Neurogenic mechanisms in asthma

Neural regulation of the airways is a complex process, but there is evidence to support the presence of activated neural mechanisms in the airways that may lead to bronchoconstriction, airway microvascular leakage and mucus secretion. These features characteristic of asthma underlie the airflow limitation and bronchial hyperresponsiveness in this disease, In addition, the frequent occurrence of a dry cough in asthma also supports a potential role played by neurogenic mechanisms in asthma. How these neural mechanisms can be activated in asthmatic airways remains unclear, In addition, the contribution of neurogenic mechanisms in asthma is still debated. It has been proposed that shedding of the epithelium such as is present in asthma (Laitinen er al, 1985) can expose sensory nerve endings which may then be sensitised by inflammatory mediators such as prostaglandins and certain cytokines, Once sensitised, these nerve endings may be activated by inflammatory peptides such as bradykinin formed from high-molecular weight kininogens (Barnes, 1986).