Self-rated health in individuals with and without disease is associated with multiple biomarkers representing multiple biological domains.

Self-rated health (SRH) is one of the most frequently used indicators in health and social research. Its robust association with mortality in very different populations implies that it is a comprehensive measure of health status and may even reflect the condition of the human organism beyond clinical diagnoses. Yet the biological basis of SRH is poorly understood. We used data from three independent European population samples (N approx. 15,000) to investigate the associations of SRH with 150 biomolecules in blood or urine (biomarkers). Altogether 57 biomarkers representing different organ systems were associated with SRH. In almost half of the cases the association was independent of disease and physical functioning. Biomarkers weakened but did not remove the association between SRH and mortality. We propose three potential pathways through which biomarkers may be incorporated into an individual's subjective health assessment, including (1) their role in clinical diseases; (2) their association with health-related lifestyles; and (3) their potential to stimulate physical sensations through interoceptive mechanisms. Our findings indicate that SRH has a solid biological basis and it is a valid but non-specific indicator of the biological condition of the human organism.

[Principles of biological aging]. / Grundlagen der biologischen Alterung.

The aging process is the substrate on which aging-associated diseases develop; therefore, the scientific discipline of gerontology aims at understanding this biological aging process, which refers to the progressive increase in the risk of death caused by a loss of body functions. Studies in simple model organisms demonstrate that pharmacological substances, genetic interventions and dietary restriction can slow down the process of aging. The cell culture model of cellular senescence gives researchers the opportunity to conduct studies in a system more closely related to the human organism; therefore, cells from different human tissues are cultured in vitro until they stop proliferating. This permanent growth arrest is called cellular senescence. Recent studies have demonstrated that senescent cells also accumulate in many tissues in vivo and contribute to age-related pathologies.

How immunosuppressive therapy affects T cells from kidney transplanted patients of different age: the role of latent cytomegalovirus infection.

The average age of patients receiving renal transplantation is increasing as programmes have been established which support the donation of organs from elderly donors to older recipients. Little is known about the effect of immunosuppressive therapy on the immune system of older patients. In this study, T cell function and the composition of the T cell repertoire were analysed in immunosuppressed renal transplant recipients of different age and cytomegalovirus (CMV) status in comparison to age- and CMV-matched controls. Independent of age and CMV status, the production of interleukin (IL)-2 and interferon (IFN)-γ by T cells was decreased in the patient groups and autologous serum from patients was capable of inhibiting the proliferation of CD3⁺ T cells. CXCR5 expression on T cells was increased in patients versus controls reflecting reduced endogenous IL-2 signalling under immunosuppressive therapy. In CMV-seronegative patients kidney transplantation and immunosuppressive therapy did not induce changes in the CD8⁺ T cell pool, but there was a moderate increase in CD4⁺CD28⁻ effector T cells when compared to age-matched controls. In contrast, latent CMV infection triggered a shift from early to late differentiated CD4⁺ and CD8⁺ T cells in patients and controls. This shift was most pronounced in elderly transplant patients under immunosuppressive therapy. In conclusion, our results demonstrate that immunosuppressive therapy following kidney transplantation is effective in patients older than 65 years. Latent CMV infection, however, accelerates age-related changes in the T cell repertoire in elderly people under immunosuppressive therapy. These patients should therefore be monitored with special care.

Vaccines for the elderly.

Vaccination is the most efficient strategy to prevent infectious disease. The increased vulnerability to infection of the elderly makes them a particularly important target population for vaccination. However, most vaccines are less immunogenic and efficient in the elderly because of age-related changes in the immune system. Vaccination against influenza, Streptococcus pneumoniae and varicella zoster virus is recommended for the elderly in many countries. Various strategies such as the use of adjuvants and novel administration routes are pursued to improve influenza vaccination for the elderly and recent developments in the field of pneumococcal vaccination led to the licensure of protein-conjugated polysaccharide vaccines containing up to 13 serotypes. As antibody titres are generally lower in the elderly and-particularly for inactivated vaccines-decline fast in the elderly, regular booster immunizations, for example against tetanus, diphtheria and, in endemic areas, tick-borne encephalitis, are essential during adulthood to ensure protection of the elderly. With increasing health and travel opportunities in old age the importance of travel vaccines for persons over the age of 60 is growing. However, little is known about immunogenicity and efficacy of travel vaccines in this age group. Despite major advances in the field of vaccinology over the last decades, there are still possibilities for improvement concerning vaccines for the elderly. Novel approaches, such as viral vectors for antigen delivery, DNA-based vaccines and innovative adjuvants, particularly toll-like receptor agonists, will help to achieve optimal protection against infectious diseases in old age.

Fading immune protection in old age: vaccination in the elderly.

The function of the immune system declines with age, leading to an increased occurrence and severity of infectious diseases and a decreased response to vaccines. As the thymus gradually loses its ability to replenish the population of naïve T cells, the memory and effector T cells increase in number and dominate the repertoire. The changes in the naïve and memory T cell pool that occur with ageing in man are discussed here, along with a brief update of the knowledge of B cell populations in the elderly.

[Results from biomedical aging research. Trends and current examples from immunology]. / Ergebnisse aus der biomedizinischen Alternsforschung. Trends und aktuelle Beispiele aus der Immunologie.

The public health of our society is challenged by a continuous increase in life expectancy. Hence, biomedical aging research is enjoying a steadily increasing popularity but also enlightens our understanding of age-related diseases by a number of striking results from basic research. One of the most striking changes that occurs during normal human aging is an overall diminution of immune functions, a phenomenon often termed immunosenescence. Starting from some highly exciting examples from basic immunological research, this article sheds light on which impact normal human aging has on several immune defence mechanisms. In addition, clinical consequences in view of Alzheimer's disease, immunogenicity of vaccines and autoimmune diseases are discussed.

