Paraoxonase polymorphisms PON1 192 and 55 and longevity in Italian centenarians and Irish nonagenarians. A pooled analysis

Polygenic markers of survival and longevity in the antioxidant genes PON1, PON2, MTHFR, MSRA, SOD1, NQO1, and CAT in a 20-year follow-up study in the population from the Volga-Ural region

BACKGROUND

Genetic background of healthy or pathological styles of aging and human lifespan is determined by joint gene interactions. Lucky combinations of antioxidant gene polymorphisms can result in a highly adaptive phenotype, providing a successful way to interact with external triggers. Our purpose was to identify the polygenic markers of survival and longevity in the antioxidant genes among elderly people with physiological and pathological aging.

METHODS

In a 20-year follow-up study of 2350 individuals aged 18-114 years residing in the Volga-Ural region of Russia, sex-adjusted association analyses of MTHFR rs1801133, MSRA rs10098474, PON1 rs662, PON2 rs7493, SOD1 rs2070424, NQO1 rs1131341 and CAT rs1001179 polymorphic loci with longevity were carried out. Survival analysis was subsequently performed using the established single genes and gene-gene combinations as cofactors.

RESULTS

The PON1 rs662*G allele was defined as the main longevity marker in women (OR = 1.44, p = 3E-04 in the log-additive model; HR = 0.77, p = 1.9E-04 in the Cox-survival model). The polymorphisms in the MTHFR, MSRA, PON2, SOD1, and CAT genes had an additive effect on longevity. A strong protective effect of combined MTHFR rs1801133*C, MSRA rs10098474*T, PON1 rs662*G, and PON2 rs7493*C alleles against mortality was obtained in women (HR = 0.81, p = 5E-03). The PON1 rs662*A allele had a meaningful impact on mortality for both long-lived men with cerebrovascular accidents (HR = 1.76, p = 0.027 for the PON1 rs662*AG genotype) and women with cardiovascular diseases (HR = 1.43, p = 0.002 for PON1 rs662*AA genotype). The MTHFR rs1801133*TT (HR = 1.91, p = 0.036), CAT rs1001179*TT (HR = 2.83, p = 0.031) and SOD1 rs2070424*AG (HR = 1.58, p = 0.018) genotypes were associated with the cancer mortality.

CONCLUSION

In our longitudinal 20-year study, we found the combinations of functional polymorphisms in antioxidant genes involved in longevity and survival in certain clinical phenotypes in the advanced age.

Discovering Biological Mechanisms of Exceptional Human Health Span and Life Span

Humans age at different rates and families with exceptional longevity provide an opportunity to understand why some people age slower than others. Unique features exhibited by centenarians include a family history of extended life span, compression of morbidity with resultant extension of health span, and longevity-associated biomarker profiles. These biomarkers, including low-circulating insulin-like growth factor 1 (IGF-1) and elevated high-density lipoprotein (HDL) cholesterol levels, are associated with functional genotypes that are enriched in centenarians, suggesting that they may be causative for longevity. While not all genetic discoveries from centenarians have been validated, in part due to exceptional life span being a rare phenotype in the general population, the APOE2 and FOXO3a genotypes have been confirmed in a number of populations with exceptional longevity. However, life span is now recognized as a complex trait and genetic research methods to study longevity are rapidly extending beyond classical Mendelian genetics to polygenic inheritance methodologies. Moreover, newer approaches are suggesting that pathways that have been recognized for decades to control life span in animals may also regulate life span in humans. These discoveries led to strategic development of therapeutics that may delay aging and prolong health span.

Association of Serum Paraoxonase 1 Activities, Polymorphisms and Oxidative Stress in Breast Cancer Patients with Type 2 Diabetes Mellitus

Background

The aim of the study was to investigate the association of paraoxonase 1 (PON1) polymorphism, PON1/arylesterase (ARE) activity and oxidative stress index (OSI) in breast cancer (BC) patients with type 2 diabetes (DM).

Methods

Our study group consisted of 30 healthy women (HV group) and 66 female BC patients. The BC patients were divided into two groups: those with (n=37) and without DM (n=29) (BDM and NBDM group). Genotyping of PON1 Q192R and L55M polymorphisms were done by polymerase chain reaction (PCR) - restriction fragment length polymorphism (RFLP) method. Serum PON1/ARE enzyme activities, total oxidant status (TOS) and total antioxidant status (TAS) were analysed by spectrophotometric method. The ratio of TOS to TAS was accepted as the oxidative stress index (OSI).

Results

PON1 Q192R genotype frequency distribution was significantly different in the BDM group compared to the NBDM group (p=0.021). When alleles distribution was examined, R and L alleles were significantly lower, Q and M alleles were significantly higher in the BDM group than in the NBDM group (p<0.001). TOS and OSI were statistically higher in BC patients than HV group (p<0.001).

Conclusions

Our results suggest that PON1 gene Q and M alleles may be the risk factors predisposing formation of BC due to increased oxidant damage seen in DM. However, these statements require further confirmation with screening PON1 polymorphism in a greater number of patients with DM, and also wide range follow-up studies are necessary for the same purpose.

Paraoxonases Activities and Polymorphisms in Elderly and Old-Age Diseases: An Overview

Aging is defined as the accumulation of progressive organ dysfunction. There is much evidence linking the involvement of oxidative stress in the pathogenesis of aging. With increasing age, susceptibility to the development of diseases related to lipid peroxidation and tissue injury increases, due to chronic inflammatory processes, and production of reactive oxygen species (ROS) and free radicals. The paraoxonase (PON) gene family is composed of three members (PON1, PON2, PON3) that share considerable structural homology and are located adjacently on chromosome 7 in humans. The most studied member product is PON1, a protein associated with high-density lipoprotein with paraoxonase/esterase activity. Nevertheless, all the three proteins prevent oxidative stress. The major aim of this review is to highlight the importance of the role of PON enzymes in the aging process, and in the development of the main diseases present in the elderly: cardiovascular disease, diabetes mellitus, neurodegenerative diseases, and cancer.

The evaluation of two genetic polymorphisms of paraoxonase 1 in patients with pulmonary embolism

BACKGROUND AND OBJECTIVE

Pulmonary embolism (PE) is caused by some genetic factors for more than half patients. Paraoxonase 1 (PON1) has significant anti-oxidative and anti-inflammatory effects. According to our knowledge, there is no study researching the relation between PON 1 gene polymorphisms and PE in the literature. Therefore, it is aimed to research possible impacts of PON 1 Q192R and L55M polymorphisms on PE, considering anti-inflammatory and anti-oxidative effects of PON 1 in Turkish population.

