Mucin O-glycosylation and pathogen binding ability differ between rainbow trout epithelial sites

Area of Science:

• Aquatic animal health
• Glycobiology
• Fish immunology

Background:

• Mucins are key components of fish mucosal surfaces, playing a vital role in host defense.
• Mucin O-glycans modulate interactions with pathogens, affecting virulence and host attachment.
• Understanding fish mucosal immunity is crucial for developing disease management strategies in aquaculture.

Purpose of the Study:

• To characterize the O-glycosylation patterns of rainbow trout (Oncorhynchus mykiss) mucins from different tissues (gill, skin, pyloric ceca, distal intestine).
• To compare the identified O-glycans with those of other teleost species.
• To investigate the role of mucin O-glycosylation in pathogen binding.

Main Methods:

• O-glycan analysis of mucins isolated from rainbow trout gill, skin, pyloric ceca, and distal intestine.
• Comparative glycomic analysis with existing teleost O-glycome data.
• Bacterial adhesion assays using specific fish pathogens (A. salmonicida, A. hydrophila).

Main Results:

• Fifty-four distinct O-glycans were identified, with varying structures and lengths across tissues.
• Skin mucins exhibited the most acidic and shortest glycans (NeuAcα2-6GalNAc).
• Gill mucins had less acidic glycans (core 1 and 2), while intestinal mucins showed core 5 glycans with NeuAcα2-8NeuAc epitopes.
• Rainbow trout mucins from gill and intestine bound A. salmonicida and A. hydrophila more effectively than skin mucins.

Conclusions:

• Rainbow trout mucin O-glycosylation is tissue-specific, with distinct glycan structures and acidity.
• Skin mucins, with simpler glycans, likely act as a barrier against bacterial adhesion.
• Intestinal mucins, with complex glycans, may function in pathogen trapping and removal.
• These findings provide insights into fish mucosal defense mechanisms relevant to aquaculture health.