A Comprehensive Analysis of Cytokine Network in Centenarians.

Cytokines have been investigated extensively in elderly people, with conflicting results. We performed a comprehensive analysis of the plasma levels of 62 cytokines and growth factors involved in the regulation of the immune system, in healthy centenarians, and middle-aged controls. We confirmed the previously observed increase in the levels of several pro-inflammatory cytokines, such as TNF-α and IL-6, and found that several other cytokines, directly or indirectly involved in inflammation (such as IFN-α, IL-23, CCL-5), were present at higher levels in centenarians. We did not observe any increase in the levels of anti-inflammatory cytokines, with the notable exception of the Th2-shifting cytokine IL-19. No relevant difference was observed in cytokines regulating T cell immunity. Several growth factors having a role in regulating immunity, such as G-CSF, GM-CSF, EGF, and VEGF, were upregulated in centenarians, too. Principal component analysis of the cytokine dataset showed that pro and anti-inflammatory cytokines were the variables that contributed the most to the variability of the data we observed.

Characterization of the cell growth inhibitory effects of a novel DNA-intercalating bipyridyl-thiourea-Pt(II) complex in cisplatin-sensitive and -resistant human ovarian cancer cells.

The cellular effects of a novel DNA-intercalating agent, the bipyridyl complex of platinum(II) with diphenyl thiourea, [Pt(bipy)(Ph(2)-tu)(2)]Cl(2), has been analyzed in the cisplatin (cDDP)-sensitive human ovarian carcinoma cell line, 2008, and its -resistant variant, C13* cells, in which the highest accumulation and cytotoxicity was found among six related bipyridyl thiourea complexes. We also show here that this complex causes reactive oxygen species to form and inhibits topoisomerase II activity to a greater extent in the sensitive than in the resistant line. The impairment of this enzyme led to DNA damage, as shown by the comet assay. As a consequence, cell cycle distribution has also been greatly perturbed in both lines. Morphological analysis revealed deep cellular derangement with the presence of cellular masses, together with increased membrane permeability and depolarization of the mitochondrial membrane. Some of these effects, sometimes differentially evident between the two cell lines, might also be related to the decrease of total cell magnesium content caused by this thiourea complex both in sensitive and resistant cells, though the basal content of this ion was higher in the cDDP-resistant line. Altogether these results suggest that this compound exerts its cytotoxicity by mechanisms partly mediated by the resistance phenotype. In particular, cDDP-sensitive cells were affected mostly by impairing topoisomerase II activity and by increasing membrane permeability and the formation of reactive oxygen species; conversely, mitochondrial impairment appeared to play the most important role in the action of complex F in resistant cells.

Quercetin inhibits lymphocyte activation and proliferation without inducing apoptosis in peripheral mononuclear cells.

Toxicity of chemotherapeutic drugs towards normal cells is a serious side effect of cancer treatment. Thus, finding of molecules with low toxicity for normal cells is crucial. Several natural compounds, such as flavonoid quercertin, are receiving a growing attention as "chemopreventers". Quercetin kills tumour-derived cell lines, but little is known about its effects on normal cells. Here we show that although quercetin exerts a higher apoptotic potential on leukemic cell lines than on peripheral blood mononuclear cells (PBMCs) and does not sensitize PBMCs to CD95-induced apoptosis, it is able to inhibit normal immune functions such as T cell proliferation and activation. Quercetin sensitivity is independent on cell cycle progression since it was not abrogated in serum-starved U937 cells, nor proliferating PBMCs underwent apoptosis after quercetin treatment. However, quercetin prevented PHA-induced PBMC proliferation and SEB-induced upregulation of activation markers. Our data suggest that quercetin, while incapable of inducing apoptosis in normal cells under several conditions, could interfere with effector T cell function.

Investigating T cells by polychromatic flow cytometry.

