ABSTRACT
Idiopathic pulmonary fibrosis (IPF) and bronchiolitis obliterans with organizing pneumonia (BOOP) are interstitial lung diseases of unknown pathogenesis. Alveolar macrophages play a major role in the regulation of the inflammatory response in these diseases through their ability to produce cytokines that modify the inflammatory response. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) exhibit proinflammatory and anti-inflammatory actions, respectively, and thus an imbalance in the expression of these cytokines may contribute to the pathogenesis of IPF and BOOP. Therefore, we quantified IL-10 and TNF-alpha mRNA levels in alveolar macrophages obtained by bronchoalveolar lavage (BAL) from patients with IPF and BOOP and in normal healthy volunteers. The level of TNF-alpha mRNA in macrophages obtained from IPF and BOOP patients was not significantly different from normal healthy subjects. However, macrophages from patients with IPF and BOOP expressed increased levels of IL-10 mRNA compared with healthy controls. In addition, stimulation of alveolar macrophages with lipopolysaccharide in the presence of a neutralizing anti-IL-10 antibody augmented the production of TNF-alpha over that seen in the absence of anti-IL-10 antibody, suggesting that the increased expression of IL-10 by alveolar macrophages may act to control the expression of TNF-alpha. Paradoxically, measurement of IL-10 protein in cell-free BAL fluid revealed lower amounts of the protein in patients with IPF and BOOP compared with healthy controls.
Subject(s)
Cryptogenic Organizing Pneumonia/immunology , Interleukin-10/biosynthesis , Macrophages, Alveolar/immunology , Pulmonary Fibrosis/immunology , Transcription, Genetic , Tumor Necrosis Factor-alpha/biosynthesis , Adult , Base Sequence , Bronchoalveolar Lavage , Bronchoalveolar Lavage Fluid/cytology , Cryptogenic Organizing Pneumonia/pathology , DNA Probes , Eosinophils/pathology , Female , Humans , Interleukin-10/analysis , Lymphocytes/pathology , Macrophages, Alveolar/pathology , Male , Middle Aged , Molecular Sequence Data , Neutrophils/pathology , Polymerase Chain Reaction , Pulmonary Fibrosis/pathology , RNA, Messenger/biosynthesis , Reference Values , Regression AnalysisABSTRACT
Recent evidence suggests that the alveolar macrophage-derived cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6) play important roles in granulomatous diseases. Our objective was to quantify the mRNA for these cytokines in beryllium disease, a human granulomatous disease of known etiology. We hypothesized that alveolar macrophages and bronchoalveolar lavage fluid from patients with beryllium disease and sarcoidosis would express increased levels of mRNA and proteins, respectively, for TNF-alpha, IL-1 beta, and IL-6 compared with those of normal individuals. We performed bronchoalveolar lavage and used a quantitative polymerase chain reaction to determine alveolar macrophage-derived cytokine gene expression. We determined lavage fluid cytokine levels by enzyme-linked immunosorbent assay. In patients with beryllium disease (n = 23), we observed elevated macrophage mRNA expression for TNF-alpha and IL-6 when compared with that of normal subjects (n = 7). Sarcoidosis patients (n = 6) also had increased expression for TNF-alpha and IL-6 compared with that of normal volunteers. IL-1 beta expression was similar in all three groups. In patients with beryllium disease (n = 39), lavage fluid TNF-alpha concentration was higher than that of 16 normal subjects. Lavage fluid IL-1 beta and IL-6 levels did not differ among the groups. This is the first report of macrophage cytokine expression in beryllium disease. These novel findings suggest that macrophage expression of TNF-alpha and IL-6 may be important in the human granulomatous inflammatory response.
