Objective: To study the effect of gamma-interferon on the protein expressions of interleukin-4 (IL-4) and transforming growth factor-beta(1)(TGF-beta1) on silicotic rats.
Methods: Wistar rats were exposed to lower dose (20 mg) of quartz by intratracheal injection. Next day, the experimental rats were treated with gamma-interferon (1 x 10(5) IU) daily. Rats were killed in 1 month and 2 month to observe the changes of pathology of lung tissue by use of HE and VG staining, and the expressions of IL-4 and TGF-beta1 by use of immunohistochemical technique and quantitative analysis of protein expressions by image analysis system.
Results: (1) The fibrotic degree in silicotic lesions of rat lung was 1/2 approximately 1 grade less in IFN-gamma treated groups than in quartz controls. (2) Quantitative image analysis showed that the integrated optical density (IOD) of IL-4 positive cell in quartz controls in 1 month was (3.33 +/- 1.27) x 10(4) and decreased to (1.99 +/- 0.80) x 10(4) in 2 month, and that of TGF-beta1 positive cell increased from (3.67 +/- 0.63) x 10(4) to (4.90 +/- 1.11) x 10(4); The IOD of IL-4 positive cell in IFN-gamma treated groups was decreased from (2.19 +/- 0.90) x 10(4) to (0.61 +/- 0.22) x 10(4)(P < 0.05), and that of TGF-beta1 positive cell increased from (1.37 +/- 0.31) x 10(4) to (1.76 +/- 0.72) x 10(4) (P < 0.05). At these two time points, the IODof IL-4 and TGF-beta1 positive cell in IFN-gamma treated groups were lower than those in quartz controls (P < 0.05 or P < 0.01).
Conclusion: gamma-interferon may inhibit the expressions of IL-4 and TGF-beta1 in silicotic rats.