Pulmonary gain-of-function toxicity in alpha-1 antitrypsin deficiency
Overall, we found that AAT is expressed in alveolar type 2 cells in addition to alveolar macrophages in primary human lung tissue. AT2s and alveolar macrophages in ZZ-AATD exhibit a distinct transcriptomic signature including inflammatory pathway and unfolded protein response gene set enrichment. AT2s in ZZ-AATD additionally exhibit evidence of cell stress including ATF4 regulon enrichment and expression of cleaved caspase 3. Together, these findings extend the prevailing paradigm of emphysema pathogenesis in ZZ-AATD and suggest AAT-expressing resident lung cells as logical therapeutic targets for future study. Overall design: Survey of human adult lung from AATD diseased  tissue using single cell RNA sequencing.