Innate Immune Responses in Aquatic Organisms

Aquatic organisms rely on an evolutionarily ancient defence system known as innate immunity, which operates without prior exposure to pathogens. This multilayered network comprises physical barriers such as mucosal surfaces, cellular effectors including phagocytic cells and natural killer–like cells, and humoral components such as complement proteins, antimicrobial peptides and lysozyme. Pathogen recognition receptors detect conserved microbial signatures and trigger intracellular signalling cascades—most notably the NF-κB and MAPK pathways—culminating in the release of pro-inflammatory cytokines and reactive oxygen species. Concurrently, antioxidant enzymes such as superoxide dismutase and catalase modulate oxidative stress and prevent tissue damage. Innate immunity in fish, crustaceans and molluscs exhibits both common and taxon-specific features, reflecting adaptation to diverse aquatic habitats. Understanding these mechanisms has broad implications, from mitigating infectious disease outbreaks in aquaculture to preserving wild populations under environmental stress. Practical applications include the development of immunostimulatory feed supplements, probiotic treatments and bioactive compounds designed to enhance non-specific defence and reduce reliance on antibiotics, thereby improving animal welfare and sustainable production.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Innate Immune Responses in Aquatic Organisms publication trend

The graph below shows the total number of articles in innate immune responses in aquatic organisms across all publications each year (not limited to Nature Index journals).

Technical terms

Pathogen recognition receptors (PRRs): Molecules on immune cells that detect conserved microbial components and initiate innate responses.

Lysozyme: An enzyme that degrades bacterial cell walls, serving as a key antimicrobial agent in mucosal secretions and haemolymph.

Complement system: A cascade of plasma proteins that promotes opsonisation, inflammation and direct pathogen lysis.

Pro-inflammatory cytokines: Signalling proteins such as tumour necrosis factor-α and interleukin-1β that amplify inflammatory responses.

Oxidative stress markers: Enzymes including superoxide dismutase and catalase that neutralise reactive oxygen species and protect tissues.

Tight junction proteins: Structural components like claudins and zonula occludens-1 that maintain epithelial barrier integrity in the intestine.

References

1. The P4’ Peptide‐Carrying Bacillus subtilis in Cottonseed Meal Improves the Chinese Mitten Crab Eriocheir sinensis Innate Immunity, Redox Defense, and Growth Performance. Aquaculture Nutrition (2024).
2. Therapeutic uses and applications of bovine lactoferrin in aquatic animal medicine: an overview. Veterinary Research Communications (2023).
3. Evaluation of Alpha-Ketoglutarate Supplementation on the Improvement of Intestinal Antioxidant Capacity and Immune Response in Songpu Mirror Carp (Cyprinus carpio) After Infection With Aeromonas hydrophila. Frontiers in Immunology (2021).