METHODS

One hundred and five PE patients and one hundred and seventeen controls were enrolled in this study. Genomic DNA was isolated and genotyped using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analyses for the PON1 gene Q192R and L55M polymorphisms.

RESULTS

Any associations were not found between clinical and demographical characteristics of PE patients and the PON1 gene Q192R polymorphism; however, there were associations between surgery, chronic renal failure, and cerebrovascular disease on the history of patients and L55M polymorphism (P = .013, P = .037, and P = .031, respectively). Genotype and allele frequencies did not show any significant differences between patients and controls according to PON1 gene Q192R and L55M polymorphisms (P > .05).

CONCLUSION

The results of this study suggest that there is no correlation between PE and PON 1 gene Q192R and L55M polymorphisms in the Turkish population from the Central Black Sea region. Besides, whole genotypes and alleles of Q192R and L55M are not risk factors for patients with PE in this population.

Apolipoprotein C-I Polymorphism and Its Association with Serum Lipid Levels and Longevity in the Bama Population

This study aims to determine the association between the apolipoprotein C-I polymorphism and the longevity and genetic variants in ApoC-I that can influence the serum lipid levels in Bama. ApoC-I genotypes were determined by Taqman single nucleotide polymorphism (SNP) genotyping assays in 178 long-lived inhabitants (longevity group aged from 90 to 110 years), 147 healthy controls (Control 1 group aged from 40 to 79 years old) from Bama County, and 190 healthy controls (Control 2 group aged from 40 to 79 years old) from Nandan County without a family history of longevity. Statistical analysis was conducted using SPSS 16.0. All genotype distributions of rs584007 and rs4420638 were consistent with the Hardy-Weinberg equilibrium (p > 0.05). Significant differences were observed in the frequencies of the three genotypes (GG, AG, and AA) among the longevity and the two control groups (χ² = 11.238, p = 0.024) for rs584007. No significant differences were observed in the frequencies of the three genotypes (GG, AG, and AA) among the longevity and the two control groups (χ² = 4.587, p = 0.318) for rs4420638. The levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein-cholesterol (HDL-c), and low-density lipoprotein-cholesterol (LDL-c) were not different among the three genotypes of rs584007 in the three groups. The levels of HDL-c for GG, AG, and AA were significantly different (the highest being in the longevity group), while the levels of TG for AA and AG genotypes (the lowest being in the longevity group) and the levels of LDL-c for AG were significantly different (p < 0.05) among the three groups for rs584007. The levels of TG and HDL-c were significantly different among the three rs4420638 genotypes in the longevity group. The levels of TC for GG, AG, and AA were significantly different in the Control 2 group, while the levels of TG and HDL-c for AA and AG genotypes were significantly different (p < 0.05) among the three groups for rs4420638. The level of HDL-c was highest in the longevity group for AA and AG genotypes, and the level of TG was highest in the Control 2 group for rs4420638. Serum lipid parameters were related to environmental factors, including age, gender, BMI, DBP, SBP, rs4420638, and rs584007. The ApoC-I polymorphism might be one of the genetic factors of longevity in Bama. The ApoC-I rs4420638 and rs584007 SNPs are associated with serum TG and HDL-c levels in the longevous population.

Paraoxonase-1 (PON1) rs662 Polymorphism and Its Association with Serum Lipid Levels and Longevity in the Bama Zhuang Population

Background

The present study was performed to identify the association of PON1 rs662 polymorphism with serum lipid levels and human longevity in the Bama Zhuang population.

Material/Methods

PON1 genotypes were determined by Taqman SNP Genotyping Assays in 110 long-lived inhabitants (longevity group, aged 90–110 years), 110 healthy inhabitants in Bama County (control 1 group, aged 43–82 years) and 110 healthy inhabitants in Nandan County (control 2 group, aged 28–82 years) without family history of longevity.

Results

BMI (body mass index) and TG (serum total triglyceride) level were lower in the longevity group than in the two control groups, while the contents of serum LDL-c (low-density lipoprotein cholesterol) and HDL-c (high-density lipoprotein cholesterol) and the levels of SBP (systolic blood pressure) and DBP (diastolic blood pressure) in the longevity group were higher than in the two control groups (p<0.01). Significant differences in the frequencies of three genotypes (GG, AG, and AA) were observed between the longevity group and control 2 group (χ²=15.190, p=0.001). The minor allele frequency (MAF) of rs662 was significantly higher in the longevity group than in the two control groups. The levels of HDL-c in the longevity group were different among the three genotypes (p<0.05). The levels of TG for GG and GG+AG genotypes were significantly different, while the levels of TC (total cholesterol) and HDL-c for AG and GG+AG genotypes were significantly different among the three groups (p<0.05). Serum lipid parameters were correlated with several environmental factors, including age, gender, DBP, SBP, and BMI. The association of PON1 rs662 polymorphism and serum lipid levels was different among the three groups.

Conclusions

PON1 polymorphism might be one of the genetic factors of longevity in the Bama Zhuang population. The PON1 rs662 SNP (single nucleotide polymorphism) was associated with serum HDL-c levels in the longevity group.

Dissecting the Mechanisms Underlying Unusually Successful Human Health Span and Life Span

Humans age at different rates and families with exceptional survival provide the opportunity to understand why some people age slower than others. Unique features exhibited by centenarians include a family history of longevity, compression of morbidity with resultant extension of health span, and biomarkers such as low-circulating insulin-like growth factor 1 (IGF-1) and elevated high-density lipoprotein (HDL) cholesterol levels. Given the rarity of the centenarian phenotype, it has not been surprising that the use of discovery methods that relied on common population single nucleotide polymorphisms (SNPs) to unlock the genetic determinants of exceptional longevity have not yielded significant results. Conversely, gene sequencing has resulted in discoveries of functional gene variants that support several of the centenarian phenotypes. These discoveries have led to the strategic developments of drugs that may delay aging and prolong health span.

Paraoxonase (PON1) polymorphisms Q192R and L55M are not associated with human longevity: A meta-analysis

BACKGROUND

Genetic mutations in the paraoxonase 1 (PON1) encoding gene have been considered to affect mortality and of these the functional promoter region polymorphisms Q192R and L55M are among the most widely studied.

OBJECTIVE

The aim of this study was to determine whether the Q192R and L55M polymorphisms of PON1 can increase susceptibility to longevity. A meta-analysis was performed to obtain a comprehensive estimation of the association between Q192R and L55M and longevity in long-lived individuals (LLIs) aged 80 years or more.

