Single-cell transcriptome analysis reveals a cellular immune response in freshwater dark sleeper (

Area of Science:

• Immunology
• Genomics
• Aquatic Animal Health

Background:

• Aeromonas veronii is a significant co-pathogen affecting both human and aquatic animal health.
• Understanding host-pathogen interactions is crucial for managing infections in aquaculture and wildlife.
• The dark sleeper (Odontobutis potamophila) serves as a model organism for studying teleost immune responses.

Purpose of the Study:

• To investigate the impact of Aeromonas veronii infection on head kidney cells in Odontobutis potamophila using single-cell transcriptome analysis (scRNA-seq).
• To identify specific cellular and molecular changes in immune cells during A. veronii infection.
• To elucidate the gene expression patterns associated with the host's immune defense mechanisms.

Main Methods:

• Single-cell transcriptome analysis (scRNA-seq) was employed to profile gene expression in individual head kidney cells.
• Differential enrichment analysis was performed on B cells and granulocytes to identify significant gene expression changes.
• Specific genes related to immune response, ribosome biogenesis, and antigen presentation were quantified.

Main Results:

• A. veronii infection led to a significant increase in neutrophils and a decrease in eosinophils within granulocytes.
• Neutrophil activation was associated with enhanced ribosome biogenesis (upregulation of RPS12 and RPL12) to combat pathogens.
• Pro-inflammatory mediators (IL1B) and major histocompatibility complex (MHC) class II genes (MHC2A, MHC2DAB) were upregulated, indicating antigen presentation and B cell activation.

Conclusions:

• Aeromonas veronii infection elicits a potent cellular immune response in Odontobutis potamophila head kidney cells.
• The study highlights the role of neutrophils and B cells in the host's defense against bacterial pathogens.
• These findings contribute valuable scRNA-seq data for teleosts, advancing the understanding of immune evolution and head kidney cell differentiation.