Role of free Radicals

Lung Diseases

A range of lung conditions have been associated with oxidative stress including lung cancer, emphysema, and cystic fibrosis. The lungs are prone to oxidative damage as they are exposed to an oxygen rich environment and are continually exposed to environmental toxins. Prolonged exposure to oxygen and environmental toxins stimulate phagocytic cells in the lung to generate ROS and free radicals, which cause lipid per-oxidation. Oxidative attack on the respiratory tract lining causes cell injury and tissue damage, which in turn leads to further stimulation of phagocytes for the production of ROS . Some lung conditions, for example, cystic fibrosis, cause increased levels of free iron, decreased levels of glutathione and selenium and increased oxidative damage to DNA. The fluid contains low molecular weight antioxidants e.g. ascorbic acid, glutathione, uric acid, albumin, alpha-tocopherol, metal binding proteins, antioxidant enzymes and glycoconjugates, which can act as potent free radical scavengers. Treatment of lung disease patients with antioxidants may offer protection against the disease, including the idea of antioxidants in aerosol form for direct application to the respiratory tract lining. However, this form of administration may simply result in decreased antioxidant production by the phagocytes in the respiratory lining and may not serve to increase the antioxidant levels. It is currently unknown whether oral administration of vitamins has any beneficial effects for lung disease patients, as high levels of vitamins A and ß-carotene could be potentially harmful.

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