Klotho Regulates Club Cell Senescence and Differentiation in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is characterised by chronic inflammation and senescence. Previous studies showed that club cells and club cell secretory proteins (CCSP) have anti-inflammatory roles, which reduced in COPD. Klotho (KL) decreased in human COPD lung tissue. KL-deficient mice showed aging phenotypes, such as obvious emphysema and premature senility at the early stage, which are characteristics of COPD. However, little is known about the relationship between KL, club cells, and COPD. We speculated lack of KL would aggravate club cell senescence, which contributes to COPD inflammation. We collected COPD lung tissue using single-cell RNA sequencing (scRNA-seq), revealing club cells heterogeneity and cellular senescence in COPD. In addition, KL and CCSP expressions were downregulated in cigarette smoke (CS)-induced COPD mice, associated with increasing age-related markers. After KL knockout, more ciliated cells appeared where club cells disappeared. Furthermore, KL deficiency aggravated club cell senescence and CSE-induced pulmonary inflammation. To investigate the specific regulation mechanism, hnRNPA2/B1 was recognised and identified it was the key molecule in KL-regulated club cell senescence, and neddylation of club cell was a crucial factor contributing to hnRNPA2/B1 downregulation. In vitro, SA-β-gal staining suggested the aging phenotype was aggravated in hnRNPA2/B1-silenced groups, and hnRNPA2/B1 over-expressed achieved a rescue result. Thus, KL could regulate club cell senescence and differentiation. When CS stimulates the small airway epithelium, KL deficiency aggravates lung inflammation, club cell senescence and dysfunctional of ciliated cell. Targeting neddylation might be a promising strategy to reverse lung aging and club cell senescence. These results provide a mechanism about COPD-linked lung inflammation.