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 10

Effect of Ad5-HO-1 on hyperoxia-induced apoptosis in the rat lung. Lung sections from rats were analyzed for apoptotic signals by TUNEL-positive cells and costained with DAPI to determine the apoptotic index (number of TUNEL-positive cells per number of DAPI-stained cells) after 56 h of hyperoxia exposure. Bar 1: normoxia controls; bar 2: hyperoxia alone 56 h; bar 3: hyperoxia Ad5-HO-1 56 h; bar 4: Ad5-HO-1 alone 56 h; bar 5: AdV-βGal alone 56 h. Data represent the mean value ± SE of three rats. *P < 0.05 compared with normoxia controls. **P < 0.001 compared with hyperoxia alone. DAPI, 4′6-diamidine-2-phenylindole-dihydrocholride; TUNEL, terminal deoxynucleotide transferase–mediated dUTP nick end-labeling.