Myeloid-Derived Suppressor Cells: Possible Link Between Chronic Obstrucive Pulmonary Disease and Lung Cancer

Chronic obstructive pulmonary disease (COPD) and lung cancer (LC) are prevalent diseases and are a leading cause of morbidity and mortality worldwide. There is strong evidence to show that COPD is an independent risk factor for LC. Chronic inflammation plays a significant pathogenic role in COPD comorbidities, particularly in LC. On the one hand, cellular and molecular inflammatory mediators promote carcinogenesis and, on the other, chronic inflammation impairs the capacity of the immune system to identify and destroy pre-malignant and malignant cells, a process known as tumor immune surveillance. This altered antitumor immunity is due in part to the expansion of myeloid-derived suppressor cells (MDSC), which are characterized by an ability to suppress the antitumor activity of T-cells by down-regulation of the T-cell receptor ζ chain (TCRζ) through the catabolism of L-arginine. COPD and LC patients share a common pattern of expansion and activation of circulating MDSC associated with TCRζ downregulation and impaired peripheral T-cell function. The objectives of this study were to review the evidence on the association between COPD and LC and to analyze how MDSC accumulation may alter tumor immune surveillance in COPD, and therefore, promote LC development.