Lack of association between human longevity and polymorphisms of IL-1 cluster, IL-6, IL-10 and TNF-alpha genes in Finnish nonagenarians

Association of TGFβ1 codon 10 (T>C) and IL-10 (G>C) cytokine gene polymorphisms with longevity in a cohort of Italian population

Longevity is a complex process controlled by both environmental and genetic factors. We evaluated the association of four cytokine gene polymorphisms with longevity in an Italian cohort. A sample of 1019 subjects aged 10 to 100 and belonging to the North-Italian population was genotyped for IL-6 (G>C, rs1800796), IL-10-1082 (G>A, rs1800896), TNF-α-308 (G>A, rs1800629), and TGFβ1 codon 10 (T>C, rs1800471) gene polymorphisms. The association between cytokine gene polymorphisms and longevity was evaluated by dividing the sample into four age groups: 10 to 24, 25 to 49, 50 to 85, and 86 to 100. We observed a significant decrease in the frequency of IL-10 A allele in the 25 to 49 (P = 1.1 × 10^-3 ), 50 to 85 (P < 1 × 10^-4 ), and 86 to 100 (P = 2 × 10^-3 ) age groups compared to that in the youngest age group. Similarly, we found a significant decrease (P < 1 × 10^-4 ) in the frequency of TGFβ1 C allele in the 50 to 85 and 86 to 100 age groups compared to that in the 10 to 24 and 25 to 49 age groups. Previously, high levels of TGFβ1 were detected in elderly subjects, suggesting that this cytokine could counterbalance the harmful effects of inflammation. Similarly, IL-10 has strong anti-inflammatory properties and can inhibit the production of proinflammatory cytokines. In the literature, the lowest levels of functional cytokines were found to be associated with TGFβ1 (T>C) and IL-10 (G>A) gene polymorphisms, with consequent increase in the duration of inflammation and cancer risk. For these reasons, it is plausible to observe low rates of these mutations in elderly subjects, as found in our study.

Review and meta-analysis of genetic polymorphisms associated with exceptional human longevity

BACKGROUND

Many factors contribute to exceptional longevity, with genetics playing a significant role. However, to date, genetic studies examining exceptional longevity have been inconclusive. This comprehensive review seeks to determine the genetic variants associated with exceptional longevity by undertaking meta-analyses.

METHODS

Meta-analyses of genetic polymorphisms previously associated with exceptional longevity (85+) were undertaken. For each variant, meta-analyses were performed if there were data from at least three independent studies available, including two unpublished additional cohorts.

RESULTS

Five polymorphisms, ACE rs4340, APOE ε2/3/4, FOXO3A rs2802292, KLOTHO KL-VS and IL6 rs1800795 were significantly associated with exceptional longevity, with the pooled effect sizes (odds ratios) ranging from 0.42 (APOE ε4) to 1.45 (FOXO3A males).

CONCLUSION

In general, the observed modest effect sizes of the significant variants suggest many genes of small influence play a role in exceptional longevity, which is consistent with results for other polygenic traits. Our results also suggest that genes related to cardiovascular health may be implicated in exceptional longevity. Future studies should examine the roles of gender and ethnicity and carefully consider study design, including the selection of appropriate controls.

Age and Age-Related Diseases: Role of Inflammation Triggers and Cytokines

Cytokine dysregulation is believed to play a key role in the remodeling of the immune system at older age, with evidence pointing to an inability to fine-control systemic inflammation, which seems to be a marker of unsuccessful aging. This reshaping of cytokine expression pattern, with a progressive tendency toward a pro-inflammatory phenotype has been called "inflamm-aging." Despite research there is no clear understanding about the causes of "inflamm-aging" that underpin most major age-related diseases, including atherosclerosis, diabetes, Alzheimer's disease, rheumatoid arthritis, cancer, and aging itself. While inflammation is part of the normal repair response for healing, and essential in keeping us safe from bacterial and viral infections and noxious environmental agents, not all inflammation is good. When inflammation becomes prolonged and persists, it can become damaging and destructive. Several common molecular pathways have been identified that are associated with both aging and low-grade inflammation. The age-related change in redox balance, the increase in age-related senescent cells, the senescence-associated secretory phenotype (SASP) and the decline in effective autophagy that can trigger the inflammasome, suggest that it may be possible to delay age-related diseases and aging itself by suppressing pro-inflammatory molecular mechanisms or improving the timely resolution of inflammation. Conversely there may be learning from molecular or genetic pathways from long-lived cohorts who exemplify good quality aging. Here, we will discuss some of the current ideas and highlight molecular pathways that appear to contribute to the immune imbalance and the cytokine dysregulation, which is associated with "inflammageing" or parainflammation. Evidence of these findings will be drawn from research in cardiovascular disease, cancer, neurological inflammation and rheumatoid arthritis.

Effects of age on systemic inflamatory response syndrome and results of coronary bypass surgery

Background

Coronary artery bypass (CAB) surgery triggerssystemic inflammatory response syndrome (SIRS) via severalmechanisms. Moreover, age is directly correlated with SIRS.We evaluated the effect of age on SIRS and postoperativeoutcome after CAB surgery.

Methods

We retrospectively reviewed the records of 229 patients who had undergone CAB surgery. The patients were divided into three groups according to age: group 1, < 40 years (n = 61); group 2, 40–75 years (n = 83); and group 3, > 75 years old (n = 85). Pre- and peri-operative data were assessed in all patients. SIRS was diagnosed according to the criteria established by Boehme.

Results

The average pre-operative EuroSCORE value in group 3 was higher than in the other groups and body surface areas were significantly lower in group 3 than in the other groups (p < 0.05). The postoperative SIRS rates were 68.9% in group 1, 84.3% in group 2 and 91.8% in group 3 (group 1 vs group 3; p < 0.05). Mortality rates were not significantly different between the groups (p > 0.05). The predictive factors for SIRS were age, EuroSCORE rate, on-pump CAB surgery and intra-aortic balloon pump use.

Conclusion

Age was an important risk factor for SIRS during the postoperative period after CAB.

Association of longevity with TNF-α G308A and IL-6 G174C polymorphic inflammatory biomarkers in Caucasians: a meta-analysis

BACKGROUND

Mutations in genes encoding tumor necrosis factor (TNF)-α and interleukin (IL)-6 were previously shown to affect mortality. Single nucleotide polymorphisms (SNPs) in the functional promoter regions of TNF-α (G308A) and IL-6 (G174C) are among the most widely studied.

