Autoantibodies from sjogren's syndrome trigger apoptosis in salivary gland cell line

The presence of serum autoantibodies has been associated with Sj¨ogren’s syndrome (SS), an autoimmune rheumatic disease that targets salivary and lachrymal glands. The association of apoptosis with autoantibodies production seems to play a role in the pathogenesis of glandular damage. The best-defined antibodies in SS are those reacting with the ribonucleoprotein antigens SS-A (Ro) and SS-B (La). Anti-Ro antibodies are found in about 70–90%, and anti-La in approximately the same frequency, of patients with primary SS. The objective of this work was to explorewhether anti-Ro and anti-La autoantibodies purified from Sj¨ogren IgG fractions are able to trigger apoptotic process in the human salivary gland cell line A-253. Anti-Ro and anti-La autoantibodies were purified on protein G Sepharose affinity column and used for the A- 253 cell treatment. Apoptosis induced by autoantibodies was revealed by FACS analysis, and the active caspase-3 and the cleaved caspase-3 substrate poly (ADP-ribose) polymerase (PARP) was demonstrated by colorimetric assay andWestern blot. This report shows that anti-Ro and anti-La autoantibodies, but not healthy IgG, activate the caspase-3 and determine the cleavage of PARP in A-253 cells. Apoptosis triggered by Sj¨ogren autoantibodies could be responsible for the impairment of the secretory function in the salivary glands