Progastrin-releasing peptide(31-98) in idiopathic pulmonary fibrosis and sarcoidosis

Gastrin-releasing peptide (GRP) is present in the lung and functions as a growth factor for bronchial epithelial cells and fibroblasts. GRP may stimulate release of cytokines from alveolar macrophages. However, in interstitial lung diseases, the role of GRP has not been clarified, in part because of the instability of GRP. Progastrin-releasing peptide (ProGRP) molecules are the actual GRP gene products. ProGRP molecules contain common extension peptides(31-98) [ProGRP(31-98)], which are not homologous with other proteins unlike GRP. With the ELISA, we measured ProGRP(31-98) concentrations in sera and bronchoalveolar lavage (BAL) fluids from patients with sarcoidosis and idiopathic pulmonary fibrosis (IPF). Significant increased ProGRP(31-98) concentrations were found in sera and BAL fluids from patients with IPF or sarcoidosis when compared with healthy subjects. Serum ProGRP(31-98) values significantly correlated with BAL fluid ProGRP(31-98) values. In IPF and sarcoidosis, the release of the actual GRP gene products is increased in the lung and the bloodstream, and GRP may play a role during the processes of inflammation and remodeling in interstitial lung diseases.