Sjögren's syndrome: current therapies remain inadequate for a common disease

Sjögren's syndrome (SS) is a systematic autoimmune disease characterised by dysfunction of the lacrimal and salivary glands. This dryness leads to the symptoms of dry eyes and keratoconjunctivitis sicca, which is painful and may predispose patients to ocular infections. Also, SS patients develop dry mouth, which is uncomfortable and associated with progressive dental disease. SS is divided into secondary SS (where the dryness symptoms are associated with another well defined autoimmune disorder such as rheumatoid arthritis, systemic lupus erythematosus, or scleroderma) and primary SS (where the patients do not fulfil criteria for another well defined associated autoimmune disease). Primary SS has extra glandular organ involvement including lung (interstitial pneumonitis), renal (interstitial nephritis), peripheral and central nervous system manifestations, vasculitis of skin and other organs and increased frequency of lymphoma. This review will concentrate on primary SS. Therapies are divided into agents for topical replacement of deficient secretions (artificial tears, artificial salivas), stimulation of muscarinic M3 receptors (pilocarpine, cevimeline) to increase aqueous secretions, reduction of topical inflammation (topical cyclosporin or corticosteroids for the eye and fluorides or antibacterial varnishes for the mouth) and modification of the immune response in a manner similar to treatment of systemic lupus (antimalarial drugs, methotrexate, cyclophosphamide and perhaps newer agents such as leflunomide or TNF inhibitors).