OBJECTIVES

To determine whether TNF-α G308A and IL-6 G174C SNPs confer susceptibility to longevity, we performed a meta-analysis to comprehensively estimate the association between these SNPs and longevity in long-lived individuals (LLI, aged ≥ 80 years).

MATERIALS AND METHODS

Studies addressing the role of TNF-α and IL-6 SNPs in longevity were identified from the PubMed database. Pooled ORs with 95 % confidence intervals (CIs) were used to assess the association between SNPs and longevity.

RESULTS

The meta-analysis was based on four studies of TNF-α G308A and nine of IL-6 G174C, covering a total of 2945 LLI individuals and 2992 controls. Overall, no significantly increased risks were observed for G308A [A vs. G (additive model): OR = 0.98, 95 % CI = 0.79-1.22, p = 0.852; AA + AG vs. GG (dominant model): OR = 0.97, 95 % CI = 0.75-1.24, p = 0.791] or for G174C [C vs. G (additive model): OR = 1.07, 95 % CI = 0.94-1.22, p = 0.293; CC + CG vs. GG (dominant model): OR = 1.09, 95 % CI = 0.93-1.28, p = 0.299]. There was no change in the significance when a cutoff age of ≥ 90 years was introduced.

CONCLUSIONS

We found no evidence that the TNF-α G308A and IL-6 G174C SNPs affected the probability of reaching an advanced age in Caucasians, and that they have little effect on delaying the onset and progression of age-related diseases, but this does not rule out the possibility of population-specific effects caused by different genes and/or environmental factors and their interactions.

Interleukin 6 gene polymorphism -174 is associated with the diffuse type gastric carcinoma

The aim of this study was to assess the significance of the interleukin 6 gene polymorphism -174 in gastric cancer risk. The interleukin 6 -174 G/C (rs1800795) gene polymorphisms was analyzed in gastric cancer, peptic ulcer, and nonulcer dyspepsia patients and in healthy control subjects and the data were correlated with the histopathological features of the patients' biopsies. The interleukin 6 -174 GG and GC genotypes have been previously associated with high interleukin 6 serum levels. We discovered that the interleukin 6 -174 GG and GC genotypes are associated with an increased risk of the diffuse histologic subtype of gastric carcinomas (OR: 6.809, P = 0.034), but absent in the intestinal type carcinomas (OR: 1.109, P = 0.908). No significant associations with peptic ulcer, gastric atrophy, or intestinal metaplasia were seen. Our results demonstrate that the interleukin 6 -174 GG and GC genotypes increase the risk of the diffuse type gastric carcinoma, but not the intestinal type gastric carcinoma or its precursor conditions, including atrophy or intestinal metaplasia. Thus, interleukin 6 seems to be an important carcinogenetic factor in the diffuse type gastric adenocarcinoma and its carcinogenetic effect could be noninflammatory.

Evidence from case-control and longitudinal studies supports associations of genetic variation in APOE, CETP, and IL6 with human longevity

In this study, we investigated 102 single-nucleotide polymorphisms (SNPs) covering the common genetic variation in 16 genes recurrently regarded as candidates for human longevity: APOE; ACE; CETP; HFE; IL6; IL6R; MTHFR; TGFB1; APOA4; APOC3; SIRTs 1, 3, 6; and HSPAs 1A, 1L, 14. In a case-control study of 1,089 oldest-old (ages 92-93) and 736 middle-aged Danes, the minor allele frequency (MAF) of rs769449 (APOE) was significantly decreased in the oldest-old, while the MAF of rs9923854 (CETP) was significantly enriched. These effects were supported when investigating 1,613 oldest-old (ages 95-110) and 1,104 middle-aged Germans. rs769449 was in modest linkage equilibrium (R (2)=0.55) with rs429358 of the APOE-ε4 haplotype and adjusting for rs429358 eliminated the association of rs769449, indicating that the association likely reflects the well-known effect of rs429358. Gene-based analysis confirmed the effects of variation in APOE and CETP and furthermore pointed to HSPA14 as a longevity gene. In a longitudinal study with 11 years of follow-up on survival in the oldest-old Danes, only one SNP, rs2069827 (IL6), was borderline significantly associated with survival from age 92 (P-corrected=0.064). This advantageous effect of the minor allele was supported when investigating a Dutch longitudinal cohort (N=563) of oldest-old (age 85+). Since rs2069827 was located in a putative transcription factor binding site, quantitative RNA expression studies were conducted. However, no difference in IL6 expression was observed between rs2069827 genotype groups. In conclusion, we here support and expand the evidence suggesting that genetic variation in APOE, CETP, and IL6, and possible HSPA14, is associated with human longevity.

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.

Age- and gender-specific epistasis between ADA and TNF-α influences human life-expectancy

Aging is a complex phenotype with multiple determinants but a strong genetic component significantly impacts on survival to extreme ages. The dysregulation of immune responses occurring with increasing age is believed to contribute to human morbidity and mortality. Conversely, some genetic determinants of successful aging might reside in those polymorphisms for the immune system genes regulating immune responses. Here we examined the main effects of single loci and multi-locus interactions to test the hypothesis that the adenosine deaminase (ADA) and tumor necrosis factor alpha (TNF-α) genes may influence human life-expectancy. ADA (22G>A, rs73598374) and TNF-α (-308G>A, rs1800629; -238G>A, rs361525) functional SNPs have been determined for 1071 unrelated healthy individuals from Central Italy (18-106 years old) divided into three gender-specific age classes defined according to demographic information and accounting for the different survivals between sexes: for men (women), the first class consists of individuals<66 years old (<73 years old), the second class of individuals 66-88 years old (73-91 years old), and the third class of individuals>88 years old (>91 years old). Single-locus analysis showed that only ADA 22G>A is significantly associated with human life-expectancy in males (comparison 1 (age class 2 vs. age class 1), O.R. 1.943, P=0.036; comparison 2 (age class 3 vs. age class 2), O.R. 0.320, P=0.0056). Age- and gender-specific patterns of epistasis between ADA and TNF-α were found using Generalized Multifactor Dimensionality Reduction (GMDR). In comparison 1, a significant two-loci interaction occurs in females between ADA 22G>A and TNF-α -238G>A (Sign Test P=0.011). In comparison 2, both two-loci and three-loci interaction are significant associated with increased life-expectancy over 88 years in males. In conclusion, we report that a combination of functional SNPs within ADA and TNF-α genes can influence life-expectancy in a gender-specific manner and that males and females follow different pathways to attain longevity.

