Analysis of HLA-DRB1, DQA1, DQB1 haplotypes in Sardinian centenarians.

Some genetic determinants of longevity might reside in those polymorphisms for the immune system genes that regulate immune responses. Many longevity association studies focused their attention on HLA (the human MHC) polymorphisms, but discordant results have been obtained. Sardinians are a relatively isolate population and represent a suitable population for association studies. Some HLA-DR and DQ alleles form very stable haplotypes with a strong linkage disequilibrium. In a previous study on Sardinian centenarians we have suggested that HLA-DRB1 *15 allele might be marginally associated to longevity. HLA-DR,DQ haplotypes are in strong linkage disequilibrium and well conserved playing a role in the association to diseases. Hence, we have evaluated, by amplification refractory mutation system/polymerase chain reaction (ARMS-PCR) the HLADQA1 and HLA-DQB1 allele frequencies in 123 centenarians and 92 controls from Sardinia to assess whether the association to HLA-DRB1 *15 allele may be due to the other genes involved in the HLA-DR,DQ haplotypes. The frequencies of HLA-DQA1, DQB1 haplotypes were not significantly modified in centenarians. Nevertheless by evaluating the frequency of DRB1 *15 linked haplotypes, we observed a not significant increase in centenarians of HLA-DQA1 *01, DQB1 *05 and HLA-DQA1 *01,DQB1 *06 haplotypes. These data suggest that these haplotypes might have a role in determining life span expectancy and longevity.

Search for genetic factors associated with susceptibility to multiple sclerosis.

Multiple sclerosis (MS) is a cell-mediated autoimmune disease characterized by type-1 cytokine production. Environmental and individual genetic background might influence this response particularly in cytokine gene polymorphisms. We evaluated whether polymorphisms of interleukin (IL)-10, IL-12, and tumor necrosis factor (TNF)-alpha genes, which might play a role in MS pathogenesis, are associated with MS susceptibility. Genotype frequencies for all the analyzed polymorphisms were not differently distributed between cases and controls. It is reasonable to suppose that the cytokine single-nucleotide polymorphisms (SNPs) studied must be considered against a larger genetic background involving other functional SNPs of Th1 regulator elements such as IL-21 and IL-23.

Frequency of polymorphisms of signal peptide of TGF-beta1 and -1082G/A SNP at the promoter region of Il-10 gene in patients with carotid stenosis.

The role of inflammation in atherosclerosis is well recognized. We have evaluated the allele frequencies of the +869T/C and +915G/C polymorphisms (SNPs) at the TGF-beta1 gene and -1082G/A SNP at IL-10 promoter sequence, two well-known immunosuppressive and anti-inflammatory cytokines, in patients with carotid stenosis. Our data suggest a lack of association between these SNPs and the susceptibility to atherosclerosis although other reports have demonstrated this association. These results may be due to the pleiotropic effects of the cytokines and/or differences in haplotype combination that should be investigated to elucidate the role of TGF-beta1 and IL-10 polymorphisms in atherosclerosis.

Analysis of candidate genes in celiac disease: a tool to identify life-threatening associated genes?

The authors have recently reported that celiac patients show a proinflammatory cytokine genetic profile characterized by the contemporaneous presence of both the tumour necrosis factor-alpha-308A and the interferon-gamma +874T allele-positive genotypes. The same alleles are considered risk factors for aging associated disease, whereas an anti-inflammatory cytokine genotype profile might be associated with an extended life expectancy. This paper reports data on the 1249-1250InsACAA/Non-Ins transforming growth factor (TGF)-beta2, a multifunctional anti-inflammatory cytokine, polymorphism distribution in 88 celiac disease (CD) patients, 99 age- and sex-matched controls, and 28 >95-year-old healthy subjects living in western Sicily. These data demonstrate that genotype frequencies of CD patients are not different from that of age-matched and >95-year-old healthy control subjects. These data might suggest that TGF-beta2 polymorphism is not involved in the complex genotypes associated with successful or unsuccessful aging. In addition, one can speculate that the genotype profile associated with CD susceptibility might be detrimental for longevity, and studies of this CD genetic asset might point to a candidate gene for antiaging strategies.

Analysis of HLA-DQA, HLA-DQB frequencies in a group of Sardinian centenarians.

Human leukocyte antigen (HLA) alleles, regulating type and intensity of the immune response, might influence life expectancy. In previous case-control studies the authors have demonstrated that both HLA-DR and -DQ alleles are not associated with longevity in the Sardinian population. On the other hand, association studies are subjected (as part of the homogeneity of the population in terms of geographic origin) to a number of possible confounding factors. Therefore, the authors typed the HLA-DQA1 and HLA-DQB1 alleles in 24 sibs (age range 85 to 97) of 17 centenarians by PCR-SSP. Sib pair analysis showed nonsignificant differences between the observed and expected percentage of DQA* or DQB1* allele sharing. Therefore, these data strengthen the view that class II HLA genes have a marginal effect, if any, on the complex longevity trait.

