Nazzarena Gasparini

Novel -209A/G MT2A polymorphism in old patients with type 2 diabetes and atherosclerosis : relationship with inflammation (IL-6) and zinc

Vascular complications, including ischaemic cardiomyopathy, are the major causes of death in old diabetic patients. Chronic inflammation due to high IL-6 production occurs in type 2 diabetes (NIDDM) and atherosclerosis. High levels of IL-6 are associated with hyperglycaemia, dyslipidemia and provoke insulin resistance. In ageing and inflammation, IL-6 affects Metallothionein (MT) homeostasis, which in turn is involved in zinc turnover. Zinc deficiency is an usual event in ageing, inflammation, type 2 diabetes and atherosclerosis. No genetic study exists on MT polymorphisms in NIDDM-atherosclerotic patients. The aim of the present study is to screen a single nucleotide polymorphism in the promoter region of the MT2A gene in relation to inflammation (IL-6) and plasma zinc in NIDDM-atherosclerotic patients. The -209 A/G MT2A polymorphism is associated with chronic inflammation (higher plasma levels of IL-6), hyperglycaemia, enhanced HbA1c and more marked zinc deficiency in AA than AG genotype carrying patients. Analysing patients and controls subdivided in AA and AG genotypes, significant interactions existed between disease status and genotypes for glucose and zinc. AA patients are more at risk of developing NIDDM in association with atherosclerosis (p = 0.0015 odds ratio = 2.617) and its complications, such as ischaemic cardiomyopathy (p = 0.0050 odds ratio = 12.6). In conclusion, high levels of IL-6 unmask the phenotypes (higher insulin resistance and zinc deficiency) in relation to the genotypes with subsequent risk of developing ischaemic cardiomyopathy in NIDDM-atherosclerotic patients carrying AA genotype. Hence, the novel -209A/G MT2A polymorphism may be a further useful tool for the prevention, diagnosis and therapy of these combined pathologies in the elderly.

Metallothioneins/PARP-1/IL-6 interplay on natural killer cell activity in elderly: parallelism with nonagenarians and old infected humans. Effect of zinc supply

Metallothioneins (MTs) play pivotal role in zinc-related cell homeostasis because of their high affinity for this trace element which is in turn relevant against oxidative stress and for the efficiency of the entire immune system, including natural killer (NK) cell activity. In order to accomplish this role, MTs sequester and/or dispense zinc during stress and inflammation to protect cells against reactive oxygen species. MTs gene expression is affected by IL-6 for a prompt immune response. Concomitantly, MTs release zinc for the activity of antioxidant zinc-dependent enzymes, including poly(ADP-ribose)polymerase-1(PARP-1), which is involved in base excision DNA-repair. This role of MTs is peculiar in young adult-age during transient stress and inflammation, but not in ageing because stress-like condition and inflammation are persistent. This may lead MTs to turn-off from role of protection in young age to deleterious one in ageing with subsequent appearance of age-related diseases (severe infections). The aim is to study the role played by MTs/IL-6/PARP-1 interplay on NK cell activity in elderly, in old infected patients (acute and remission phases by bronchopneumonia infection) and in health nonagenarian/centenarian subjects. MTmRNA is high in lymphocytes from elderly people coupled with high IL-6, low zinc ion bioavailability, decreased NK cell activity and impaired capacity of PARP-1 in base excision DNA-repair. The same trend in this altered physiological cascade during ageing also occurs in old infected patients (both acute and remission phases) with more marked immune damage, inflammatory condition and very impaired PARP-1 in base excision DNA-repair. By contrast, centenarian subjects display low MTmRNA, good zinc ion bioavailability, satisfactory NK cell activity and higher capacity of PARP-1 in base excision DNA-repair. These findings clearly demonstrate that the sequester of zinc by MTs in ageing is deleterious because leading to low zinc ion bioavailability with subsequent impairment of PARP-1 and NK cell activity and appearance of severe infections. Physiological zinc supply (12 mg Zn(++)/day) for 1 month in elderly and in old infected patients (remission phase) restores NK cells activity with values observed in health centenarians. Therefore, the zinc ion bioavailability by zinc-bound MTs homeostasis is pivotal to reach health longevity and successful ageing.

