CRP and chronic obstructive pulmonary disease: Kunisaki et al. have recently shown that in ex-smokers with severe COPD, FENO, may be more closely associated with FEV1 responses to four weeks of ICS than are standard markers of systemic inflammation namely serum c-reactive protein (CRP), IL-6, and IL-8.[79] FENO may have a role in the monitoring of anti-inflammatory therapy of COPD and can be used to identify patients who may respond to steroids.