Protective Effects of Bromelain against Cadmium-Induced Pulmonary Intoxication in Rats: A Histopathologic and Cytologic Study

Bromelain is the active substance of pineapple with a variety of therapeutic properties. In this study, the possible protective effects of bromelain were assessed against cadmium acute intratracheal exposure and its bronchopulmonary cytologic and histopathologic consequences. For this purpose, the following treatments were performed on 11 groups of Wistar rats: group 1 was negative control; groups2 and 3 received Cadmium Chloride (CdCl2) 400 µg/rat intratracheally and sampled after 5 and 10 days, respectively; groups4 and 5received bromelain 20 mg/kg orally (PO) from 14 days before until 5 and 10 days after CdCl2 instillation, respectively; groups6 and 7received bromelain 40 mg/kg from 14 days before until 5 and 10 days after CdCl2 instillation, respectively; group 8received bromelain 40 mg/kg for 24 days; groups9 and 10: celecoxib 25 mg/kg PO from 1day before until 5 and 10 days after CdCl2 instillation, respectively; group 11 received celecoxib for 11 days. Cytologic evaluation of bronchoalveolar lavage fluid revealed that intratracheal cadmium administration resulted in a significant rise in total cell count, epithelial cells, neutrophils, and eosinophils, 5- and 10-days post-exposure. Treatment with bromelain either in low or high doses in cadmium-exposed rats resulted in a significant reduction of neutrophil count. Bromelain treatment could not completely prevent or recover interstitial pneumonia and fibrinous bronchopneumonia in cadmium exposed rats. However, administration of low doses resulted in a significant decrease of semi quantitative histopathologic scores, including pneumonia and cellular infiltration indices. In conclusion, bromelain may help to improve the cytological and histopathological complications following cadmium intoxication in the lungs.