Ex vivo study on the relationship between the circadian clock of blood neutrophils and the effects of alpha1-antitrypsin therapy

Defects of alpha1-antitrypsin (AAT), a regulator of neutrophil functions, have significant implications for the development of emphysema and bronchiectasis, among others. Infusions of AAT purified from human plasma are used as therapy to increase circulating AAT levels and to reduce neutrophil activation. We hypothesize that the effect of AAT therapy is at least partially related to the neutrophil circadian clock. In this pilot study, whole blood from 6 healthy women [mean age years (SD) 29.17 (3.54)] was collected twice daily, 8 h apart. Blood was incubated alone or with 2 mg/ml AAT (Respreeza) and/or 5 µg/ml lipopolysaccharide (LPS) from <italic>Escherichia coli</italic> for 30 min. Neutrophils were isolated to examine gene expression and migration. Our data show lower expression of <italic>CD16</italic>, <italic>CXCR2</italic> and <italic>CXCR4</italic> genes in morning than in afternoon neutrophils. Neutrophils isolated in the afternoon showed higher migration compared to morning neutrophils. However, compared to morning neutrophils from untreated blood, the expression of <italic>CXCR2</italic>, <italic>SELL</italic>, <italic>CD16</italic>, <italic>CD14</italic> and <italic>CXCR4</italic> genes is higher in neutrophils from AAT-treated blood. Treatment of blood with AAT resulted in enhanced migration of morning but not afternoon neutrophils. Only <italic>CXCL8</italic> expression was strongly increased in morning and afternoon neutrophils isolated from LPS-treated blood and the addition of AAT did not reverse the effect. Overall, our data show that short exposure of the blood to exogenous AAT has an impact on the neutrophil phenotype and that this effect is related to the neutrophil circadian clock. The circadian clock of myeloid cells may influence the efficiency of augmentation therapy and needs further analysis.