Glucocorticoid-Induced Attenuation of the Inflammatory Response in Zebrafish

Abstract

Glucocorticoids are steroid hormones that are secreted upon stress. Their effects are mediated by the glucocorticoid receptor, which acts as a transcription factor. Because the antiinflammatory activity of glucocorticoids has been well established, they are widely used clinically to treat many inflammatory and immune-related diseases. However, the exact specificity, mechanisms, and level of regulation of different inflammatory pathways have not been fully elucidated. In the present study, a tail fin amputation assay was used in 3-day-old zebrafish larvae to study the immunomodulatory effects of the synthetic glucocorticoid beclomethasone. First, a transcriptome analysis was performed, which showed that upon amputation mainly immune-related genes are regulated. This regulation was inhibited by beclomethasone for 86% of regulated genes. For two immune-related genes, tlr4bb and alox5ap, the amputation-induced increase was not attenuated by beclomethasone. Alox5ap is involved in eicosanoid biosynthesis, but the increase in leukotriene B4 concentration upon amputation was abolished, and lipoxin A4 levels were unaffected by beclomethasone. Furthermore, we studied the migration of neutrophils and macrophages toward the wound site. Our results show that amputation induced migration of both types of leukocytes and that this migration was dependent on de novo protein synthesis. Beclomethasone treatment attenuated the migratory behavior of neutrophils in a glucocorticoid receptor-dependent manner but left the migration of macrophages unaffected. In conclusion, beclomethasone has a dramatic inhibitory effect on the amputation-induced proinflammatory gene regulation, and this is reflected in an inhibition of the neutrophil migration but not the migration of macrophages, which are likely to be involved in inflammation resolution.

nr3c1 null mutant zebrafish are viable and reveal DNA-binding-independent activities of the glucocorticoid receptor

“…In agreement with results obtained by Chatzopoulou and coworkers 2 with a tail fin amputation assay, the challenge with DSS induced a pro-inflammatory reaction with enhanced transactivation of the genes encoding the cytokines Il1β, Il8 and Il6 and the metalloproteinase Mmp-13, involved in inflammatory processes, in both WT and gr s357/s357 larvae, but not in the gr −/− strain. Subsequent treatment with DEX significantly depressed the transcription of the above genes, whereas no change was observed in the gr −/− strain.…”

“…Analysis of mmp - 9 , a metalloproteinase gene known to be down-regulated by GCs 2,28,29 , showed a statistically significant reduction of its expression after DEX in gr +/+ and gr s357 / s357 line, but not in gr −/− , in agreement with the loss of non-canonical, GRE-independent activity.…”

“…These hormones regulate many physiological processes, including glucose homeostasis, intermediary metabolism 1 , inflammatory 2 and stress responses. Moreover, in fish, GCs are also involved in water and electrolyte homeostasis 3 and their production is regulated by the hypothalamus-pituitary-interrenal (HPI) axis that is equivalent to the mammalian hypothalamus-pituitary-adrenal (HPA) axis 4,5 .…”

Stress, inflammation, and eicosanoids: an emerging perspective

“…Similar effects are seen in glial cells and with the corticosteroid drug dexamethasone in human blood monocytes [41, 42]. Abrogation of inflammatory response by glucocorticoids is also observed in zebrafish in response to stress caused by tail vein amputation along with decrease in leukotriene B4 (LTB4) synthesis, an effect that is also seen upon treatment with the synthetic glucocorticoid beclomethasone [43]. Proteasome and eicosanoid profiling of human fibroblasts show that inflammation upregulates a number of eicosanoids synthesized by COX and LOX, such as PGE1, PGE2, TXB2, 11-HETE, and 12-HETE.…”

The First Fifteen Years of Steroid Receptor Research in Zebrafish; Characterization and Functional Analysis of the Receptors

“…Administration of the antidepressant fluoxetine as well as social interactions were shown to restore normal behavior [75,77]. Using this mutant, it was demonstrated that Gr mediates the glucocorticoid-induced inhibition of leukocyte migration upon wounding [78] and the stimulation of the formation of hematopoietic stem and progenitor cells (HSPCs) by glucocorticoids [79]. In addition, it was found that light adaptation in the retina was disturbed in mutant larvae [80].…”