Sjögren's Syndrome Autoantibodies Provoke Changes in Gene Expression Profiles of Inflammatory Cytokines Triggering a Pathway Involving TACE/NF-κB

We explore the association of the inflammatory gene expression profile observed in the chronic inflammatory autoimmune disorder Sjögren's syndrome (SS) with changes in TNF-α converting enzyme (TACE), tumor necrosis factor (TNF)-α and nuclear factor (NF)-κB levels showing that pathways that include TNF-α signaling converge on NF-κB contributing to exacerbate the diseases. The treatment of human salivary gland epithelial cells (SGECs) with SS anti-Ro/SSA autoantibodies (Abs) result in a progressive increase in NF-κB-DNA binding, that includes a marked enhancement in NF-κB subunit p65 protein-DNA binding. A human cytokine multi-analyte array demonstrated that the NF-κB proinflammatory target genes, increased by anti-Ro/SSA Abs treatment, includes CXC chemokines (CXCL1, CXCL6 and CXCL9), CC chemokines (CCL2, CCL13 and CCL20), interleukins (IL-1α, IL-1β, IL-1F8, IL-6, IL-8, IL-9, IL-13, IL-17 and IL-22) and their receptors (IL-1RN, IL-10Rα, IL-13Rα, CCR1, CCR2, CCR3, CCR4 and CXCR1). Blockade of TACE through the use of the specific inhibitor TAPI-1 regulates proinflammatory cytokines production in SGEC treated with anti-Ro/SSA Abs inhibiting NF-κB nuclear translocation and activation. To further investigate the role of NF-κB on anti-Ro/SSA Abs-determined proinflammatory gene expression, we used the inhibitory protein IκB-α dominant negative super-repressor as inhibitor of NF-κB-DNA binding, demonstrating that transfection with dominant-negative IκB-α in anti-Ro/SSA-treated SGEC determined a marked reduction of proinflammatory cytokines gene expression. Although further studies are needed to clarify the mechanisms underlying SS, our results demonstrate that SS Abs exert their pathogenic effects via triggering the TACE/TNF-α/NF-κB axis.