MtmRNA gene expression, via IL-6 and glucocorticoids, as potential genetic marker of immunosenescence: lessons from very old mice and humans

Metallothioneins (MTs) are involved in metal-related cell homeostasis because of their high affinity for metals forming clusters. The main functional role of MTs is to sequester and/or dispense zinc participating in zinc homeostasis, which is relevant in normal immune response. Consistent with this role, MTs gene expression (MTmRNA) is transcriptionally induced by a variety of stressing agents to protect cells from reactive oxygen species. In order to accomplish this task, MTs gene expression is affected by glucocorticoids and IL-6 for a prompt immune response. This protection is peculiar in young-adult age during transient stress and inflammatory condition, but not in ageing because stress-like condition and inflammation are constant for the whole circadian cycle. This may lead MTs to turn-off from role of protection in young age to deleterious one in ageing. The aim is to suggest MTmRNA as potential genetic marker of immunosenescence. Liver MTmRNA, IL-6 and glucocorticoids levels are high, whereas the bioavailability of zinc ions is low and natural killer cells activity is depressed in old and very old mice during the light period as compared to young in the same period. An inversion of nutritional-endocrine-immune profile exclusively occurs in young mice during the night showing the existence of immune plasticity. No inversion occurs in old mice during the night. As a consequence, no immune plasticity in old mice ensues. By contrast, very old mice remodel the altered MTmRNA and immune-endocrine profile during the night up to values of young ones observed during the light period. Therefore, the remodelling of MTmRNA may be involved in the maintenance of immune plasticity with subsequent successful ageing. Thus, MTmRNA, via IL-6 and glucocorticoids, may be potential genetic marker of immunosenescence. This assumption is reinforced by low MTmRNA in lymphocytes of nonagenarians and young-adult people in comparison with elderly and Downs syndrome subjects.

The variations during the circadian cycle of liver CD1d-unrestricted NK1.1+TCRγ/δ+ cells lead to successful ageing. Role of metallothionein/IL-6/gp130/PARP-1 interplay in very old mice

Abstract NKT cells derive from the thymus and home to the liver. Liver NKT cells can be divided in two groups: ‘classical’ and ‘non-classical’. The first is CD1d-restricted, the second is CD1d-unrestriced. NKT cells (classical and non-classical) co-express T-cell receptor (TCR) and NK-cell marker (NK1.1), display cytotoxicity and produce IFN-γ under IL-12 stimulation affecting, thereby, Th1 response and innate immunity. NK1.1 + TCRα/β + cells belong to both groups. NK1.1 + TCRγ/δ + cells belong to the second group. Anyway, both NKT cell subtypes, via IFN-γ production, protect against viruses and bacteria from early in life. Immune variations as well as zinc rhythmicity during the circadian cycle confer the immune plasticity, which is essential for successful ageing. Liver NK1.1 + TCRγ/δ + cells, rather than TCRα/β + , from young and very old mice display ‘in vitro’ (under IL-12 stimulation) nocturnal peaks in cytotoxicity and IFN-γ production. The acrophase of liver NK1.1 + TCRγ/δ + cells is present in young and very old mice, not in old. The interplay among zinc-bound metallothionein (MT)/IL-6/gp130/poly(ADP-ribose) polymerase-1 (PARP-1) may be involved in conferring plasticity to liver NK1.1 + TCRγ/δ + cells. IL-6, via sub-unit receptor gp130, induces MTmRNA. At night, gene expressions of MT, IL-6, gp130 are lower in very old mice than old and young MT-I transgenic mice (MT-I ∗ ). In very old mice, this phenomenon allows limited sequester of intracellular zinc from MT leading to good free zinc ion bioavailability for immune efficiency and zinc-dependent PARP-1 activity. Indeed (1) in vitro, high IL-6 provokes strong accumulation of MT, impaired cytotoxicity and low zinc ion bioavailability in liver NK1.1 + TCRγ/δ + cells exclusively from old and MT-I ∗ mice. (2) The ratio total/endogen PARP-1 activity is higher in very old than in old and MT-I ∗ mice, suggesting a higher capacity of PARP-1 in base excision DNA-repair in very old age thanks to low zinc-bound MT. Cytotoxicity and IFN-γ production from liver NK1.1 + TCRγ/δ + cells are thus preserved leading to successful ageing. In conclusion, MT/IL-6/gp130/PARP-1 interplay may confer plasticity to liver CD1d-unrestricted NK1.1 + TCRγ/δ + cells, where MT, IL-6, gp130 are the main upstream protagonists, and PARP-1 is the main downstream protagonist in immunosenescence.