Immunogenetics of ageing

The ageing process is very complex. Human longevity is a multifactorial trait which is determined by genetic and environmental factors. Twin and family studies imply that up to 25% of human lifespan is heritable. The longevity gene candidates have generally fallen into the following categories: inflammatory and immune-related factors, stress response elements, mediators of glucose and lipid metabolism, components of DNA repair and cellular proliferation and mitochondrial DNA haplogroups. Because of the central role of HLA molecules in the development of protective immunity and the extraordinary degree of polymorphism of HLA genes, many studies have addressed the possible impact of these genes on human longevity. Most of the data available so far demonstrated a possible role of HLA class II specificities in human longevity but definitive evidence has remained elusive. Although the data are limited and controversial, it has been hypothesized that longevity could be associated with cytokine gene polymorphisms correlating with different levels of cytokine production, thereby modulating immune responses in health and disease. Because of the essential role of cytokines in immune responses, the regulation of cytokine gene expression and their polymorphic nature, the genetic variations of these loci with functional significance could be appropriate immunogenetic candidate markers implicated in the mechanism of successful ageing and longevity. In addition, several other genes such as Toll-like receptor genes, Cycloxygenases (COX)/Lipoxygenases (LOX), CCR5, NK receptor genes and MBL2 have been assessed as a possible biomarkers associated with ageing. This review will summarize the data on the role of these immune genes in human longevity.

'Immunogenetics of Aging': report on the activities of the 15th International HLA and Immunogenetics Working Group and 15th International HLA and Immunogenetics Workshop

'Immunogenetics of Aging' is a component that was first included in the 14th International HLA and Immunogenetics Workshop (IHIWS) and developed further within the 15th Workshop. The aim of this component was to assess the impact of human leukocyte antigen (HLA) genes, cytokine genes, and some innate immunity genes such as killer-cell immunoglobulin-like receptors (KIRs) and mannose-binding lectin 2 (MBL2) in successful aging and their contribution to the better understanding of immune dysfunction in old age. Within the 15th IHIWS new populations were included in the analysis. Additional cytokine gene polymorphisms were assessed and innate immunity genes were analyzed for possible relevance in longevity. The results showed that longevity might be associated with anti-inflammatory cytokine gene profiles, decreased frequency of interleukin-10 (IL-10) and transforming growth factor-B1 haplotypes associated with a low level of gene expression, and increased frequency of haplotypes determining a high level of expression. Extended tumor necrosis factor-A and IL-12B genotypes were also likely relevant to longevity. Data also showed that innate immunity genes are associated with susceptibility to infections in the elderly and showed that these genes might be an important genetic marker in aging. Decreased frequencies of KIR2DS5 and A1B10 haplotypes, and an increased proportion of MBL2-deficient haplotypes were found in the group with higher cytomegalovirus-specific IgG antibody levels. Together, these studies emphasize the relevance of genes regulating immune functions in maintaining human longevity and stress the importance of further clarifying their impact on successful aging.

Association of longevity with IL-10 -1082 G/A and TNF-alpha-308 G/A polymorphisms

Cytokines are crucial for the regulation of inflammation development in humans. Many studies have shown that variations in cytokine genes might play a role in determining human longevity. This study examined the changes in the gene pool relevant to the -308 G/A polymorphism in the promoter region of the proinflammatory cytokine tumour necrosis factor (TNF)-alpha gene and the -1082 G/A polymorphism in the promoter region of anti-inflammatory cytokine interleukin (IL)-10 gene with aging and survival selection occurs in the Jordanian population. IL-10 -1028 G/A and TNF-alpha-308 G/A were genotyped in 119 randomly selected elderly subjects (41 women and 78 men) with a mean age of 90.2 years and young control subjects of 118 (46 women and 72 men) with a mean age of 31.9 years. No significant differences were found in the genotype and allele frequencies of TNF-alpha gene variants between the two groups (P > 0.05) while the IL-10 genotype and allele frequencies were significantly associated with longevity in men (P < 0.05) but not in women (P < 0.05). Thus, IL-10 -1028 G/A polymorphism seems to play a role in the pathway to longevity in Jordanian men.

Commonly studied polymorphisms in inflammatory cytokine genes show only minor effects on mortality and related risk factors in nonagenarians

Systemic low-grade inflammation is consistently associated with functional status, cognitive functioning, multimorbidity, and survival in oldest olds. If inflammation is either a cause or a consequence of age-related pathology, genetic determinants of late-life survival can reside in cytokine genes polymorphisms, regulating inflammatory responses. The aim of this study was to test associations between commonly studied polymorphisms in interleukin (IL)6, IL10, IL15, and IL18, and tumor necrosis factor-alpha genes and late-life survival in a longitudinal cohort of nonagenarians: the Danish 1905 cohort. Additionally, associations were investigated between inflammatory markers and major predictors of mortality as cognitive and functional status. Modest sex-specific associations were found with survival, cognitive functioning, and handgrip strength. Evaluation of combined genotypes indicated that, in nonagenarian men, the balance of pro- and anti-inflammatory activity at IL18 and IL10 loci is protective against cognitive decline. In conclusion, in this large study with virtually complete follow-up, commonly studied polymorphisms in cytokine genes do not have a major impact on late-life survival or associated risk phenotypes.

TNFA and IL10 gene polymorphisms are not associated with periodontitis in Brazilians

IL-10 and TNF-α are cytokines that have complex and opposing roles in the inflammatory responses. G/A polymorphisms at position –1082 of IL10 and –308 of TNFA genes have been reported to influence the expression of IL-10 and TNF-α, respectively. The aim of this study was to investigate the association between the IL10 (-1082) and TNFA (- 308) gene polymorphisms with different clinical forms or severity of periodontitis in a sample of Brazilian individuals. DNA was obtained from oral swabs of 165 Brazilian individuals, which were divided into three groups: individuals with chronic periodontitis, aggressive periodontitis and individuals without clinical evidence of periodontitis. Evaluation of IL10 and TNFA polymorphisms was performed by RFLP analysis. Statistical analysis of data was performed using the χ² likelihood ratio and Fisher`s exact test. No significant differences in the genotype and allele distribution of either IL10 or TNFA were observed among individuals with different clinical forms or with different degrees of severity of periodontitis. Moreover, combined analysis of IL10 and TNFA polymorphisms did not show any association with periodontal status. As conclusion, the IL10 and TNFA gene promoter polymorphisms investigated are not associated with different clinical forms of periodontitis or with severity of the disease in the Brazilian population polymorphisms.

