Localization of type I procollagen gene expression in silica-induced granulomatous lung disease and implication of transforming growth factor-β as a mediator of fibrosis

Thomas J. Mariani, Jill D. Roby, Robert P. Mecham, William C. Parks, Edmond Crouch, Richard A. Pierce

Research output: Contribution to journalArticle

49 Scopus citations

Abstract

We have used the silica-induced model of pulmonary injury in the rat to study the pattern of collagen expression in granulomatous lung inflammation. A single intratracheal instillation of silica into adult rats resulted in granulomatous inflammation leading to fibrosis and alveolar proteinosis. The development of disease in these animals was characterized over a 27-day period after treatment by means of histological, biochemical, and molecular analyses. Biochemical analyses indicated that significant increases in the weights of silicotic lungs were due to elevated amounts of DNA and total protein. Analysis of hydroxyproline content showed a 15-fold increase in this amino acid in silicotic lungs, confirming the development of a fibrotic reaction. In situ hybridization for type I procollagen mRNA displayed increased gene expression in the parenchyma, conducting airways, and vasculature of silicotic rats. Within the parenchyma, type I procollagen was expressed uniquely within granulomatous lesions. Immunohistochemistry indicated type I procollagen was being expressed by an α-smooth muscle actin-negative population of cells. Immunolocalization of extracellular transforming growth factor-β showed coincident temporal and spatial overlap with type I procollagen expression, implicating this cytokine as a mediator of collagen gene expression in this model.

Original languageEnglish
Pages (from-to)151-164
Number of pages14
JournalAmerican Journal of Pathology
Volume148
Issue number1
StatePublished - Jan 1 1996

Fingerprint Dive into the research topics of 'Localization of type I procollagen gene expression in silica-induced granulomatous lung disease and implication of transforming growth factor-β as a mediator of fibrosis'. Together they form a unique fingerprint.

  • Cite this