Chair’s Summary: Innate and Adaptive Immune Responses in Airway Disease

The lungs are constantly exposed to the external environment, which contains myriad particles and molecules that are potentially antigenic. The respiratory immune system must maintain a state of tolerance, discriminating between potentially harmful pathogens that could promote infectious disease while ignoring innocuous particles such as dust or pollen. These immunological control systems develop during early life and are greatly influenced by genetics, infection history, age, and environmental conditions such as smoking, diet, and pollution. Asthma, emphysema, chronic obstructive pulmonary disease (COPD) and pneumonia are thought to occur as a consequence of disruption of these control systems and disturbance of respiratory tolerance. Conversely, excessive immunological tolerance may lead to ineffective clearance of infectious agents such as influenza, tuberculosis, respiratory syncytial virus, or Streptococcus pneumoniae, which in turn may lead to inflammatory lung disease, bronchitis, pneumonia, and sepsis. Respiratory diseases represent an important cause of morbidity and mortality globally, and deaths due to these diseases are increasing worldwide. Moreover, the very young and the elderly are disproportionately represented at the more severe end of the disease spectrum, with asthma being more common in children and COPD and emphysema occurring later in life. It is clear that a better understanding of the basic mechanisms underlying respiratory immune homeostasis is vital to developing novel therapeutic agents and vaccines for disease prevention and control. Traditionally, diseases have been associated specifically with either innate or adaptive immune pathways—for example, innate immunity for infections and COPD or adaptive immune systems for asthma. However, the distinction between the different arms of the immune system is becoming less apparent, and it is clear that most diseases involve contributions from both sides of the immune system. Understanding these interactions is critical in the search for more effective therapies for diseases, which are common and ever-increasing. The focus of the 29th Transatlantic Airway Conference was how innate and adaptive immune system pathways contribute to the development of a variety of lung diseases, such as asthma, COPD, and respiratory infections. The papers that the speakers presented at the meeting covered the broad areas of epithelium–immune system interactions, early effector mechanisms, the influence of the microbiome and host defense mechanisms, and immunomodulatory and regulatory pathways. The talks highlighted novel aspects of the immune system and revealed the complexity of interactions that operate within the lung.