Assessment of Inflammation in COPD: Are There any Biomarkers that Can be Used to Assess Pulmonary and Systemic Inflammation?

Abstract

Numerous inflammatory substances have been identified as potentially useful biomarkers to evaluate COPD. These substances were derived from sputum, blood, exhaled gas, exhaled breath condensate, and bronchoscopic specimens. However, the majority of these biomarkers are not currently clinically applicable due to the lack of sufficient difference of value between COPD subjects and healthy subjects, insufficient validation in randomized controlled trial, invasive procedure required to obtain specimen directly from the lung, or technical issue preventing reproducible measurements. Nonetheless, we have biomarkers that can be used to assess pulmonary and systemic inflammation for patients with COPD. Plasma fibrinogen can predict the future incidence of COPD and future FEV1 decline in COPD and non-COPD subjects. In July 2015, the US Food and Drug Administration approved serum fibrinogen as the first COPD biomarker to identify patients that are at a higher risk of exacerbation or death in clinical trials. Researchers hope this approval will accelerate trials for new medications. Serum C-reactive protein is another widely approved biomarker related to COPD diagnosis, exacerbation diagnosis, and patient prognosis. Sputum/ blood eosinophils, fractional exhaled nitric oxide, and the T helper type 2 genes can be candidate predictive biomarkers to pick up the asthma-COPD overlap syndrome cases who are amenable to inhaled corticosteroids. The tumor necrosis factor-a-308 variant is associated with COPD risk and emphysematous change especially in Asians.