Since its development, flow cytometry gave a relevant contribution to the field of Immunology. Its unique potential to analyse multiple parameters at the single cell level allowed the identification of unknown cell subsets with specific roles in immunoregulation as well as in the pathogenesis of several diseases. More recently, with the advent of new equipments and fluorochromes, the possibility exists to analyse simultaneously a large number (up to 19) of parameters in a single cell. This strategy, defined polychromatic flow cytometry (PFC), has been widely utilised in the last years for the fine analysis of immune cell phenotypes, including antigen-specific T lymphocytes, B cell subsets, and the intracellular phosphoproteome, among others. A huge amount of data can be generated by such an approach, and their interpretation could become a very complex and time-consuming task. Protocols for performing PFC will be discussed in this chapter, together with some guidelines for data interpretation and analysis.

Resistance of mtDNA-depleted cells to apoptosis.

Cells lacking mitochondrial genome (defined as rho(0)) are useful models in studies on cancer, aging, mitochondrial diseases and apoptosis, but several of their functional aspects have been poorly characterized. Using different clones of rho(0) cells derived from the human osteosarcoma line 143B, we have tested the effects of different apoptogenic molecules such as staurosporine (STS), doxorubicin, daunomycin and quercetin, and have analyzed apoptosis, mitochondrial membrane potential (MMP), levels of oxygen free radicals, reduced glutathione (GSH) content, and expression of P-glycoprotein (P-gp). When compared to parental cells, rho(0) cells resulted much less sensitive to apoptosis. MMP was well maintained in rho(0) cells, and remained unchanged after adding apoptogenic agents, and did not change after treatment with molecules able to depolarize mitochondria such as valinomycin. After adding STS, the production of reactive oxygen species was similar in both cell types, but rho(0) cells maintained higher levels of GSH. In rho(0) cells, P-gp was strongly over-expressed both at mRNA and protein level, and its functionality was higher. The resistance to apoptosis of rho(0) cells could be not only due to an increased scavenger capacity of GSH, but also due to a selection of multidrug resistant cells that hyperexpress P-gp.

Homeostatic cytokines and expansion of regulatory T cells accompany thymic impairment in children with Down syndrome.

Down syndrome (DS), the most common chromosomal abnormality in humans, is characterized by precocious immunologic aging that results, among other things, in alterations of B and T lymphocyte subsets and natural killer cells, defective phagocytosis, and chemotaxis of polymorphonuclear leukocytes. We studied 30 children affected by DS, compared them to 29 healthy controls, and evaluated the functionality of the thymus (by measuring the amount of lymphocytes that express the signal-joint T cell receptor rearrangement excision circles [sj-TREC+]), the plasma levels of interleukin (IL)-7 and IL-15, the proliferative T cell response to these cytokines, the expression of the alpha chain of the IL-7 receptor (CD127), the extrathymic differentiation of T lymphocytes, and the presence of natural regulatory T cells (Tregs) in peripheral blood. We found that DS children had a significantly lower number of sj-TREC+ lymphocytes, the levels of which were strongly correlated with age. We found higher plasma levels of IL-7 and IL-15 than in healthy controls, and a higher proliferative T cell response to IL-15. DS children also showed a lower percentage of CD4(+) cells and profound alterations of T cell differentiation, along with increased amount of Tregs and of cells expressing markers of apoptosis. We can thus hypothesize that the precocious thymic involution occurring in DS is mirrored by a high production of IL-7 and IL-15, which is crucial for cell survival and proliferation. The complex alterations present in the periphery are likely the result of a compensatory mechanism: the overproduction of homeostatic cytokines could be a reaction to the impaired intrathymic production of T lymphocytes and/or to the expansion of Treg in the periphery, and could be required to allow the survival of T cells.

Mitochondrial alterations and tendency to apoptosis in peripheral blood cells from children with Down syndrome.

Different types of cells from subjects with Down syndrome (DS) have an increased susceptibility to cell death. We have studied apoptosis and mitochondrial (mt) membrane potential (DeltaPsi(m)) in peripheral blood mononuclear cells (PBMC) from DS children and age-matched healthy donors after in vitro treatment with apoptogenic molecules, along with mtDNA content. We found that PBMC from DS and healthy controls had a similar tendency to undergo apoptosis and a similar amount of mtDNA. However, in cells from DS subjects, mitochondria showed a higher loss of DeltaPsi(m), underlying the presence of an increasing susceptibility of these organelles to damaging agents.