MATERIAL AND METHODS

A search was carried out in the PubMed database (from January 2001 to May 2014) to obtain data on the role of PON1 polymorphisms in longevity and a pooled odds ratio (OR) with a 95% confidence interval (CI) was used to assess the associations.

RESULTS

The meta-analysis was based on 9 studies of PON1 Q192R and 5 studies of PON1 L55M that covered a total of 5086 LLIs and 4494 controls. Overall, significantly increased risks were not observed for either Q192R or L55M. The results of the statistical calculations were as follows: R vs. Q (additive model): OR = 1.080, 95% CI = 0.989-1.179, p = 0.088 and RR + RQ vs. QQ (dominant model): OR = 1.099, 95% CI = 0.975-1.240, p = 0.124; M vs. L (additive model): OR = 0.946, 95% CI = 0.862-1.039, p = 0.245 and MM + ML vs. LL (dominant model): OR = 0.951, 95% CI = 0.836-1.081, p = 0.442 for Q192R and L55M, respectively. The results did not change with an age cut-off among the LLIs of ≥ 93 years.

CONCLUSION

No evidence that the Q192R and L55M polymorphisms of PON1 impacted on the probability of reaching extreme ages was found although this cannot be completely ruled out; however, the possibility of population-specific effects due to the influence of and interaction between different genes or environmental factors could not be ruled out.

Immunomodulatory role of high-density lipoproteins: impact on immunosenescence

Natural aging is accompanied by a dysregulation of the host immune response that has well-known clinical consequences but poorly defined underlying causes. It has previously been reported that advancing age is associated with an increase in membrane cholesterol level in T cells. The aim of this study was to investigate whether high-density lipoprotein (HDL) can modulate the age-related accumulation of membrane cholesterol in T cells and impact on their subsequent responsiveness. Our data reveal that cholesterol metabolism, influx, and efflux are altered in T cells with aging, which may in part explain the increase in membrane cholesterol level observed in T cells in elderly individuals. HDL was unable to promote reverse cholesterol transport in T cells from elderly subjects with the same efficiency as was observed in T cells from young subjects besides unchanged ABCA-1 and SR-BI expressions. HDL exhibited a short-acting co-stimulatory effect by enhancing T cell production of interleukin-2 (IL-2). Moreover, HDL from healthy normolipemic individuals exerted differential effects on T cell proliferation that depended on the age of the HDL donor. Finally, HDL modulated TCR/CD28 activation by inducing sustained signaling through pLck, pERK, and pAkt. These data suggest that HDL has immunomodulatory effects on T cells that are influenced by age.

Paraoxonase 1 polymorphisms within a Mississippi USA population as possible biomarkers of enzyme activities associated with disease susceptibility

Paraoxonase (PON1) hydrolyzes paraoxon (PO) and diazoxon (DZO), active metabolites of insecticides parathion and diazinon. The PON1 gene has single nucleotide polymorphisms (SNPs) including a codon 192 arginine (R) to glutamine (Q) and methionine (M) to leucine (L) at codon 55. Hydrolysis of PO (POase), DZO (DZOase), dihydrocoumarin (lactonase), and phenyl acetate (arylesterase) were evaluated for associations with race, gender, age, and PON1 55/192 SNP genotypes. Variables were analyzed both individually and in combination. QQ individuals had higher lactonase (p < 0.001) than RR individuals. This might partially explain why predominantly RR African Americans have higher rates of coronary disease than predominantly QQ Caucasians. Significant (p < 0.001) differences in arylesterase were seen among genotypes with QQ and MM lowest whereas RR and LL were highest. This opposes the prevailing belief that arylesterase is unaffected by genotype and suggests that this activity cannot be used to quantify PON1 protein.

Exploring the role of genetic variability and lifestyle in oxidative stress response for healthy aging and longevity

Oxidative stress is both the cause and consequence of impaired functional homeostasis characterizing human aging. The worsening efficiency of stress response with age represents a health risk and leads to the onset and accrual of major age-related diseases. In contrast, centenarians seem to have evolved conservative stress response mechanisms, probably derived from a combination of a diet rich in natural antioxidants, an active lifestyle and a favorable genetic background, particularly rich in genetic variants able to counteract the stress overload at the level of both nuclear and mitochondrial DNA. The integration of these factors could allow centenarians to maintain moderate levels of free radicals that exert beneficial signaling and modulator effects on cellular metabolism. Considering the hot debate on the efficacy of antioxidant supplementation in promoting healthy aging, in this review we gathered the existing information regarding genetic variability and lifestyle factors which potentially modulate the stress response at old age. Evidence reported here suggests that the integration of lifestyle factors (moderate physical activity and healthy nutrition) and genetic background could shift the balance in favor of the antioxidant cellular machinery by activating appropriate defense mechanisms in response to exceeding external and internal stress levels, and thus possibly achieving the prospect of living a longer life.

Human serum paraoxonase gene polymorphisms, Q192R and L55M, are not associated with the risk of cerebral infarction in Chinese Han population

OBJECTIVES

It has been reported that human serum paraoxonase (PON1) gene is associated with coronary heart disease (CHD) and diabetes mellitus (DM). However, little is known about the role of PON1 gene polymorphism in cerebral infarction (CI). For this, we have investigated the relationship between PON1 gene polymorphisms, Q192R and L55M, and CI in Chinese Han population.

METHODS

The PON1 genotypes, Q192R and L55M, from 153 CI patients and 153 healthy individuals, were determined by polymerase chain reaction (PCR) and restriction enzyme digestion. Their allele frequencies were then determined. The association of the PON1 gene polymorphism with the risk of CI was analysed by statistical analysis software.

RESULTS

The frequencies of PON1-Q192R genotypes in CI and control group are 13.7 and 9.8% (QQ), 51.6 and 53.6% (QR), 34.6 and 36.6% (RR) respectively. There is no significant difference in PON1-Q192R genotype (p=0.566) and allele frequencies (p=0.505) between CI patients and controls. The frequencies of PON1-55 genotypes in the CI and control group are 96.7 and 93.5% (LL), 3.3 and 6.5% (LM) respectively. No MM genotype was found in both CI and control group. No significant difference in genotype (p=0.289) and allele (p=0.296) distribution between CI patients and controls was observed.

DISCUSSION

Our results suggest that the human serum paraoxonase polymorphisms, Q192R and L55M, are not associated with the risk of cerebral infarction in Chinese Han population.

