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Annexin-1 is an anti-inflammatory protein that plays an important homeostatic role in innate immunity; however, its potential actions in the modulation of adaptive immunity have never been explored. Although inactive by itself, addition of annexin-1 to stimulated T cells augmented anti-CD3/CD28-mediated CD25 and CD69 expression and cell proliferation. This effect was paralleled by increased nuclear factor-kappaB (NF-kappaB), nuclear factor of activated T cells (NFATs), and activator protein-1 (AP-1) activation and preceded by a rapid T-cell receptor (TCR)-induced externalization of the annexin-1 receptor. Interestingly, differentiation of naive T cells in the presence of annexin-1 increased skewing in Th1 cells; in the collagen-induced arthritis model, treatment of mice with annexin-1 during the immunization phase exacerbated signs and symptoms at disease onset. Consistent with these findings, blood CD4+ cells from patients with rheumatoid arthritis showed a marked up-regulation of annexin-1 expression. Together these results demonstrate that annexin-1 is a molecular "tuner" of TCR signaling and suggest this protein might represent a new target for the development of drugs directed to pathologies where an unbalanced Th1/Th2 response or an aberrant activation of T cells is the major etiologic factor.

Original publication

DOI

10.1182/blood-2006-05-022798

Type

Journal article

Journal

Blood

Publication Date

01/02/2007

Volume

109

Pages

1095 - 1102

Keywords

Animals, Annexin A1, Antigens, CD, Antigens, Differentiation, T-Lymphocyte, Arthritis, Cell Differentiation, Cell Proliferation, Cells, Cultured, Humans, Immunity, Interleukin-2 Receptor alpha Subunit, Lectins, C-Type, Lymphocyte Activation, Mice, Receptors, Antigen, T-Cell, T-Lymphocytes, Th1 Cells