Innate immunity and inflammation in ageing: a key for understanding age-related diseases

Whole Blood Analysis of Phagocytosis, Apoptosis, Cytokine Production, and Leukocyte Subsets in Healthy Older Men and Women: The ZENITH Study

Few studies to date have examined age-related changes in markers of immune status in healthy older individuals. The immune status of 93 healthy individuals aged 55-70 years was assessed by two- and three-color flow cytometry and biochemical analysis. There were significant age effects (p <or=.05) on monocyte phagocytic activity and cluster of differentiation (CD) 3/human leukocyte antigen-D-related (HLA-DR) late-activated T lymphocytes (% expression). There was a significant (p <or= 0.1) Age x Sex interaction in absolute counts (x 10(9)/L) of CD3/CD8 total cytotoxic T lymphocytes (CTL), the CD4 T- helper to CD8 CTL ratio, the CD3/CD4/CD45RA naïve T helper to CD3/CD4/CD45RO memory T helper lymphocyte ratio, and interleukin (IL)-1beta (% expression) by activated monocytes. The study shows that alterations in markers of immune status occur between 55 and 70 years, and provides reference values for the lymphocyte measures in healthy men and postmenopausal women in this age group. The study further highlights the need for sex-specific reference ranges for such markers.

Inflammation, longevity, and cardiovascular diseases: role of polymorphisms of TLR4

The total burden of infection at various sites may affect the progression of atherosclerosis, the risk being modulated by host genotype. The role of lipopolysaccaride receptor TLR4 is paradigmatic. It initiates the innate immune response against gram-negative bacteria; and TLR4 polymorphisms, as ASP299GLY, suggested to attenuate receptor signaling, have been described. We demonstrated that TLR4 ASP299GLY polymorphism shows a significantly lower frequency in patients affected by myocardial infarction compared to controls, whereas centenarians show a higher frequency. Thus, people genetically predisposed to developing weak inflammatory activity, seem to have fewer chances of developing cardiovascular diseases (CVD) and, subsequently, live longer if they do not become affected by serious infectious diseases. These results are in agreement with our other data demonstrating how genetic background may exert the opposite effect with respect to inflammatory components in CVD and longevity. In the present report, to validate this hypothesis, the levels of interleukin (IL)-6, a pro-inflammatory cytokine involved in atherosclerosis and longevity, were determined by an enzyme-linked immuno-sorbent assay (ELISA) in supernatants from a whole blood assay after stimulation with subliminal doses of lipopolysaccaride (LPS) from Escherichia coli (E. coli). The samples, genotyped for the ASP299GLY polymorphism, were challenged with LPS for 4, 24, and 48 h. What we found was that Il-6 values were significantly lower in carriers bearing TLR4 mutation. Therefore, the pathogen burden, by interacting with host genotype, determines the type and intensity of the immune-inflammatory responses accountable for pro-inflammatory status, CVD, and unsuccessful aging. On the other hand, our present data seem to explain the inconclusive results obtained in case-control studies taking into account the role of functional IL-6 polymorphisms in successful and unsuccessful aging. In fact, IL6 levels seem to depend, in addition, on IL-6 polymorphisms and on innate immunity gene polymorphisms as well.

Genetic polymorphisms of inflammatory cytokines and myocardial infarction in the elderly

