Evaluation of the beneficial efficacy of curcumin on experimental lung fibrosis of adult male albino rats

Abstract

Background Idiopathic pulmonary fibrosis is one of the major types of potentially lethal lung diseases. Curcumin, a natural phenolic compound of Curcuma longa Linn, has anti-inflammatory and antioxidant activity. It is a potent inhibitor of reactive oxygen-generating enzymes. Objective The objective of this study was to evaluate the beneficial efficacy of curcumin on experimental lung fibrosis induced by carbon tetrachloride (CCl4) on adult male albino rats. Methods A total of 32 adult male albino rats were divided into four groups. Group I (four rats) was the control group. Group II (eight rats) was further subdivided into two equal subgroups; subgroup IIA was given corn oil (1mg/kg orally) and subgroup IIB was given curcumin (100mg/kg orally, daily). Group III (10 rats) was given CCl4 (1ml/kg twice a week by intraperitoneal route) and group IV (10 rats) was given curcumin 1 week before and concomitantly with CCl4 injection. Half of the rats of each group were sacrificed after 2 weeks (subgroup A, for short-term study) and the other half were sacrificed after 5 weeks (subgroup B, for long-term study). Lung tissues were processed for light microscope (L/M) and electron microscope (E/M) studies. Moreover, morphometric study was carried out. Results Subgroup IIIA (short-term study) showed a nonsignificant increase in the mean area percentage of collagen fibers and a nonsignificant decrease in the number of type II pneumocytes. Lung sections revealed local areas of interstitial inflammatory reaction, intra-alveolar hemorrhage, edema, and congestion of pulmonary vessels. Subgroup IIIB (long-term study) revealed a highly significant increase in the mean area percentage of collagen fibers and a significant decrease in the number of type II pneumocytes. Lung sections showed diffuse interstitial inflammatory reaction, foci of necrotic alveolar walls, and diffuse interstitial accumulation of collagen. E/M examination revealed degenerative changes and necrosis of type I and II pneumocytes. The alveolar macrophages showed signs of activation. For 2 weeks the curcumin-supplemented group (subgroup VIA) showed an improvement in their histological findings, as revealed by the significant increase in the number of type II pneumocytes that appeared activated. Type I pneumocytes appeared healthy. After 5 weeks (subgroup VIB), there was more improvement as revealed by the highly significant decrease in the mean area percentage of collagen fibers, highly significant increase in the number of type II pneumocytes, and very minimal inflammatory reaction. Conclusion Curcumin has an ameliorating effect against lung damage induced by CCl4. Thus, this study introduces curcumin as one of the natural herbal remedies that could act as a potential preventive agent against interstitial pulmonary fibrosis. Addition of this compound to the food of those individuals who are vulnerable to interstitial pulmonary fibrosis is recommended.