Small airway disease and chronic obstructive pulmonary disease are common in primary Sjögren's syndrome (pSS). However, the underlying inflammatory mechanisms behind pSS-associated airway disease have not been studied in detail. We therefore wanted to study cytokine and leucocyte levels in induced sputum in never-smoking patients with pSS.
Induced sputum cytokines and leucocytes were assessed in 20 never-smoking patients with pSS and 19 age- and gender-matched population-based controls. In addition, pulmonary function, disease activity, respiratory symptoms, and inflammatory and serological features of pSS were assessed.
B-cell activating factor (BAFF), interleukin-6 (IL-6) and IL-8 were significantly increased in induced sputum in pSS patients compared to population-based controls, while IL-1β, interferon-α, and tumour necrosis factor-α levels and leucocytes were not. The proportion of lymphocytes and BAFF levels in induced sputum correlated significantly in pSS patients. However, cytokine levels in induced sputum were not associated with pulmonary function tests, disease activity, respiratory symptoms, or serological features of pSS.
The increase in BAFF, IL-6, and IL-8 in induced sputum suggests a specific ongoing inflammatory disease process in the airways in pSS patients. Its association with pSS-associated airway disease needs to be further examined in future larger studies.