Abstract
Background: Sarcoidosis is a systemic granulomatous disease of unknown etiology with a significant heterogeneity in organ manifestations, severity, and clinical course. Subjects with sarcoidosis share several features such as, non-necrotizing granuloma, hypergammaglobulinemia, increased local and circulating inflammatory cytokines, such as interleukin (IL)-6, IL-18, and interferon gamma (IFN-γ). Macrophage migration inhibitory factor (MIF) is a pluripotent chemokine produced by various cell types. The expression of MIF at sites of inflammation suggests a regulatory role in the function of macrophages. The objective of this study was to investigate the role of MIF in the serum and bronchoalveolar lavage (BAL) fluid of sarcoidosis patients in association with clinical features and other cytokines. Methods: Sera and BALs of sarcoidosis patients (n=55) were collected at the time of diagnosis and patients were followed longitudinally for 3 years. Additionally, fifteen healthy controls participated in the study. The medical records of all patients including, demographics, radiography stages, pulmonary function tests, and organ involvements were recorded. The levels of MIF, IL-18, IL-10, IL-6, IFN-γ and lysozyme in serum and BAL samples were measured by ELISA. Statistical analyses were performed using SPSS software. Results: Serum MIF had a remarkable positive correlation with IL-10 and IFN-γ but had a negative correlation with serum IgG levels. Importantly, longitudinal follow-up showed a positive correlation between MIF and % predicted diffusion capacity (%DLCO) at 3-year. Serum IL-18 had a significant positive correlation with serum lysozyme, but a negative correlation with % predicted total lung capacity at 3-year follow up. We identified two groups of sarcoidosis subjects with distinct clinical and cytokine features. A group with prominent extrapulmonary involvement, and low serum MIF, IL-10 and IFN-γ levels and a group with elevated serum MIF, IL-10 and IFN-γ levels. Moreover, we found a negative correlation between BAL IL-18 and BAL MIF in sarcoidosis subjects.Conclusions: Patients with low serum MIF, IL-10 and IFN-γ levels has severe and mostly extrapulmonary sarcoidosis with elevated lysozyme and IL-18 levels. Our work provides understanding of phenotypic diversity in association with heterogeneity in cytokine landscape in sarcoidosis.