Two- and three-locus haplotypes of the paraoxonase (PON1) gene are associated with coronary artery disease in Asian Indians

INTRODUCTION

In view of the reported association of SNPs in the paraoxonase (PON1) gene with coronary artery disease (CAD), and the absence of conclusive data from India, we investigated the relationship of three SNPs at different loci (-108C/T, L55M and Q192R) of the PON1 gene and their haplotypes with CAD among people residing in the northern plains of India.

MATERIALS AND METHODS

One hundred and seventy-eight healthy controls and two hundred and four angiographically-proven CAD patients were genotyped using PCR-RFLP.

RESULTS

Of the three SNPs, only the R allele of Q192R polymorphism was associated with CAD (p<0.05). Two locus haplotypes QT (OR 0.55, p=0.0004, 95% CI 0.39-0.77, significant) and LQ (odds ratio 0.73, p=0.03, 95% CI 0.55-0.97, trend) showed protective effects, while haplotypes MR (OR=5.36, p=0.0001, 95% CI 2.045-14.049) and MC (OR=2.71, p=0.011, 95% CI 1.221-6.046) were associated with increased risk of CAD. MRT, a minor three-locus haplotype also displayed significant association (OR 4.93, 95% CI 1.7-13.5) with the disease. Significance was assessed after applying Bonferroni's correction.

CONCLUSIONS

Our study revealed that only one SNP at a single locus but several haplotype combinations of PON1 coding and promoter-region polymorphisms were associated with the risk of or protection against CAD. Thus, haplotype analysis brought better insights into the association of PON1 gene polymorphisms with CAD in Asian Indians.

The human paraoxonase gene cluster as a target in the treatment of atherosclerosis

The paraoxonase (PON) gene cluster contains three adjacent gene members, PON1, PON2, and PON3. Originating from the same fungus lactonase precursor, all of the three PON genes share high sequence identity and a similar β propeller protein structure. PON1 and PON3 are primarily expressed in the liver and secreted into the serum upon expression, whereas PON2 is ubiquitously expressed and remains inside the cell. Each PON member has high catalytic activity toward corresponding artificial organophosphate, and all exhibit activities to lactones. Therefore, all three members of the family are regarded as lactonases. Under physiological conditions, they act to degrade metabolites of polyunsaturated fatty acids and homocysteine (Hcy) thiolactone, among other compounds. By detoxifying both oxidized low-density lipoprotein and Hcy thiolactone, PONs protect against atherosclerosis and coronary artery diseases, as has been illustrated by many types of in vitro and in vivo experimental evidence. Clinical observations focusing on gene polymorphisms also indicate that PON1, PON2, and PON3 are protective against coronary artery disease. Many other conditions, such as diabetes, metabolic syndrome, and aging, have been shown to relate to PONs. The abundance and/or activity of PONs can be regulated by lipoproteins and their metabolites, biological macromolecules, pharmacological treatments, dietary factors, and lifestyle. In conclusion, both previous results and ongoing studies provide evidence, making the PON cluster a prospective target for the treatment of atherosclerosis.

Inflammation and genetics: an insight in the centenarian model

The number of centenarians is growing worldwide. This specific cohort has aroused the attention of scientists worldwide and is considered one of the most valuable models to study the mechanisms involved in the aging process. In fact, they have reached the extreme limits of human life span and, most important of all, they show relatively good health being able to perform their routine daily life. Because they have escaped the common lethal diseases, the role of their genetic background has been brought into focus. In fact, sequence variations, in a variety of pro- or anti-inflammatory cytokine genes, have been found to influence successful ageing and longevity. The key role played by cytokines has been also confirmed in centenarians as we know that inflammation has been related to several pathological burdens (e.g., obesity, atherosclerosis, and diabetes). Successful ageing seems to be related to an optimal functioning of the immune system, pointing out that polymorphisms for the immune system genes, which are involved in the regulation of immune-inflammatory responses, may play a key role in the genetics of ageing. This review provides an update in the field of ageing related to inflammation and genetics.

Ideal lipid profile and genes for an extended life span

PURPOSE OF REVIEW

The world population is aging and a rapid increase is being seen in the very elderly (aged >80 years). Cholesterol levels in general rise with age and high cholesterol has been associated with extreme longevity. The relationship between lipids and cardiovascular events in the extreme elderly is unclear.

RECENT FINDINGS

A number of genetic factors associated with lipid metabolism have also been described as having potential antiaging roles, including the genes encoding lipoprotein-associated factors - apolipoprotein E and cholesterol ester transfer protein; adipose tissue metabolism - adiponectin, leptin, glycaemia; and blood pressure - angiotensinogen. Clinical trials of lipid-lowering therapies have recruited subgroups of moderately elderly patients, but only the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER) trial specifically recruited an elderly population. There is no direct equivalent of the Hypertension in the Very Elderly trial (HYVET) study of antihypertensive patients in the extreme elderly. No heterogeneity has been seen with the effects of statin therapy in the elderly compared with younger age groups on classical cardiovascular endpoints of coronary heart disease and stroke.

SUMMARY

The optimal cholesterol target, long-term tolerability and the specific effects of statins on other vascular-associated diseases of aging, for example arterial aneurysms, microvascular renal and cerebral disease (dementias), remain to be determined.

The role of genetic variants in human longevity

Human longevity is a complex phenotype with a strong genetic predisposition. Increasing evidence has revealed the genetic antecedents of human longevity. This article aims to review the data of various case/control association studies that examine the difference in genetic polymorphisms between long-lived people and younger subjects across different human populations. There are more than 100 candidate genes potentially involved in human longevity; this article particularly focuses on genes of the insulin/IGF-1 pathway, FOXO3A, FOXO1A, lipoprotein metabolism (e.g., APOE and PON1), and cell-cycle regulators (e.g., TP53 and P21). Since the confirmed genetic components for human longevity are few to date, further precise assessment of the genetic contributions is required. Gaining a better understanding of the contribution of genetics to human longevity may assist in the design of improved treatment methods for age-related diseases, delay the aging process, and, ultimately, prolong the human lifespan.