Thymic output and functionality of the IL-7/IL-7 receptor system in centenarians: implications for the neolymphogenesis at the limit of human life.

During aging, the thymus undergoes a marked involution that is responsible for profound changes in the T-cell compartment. To investigate the capacity of the thymus to produce new cells at the limit of human lifespan, we analyzed some basic mechanisms responsible for the renewal and maintenance of peripheral T lymphocytes in 44 centenarians. Thymic functionality was analyzed by the quantification of cells presenting the T-cell receptor rearrangement excision circles (TREC). A new method based upon real-time PCR was used, and we found that most centenarians (84%) had undetectable levels of TREC+ cells. Six-color cytofluorimetric analysis revealed that centenarians had an extremely low number of naïve T cells; central memory and effector memory T cells were greatly increased, while terminally differentiated cells were as numerous as in young (aged 20-45) or middle-aged (aged 58-62) donors. Interleukin (IL)-7 and IL-7 receptor alpha-chain (CD127) levels were the same at all ages, as shown by ELISA, flow cytometry and real-time PCR. However, IL-7 plasma levels were higher in centenarian females than males. The presence of TREC+ cells and of very few naïve T lymphocytes suggests that in centenarians such cells could either derive from residues of thymic lymphopoietic islets, or even represent long-living lymphocytes that have not yet encountered their antigen. IL-7 could be one of the components responsible, among others, for the higher probability of reaching extreme ages typical of females.

Protective effect of acetyl-L-carnitine against oxidative stress induced by antiretroviral drugs.

Both HIV infection per se and antiretroviral drugs might contribute to oxidative stress and mitochondrial dysfunctions. In this study we assess zidovudine, stavudine and didanosine on U937 and CEM cell lines. All these drugs induced apoptosis and increased intracellular hydrogen peroxide but not superoxide anions. The addition of acetyl-l-carnitine (ALC) was able to prevent the pro-oxidant effect of the drugs tested. Supplementation with ALC, deficient in certain cohorts of HIV-infected individuals, especially on high active antiretroviral therapy regimen, has been associated with favourable effects. These data suggest that one of these effects could be a direct anti-oxidant action.

Effect of treatment interruption monitored by CD4 cell count on mitochondrial DNA content in HIV-infected patients: a prospective study.

BACKGROUND: HIV infection per se and HAART can alter mitochondrial functionality, leading to a decrease in mitochondrial DNA content. OBJECTIVE: To evaluate whether treatment interruption monitored by CD4 cell count can restore mitochondrial DNA content in peripheral blood lymphocytes. METHODS: Mitochondrial DNA content was measured in platelet-free CD4 and CD8 T cells by real-time polymerase chain reaction; flow cytometry was used to identify and quantify activated CD4 and CD8 T lymphocytes. RESULTS: The 30 patients had been treated for a mean of 107 months (range, 27-197). Median CD4 cell count at discontinuation was 702 cells/microl (range, 547-798). Median observational time from HAART discontinuation was 11.3 months (range, 4-26). Discontinuation of treatment provoked significant increases in mitochondrial DNA in CD8 T cells, which started only 6 months after therapy discontinuation [5.12 copies/cell per month from 0 to 6 months (P = 0.37) and 26.96 copies/cell per month from 6 to 12 months (P < 0.0001)]. CONCLUSIONS: This study is the first showing that mitochondrial DNA content can increase in peripheral blood lymphocytes during treatment interruption, but only after at least 6 months of interruption. Consequently, interruptions of shorter periods, whether by clinician or patient decision, are unlikely to allow restoration of mitochondrial DNA and so decrease HAART-related toxicity.

Balanced regulation of mRNA production for Fas and Fas ligand in lymphocytes from centenarians: how the immune system starts its second century.

