The Immunomodulatory Action of Dexamethasone on Monoclonal Antibody-Producing Hybridoma Cells

Abstract

As found in different studies, glucocorticoid hormones (GCs) as well as interleukin-6 (IL-6) are involved in the modulation of protein glycosylation. In this work we have investigated the immunomodulatory effect of dexamethasone by assessing in vitro IgG glycosylation by monoclonal antibody-producing hybridoma cells. As described in myeloma cell lines, cellular viability and proliferation rates of hybridoma 112D5 cells decrease when cultured with dexamethasone during 24 hours, in a dose-dependent way. Moreover, the corticosteroid triggered apoptosis of the hybridoma, which was observed as soon as 4 h after culturing cells in the presence of the drug. In line with these results, after 24 h, dexamethasone induced a drop in the anti-DNP level of antibodies synthesized by hybridoma 112D5. In previous works we described that asymmetric glycosylation of in vitro synthesized IgG correlated with induction of cell damage. Nevertheless, an increase in asymmetric IgG glycosylation was not observed here, but there was a decrease in the proportion of asymmetrically glycosylated IgG synthesized by the hybridoma after a 4-h culture with the drug. Finally, as results from assessing IL-6 production by ELISA, we conclude that the above described effects of dexamethasone on hybridoma 112D5 cells could not be due to the inhibition of IL-6 synthesis exerted by the corticoid but rather to a direct effect of the drug. Monoclonal antibody (MAb) producing hybridomas provide an excellent in vitro model for the study of the molecular mechanisms involved in immunoglobulin glycosylation.

In Vitro Modulation of Protective Antibody Responses by Estrogen, Progesterone and Interleukin‐6

“…The presence of SH receptors on myeloma and hybridoma cells has been reported elsewhere 41 . In addition, the effects of the steroid dexamethasone on hybridoma 112D5 cells, affecting proliferation as well as antibody synthesis have been reported suggesting that SH receptor expression on 112D5 should not be surprising 42 . As already described on other cell lines E 2 was able to induce ER as well as PR on 112D5 cells 43 .…”

Effect of hydrocortisone on the production and glycosylation of an Fc‐fusion protein in CHO cell cultures

“…Glucocorticoids are known to exert diverse effects on cell growth and survival, depending on the cell type and culture conditions. While glucocorticoids are known to exert an antiproliferative action on several cell lines,18, 19, 31–35 they were also reported to increase DNA synthesis under certain conditions 36. In addition, glucocorticoids were shown to have contradictory effects on cell survival, reducing cell viability by apoptosis in certain cell cultures, while increasing cell survival by decreasing apoptosis in other cultures 20, 37–39.…”

“…Among hormones, glucocorticoids have been widely reported to regulate the production of glycoproteins presumably through their action on glycosyltransferases and glycosidases, and in some cases also their secretion 17. In addition to their effect on protein glycosylation, glucocorticoids are also involved in the regulation of many other biological functions including cell growth, proliferation, differentiation, apoptosis, metabolism, and they can act as immunomodulators suppressing or promoting the synthesis and release of various cytokines 18–22. The mechanism of action of glucocorticoids is complex and most of the time involves the activation of cytoplasmic glucocorticoid receptors (GRs) 23.…”

The pivotal nature of sugars in normal physiology and disease

“…-IL-6 which affects IgG glycosylation in vitro [64,65] and in vivo where it is associated with increased serum agalactosyl IgG (IgG-G0) levels in pristane-induced arthritic mice [66]. -TNF-α, a pro-inflammatory cytokine which affects glycoprotein biosynthesis in synoviocytes [67].…”

“…-Glucocorticoids such as dexamethasone affect IgG glycosylation [62,65]. -Increased oestrogen levels induce glycosylation changes of acute phase proteins such as α1-acid glycoprotein (α1-AGP), α1-protease inhibitor and α1-antichymotrypsin [72].…”