Mosquito C-type lectins maintain gut microbiome homeostasis

Area of Science:

• Microbiology
• Immunology
• Vector Biology

Background:

• Host-microbe interactions are crucial for maintaining homeostasis.
• Mammalian commensal bacteria manipulate host immunity, but invertebrate strategies are less understood.
• Mosquito gut microbiome's interaction with host immunity requires further investigation.

Purpose of the Study:

• To elucidate the mechanisms by which insect symbiotic microbiomes overcome host immune responses.
• To investigate the role of C-type lectins (mosGCTLs) in mosquito gut microbiome homeostasis.
• To understand how mosquito gut bacteria evade antimicrobial peptides (AMPs).

Main Methods:

• Investigated the function of Aedes aegypti C-type lectins (mosGCTLs) in facilitating bacterial colonization.
• Assessed the reliance of gut microbial flora maintenance on mosGCTL expression in A. aegypti.
• Examined the effect of silencing mosGCTL orthologues in Culex pipiens pallens on gut commensal survival.

Main Results:

• Aedes aegypti mosGCTLs were found to facilitate colonization by multiple bacterial strains.
• Maintenance of the mosquito gut microbial flora depends on mosGCTL expression.
• Silencing mosGCTL in Culex pipiens pallens impaired gut commensal bacteria survival.
• Mosquito gut microbiome stimulates mosGCTL expression, which coats bacteria and counteracts AMP activity.

Conclusions:

• Mosquito gut microbiome utilizes mosGCTLs to evade the host's antimicrobial peptide (AMP) immune response.
• This mechanism, involving mosGCTLs coating bacteria, is essential for achieving gut homeostasis in insects.
• The findings reveal a novel strategy for symbiotic microbiome survival against host immunity in invertebrates.