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.
Dani
Carlo
C
Department of Surgical and Medical Critical Care, Section of Neonatology, Careggi University Hospital of Florence, 50134 Florence, Italy. cddni@.unifi.it
Masini
Emanuela
E
Bertini
Giovanna
G
di Felice
Anna Maria
AM
Pezzati
Marco
M
Ciofini
Silvia
S
Rossetti
Mauro
M
Gallori
Gabriele
G
Ciuti
Riccardo
R
Buonocore
Giuseppe
G
Paffetti
Patrizia
P
Mannaioni
Pier Francesco
PF
Rubaltelli
Firmino F
FF
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