Expression of Toll-Like Receptors in Peripheral Blood Mononuclear Cells of Patients with Primary Sjögren's Syndrome.

Toll-like receptors (TLRs) are pattern recognition receptors important for the detection of pathogen-associated molecular patterns. They are localized on cellular membranes, on either the cell surface or the endosomes. Primary Sjögren's syndrome (pSS) is a systemic rheumatic autoimmune disease characterized by lymphocytic infiltrations in exocrine glands resulting in dryness in eyes and mouth. In a majority of patients, autoantibodies against Ro/SSA and/or La/SSB are present. Here we analysed mRNA levels of TLR1-10 and protein expression levels of most of them in human peripheral blood mononuclear cells from 20 patients with pSS and 20 healthy controls. Patients with pSS showed significantly higher mRNA levels of TLR8 than controls, while transcript levels of TLR9 were significantly lower. At the protein level, patients with pSS expressed significantly less TLR5 and significantly more TLR7 compared with healthy controls. TLR7 and 8 are encoded by genes localized on the X chromosome, which is especially interesting regarding the gender imbalance of pSS. The differential expression of various TLR in PBMC of patients with pSS might contribute to an altered recognition of nucleic acids, eventually resulting in the development of autoimmune disease.