Implications of cytokine gene polymorphisms on the orchestration of the immune response: lessons learned from oral diseases

Over the past 10 years, a plethora of information concerning the influence of gene polymorphisms on cytokine expression has been made available in the literature. Significant contribution to this field has come from studies of oral diseases, one of the widest spread health problems in the world, affecting hundreds of millions worldwide. Here we will discuss the importance of studies of gene polymorphism towards the identification of susceptible groups or prognostic indicators of oral disease. Additionally, we will highlight the differences in data obtained from genetically diverse populations and review the application of cytokine gene polymorphisms studies in oral diseases in autoimmune processes and parasitic infections.

Inflammation and frailty measures in older people

Inflammation in patients defined as frail by Fried’s phenotypic definition may be related to sarcopenia. This study aimed to investigate inflammation in older patients across different frailty criteria. Frailty status was determined in 110 patients aged over 75 years (mean 83.9 years) according to function (dependent, intermediate, independent); Fried (three or more items of exhaustion, weight loss, slow walking speed, low handgrip strength, low physical activity) and Frailty Index (a measure of accumulated deficits). With increasing patient frailty as defined by function and by Fried phenotype, tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and C-reactive protein (CRP) increased significantly. Albumin was lowest in the frailest subjects by each definition. The greatest differences were seen between intermediate and dependent groups and between the pre-frail and frail. Adjustment for multiple covariates (age, sex, BMI category, smoking status, number of co-morbidities and number of prescribed medications) did not account for any of the observed differences in levels of inflammatory markers. The Frailty Index correlated significantly with log-transformed CRP (r= 0.221, P < 0.05), log-transformed IL-6 (r= 0.369, P < 0.01), TNF-α (r= 0.379, P < 0.01) and inversely with albumin (r=– 0.545, P < 0.01). This study provides further evidence linking inflammation and frailty in older people, an association that seems consistent across different frailty measures.

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.

Effect of interleukin-6 polymorphisms on human longevity: a systematic review and meta-analysis

Several studies have assessed changes in frequency of -174 interleukin (IL)-6 single nucleotide polymorphism (SNP) with age. If IL-6 tracks with disability and age-related diseases, then there should be reduction, in the oldest old, of the frequency of homozygous GG subjects, who produce higher IL-6 levels. However, discordant results have been obtained. To explore the relationship between this polymorphism and longevity, we analyzed individual data on long-living subjects and controls from eight case-control studies conducted in Europeans, using meta-analysis. There was no significant difference in the IL-6 genotype between the oldest old and controls (Odds Ratio [OR]=0.96; 95% C.I.: 0.77-1.20; p=0.71), but there was significant between-study heterogeneity (I2=55.5%). In a subgroup analyses when male centenarians from the three Italian studies were included, the frequency of the IL-6 -174 GG genotype was significantly lower than the other genotypes (OR=0.49; 95% C.I.: 0.31-0.80; p=0.004), with no evidence of heterogeneity (I2=0%). Our data supports a negative association between the GG genotype of IL-6 SNP and longevity in Italian centenarians, with males who carry the genotype being two times less likely to reach extreme old age compared with subjects carrying CC or CG genotypes. These findings were not replicated in other European groups suggesting a possible interaction between genetics, sex and environment in reaching longevity.

Human models of aging and longevity

BACKGROUND

The aging phenotype in humans is very heterogeneous and can be described as a complex mosaic resulting from the interaction of a variety of environmental, stochastic and genetic-epigenetic variables. Therefore, each old person must be considered as a singleton, and consequently the definition of 'aging phenotype' is very difficult.

OBJECTIVE

We discuss the phenotype of centenarians, the best example of successful aging, as well as other models exploited to study human aging and longevity, such as families enriched in long-living subjects, twins and cohorts of unrelated subjects.

METHODS

A critical review of literature available until March 2008.

CONCLUSIONS

No single model can be considered the gold standard for the study of aging and longevity, instead the combination of results obtained from different models must be considered in order to better understand these complex phenomena. We propose that a systems biology concept such as that of 'bow-tie' architecture, useful for managing information flow, could help in this demanding task.

A genetic-demographic approach reveals male-specific association between survival and tumor necrosis factor (A/G)-308 polymorphism

The (A/G)-308 polymorphism of the tumor necrosis factor alpha gene (TNF) is associated with age-related diseases, but its influence on longevity is controversial. We genotyped for this polymorphism 747 Italian volunteers (401 women and 346 men, age 19-110 years). By applying a genetic-demographic (GD) approach we found that, in men, the survival function of allele A carriers is lower than that of noncarriers at all the ages (p =.044). After defining (by exploiting again demographic information) three age classes, we found that the frequency of men carrying the A allele decreases with age (p =.019), thus confirming the GD analysis results. The same analyses gave negative results in women. Therefore, allele A has a detrimental effect on life expectancy, and this effect is specific to men. A haplotype analysis carried out in men by screening the TNFa, TNFc, and TNFe microsatellite polymorphisms (spanning about 20 kb) confirmed the association of the TNF region with life expectancy.

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.

Interleukin-1 receptor antagonist, interleukin-6, and C-reactive protein as predictors of mortality in nonagenarians: the vitality 90+ study

BACKGROUND

Inflammation plays a major role in both aging and chronic disease. Longitudinal studies in very old people can improve our understanding of these processes. We investigated blood levels of C-reactive protein (CRP), interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1ra), and their combinations as predictors of mortality in nonagenarians.

METHODS

This is a prospective population-based study including both community-dwelling and institutionalized nonagenarians enrolled in the Vitality 90+ Study. Altogether 285 persons participated in the baseline interview and gave blood. Information on chronic disease was drawn from health center registers. Data on mortality over 4 years were obtained from the Population Register Center. In Cox proportional hazards models, chronic disease and major risk factors were adjusted for.

RESULTS

Plasma levels of IL-1ra, IL-6, and CRP were higher in persons who died during the follow-up than in those who survived. When sex, education, cardiovascular disease, diabetes, cancer, history of infections, high density lipoprotein cholesterol, Mini-Mental State Examination, body mass index, smoking status, and exercise were adjusted for, only IL-1ra was a significant predictor of mortality (hazard ratio [HR] 2.12; 95% confidence interval [CI], 1.24-3.62). Persons in the upper tertiles of both CRP and IL-1ra (HR 2.72; 95% CI, 1.25-6.00), or in the upper tertile of all three markers (HR 2.34; 95% CI, 1.23-4.61), had higher mortality than those who were not in the upper tertile in any of the markers.

