Paraoxonase (PON1) is principally complexed to HDL and is responsible, at least in
part, for its antioxidant properties. PON1 activity decreases in several pathologies
associated with atherosclerosis. The aim of this study was to investigate the PON1
activity and factors influencing its activity as a function of age. One hundred and
twenty nine healthy subjects aged between 22 and 89 years were recruited for the study.
We found that serum PON1 activity significantly decreased with age (r=-0.38, p<0.0001)
while its arylesterase activity as well as its concentration in the serum did not
change significantly. HDL concentrations remained unchanged with age, however, Apo
A1 concentration showed a slight negative but significant correlation with age (r=-0.19,
p<0.027). Moreover, the total cholesterol concentration was positively and significantly
correlated with age (r=0.40, p<0.001). Thus, our results suggest that the decrease
in PON1 activity cannot be explained by the decrease in Apo A1 concentrations with
age. HDL from elderly subjects was more susceptible to oxidation than HDL from young
subjects measured by higher lipid peroxidation rate. Thus, the decrease in PON1 activity
may contribute to this increased susceptibility of HDL to oxidation with aging. Altogether
our results suggest that the decrease in PON1 activity may be related to the development
of oxidative stress conditions with aging and the increased HDL susceptibility to
oxidation in elderly subjects.
