The role of CCR9-expressing T cell subsets in the immunopathology of primary Sjögren's syndrome

Abstract

In this thesis research on CCR9-expressing T cell subsets in primary Sjögren’s syndrome (pSS) is described. pSS is a chronic autoimmune disease in which most patients have complaints of dryness of eyes and mouth, fatigue, and pain in muscles and joints. The dryness arises from inflammation of the glands that produce tear fluid and saliva. This inflammation occurs spontaneously, meaning that the immune system reacts as though an infection with a bacteria or virus needs to be eradicated, whereas this is not the case. In fact, healthy cells of the patient get inflamed and damaged. Research described in this thesis shows that in the blood of patients with pSS different types of T cells that express protein CCR9 are elevated as compared to healthy controls. By far most T cells do not express CCR9. Not only the numbers of CCR9-expressing T cells are elevated in pSS patients, these cells also display more aggressive potential in patients, e.g. by causing more inflammation. Apart from the T cell research, in this thesis we’ve also performed a pilot study to research different autoimmune diseases, as pSS, scleroderma (SSc) and lupus (SLE), using a new minimally-invasive technique. Sebum was sampled from the skin using special tape, after which the sebum was broken into smaller pieces (metabolite ions). Metabolite ions found in the different patient groups were compared to each other and to those from healthy controls. The biggest difference in metabolite ions was found between healthy controls and SSc patients. Furthermore, between patients with SSc and pSS the overlap in aberrant metabolite ions was high. This first study shows potential as new, non-invasive strategy for finding biomarkers in these different disease and will be further studied.