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To investigate the genetic contribution to familial similarity in longevity, we set up a novel experimental design where cousin-pairs born from siblings who were concordant or discordant for the longevity trait were analyzed. To check this design, two chromosomal regions already known to encompass longevity-related genes were examined: 6p21.3 (genes TNFalpha, TNFbeta, HSP70.1) and 11p15.5 (genes SIRT3, HRAS1, IGF2, INS, TH). Population pools of 1.6, 2.3 and 2.0 million inhabitants were screened, respectively, in Denmark, France and Italy to identify families matching the design requirements. A total of 234 trios composed by one centenarian, his/her child and a child of his/her concordant or discordant sib were collected. By using population-specific allele frequencies, we reconstructed haplotype phase and estimated the likelihood of Identical By Descent (IBD) haplotype sharing in cousin-pairs born from concordant and discordant siblings. In addition, we analyzed haplotype transmission from centenarians to offspring, and a statistically significant Transmission Ratio Distortion (TRD) was observed for both chromosomal regions in the discordant families (P=0.007 for 6p21.3 and P=0.015 for 11p15.5). In concordant families, a marginally significant TRD was observed at 6p21.3 only (P=0.06). Although no significant difference emerged between the two groups of cousin-pairs, our study gave new insights on the hindrances to recruiting a suitable sample to obtain significant IBD data on longevity-related chromosomal regions. This will allow to dimension future sampling campaigns to study-genetic basis of human longevity.

Sequence variations in a variety of pro- or anti-inflammatory cytokine genes have been found to influence successful aging and longevity. Because of the role played by the transforming growth factor beta1 (TGF-beta1) cytokine in inflammation and regulation of immune responses, the variability of the TGF-beta1 gene may affect longevity by playing a role in inflamm-aging. Two polymorphisms, G/A -800 and C/T -509, located in the 5' region, and two missense polymorphisms, T/C 869 and G/C 915 which change (Leu > Pro)10 and (Arg > Pro)25, respectively, located in the signal peptide, were analysed in 419 subjects from Northern and Central Italy, including 172 centenarians and 247 younger controls. In addition, the effects of the TGF-beta1 genetic variability on plasma levels of the biologically active form (naturally processed) of this cytokine were studied in 143 randomly selected subjects, including 73 centenarians. Significant differences were found at the +915 site as far as the C allele and GC genotype were concerned, both of them being lower in centenarians than in young controls (P=0.034 and 0.028, respectively), but none of the other tested genetic variants was significantly different between centenarians and controls. Moreover, a particular haplotype combination (G -800/C -509/C 869/C 915) was notably lower in centenarians than in younger individuals (P=0.007). Finally, active TGF-beta1 plasma levels were significantly increased in the elderly group, but no relationship with TGF-beta1 genotypes was observed. These results suggest that, at least in this population, the variability of the TGF-beta1 gene influences longevity and that the age-related increase in plasma levels of active TGF-beta1 seems not to be genetically regulated.

Two different polymorphic regions of the interleukin-6 (IL-6) gene were investigated in patients with Alzheimer's disease (AD) and non-demented controls. The -174 C allele in the promoter region of IL-6 gene was over-represented in AD patients compared to controls and significantly increased the risk of AD. Moreover, the -174 CC genotype was associated with a high risk of the disease in women. The D allele of a variable number of tandem repeat (VNTR) was in strong linkage disequilibrium with the -174 C allele and slightly increased AD risk. On the other hand, the frequency of the VNTR C allele was decreased in patients with AD and was negatively associated with the risk of developing AD. Both the -174 CC and VNTR DD genotypes were also associated with increased IL-6 levels in the blood and brain from AD. These findings suggest that IL-6 may play a multifaceted role in AD by affecting the turnover of the cytokine.

In this study, we analysed the polymorphic variants of IL-1alpha (C-T transition at position -889), IL-1beta (C-T transition at position -511) and IL-1 receptor antagonist (Ra) (86-bp repeated sequence in intron 2) in 1131 subjects (453 females and 678 males) from Northern and Central Italy, including 134 centenarians, to evaluate whether IL-1 cluster alleles might be differently represented in people selected for longevity. In addition, IL-1Ra and IL-1beta plasma levels were quantified by ELISA in 130 randomly selected subjects. No significant differences in the genotype and allele frequency distributions were observed between young, elderly and centenarian subjects. IL-1Ra plasma levels showed an age-related increase, whereas IL-1beta plasma levels did not show any detectable age-related trend. Neither IL-1Ra nor IL-1beta plasma levels showed any relationship with genotypes of the three IL-1 genes. These results suggest that no one particular polymorphism in the IL-1 gene cluster yields an advantage for survival in the last decades of life, and that the age-related increase in plasma levels of IL-1Ra seems not to be genetically regulated but a likely safeguard mechanism to buffer the age-associated increased inflammatory state.

Ageing is characterized by a pro-inflammatory status, which could contribute to the onset of major age-related diseases. Thus, genetic variations in pro- or anti-inflammatory cytokines might influence successful ageing and longevity. IL-10 is an appropriate candidate because it exerts powerful inhibitory effects on pro-inflammatory function. IL-10 production is controlled by several polymorphic elements in the 5' flanking region of IL-10 gene on 1q32 locus, involving alleles at two microsatellite regions and several polymorphisms in promoter region. We analysed in 190 Italian centenarians (>99 years old, 159 women and 31 men) and in 260 <60 years old control subjects (99 women and 161 men), matched for geographical distribution, genotype frequencies for -1082G-->A, -819C-->T and -592C-->A IL-10 proximal promoter gene biallelic polymorphisms by sequence specific probes. -1082G homozygous genotype was increased in centenarian men (P < 0.025) but not in centenarian women. No difference was found between centenarians and control subjects regarding the other two polymorphisms. The presence of -1082GG genotype, suggested to be associated with high IL-10 production, significantly increases the possibility to reach the extreme limit of human lifespan in men. Together with previous data on other polymorphic loci (Tyrosine Hydroxylase, mitochondrial DNA, IL-6, haemochromatosis, IFN-gamma), this finding points out that that gender is a major variable in the genetics of longevity, suggesting that men and women follow different strategies to reach longevity. Concerning the biological significance of this association, we have not searched for functional proves that IL-10 is involved. Thus, we should conclude that our data only suggest that a marker on 1q32 genomic region may be involved in successful ageing in man. However, recent data on IL-6 and IFN-gamma genes suggest that longevity is negatively associated with genotypes coding for a pro-inflammatory profile. Thus, it is intriguing that the possession of -1082G genotype, suggested to be associated with IL-10 high production, is significantly increased in centenarians.