Systemic immune responses do not affect significant immune responses in the skin

Area of Science:

• Aquatic immunology
• Fish health
• Immunology

Background:

• Fish skin mucus is crucial for defense against aquatic pathogens.
• Local skin immunity can trigger systemic immune responses via cytokines.
• The relationship between systemic and skin immunity post-pathogen invasion is not fully understood.

Purpose of the Study:

• To investigate the interplay between systemic and skin immune responses in fish.
• To determine if skin immune responses are activated following systemic immune responses after pathogen challenge.

Main Methods:

• Intraperitoneal injection of formalin-killed cells (FKC) of Vibrio anguillarum in fish.
• Analysis of systemic inflammatory responses in the spleen.
• Gene expression analysis in fish skin, focusing on immune-related factors and hemoglobin subunits.

Main Results:

• Systemic inflammatory responses were detected in the spleen post-injection.
• No significant changes in immune-related gene expression were observed in the skin.
• A significant increase in hemoglobin subunit gene expression was noted in the skin, suggesting extravascular erythrocyte infiltration.

Conclusions:

• Systemic immune activation following Vibrio anguillarum FKC challenge does not directly induce significant immune gene expression changes in fish skin.
• Increased hemoglobin gene expression in fish skin indicates erythrocyte infiltration, a potential indicator of tissue response or repair, rather than a primary immune response.