Pulmonary expression of inducible heme-oxygenase after ischemia/reperfusion of the lower extremities in rats.
BACKGROUND
Expression of inducible heme-oxygenase (HO-1) has been shown to be increased in various inflammatory disorders, which may confer a protective role. The aim of our study was to assess pulmonary expression of HO-1 after ischemia/reperfusion (I/R) of the lower limbs in rats.


METHODS
We compared three groups of rats (n = 5/group): one Sham group, and two I/R groups (aorta cross-clamped for 2 h followed by 2 h of reperfusion), one of which pre-treated with Zn-protoporphyrin (Zn-PP), a competitive inhibitor of HO (50 micromol/kg, i.p.). At the end of experiment, lungs were harvested for determination of HO activity and HO-1 expression by Western blot and immunohistochemistry. Lung injury was assessed by bronchoalveolar lavage, histological study, and determination of the lung Evans Blue dye content, an index of microvascular permeability.


RESULTS
I/R of the lower limbs was responsible for acute lung injury (ALI), characterized by neutrophilic infiltration (87 +/- 20 x 10(3) neutrophils/mm(3), Sham group versus 191 +/- 38 x 10(3) neutrophils/mm(3), I/R group; P < 0.002) and an increase in lung Evans blue dye content: (74 +/- 6 microg/g, Sham group versus 122 +/- 48 microg/g, I/R group; P < 0.05). Pre-treatment with Zn-PP further increases the Evans Blue content (122 +/- 48 microg/g, I/R group versus 179 +/- 23 microg/g Zn-PP group P < 0.05) and the neutrophilic infiltration. Pulmonary heme-oxygenase activity, and HO-1 content were increased after I/R. (10.5 +/- 12 pmol bilirubin/mg protein/h, Sham group versus 101.2 +/- 66 pmol bilirubin/mg protein/h, I/R group; P < 0.02). Immunohistochemistry revealed that the expression of HO-1 was mainly localized to inflammatory cells.


CONCLUSIONS
ALI following I/R of the lower limbs in rats is associated with an increase of pulmonary expression of HO-1, inhibition of this expression increase the severity of ALI.
Boutros
Cherif N
CN
Laboratory of the Study of Cardiac Grafts and Prostheses, Broussais Hospital, Paris, France. cherifboutros@hotmail.com
Zegdi
Rachid
R
Lila
Nermine
N
Combillau
Michele
M
Fornes
Paul
P
Carpentier
Alain
A
Noel Fabiani
Jean
J
D000818:Animals; D001012:Aorta, Abdominal; D004396:Coloring Agents / Q000493:pharmacokinetics; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005070:Evans Blue / Q000493:pharmacokinetics; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006614:Hindlimb / Q000098:blood supply*; D008168:Lung / Q000201:enzymology* / Q000473:pathology; D008297:Male; D011524:Protoporphyrins / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000150:complications / Q000378:metabolism*; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D012720:Severity of Illness Index
D004396:Coloring Agents; D004791:Enzyme Inhibitors; D011524:Protoporphyrins; C017803:zinc protoporphyrin; D005070:Evans Blue; D051547:Heme Oxygenase-1