A chemical enterocolitis model in zebrafish larvae that is dependent on microbiota and responsive to pharmacological agents

Abstract

Inflammatory bowel disease (IBD) results from dysfunctional interactions between the intestinal immune system and microbiota, influenced by host genetic susceptibility. Because a key feature of the pathology is intestinal epithelial damage, potential disease factors have been traditionally analyzed within the background of chemical colitis models in mice. The zebrafish has greatly complemented the mouse for modeling aspects of disease processes, with an advantage for high content drug screens. Larval zebrafish exposed to the haptenizing agent trinitrobenzene sulfonic acid (TNBS) displayed impaired intestinal homeostasis and inflammation reminiscent of human IBD. There was a marked induction of pro-inflammatory cytokines, the degradative enzyme mmp9 and leukocytosis. Enterocolitis was dependent on microbiota and Toll-like receptor signaling, that can be ameliorated by antibiotic and anti-inflammatory drug treatments. This system will be useful to rapidly interrogate in vivo the biological significance of the IBD candidate genes so far identified and to carry out pharmacological modifier screens. Developmental Dynamics 240:288-298,

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

“…In relation to colitis, MMP-9 isconsidered to be the most important protease and it is distinctly overexpressed in both forms of IBD in humans and rodent models [43] [44] [45]. Recently, Oehlers et al [9] reported a significant increase of MMP-9 in larval zebrafish exposed to TNBS and, using adult fish; similar results have been obtained in this study. The acute-phase proteins C3, CRP and SAA were investigated for the first time in a zebrafish-colitis model in the present study, and significant up-regulations of the genes were detected in the intestine of both treated groups after 72 hpi.…”

“…Considering the multifaceted and central role of IL-6 in a number of inflammatory conditions, including IBD [39], the results are not readily explained, but knowledge of IL-6 function and signaling is considered to be inadequate in fish at present [40]. Confirming earlier zebrafish-inflammatory studies [8] [9] [10] [41], the neutrophil-activating chemokineCxCL8 (IL-8) was significantly up-regulated in the TNBS groups after 72 hpi. In the oxazolone-exposed group, CxCL8 transcript levels were also elevated after 72 hpi, albeit at noticeably higher level than in the TNBS group.…”

“…Depletion of these mucus-containing cells and has been reported in intestines of patients with ulcerative colitis and in oxazolone-exposed rodent models; in contrast, Crohn's disease patients and the associated animal models usually exhibit a differentiation of the goblet cell population [13] [21] [32]. A distinct emptying of goblet cells in intestines of oxazolone-exposed adult zebrafish has been reported [6] whereas both an increase in goblet cell density [7] [11] and an unaffected goblet cell population [9] [10] have been observed in models using TNBS and larval/adult zebrafish. Goblet cells in fish have been shown to release mucins as a response to environmental factors, such as formalin [34] and ectoparasites [35], but the effect on skin goblet cells in the present study may be mediated by systemic factors such as cytokines produced in intestinal cells.…”

Inflammatory diseases modelling in zebrafish

“…Broad-spectrum antibiotics increased the low survival rate obtained with high concentrations of TNBS, and even recover the low survival rate of TNBS-exposed myd88 morphants to control levels [60] . In addition, TNBS exposition in larva induced a lesser diversity of bacteria, with an increase in the phylum Proteobacteria (Hydrocarboniphaga daqingensis, Limnobacter sp., Citrobacter freundii, Comamonas sp., Salmonella sp.)…”

“…The same bacteria phyla have been previously observed altered in human IBD [69,70] . Finally, treatment with 5-aminosalicylic acid co-administered with TNBS, prevented the disease alterations induced by the hapten, decreased the expression of il1β, tnfα, ccl20 and il8, and inhibited the increase of myeloid cells in (lys:EGFP) transgenic larva, as well as reduced the recruitment of leucocytes to the intestine and skin in Tg(mpx:EGFP) larvae [59,60] . Similar results were obtained with prednisolone which was also effective against the generation of disease changes, including reduced expression of il1β, tnfα and il8 [60] , a decrease in TNFα and reduction of the number of goblet cells to normal levels [59] .…”