Effectiveness of rosiglitazone on bleomycin-induced lung fibrosis: Assessed by micro-computed tomography and pathologic scores

Peroxisome proliferator-activated receptor-γ (PPARγ) agonists exhibit potent anti-fibrotic effects in the lung and other tissues. Recently, micro-computed tomography (CT) has been a useful tool for the investigation of lung diseases in small animals and is now increasingly applied to visualize and quantify the pulmonary structures. However, there is little information on the assessment for therapeutic effects of PPARγ agonists on the pulmonary fibrosis in mice using micro-CT. This study was aimed to determine the capability of micro-CT in examining the effects of rosiglitazone on pulmonary fibrosis. We used a murine model of bleomycin-induced lung fibrosis to evaluate the feasibility of micro-CT in evaluating the therapeutic potential of rosiglitazone on pulmonary fibrosis, comparing with pathologic scores. On micro-CT findings, ground glass opacity (80%) and consolidation (20%) were observed predominantly at 3 weeks after the instillation of bleomycin, and the radiologic features became more complex at 6 weeks. In bleomycin-instilled mice treated with rosiglitazone, the majority (80%) showed normal lung features on micro-CT. Radiological-pathologic correlation analyses revealed that ground glass opacity and consolidation were correlated closely with acute inflammation, while reticular opacity was well correlated with histological honeycomb appearance. These results demonstrate that rosiglitazone displays a protective effect on pulmonary fibrosis in mice and that the visualization of bleomycin-induced pulmonary fibrosis using micro-CT is satisfactory to assess the effects of rosiglitazone. It implies that micro-CT can be applied to evaluate therapeutic efficacies of a variety of candidate drugs for lung diseases.