Lytic Cell Death in Chronic Lung Diseases

Regulated cell death is critical in maintaining tissue homeostasis and immune functions. The most common form of physiologic cell death is the highly precise, regulated, and relatively inflammation-free pathway of apoptosis. In contrast, necrotic or lytic cell death, which involves rapid cell lysis and release of pro-inflammatory mediators, is more often associated with human pathologies. Pyroptosis and necroptosis are two regulated forms of lytic cell death and are increasingly recognized as important mediators of tissue damage in many diseases, including lung diseases. The death of lung cells is a key contributor to disease in multiple respiratory disorders. However, current interventions are limited to targeting downstream effects to help relieve symptoms without addressing the root cause driving tissue damage. Therefore, new strategies directed towards preventing tissue damage caused by detrimental cell death are desperately needed. Emerging evidence strongly implicates regulated necrosis in many acute and chronic lung diseases, but the specific form(s) of cell death driving pathology and cell types involved require nuanced evaluation. Here, we summarize current literature suggesting that pyroptosis and necroptosis facilitate lung injury and inflammation in Chronic Obstructive Pulmonary Disease (COPD) and Idiopathic Pulmonary Fibrosis (IPF) by inducing the death of airway and alveolar epithelial cells and resident immune cells, which leads to alveolar barrier disruption, release of inflammatory mediators, excessive immune cell recruitment, and ultimate lung function decline.