Reactive oxygen species-mediated immunity against Leishmania mexicana and Serratia marcescens in the sand phlebotomine fly Lutzomyia longipalpis.
Phlebotomine sand flies are the vectors of medically important Leishmania. The Leishmania protozoa reside in the sand fly gut, but the nature of the immune response to the presence of Leishmania is unknown. Reactive oxygen species (ROS) are a major component of insect innate immune pathways regulating gut-microbe homeostasis. Here we show that the concentration of ROS increased in sand fly midguts after they fed on the insect pathogen Serratia marcescens but not after feeding on the Leishmania that uses the sand fly as a vector. Moreover, the Leishmania is sensitive to ROS either by oral administration of ROS to the infected fly or by silencing a gene that expresses a sand fly ROS-scavenging enzyme. Finally, the treatment of sand flies with an exogenous ROS scavenger (uric acid) altered the gut microbial homeostasis, led to an increased commensal gut microbiota, and reduced insect survival after oral infection with S. marcescens. Our study demonstrates a differential response of the sand fly ROS system to gut microbiota, an insect pathogen, and the Leishmania that utilize the sand fly as a vehicle for transmission between mammalian hosts.
Vector Group, Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom.
Hector
H
Diaz-Albiter
Mauricio R V
MR
Sant'Anna
Fernando A
FA
Genta
Rod J
RJ
Dillon
D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology; D002374:Catalase / Q000145:classification / Q000235:genetics / Q000378:metabolism; D005260:Female; D041981:Gastrointestinal Tract / Q000378:metabolism / Q000382:microbiology / Q000469:parasitology; D055786:Gene Knockout Techniques; D054884:Host-Pathogen Interactions / Q000187:drug effects / Q000276:immunology; D006861:Hydrogen Peroxide / Q000378:metabolism; D007109:Immunity / Q000187:drug effects / Q000276:immunology*; D019476:Insect Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D007303:Insect Vectors / Q000276:immunology / Q000382:microbiology / Q000469:parasitology; D007894:Leishmania mexicana / Q000276:immunology* / Q000502:physiology; D008969:Molecular Sequence Data; D054464:Peroxiredoxins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D011576:Psychodidae / Q000201:enzymology / Q000235:genetics / Q000276:immunology*; D017382:Reactive Oxygen Species / Q000276:immunology* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012706:Serratia marcescens / Q000276:immunology* / Q000502:physiology; D013482:Superoxide Dismutase / Q000145:classification / Q000235:genetics / Q000378:metabolism; D014527:Uric Acid / Q000008:administration & dosage / Q000494:pharmacology
D000975:Antioxidants; D019476:Insect Proteins; D017382:Reactive Oxygen Species; D014527:Uric Acid; D006861:Hydrogen Peroxide; D054464:Peroxiredoxins; D002374:Catalase; D013482:Superoxide Dismutase