BACKGROUND: The functionality of the immune system during aging is crucial for protection against the most common age-related diseases. Apoptosis plays a central role in the senescence of the immune system, as evidenced by the increased plasma membrane expression of a key molecule like Fas protein. We analyzed the mRNA levels of different forms of Fas (total [tFas] and membrane [mFas]) and of its ligand (FasL) in peripheral blood lymphocytes from centenarians, the best example of successful aging, who were compared with young and middle-aged donors. METHODS AND RESULTS: Using real-time polymerase chain reaction, we quantified mRNA for different forms of Fas and for FasL. In resting lymphocytes, mRNA for tFas, but not for mFas, significantly increases with age, whereas FasL mRNA significantly decreases. In vitro production of Fas/FasL mRNA after different stimuli was similar in cells from the 3 groups. Even if the percentage of Fas+ cells was higher than in the other groups, peripheral blood lymphocytes from centenarians had normal Fas-induced apoptosis, as revealed by flow cytometry. By ELISA, we observed that cells from centenarians showed normal in vitro production of the soluble form of Fas (sFas) and that plasma levels of such molecule were significantly higher in centenarians than in the other groups. CONCLUSIONS: Lymphocytes from centenarians are able to balance the production of proapoptotic (mFas and FasL) and antiapoptotic (sFas) molecules, whose proportions are likely crucial for the well-preserved immune functionality at the extreme limits of human life.

Changes in mitochondrial RNA production in cells treated with nucleoside analogues.

BACKGROUND: To investigate mitochondrial (mt) toxicity of antiretroviral drugs further, we developed a novel real-time PCR-based assay for the quantification of mtRNA. We analysed the effects of stavudine (d4T), didanosine (ddl) and zidovudine (AZT) on the production of mtRNAs in different human cell lines and compared the production with the amount of mtDNA present in the same cells. MATERIALS AND METHODS: HUT78, CEM and U937 cells were exposed to different nucleoside reverse transcriptase inhibitors (NRTIs) for 7 days. Thereafter, nucleic acids were isolated and Taqman-based real-time PCR was used to quantify mtDNA and three different mtRNAs (ND1, CYTB and ND6 gene products). RESULTS: Different amounts of mtRNAs exist in different cell lines. When mtRNA was measured in cells exposed to an NRTI, a marked decrease was observed in cells treated with d4T, but not with ddl or AZT. Changes in mtRNA production did not always correspond to modifications in mtDNA content: 1 microM d4T significantly changed mtRNA but not mtDNA content. CONCLUSIONS: d4T, but not ddl or AZT, significantly alters mtRNA quantity and quality. The method we have developed can reveal changes that are not observed by measuring mtDNA content only, and can be used for ex vivo studies on drug toxicity.

Essential requirement of reduced glutathione (GSH) for the anti-oxidant effect of the flavonoid quercetin.

We have analyzed the anti- or pro-oxidant effects of the flavonoid quercetin (QU) by evaluating, in U937 cell line, hydrogen peroxide (H(2)O(2)), superoxide anion reduced glutathione (GSH) content, mitochondrial membrane potential, DNA content, phosphatidylserine exposure on the outer face of the plasma membrane and cell viability. Polychromatic flow cytometry was used to evaluate in the same cells several functional parameters. For short periods of treatment QU exerted an anti-oxidant effect (decrease in H(2)O(2) levels), whereas for long periods it showed a pro-oxidant activity (increase in ). In these conditions, GSH content was reduced, and this correlated with a lack of anti-oxidant activity of QU, which in turn could be correlated with proapoptotic activity of this molecule. Thus, QU can exert different effects (anti-/prooxidant) depending on exposure times and oxidative balance, and in particular on stores of GSH.

Direct analysis of thymic function in children with Down's syndrome.

