B76-04 Alpha-1 Knockout Mice Have Increased Lung Inflammatory Cytokines That Correlate With Protease Activities

Abstract Background Alpha-1 antitrypsin deficiency (AATD) is a genetic disease characterized by progressive lung injury resulting in emphysema, respiratory failure and death for which an effective gene therapy has not yet been established despite decades of research. Alpha-1 antitrypsin (A1AT) knockout (KO) mice are known to have increased neutrophil elastase (NE). In AATD, the NE damage lung tissue that triggers an inflammatory response resulting in increased inflammatory cytokines which further recruits immune cells and amplify tissue destruction. However, cytokine profile has not been reported. Therefore, we hypothesized that AAT-KO mice would have increased neutrophil chemoattracts in their lungs regulating neutrophil influx and greater protease activity and damage. Methods Bronchoalveolar lavage (BAL) was performed in mice ages between 8-40 weeks. NE, cathepsin G (CG) and proteinase 3 (PR3) were measured by FRET in AAT-KO mice and compared with age-matched WT controls. Cytokines in BAL measured by Luminex, and complete blood count from the plasma analyzed by Hemavet. Results We observed that AAT-KO mice exhibited markedly elevated protease activities, including NE, PR3 and CG, in BAL from 4 to 40 weeks of age and compared with age-matched WT mice (p 0.05). We further show that AAT-KO mice display elevated proinflammatory cytokine levels in BAL including IL-8 homologues (CXCL-1, 2 and 5), IL-1α, IL-1β, and GM-CSF, at 8 and 24 weeks of age compared with WT controls. NE, PR3 and CG showed a positive correlation with the cytokine levels of CXCL-1, CXCL-2, CXCL-5, IL-1α, IL-1β and GM-CS in the BAL. In addition, we observed twofold increase in the peripheral blood counts of neutrophils, lymphocytes, and white blood cells in A1AT KO mice. These results suggest that increased lung proinflammatory cytokines correlate with NE and CG levels. Conclusions Taken together our data suggest that loss of A1AT in AAT-KO mice results in increased lung inflammation and similar cytokine profiles to that seen in humans with AATD. The A1AT knockout mouse provides an important model for investigating underlying mechanisms of protease-driven inflammation. This abstract is funded by: NIH NHLBI 1R01HL170156-01A1, NIH NCATS 2UL1TR001425, UC IM Impact Grant