Adherent Intestinal Cells From Atlantic Salmon Show Phagocytic Ability and Express Macrophage-Specific Genes.

Youngjin Park,Jorge M.O Fernandes,Qirui Zhang,Viswanath Kiron,Geert F Wiegertjes

doi:10.3389/fcell.2020.580848

Youngjin Park, Jorge M.O Fernandes + Show 3 more

Open Access

https://doi.org/10.3389/fcell.2020.580848

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Abstract

Our knowledge of the intestinal immune system of fish is rather limited compared to mammals. Very little is known about the immune cells including the phagocytic cells in fish intestine. Hence, employing imaging flow cytometry and RNA sequencing, we studied adherent cells isolated from healthy Atlantic salmon. Phagocytic activity and selected gene expression of adherent cells from the distal intestine (adherent intestinal cells, or AIC) were compared with those from head kidney (adherent kidney cells, or AKC). Phagocytic activity of the two cell types was assessed based on the uptake of Escherichia coli BioParticlesTM. AIC showed phagocytic ability but the phagocytes were of different morphology compared to AKC. Transcriptomic analysis revealed that AIC expressed genes associated with macrophages, T cells, and endothelial cells. Heatmap analysis of selected genes indicated that the adherent cells from the two organs had apparently higher expression of macrophage-related genes. We believe that the adherent intestinal cells have phagocytic characteristics and high expression of genes commonly associated with macrophages. We envisage the possibilities for future studies on enriched populations of adherent intestinal cells.

Highlights

Teleost fishes have both organized and diffuse lymphoid tissues
Employing the normalized read counts from DESeq2 analyses, we describe the expression of 34 cell-specific genes and 42 immune-related genes in AIC compared to AKC
The gut-associated lymphoid tissues (GALTs) cells are imperative in responding to antigens, both benign and pathogenic

Summary

Introduction

Teleost fishes have both organized and diffuse lymphoid tissues. These tissues differ from those of mammals morphologically and functionally. Fish lack bone marrow and lymph nodes found in mammals. They rely on thymus, (head) kidney and spleen as their key lymphoid organs. The head kidney recruits specific cell types during disease conditions like inflammation (Parra et al, 2015). The head kidney is a well-known primary B cell organ in fishes (Li et al, 2006; Parra et al, 2015)

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