Morphometric analysis of insulin-like growth factor-I localization in lung tissues of patients with idiopathic pulmonary fibrosis

• Published in: American journal of respiratory and critical care medicine Vol. 158; no. 5; pp. 1626 - 1635
• Main Authors: UH, S.-T, INOUE, Y, KING, T. E, CHAN, E. D, NEWMAN, L. S, RICHES, D. W. H
• Format: Journal Article
• Language: English
• Published: New York, NY American Lung Association 01.11.1998
• Subjects: Adult; Antigens, CD - analysis; Antigens, Differentiation, Myelomonocytic - analysis; Biological and medical sciences; Cell Division; Cilia - pathology; Collagen - biosynthesis; Epithelial Cells - pathology; Female; Fibroblasts - pathology; Humans; Immunohistochemistry; Insulin-Like Growth Factor I - analysis; Insulin-Like Growth Factor I - physiology; Lung - pathology; Macrophages, Alveolar - pathology; Male; Medical sciences; Middle Aged; Monocytes - pathology; Pneumology; Pulmonary Alveoli - pathology; Pulmonary Fibrosis - pathology; Respiratory system : syndromes and miscellaneous diseases; Human; Lung disease; Pathophysiology; Respiratory disease; Immunocytochemistry; Lung; Idiopathic; Quantization; Exploration; Insulin like growth factor; Analysis; Fibrosis; Morphometry; Localization; Macrophage
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/ajrccm.158.5.9804025

Insulin-like growth factor-I (IGF-I) has been implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF) through its ability to stimulate fibroblast proliferation and collagen synthesis. However, although alveolar macrophages (AM) have been shown to express this growth factor, it is likely to also have other cellular sources. We sought to determine the distribution of cells expressing IGF-I in lung tissues obtained from 10 patients with IPF and 10 control subjects. We evaluated the levels of IGF-I and of a macrophage/monocyte-specific marker, CD68, by immunocytochemistry and quantified by morphometry. In control subjects, IGF-I was localized principally to AM. In contrast, in IPF patients IGF-I was localized to AM, interstitial macrophages, alveolar epithelial cells, and ciliated columnar epithelial cells. The normalized volume density (Vv) of IGF-I-positive (IGF-I+) interstitial macrophages (Vv of IGF-I+ interstitial macrophages/Vv of lung x 100) was increased in patients with IPF as compared with control subjects, and the ratio of Vv of IGF-I+ to CD68(+) interstitial macrophages correlated with: (1) the degree of clinical impairment in patients with IPF as measured by their clinical-radiologic-physiologic (CRP) score; and (2) the degree of collagen deposition in the interstitium. These findings support a role for interstitial macrophages as a source of IGF-I in IPF.