LEP and chronic obstructive pulmonary disease: Five proteinswith known lung injury or acute COVID-19 injury mechanismswere significantly associated with DLCO, %, in post-COVID-19 conditions.Adiponectin (ADIPOQ), an adipose tissue-derived protein hormone, regulatesglucose and fatty acid oxidation; low adiponectin to leptin levelsoccur in acute COVID-19 pneumonia87 andmay be important in post-COVID-19 condition restrictive lung disease.α-Antitrypsin (SERPINA1) is a protease inhibitor that protectsagainst COPD emphysema; α-antitrypsin deficiency causes emphysema,by protecting against neutrophil elastase-induced lung injury.