Constitutive transgenic α-Klotho overexpression enhances resilience to and recovery from murine acute lung injury

• Published in: American journal of physiology. Lung cellular and molecular physiology 2021-10, Vol.321 (4), p.L736-L749
• Main Authors: Gagan, Joshuah M, Cao, Khoa, Zhang, Yu-An, Zhang, Jianning, Davidson, Taylor L, Pastor, Johanne V, Moe, Orson W, Hsia, Connie C W
• Format: Article
• Language: English
• Subjects: Acute Lung Injury - pathology; Acute Lung Injury - prevention & control; Animals; Cell Line; Cytoprotection - genetics; Cytoprotection - physiology; DNA Breaks, Double-Stranded; DNA Damage - genetics; Female; Glucuronidase - blood; Glucuronidase - genetics; Glucuronidase - metabolism; HEK293 Cells; Humans; Hyperoxia; Klotho Proteins; L-Lactate Dehydrogenase - analysis; Lung - metabolism; Male; Mice; Mice, Transgenic; Smoke - adverse effects
• ISSN: 1040-0605; 1522-1504
• DOI: 10.1152/ajplung.00629.2020

Normal lungs do not express α-Klotho (Klotho) protein but derive cytoprotection from circulating soluble Klotho. It is unclear whether chronic supranormal Klotho levels confer additional benefit. To address this, we tested the age-related effects of modest Klotho overexpression on acute lung injury (ALI) and recovery. Transgenic Klotho-overexpressing ( ) and wild-type ( ) mice (2 and 6 mo old) were exposed to hyperoxia (95% O ; 72 h; injury; Hx) then returned to normoxia (21% O ; 24 h; recovery; Hx-R). Control mice were kept in normoxia. Renal and serum Klotho, lung histology, and bronchoalveolar lavage fluid oxidative damage markers were assessed. Effects of hyperoxia on Klotho release were tested in human embryonic kidney cells stably expressing Klotho. A549 lung epithelial cells transfected with cDNA or vector were exposed to cigarette smoke; lactate dehydrogenase and double-strand DNA breaks were measured. Serum Klotho decreased with age. Hyperoxia suppressed renal Klotho at both ages and serum Klotho at 2 mo of age. mice at both ages and 2-mo-old mice survived Hx-R; 6-mo-old mice showed lower lung damage than age-matched mice. Hyperoxia directly inhibited Klotho expression and release in vitro; transfection attenuated cigarette smoke-induced cytotoxicity and DNA double-strand breaks in lung epithelial cells. Young animals with chronic high baseline Klotho expression were more resistant to ALI. Chronic constitutive Klotho overexpression in older animals attenuated hyperoxia-induced lung damage and improves survival and short-term recovery despite an acute reduction in serum Klotho during injury. We conclude that chronic enhancement of Klotho expression increases resilience to ALI.