in macrophages, one of the key elements in innate immune response and cellular signaling. An important step is the production of superoxide by the NADPH oxidase, which is rapidly converted to H2O2 by spontaneous and enzymatic dismutation. The phagozytosis-mediated oxidative burst under altered gravity conditions was studied in NR8383 rat alveolar macrophages by means of a luminol assay. Ground-based experiments in “functional weightlessness” were performed using a 2 D clinostat combined with a photomultiplier (PMT clinostat). The same technical set-up was used during the 13th DLR and 51st ESA parabolic flight campaign. Furthermore, hypergravity conditions were provided by using the Multi-Sample Incubation Centrifuge (MuSIC) and the Short Arm Human Centrifuge (SAHC). The results demonstrate that release of reactive oxygen species (ROS) during the oxidative burst reaction depends greatly on gravity conditions. ROS release is 1.) reduced in microgravity, 2.) enhanced in hypergravity and 3.) responds rapidly and reversible to altered gravity within seconds. We substantiated the effect of altered gravity on oxidative burst reaction in two independent experimental systems, parabolic flights and 2D clinostat / centrifuge experiments. Furthermore, the results obtained in simulated microgravity (2D clinorotation experiments) were proven by experiments in real microgravity as in both cases a pronounced reduction in ROS was observed. Our experiments indicate that gravity-sensitive steps are located both in the initial activation pathways and in the final oxidative burst reaction itself, which could be explained by the role of cytoskeletal dynamics in the assembly and function of the NADPH oxidase complex. |
