BACKGROUND: Studies on innate immunity have benefited from the introduction of zebrafish as a model system. Transgenic fish expressing fluorescent proteins in leukocyte populations allow direct, quantitative visualization of an inflammatory response in vivo. It has been proposed that this animal model can be used for high-throughput screens aimed at the identification of novel immuno-modulatory lead compounds. However, current assays require invasive manipulation of fish individually, thus preventing high content screening.
RESULTS: Here, we show that specific, non-invasive damage to lateral line neuromast cells can induce a robust acute inflammatory response. Exposure of fish larvae to sub-lethal concentrations of copper sulfate selectively damages the sensory hair cell population inducing infiltration of leukocytes to neuromasts within 20 minutes. Inflammation can be assayed in real-time using transgenic fish expressing fluorescent proteins in leukocytes or by histochemical assays in fixed larvae. We demonstrate the usefulness of this method for chemical and genetic screens to detect the effect of immuno-modulatory compounds and mutations affecting the leukocyte response. Moreover, we transformed the assay into a high-throughput screening method by using a customized automated imaging and processing system that quantifies the magnitude of the inflammatory reaction.
CONCLUSIONS: This approach allows rapid screening of thousands of compounds or mutagenized zebrafish for effects on inflammation and enables the identification of novel players in the regulation of innate immunity and potential lead compounds towards new immuno-modulatory therapies. We have called this method the Chemically-Induced Inflammation Assay, or ChIn Assay. See Commentary article: http://www.biomedcentral.com/1741-7007/8/148.