CONCLUSIONS

IL-1ra is a powerful prognostic marker in very old people. Our results implicate its role in the complex interaction between inflammatory markers in aging and disease.

Interleukin 6 Variable Number of Tandem Repeats (VNTR) Gene Polymorphism in Centenarians

Recent population-based studies identified the magnitude of interleukin 6 (IL6) serum levels as a marker for functional disability, and a predictor of disability and mortality among the elderly. We investigated whether there was evidence in Southern Italy of an association between the IL6 gene variable number of tandem repeats (VNTR) polymorphism and extreme longevity, and tested for the possible interaction of apolipoprotein E (APOE) alleles with the IL6 VNTR alleles. Four alleles coding for variants of four different lengths have been identified: allele A [760 base pairs (bp)], allele B (680 bp), allele C (640 bp), and allele D (610 bp). IL6 VNTR and APOE allele and genotype frequencies were studied in a total of 61 centenarians and 94 middle-aged subjects from Southern Italy. The IL6 VNTR allele B was overrepresented in the younger control group compared with centenarians (odds ratio: 0.56, 95% confidence interval: 0.35-0.88, Bonferroni p-value < 0.05). No interactions between IL6 VNTR alleles and APOE alleles on the odds ratios to reach extreme longevity were evaluated for the smallest number of subjects in centenarians and younger controls. Our findings suggested that the presence of the IL6 VNTR allele B could be detrimental for reaching extreme longevity.

Polymorphisms in cytokine genes influence long-term survival differently in elderly male and female patients

OBJECTIVES

We asked if single nucleotide polymorphisms (SNP) in inflammatory cytokine genes related to 3-year survival in ill elderly subjects and if genotypes differed between the elderly and a younger control population.

DESIGN

Prospective observational study.

SETTING

Two geriatric departments at a university hospital.

SUBJECTS

Eighty three acutely admitted geriatric patients (83 +/- 7 year, 70% women) and 207 young healthy subjects (40 +/- 1 year, 37% women) were included.

OUTCOME MEASURES

Single nucleotide polymorphisms in the genes of tumour necrosis factor (TNF)-alpha-308 G/A, interleukin (IL)-1beta-511 C/T, IL-6-174 G/C and IL-10-1082 A/G were analysed. In the geriatric patients SNP in lymphotoxin (LT)-alpha +252 G/A and serum levels of TNF-alpha, IL-6, IL-10, soluble IL-I receptor(R)II were also determined, as well as the 3-year mortality.

RESULTS

The allele distribution did not differ significantly between the elderly and the young. In the female elderly, 3-year survival was doubled (P < 0.05) in those with the high-producing genotypes of IL-6 -174 GG and TNF-alpha -308 GA compared with those with low-producing alleles. In contrast, men with high-producing LT-alpha +252 AA and IL-1beta-511 CT&TT genotypes displayed halved 3-year survival (P < 0.05) compared with those with low-producing genotypes, whereas possession of the high-producing IL-10 -1082 GG genotype favoured survival. Serum IL-10 was higher in the high-producing IL-10 genotype in females.

CONCLUSION

As high-producing IL-6 -174 genotype favoured 3-year survival in women, whereas the likewise high-producing LT-alpha +252 and IL-1beta -511 genotypes were associated with poor survival in men, we conclude that the specific genotypes, in association with gender, may act as determinants for survival in elderly patients.

14th International HLA and Immunogenetics Workshop: report on the immunogenetics of aging

The 'Immunogenetics of Aging' is a newly included component within the 14th International HLA and Immunogenetics Workshop. The aim of this component was to determine the contribution of human leukocyte antigen (HLA), cytokine genes and other major histocompatibility complex-encoded loci to successful aging and to determine an increased capacity to reach the extreme limits of life span. Two main data sets from four European populations were included in this study: unrelated healthy elderly individuals and ethnically matched young controls, and families with longevity members. Analysis was focused on HLA class I and II and cytokine gene polymorphisms. Preliminary results showed increased frequencies of DRB1*11- and DRB*16-associated haplotypes that were found to be protective for autoimmune diseases in some populations. Additionally, in families with longevity members, alleles and haplotypes positively associated with autoimmunity were not observed. Analysis of cytokine gene polymorphisms showed prevalence of anti-inflammatory profiles in healthy elderly individuals. Inheritance of extended haplotypes in families with longevity members allowed the identification of immunogenetic profiles that could be predictive for longevity. These preliminary studies indicate the relevance of genes regulating immune functions in human longevity and the importance of clarifying further their impact in successful aging.

Autoimmunity and longevity: Presence of antinuclear antibodies is not associated with the rate of inflammation or mortality in nonagenarians

There are reports demonstrating elevated levels of autoantibodies in elderly people. We now analyzed whether the strong inflammatory response associated with aging is interrelated with the production of autoantibodies, antinuclear antibodies (ANA). In a cohort of 284 nonagenarians the rate of ANA positivity was 12.3%, which is significantly (p<0.001) higher than that in the middle-aged controls (2.8%). The mortality data of this cohort was collected after a 4-year follow-up. The ANA positivity at the age of 90 did not have any effect on the rate of survival, or on the levels of serum markers of inflammation.

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.

Th1 and Th2 cytokine gene polymorphisms in two indigenous ethnic groups in Iran

Cytokines are important immunomodulatory molecules in immune responses against microorganisms and also have an important role in the setting of disorders affecting immune system. Cytokine single nucleotide polymorphisms have been extensively studied in different normal populations as well as in relation to diseases. Some of these polymorphisms (SNP) affect cytokine gene transcription and expression. The polymorphisms of cytokine genes are potentially important as genetic predictors of the disease susceptibility and clinical outcome or as a tool for anthropological studies. In this study, samples have been collected from 261 healthy individuals located in two different regions of Iran (Tehran and Yazd). The allele and genotype frequencies of Th1 and Th2 cytokines SNP including interleukin (IL)-2, IL-4, IL-6, IL-10, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma have been investigated, using the polymerase chain reaction-sequence-specific primer method. The allele and genotype frequencies in Tehran and Yazd populations were similar except for the IL-2, IL-4, IL-6 and IL-10. The IL-4 C allele, C/C -33 and T/T -1098 genotype were significantly more frequent in Tehran than in Yazd population (P = 0.04, P = 0.004 and P = 0.001, respectively). The G/A genotype of the IL-6 (nt565) and IL-10 (-1082) was significantly less frequent in Tehran than in Yazd population (P = 0.01 and P = 0.003, respectively). The GT haplotype of the IL-2 (-330, +166) was significantly less frequent in Tehran than in Yazd population (P = 0.0002). We have also compared our whole samples with the reported data from other countries showing that Iranian population have cytokine gene polymorphism profile similar to that of Caucasians, especially Italian population.

