Additionally, previous studies have demonstrated that COPD exacerbations are mainly associated with aggravated airway inflammation, such as increased numbers of inflammatory cells, including WBCs and neutrophils, and increased levels of acute inflammatory biomarkers, including IL-1β, IL-6, TNF-α, IL-10, CRP, and SAA [8, 11, 33–36]. Here, TNF is linked to chronic obstructive pulmonary disease.