Serum progranulin levels in idiopathic pulmonary fibrosis and other interstitial lung diseases

Abstract

Progranulin (PGRN) is a PC cell-derived growth factor that is shown to be involved in the regulation of cellular proliferation, cell differentiation, tumorigenesis and inflammatory processes. Its elevated levels have been reported in liver fibrosis and in acute interstitial lung disease associated with dermatomyositis. Its role in the pathogenesis of idiopathic pulmonary fibrosis (IPF) and other non-IPF interstitial lung disease (ILD) has not been investigated yet. The serum levels of PGRN were measured by enzyme-linked immunosorbent assay in patients with stable IPF (n =24); other ILD (sarcoidosis, connective tissue disease associated ILD, hypersensitivity pneumonitis) (n =30) and healthy control subjects (n =12). HRCT was performed in all patients. We assessed the correlation between the serum PGRN levels and lung function parameters (FVC, diffusing capacity), exercise tolerance (6-minute-walk test (6 MWT)) and severity of IPF (GAP score). Serum PGRN levels were significantly higher in non-IPF ILD patients than in healthy controls (p=0.007) and in IPF patients (p=0,037). However the measured levels in IPF patients were comparable with the levels of healthy subjects (p=0.528). The serum PGRN levels did not correlate with GAP index, forced vital capacity, diffusion capacity or 6 MWT distance in any of the groups. Elevated serum PGRN may be associated with the presence of non-IPF ILD, but not with stable IPF, therefore maybe useful tool in differential diagnosis. Clarification of the relationship between progranulin levels and activity of non-IPF ILD, IPF progression and antifibrotic treatment effect requires further research.