1267 HSP70-2 polymorphism as a risk factor for carotid plaque rupture and cerebral ischaemia in old type 2 diabetes-atherosclerotic patients

Patients with type 2 diabetes mellitus (NIDDM) are at risk for macrovascular disease complications, such as myocardial infarction (MI) or stroke from plaque rupture. Cytokines play a key role in plaque vulnerability. IFN-gamma inhibits collagen synthesis thereby affecting plaque stability. High IL-6, TNF-alpha, and dyslipidemia are risk factors for thrombosis. Abnormal increments of HSP70 in atherosclerotic plaques might lead to plaque instability and rupture caused by chronic inflammation, which up-regulates the expression of pro-inflammatory cytokines (IL-6 and TNF-alpha) in human monocytes. Studies of a polymorphic PstI site lying in the coding region at position 1267 of the HSP70-2 gene have shown that the BB genotype is associated with NIDDM. We screened 60 old NIDDM patients with carotid stenosis and 107 old healthy controls for 1267 HSP70-2 polymorphism in order to establish if an association with plaque frailty exists. Different genotypic distributions were observed between patients and healthy controls. An increased relative risk was associated with the B allele (p = 0.0107; odds ratio = 1.861). HSP70-2, IL-6, IFN-gamma, TNF-alpha gene expressions within the plaques and serum levels of triglyceride, total cholesterol and LDL cholesterol were tested from patients stratified according to their B+ (AB and BB) and B- (AA) genotypes. Plaque morphology (soft or fibrous-calcified) and the incidence of cerebral ischaemia were also assessed. B+ patients showed increased HSP70-2, IL-6, IFN-gamma, TNF-alpha and dyslipidemia as compared to B- carriers. The frequency of soft plaques increased in B+ in comparison to B- patients (67% versus 13%; odds ratio 13.0, p = 0.0006). A higher frequency of cerebral ischaemia (ictus or transient ischaemic attack (TIA)) was present in B+ than in B- genotype (53% versus 20%; odds ratio 4.57, p < 0.05) Hence, 1267 HSP70-2 polymorphism may be of use in identifying B+ NIDDM patients at risk for carotid plaque rupture and cerebral ischaemia.

Metallothioneins (I+II) and thyroid-thymus axis efficiency in old mice: role of corticosterone and zinc supply.

Abstract Thymic atrophy or thymus absence causes depressed thyroid–thymus axis (TTA) efficiency in old, young propyl-thiouracil (PTU) (experimental hypothyroidism) and in young-adult thymectomised (Tx) mice, respectively. Altered zinc turnover may be also involved in depressed TTA efficiency. Zinc turnover is under the control of zinc-bound metallothioneins (Zn-MTs) synthesis. Thyroid hormones, corticosterone and nutritional zinc affect Zn-MT induction. Zn-MT releases zinc in young-adult age during transient oxidative stress for prompt immune response. In constant oxidative stress (ageing and liver regeneration after partial hepatectomy), high liver Zn-MTs, low zinc ion bioavailability and depressed TTA efficiency appear. This last finding suggested that MT might not release zinc during constant oxidative stress leading to impaired TTA efficiency. The aim of this work/study is to clarify the role of Zn-MTs (I+II) in TTA efficiency during development and ageing. The main results are (1) Old and PTU mice display high corticosterone, enhanced liver MTmRNA, low zinc and depressed TTA efficiency restored by zinc supply. Increased survival and no significant increments in basal liver Zn-MTs proteins occur in old and PTU mice after zinc supply. (2) Lot of zinc ions bound with MT in the liver from old mice than young (HPLC). (3) Young-adult Tx mice, evaluated at 15 days from thymectomy, display high MTmRNA and nutritional–endocrine–immune damage restored by zinc supply or by thymus grafts from old zinc-treated mice. (4) Young-adult Tx mice, but evaluated at 40 days from thymectomy, display natural normalisation in MTmRNA and nutritional–endocrine–immune profile with survival similar to normal mice. (5) Stressed (constant dark for 10 days) mice overexpressing MT display low zinc, depressed immunity, reduced thymic cortex, high corticosterone, altered thyroid hormones turnover showing a likeness with old mice. These findings, taken altogether, show that corticosterone is pivotal in MTs induction under stress. MTs bind preferentially zinc ions in constant oxidative stress, but with no release of zinc from MT leading to impaired TTA efficiency. Zinc supply restores the defect because zinc has no interference in affecting pre-existing Zn-MTs protein concentrations in old and PTU mice. Therefore, free zinc ions are available for TTA efficiency after zinc supply. Thymus from old zinc-treated mice induces the same restoring effect when transplanted in Tx recipients. However, Tx mice display natural normalisation in MTmRNA and in nutritional–endocrine–immune profile in the long run. Therefore, Zn-MTs (I+II) are crucial in zinc homeostasis for endocrine–immune efficiency during the entire life assuming a role of potential and novel ‘biological clock of ageing’.