No or only population-specific effect of PON1 on human longevity: a comprehensive meta-analysis

Paraoxonase 1 (PON1) has been suggested as a plausible candidate gene for human longevity due to its modulation of cardiovascular disease risk, by preventing oxidation of atherogenic low-density lipoprotein. The role of the PON1 192 Q/R polymorphism has been analyzed for association with survival at old age in several populations, albeit with controversial results. To reconcile the conflicting evidence, we performed a large association study with two samples of 2357 Germans and 1025 French, respectively. We combined our results with those from seven previous studies in the largest and most comprehensive meta-analysis on PON1 192 Q/R and longevity to-date, to include a total of 9580 individuals. No significant association of PON1 192 Q/R with longevity was observed, for either R allele or carriership. This finding relied on very large sample sizes, is supported by different analysis methods and is therefore considered very robust. Moreover, we have investigated a potential interaction of PON1 192 Q/R with APOE epsilon4 using data from four populations. Whereas a significant result was found in the German sample, this could not be confirmed in the other examined groups. Our large-scale meta-analysis provided no evidence that the PON1 192 Q/R polymorphism is associated with longevity, but this does not exclude the possibility of population-specific effects due to the influence of, and interaction between, different genetic and/or environmental factors (e.g. diet).

Single nucleotide polymorphisms in obesity-related genes and all-cause and cause-specific mortality: a prospective cohort study

Background

The aim of this study was to examine the associations between 16 specific single nucleotide polymorphisms (SNPs) in 8 obesity-related genes and overall and cause-specific mortality. We also examined the associations between the SNPs and body mass index (BMI) and change in BMI over time.

Methods

Data were analyzed from 9,919 individuals who participated in two large community-based cohort studies conducted in Washington County, Maryland in 1974 (CLUE I) and 1989 (CLUE II). DNA from blood collected in 1989 was genotyped for 16 SNPs in 8 obesity-related genes: monoamine oxidase A (MAOA), lipoprotein lipase (LPL), paraoxonase 1 and 2 (PON1 and PON2), leptin receptor (LEPR), tumor necrosis factor-α (TNFα), and peroxisome proliferative activated receptor-γ and -δ (PPARG and PPARD). Data on height and weight in 1989 (CLUE II baseline) and at age 21 were collected from participants at the time of blood collection. All participants were followed from 1989 to the date of death or the end of follow-up in 2005. Cox proportional hazards regression was used to obtain the relative risk (RR) estimates and 95% confidence intervals (CI) for each SNP and mortality outcomes.

Results

The results showed no patterns of association for the selected SNPs and the all-cause and cause-specific mortality outcomes, although statistically significant associations (p < 0.05) were observed between PPARG rs4684847 and all-cause mortality (CC: reference; CT: RR 0.99, 95% CI 0.89, 1.11; TT: RR 0.60, 95% CI 0.39, 0.93) and cancer-related mortality (CC: reference; CT: RR 1.01, 95% CI 0.82, 1.25; TT: RR 0.22, 95% CI 0.06, 0.90) and TNFα rs1799964 and cancer-related mortality (TT: reference; CT: RR 1.23, 95% CI 1.03, 1.47; CC: RR 0.83, 95% CI 0.54, 1.28). Additional analyses showed significant associations between SNPs in LEPR with BMI (rs1137101) and change in BMI over time (rs1045895 and rs1137101).

Conclusion

Findings from this cohort study suggest that the selected SNPs are not associated with overall or cause-specific death, although several LEPR SNPs may be related to BMI and BMI change over time.

PON1 is a longevity gene: results of a meta-analysis

Paraoxonase 1 (PON1) is one of the most studied genes regarding cardiovascular risk, oxidative stress and inflammation. Several lines of evidence suggests that PON1 promotes an atheroprotective effect. Patients carrying PON1 codon 192 QQ genotype display a higher risk of cardiovascular events, the major cause of mortality in the elderly: it can be predicted that gene variants increasing the risk of mortality will be under-represented in long-living individuals. We first reported that PON1 R allele (R+) carriers are significantly more represented in Italian centenarians; subsequently this topic has been addressed by many other groups, and here we report a meta-analysis on 11 studies in different populations selected by a review of the literature available in PubMed and testing the effect of the Q192R polymorphism on human ageing. QUORUM guidelines for meta-analysis have been followed, and a total number of 5962 subjects have been included: 2795 young controls (<65 years of age) and 3167 old subjects (>65 years of age). The Mantel-Haenszel weighting for pooling in presence of a fixed effects model has been applied. The meta-analysis of R carriers showed a significant result with an overall OR of 1.16 (1.04-1.30, 95% CI, p=0.006). The meta-analysis of QR genotype also showed a significant result, with an overall OR of 1.14 (1.02-1.27, 95% CI, p=0.016). The results show that PON1 gene variants at codon 192 impact on the probability of attaining longevity, and that subjects carrying RR and QR genotypes (R+ carriers) are favoured in reaching extreme ages. These results likely represent the counterpart of the effects observed on cardiovascular diseases (CVD), as centenarians and nonagenarians escaped or delayed the onset of the major age-related diseases, including CVD.

Paraoxonase: a multifaceted biomolecule

BACKGROUND

Paraoxonase enzyme was first identified as a protective barrier against organophosphorus poisoning. After painstaking research spanning the last three decades, the knowledge about this enzyme has increased immensely. The present review attempts to elaborate the role of paraoxonase enzyme in normal physiology as well as provide an overview of the various disorders in which the enzyme may have a role in etiopathogenesis.

METHODS

The literature was searched from the websites of the National Library of Medicine (http://www.ncbi.nlm.nih.gov/) and Pub Med Central, the U.S. National Library of Medicine's digital archive of life sciences journal literature.

RESULTS

Paraoxonase acts as an important antioxidant enzyme against oxidative stress. The enzyme has been implicated in the pathogenesis of a number of disorders including cardiovascular disorders, cancers etc.

CONCLUSIONS

A better understanding of the molecular mechanism of the enzyme along with the regulatory circuits will help us to utilize agonists to potentiate the anti oxidant actions of the enzyme.

