TGFA and chronic obstructive pulmonary disease: Despite these differences, both methods identified analytes associated with epithelial repair (HB-EGF and TGF-α) and neutrophil function (EN-RAGE, MPO and NGAL) as significant, the latter being consistent with the hypothesis that neutrophil levels are strongly associated with the development of COPD, increasing COPD severity and FEV1 decline.