Introduction: Aluminum chloride is the most abundant metal present on the earth's crust. It is found in our daily life as in drinking water, soil and in commonly used cosmetics. The lung epithelium is the site for aluminum chloride accumulation. Propolis is wax-like bee product. It has a powerful anti-inflammatory antioxidant property.
Objectives: Evaluation of aluminum chloride toxicity on lung tissue and the possibility of Propolis to play a protective role.
Materials and Methods: Fifty adult male albino rats were divided into five equal groups received treatment for 6 weeks: (I) Control group received distilled water (II) Propolis group "50mg/kg ". (III) Aluminum chloride group "475mg/kg". (IV) Recovery group" kept untreated". (V) Propolis and aluminum chloride group. Finally, all animals were sacrificed. Lung samples were obtained for histological and immunohistochemical studies. Data was statistically analyzed.
Results: Groups (I& II) showed normal structure of lung tissues. Aluminum chloride group (III) revealed distorted lung tissues. Some alveoli were collapsed and the others showed compensatory dilatation. Lung tissue had numerous hemosiderin granules. Pneumocyte II showed condensed nucleus, cytoplasmic vacuolations, distended irregular mitochondria, dilated rough endoplasmic reticulum and degeneration of their lamellar bodies. There was thickening in the inter-alveolar septa, numerous inflammatory infiltrate and eosinophilic materials. Blood vessels were congested and surrounded by inflammatory cells. The bronchioles showed distortion. Marked collagen fibers and numerous accumulations of mast cells in connective tissue septae were detected. A significant decrease in BCL2 immune expression was noticed. These changes were moderately alleviated in the recovery group. Co-administration of Propolis with aluminum chloride restored lung tissue integrity.  Conclusion: Aluminum chloride induces marked lung tissue damage via, fibrosis and apoptosis. These changes can be alleviated moderately by stopping treatment for 2 weeks and markedly by combined treatment with Propolis. So we recommend Propolis supplementation for people exposed to aluminum chloride.