Il-1β and Reactive Oxygen Species Differentially Regulate Neutrophil Directional Migration and Basal Random Motility in a Zebrafish Injury–Induced Inflammation Model

Abstract

During inflammation, the proper inflammatory infiltration of neutrophils is crucial for the host to fight against infections and remove damaged cells and detrimental substances. IL-1β and NADPH oxidase–mediated reactive oxygen species (ROS) have been implicated to play important roles in this process. However, the cellular and molecular basis underlying the actions of IL-1β and ROS and their relationship during inflammatory response remains undefined. In this study, we use the zebrafish model to investigate these issues. We find that, similar to that of NADPH oxidase–mediated ROS signaling, the Il-1β–Myd88 pathway is required for the recruitment of neutrophils, but not macrophages, to the injury-induced inflammatory site, whereas it is dispensable for bacterial-induced inflammation. Interestingly, the Il-1β–Myd88 pathway is independent of NADPH oxidase–mediated ROS signaling and critical for the directional migration, but not the basal random movement, of neutrophils. In contrast, the NADPH oxidase–mediated ROS signaling is required for both basal random movement and directional migration of neutrophils. We further document that ectopic expression of Il-1β in zebrafish induces an inflammatory disorder, which can be suppressed by anti-inflammatory treatment. Our findings reveal that the Il-1β–Myd88 axis and NADPH oxidase–mediated ROS signaling are two independent pathways that differentially regulate neutrophil migration during sterile inflammation. In addition, Il-1β overexpressing Tg(hsp70:mil-1β_eGFP;lyz:DsRed2)hkz10t;nz50 transgenic zebrafish provides a useful animal model for the study of chronic inflammatory disorder and for anti-inflammatory drug discovery.

Comparison of Two Chemically-Induced Colitis-Models in Adult Zebrafish, Using Optical Projection Tomography and Novel Transcriptional Markers

“…The role of IL-6 has not been scrutinized in colitis models using zebrafish until now. In other fish-based inflammation studies, IL-6 has been involved in both amplification and dampening of the immune reaction in trout head kidney macrophages [37] and was up-regulated in zebrafish skin as a response to IL-1β expression in a recent inflammation model [38]. Interestingly, the IL-6 gene showed no alterations of expression level compared to controls in this study.…”

Mechanisms of epithelial wound detection

“…Interleukin 1 (IL-1) is one of the first transcriptionally induced cytokines after tissue damage, and crucial for cell lysis detection. Neutrophil recruitment to injected necrotic cells, liver burn damage in mice, or tail fin wounds in zebrafish larvae is severely inhibited in animals deficient in IL-1 signaling [13–15]. DAMPs enhance IL-1 transcription through binding to pattern recognition receptors and by promoting proteolytic maturation of IL-1 precursor peptide through inflammasome-mediated activation of caspase-1 [16,17].…”

Vibsanin B Preferentially Targets HSP90β, Inhibits Interstitial Leukocyte Migration, and Ameliorates Experimental Autoimmune Encephalomyelitis

“…Recently, the zebrafish model has been used to analyze the dynamic course of leukocyte chemotactic migration in vivo, which facilitates novel insights into certain inflammatory diseases that involve leukocytes. Thus, zebrafish is an ideal model organism to study the biological behavior of leukocytes through live imaging techniques (8)(9)(10)(11). We previously constructed a transgenic zebrafish line TG:zlyz-enhanced GFP (EGFP) for tracking leukocyte migration in response to acute injury in vivo (9).…”