17β-Estradiol affects the innate immune response in common carp

Area of Science:

• Immunology
• Endocrinology
• Aquatic Animal Health

Background:

• Inflammation is a critical immune response to injury, requiring tight regulation by various mediators.
• Estrogens, like 17β-estradiol (E2), are known to influence immune functions.
• Understanding E2's role in fish immunity is crucial for aquaculture and disease management.

Purpose of the Study:

• To investigate the immunoregulatory properties of 17β-estradiol (E2) in common carp.
• To determine the in vitro effects of E2 on macrophage activity and polarization.
• To assess the in vivo effects of E2 during Aeromonas salmonicida-induced inflammation.

Main Methods:

• In vitro assays examined E2's impact on lipopolysaccharide (LPS)-stimulated macrophages.
• In vivo studies involved feeding E2-treated food to Aeromonas salmonicida-infected carp.
• Gene expression analysis of inflammatory mediators, estrogen receptors, and aromatase was performed on head kidney samples.

Main Results:

• In vitro, E2 reduced LPS-stimulated pro- and anti-inflammatory gene expression in carp macrophages.
• In vivo, E2-treated feeding upregulated both pro-inflammatory (il-12p35, cxcb2) and anti-inflammatory (arginase 1, arginase 2, il-10, mmp9) mediators in infected fish.
• In vivo, E2 also increased the expression of estrogen receptors and aromatase CYP19 in infected carp.

Conclusions:

• Estrogens, specifically 17β-estradiol, modulate the innate immune response in common carp.
• The in vitro and in vivo effects of E2 on carp immunity are contrasting, indicating complex regulatory mechanisms.
• E2 likely exerts indirect immunomodulatory actions in vivo, involving cellular targets beyond macrophages.