Sjögren’s syndrome (SS) was discovered by the Swedish ophthalmologist known as Henrik Sjögren. This condition is defined as a systemic rheumatic autoimmune disease affecting the exocrine glandular function, where the salivary and lacrimal (tear) glands are the primary sites of inflammation. Here, mononuclear cells infiltrate the glandular epithelium, leading to destruction and dysfunction of the glands. Hence, SS patients often suffer from the common symptoms of dry mouth and dry eyes (xerostomia and keratoconjuctivitis sicca), in addition to general symptoms of systemic inflammation such as fatigue, muscle and joint aches, low-grade fever and clinical depression.
SS can either exist on its own i.e. pSS, or as secondary (sSS) in combination with other rheumatic autoimmune diseases, most commonly rheumatoid arthritis and systemic lupus erythematosus. Moreover, approximately one third of pSS patients develop extra-glandular manifestations, including different skin manifestations, arthritis, leucopenia and vasculitis. The prevalence of pSS in the general population is very low. It mostly affects post-menopausal women, with a female to male ratio of 9:1 and a peak incidence at 40-50 years of age. Much like other autoimmune diseases the cause of SS remains unknown. However, it has been suggested that genetic predisposition, hormonal factors and viral agents, such as Epstein-Barr virus and retroviruses, could be potential triggers in disease development.