IL-6 promoter polymorphisms and quantitative traits related to the metabolic syndrome in KORA S4

Interleukin-6 (IL-6) is a pleiotropic cytokine which has been proposed as "cytokine for gerontologists" and linked to age-related metabolic disturbances such as the metabolic syndrome or type 2 diabetes. Polymorphisms located in the promoter region of IL-6 have been reported to be involved in the regulation of IL-6 transcription. This study investigates whether IL-6 promoter variants -174 G/C and -573 G/C are associated with quantitative traits related to the metabolic syndrome (International Diabetes Federation criteria) in a population of normoglycemic subjects (n=878) from the latest KORA survey (KORA S4). Genotyping was performed using MALDI-TOF MS. Besides lower height (p=0.01) the -174 CC genotype was independently associated with lower waist (p=0.002) and hip (p=0.01) circumferences in men. Furthermore, the -174 CC genotype was associated with BMI (p=0.004) when adjusted for waist and hip circumference. The present study does not suggest associations with further components of the metabolic syndrome. The association with height seems to be the central factor indicating an influence of IL-6 on growth through impaired bone metabolism. However, the complex relationships need further investigation.

Associations of the -174 G/C interleukin-6 gene promoter polymorphism with serum interleukin 6 and mortality in the elderly

Serum interleukin-6 (sIL6) is an acknowledged predictor of all-cause mortality in older age. A common G/C polymorphism has been identified at position -174 of the IL6 gene promoter (IL6-174G>C), but its associations with sIL6 and mortality are still unclear. Data from a population-based elderly cohort (n=824) were used to study the associations of baseline sIL6 with the IL6-174 C-allele (C+) carrier status and all-cause mortality at 4 years, in the presence and absence of preexisting major diseases (PMD). Analyses were adjusted for socio-demographic factors and body-mass-index. Three-hundred-eighty-eight participants (47.1%) had PMD. Compared to the bottom sIL6 quartile, mortality increased both in presence [Hazard Ratio (HR)=3.04; 95% confidence interval (CI): 1.48-6.25] and absence of PMD [HR=3.91; 95%CI: 1.42-10.72] for the third higher sIL6 quartile, but only in presence of PMD for the top sIL6 quartile [HR=2.30; 95%CI: 1.09-4.83]. In absence of PMD, C+ carrier status did not affect both sIL6 and mortality. In presence of PMD, C+ carrier status was associated with increased baseline sIL6 [odds ratio 2.01; 95%CI: 1.25-3.22, for all sIL6 quartiles above the bottom] but not with increased mortality risk. A survival advantage was even found for C+ carriers with PMD and sIL6 in the top quartile [HR=0.31, 95%CI: 0.13-0.76]. In conclusion, although associated with increased sIL6 levels in presence of major diseases, the IL6-174 C-allele does not seem to have direct detrimental effects on survival in older age.

Association of interleukin-10 promoter single nucleotide polymorphisms -819 T/C and -592 A/C with aging

Increased inflammatory activity is known to accompany aging. Single nucleotide polymorphisms of inflammatory mediator genes might therefore affect the aging process. Relation of eight SNPs (tumor necrosis factor-alpha [TNF-alpha] -1031 T/C, interleukin-10 [IL-10] -819 T/C, IL-1beta -511 C/T, IL-6 -634 C/G, IL-18 -607 A/C, transforming growth factor-beta [TGF-beta] +869 C/T, matrix metalloproteinase-1 [MMP-1] -1607 1G/2G, and MMP-3 -1171 5A/6A) with age or gender was evaluated in 500 Japanese persons (mean age: 56.7 years old, range: 19-100) by the chi-square test. There was a significant association of IL-10 -819 T/C with age (p =.0026). The association remained significant after multivariate logistic regression analysis (odds ratio for an age interval for 1 year, 1.009; 95% CI, 1.002-1.016). Furthermore, the genotype distribution of IL-10 -819 T/C was completely consistent with that of -592 A/C. These data suggest that IL-10 -819 T/C and -592 A/C may be a promising candidate for an aging-related gene in a Japanese population.

Nutrient-gene interaction in ageing and successful ageing. A single nutrient (zinc) and some target genes related to inflammatory/immune response

In this paper, we reviewed data regarding to the pivotal role played by the 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 in some age-related diseases (atherosclerosis and infections). The polymorphisms of the genes codifying these proteins are predictive on one hand in longevity, such as IL-6 -174G/C locus, on the other hand 1267 Hsp70-2A/B or TNF-alpha -308G/A polymorphisms are associated to worsening atherosclerosis or severe infections, respectively, rather than longevity. Taking into account that longevity has a strong genetic component but, at the same time, is affected by life style and environmental factors, the analysis of these polymorphisms in association to some immune parameters (NK cell cytotoxicity) and nutritional factors (zinc) is a useful tool to unravel the role played by these genetic factors in longevity and in the appearance of age-related diseases. Indeed, these polymorphisms are associated with chronic inflammation, low zinc ion bioavailability, depressed innate immune response and high gene expression of metallothioneins, which have a limited zinc release for an optimal innate immune response in ageing. Therefore, the nutrient (zinc)-gene (IL-6, TNF-alpha and Hsp70-2) interaction is pivotal to keep under control the inflammatory/immune response with subsequent longevity, indicating these genes as "robust" for "healthy ageing".

Human leukocyte antigen class I, class II, and tumor necrosis factor-alpha polymorphisms in a healthy elder Mexican Mestizo population

Background

There is strong evidence that an individual's genetic background is an important predisposing factor to longevity. In the present study we analysed the frequency of HLA class I, class II, as well as the TNF-α -308 polymorphism that may be related to an increased life span in Mexican Mestizo healthy elders.

Results

HLA typing was performed by polymerase chain reaction sequence specific oligonucleotide (PCR SSO) reverse dot blot. The TNF-α -308 polymorphism was assessed by PCR restriction fragment length polymorphism. A significant increased frequency of HLA-DRB1*11 was found in elderly women whereas this allele was not present in elderly males. The TNF2 allele was also increased in the elder group when compared to young controls. The frequencies of the remaining alleles tested were not statistically different among groups.

