Cytokine mRNA expression in the labial salivary gland tissues from patients with primary Sjögren's syndrome

Abstract

The pattern of cytokine mRNA expression in frozen minor salivary gland tissues from patients with primary Sjögren's syndrome (pSS) (n = 12) and controls (n = 8) using an in situ hybridization technique and oligonucleotide probes of interleukin-1 beta (IL-1 beta), tumour necrosis factor alpha and beta (TNF-alpha and TNF-beta), interleukin-6 (IL-6), interleukin-2 (IL-2) and its receptor (IL-2R), interleukin-4 (IL-4), interleukin-10 (IL-10), interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) was examined. In addition to in situ hybridization, immunohistochemistry was used to identify the subset of cells expressing IL-2 and IL-4 mRNA. Mononuclear cells involved in the minor salivary gland lesions of pSS patients were found to express mRNA for pro-inflammatory cytokines such as TNF-alpha and IL-1 beta, and cytokines involved in the regulation of B- and T-cell function (IL-2 and IL-6). In contrast, only three biopsies from patients with pSS express mRNA of inhibitory cytokines such as IFN-gamma and TGF-beta. Furthermore mRNA for IL-6 and IL-1 beta was also detected in the glandular epithelial cells suggesting that these cells may play a role in the pathogenesis of autoimmune lesion in Sjögren's syndrome. IL-10 mRNA was not detected while IL-4 mRNA was primarily detected in naïve T-lymphocytes of patients with a mild and early lesion. These results suggest that local production of cytokines by both mononuclear and epithelial cells may be involved in the immune-mediated destruction of exocrine glands in patients with pSS.