BACKGROUND: Down's syndrome (DS) is characterized by several immunological defects, especially regarding T cell compartment. DS is considered the best example of accelerated ageing in humans. Direct observations of the thymus have shown that in DS this organ undergoes severe histological and morphological changes. However, no data on its capacity to generate T cells are present in the literature. Here, using a new technology based upon real time PCR, we have investigated the capacity of the thymus to produce and release newly generated T lymphocytes (the so called "recent thymic emigrants", RTE) in children with DS. METHODS: We studied 8 children affected by DS, aged 2-7 years, compared with 8 age- and sex-matched healthy controls. Flow cytometry was used to determine different lymphocytes subsets. Real time PCR with the Taqman system was used to quantify the amount of RTE, i.e. peripheral blood lymphocytes that express the T cell receptor rearrangement excision circles (TREC). RESULTS: In comparison with control children, those with DS had a significant lower number of TREC+ peripheral blood cells. Moreover, in DS children but not in controls, a strong negative correlation between age and the levels of TREC+ cells was found. CONCLUSIONS: The direct measure of thymic output indicates that the impairment of the organ results in a reduced production of newly generated T cells. This observation could suggest that cytokines able to modulate thymic function, such as interleukins, could be useful to improve the functionality of the organ and to treat the immunodeficiency present in DS subjects.

MDR1 C3435T genetic polymorphism does not influence the response to antiretroviral therapy in drug-naive HIV-positive patients.

P-glycoprotein, a membrane-localized protein transporter, codified by the MDR1 gene, influences the response to pharmacological treatments, including antiretroviral drugs. MDR1 polymorphism C3435T is correlated with the functionality of the protein. We investigated the influence of this polymorphism in the reconstitution of the peripheral CD4 T cell pool in 149 drug-naive HIV-positive patients starting highly active antiretroviral therapy. The MDR1 C3435Tpolymorphism did not influence response to therapy, suggesting no disadvantages for individuals with a different genotype.

Features of 'CD4-exploders', HIV-positive patients with an optimal immune reconstitution after potent antiretroviral therapy.

OBJECTIVE: To identify crucial immunological characteristics of a group of patients, defined 'CD4-exploders', who were able to fully reconstitute their immune system after receiving highly active antiretroviral therapy (HAART). PATIENTS: Among a population of 540 HIV-positive patients treated with HAART, six individuals were identified who experienced a nadir of less than 85 x 106 CD4+ cells/l, had major opportunistic infections (four out of six), started HAART in 1996 or 1997, and showed a rapid and relevant CD4+ lymphocyte increase (mainly due to virgin cells), in some cases regardless of virological control. METHODS: Enzyme-linked immunosorbent assay for the determination of interleukin (IL)-7 plasma levels; flow cytometry to analyse surface antigens and CD127 (IL-7 receptor alpha-chain) expression; quantitative-competitive (QC) PCR for detecting cells containing T-cell receptor rearrangement excision circles (TREC); chest-computed tomography (CT) to analyse thymus volume and content. RESULTS: In 'CD4-exploders', high levels of TREC+ lymphocytes were found among CD4+ T cells, which also contained a high percentage of naive cells. However, CT revealed a dramatic depletion of intrathymic lymphoid tissue. Plasma levels of IL-7 were significantly high. Most CD4+ and CD8+ T lymphocytes expressed CD127, whose level was similar to that of healthy donors. CD127 expression on CD8+ lymphocytes was markedly higher than in HIV-positive individuals treated with the same therapy or in patients with AIDS. CONCLUSION: In 'CD4-exploders', HAART-induced reconstitution of the T-cell compartment is independent from thymus volume, and is favoured by the upregulation of the IL-7/IL-7 receptor system.

Low vitamin D status, high bone turnover, and bone fractures in centenarians.

The oldest olds, including centenarians, are increasing worldwide and, in the near future, will represent a consistent part of the population. We have studied bone status and metabolism in 104 subjects over 98 yr of age to evaluate possible interventions able to avoid fragility fractures and disability. Ninety females and 14 males not affected by any acute disease were considered. After a complete clinical assessment, blood was drawn for evaluating bone turnover markers, and performance tests together with skeletal ultrasonography (either at the phalanges or at the heel) were performed. We found that 38 subjects had sustained a total of 55 fractures throughout their lives, and 75% of these were fragility fractures. Twenty-eight fractures occurred at the proximal femur, with 14 after the age of 94 yr. Serum 25-hydroxyvitamin D was undetectable in 99 of 104 centenarians. PTH and serum C-terminal fragment of collagen type I were elevated in 64 and 90% of centenarians, respectively, with a trend toward hypocalcemia. Bone alkaline phosphatase levels were close to the upper limit. Serum IL-6 was elevated in 81% of centenarians and was positively correlated with PTH and negatively correlated with serum calcium. Serum creatinine was not correlated with PTH. Bone ultrasonography showed that most centenarians had low values, and ultrasonographic parameters were correlated with resorption markers. We conclude that the extreme decades of life are characterized by a pathophysiological sequence of events linking vitamin D deficiency, low serum calcium, and secondary hyperparathyroidism with an increase in bone resorption and severe osteopenia. These data offer a rationale for the possible prevention of elevated bone turnover, bone loss, and consequently the reduction of osteoporotic fractures and fracture-induced disability in the oldest olds through the supplementation with calcium and vitamin D.

