Exhaled cytokines in systemic lupus erythematosus with lung involvement

INTRODUCTION An inflammatory process in systemic lupus erythematosus (SLE) affects many organs including the lungs. Interleukin (IL) 6 and IL-10 are suggested to play an important role in the pathogenesis of SLE. OBJECTIVES The aim of the study was to evaluate IL-6 and IL-10 levels in the exhaled breath condensate (EBC) and bronchoalveolar lavage fluid (BALF) of patients with and without pulmonary involvement in SLE. PATIENTS AND METHODS The study included 34 patients with SLE and 31 healthy controls evaluated using high-resolution computed tomography, pulmonary function tests, the Systemic Lupus Activity Measure (SLAM), and IL-6 and IL-10 measurement (by an enzyme-linked immunosorbent assay) in the BALF and EBC. RESULTS The mean IL-6 and IL-10 concentrations in the BALF and the IL-10 concentration in the EBC were higher in patients with SLE compared with healthy controls (4.03 +/- 8.3 vs. 0.62 +/- 1.2 pg/ml, P < 0.0001; 5.54 +/- 1.85 vs. 0.00 +/- 1.82 pg/ml, P < 0.0001; 8.28 +/- 2.7 vs. 0.00 +/- 1.68 pg/ml, P < 0.0001, respectively). The IL-10 level in the EBC correlated with SLE activity (r = -0.40, P = 0.019). The SLAM was significantly higher and the total lung capacity was significantly lower in patients with pulmonary manifestation of SLE compared with those without such complications (8.00 +/- 3.17 vs. 6.00 +/- 2.31, P = 0.01; 88.00 +/- 28.29 vs. 112 +/- 21.08 % predicted, P = 0.01; respectively). In patients with pulmonary involvement, correlations were observed between the IL-10 level in the EBC and the percentage of lymphocytes in the BALF (r = -0.5, P = 0.04). CONCLUSIONS Our results indicate that IL-6 and IL-10 are involved in the pathogenesis of SLE. The measurement of IL-10 in the EBC may be a useful biomarker of SLE activity. It is likely that IL-10 protects against pulmonary manifestations of SLE.