Genetic variation in healthy oldest-old

Individuals who live to 85 and beyond without developing major age-related diseases may achieve this, in part, by lacking disease susceptibility factors, or by possessing resistance factors that enhance their ability to avoid disease and prolong lifespan. Healthy aging is a complex phenotype likely to be affected by both genetic and environmental factors. We sequenced 24 candidate healthy aging genes in DNA samples from 47 healthy individuals aged eighty-five years or older (the 'oldest-old'), to characterize genetic variation that is present in this exceptional group. These healthy seniors were never diagnosed with cancer, cardiovascular disease, pulmonary disease, diabetes, or Alzheimer disease. We re-sequenced all exons, intron-exon boundaries and selected conserved non-coding sequences of candidate genes involved in aging-related processes, including dietary restriction (PPARG, PPARGC1A, SIRT1, SIRT3, UCP2, UCP3), metabolism (IGF1R, APOB, SCD), autophagy (BECN1, FRAP1), stem cell activation (NOTCH1, DLL1), tumor suppression (TP53, CDKN2A, ING1), DNA methylation (TRDMT1, DNMT3A, DNMT3B) Progeria syndromes (LMNA, ZMPSTE24, KL) and stress response (CRYAB, HSPB2). We detected 935 variants, including 848 single nucleotide polymorphisms (SNPs) and 87 insertion or deletions; 41% (385) were not recorded in dbSNP. This study is the first to present a comprehensive analysis of genetic variation in aging-related candidate genes in healthy oldest-old. These variants and especially our novel polymorphisms are valuable resources to test for genetic association in models of disease susceptibility or resistance. In addition, we propose an innovative tagSNP selection strategy that combines variants identified through gene re-sequencing- and HapMap-derived SNPs.

Genetic polymorphism in long-lived people: cues for the presence of an insulin/IGF-pathway-dependent network affecting human longevity

Longevity in yeast, nematodes, fruit flies and mice is affected by mutations in the insulin/IGF-1 or homologous pathways. Studies on long-living people revealed some associations between genetic variants of the insulin/IGF-1 pathway and longevity. Here, we review such investigations, and we will report human longevity association studies regarding the variability of genes which modulate lifespan in model organisms by interacting with the insulin/IGF-1 pathway. These studies will be presented in three groups: (1) insulin/IGF-1 pathway transcriptional target, superoxide dismutase 2, heat shock protein, cytochrome p450 isoenzymes, glutathione transferases; (2) insulin/IGF-1 pathway accessory transduction proteins H-Ras, p66Shc; and (3) longevity pathways that converge on the insulin/IGF-1 pathway (Klotho, p53, Sirtuins, TGF-beta). The data reported support the notion that the insulin/IGF-1 pathway drives an evolutionarily conserved network that regulates lifespan and affects longevity across species.

Genetic epidemiology in aging research

Over the last two decades, aging research has expanded to include not only age-related disease models, and conversely, longevity and disease-free models, but also focuses on biological mechanisms related to the aging process. By viewing aging on multiple research frontiers, we are rapidly expanding knowledge as a whole and mapping connections between biological processes and particular age-related diseases that emerge. This is perhaps most true in the field of genetics, where variation across individuals has improved our understanding of aging mechanisms, etiology of age-related disease, and prediction of therapeutic responses. A close partnership between gerontologists, epidemiologists, and geneticists is needed to take full advantage of emerging genome information and technology and bring about a new age for biological aging research. Here we review current genetic findings for aging across both disease-specific and aging process domains. We then highlight the limitations of most work to date in terms of study design, genomic information, and trait modeling and focus on emerging technology and future directions that can partner genetic epidemiology and aging research fields to best take advantage of the rapid discoveries in each.

Prevalence in the United States of selected candidate gene variants: Third National Health and Nutrition Examination Survey, 1991-1994

Population-based allele frequencies and genotype prevalence are important for measuring the contribution of genetic variation to human disease susceptibility, progression, and outcomes. Population-based prevalence estimates also provide the basis for epidemiologic studies of gene-disease associations, for estimating population attributable risk, and for informing health policy and clinical and public health practice. However, such prevalence estimates for genotypes important to public health remain undetermined for the major racial and ethnic groups in the US population. DNA was collected from 7,159 participants aged 12 years or older in Phase 2 (1991-1994) of the Third National Health and Nutrition Examination Survey (NHANES III). Certain age and minority groups were oversampled in this weighted, population-based US survey. Estimates of allele frequency and genotype prevalence for 90 variants in 50 genes chosen for their potential public health significance were calculated by age, sex, and race/ethnicity among non-Hispanic whites, non-Hispanic blacks, and Mexican Americans. These nationally representative data on allele frequency and genotype prevalence provide a valuable resource for future epidemiologic studies in public health in the United States.

Zinc-gene interaction related to inflammatory/immune response in ageing

The pivotal role played by zinc-gene interaction in affecting some relevant cytokines (IL-6 and TNF-alpha) and heat shock proteins (HSP70-2) in ageing, successful ageing (nonagenarians) and the most common age-related diseases, such as atherosclerosis and infections, is now recognized. The polymorphisms of genes codifying proteins related to the inflammation are predictive on one hand in longevity, on the other hand they are associated with atherosclerosis or severe infections. Since the health life-span has a strong genetic component, which in turn also affected by nutritional factors like zinc, the association of these polymorphisms with innate immune response, zinc ion bioavailability and Metallothioneins (MT) homeostasis is an useful tool to unravel the role played by zinc-gene interactions in longevity, especially due to the inability of MT in zinc release in ageing and chronic inflammation. In ageing, this last fact leads to depressed innate immune response for host defence. In contrast, in very old age the inflammation is lower with subsequent more zinc ion bioavailability, less MT gene expression and satisfactory innate immunity. Therefore, the zinc-gene (IL-6, TNF-alpha, Hsp70-2) interactions, via MT homeostasis, are crucial to achieve successful ageing.

Study on a possible effect of four longevity candidate genes (ACE, PON1, PPAR-gamma, and APOE) on human fertility

The present study investigated for a possible effect on fertility of four longevity candidate genes (ACE, PON1, PPAR-gamma, APOE) in order to determine whether they have a pleiotropic action at different life ages. The study population was 151 healthy unrelated subjects. Only PPAR-gamma and APOE showed an effect on fertility. The PPAR-gamma Pro/Ala genotype, which had showed an association with longevity only in men, was found associated only in men with having produced more children (6.1+/-3.3) than the Pro/Pro genotype (3.3+/-1.9; P=0.001). APOE*2 allele, which has been consistently associated with longevity, was confirmed to be associated with the lowest fertility (P=0.03). The logistic regression analysis indicated that APOE and PPAR-gamma polymorphisms may be considered independent determinants of reproductive efficiency. These data suggest that the APOE*2 allele follows the model of antagonist pleiotropy, while the PPAR-gamma Pro/Ala genotype seems to exert beneficial effects both early in life and in advanced age in a gender-specific way.