Conclusion

These data suggest an ethnicity independent tendency of HLA-DRB1*11 in elder females to increase life span and a possible role of the TNF2 allele with the successful remodelling of senescent immune system.

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.

Investigation of genes coding for inflammatory components in Parkinson's disease

Several findings obtained recently indicate that inflammation may contribute to the pathogenesis in Parkinson's disease (PD). Genetic variants of genes coding for components involved in immune reactions in the brain might therefore influence the risk of developing PD or the age of disease onset. Five single nucleotide polymorphisms (SNPs) in the genes coding for interferon-gamma (IFN-gamma; T874A in intron 1), interferon-gamma receptor 2 (IFN-gamma R2; Gln64Arg), interleukin-10 (IL-10; G1082A in the promoter region), platelet-activating factor acetylhydrolase (PAF-AH; Val379Ala), and intercellular adhesion molecule 1 (ICAM-1; Lys469Glu) were genotyped, using pyrosequencing, in 265 patients with PD and 308 controls. None of the investigated SNPs was found to be associated with PD; however, the G1082A polymorphism in the IL-10 gene promoter was found to be related to the age of disease onset. Linear regression showed a significantly earlier onset with more A-alleles (P = 0.0095; after Bonferroni correction, P = 0.048), resulting in a 5-year delayed age of onset of the disease for individuals having two G-alleles compared with individuals having two A-alleles. The results indicate that the IL-10 G1082A SNP could possibly be related to the age of onset of PD.

Genotypes and haplotypes in the IL-1 gene cluster: analysis of two genetically and diagnostically distinct groups of Alzheimer patients

Increased risk of Alzheimer's disease (AD) has been associated with polymorphisms in the IL-1 gene cluster, and in particular with the IL-1alpha-889 T/T genotype. However, this association is still unclear, and needs further investigation. In order to clarify the role of these polymorphisms in the complex pathogenesis of AD we examined genotype and haplotype frequencies of the two C-to-T SNPs at position -889 and -551 in the IL-1alpha and IL-1beta genes, respectively, and of the 86 bp VNTR intron-2 polymorphisms in the IL-1Ra gene. The analysis was performed in two genetically and diagnostically distinct groups of sporadic AD from Italy and the USA. In the Italian group a significant association between the IL-1alpha-889 T/T genotype and AD (OR=3.022, 95% CI: 1.001-9.119) was found, whereas no difference was found in the group from the USA. Results were also compared with previously published studies that analyzed the same IL-1 polymorphisms in AD. In both groups, the analysis of the estimated haplotypes shows that AD patients and controls who carry the IL-1beta-511 C allele, were also more frequently carriers of the IL-1Ra 1 allele (haplotypes -C-1). The total frequency of the two -C-1 haplotypes (C-C-1 plus T-C-1) was about one half of the total frequency of the eight estimated haplotypes. This was confirmed by significant linkage disequilibrium between these two loci in both the Italian and USA groups. In the Italian group a weak association of the T-C-2 haplotype with the disease (OR=1.648, 95% CI: 1.519-1.788) was also found, whereas in the USA group no difference was found. Although ours and other published data on different samples of Caucasian and non-Caucasian AD show a great heterogeneity in the frequencies of the IL-1alpha-889, the IL-1beta-511 and the IL-1Ra VNTR gene polymorphisms, we confirm the role of the IL-1alpha-889 T/T genotype as a risk factor for sporadic AD, and show the presence of an allelic association between IL-1beta C and IL-1Ra 1 alleles in both the Italian and the USA groups, confirmed by the presence of significant levels of linkage disequilibrium between these two loci.

Interleukin-6 −174G/C polymorphism and longevity: a follow-up study

Increased rate of inflammation has been observed to be associated with aging. This is manifested, e.g. as increased blood levels of proinflammatory cytokines, such as interleukin-6 (IL-6). The production of IL-6 is, at least partially, genetically determined the single nucleotide polymorphism (SNP) at the promoter (-174G/C) being decisive. Consequently, some studies have demonstrated that the -174G/C genotype frequencies are different in very old persons as compared to younger ones. However, the results published this far have been conflicting. One of the main confounding factors in these kind of case/control association studies is the undetected difference in the population structure. To avoid this, we now have collected the mortality data of our cohort of 285 nonagenarians (representing mortality between 90 and 95 years of age) and correlated these to the IL-6 genotype. The frequency of -174 allele G was clearly higher in the survivors (n = 114) than in the non-survivors (n = 171).

Interaction of polymorphisms in the genes encoding interleukin-6 and estrogen receptor beta on the susceptibility to Parkinson's disease

The multifunctional cytokine interleukin-6 (IL-6) is involved in inflammatory processes in the central nervous system and increased levels of IL-6 have been found in patients with Parkinson's disease (PD). It is known that estrogen inhibits the production of IL-6, via action on estrogen receptors, thereby pointing to an important influence of estrogen on IL-6. In a previous study, we reported an association between a G/A single nucleotide polymorphism (SNP) at position 1730 in the gene coding for estrogen receptor beta (ERbeta) and age of onset of PD. To investigate the influence of a G/C SNP at position 174 in the promoter of the IL-6 gene, and the possible interaction of this SNP and the ERbeta G-1730A SNP on the risk for PD, the G-174C SNP was genotyped, by pyrosequencing, in 258 patients with PD and 308 controls. A significantly elevated frequency of the GG genotype of the IL-6 SNP was found in the patient group and this was most obvious among patients with an early age of onset (</=50 years) of PD. When the GG genotypes of the IL-6 and ERbeta SNPs were combined, the combination was much more robustly associated with PD, and especially with PD with an early age of onset, than respective GG genotype when analyzed separately. Our results indicate that the G-174C SNP in the IL-6 promoter may influence the risk for developing PD, particularly regarding early age of onset PD, and that the effect is modified by interaction of the G-1730A SNP in the ERbeta gene.

The Tumor Necrosis Factor Alpha −308G>A Polymorphism Is Associated with Dementia in the Oldest Old

OBJECTIVES

To test the hypothesis that the tumor necrosis factor (TNF) -308 G>A promoter gene polymorphism is a risk factor in age-related dementia and longevity.

DESIGN

A cross-sectional and a longitudinal study.

SETTING

A population-based sample of Danish centenarians.

PARTICIPANTS

One hundred-year-old Danes (n=122) from "The Longitudinal Study of Danish Centenarians." Octogenarians (n=174) and healthy volunteers aged 18 to 30 (n=47) served as reference groups.

