Inhibition of Interleukin-1 Signal by Annexin-1 in Phorbol Myristate Acetate Stimulated Lymphocytes

Rhee, Hae Jin; Park, Kun Koo; Na, Doe Sun; Kim, Ha Won

Abstract

Annexin-1 (ANX1) is a 37 kDa protein that is induced and secreted by glucocorticosteroid hormone. The secreted ANX1 has been believed to exert its function by binding to its putative rnembrane receptor. In this report we demonstrate that ANXl receptor (ANX1R) signal blocks the interleukin-1B (IL-1B) receptor signal pathway in human peripheral blood mononuclear cells (PBMCs). When PBMCs were treated with both IL-1B (100 ng/ml) and PMA (10 ng/ml) in the absence or presence of dexamethasone for 5 days, dexamethasone (100 nM) suppressed lymphocyte proliferation to 24% of the control. However addition of anti-ANX1 polyclonal antibody of 1:200 and 1:1,000 dilution to this system induced recovery of proliferation to 80% and 40%, respectively, when compared to the control. In the mixed lymphocyte reaction, dexamethasone suppressed lymphocyte proliferation to 9% of that of control when stimulated with IL-1B (100 ng/ml) and phorbol myristate acetate (10 ng/ml). Addition of anti-ANX1 polyclonal antibody (1:1,000) to this system also recovered the proliferation to 20% of that of the control system. In the ANX1 receptor induction experiment using flow cytometry, ANX1 receptor expression on lymphocytes, CD4+ T cells, CD8+ T cells and monocytes increased depending on the externally added IL-1B ranging from 10 to 1,000 ng/ml. From these results, it is evident that dexamethasone induces ANX1 secretion into the culture medium and anti-ANX1 polyclonal antibody abolishes the effects of dexamethasone. Furthermore these results imply that extracellular ANX1 exerts its effects by binding to the receptor on the cell membrane and the activated signal(s) of ANX1R block IL-1B receptor signal in the lymphocytes.