Genetic determinants of human health span and life span: progress and new opportunities

We review three approaches to the genetic analysis of the biology and pathobiology of human aging. The first and so far the best-developed is the search for the biochemical genetic basis of varying susceptibilities to major geriatric disorders. These include a range of progeroid syndromes. Collectively, they tell us much about the genetics of health span. Given that the major risk factor for virtually all geriatric disorders is biological aging, they may also serve as markers for the study of intrinsic biological aging. The second approach seeks to identify allelic contributions to exceptionally long life spans. While linkage to a locus on Chromosome 4 has not been confirmed, association studies have revealed a number of significant polymorphisms that impact upon late-life diseases and life span. The third approach remains theoretical. It would require longitudinal studies of large numbers of middle-aged sib-pairs who are extremely discordant or concordant for their rates of decline in various physiological functions. We can conclude that there are great opportunities for research on the genetics of human aging, particularly given the huge fund of information on human biology and pathobiology, and the rapidly developing knowledge of the human genome.

Successful aging: from phenotype to genotype

Despite worldwide interest in the increasing human "healthspan," inadequate experimental attention has been dedicated to identifying genetic influences on successful aging beyond those that influence longevity alone. Although it is an under-studied topic, some promising leads have emerged from the existing genetic studies of successful aging. Here we describe the results of a systematic review of published family, twin, linkage, and association studies of successful aging that evaluated at least one other characteristic of healthy aging in addition to longevity. We identified 29 studies that met our criteria. Although methodological inconsistencies in sampling and phenotypes were frequent, we found evidence for a substantial genetic contribution to successful aging, including several specific genes (APOE, GSTT1, IL6, IL10, PON1, and SIRT3) that are promising candidates for future molecular genetic research. In addition to reviewing this literature, we provide recommendations for advancing our understanding of the genetic basis of successful aging.

Genes, ageing and longevity in humans: problems, advantages and perspectives

Many epidemiological data indicate the presence of a strong familial component of longevity that is largely determined by genetics, and a number of possible associations between longevity and allelic variants of genes have been described. A breakthrough strategy to get insight into the genetics of longevity is the study of centenarians, the best example of successful ageing. We review the main results regarding nuclear genes as well as the mitochondrial genome, focusing on the investigations performed on Italian centenarians, compared to those from other countries. These studies produced interesting results on many putative "longevity genes". Nevertheless, many discrepancies are reported, likely due to the population-specific interactions between gene pools and environment. New approaches, including large-scale studies using high-throughput techniques, are urgently needed to overcome the limits of traditional association studies performed on a limited number of polymorphisms in order to make substantial progress to disentangle the genetics of a trait as complex as human longevity.

Genetic determinants of exceptional human longevity: insights from the Okinawa Centenarian Study

Centenarians represent a rare phenotype appearing in roughly 10-20 per 100,000 persons in most industrialized countries but as high as 40-50 per 100,000 persons in Okinawa, Japan. Siblings of centenarians in Okinawa have been found to have cumulative survival advantages such that female centenarian siblings have a 2.58-fold likelihood and male siblings a 5.43-fold likelihood (versus their birth cohorts) of reaching the age of 90 years. This is indicative of a strong familial component to longevity. Centenarians may live such extraordinarily long lives in large part due to genetic variations that either affect the rate of aging and/or have genes that result in decreased susceptibility to age-associated diseases. Some of the most promising candidate genes appear to be those involved in regulatory pathways such as insulin signaling, immunoinflammatory response, stress resistance or cardiovascular function. Although gene variants with large beneficial effects have been suggested to exist, only APOE, an important regulator of lipoproteins has been consistently associated with a longer human lifespan across numerous populations. As longevity is a very complex trait, several issues challenge our ability to identify its genetic influences, such as control for environmental confounders across time, the lack of precise phenotypes of aging and longevity, statistical power, study design and availability of appropriate study populations. Genetic studies on the Okinawan population suggest that Okinawans are a genetically distinct group that has several characteristics of a founder population, including less genetic diversity, and clustering of specific gene variants, some of which may be related to longevity. Further work on this population and other genetic isolates would be of significant interest to the genetics of human longevity.

Inflammaging and anti-inflammaging: a systemic perspective on aging and longevity emerged from studies in humans

A large part of the aging phenotype, including immunosenescence, is explained by an imbalance between inflammatory and anti-inflammatory networks, which results in the low grade chronic pro-inflammatory status we proposed to call inflammaging. Within this perspective, healthy aging and longevity are likely the result not only of a lower propensity to mount inflammatory responses but also of efficient anti-inflammatory networks, which in normal aging fail to fully neutralize the inflammatory processes consequent to the lifelong antigenic burden and exposure to damaging agents. Such a global imbalance can be a major driving force for frailty and common age-related pathologies, and should be addressed and studied within an evolutionary-based systems biology perspective. Evidence in favor of this conceptualization largely derives from studies in humans. We thus propose that inflammaging can be flanked by anti-inflammaging as major determinants not only of immunosenescence but eventually of global aging and longevity.

The quest for genetic determinants of human longevity: challenges and insights

Twin studies show that genetic differences account for about a quarter of the variance in adult human lifespan. Common polymorphisms that have a modest effect on lifespan have been identified in one gene, APOE, providing hope that other genetic determinants can be uncovered. However, although variants with substantial beneficial effects have been proposed to exist and several candidates have been put forward, their effects have yet to be confirmed. Human studies of longevity face numerous theoretical and logistical challenges, as the determinants of lifespan are extraordinarily complex. However, large-scale linkage studies of long-lived families, longitudinal candidate-gene association studies and the development of analytical methods provide the potential for future progress.

Paraoxonase Activity and Genotype Predispose to Successful Aging

The paraoxonase 1 codon 192 R allele has been previously reported to have a role in successful aging. The relationship between PON1 genotypes, enzymatic activity, and mass concentration was evaluated in a group of 229 participants from 22 to 104 years of age, focusing our attention on nonagenarian/centenarian participants. We found a genetic control for paraoxonase activity that is maintained throughout life, also in the nonagenarians/centenarians. This activity decreases significantly during aging and shows different mean values among R and M carriers, where R+ and M- carriers have the significant highest paraoxonase activity. Results from the multinomial regression logistic model show that paraoxonase activity as well as R+ and M- carriers contribute significantly to the explanation of the longevity phenotype. In conclusion, we show that genetic variability at the PON1 locus is related to paraoxonase activity throughout life, and suggest that both parameters affect survival at extreme advanced age.