METHODS

Whether the distribution of TNF -308 GG/GA/AA genotypes were different in centenarians than in younger age groups was investigated (Fischer exact test). Furthermore, whether the TNF -308 G>A polymorphism was associated with the prevalence of dementia (logistic regression analysis), the plasma level of TNF-alpha (analysis of variance), and mortality in the following 5 years (Cox regression analysis) within the cohort of centenarians was tested.

RESULTS

The distribution of TNF -308 genotypes was not different across the three different age groups, but the GA genotype was associated with decreased prevalence of dementia in centenarians. The few centenarians with AA carrier status had higher mortality risk and tended to show higher plasma levels of TNF-alpha, but the significance was questionable due to a low number of subjects with this genotype.

CONCLUSION

It is possible that the TNF -308 A allele is maintained during aging because subjects who are heterozygous for this polymorphism possess the optimal inflammatory response with regard to protection against age-related neurodegeneration.

Interleukin 6 −174 G/C promoter gene polymorphism in centenarians: no evidence of association with human longevity or interaction with apolipoprotein E alleles

The C allele at position -174 in the promoter of the interleukin 6 (IL-6) gene has been associated with reduced gene expression and reduced plasma levels of IL-6. Given that IL-6 tracks with functional disability and age-related diseases, there may be attrition or reduction in the frequency of the homozygous subjects, who produce higher IL-6 serum levels, in older survivors in a population. In fact, a marked reduction of the IL-6*G/*G genotype was recently demonstrated in male though not female Italian centenarians compared with younger age groups. First aim of the present study was to investigate whether there was evidence of an association among IL-6 -174 G/C promoter polymorphism and extreme longevity in a population of 81 centenarians compared with a control group of 122 middle-aged healthy subjects (mean age: 51+/-18 SD; range: 19-73 years), from Apulia (Southern Italy). Secondly, we also tested possible interaction of apolipoprotein E (APOE) alleles with the IL-6 -174 G/C promoter polymorphism in view of our recent findings for reduced APOE epsilon4 allele in centenarians. No differences have been found in the IL-6 -174 G/C promoter allele and genotype frequencies between centenarians and controls nor was there any observed interaction with APOE alleles that are also reputed to be linked to longevity. Regional genetic differences in conjunction with differing environmental factors may explain in part previous results suggesting a role of this polymorphism in longevity.

Association between longevity and cytokine gene polymorphisms. A study in Sardinian centenarians

BACKGROUND AND AIMS

Human longevity seems to be directly correlated with optimal functioning of the immune system, suggesting that some genetic determinants of longevity reside in those polymorphisms for the immune system genes which regulate immune-inflammatory responses, in particular cytokine gene polymorphisms. The frequency of -174C single nucleotide polymorphism (SNP) in the promoter region of the interleukin (IL)-6 gene is increased in Italian male centenarians. Moreover, the frequency of -1082G SNP at the 5' flanking region of the IL-10 gene coding sequence is increased among male centenarians, and that of +874A SNP at the interferon (IFN)-gamma gene was found more frequently in female centenarians. These findings indicate that different alleles at different cytokine gene codings for pro- (IL-6, IFN-gamma) or anti-inflammatory (IL-10) cytokines may affect the individual life-span expectancy, influencing the type and intensity of immune-inflammatory responses against environmental stressors.

METHODS

In the present study, we analyzed these IL-6, IL-10 and IFN-gamma gene polymorphisms in 112 (36 male, 76 female) centenarians from the island of Sardinia, whose population shows a genetic background quite different from that of mainland Italy, as well as in 137 sixty-year-old controls from the same geographic area.

RESULTS

No significant differences were observed on analyzing IL-6, IL-10 and IFN-gamma polymorphism frequencies among centenarians and controls, either on the whole and when the data were analyzed according to gender.

CONCLUSIONS

These data indicate that gene polymorphisms of cytokines playing a major regulatory role in the inflammatory response do not affect life expectancy in the Sardinian population. Thus, cytokine/longevity associations have a population-specific component, being affected by the population-specific gene pool as well as by gene-environment interactions, behaving as survival rather than longevity genes.

Inflammatory mediators in the elderly

Ageing is accompanied by 2-4-fold increases in plasma/serum levels of inflammatory mediators such as cytokines and acute phase proteins. A wide range of factors seems to contribute to this low-grade inflammation, including an increased amount of fat tissue, decreased production of sex steroids, smoking, subclinical infections (e.g. asymptomatic bacteriuria), and chronic disorders such as cardiovascular diseases and Alzheimer's disease. Furthermore, there is some evidence that ageing is associated with a dysregulated cytokine response following stimulation. Several inflammatory mediators such as tumour necrosis factor-alpha and interleukin-6 have the potential to induce/aggravate risk factors in age-associated pathology, providing a positive feedback mechanism. Thus, it is possible that inflammatory mediators constitute a link between life style factors, infections and physiological changes in the process of ageing on the one hand and risk factors for age-associated diseases on the other. Consistent with this, inflammatory mediators are strong predictors of mortality independently of other known risk factors and co-morbidity in elderly cohorts. A direct pathogenetic role of inflammatory mediators would be highly likely if longevity was shown to be associated with cytokine polymorphisms regulating cytokine production. Several studies support indeed this hypothesis but, unfortunately, findings in this area are conflicting, which probably reflects the complexity of the effect of cytokine polymorphisms and their interaction with the lifestyle and sex.

The IL-6 −174G>C polymorphism is associated with cardiovascular diseases and mortality in 80-year-old humans

Chronic low-grade elevations in circulating levels of interleukin (IL)-6 act as a marker of subclinical cardiovascular diseases (CVD) and provide an independent predictor of increased mortality in elderly populations. The purpose of the present study was to test the hypothesis that the IL-6 -174G>C promoter polymorphism was associated with a high prevalence of CVD and acted as an independent predictor of mortality in a longitudinal study of 324 relatively healthy 80-year-old people with a history of CVD in 18% of the cases. The C allele was associated with elevated serum levels of IL-6 at baseline and the CC genotype had a high prevalence of CVD. A Cox regression model was used to explore the effect of the polymorphism on survival in the following six years. A significant interaction was found between smoking status and the polymorphism. Thus, C allele carrier status was associated with increased all-cause mortality risk in non-smokers independently of sex, body mass index, co-morbidity, and low-grade elevations in serum levels of IL-6. This effect was not detected among smokers. We conclude that the IL-6 -174G>C polymorphism was an independent predictor of all-cause mortality in octogenarians but the effect was complex and interacted with the smoking status.