Impaired expression of Act1mRNA in B cells of patients with Sjögren's syndrome

Abstract

Sjögren's syndrome (SS) is a systemic autoimmune disorder characterized by profound lymphocytic infiltration into the lacrimal and salivary glands, thereby diminished secretory function. B cell hyper-activation is a predominant feature of SS related to hypergammaglobulinemia and production of autoantibodies. The adaptor molecule NF-kB activator 1 (Act1) plays an important role in the homeostasis of B cells by attenuating CD40 and B cell-activating factor belonging to the tumor necrosis factor family receptor (BAFFR) signaling. Act1-deficient mice develop autoimmune manifestations similar to SS, which are hypergammaglobulinemia, high levels of anti-SSA and anti-SSB autoantibodies. In this study, to investigate the role of Act1 in the pathogenesis of SS, we examined Act1mRNA expressions in B cells from patients with SS and discussed the association of Act1 with parameters and clinical manifestations of SS. We showed the low level of Act1mRNA expression in patients with SS and reciprocal association of Act1 with serum IgG level. Diminished Act1mRNA expression in SS may be associated with B cell hyperactivity and elevated immunoglobulin production in SS by uncontrolled B cell activation signal through CD40 and BAFFR. © 2012, The Japan Society for Clinical Immunology. All rights reserved.