Sjögren's syndrome (SS) is the most common autoimmune disease with dry eye (DE) syndrome and some systemic lupus erythematosus (SLE) patients are also with DE syndrome. The occurrence of immune-related DE disease is closely related to T helper (Th) 17 cells in SS patients, and SLE patients have abnormal levels of multiple Th17 cell-related cytokines in their blood. However, the degree of expression of these cytokines in blood differs from that in tears. We hypothesised that the occurrence of DE symptoms in SLE and SS patients may be related to Th17 cells.
In this study, Th17 cell-related cytokines, including interleukin (IL)-1β, IL-2, IL-4, interferon-γ, IL 6, IL-8, IL-17F, tumour necrosis factor (TNF)-α, IL-21, IL-22, and IL-23 were analysed in tear samples of DE, SLE, and SS patients. Ocular surface examinations for patients with DE symptoms, including tear secretion test (Schirmer I Test, SIT) and tests for ocular surface disease index (OSDI), tear break-up time (BUT), and corneal fluorescein stain (CFS), were performed and compared between the following patient groups: normal healthy people (control group, n=30), patients with simple DE disease (DE group, n=13), SLE patients with DE disease (SLE group, n=17), and SS patients with DE disease (SS group, n=18).
The expression of Th17 cell-related cytokines in each tear sample was analysed using Luminex assay. The SIT and BUT scores of the SLE group were lower than those of the control (p<0.001) and DE (p<0.05) groups. However, SIT, BUT, CFS, and OSDI scores were not significantly different between SLE and SS patients. TNF-α, IL-6, IL-8, and IL-21 levels in tear samples were higher in DE, SLE, and SS patients (p<0.05) than in control individuals. IL-2 and IL-4 levels in tear samples of SLE patients were higher than DE (p<0.001) but lower than the control (p<0.001) group patients. IL-23 levels in tear samples of DE, SLE, and SS patients were all lower than those in the control group (p<0.001). SIT, BUT, CFS, and OSDI results showed that the DE symptoms of SLE and SS patients were more severe than those of the DE group.
It is known that cytokine expression levels in tears are different from those in blood. Abnormal regulation of the Th17 cell pathway may be related to the occurrence of DE disease in SLE and SS patients, and Th17 cell-related cytokines, such as IL-8 and IL-21, may be potential therapeutic targets for treating SLE or SS DE disease.