Genetic analysis of Paraoxonase (PON1) locus reveals an increased frequency of Arg192 allele in centenarians.

Human Paraoxonase (PON1) is a High-Density Lipoprotein (HDL)-associated esterase that hydrolyses lipo-peroxides. PON1 has recently attracted attention as a protective factor against oxidative modification of LDL and may therefore play an important role in the prevention of the atherosclerotic process. Two polymorphisms have been extensively studied: a Leucine (L allele) to Methionine (M allele) substitution at codon 55, and a Glutamine (A allele) to Arginine (B allele) substitution at codon 192. We have examined these two aminoacidic changes in 579 people aged 20 to 65 years old, and 308 centenarians. We found that the percentage of carriers of the B allele at codon 192 (B+ individuals) is higher in centenarians than in controls (0.539 vs 0.447), moreover we found that among the B+ individuals, the phenomenon was due to an increase of people carrying M alleles at codon 55 locus. In conclusion, we propose that genetic variability at PON1 locus affects survival at extreme advanced age.

Development of real time PCR assays for the quantification of Fas and FasL mRNA levels in lymphocytes: studies on centenarians.

Apoptosis plays a central role in the homeostasis of the immune system. During aging, there is an altered regulation of pivotal molecules that are responsible for the regulation of this type of cell death, such as those of the Fas/FasL system. Understanding the regulation of these genes can help to clarify, at least in part, the age-related changes that occur in immune cells. We have developed an original real time PCR assay for quantification of mRNA for Fas and FasL, and have studied a group of young donors, middle aged subjects and centenarians. We have found that the production of Fas mRNA is greatly increased in resting lymphocytes from centenarians; such an increase follows an age-related trend. On the contrary, the production of mRNA for the molecule, which is the natural ligand of Fas, i.e. FasL, is consistently reduced. Our preliminary results suggest that during aging a subtle balance in the production of molecules that cause apoptosis could exist, and that, in order to avoid an excessive death of immune cells, a still unknown mechanism could compensate the increase of Fas with the reduction of FasL.

The MALVA (MAntova LongeVA) study: an investigation on people 98 years of age and over in a province of Northern Italy.

The MALVA (MAntova LongeVA) study aims at investigating the socio-demographic, clinical and genetic characteristics of all subjects over 98 years of age residing in the province of Mantova (Northern Italy). In this paper we present the study protocol and the main demographic results. Absolute number, prevalence ratio and female/male ratio of the subjects aged 98+ and of the centenarians in the Mantova province (370,645 inhabitants at 31st December 1997) were checked at the baseline of the study (31st March 1998) as well as in the two years preceding and following the study. A total of 117 subjects aged 98+ (including 39 centenarians) were traced at 31st March 1998; the prevalence ratio was 31.6 per 100000 (12.1 for centenarians), and the female/male ratio was 6.3 (6.5 for centenarians). The distribution of the oldest old according to places of birth and residence was non-homogeneous across the provincial territory. Seventy-seven subjects (66% of the identified subjects) were enrolled in the study and administered a protocol including an interview about socio-economic conditions, lifetime habits and pathological and pharmacological case histories, as well as medical examination, performance-based tests and blood sample collection. Data on the socio-demographic characteristics and the health status of very old people in the province of Mantova are discussed and compared to findings from previous studies on Italian centenarians.