Localization of Th subsets in salivary gland of Sjögren's syndrome

Objectives:Sjögren's syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration into the salivary and lacrimal glands with concomitant destruction of the glandular tissue. We had reported that T helper (Th) 1 / Th2 balance was associated with the initiation and progression of SS. Recently, Th17 and regulatory T cells (Treg) had been shown to have critical function in a variety of autoimmune disease. Moreover, the localization of Th subsets such as Th1, Th2, Th17, and Treg at each part of lesion has not been still poorly understood. Therefore, the aim of this study was to investigate the localization of these Th subsets in the labial salivary glands (LSGs) from SS patients. Methods:Thirty-two patients with SS and 16 healthy controls were included in this study. Th subsets of infiltrating lymphocytes in the LSGs were examined by immunohistochemical staining. The mRNA expression of these Th type molecules including cytokines, chemokines, and transcription factors was determined by real-time polymerase chain reaction. In addition, lymphocytes without germinal center (GC) : (GC (-)) and lymphocytes with GC : (GC (+)) were extracted by using laser capture microdissection, and then, mRNA expression of these molecules in each part of lesion compared between two groups. Results:In SS patients, the expression of Th17 type molecules was increased more than that in healthy controls. Whereas the expression of Th17 and Treg type molecules had no association with the degree of lymphocytic infiltration. In addition, Th1 and Th17 type molecules were detected strongly in the GC (-), while Th2 type molecules were in the GC (+). Conclusions:These results suggest that SS has definitive localization of Th subsets in the lesions of LSGs. Furthermore, SS might be initiated by Th1 and Th17 cells and progress in association with Th2 cells.