Editorial: Developing Better Biomarkers for Connective Tissue Disease–Associated Interstitial Lung Disease: Citrullinated Hsp90 Autoantibodies in Rheumatoid Arthritis

Interstitial lung disease (ILD) describes a heterogeneous group of parenchymal pulmonary conditions that sometimes defy easy categorization (1). This frequently lethal collection of disorders is often characterized by signs and symptoms of systemic inflammation, findings that suggest that immunity causes or, at least, contributes to the development of pulmonary disease. Because lungs interface constantly with the outside world, it is not surprising that the barrier function of the airways requires not only constant mechanical removal of foreign antigens (e.g., cough reflexes, a mucociliary elevator) but also an actively engaged and sophisticated set of immune defenses.