55 of the PON1 gene. The PCR products were digested with NlaIII and electrophoresed in 2% agarose gels. Genotypes at both loci were confirmed by direct sequencing of amplified DNA fragments with an automatic sequencer. The variability of the PON1 gene at codons 192 (Gln/Arg=A/B alleles) and 55 (Leu/Meth=L/M alleles) has been associated with enzymatic activity and concentration. Consistently, a large number of studies suggest an association between cardiovascular diseases and the Arg variant. Even Leu 192 55 has been associated with cardiovascular disease susceptibility. Interestingly, recent data indicate that PON1 genotype affects the vasculature responsiveness to triglycerides.

In this study, we tested the hypothesis that PON1 genotypes affect long-term survival, i.e., whether allele, genotype, and combined genotypes frequency distributions of centenarians are different from those found in young individuals. We examined these two amino acid changes in 579 people aged 20 to 65 years old and 308 centenarians. We found that the percentage of carriers of the B allele at codon 192 (B+ individuals) is higher in centenarians than in controls (0.539 vs 0.447). Moreover, we found that among the B+ individuals, the phenomenon was due to an increase of people carrying M alleles at codon 55 locus.

No significant difference was present between Northern and Southern Italians either in centenarians or in controls. In both age classes, the observed genotypes were in agreement with those expected at Hardy-Weinberg Equilibrium. Significant differences between young people and centenarians were evident when allele and genotype frequency distributions were compared. In particular, the proportion of B+ subjects (AB+BB individuals) was increased in centenarians in comparison to young people. The role of gender as a confounding variable was tested, and no significant result was found. 

Serum Paraoxonase 1 (PON1) has been claimed to play a central role in the scenario. The enzyme is a High Density Lipoprotein (HDL)-bound Arylesterase which hydrolyzes lipid peroxides and is therefore responsible for the protective effects of HDL on peroxidation of Low Density Lipoproteins (LDL). Indeed, oxidized LDL is capable of stimulating the production of foam cells, is cytotoxic towards arterial wall cells, and induces macrophagic cytokines, resulting in highly proinflammatory and proatherogenic. The inter-individual variability of PON1 serum activity has been thought to modulate the risk to develop atherogenesis. In fact, the lipo-peroxides. PON1 has recently attracted attention as a protective factor against oxidative modification of LDL and may therefore play an important role in the prevention of the atherosclerotic process. Two polymorphisms have been extensively studied: a Leucine (L allele) to Methionine (M allele) substitution at codon 55 and a Glutamine (A allele) to Arginine (B allele) substitution at codon 192.

A great deal of data indicates that risk factors for the major causes of mortality in the elderly (cardiovascular diseases, diabetes) are associated with alterations in antioxidant, inflammatory, and lipidic profile. Particular importance has been attributed to the role of peroxidation of LDL in atherogenesis and to the capability of proteins of modulating local inflammatory response. The first two authors contributed equally to this study.effects of oxidative stress, thus delaying the onset of age-related diseases. Our findings are consistent with previous studies that have suggested a protective role of the B allele in cardiovascular diseases and other age-related pathologies.

The observed differences in haplotype frequency between young people and centenarians suggest that the combination of PON1 variants may also play a role in longevity. The increase in BM haplotype frequency among centenarians further supports this hypothesis. However, it should be noted that the estimation of haplotype frequencies is sensitive to population stratification, and our analysis was limited to the Italian population. Further studies in larger and more diverse populations are needed to confirm our findings.

In conclusion, our study provides evidence for an association between PON1 genetic variability and longevity in the Italian population. Carriers of the B allele and B+M+ genotype combination appear to be protected against age-related diseases and may have an enhanced capacity to counteract oxidative stress. These findings contribute to our understanding of the genetic factors underlying longevity and may have implications for the development of strategies to promote healthy ageing.Effects of the accumulation of pro-inflammatory molecules and the increase of the pro-inflammatory status that accompany human aging. Functional studies of the correlation between PON1 genotype and PON1 activity in cells from centenarians may clarify this point. The observed gene/longevity association is not highly significant. This finding implies that the effect of PON1 variability on the overall population mortality is rather slight, and this finding is in line with the results obtained in several gene/longevity association studies. Moreover, the AB heterozygous 192 genotype appears to contribute rather largely to the observed association (Table 1). A recently developed mathematical model explains the variation of heterozygosity in an ageing cohort in terms of differential survival as affected by the biological role of the gene. According to the model, centenarians are expected to show increasing heterozygosity with respect to young subjects for stress-responder genes driving individual adaptive capacity. Data in Table 1 suggest that PON1 is one of the genes affecting such adaptive capability, and therefore one of the genes affecting rate and quality of aging.