Cardiovascular diseases (CVD), such as myocardial infarction (MI), are major causes of disability and mortality in the elderly. The increasing burden of CVD in ageing industrialized populations requires intensive research in order to improve preventive and therapeutic strategies especially in old people and if possible slow the processes of cardiovascular disease generation and progression. Ageing is accompanied by an age-dependent up-regulation of the inflammatory response, due to chronic antigenic stress stimulation, which potentially triggers the onset of inflammatory diseases, especially CVD. However, the exact mechanisms are still poorly understood. Since CVD are caused by interactions between genetic and environmental factors, a possible approach to their prevention is to identify the potential genetic component of inflammatory cardiovascular risk factors, providing the basis for personalized lifestyle modification and improved pharmacological therapy. Some common gene polymorphisms associated with high production of inflammatory molecules have been associated with atherosclerosis. Therefore, controlling inflammation might play a protective role against CVD, especially in ageing. Although a large number of studies of pro- and anti-inflammatory gene variants in association with CVD and MI exists, the emerging data are quite conflicting and do not provide definitive evidence for a role of these polymorphisms in the pathogenesis of MI. In this paper we review the evidence for a possible role of genetic polymorphisms of the most important inflammatory cytokines (IL-6, TNF-alpha, IL-10) and immune receptors (CD14 receptor and TLR-4) in modulating the incidence or the prognosis of MI, with a special focus in ageing population.

Association between the HLA-A2 allele and Alzheimer disease

In the elderly, the most common cause of dementia is Alzheimer disease (AD), which is responsible for the age-related progressive neurodegenerative inflammatory condition mediated by the disease. It has been seen that several genetic and environmental factors are involved in AD onset. Epidemiologic data suggest that some genetic determinants of AD might reside in those polymorphisms that regulate immune inflammatory responses, such as the major histocompatibility complex (MHC). Therefore, several MHC polymorphisms have been in the spotlight of a large number of AD association studies. A possible association of HLA-A2 allele with increased susceptibility to AD has been the subject of debate for more than 20 years, even if the results of these studies, in the various populations, are discordant. Thus, to gain insight in this matter, the authors have studied the HLA-A2 allele for a possible association with sporadic AD in a homogeneous population of Italian patients. For this reason, the distribution of HLA-A2 allele in patients with sporadic AD and controls was analyzed by PCR-SSP assay. The results demonstrated a significant difference in the frequency of HLA-A2 allele between patients with sporadic AD and controls (46% versus 38%). Thus, these data confirm a positive role of HLA-A2 allele in the risk of developing AD. However, some of the observed discrepancies may result from clinical or genetic heterogeneity of the populations under study or methodologic biases. Besides, whenever external agents such as viruses play a role, these might different in the various populations leading to various associations. However, it has to be taken into account that there are many molecular HLA-A2 subtypes with different frequencies in various populations. Therefore, further studies should include molecular typing of HLA-A2 subtypes.

Opposite Role of Pro-Inflammatory Alleles in Acute Myocardial Infarction and Longevity: Results of Studies Performed in a Sicilian Population

The major trait characterizing offspring in centenarians is a reduction in the prevalence of cardiovascular disease. Because a pro-inflammatory genotype seems to contribute significantly to the risk of coronary heart disease, alleles associated with disease susceptibility would not be included in the genetic background favoring longevity, as suggested by our previous studies on inflammatory cytokines. To confirm whether genotypes of inflammatory molecules play an opposite role in atherosclerosis and longevity, we are studying the role of other proinflammatory alleles, such as pyrin and CCR5, in acute myocardial infarction and longevity. The results support the hypothesis that the genetic background favoring cardiovascular diseases is detrimental to longevity. In addition, they suggest that the centenarian genetic background may be useful for investigating genetic key components of age-associated diseases that are characterized by a multifactorial etiology.

Immunological and immunogenetic markers in sporadic Alzheimer's disease

BACKGROUND

Common polymorphisms of genes controlling inflammation-modulating cytokines and acute-phase proteins which play important roles in the pathogenesis of Alzheimer's disease (AD) have been shown to be associated with AD.

AIMS

The immunological and immunogenetic markers potentially useful for the AD risk evaluation and diagnosis are briefly reviewed.

CONCLUSION

The state-of-the-art of immunological and immunogenetic markers of AD indicates that new tools and strategies are necessary to identify gene products useful as diagnostic tools.

