International Immunology Advance Access published online on October 23, 2009
International Immunology, doi:10.1093/intimm/dxp103
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Induction of TNF-alpha-converting enzyme-ectodomain shedding by pathogenic autoantibodies
1 Section of Cell Biology, Department of Human Anatomy and Histology, University of Bari Medical School, piazza Giulio Cesare 1, I-70124 Bari, Italy
2 Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
3 Department of Internal Medicine and Clinical Oncology
4 Section of Rheumatology, Department of Internal Medicine and Public Medicine, University of Bari Medical School, piazza Giulio Cesare 1, I-70124 Bari, Italy
Correspondence to: M. Sisto; E-mail: m.sisto{at}anatomia.uniba.it
The release of the soluble form of tumor necrosis factor (TNF)-alpha from the plasma membrane occurs through the activation of the secretase tumor necrosis factor-alpha-converting enzyme (TACE). The current study was designed to examine whether the anti-Ro/SSA autoantibodies (Abs) are capable to regulate TACE expression in non-neoplastic human salivary gland epithelial cells (SGEC) cultures. We investigated the effect of anti-Ro/SSA Abs on the localization and abundance of cell-surface TACE and on TACE pro-domain-shedding and activation. In addition, the potential physiological consequences of TNF-alpha blockage by the biological agent Adalimumab on post-translational regulation of TACE are discussed. Anti-Ro/SSA Abs were purified from IgG fractions of patients with primary Sjögren's syndrome, using Sepharose 4B-Ro/SSA affinity columns. Flow cytometry, reverse transcription–PCR, western blot and immunohistochemistry were used to study TACE expression on SGEC and TACE regulation by Abs. Our study demonstrated a dose-dependent increase of TACE messenger RNA (mRNA) expression in anti-Ro/SSA Abs-treated SGEC, followed by internalization, pro-domain shedding and activation of TACE protein, suggesting that increased TACE activity is necessary for the release of TNF-alpha observed in anti-Ro/SSA Abs-stimulated SGEC. Adalimumab treatment brought TACE mRNA and surface TACE expression to levels than those observed in untreated SGEC. These data suggest that the effect of anti-Ro/SSA Abs on TACE expression and intracellular distribution is exerted by TNF-alpha production.
Keywords: adalimumab, autoantibodies, epithelial cells, shedding, TACE
* These authors contributed equally to this study and both are equally considered as ‘first author’.
Received 7 May 2009, accepted 18 September 2009.