Background and aim: Characterization of the biologic effects of Th1 cytokines will enhance the understanding of idiopathic pulmonary fibrosis (IPF) pathogenesis and treatment selection. Th1 response is characterized by increased expression of IFN-gamma, interleukin (IL)-12 and IL-18. The present study aims to evaluate the role of Th1 cytokines and their possible changes in the bronchoalveolar lavage fluid (BALF), before and after treatment with IFN-gamma-1b or colchicine.
Patients and methods: We studied prospectively 10 patients (8 male, 2 female) of median age 67 yr with histologically confirmed IPF/UIP. Patients were randomly assigned to receive either IFN-gamma-1b 200 microg sc (5 patients) or colchicine 1 mg qd (5 patients) plus prednisone 10 mg qd. BALF IL-12 and IL-18 levels were measured before and after treatment.
Results: BALF IL-12 levels before and after treatment did not differ significantly between the two treatment groups. However, BALF IL-18 levels were significantly decreased after treatment with IFN-gamma-1b (mean +/- SD, 58.4 +/- 15.6 pg/mL vs 42.8 +/- 4.90 pg/mL, p < 0.05). A significant difference was also found after treatment with colchicine (mean +/- SD, 66.8 +/- 36.9 pg/mL vs 42.6 +/- 1.08 pg/mL, p < 0.01). A significant correlation was found between IL-18 BALF levels and the BALF neutrophils (r = 0.75, p = 0.024).
Conclusion: Our data suggest the potential role of IL-18 as an inflammatory marker in the pathogenetic pathway of IPF such as its possible downregulation by IFN-gamma-1b treatment. Further studies are needed in a higher number of patients in order to define the precise role of both cytokines during the immunoregulatory response with IFN-gamma-1b.