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A role for variable region-containing chitin-binding proteins (VCBPs) in host gut-bacteria interactions
Larry J Dishaw1, Stefano Giacomelli, Daniela Melillo
1Department of Pediatrics, University of South Florida College of Medicine and University of South Florida/All Children's Hospital Children's Research Institute, St Petersburg, FL 33701, USA.
Summary
Chitin-binding proteins (VCBPs) in Ciona, a primitive chordate, bind bacteria and enhance immune cell phagocytosis. These findings suggest ancient origins for immune recognition elements involved in host-microbe interactions.
Area of Science:
- Immunology
- Evolutionary Biology
- Marine Biology
Background:
- Adaptive immunity relies on molecules like immunoglobulins and T-cell receptors with variable domains for specificity.
- These variable (V) domains are crucial for immune recognition in jawed vertebrates.
Purpose of the Study:
- To investigate the structure and function of V region-containing chitin-binding proteins (VCBPs) in the urochordate Ciona.
- To explore the role of VCBPs in innate immunity and host-microbe interactions within the gut.
Main Methods:
- VCBPs were identified and characterized in Ciona, encoded by four loci (VCBPA-VCBPD).
- Expression patterns in epithelial and immune cells were analyzed.
- Binding to bacterial surfaces was assessed using immunogold analysis.
- The effect of VCBP-C and V domains on bacterial phagocytosis by granular amoebocytes was tested in vitro.
Main Results:
- VCBPs are secreted into the gut lumen and directly bind to bacterial surfaces.
- Affinity-purified and recombinant VCBP-C, as well as V domain constructs, enhanced bacterial phagocytosis by granular amoebocytes.
- VCBP expression was observed in gut epithelial cells, lamina propria, and circulating blood cells.
Conclusions:
- VCBPs represent a novel class of immune molecules in Ciona with direct antimicrobial functions.
- The findings suggest that key elements of immune recognition, particularly those involving V domains and host-microbe dialogue, have ancient evolutionary origins predating jawed vertebrates.
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