JCI - Exogenous administration of heme oxygenase-1 by gene transfer provides protection against hyperoxia-induced lung injury

Exogenous administration of heme oxygenase-1 by gene transfer provides protection against hyperoxia-induced lung injury

Leo E. Otterbein, Jay K. Kolls, Lin L. Mantell, Julia L. Cook, Jawed Alam, Augustine M.K. Choi

J Clin Invest. 1999; 103(7):1047–1054 doi:10.1172/JCI5342

Abstract | Full text | PDF

H eme oxygenase-1 (HO-1) confers protection against a variety of oxidant-induced cell and tissue injury. In this study, we examined whether exogenous administration of HO-1 by gene transfer could also confer protection. We first demonstrated the feasibility of overexpressing HO-1 in the lung by gene transfer. A fragment of the rat HO-1 cDNA clone containing the entire coding region was cloned into plasmid pAC-CMVpLpA, and recombinant adenoviruses containing the rat HO-1 cDNA fragment Ad5-HO-1 were generated by homologous recombination. Intratracheal administration of Ad5-HO-1 resulted in a time-dependent increase in expression of HO-1 mRNA and protein in the rat lungs. Increased HO-1 protein expression was detected diffusely in the bronchiolar epithelium of rats receiving Ad5-HO-1, as assessed by immunohistochemical studies. We then examined whether ectopic expression of HO-1 could confer protection against hyperoxia-induced lung injury. Rats receiving Ad5-HO-1, but not AdV-βGal, a recombinant adenovirus expressing Escherichia coli β-galactosidase, before exposure to hyperoxia (>99% O₂) exhibited marked reduction in lung injury, as assessed by volume of pleural effusion and histological analyses (significant reduction of edema, hemorrhage, and inflammation). In addition, rats receiving Ad5-HO-1 also exhibited increased survivability against hyperoxic stress when compared with rats receiving AdV-βGal. Expression of the antioxidant enzymes manganese superoxide dismutase (Mn-SOD) and copper-zinc superoxide dismutase (CuZn-SOD) and of L-ferritin and H-ferritin was not affected by Ad5-HO-1 administration. Furthermore, rats treated with Ad5-HO-1 exhibited attenuation of hyperoxia-induced neutrophil inflammation and apoptosis. Taken together, these data suggest the feasibility of high-level HO-1 expression in the rat lung by gene delivery. To our knowledge, we have demonstrated for the first time that HO-1 can provide protection against hyperoxia-induced lung injury in vivo by modulation of neutrophil inflammation and lung apoptosis.

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Figure 1

Kinetics of HO-1 mRNA expression in rat lungs after Ad5-HO-1 administration. Total RNA was extracted from lung tissue after Ad5-HO-1 administration and analyzed for HO-1 mRNA expression by Northern blot analysis at the indicated times. (a) Lane 1: vehicle control 72 h; lane 2: vehicle control 72 h; lane 3: 6 h; lane 4: 24 h; lane 5: 48 h; lane 6: 72 h; lane 7: 1 week; lane 8: 2 weeks; lane 9: 2 weeks. (b) Ethidium bromide staining of the same RNA is shown for loading control. HO-1, heme oxygenase-1.