Role of Cytokines in Pathophysiology of Asthma

The worldwide incidence, morbidity and mortality of asthma are increasing dramatically. It is one of the most common disorders encountered in clinical medicine in both children and adults. It affects approxi-mately 5% of the adult population in the western world and its reported incidence is increasing vigorously in many developed nations. A network of novel mediators known as ‘pleiotropic cytokines’ regulate the intermittent airway inflammation, bronchial smooth muscle hyperreactivity and bronchoconstricion under-lying asthma. Preclinical and clinical data suggest that, the pathophysiological features of asthma are thought to result from the aberrant expansion of cytokines and chemokines. Cytokines are small extracel-lular signaling protein produced by different cells and possess a wide spectrum of biological activities due to their redundancy and pleiotropic properties. They are critical to the functioning of both innate and adap-tive immune responses. Cytokines and their receptors exhibit very high affinity for each other. Because of this high affinity, picomolar concentrations of cytokines can mediate a biological effect. The major groups of cytokines are lymphokines, proinflammatory cytokine, inhibitory cytokines and growth factors. Patho-physiology of asthma is still poorly understood and its cause remains unknown. On this basis, this review will concentrate on the synthesis, release and functional role of each cytokine in the pathophysiology of asthma.