Abstract

Prolonged inflammation can be detrimental because it may cause host toxicity and tissue damage. Indeed, excessive production of inflammatory cytokines is often associated with many autoimmune diseases. In this study we demonstrate that the anti-Ro/SSA autoantibodies (Abs) stimulate the production of pro-inflammatory cytokines IL-6 and IL-8 by human healthy salivary gland epithelial cells (healthy SGEC). The secretion of these cytokines is due to amphiregulin (AREG) that is overexpressed in healthy SGEC treated with anti-Ro/SSA Abs and in Sjögren's syndrome. We have discovered that the up-regulation of AREG occurs through TNF-alpha produced following anti-Ro/SSA Abs treatment. The gene silencing technique was used to study the AREG-TNF-alpha-IL-6/IL-8 secretion pathway, demonstrating that: (i) TNF-alpha gene silencing provokes a significant decrease of proinflammatory cytokines production and AREG expression in anti-Ro/SSA Abs-treated healthy SGEC; (ii) AREG gene silencing has a potent inhibitory effect on TNF-alpha-induced IL-6 and IL-8 secretion in healthy SGEC treated with anti-Ro/SSA Abs. These findings indicate that TACE-mediated AREG shedding plays a critical role in TNF-alpha-induced IL-6 and IL-8 secretion by the human healthy salivary gland epithelial cells, suggesting that this may be one of the possible intracellular mechanisms involved in the salivary glands inflammatory response in Sjögren's syndrome.

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