Fish Erythrocyte Extracellular Traps (FEETs) are an evolutionarily conserved cellular process triggered by different...

Area of Science:

• Immunology
• Cell Biology
• Comparative Physiology

Background:

• Unlike mammalian erythrocytes, fish erythrocytes are nucleated and possess immune functions beyond oxygen transport.
• ETosis is a conserved innate immune mechanism involving extracellular DNA traps to capture and kill pathogens.
• Fish erythrocytes are investigated as potential mediators of ETotic responses due to their nucleated nature and immune capabilities.

Purpose of the Study:

• To investigate whether fish erythrocytes can exhibit ETotic-like responses.
• To characterize the formation and inducers of these ETotic-like responses in fish erythrocytes.
• To identify the cellular mechanisms underlying fish erythrocyte ETosis.

Main Methods:

• Exposure of zebrafish (Danio rerio) and Atlantic salmon (Salmo salar) erythrocytes to chemical and physiological inducers of ETosis.
• Microscopic analysis to observe the formation of extracellular traps.
• Biochemical assays to assess the involvement of protein kinase C (PKC) and mitochondrial reactive oxygen species (mROS).

Main Results:

• Fish erythrocytes from both zebrafish and Atlantic salmon demonstrated ETotic-like responses when stimulated.
• These structures were termed Fish Erythrocyte Extracellular Traps (FEETs).
• FEET formation was induced by mammalian ETosis inducers like PMA and ionomycin, and dependent on PKC activation and mROS generation.

Conclusions:

• This study provides the first evidence that fish erythrocytes can perform ETotic-like responses.
• FEETs represent a novel innate immune mechanism in fish erythrocytes.
• This finding expands our understanding of the immune repertoire of fish erythrocytes and innate immunity in vertebrates.