Soluble extracellular Klotho decreases sensitivity to cigarette smoke induced cell death in human lung epithelial cells

Abstract

Chronic obstructive pulmonary disease (COPD) is currently the third leading cause of death in the US and is associated with an abnormal inflammatory response to cigarette smoke (CS). Exposure to CS induces oxidative stress and can result in cellular senescence in the lung. Cellular senescence can then lead to decreased proliferation of epithelial cells, the destruction of alveolar structure and pulmonary emphysema. The anti-aging gene, klotho, encodes a membrane bound protein that has been shown to be a key regulator of oxidative stress and cellular senescence. In this study the role of Klotho (KL) in oxidative stress and cellular senescence was investigated in human pulmonary epithelial cells exposed to cigarette smoke. Individual clones that stably overexpress Klotho were generated through retroviral transfection and geneticin selection. Klotho overexpression was confirmed through RT-qPCR, Western blotting and ELISA. Compared to control cells, constitutive Klotho overexpression resulted in decreased sensitivity to cigarette smoke induced cell death in vitro via a reduction of reactive oxygen species and a decrease in the expression of p21. Our results suggest that increasing Klotho level in pulmonary epithelial cells may be a promising strategy to reduce cellular senescence and mitigate the risk for the development of COPD.

Alpha‐Klotho, a critical protein for lung health, is not expressed in normal lung

“…There is controversy concerning whether αKlotho present in the lung is produced by resident lung cells or derived from the circulation. Several lung cell lines show αKlotho mRNA expression by RT‐PCR but none express αKlotho protein . On the other hand, Kuro‐o and colleagues discovered that αKlotho could not detect αKlotho transcript in the intact lung, a finding independently reproduced by our group .…”

“…Endogenous αKlotho transcripts have been detected in cultured lung cells transfected with αKlotho cDNA; yet none of the lung cell lines express αKlotho at baseline . Li et al performed IHC using an unspecified polyclonal anti‐αKlotho antibody, and reported co‐localization with alveolar macrophages and decreased staining in lungs of smokers and patients with chronic obstructive pulmonary disease (COPD); however, control specimens showed high background intensity, and specificity of staining was not established.…”

“…The highly enriched αKlotho content in human induced pluripotent stem cell secretome significantly contributes to protection of lung cells and lungs from hyperoxic injury . Multiple laboratories have shown direct or indirect αKlotho actions in the lung using in vitro systems . Cumulative literature unequivocally supports a pivotal cytoprotective role of αKlotho in the lung.…”

Fibroblast growth factor 23 and Klotho contribute to airway inflammation

“…It has been shown that soluble klotho has protective, anti-inflammatory effects on different cell types (25,26). To test if soluble klotho interferes with the effects of FGF23 in the lung, we co-incubated COPD-BEC with FGF23, cigarette smoke and with the ectodomain of recombinant human α-klotho at 0.1 μg/ml for 30 minutes.…”

Effects of <i>Bufei Yishen</i> formula on klotho gene expression and inflammation-related RIG-I/NF-κB pathway in cigarette smoke extract-treated BEAS-2B cells

“…It is composed of six herbs: astragalus, ginseng, rehmannia, cornus, epimedium and atractylodes, and is effective in treating patients with stable COPD. Previous studies have shown that bufei yishen is safe and effectively alleviates symptoms, and improves lung function in patients with stable COPD [15]. Some domestic scholars have found that the six herbs in the formula not only promote lung and kidney invigoration but also prevent inflammation and aging [16][17][18][19][20][21][22][23][24][25][26].…”