A Polymorphism of the YTHDF2 Gene (1p35) Located in an Alu-Rich Genomic Domain Is Associated With Human Longevity

The uneven distribution of Alu repetitive elements in the human genome is related to specific functional properties of genomic regions. We report the identification of a locus associated with human longevity in one of the chromosomal regions with the highest density of Alu elements, in 1p35. The locus, corresponding to a (TG)n microsatellite in the YTHDF2 gene, was identified by characterizing an "anonymous" marker detectable through inter-Alu fingerprinting, which previously evidenced an increased homozygosity in centenarians. After genotyping 412 participants of different ages, including 137 centenarians, we confirmed the increased homozygosity in centenarians at this locus, and observed a concomitantly increased frequency of the most frequent allele and the corresponding homozygous genotype. Remarkably, the same genotype was associated with increased YTHDF2 messenger RNA levels in immortalized lymphocytes. Finally, YTHDF2 messenger RNA resulted to be mainly expressed in testis and placenta. The data suggest a possible role of this locus in human longevity.

The Genetics of Human Longevity

Aging is due to a complex interaction of genetic, epigenetic, and environmental factors, but a strong genetic component appears to have an impact on survival to extreme ages. In order to identify "longevity genes" in humans, different strategies are now available. In our laboratory, we performed association studies on a variety of "candidate" polymorphisms in Italian centenarians. Many genes/polymorphisms gave negative results, while others showed a positive association with human longevity and a sometimes-positive association with unsuccessful aging (myocardial infarction, Alzheimer's disease, and type 2 diabetes). Results regarding genes involved in inflammation (IL-1 cluster, IL-6, IL-10, TNF-alpha, TGF-beta, TLR-4, PPARgamma), insulin/IGF-1 signaling pathway and lipid metabolism (apolipoproteins, CETP, PON1), and oxidative stress (p53, p66(shc)) will be described. In addition, a strong role of the interaction between nuclear and mitochondrial genomes (mtDNA haplogroups and the C150T mutation) emerged from our findings. Thus, the genetics of human longevity appears to be quite peculiar in a context where antagonistic pleiotropy can play a major role and genes can have a different biological role at different ages.

Search for genetic variants in the p66Shc longevity gene by PCR-single strand conformational polymorphism in patients with early-onset cardiovascular disease

Background

Among the possible candidate genes for atherosclerosis experimental data point towards the longevity gene p66^Shc. The p66^Shc gene determines an increase of intracellular reactive oxygen species (ROS), affecting the rate of oxidative damage to nucleic acids. Knock-out p66^Shc-/- mice show reduction of systemic oxidative stress, as well as of plasma LDL oxidation, and reduced atherogenic lesions. Thus, p66^Shc may play a pivotal role in controlling oxidative stress and vascular dysfunction in vivo.

Methods

We searched for sequence variations in the p66^Shc specific region of the Shc gene and its upstream promoter by PCR-SSCP in a selected group of early onset coronary artery disease (CAD) subjects (n. 78, mean age 48.5 ± 6 years) and in 93 long-living control subjects (mean age 89 ± 6 years).

Results

The analysis revealed two variant bands. Sequencing of these variants showed two SNPs: -354T>C in the regulatory region of p66^Shc locus and 92C>T in the p66 specific region (CH2). Both these variants have never been described before. The first substitution partially modifies the binding consensus sequence of the Sp1 transcription factor, and was detected only in two heterozygous carriers (1 CAD subjects and 1 control subject). The 92C>T substitution in the CH2 region consists in an amino acid substitution at codon 31 (proline to leucine, P31L), and was detected in heterozygous status only in one CAD subject. No subjects homozygous for the two newly described SNPs were found.

Conclusion

Only two sequence variations in the p66^Shc gene were observed in a total of 171 subjects, and only in heterozygotes. Our observations, in accordance to other studies, suggest that important variations in the p66^Shc gene may be extremely rare and probably this gene is not involved in the genetic susceptibility to CAD.

Disentangling the genetic determinants of human aging: biological age as an alternative to the use of survival measures

The choice of a phenotype is critical for the study of a complex genetically regulated process, such as aging. To date, most of the twin and family studies have focused on broad survival measures, primarily age at death or exceptional longevity. However, on the basis of recent studies of twins and families, biological age has also been shown to have a strong genetic component, with heritability estimates ranging from 27% to 57%. The aim of this review is twofold: first, to summarize growing consensus on reliable methods of biological age assessment, and second, to demonstrate validity of this phenotype for research in the genetics of aging in humans.

Genes involved in immune response/inflammation, IGF1/insulin pathway and response to oxidative stress play a major role in the genetics of human longevity: the lesson of centenarians

In this paper, we review data of recent literature on the distribution in centenarians of candidate germ-line polymorphisms that likely affect the individual chance to reach the extreme limit of human life. On the basis of previous observations on the immunology, endocrinology and cellular biology of centenarians we focused on genes that regulate immune responses and inflammation (IL-6, IL-1 cluster, IL-10), genes involved in the insulin/IGF-I signalling pathway and genes that counteract oxidative stress (PON1). On the whole, data indicate that polymorphisms of these genes likely contribute to human longevity, in accord with observations emerging from a variety of animal models, and suggest that a common core of master genes and metabolic pathways are responsible for aging and longevity across animal species. Moreover, in the concern of our plan to discover new genetic factors related to longevity, we explored the possibility to by-pass the need of an a-priori choice of candidate genes, extending the search to genes and genomic regions of still unknown function. Alu sequences may be considered as good markers of highly variable and potentially unstable loci in functionally important genomic regions. We extensively screened Alu-rich genomic sites and found a new genomic region associated with longevity.

The G/C915 polymorphism of transforming growth factor beta1 is associated with human longevity: a study in Italian centenarians

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.

Paraoxonase 1 and atherosclerosis: is the gene or the protein more important?

The oxidation of low-density lipoprotein (LDL) is centrally involved in the initiation and progression of atherosclerosis. High-density lipoprotein (HDL) paraoxonase 1 (PON1) retards the oxidation of LDL and is a major antiatherosclerotic component of HDL. The PON1 gene contains a number of functional polymorphisms in both the coding and the promoter regions, which affect either the level or the substrate specificity of PON1. Genetic case-control and prospective studies conducted to date have produced confusing results. Meta-analysis of these studies indicates no simple relationship between the PON1 polymorphisms and the presence of coronary heart disease (CHD). However, at the present moment in time, it seems that PON1 status, i.e., activity and/or concentration, is more closely related to CHD, and indeed, PON1 has shown to be an independent risk factor for CHD in a prospective study, compared to the genetic polymorphisms. PON1 levels can also be modulated by environmental\lifestyle and possibly pharmaceutical factors. Larger, better designed, preferably prospective studies are needed to determine further the association of PON1 genetic polymorphisms and status with CHD.