Background and aim of the work: In vitro studies have suggested that fibroblasts from idiopathic pulmonary fibrosis (IPF) may have an impaired induction of cyclooxygenase (Cox)-2. We have investigated Cox-1 and Cox-2 expression in lung tissue from IPF.
Methods: Cox-1 and Cox-2 expression were determined using RT-competitive PCR and immunohistochemistry in pulmonary biopsies from IPF (n = 22), chronic obstructive pulmonary disease (COPD) (n = 13), and lung tissue from subjects undergoing pleurodesis for spontaneous pneumothorax (control group, n = 17).
Results: Immunohistochemical analysis showed that the score of Cox-2 positive cells was higher in COPD (1 +/- 0) with respect to fibrosis (0.37 +/- 0.1, p < 0.05) and controls (0.57 +/- 0.2). There were no differences between fibrosis and controls in Cox-2 positive cells. The expression of Cox-2 mRNA was significantly higher in COPD (3.26 +/- 0.72 x 10(6) molecules cDNA/microg total RNA) in comparison to IPF (0.57 +/- 0.17) and controls (0.54 +/- 0.16) (p < 0.001). After IL-1beta stimulation (1-10 ng/ml) Cox-2 mRNA basal expression increased significantly in controls (from 35 +/- 12 to 94 +/- 4 x10(6) molecules cDNA/microg total RNA, p < 0.01) and in COPD (from 38 +/- 8 to 92 +/- 3, p < 0.01). In contrast, no significant changes in Cox-2 mRNA expression were found in IPF (from 30 +/- 12 to 43 +/- 16).
Conclusions: Our results suggest that differences in Cox-2 expression may play a role in the regulation of inflammatory responses in lung diseases. Excessive activity is associated with the development of chronic obstructive lung disease, while a limited activation following pro-inflammatory stimulation might contribute to fibrogenic responses.