Pulmonary vasculature and critical asthma syndromes: a comprehensive review

One of the important factors and consequences in persistent asthma is the change in the vasculature of the airways and lung parenchyma. These changes could contribute to worsening asthma control and predispose asthmatics to critical asthma syndromes. For many years, the contribution of vasculature to severe asthma was limited to discussion of small and medium vessel vasculitis commonly referred to as Churg-Strauss syndrome. This comprehensive review will explore the known mechanisms that are associated with remodeling of the vasculature in a variety of critical asthma presentations. Inflammation of pulmonary and bronchial small blood vessels may contribute significantly but silently to asthma pathobiology. Inflammation in the vasculature of the lung parenchyma can decrease lung capacity while inflammation in airway vasculature can decrease airflow. This review will provide a modern perspective on Churg-Strauss syndromes with a focus on phenotyping, mechanism, and ultimately modern therapeutic approaches. Vascular remodeling and airway remodeling are not mutually exclusive concepts in understanding the progression of asthma and frequency of acute exacerbations. Furthermore, the contribution of vascular leak, particularly in the parenchymal vasculature, has become an increasingly recognized component of certain presentations of poorly controlled, severe persistent asthmatic and during exacerbations. We highlight how these mechanisms can contribute to some the severe presentations of influenza infection in patients with a history of asthma. The ultimate aim of this review is to summarize the current literature concerning vasculitis and the contribution of airway and parenchymal vascular remodeling to presentation of persistent asthma and its consequences during acute exacerbations and critical asthma syndromes.