Drosophila melanogaster as a model to study innate immune memory

Abstract

Over the last decades, research regarding innate immune responses has gained increasing importance. A growing body of evidence supports the notion that the innate arm of the immune system could show memory traits. Such traits are thought to be conserved throughout evolution and provide a survival advantage. Several models are available to study these mechanisms. Among them, we find the fruit fly, Drosophila melanogaster. This non-mammalian model has been widely used for innate immune research since it naturally lacks an adaptive response. Here, we aim to review the latest advances in the study of the memory mechanisms of the innate immune response using this animal model.

IMD-mediated innate immune priming increases Drosophila survival and reduces pathogen transmission

“…There is now substantial evidence of diverse priming responses occurring within the same invertebrate life stage (larvae or adults), across life stages (from larvae to adults), or even between generations (parents to offspring) [12–15]. The survival benefit of priming has been observed in a range of arthropod taxa, including Dipterans: fruit flies [16], mosquitoes [17]; Coleopterans: flour beetles [14,18]; Lepidopterans: the greater wax-moth [19]; Hymenopterans: bumblebee [9]; Crustaceans: water fleas [20] and Arachnids: spiders and scorpions [21].…”

“…The observation of immune priming in invertebrates underlines the importance of whole organism research in immunity in lieu of a purely mechanistic approach to immunology, highlighting that the same phenomenology can originate in very different mechanisms [6,12]. Determining the mechanisms of invertebrate immune priming has often proved challenging, but has generally revealed a great diversity of ways in which invertebrates may enhance their immune responses upon reinfection[12,25,26].…”

“…The observation of immune priming in invertebrates underlines the importance of whole organism research in immunity in lieu of a purely mechanistic approach to immunology, highlighting that the same phenomenology can originate in very different mechanisms [6,12]. Determining the mechanisms of invertebrate immune priming has often proved challenging, but has generally revealed a great diversity of ways in which invertebrates may enhance their immune responses upon reinfection[12,25,26]. In Drosophila , the priming response during infection with the gram-positive bacterial pathogen Streptococcus pneumoniae was shown to be dependent on haemocytes and phagocytosis, while the Toll-pathway - the main pathway involved in clearance of gram-positive bacteria - was shown to be insufficient for successful priming [16].…”

“…These differences in immune physiology resulted in the long-standing assumption that invertebrates should not be capable of immune memory, though this view was clearly at odds with empirical evidence from several invertebrate hostpathogen systems [4][5][6]. Work in recent decades has revealed that insects also possess a form of immune memory, known generally as "immune priming", where low doses of an infectious pathogen, or even an inactivated pathogen, can lead to increased survival upon reinfection [7][8][9][10][11][12].…”

Using Drosophila melanogaster as a suitable platform for drug discovery from natural products in inflammatory bowel disease

“…Drosophila does not have the acquired immune system found in mammals, and solely depends on general mechanisms of innate immunity for its immune defenses ( Lemaitre and Hoffmann, 2007 ). However, flies have high conserved features for innate immunity with mammals, such as immune cascades, signal transduction pathways, and transcriptional regulators ( Arch et al, 2022 ).…”