4. Discussion

The results of the present study indicate that HP 1/2 polymor- affects the probability of reaching extreme old age, by acting early in adult life (Comparison 1). To our knowledge, this is first report relating the HP genetic polymorphisms and human in a large group of elderly individuals. However, previous examined the age-distribution of HP 1/2 polymorphism in subjects from three other populations, Chinese Fujian Han Jordanians [13] and Polish [14], respectively, very distinct for

In our study, the frequencies of HP*1/*1 genotype and HP*1 allele were found to be significantly higher in the elderly groups than in younger group, suggesting that possessing this genotype could confer a survival advantage for attaining longevity. Furthermore, this evidence is sustained by the above mentioned studies, reporting significant age-dependent increase of HP*1 allele, with Polish study evidencing a considerable increase of HP*1/*1 genotype in subjects aged 81–91 years [14]. On the other side, both HP*2/*1 and HP*2/*2 carriers display a significant deleterious effect compared to HP*1/*1 homozygous.

Table 1

HP1/2polymorphism: genotype andallele frequenciesinageclassesstudied.Valuesshowingsignificantdifferencesareshowninbold.O.R.=oddsratio.*AssumingHP*2astherisk allele.

HP Groups Age Class 1 Age Class 2 Age Class 3 Males (b66 y, N=144) Males (66–88 y, N=261) Males (N88 y, N=98) Females (b73 y, N=190) Females (73–91 y, N=286) Females (N91 y, N=93) Total N=334 Total N=547 Total N=191 1*/1* 37 (11.1%) 96 (17.6%) 33 (17.3%) 2*/1* 145 (43.4%) 227 (41.5%) 80 (41.9%) 2*/2* 152 (45.5%) 224 (40.9%) 78 (40.8%) 1* 219 (32.8%) 419 (38.3%) 146 (38.2%) 2* 449 (67.2%) 675 (61.7%) 236 (61.8%) Tests for association (C.I.: 95% confidence interval)* Comparison 1: Age Class 2 vs. Age Class 1 Allele freq. difference Heterozygous Homozygous Allele positivity Armitage's trend test [1*]↔[2*] [1*/1*]↔[2*/1*] [1*/1*]↔[2*/2*] [1*/1*]↔[2*/1*+2*/2*] Common odds ratio O.R.=0.786 O.R.=0.603 O.R.=0.568 O.R.=0.585 O.R.=0.782 C.I.=[0.642–0.962] C.I.=[0.391–0.930] C.I.=[0.369–0.875] C.I.=[0.390–0.879] χ2=5.03 χ2=5.46 χ2=5.29 χ2=6.69 χ2=6.78 p=0.02492 p=0.01943 p=0.02142 p=0.00971 p=0.00923 Comparison 2: Age Class 3 vs. Age Class 2 Allele freq. difference Heterozygous Homozygous Allele positivity Armitage's trend test [1*]↔[2*] [1*/1*]↔[2*/1*] [1*/1*]↔[2*/2*] [1*/1*]↔[2*/1*+2*/2*] Common odds ratio O.R.=1.003 O.R.=1.025 O.R.=1.013 O.R.=1.019 O.R.=1.005 C.I.=[0.790–1.275] C.I.=[0.640–1.641] C.I.=[0.632–1.624] C.I.=[0.660–1.575] χ2=0.00 χ2=0.00 χ2=0.01 χ2=0.00 χ2=0.01 p=0.97914 p=0.97793 p=0.91733 p=0.95727 p=0.93190

Tests for association (C.I.: 95% confidence interval)*

also shown that binding of CD163 to HP*2–Hb complexes lowers significantly the amount of released anti-inflammatory IL-10 [20].

AlthoughtheHP*1allelefrequencyofAgeClass1islower(0.33)than the ones published for Italian population (Rome: 0.36 [10], Sicily: 0.42 [10]; North West Italy: 0.37 [15]), the population of Marche region is genetically similar to South eastern European populations [16], making theresultsreportedheregeneticallyplausible.Moreover,astudycarried outonthepopulationoftheMiddleSangroValley(Abruzzoregion,Italy, 430 individuals, 15–88 years) [17], located on the eastern side of ApennineandborderingtheMarcheregiontothenorth,reportsanHP*1 frequency of 0.34, very similar to that reported for Age Class 1.

DNA damage and mutations have also been implicated as key causal events in the process of aging [21]. In this context oxidative damage to DNA induced by hydrogen peroxide may be prevented by HP, as demonstrated by a recent finding that HP*1/*1 genotype was associated with a lower rate of DNA damage [22]. Our results are also sustained by numerous studies reporting the association of HP*2/*1 and HP*2/*2 genotypes with several age-related diseases such as abdominal aortic aneurysm [23], atherosclerosis [24,25], type 2 diabetes [26], hypertension [27] and Parkinson's disease [28].

HP 1/2 polymorphism is characterized by the production of three distinct biochemical phenotypes, each one possessing different molec- ular configurations and functions. In this model the small HP 1-1 molecule has theadvantage byits higher Hb-bindingcapacity and byits distribution in the extravascular fluid and in the liver, while the larger HP 2-1 molecule has the drawback of its lower Hb-binding capacity and by its distribution in the extravascular fluid, and the HP 2-2 molecule is moderately favored by a balance between low level of HP 2-2-Hb complex elimination via CD163 [18] and the efficiency by which the HP cyclic polymer is eliminated via the extravascular fluid and the liver [5]. Moreover HP 2-2 has been associated with a significant decrease of receptor CD163 expression [18]. Thus, due to their higher levels of free Hb, the tissues of HP*2/*2 subjects might contain higher levels of reactive oxygen species and could be more exposed to oxidative damage. The macrophage CD163 receptor functions not only as a scavenger for HP–Hb complexes, but may also have an immune modulatory action with pivotal anti-inflammatory properties which entails IL-10, heme oxygenase and bilirubin synthesis [19]. It has been

Thus, most of the accumulated evidence supports a potential role of HP in human health, aging and longevity. Furthermore, in light of its association with various aging phenotypes, and of its documented interactionwith another “longevitygenes”(i.e.APOA1, APOB, APOE, HFE, HMOX1,IL-6,IL-10andTNF-α)[29–35],theHPgenecanberegardedasa potential fork-head or bridge between immuno-aging, free radicals and human aging/longevity (http://genomics.senescence.info/genes/