Are zinc-bound metallothionein isoforms (I+II and III) involved in impaired thymulin production and thymic involution during ageing?

BackgroundWith advancing age, thymic efficiency shows progressive decline due to thymic involution allowing impaired cell-mediated immunity and the appearance of age-related diseases. The intrinsic cause of thymic involution is still undefined. Chronic inflammation and high glucocorticoids (GCs) may be involved. However, transgenic mice, with increased GC sensitivity and over expression of GC receptors, display delayed age-associated thymic involution. This fact suggests that other substances may affect thymic involution. Among them, both isoforms of metallothioneins (MTs) I+II and III are the major candidates because their increments leads to organ atrophy in constant stress and are induced by IL-6, which increases in ageing. Enhanced MTs in ageing allows constant sequester of zinc ions and no subsequent zinc release leading to low zinc ion bioavailability for thymic efficiency. This sequester is very limited in very old age. Thus, we have investigated the MTmRNA (I+II and III) in the thymus from young, old and very old mice.MethodsMTmRNA and IL-6mRNA (RT-PCR) in the thymus from different donors were tested. Concomitantly, TECs proliferation, zinc ion bioavailability (ratio total thymulin/active thymulin), thymulin activity and corticosterone were tested from different donors.ResultsBoth isoforms of MTmRNA and IL-6mRNA increase in old thymus coupled with low zinc ion bioavailability, reduced TECs proliferation, impaired thymulin activity and enhanced plasma corticosterone in comparison with young. Conversely, although the thymus is involuted in very old mice because of no changes in thymus weight in comparison to old mice, reduced MTmRNA, especially MT-I+II isoforms, and low IL6mRNA occur. Concomitantly, good zinc ion bioavailability, maintained TECs proliferation, satisfactory thymulin activity and reduced corticosterone are observed in very old mice.ConclusionsThe concomitant increments by high IL-6 of both MT isoforms in the thymus from old mice may be involved in thymic involution because provoking low zinc ion bioavailability, which is relevant for thymic efficiency. By contrast, the limited increments of MTs by low IL-6 induce good zinc ion bioavailability and satisfactory thymic efficiency in very old mice. Therefore, abnormal increased MTs may provoke complete thymic involution during ageing and the possible appearance of age-related diseases. If their increments are instead limited by low inflammation, healthy ageing and longevity may be reached.

Metallothionein (I+II) confers, via c-myc, immune plasticity in oldest mice: model of partial hepatectomy/liver regeneration

Abstract Because of its similarity to ageing in impaired immune efficiency 48 h after surgical procedures on young partially hepatectomised mice, partial hepatectomy/liver regeneration (pHx) provides a good model for the study of inflammation in ageing. In old age, high metallothionein (I+II) (MT) sequesters a substantial number of intracellular zinc ions consequently leading to low zinc ion bioavailability for an adequate immune response. Corticosterone and IL-6 affect MTmRNA induction in inflammation and after pHx against oxidative damage. The aim of this study was to investigate the role played by MT in conferring immune plasticity in ageing and in very old age using the pHx model. 48 h after their partial hepatectomy, the crude zinc balance was negative in young, old and very old mice coupled with increased MT, corticosterone, sIL-6R and IL-6. Concomitantly, Natural Killer (NK) cell activity and IL-2 production decreased. Complete restoration of the nutritional–endocrine–immune parameters occurred 15 days from the surgical procedures in young and very old mice, but not in old or transgenic mice overexpressing MT. A significant positive or inverse correlation among nutritional–endocrine–immune parameters exists in young and very old mice, but not in old mice during liver regeneration. Since MT also affects c-myc, the gene expression of c-myc declines from 48 h to days 7 and 15 after pHx in young and very old mice, but remains constantly high in old pHx mice for the same days. This circumstance leads to the appearance of tumours in the long run in old pHx mice and survival times that are shorter than old sham controls. Because complete remodelling also occurs in IL-6 and in sIL-6R in very old mice during liver regeneration, the pre-existing inflammation is not detrimental in very old age. As such, very old mice are still responsive to large inflammation, such as pHx, thanks to correct MT homeostasis. Correct MT homeostasis, via c-myc, is therefore pivotal in both suitable liver regeneration and in conferring immune plasticity with subsequent successful ageing. High MT plays an extremely harmful role in ageing: on one hand it lowers zinc ion bioavailability levels required for immune efficiency and on the other hand it increases c-myc expression. The combination of immune depression and enhanced c-myc, via high MT, may trigger the appearance of age-related degenerative diseases.

