Objective.Minor salivary gland specimens were analyzed to investigate dysregulation of the proteasome system in patients with Sjögren’s syndrome (SS) and patients with sicca syndrome.Methods.Labial biopsy specimens from 17 patients with SS and 11 patients with non-autoimmunesicca syndrome were analyzed by immunohistochemistry for expression of the inducible proteasomal subunits ß1i, ß2i, and ß5i. The infiltrating subsets of lymphocytes were characterized using immunofluorescence stainings against the cell-surface markers CD20 and CD27. Two-dimensional electrophoresis and immunoblotting were used for detection of the proteasomal subunits ß1 and ß1i in peripheral blood monocyte cells. Gene expression of the constitutive subunits ß1, ß2, and ß5 and the corresponding inducible subunits ß1i, ß2i, and ß5i was further investigated at the mRNA level in small lip biopsies using real-time polymerase chain reaction.Results.The expression of ß1i in infiltrating and peripheral immune cells was altered in patients with SS compared to patients with non-autoimmune sicca syndrome and healthy controls. No significant differences were found in ß2i and ß5i expression between the same groups in small lip biopsies. Chisholm-Mason grade and ß1i expression were found to be inversely correlated (Spearman r = −0.461, p = 0.014). The phenotype and distribution of the lymphocytic infiltrate showed no differences between patients with primary and secondary SS regardless of ß1i expression.Conclusion.The proteasomal ß1i subunit is dysregulated in peripheral white blood cells and in inflammatory infiltrates of minor salivary glands in patients with SS.
Interferon gamma-inducible protein 16 (IFI16) and anti-IFI16 antibodies in primary Sjögren’s syndrome: findings in serum and minor salivary glands
