Role of heme oxygenase and bilirubin in oxidative stress in preterm infants.
In a previous study, it was found that the decrease in the total plasma bilirubin level (Btot) in preterm infants was associated with the decrease in oxidative stress. We hypothesized that this occurs as a result of a pro-oxidant effect of heme oxygenase (HO), which outcompetes with the antioxidant properties of bilirubin. In this study we studied 12 preterm infants in whom the plasma levels of Btot, total hydroperoxide (TH), protein SH groups, HO activity, non-transferrin-bound iron (NTBI), and erythrocyte CuZn superoxide dismutase (CuZn SOD) activity were concurrently measured when the Btot was >220 microM and after a Btot drop of >34 microM. The Btot decrease was concurrent with the TH decrease, protein SH groups increase, and the HO and CuZn SOD activity increase and was not associated with an NTBI increase. We concluded that 1) Btot does not exert a meaningful antioxidant effect in vivo; 2) HO does not exert a pro-oxidant effect involving an NTBI increase and that, on the contrary, it could exert an antioxidant effect; and 3) the concurrent HO and CuZn SOD activity increase could indicate a synergic antioxidant effect of the two enzymes.
Department of Surgical and Medical Critical Care, Section of Neonatology, Careggi University Hospital of Florence, 50134 Florence, Italy. cddni@.unifi.it
Carlo
C
Dani
Emanuela
E
Masini
Giovanna
G
Bertini
Anna Maria
AM
di Felice
Marco
M
Pezzati
Silvia
S
Ciofini
Mauro
M
Rossetti
Gabriele
G
Gallori
Riccardo
R
Ciuti
Giuseppe
G
Buonocore
Patrizia
P
Paffetti
Pier Francesco
PF
Mannaioni
Firmino F
FF
Rubaltelli
D000975:Antioxidants / Q000378:metabolism; D001663:Bilirubin / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D006419:Heme Oxygenase (Decyclizing) / Q000097:blood*; D051547:Heme Oxygenase-1; D006801:Humans; D006861:Hydrogen Peroxide / Q000097:blood; D007231:Infant, Newborn; D007234:Infant, Premature / Q000378:metabolism*; D007501:Iron / Q000097:blood; D008297:Male; D008565:Membrane Proteins; D018384:Oxidative Stress / Q000502:physiology*; D013482:Superoxide Dismutase / Q000097:blood
D000975:Antioxidants; D008565:Membrane Proteins; D006861:Hydrogen Peroxide; D007501:Iron; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D013482:Superoxide Dismutase; D001663:Bilirubin