Immune Function and Oxidative Stress in Aquatic Organisms

Aquatic organisms rely predominantly on innate immune mechanisms to defend against pathogens, with key roles for barrier tissues, phagocytic cells and soluble effectors such as lysozyme and complement proteins. Reactive oxygen species (ROS) are generated both as signalling molecules and as microbicidal agents during phagocytosis, but excessive ROS can damage lipids, proteins and nucleic acids, leading to oxidative stress. Antioxidant defences—comprising enzymatic systems such as superoxide dismutase, catalase and glutathione peroxidase, alongside non-enzymatic antioxidants—restore redox balance. Environmental challenges including temperature fluctuations, chemical pollutants and salinity shifts can disrupt this balance, impairing immune competence and increasing disease susceptibility. Understanding the interplay between immune activation and oxidative homeostasis is critical for sustainable aquaculture, conservation of wild stocks and assessment of ecosystem health under global change.

Research from Nature Portfolio

Dietary chrysophanic acid administered to Catla catla fingerlings enhanced both non-specific immune parameters and the transcription of immune-related genes in head-kidney leukocytes when challenged with Aeromonas hydrophila. At an optimal dose, fish exhibited increased phagocytic and respiratory burst activities, elevated production of hydrogen peroxide and nitric oxide and upregulation of toll-like receptors, pro-inflammatory cytokines (such as TNF-α) and major histocompatibility complex transcripts. Transcriptomic profiling revealed coordinated regulation of signalling pathways that link oxidative burst to gene expression, highlighting a mechanistic basis for dietary immunostimulants in fish disease resilience.

Immune Function and Oxidative Stress in Aquatic Organisms publication trend

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

Technical terms

Reactive oxygen species (ROS): Short-lived oxygen-derived molecules produced during metabolism and immune responses; can kill pathogens but also inflict cellular damage if unchecked.

Oxidative stress: A state in which ROS production exceeds antioxidant capacity, leading to molecular and cellular injury.

Antioxidant enzymes: Proteins such as superoxide dismutase, catalase and glutathione peroxidase that catalyse the detoxification of ROS.

Phagocytosis: The process by which specialised immune cells engulf and digest invading microorganisms.

Cytokines: Small signalling proteins (e.g., interleukins, tumour necrosis factor) that orchestrate immune cell activation and inflammation.

Myeloperoxidase: An enzyme in phagocytic cells that generates potent oxidants to destroy internalised pathogens.

References

1. The Eco-Immunological Relevance of the Anti-Oxidant Response in Invasive Molluscs. Antioxidants (2023).
2. Evaluating Silymarin Extract as a Potent Antioxidant Supplement in Diazinon-Exposed Rainbow Trout: Oxidative Stress and Biochemical Parameter Analysis. Toxics (2023).
3. Temperature fluctuation alters immuno-antioxidant response and enhances the susceptibility of Oreochromis niloticus to Aeromonas hydrophila challenge. Aquaculture International (2023).
4. Effect of chrysophanic acid on immune response and immune genes transcriptomic profile in Catla catla against Aeromonas hydrophila. Scientific Reports (2021).