Abstract
Asthma is characterized by repeated episodes of airway obstruction and an ongoing cycle of airway inflammation. Reactive oxygen species (ROS) produced by inflammatory cells in the lung play a key role in the pathogenesis as well as amplification of inflammation in asthmatic airways. Several enzymatic and non-enzymatic antioxidants are available in the lung and systemic circulation to counteract ROS-mediated damage on various biomolecules such as lipid membranes, proteins, and DNA; however during asthmatic inflammation these defenses are overwhelmed due to excessive production of ROS thereby leading to inflammatory events in the airways/systemic circulation. ROS-mediated damage may result in increased vascular permeability, mucus hypersecretion, smooth muscle contraction, epithelial shedding and impairment in the responsiveness of β-adrenergic receptors. Strategies aimed to boost the endogenous antioxidants either through dietary or pharmacological intervention to redress oxidant-antioxidant imbalance in asthma is the current area of research in many laboratories throughout the world. This review aims at providing a comprehensive overview of the available literature on oxidative stress and antioxidants imbalance in asthma with a focus both on lung and blood components and bring forth correlations between lung/blood oxidative stress/antioxidant parameters and lung function.