Unlike other rheumatic diseases, acute phase reactants such as C-reactive protein and erythrocyte sedimentation rate are not diagnostic for patients with Spondyloarthropathies (SpA). Also, it is not possible to monitor disease activity with these tests. On the other hand, HLA-B27 positivity varies between races, and 8% of the normal population is HLA-B27 positive. In this manner, new biomarkers for endorsing the diagnosis and monitoring the disease activity are necessary.
In recent years Raftlin, a significant lipid raft protein responsible for transmembrane signal transmission, was found. It has been discovered that the Raftlin protein has two subtypes (Raftlin-1 and Raftlin-2), and in transgenic mice without RAFTLIN genes, T-cell-dependent immunity has been altered.
Cytokine production, especially IL-17, is diminished in T cells with the lack of Raftlin protein, while it is increased in T cells, including transgenic Raftlin. This condition is associated with TCR-related signaling pathways. Particularly, Lck protein occurrence in lipid raft is increased with Raftlin overexpression, while it is diminished with absence. Regarding this, Raftlin is thought to modulate TCR signaling, thus altering the T-cell mediated immunity.
Acute phase reactants are not sensitive for diagnosing and assessing disease activity. This may lead to a diagnostic delay of up to 9 years. The investigators hypothesize that Raftlin-1, thought to have a regulatory role in TH17 function and IL-17-mediated immunity, may be a novel biomarker for showing inflammation-related clinical features.
