Abstract Background Exacerbations of chronic obstructive pulmonary disease (COPD) are often triggered by viral infections, including influenza A virus (IAV), and accelerate disease progression, hospitalization, and mortality. There is a critical need for in vivo models that replicate viral-induced COPD exacerbations and allow mechanistic investigation. Our single-cell RNA sequencing analysis of COPD lungs, together with analysis of the Lung Genomics Research Consortium (LGRC) and the Lung Tissue Research Consortium (LTRC) cohort, revealed that QKI (quaking homolog, KH domain RNA binding protein) expression is reduced in alveolar type 2 epithelial cells (AT2 cells) and whole lung tissue in COPD, with confirmation at the protein level - suggesting a pathogenic role for QKI loss in COPD. Objective To investigate the role of QKI in influenza-induced COPD exacerbation using in vivo and in vitro models. Materials and Methods We generated a QKI KO BEAS-2B lung epithelial cell line, using a CRISPR/Cas9 system, and QKI-restored cells via lentiviral re-expression. Clonogenic capacity, cell apoptosis, and mitochondrial function were assessed, along with protein expression of peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α), a master regulator of mitochondrial biogenesis. To evaluate QKI function in vivo, AT2 cell-specific QKI KO mice with a triple-transgenic model of Sftpctm1(cre/ERT2)Blh/ROSA26mTmg/Qkiflox/flox (QKI KO) and Sftpctm1(cre/ERT2)Blh/ ROSA26mTmg/Qki+/+ mice (control). At 8 weeks of age, mice received tamoxifen to induce QKI depletion. Three weeks later, KO and control mice were infected intranasally with 10 pfu of IAV (A/Puerto Rico/8/1934(H1N1)). Body weight and pulmonary function were monitored. Lungs were harvested on day 28 post-infection for histology and protein analyses. Results QKI KO BEAS-2B cells exhibited reduced colony formation and increased apoptosis, accompanied by a metabolic shift toward glycolysis, elevated electron transport chain leakage, and oxidative stress. QKI restoration partially reversed these phenotypes. PGC-1α protein levels were reduced in QKI KO cells relative to control cells. In vivo, IAV-infected KO mice showed greater weight loss, enhanced lung inflammation, reduced static lung compliance, and increased αSMA protein levels, as well as enhanced collagen deposition compared with controls. Conclusions QKI loss in lung epithelial cell lines impairs epithelial cell proliferation and disrupts mitochondrial function, and increases susceptibility to IAV-induced lung injury. These findings suggest that AT2-specific QKI deficiency exacerbates IAV-induced lung inflammation and fibrosis. These models recapitulate key features of viral COPD exacerbation and suggest that QKI-loss-driven mitochondrial dysfunction compromises epithelial homeostasis and repair, contributing to both COPD pathogenesis and its exacerbations. This abstract is funded by: American Heart Association Postdoctoral Fellowship program (24POST1193659) and VA merit review grant (BX006096)
Miyamoto et al. (Fri,) studied this question.