Comparison of intracellular zinc signals in nonadherent lymphocytes from young-adult and elderly donors: role of zinc transporters (Zip family) and proinflammatory cytokines

Intracellular zinc homeostasis is crucial in regulating the inflammatory/immune response at any age. It is tightly regulated by zinc transporters that control influx, efflux and compartmentalization of zinc within the cells. Specific methods for detecting the age-related differences in intracellular zinc signaling are poorly described. We report a novel assay induced after the in vitro zinc addition in peripheral blood mononuclear cells (PBMCs) and in lymphocytes from young and old donors in the absence/presence of in vitro zinc depletion (using EDTA). The intracellular labile zinc variations are monitored over time by flow cytometry using Fluozin-3 AM probe. The best curve fit of the data is calculated using a nonlinear regression model defined as follows: pr3/[1+Exp(-pr1-pr2*Xt)]. Pr1 depends on the initial free zinc value (time 0); pr2 describes the rate of the speed in reaching the maximum intracellular free zinc concentration; pr3 represents the maximum intracellular zinc increment (plateau curve); Xt is the time course. Age-related intracellular free zinc variations occur in PBMCs and lymphocytes incubated in EDTA-supplemented medium. The higher plateau of the curve (pr3) was observed in younger subjects. An up-regulation of Zip genes (Zip1, Zip2, Zip3), influencing zinc influx, is more pronounced in the young than old donors. Interleukin-6 and tumor necrosis factor-α overproduction was enhanced in old individuals, suggesting the presence of more marked zinc deficiency and chronic inflammation. In conclusion, the determination of intracellular zinc signals induced by in vitro zinc addition using logistic parameters may be useful to estimate the rate of intracellular zinc homeostasis and its role in inflammatory/immune response in aging.

In vivo effect of alpha-bisabolol, a nontoxic sesquiterpene alcohol, on the induction of spontaneous mammary tumors in HER-2/neu transgenic mice.

Breast cancer represents the most commonly diagnosed invasive malignancy in pre- and postmenopausal women in both developed and underdeveloped countries. Taking into account that treatment options, including surgery, have not been able to deal with the growing incidence of breast malignancy, it is required to develop mechanism-based novel agents for its prevention. Wide interest in some natural compounds as antiinflammatory agents and as alternative to the traditional medicines is increasing because they do not provoke any adverse effects and are effective in multiple organs, alpha-Bisabolol (BISA), a small oily sesquiterpene alcohol, was reported as chemopreventive agent in induced rat mammary carcinogenesis. The aim of the present study is to investigate the role played by two doses of BISA (via intramammary infusion) on the induction and development of mammary tumor in HER-2/neu transgenic mice as well as the BISA effect after tumor surgical resection. The main data show that (a) optimal dosage of BISA is 10 mg/mouse rather than 3.6 mg/mouse with no adverse effects (e.g., alopecia); (b) the number of the palpable tumor masses decreases in mice treated with 10 mg/mouse of BISA; (c) mice after surgical resection of the primary tumor and treatment with BISA (10 mg) are free from tumor for more weeks, after the surgical treatment; (d) using array analysis, some genes implicated in carcinogenesis mechanisms (NF-kappaBia, Map2k, Mapkl4, and HER2/ neu), angiogenesis process (Fgf), and inhibition of apoptosis (Birc5) are differently regulated after BISA treatment, with a downregulation of the HER2/neu as well as of Fgf and Birc5 genes; (e) the NK cell cytotoxicity increases in tumor-treated mice, especially after the removal of the first tumor mass. Such effectiveness could be important to achieve goals for a possible combination of BISA to conventional therapies in breast cancer and to tumor surgical removal (adjuvant therapy), as suggested for other sesquiterpene analogs.