Systemic inflammatory response in erderly patients following hernioplastical operation

The number of old and oldest old patients undergoing surgery of varying severity is increasing. Ageing is a process that changes the performances of most physiological systems and increases susceptibility to diseases and death; accordingly, host responses to surgical stress are altered with ageing and the occurrence of age-related increase in susceptibility to post-operative complications has been claimed. Twenty-four male patients undergoing Lichtenstein (LH) hernioplasty for unilateral inguinal hernia were included in this study and divided in two groups (Young and Old respectively), according to their age. As expression of the acute phase response, we measured changes in concentration of pro-inflammatory cytokines Tumor necrosis factor-α and Interleukin-1β, leukocytes, acute phase proteins C-reactive protein and α 1-antitrypsin. Elderly humans showed prolonged and strong inflammatory activity compared to younger subjects in response to surgical stress, indicating that the acute-phase response to surgical stress of elderly humans varies from that of the young, showing initial hyperactivity and a delayed termination of the response. Thus, the acute phase response to surgical stress is higher in old subjects, but the clinical significance of this remains unclear. It is not known whether a causal relationship exists between this stronger acute phase response and the increases in susceptibility to post-operative complications observed in aged patients.

Tumor necrosis factor-alpha -308A/G polymorphism is associated with age at onset of Alzheimer's disease

Pro-inflammatory cytokines and acute-phase proteins play an important role in Alzheimer's disease (AD) neurodegeneration, and common polymorphisms of genes controlling their production have been shown to be associated with AD. Tumor necrosis factor (TNF)-alpha is an inflammatory cytokine involved in the local immune response occurring in the central nervous system of AD patients. Genetic variation could contribute to the risk of developing AD or influence the age at the onset of the disease. We genotyped 222 patients (152 women, 70 men; age range 60-87) and 240 non-demented age-matched healthy controls for TNF-alpha -308 G/A single nucleotide polymorphism (SNP). No significant differences were observed in genotyped frequencies between patients and controls, whereas carriers of -308A showed a significantly lower mean age at onset than non-carriers of this allele. This difference was more evident taking into account ApolipoproteinE (ApoE) status since the lowest age at onset was observed in patients carrying the -308ATNF+/APOE4+ genotypes. In conclusion, our data support previous suggestions that, at least in Caucasians, the TNF gene is a disease modifier gene in patients in which AD is rising, bringing to light the importance of genetic variation at the pro-inflammatory components in the progression of AD.

Biology of Longevity: Role of the Innate Immune System

Genetic factors play a relevant role in the attainment of longevity because they are involved in cell maintenance systems, including the immune system. In fact, longevity may be correlated with optimal functioning of clonotypic and natural immunity. The aging of the immune system, known as immunosenescence, is the consequence of the continuous attrition caused by chronic antigenic overload. The antigenic load results in the progressive generation of inflammatory responses involved in age-related diseases. Most of the parameters influencing immunosenescence appear to be under genetic control, and immunosenescence fits with the basic assumptions of evolutionary theories of aging, such as antagonistic pleiotropy. In fact, by neutralizing infectious agents the immune system plays a beneficial role until reproduction and parenting. However, by determining chronic inflammation, it can be detrimental later in life, a period largely unforeseen by evolution. In particular, the data coming from the long-lived male population under study show that genetic polymorphisms responsible for a low inflammatory response might result in an increased chance of long lifespan in an environment with a reduced pathogen burden. Such a modern and healthy environment also permits a lower grade of survivable atherogenic inflammatory response.

Oxidative stress in leukocytes from young prematurely aging mice is reversed by supplementation with biscuits rich in antioxidants

Aging is associated with a progressive dysregulation of immune responses as a result of increased oxidative stress. Therefore, we have assessed the oxidative stress status of peritoneal leukocytes from young prematurely aging mice (PAM) as compared with non-prematurely aging mice (NPAM), as well as the effects on this oxidative stress of a dietary supplementation with biscuits rich in antioxidants (vitamin C, vitamin E, beta-carotenes, zinc and selenium). We found that, in the peritoneal leukocytes, the levels of several parameters of oxidation such as extracellular superoxide anion (O(2)(-)), Prostaglandin E(2) (PGE(2)), nitric oxide, oxidized glutathione (GSSG) and lipid peroxidation (malondialdehyde, MDA) were higher in PAM as compared with NPAM, whereas the antioxidant defences such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activities, as well as reduced glutathione (GSH) levels, were decreased. Consequently, young PAM showed an oxidative stress in their leukocytes, which is characteristic of mice of an older chronological age. Antioxidant diet supplementation was able to restore redox homeostasis, increasing the antioxidant and decreasing the oxidant levels. Accordingly, supplementation with adequate levels of antioxidants, from an early age, could be useful to preserve health, especially in prematurely aging populations.