Study of the association with -330T/G IL-2 in a population of centenarians from centre and south Italy.

Immune response in elderly is characterised by a progressive loss of the ability to cope environmental stressors with a characteristic remodelling of cytokine network. One of the data constantly reported in literature is the decrease of IL-2 production. An IL-2 central role in the reconstitution of T cell function in vitro is largely documented. Studies on a T-->G polymorphism at -330 nt of IL-2 gene promoter region have demonstrated that T lymphocytes from 330GG homozygous subjects are able to produce in vitro higher amount of IL-2, than -330TG heterozygous or -330TT homozygous subjects. As a genetic background conditioning the maintaining of an efficient immune response would exert positive effects on healthy ageing, we have typed for 330T/G IL-2 single nucleotide polymorphism (SNP), 168 centenarians and 214 control subjects matched for age and ancestry from Centre and South Italy to check the 330GG genotype association to longevity. The statistical analysis doesn't show a significant difference of genotypic and allelic frequencies at -330 IL-2 T/G SNP among centenarians and controls. Comparing the two cohorts of subjects by extended Mantel Haenszel procedure a marginally significant trend for an increased -330TT genotype frequency was observed. Our data seem to be paradoxical considering the role attributed to a well-conserved T cell function in the successful ageing. On the other hand, in a recent study on a sample of Irish octogenarians a similar distribution of -330T/G genotype even was observed. These data suggest that a genetic background favouring an increased IL-2 production might be detrimental for longevity. On the other hand, an increase of IL-2 and other pro-inflammatory cytokine production characterise the Alzheimer's disease serum profile. All in all our data seem to suggest that reduction of -330G allele frequency might be protective for healthy ageing limiting cell mediated inflammation implied in age associated diseases.

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.

Allele frequencies of +874T --> A single nucleotide polymorphism at the first intron of IFN-gamma gene in Alzheimer's disease patients.

BACKGROUND AND AIMS: Inflammation seems to play a role in progressive neurological degenerative diseases such as Alzheimer's disease (AD). Local inflammatory processes can in fact give rise to direct neurotoxicity, interfere with beta-amyloid expression and metabolism, and maintain chronic, intracerebral, acute-phase protein secretion, in turn favoring the formation of beta-amyloid fibrils. Accordingly, recent studies show an increased risk for AD associated with certain polymorphisms in the genes encoding some proinflammatory cytokines and acute-phase proteins. To our knowledge, no data have yet been presented on the association between AD and polymorphisms of the interferon(IFN)-gamma gene, despite the pivotal role that IFN-gamma plays in immune-mediated inflammatory responses. METHODS: Using the amplification refractory mutation system method, we evaluated the role of IFN-gamma in AD by analyzing, in 111 AD patients and 213 healthy controls, the prevalence of +874T --> A single nucleotide polymorphism (SNP), associated with different IFN-gamma production. Allele ApoE polymorphisms were assessed by the PCR-based method. RESULTS: No statistically significant differences were observed between AD patients and controls in the frequency of +874T --> A SNP, either on analyzing data as a whole or according to gender. As expected, the frequency of the well-known genetic risk factor APOE-epsilon4 allele was significantly increased in AD patients. However, analyzing the results according to the presence or absence of the APOE-epsilon4 allele, no interactions among ApoE, IFN-gamma alleles, gender or age at onset were observed. CONCLUSIONS: Our study does not support the hypothesis that IFN-gamma SNP may be a genetic risk factor for AD. Further analysis of recently described IFN-gamma polymorphisms may clarify the role, if any, of IFN-gamma alleles in AD.

Plasma cytokine profiles in patients with celiac disease and selective IgA deficiency.

Celiac disease (CD) and selective IgA deficiency (IgAD) are frequently associated, and share the same genetic background. The aim of the present study was to evaluate both Type 1 and 2 plasma cytokine levels in CD and in CD-IgAD. IL-2, TNF-alpha, IL-10, IL-4 and IL-13 plasma levels were measured both at diagnosis and after a gluten-free diet (GFD) in 32 CD patients, in 27 CD-IgAD patients and in 30 healthy controls. IFN-gamma levels were significantly higher in CD and CD-IgAD than in controls, TNF-alpha displayed significantly higher levels in CD-IgAD when compared both with controls and with CD, and IL-2 was in CD-IgAD significantly increased respect to controls. Kinetics of the Type 1 cytokine plasma levels did not show a clear relationship with the GFD in both groups of CD patients, and particularly in those with IgAD. IL-4 and IL-13, both at diagnosis and after a GFD, were not significantly different in controls and in celiac patients (with and without IgAD). IL-10, whose production is stimulated by the TNF-alpha, had significantly higher plasma levels in CD-IgAD, but not in CD patients, with a significant decrease after a GFD. CD and especially CD-IgAD patients display persistently higher pro-inflammatory cytokine levels, suggesting a persistent state of activation of pro-phlogistic signals in CD, particularly when IgAD coexists. Serial measurement of serum IL-10 may be an adjunctive evaluating criterion in the follow-up of CD-IgAD patients.

