Peritoneal cavity phagocytes from the teleost sea bass express a glucocorticoid receptor (cloned and sequenced) involved in genomic modulation of the in vitro chemiluminescence response to zymosan

AbstractTo gain further insight into the role of cortisol in Wsh innate immune responses, we cloned and sequenced a 2592 bp cDNA from sea bass(Dicentrarchus labrax) peritoneal leukocytes (PCLs) encoding a glucocorticoid receptor (DlGR1). The deduced aminoacid sequence displayedthat DlGR1 belong to a multigenic family of steroid hormone receptors, and exhibited high homology (80%) to the Burton’s mouth breeder(Haplochromis burtoni) HbGR1. The DlGR1 functional domains presented homologies with those of several vertebrate species. In situ hybridizationassay revealed that DlGR1 was expressed in macrophages and neutrophils from the peritoneal cavity. Since in a previous paper, sea bassPCL chemiluminescence response (CL) has been related to increased respiratory burst of phagocytes stimulated with zymosan, PCLs, preincubatedin vitro with cortisol at various concentrations, were assayed for their CL response. Dose-dependent cortisol inhibitory eVects, andsigniWcant competitive activity of a low concentration of mifepristone (RU486), a glucocorticoid-receptor blocker, supported that cortisol–GRinteraction was involved in modulating CL response via a genomic pathway. Results also indicated that cortisol could be eVective through anadditional not-genomic way, and showed that high doses of RU486 exerted an inhibitory eVect on PCL chemiluminescence activity.© 2006 Elsevier Inc. All rights reserved.