Role of the pyrin M694V (A2080G) allele in acute myocardial infarction and longevity: a study in the Sicilian population

A proinflammatory genotype seems to contribute significantly to the risk of developing coronary heart disease (CHD). Conversely, the susceptibility alleles to inflammatory disease should be infrequent in the genetic background favoring longevity. In fact, in a modern environment, attainment of longevity is facilitated by an anti-inflammatory status. To evaluate whether inflammatory alleles of pyrin, the gene responsible for familial Mediterranean fever (FMF) may play an opposite role in CHD and in longevity, we examined three FMF-associated mutations, M694V (A2080G), M694I (G2082A), and V726A (T2177C), encoded by the FMF gene (MEFV) in 121 patients affected by acute myocardial infarction (AMI), in 68 centenarians, and in 196 age-matched controls from Sicily. None of the Sicilian subjects studied carried the V726A and the M694I FMF-related mutations. The proinflammatory M694V (A2080G) mutation was the only one we found, which was over-represented significantly in CHD patients and under-represented in oldest old, and intermediate values were in healthy, young controls. After adjustment for well-recognized AMI risk factors, the M694V allele still predicted a significant risk to develop AMI. So, according to these results, we suggest that carrying the proinflammatory M694V pyrin allele may increase the risk to develop AMI. Conversely, the wild-type pyrin genotype may predispose to a greater chance to live longer in a modern environment with reduced pathogen load and improved control of severe infections by antibiotics. All these data indicate a strong relationship among inflammation, genetics, CHD, and longevity.

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.

Glutathione S -transferase T1 polymorphisms are associated with outcome in colorectal cancer

Colorectal cancer (CRC) remains a significant cause of mortality accounting for approximately 10% of all deaths from malignancy in the western world. Polymorphism in the glutathione S-transferase GSTT1 gene has been associated with CRC risk in some but not all studies. In this study, we examined associations between GSTT1 genotypes and CRC risk, and prognosis in 361 cases and 881 unrelated controls. GSTT1 null was associated with a small but significant increase in risk (P = 0.0006, odds ratio (OR) = 1.65, 95% confidence interval (CI) = 1.22-2.24). GSTT1 null was also associated with a significantly younger age at diagnosis (mean 65.2 years) compared with GSTT1 A (mean 67.6 years, P = 0.031). There were no significant associations between GSTT1 genotypes and clinical factors (e.g. Dukes stage, differentiation and tumour node metastasis classification) in the total case group. However, following stratification by age (<70 versus > or =70 years at diagnosis), in the patients diagnosed <70 years of age, GSTT1 null was more common in Dukes grade A/B tumours (P = 0.046), stage T1/T2 tumours (P = 0.053) and those with a pushing margin (P = 0.066). We also identified associations between GSTT1 null and increased prevalence of host lymphocyte response, particularly in the younger patients (P = 0.036). Furthermore, GSTT1 null was associated with improved survival in younger patients (P = 0.017, hazards ratio (HR) = 0.52, 95% CI = 0.31-0.89) but poorer survival in older patients (P = 0.017, HR = 1.89, 95% CI = 1.12-3.20). We proposed a model based on the dual functionality of GSTT1 to explain these contrasting results. We suggest that the null genotype is associated with improved immune response in younger patients, but poorer detoxification in older patients. These findings may also provide an explanation for the contrasting finding of other studies on the role of this gene in CRC.