Babcock Daniel T, Brock Amanda R, Fish Greg S, Wang Yan, Perrin Laurent, Krasnow Mark A, Galko Michael J
Department of Biochemistry and Molecular Biology, University of Texas Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
Proc Natl Acad Sci U S A. 2008 Jul 22;105(29):10017-22. doi: 10.1073/pnas.0709951105. Epub 2008 Jul 16.
Insects have an open circulatory system in which the heart pumps blood (hemolymph) into the body cavity, where it directly bathes the internal organs and epidermis. The blood contains free and tissue-bound immune cells that function in the inflammatory response. Here, we use live imaging of transgenic Drosophila larvae with fluorescently labeled blood cells (hemocytes) to investigate the circulatory dynamics of larval blood cells and their response to tissue injury. We find that, under normal conditions, the free cells rapidly circulate, whereas the tissue-bound cells are sessile. After epidermal wounding, tissue-bound cells around the wound site remain sessile and unresponsive, whereas circulating cells are rapidly recruited to the site of damage by adhesive capture. After capture, these cells distribute across the wound, appear phagocytically active, and are subsequently released back into circulation by the healing epidermis. The results demonstrate that circulating cells function as a surveillance system that monitors larval tissues for damage, and that adhesive capture, an important mechanism of recruitment of circulating cells to inflammatory sites in vertebrates, is shared by insects and vertebrates despite the vastly different architectures of their circulatory systems.
昆虫具有开放式循环系统，其中心脏将血液（血淋巴）泵入体腔，血液在体腔中直接浸润内部器官和表皮。血液中含有游离的和与组织结合的免疫细胞，它们在炎症反应中发挥作用。在这里，我们利用对具有荧光标记血细胞（血细胞）的转基因果蝇幼虫进行实时成像，来研究幼虫血细胞的循环动态及其对组织损伤的反应。我们发现，在正常情况下，游离细胞快速循环，而与组织结合的细胞则固定不动。表皮受伤后，伤口部位周围与组织结合的细胞仍固定不动且无反应，而循环细胞则通过黏附捕获迅速被招募到损伤部位。捕获后，这些细胞分布在伤口处，表现出吞噬活性，随后被愈合的表皮释放回循环中。结果表明，循环细胞起到监测系统的作用，监测幼虫组织是否受损，并且黏附捕获这一将循环细胞招募到脊椎动物炎症部位的重要机制，在昆虫和脊椎动物中是共有的，尽管它们的循环系统结构差异巨大。