IL-10 and TNF-alpha polymorphisms and the recovery from HCV infection.

Hepatitis C virus (HCV) infection becomes chronic in about 85% of infected individuals, whereas only 15% of infected people clear spontaneously the virus. It is conceivable that the host immunogenetic background influences the course of infection in term of recovery. Thus, in this study we have evaluated the effect of functionally relevant polymorphisms at tumor necrosis factor-alpha (TNF-alpha, i.e., 2 biallelic polymorphisms at nt -863 and nt-308 of the promoter) and interleukin-10 (IL-10) loci (i.e., 1 biallelic polymorphism at nt -1082 of the promoter), on the clearance of HCV infection. To this purpose, we compared 18 Sicilian patients who had spontaneously recovered from previous HCV infection with 42 Sicilian patients with current HCV infection and 135 Sicilian healthy patients. The results demonstrate a decreased frequency of the -863CC TNF-alpha promoter genotype (involved in high production of this pro-inflammatory cytokine) and an increased frequency of the -1082GG IL-10 promoter genotype (involved in high production of this anti-inflammatory cytokine) in patients recovered from HCV infection. The evaluation of combined TNF-alpha and IL-10 genotypes revealed a significant increase of the "anti-inflammatory genotype" (low-TNF/high-IL-10 producers) in resolved HCV infection group compared with patients with persistent HCV infection. On the whole, our findings suggest that a genetically determined control of the HCV-induced inflammatory response may play a role in the resolution of HCV infection.

IL-10 and TNF-alpha polymorphisms in a sample of Sicilian patients affected by tuberculosis: implication for ageing and life span expectancy.

Human longevity seems to be directly correlated with optimal functioning of the immune system, suggesting that some genetic determinants of longevity might reside in those polymorphisms for the immune system genes that regulate immune responses, in particular cytokine gene polymorphisms. In fact, modification of cytokine network is a constant report in studies on age related modification of immune response. Moreover cytokine polymorphisms studies are indicating their involvement in the reshaping of cytokines network as an integral part of the scenario related to a successful ageing. A particular role might be attributed to the influence of cytokine polymorphisms on the efficiency of immune response against infectious diseases that have been the principal selection in oldest old. Here are reported data on the evaluation of the frequency of the functional polymorphisms at genes coding for TNF-alpha (-308G-->A) and IL-10 (-1082G-->A), analysed by ARMS-PCR, in a group of Sicilian patients affected by chronic lung tuberculosis (TBC) compared to that from a group of healthy individuals living in the same region. Data obtained demonstrated a reduction of -308GG TNF homozygous individuals in TBC affected subject group. In the same group a reduction of IL-10 -1082A/* carriers was found. Our results seem to suggest that multiple genetic traits may affect the capacity to cope with an infectious agents and this might predispose to an overt disease. Moreover these data are in agreement with previous reports suggesting that a balanced interaction among pro- and anti-inflammatory molecules it is a key point for conditioning the life span expectancy.

Allele frequencies of +874T-->A single nucleotide polymorphism at the first intron of interferon-gamma gene in a group of Italian centenarians.

Ageing is characterized by a pro-inflammatory status which could contribute to the onset of major age-related diseases such as cardiovascular diseases, neurodegeneration, osteoarthritis and osteoporosis, and diabetes. Thus, it can be hypothesized that genetic variations in pro- or anti-inflammatory cytokines might influence successful ageing and longevity. We have studied the distribution of +874T-->A interferon-gamma (IFN-gamma) polymorphisms in a large number of Italian centenarians to evaluate if the two alleles might be differently represented in people selected for longevity. DNA samples were obtained from 174 Italian centenarians (>99 years old, 142 women and 32 men) and from 248 <60-year-old control subjects (90 women and 158 men) matched for geographical distribution. Polymorphisms at +874 were identified by using amplification refractory mutational system methodology. The +874T allele was found less frequently in centenarian women than in centenarian men or in control women whereas no significant differences were observed in the distribution of the two alleles between male or female controls. Allele frequencies in centenarian men were not found significantly different from male controls. Possession of the +874A allele, known to be associated with low IFN-gamma production, significantly increases the possibility to achieve extended longevity, suggesting that the pro-inflammatory status characteristic of ageing may be detrimental for successful ageing. The datum that the allele was significantly increased in female but not male centenarians seems to strengthen the idea that gender may be a major variable in the biology of the ageing process. However, the present data add another piece of evidence to the complex puzzle of genetic and environmental factors involved in controlling life span expectancy in humans. Thus, studies on cytokine gene polymorphisms may promise to individuate a complex network of trans-interactive genes able to influence the type and strength of responses to environmental stressors and as a final result, thereby conditioning individual life expectancy.