CCL21 and IP-10 as blood biomarkers for pulmonary involvement in systemic lupus erythematosus patients

Biomarkers for pulmonary manifestations in systemic lupus erythematosus (SLE) are missing. Plasma samples of nine SLE patients with known pulmonary involvement (SLE_pulm) and nine SLE patients without pulmonary involvement (SLE) were tested by multiplex microarray analysis for various cyto- and chemokines. Significantly decreased lung function paramters for forced vital capacity (FVC), total lung capacity (TLC), diffusion capacity for carbon monoxide (DL_CO) and diffusion of CO corrected on lung volume (KL_CO) were observed in SLE_pulm as compared to SLE patients. CC chemokine ligand 21 (CCL21) and interferon gamma-induced protein 10 (IP-10) levels were significantly higher in SLE_pulm, than in patients without pulmonary manifestations. CCL21 correlated negatively with DL_CO ( r = -0.73; p < 0.01) and KL_CO ( r = -0.62; p < 0.01), while IP-10 with FVC and forced expiratory volume one second. Receiver Operating Characteristics (ROC) analysis confirmed high sensitivity and specificity for the separation of SLE patients with and without pulmonary involvement for the chemokines CCL21 (Area Under Curve (AUC): 0.85; sensitivity%: 88.90; specificity%: 75.00; p < 0.01) and IP-10 (AUC: 0.82; sensitivity%: 66.67, specificity%: 100; p < 0.01). Pleuropulmonary manifestations in SLE patients associated with lung functional and DL_CO/KL_CO changes and were associated with significant increase in CCL21 and IP-10. These chemokines might serve as potential biomarkers of lung involvement in SLE patients.