The inflammatory chemokine Cxcl18b exerts neutrophil-specific chemotaxis via the promiscuous chemokine receptor Cxcr2 in zebrafish.
Cxcl18b is a chemokine found in zebrafish and in other piscine and amphibian species. Cxcl18b is a reliable inflammatory marker; however, its function is yet to be elucidated. Here, we found that Cxcl18b is chemotactic towards neutrophils, similarly to Cxcl8a/Interleukin-8, the best characterised neutrophil chemoattractant in humans and teleosts. Like Cxcl8a, Cxcl18b-dependent recruitment required the chemokine receptor Cxcr2, while it was unaffected by depletion of the other two neutrophil receptors cxcr1 and cxcr4b. To visualise cxcl18b induction, we generated a Tg(cxcl18b:eGFP) reporter line. The transgene is induced locally upon bacterial infection with the fish pathogen Mycobacterium marinum, but strikingly is not directly expressed by infected cells. Instead, cxcl18b is induced by non-phagocytic uninfected cells that compose the stroma of the granulomas, typical inflammatory lesions formed upon mycobacterial infections. Together, these results suggest that Cxcl18b might be an important contributor to neutrophil chemotaxis in the inflammatory microenvironment and indicate that the zebrafish model could be explored to further investigate in vivo the biological relevance of different Cxcl8-like chemokine lineages.
Institute of Biology, Leiden University, The Netherlands.
Vincenzo
V
Torraca
Institute of Biology, Leiden University, The Netherlands.
Natasja A
NA
Otto
Institute of Biology, Leiden University, The Netherlands.
Aidin
A
Tavakoli-Tameh
Institute of Biology, Leiden University, The Netherlands. Electronic address: a.h.meijer@biology.leidenuniv.nl.
Annemarie H
AH
Meijer
D000818:Animals; D030801:Animals, Genetically Modified; D019743:Chemokines, CXC / Q000235:genetics / Q000378:metabolism*; D002633:Chemotaxis; D055785:Gene Knockdown Techniques; D006099:Granuloma / Q000276:immunology*; D018836:Inflammation Mediators / Q000378:metabolism*; D016209:Interleukin-8 / Q000378:metabolism; D009165:Mycobacterium Infections, Nontuberculous / Q000276:immunology*; D019910:Mycobacterium marinum / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology*; D019718:Receptors, CXCR4 / Q000235:genetics; D023062:Receptors, Interleukin-8A / Q000235:genetics; D023063:Receptors, Interleukin-8B / Q000378:metabolism*; D015027:Zebrafish / Q000276:immunology*; D029961:Zebrafish Proteins / Q000235:genetics
C471276:CXCR4b protein, zebrafish; D019743:Chemokines, CXC; C000625045:Cxcl18b protein, zebrafish; D018836:Inflammation Mediators; D016209:Interleukin-8; D019718:Receptors, CXCR4; D023062:Receptors, Interleukin-8A; D023063:Receptors, Interleukin-8B; D029961:Zebrafish Proteins
Inflammatory chemokine; Innate immunity; Leukocyte biology; Mycobacterium marinum; Neutrophil chemotaxis; Zebrafish