Syk phosphorylation – a gravisensitive step in macrophage signalling

Cell Communication and Signaling

Research

Ruth Hemmersbach¹  Sonja Brungs¹  Waldemar Kolanus² 

[1] Biomedical Research Institute of Aerospace Medicine, German Aerospace Center (DLR), Linder Hoehe, 51147, Koeln, Germany;Molecular Immunology, LIMES Institute, University of Bonn, Carl-Troll Str. 31, 53115, Bonn, Germany;

关键词: Host defence;    Microgravity;    Syk;    Clinostat;    NF-κB;    Macrophage;    ROS signalling;   

DOI  :  10.1186/s12964-015-0088-8

 received in 2014-10-01, accepted in 2015-01-20,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundThe recognition of pathogen patterns followed by the production of reactive oxygen species (ROS) during the oxidative burst is one of the major functions of macrophages. This process is the first line of defence and is crucial for the prevention of pathogen-associated diseases. There are indications that the immune system of astronauts is impaired during spaceflight, which could result in an increased susceptibility to infections. Several studies have indicated that the oxidative burst of macrophages is highly impaired after spaceflight, but the underlying mechanism remained to be elucidated. Here, we investigated the characteristics of reactive oxygen species production during the oxidative burst after pathogen pattern recognition in simulated microgravity by using a fast-rotating Clinostat to mimic the condition of microgravity. Furthermore, spleen tyrosine kinase (Syk) phosphorylation, which is required for ROS production, and the translocation of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) to the nucleus were monitored to elucidate the influence of altered gravity on macrophage signalling.ResultsSimulated microgravity leads to significantly diminished ROS production in macrophages upon zymosan, curdlan and lipopolysaccharide stimulation. To address the signalling mechanisms involved, Syk phosphorylation was examined, revealing significantly reduced phosphorylation in simulated microgravity compared to normal gravity (1 g) conditions. In contrast, a later signalling step, the translocation of NF-κB to the nucleus, demonstrated no gravity-dependent alterations.ConclusionsThe results obtained in simulated microgravity show that ROS production in macrophages is a highly gravisensitive process, caused by a diminished Syk phosphorylation. In contrast, NF-κB signalling remains consistent in simulated microgravity. This difference reveals that early signalling steps, such as Syk phosphorylation, are affected by microgravity, whereas the lack of effects in later steps might indicate adaptation processes. Taken together, this study clearly demonstrates that macrophages display impaired signalling upon pattern recognition when exposed to simulated microgravity conditions, which if verified in real microgravity this may be one reason why astronauts display higher susceptibility to infections.

【 授权许可】

CC BY   
© Brungs et al.; licensee BioMed Central. 2015