Salivary gland expression of transforming growth factor beta isoforms in Sjogren's syndrome and benign lymphoepithelial lesions

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Abstract
Aim: Transforming growth factor β (TGF-β) is involved in the control of autoimmune reactions, cell proliferation, and the accumulation of lymphocytes within organs. The aim of this study was to determine the expression of TGF-β in salivary glands from patients with primary Sjogren’s syndrome (SS) and benign lymphoepithelial lesions (BLEL) with emphasis on ductal epithelium. Methods: Immunoperoxidase staining for TGF-β isoforms and Ki67 antigen was performed on formalin fixed sections of labial glands from patients with primary SS (n = 15) and controls (n = 5) and parotid glands reported as BLEL (n = 5) or normal (n = 5). Ductal expression of TGF-β was quantified by absorbance measurements using image analysis. The specificity of staining was confirmed by peptide blocking studies. Results: All TGF-β isoforms were detected within the cytoplasm of most lymphocytes, endothelial cells, and ducts in all specimens. Acinar expression was variable and weaker than that seen in ducts. Absorbance measurements revealed that the expression of all isoforms was greater in ducts within primary SS glands than in control glands. Ductal expression in control parotid glands was greater than that seen in BLEL glands, irrespective of the presence of adjacent lymphoid infiltrates. Comparisons between control specimens showed that ductal expression of all isoforms was highest in parotid glands, whereas no differences were detected between primary SS and BLEL glands. Ki67 positive lymphocytes and duct cells were mainly restricted to pathological specimens, with BLEL glands containing larger populations of positive cells than primary SS glands. Conclusion: These results demonstrate complex and variable changes in ductal expression of TGF-β in primary SS and BLEL, which may be important in the control of lymphoid infiltration and the proliferation of lymphocytes and ductal epithelium.