Paraoxonase and platelet-activating factor acetylhydrolase activities in lipoproteins of beta-thalassemia/hemoglobin E patients.
BACKGROUND
Iron-induced oxidative stress may be implicated in the alteration of the lipoprotein-associated antioxidant enzymes paraoxonase 1 (PON1) and platelet-activating factor acetylhydrolase (PAF-AH), leading to atherosclerosis-related vascular complication in patients with beta-thalassemia hemoglobin E (beta-thal/Hb E).


METHODS
Plasma and lipoprotein enzyme activities of PON1 and PAF-AH were studied in 13 mild to moderate and 15 severe cases of beta-thal/Hb E in comparison with 15 normal subjects.


RESULTS
PON1 activity was significantly reduced in association with oxidative stress in the patients. There were significant correlations between high-density lipoprotein (HDL)-PON1 activity and oxidative stress markers, including plasma levels of alpha-tocopherol (r=0.694 p<0.001) and the ratio of cholesteryl linoleate to cholesteryl oleate (CL/CO, r=0.662, p<0.001) in HDL. On the other hand, PAF-AH activity was markedly increased in patients by approximately two-fold and three- to four-fold in plasma and lipoproteins, respectively. Significant correlations of low-density lipoprotein (LDL) and HDL-PAF-AH activity with plasma iron, alpha-tocopherol and the CL/CO ratio were also demonstrated.


CONCLUSIONS
We suggest that impairment of PON1 activity may be directly caused by oxidative damage, while increased PAF-AH activity possibly results from oxidative stress-induced inflammatory response in beta-thal/Hb E patients.
Phumala Morales
Noppawan
N
Department of Pharmacology, Faculty of Science, Mahidol University, Bangkok, Thailand.
Cherlermchoung
Chalermkhwan
C
Fucharoen
Suthat
S
Chantharaksri
Udom
U
D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D043303:Aryldialkylphosphatase / Q000097:blood / Q000378:metabolism*; D008078:Cholesterol, LDL / Q000097:blood; D005260:Female; D006446:Hemoglobin E; D006801:Humans; D008074:Lipoproteins / Q000097:blood / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000097:blood; D008297:Male; D018384:Oxidative Stress; D017086:beta-Thalassemia / Q000201:enzymology*
D008078:Cholesterol, LDL; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D006446:Hemoglobin E; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D043303:Aryldialkylphosphatase