Charroux Bernard, Royet Julien
Institut de Biologie du Développement de Marseille Luminy, Unité Mixte de Recherche 6216, Centre National de la Recherche Scientifique, Université de la Méditerrannée Aix-Marseille II, 13288 Marseille Cedex 9, France.
Proc Natl Acad Sci U S A. 2009 Jun 16;106(24):9797-802. doi: 10.1073/pnas.0903971106. Epub 2009 May 29.
Drosophila hemocytes have strong phagocytic capacities and produce antimicrobial peptides (AMPs). However, the precise role of blood cells during immune responses and developmental processes has only been studied using indirect means. To overcome this limitation, we generated plasmatocyte-depleted flies by specifically overexpressing the proapoptotic protein Hid into plasmatocytes. Unexpectedly, these plasmatocyte-depleted animals have a normal larval and pupal development and do not exhibit any obvious defect after birth. Remarkably, plasmatocyte-depleted adults show a strong susceptibility to infections by various microorganisms, although activation of systemic AMP gene transcription via the Toll and immune deficiency (IMD) pathways is wild-type. Our data show that this susceptibility, which correlates with overproliferation of bacteria, is likely due to the absence of phagocytosis. We also demonstrate that during larval stages, plasmatocytes play an essential role in mediating AMP production by the fat body after oral bacterial infection. Finally, we show that plasmatocytes are involved in immune surveillance during pupal development, because they prevent bacterial infection that causes pupal lethality.
果蝇血细胞具有强大的吞噬能力并能产生抗菌肽（AMPs）。然而，血细胞在免疫反应和发育过程中的精确作用仅通过间接方法进行了研究。为了克服这一局限性，我们通过在浆细胞中特异性过表达促凋亡蛋白Hid来生成浆细胞缺失的果蝇。出乎意料的是，这些浆细胞缺失的动物幼虫和蛹发育正常，出生后也没有表现出任何明显缺陷。值得注意的是，浆细胞缺失的成虫对各种微生物感染表现出高度易感性，尽管通过Toll和免疫缺陷（IMD）途径激活系统性AMPs基因转录是野生型的。我们的数据表明，这种与细菌过度增殖相关的易感性可能是由于缺乏吞噬作用。我们还证明，在幼虫阶段，浆细胞在口服细菌感染后介导脂肪体产生AMPs中起重要作用。最后，我们表明浆细胞参与蛹发育过程中的免疫监视，因为它们能预防导致蛹死亡的细菌感染。
