Leitão Alexandre B, Arunkumar Ramesh, Day Jonathan P, Hanna Nancy, Devi Aarathi, Hayes Matthew P, Jiggins Francis M
Department of Genetics, University of Cambridge, Cambridge, UK.
Champalimaud Foundation, Lisbon, Portugal.
BMC Biol. 2024 Apr 22;22(1):89. doi: 10.1186/s12915-024-01886-1.
Innate immune responses can be activated by pathogen-associated molecular patterns (PAMPs), danger signals released by damaged tissues, or the absence of self-molecules that inhibit immunity. As PAMPs are typically conserved across broad groups of pathogens but absent from the host, it is unclear whether they allow hosts to recognize parasites that are phylogenetically similar to themselves, such as parasitoid wasps infecting insects.
Parasitoids must penetrate the cuticle of Drosophila larvae to inject their eggs. In line with previous results, we found that the danger signal of wounding triggers the differentiation of specialized immune cells called lamellocytes. However, using oil droplets to mimic infection by a parasitoid wasp egg, we found that this does not activate the melanization response. This aspect of the immune response also requires exposure to parasite molecules. The unidentified factor enhances the transcriptional response in hemocytes and induces a specific response in the fat body.
We conclude that a combination of danger signals and the recognition of nonself molecules is required to activate Drosophila's immune response against parasitic insects.
固有免疫反应可由病原体相关分子模式（PAMPs）、受损组织释放的危险信号或抑制免疫的自身分子缺失所激活。由于PAMPs通常在广泛的病原体群体中保守存在而在宿主中不存在，尚不清楚它们是否能让宿主识别与自身在系统发育上相似的寄生虫，如感染昆虫的寄生蜂。
寄生蜂必须穿透果蝇幼虫的表皮来产卵。与先前结果一致，我们发现创伤的危险信号会触发称为扁平细胞的特殊免疫细胞的分化。然而，使用油滴模拟寄生蜂卵感染，我们发现这不会激活黑化反应。免疫反应的这一方面还需要接触寄生虫分子。这个未确定的因子增强了血细胞中的转录反应，并在脂肪体中诱导特定反应。
我们得出结论，激活果蝇针对寄生昆虫的免疫反应需要危险信号和非自身分子识别的结合。
