Wed Oct 21 // Dr. Peter Mergaert // Institute of Integrative Biology of the Cell, Centre National de la Recherche Scientifique

Dr. Peter Mergaert
​Centre National de la Recherche Scientifique
Role of antimicrobial peptides and the ROS-producing enzyme Duox in insect gut symbiosis

Most animals harbor a gut microbiota that consists of potentially pathogenic, commensal and mutualistic microorganisms. In insects, antimicrobial peptides (AMPs) and the reactive oxygen species (ROS)-producing enzyme “Dual oxidase” (Duox) are the central regulators of gut mucosal immunity. They antagonize pathogenic bacteria and maintain gut homeostasis. However, the non-specific harmful activity of AMPs and ROS on microorganisms raises the question about the role of AMPs and Duox in the maintenance of mutualistic gut symbionts. In my seminar, I will highlight how AMPs and Duox control the establishment of a specific gut symbiosis in the bean bug Riptortus pedestris, which harbors in a symbiotic compartment of the midgut the mutualistic bacterium Burkholderia insecticola.
We have demonstrated that symbiosis-specific as well as immunity-specific AMPs are produced massively during B. insecticola infection of the gut and that resistance to these AMPs is crucial for the capacity of the bacterium to colonize the gut. On the other hand, and contrarily to our initial expectation, we found that Duox-dependent ROS did not directly contribute to epithelial immunity in the midgut in response to B. insecticola or to pathogenic bacteria. Instead, we demonstrated that Duox is essential for symbiosis and the colonization of the gut by the aerobic B. insecticola by mediating the formation of a respiratory network enveloping the gut.