title: Knockdown of lung phosphodiesterase 2A attenuates alveolar inflammation and protein leak in a two-hit mouse model of acute lung injury.
abstract: Phosphodiesterase 2A (PDE2A) is stimulated by cGMP to hydrolyze cAMP, a potent endothelial barrier-protective molecule. We previously found that lung PDE2A contributed to a mouse model of ventilator-induced lung injury (VILI). The purpose of the present study was to determine the contribution of PDE2A in a two-hit mouse model of 1-day intratracheal (IT) LPS followed by 4 h of 20 ml/kg tidal volume ventilation. Compared with IT water controls, LPS alone (3.75 μg/g body wt) increased lung PDE2A mRNA and protein expression by 6 h with a persistent increase in protein through day 4 before decreasing to control levels on days 6 and 10. Similar to the PDE2A time course, the peak in bronchoalveolar lavage (BAL) neutrophils, lactate dehydrogenase (LDH), and protein concentration also occurred on day 4 post-LPS. IT LPS (1 day) and VILI caused a threefold increase in lung PDE2A and inducible nitric oxide synthase (iNOS) and a 24-fold increase in BAL neutrophilia. Compared with a control adenovirus, PDE2A knockdown with an adenovirus expressing a short hairpin RNA administered IT 3 days before LPS/VILI effectively decreased lung PDE2A expression and significantly attenuated BAL neutrophilia, LDH, protein, and chemokine levels. PDE2A knockdown also reduced lung iNOS expression by 53%, increased lung cAMP by nearly twofold, and improved survival from 47 to 100%. We conclude that in a mouse model of LPS/VILI, a synergistic increase in lung PDE2A expression increased lung iNOS and alveolar inflammation and contributed significantly to the ensuing acute lung injury.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD 21224, USA.
authors.forename: Otgonchimeg
authors.initials: O
authors.lastname: Rentsendorj
authors.forename: Mahendra
authors.initials: M
authors.lastname: Damarla
authors.forename: Neil R
authors.initials: NR
authors.lastname: Aggarwal
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Choi
authors.forename: Laura
authors.initials: L
authors.lastname: Johnston
authors.forename: Franco R
authors.initials: FR
authors.lastname: D'Alessio
authors.forename: Michael T
authors.initials: MT
authors.lastname: Crow
authors.forename: David B
authors.initials: DB
authors.lastname: Pearse
mesh_terms: D055371:Acute Lung Injury / Q000209:etiology*; D000256:Adenoviridae / Q000201:enzymology / Q000235:genetics; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2 / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D008070:Lipopolysaccharides / Q000008:administration & dosage; D008168:Lung / Q000378:metabolism* / Q000821:virology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000473:pathology; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000378:metabolism* / Q000473:pathology*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D013990:Tidal Volume; D013997:Time Factors; D014132:Trachea; D055397:Ventilator-Induced Lung Injury / Q000378:metabolism / Q000473:pathology
chemical_list: D008070:Lipopolysaccharides; D011506:Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000242:Cyclic AMP; D052247:Nitric Oxide Synthase Type II; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; D006152:Cyclic GMP