Mobilisation and dysfunction of haematopoietic stem/progenitor cells after Listonella anguillarum infection in ayu, Plecoglossus altivelis

Abstract

Haematopoietic stem/progenitor cells (HSPCs) can mobilise into blood and produce immune cell lineages following stress. However, the homeostasis and function of HSPCs after infection in teleosts are less well known. Here, we report that Listonella anguillarum infection enhances HSPC mobilisation and reduces their differentiation into myeloid cells in ayu (Plecoglossus altivelis), an aquacultured teleost in East Asia. We established a colony-forming unit culture (CFU-C) assay to measure HSPCs using conditioned medium from peripheral blood mononuclear cells stimulated with phytohaemagglutinin. The number of CFU-Cs decreased in the head kidney and increased in the blood and spleen of ayu infected with L. anguillarum. HSPC mobilisation after L. anguillarum infection was mediated by norepinephrine. Furthermore, HSPCs from ayu treated with L. anguillarum lipopolysaccharide (LPS) showed defective myeloid differentiation and could no longer rescue L. anguillarum-infected ayu. HSPC expansion was suppressed after L. anguillarum infection or its LPS treatment in vitro. These results reveal a link between HSPC regulation and pathogen infection in teleosts.

A Novel Lipopolysaccharide Recognition Mechanism Mediated by Internalization in Teleost Macrophages

“…Ayu ( Plecoglossus altivelis ), weighing 40 ± 5 g each, were used in all experiments. This strain has undergone seven successive generations of mass selection ( 31 ). The fish were kept at 20–22°C in a recirculating system using filtered water.…”

“…Blocking of unbound binding sites was performed using 5% teleost gelatin (Sigma Aldrich). The anti-IL-1β and anti-TNF antibodies come from our previous studies ( 31 , 34 ). One hundred microliters of 5 μg/ml anti-IL-1β or anti-TNF antibody was added to each well, incubated for 1 h, and washed three times.…”

CXCR3.1 and CXCR3.2 Differentially Contribute to Macrophage Polarization in Teleost Fish

“…1, weighing 40 6 5 g each) were used in all experiments. This strain has undergone seven successive generations of mass selection, with no graft-versus-host effects (23). The fish were kept in freshwater tanks at 20-22˚C in a recirculating system using filtered water.…”

“…For Western blot analysis, the proteins were resolved using SDS-PAGE, transferred to membrane, incubated with specific Abs, and visualized using an ECL Western blotting detection system. Ayu TNF (P. altivelis TNF [PaTNF]) Abs were prepared using a recombinant PaTNF protein in our laboratory (23). Ayu IL-10 (P. altivelis IL-10 [PaIL-10]) Abs…”

The synergistic interaction of thermal stress coupled with overstocking strongly modulates the transcriptomic activity and immune capacity of rainbow trout (Oncorhynchus mykiss)

“…The spleen was selected for transcriptomic analysis as it is a major secondary lymphoid organ that represents the "meeting point" for pathogens and immune cells and is thus characterised by a generally remarkable magnitude of responses [43][44][45] . The head kidney plays a central role in the haematopoiesis of fish, also as a major reservoir of myeloid cells, which act as first responders upon pathogenic invasion [46][47][48] . The head kidney's ability to eliminate pathogens and orchestrate inflammatory responses has previously been studied under various conditions (diets and exposure to stressors and pathogens) as a reference for the immunocompetence and was investigated here in vitro after stimulation with the model pathogen Aeromonas salmonicida.…”