Anti-proliferative effect of non-steroidal glucocorticoid receptor agonist compound a in cells stimulated with SEG

FERNÁNDEZ LYNCH MJ; SARRATEA MB ; MALCHIODI EL; DÍAZ MARIÁNGELES; NOLI TRUANT S; ANTONOGLOU MB; DE MARZI MC; FERNÁNDEZ MM

Mar del Plata

Congreso; LXIV Reunión Anual de la SAI; 2016

SAIC-SAI

Bacterial superantigens, such as SEG, are exotoxins that trigger peptide-non-specific T cell proliferation and proinflammatory cytokine release. Immunosuppressants, like glucocorticoids, are used to revert inflammatory actions in superantigen related diseases. However, we have previously reported resistance to dexamethasone by enterotoxin gene cluster and group II toxins in peripheral blood mononuclear cells. Non-steroidal glucocorticoid receptor agonists (SEGRAs), like Compound A, exert their action by transrepressing activation of proinflammatory pathways [Bossher 2005]. Therefore, we aim to study the pathways involved in glucocorticoid resistance and whether SEGRAs can exert a better immunosuppressive action than dexamethasone.SEG was recombinantly produced in E. coli and purified by Ni-NTA. PBMCs were enriched from heparinized blood using Ficoll-Hypaque gradient, cultured for 48 hours for proliferation assessment with 3H-thymidine under different stimuli (SEG 10ug/ml, dexamethasone 10-5 M, Compound A 10-6 to 10-4M, Rapamycin 1-200 nM and BAY 11-7082 1-50 uM.) The effect of SEG on macrophage cell line RAW and T cell line LBR was also assessed by proliferation assays.PBMCs proliferation induced by 10ug/ml SEG is inhibited by NFKB inhibitor BAY 11-7082 at 10 uM (two way ANOVA p>0.05) showing the importance of this inflammatory transcription factor in the superantigen action mechanism. 10uM Compound A also inhibits SEG induced proliferation showing a better immunosuppressive activity than 10 uM Dexamethasone treated cells which show significant proliferation (p0.05). The study on isolated cell lines shows that SEG is unable to induce proliferation lacking costimulatory signals rendering these pathways as interesting targets.Understanding the underlying mechanisms of glucocorticoid resistance in Staphylococcus toxin related diseases can help improve treatment outcome in patients being SEGRAs promising drugs for treating these diseases.