Neurotrophins Implications in Primary Sjögren Syndrome

Neurotrophins (NTs) constitute a family of growth factors, which regulated differentiation, proliferation, and survival of both neuronal cells and astrocytes. In recent years, several studies have provided evidences that the cellular effects of NGF " Nerve Growth Factor ", BDNF " Brain-Derived Neurotrophic Factor " and NT-3 are not limited to the nervous system. Indeed, neurotrophins and their receptors are widely expressed on non neuronal cells. Data concerning the implication of NTs and their receptors in the immune system maturation and in the regulation of normal and pathological immune responses are numerous and suggest the existence of a specific "neuro-immunomodulation" through these neuropeptides. The aim of the study is to compare Sjögren's syndrome systemic activity to seric, lymphocytic and conjunctival levels of NTs (i.e NGF, BDNF and NT-3). A preliminary study has previously pointed out the link between high BDNF seric levels and Sjögren's systemic activity. The increased levels of BDNF were correlated to T cell activation. A similar correlation between high NGF level and hypergammaglobulinemia was also pointed out.

2 supplementary blood sample for determination of seric and lymphocytic NT profile will be added to a standard biological analysis done for pSS follow- up. Salivary sicca syndrome will be evaluated with un-stimulated salivary flow rate. Saliva fluid will be collected from NTs levels determination (ELISA). Ocular sicca syndrome will be evaluated by Schirmer tests and Lissaline green test. A conjunctival cytological impression will be done in order to determine NTs conjunctival production by flow cytometry.