T cells from elderly persons respond to neoantigenic stimulation with an unimpaired IL-2 production and an enhanced differentiation into effector cells.

We analysed the capacity of T cells from young and elderly persons to produce IL-2 and IFN-gamma after in vitro stimulation with two neoantigens, namely inactivated rabies virus and recombinant Etr protein of tick-borne encephalitis virus (TBEV). Soluble antigens should per definition primarly stimulate CD4(+) naïve T cells. Cytokine production was analysed by ELISPOT technology. T cells from elderly and young donors produced similar amounts of IL-2 after priming with both neoantigens. In contrast, IFN-gamma production was induced earlier and at lower antigenic concentrations in T cells from elderly persons than from young controls indicating an enhanced capacity of primed T cells to differentiate into effector cells. In both age groups the response pattern to neoantigenic stimulation was the same whether unfractionated blood mononuclear cells or purified CD4(+)CD45RA(+) T cells with autologous DC as APC were used. The magnitude of the response was, however slightly lower in isolated cells. Autologous DC still induced an MLR in purified CD4(+)CD45RA(+) cells, which was more pronounced in the young than in the elderly group. Our results demonstrate that the ability of CD4(+) T cells from elderly persons to respond to neoantigenic stimulation is intact and that their capacity to differentiate into effector cells is even enhanced. This is in good agreement with earlier reports on alterations in the homing receptor pattern of naïve T cells in old age. Rapid generation of effector cells from naïve cells may at least partly counterbalance the decreasing size of the naïve T cell pool in elderly persons.

Characterization of tick-borne encephalitis virus-specific human T lymphocyte responses by stimulation with structural TBEV proteins expressed in a recombinant baculovirus.

Very little information is available on human T cell responses following exposure to tick-borne encephalitis virus (TBEV) proteins, largely because the virus is a dangerous pathogen and relatively large amounts of purified antigen would be required for the functional characterization of cellular immune responses. We have produced recombinant TBEV proteins using the baculovirus expression system and tested them for their capacity to stimulate T cells in vitro. T lymphocytes from TBEV vaccinated individuals were characterized. The recombinant E and C proteins triggered CD4+ but not CD8+ cells to proliferate and to produce IFN-gamma and IL-5. T cell responses against recombinant NS3 protein were not detected. T cell lines with specificity for the E protein were also established. These lines were CD4+ and had a TH0 cytokine production pattern. Our results demonstrate the utility of recombinant viral proteins to study the generation and characterization of TBEV specific T cell responses.

Changes in the expression of CD31 and CXCR3 in CD4+ naïve T cells in elderly persons.

So far, very few studies exist on the naïve T cell population of elderly persons. Only recently an increase in the percentage of long lived CD4(+)CD31(-) naïve T cells has been claimed to occur with aging. We, therefore, characterised CD31(+) and CD31(-) CD45RA(+) CD4(+) T cells in young and healthy elderly persons. The production of IL-2 and IFN-gamma by the different subpopulations was studied following stimulation with PMA and Ionomycin. The expression of CD28, CD11a, CD62L, CXCR3 and CCR7 was also analysed. The results of this study demonstrate a pronounced increase in the percentage of CD31(-) CD45RA(+) T cells within the CD4 subpopulation of elderly persons. Both, CD31(-) and CD31(+) CD45RA(+) cells expressed CD28, CD62L, were CD11a (dim) and produced IL-2 but no IFN-gamma. This phenotype confirms that they were naïve T cells. IL-2 production by naïve T cells was not impaired in elderly persons. Interestingly, CD31(+) as well as CD31(-) naïve T cells contained a subpopulation of CXCR3(+) cells in elderly individuals, but not in young ones. In spite of expressing this chemokine receptor that enables the cells to migrate into inflammatory tissues, they were still CCR7(+) and CD62L(+). We speculate that due to previous contact with local environmental factors, this subset of naïve T cells acquires a different chemokine receptor phenotype, resulting in an altered migratory capacity in old age. Aberrant contact with antigen and effector cell differentiation in unorthodox locations may be the consequence. This could also affect Th1/Th2 polarisation, which is known to be impaired in elderly persons.

CD4+ and CD8+ mediated cellular immune response to recombinant influenza nucleoprotein.

The stimulatory properties of soluble recombinant influenza nucleoprotein (NP) on purified CD4(+) and CD8(+) T cells from young and elderly individuals were studied. Recombinant influenza NP failed to induce proliferation of resting CD4(+) and CD8(+) T cells in the absence of IL-2. Addition of small amounts of IL-2, however, led to strong proliferation of resting CD4(+) and CD8(+) T cells from young and elderly donors. NP-reactive CD4(+) and CD8(+) T cell lines from both age groups grew equally well under long-term culture conditions. T cell lines raised to live influenza virus could recognize recombinant influenza NP and showed a substantial proliferative response. Stimulation of CD8(+) T cells is presumably due to cross-presentation, as EBV-transformed MHC class I-positive cell lines, which are incapable of antigen processing, stimulated live influenza virus-reactive CD8(+) T cell lines when loaded with NP-derived immunodominant peptides but not following loading with the whole NP molecule. Vaccines containing recombinant influenza NP might confer cross-protective immunity and could therefore be especially useful in cases of major epidemics or pandemics.

Ibuprofen decreases cytokine-induced amyloid beta production in neuronal cells.

Trying to decrease the production of Amyloid beta (Abeta) has been envisaged as a promising approach to prevent neurodegeneration in Alzheimer's disease (AD). A chronic inflammatory reaction with activated microglia cells and astrocytes is a constant feature of AD. The participation of the immune system in the disease process is further documented in several retrospective clinical studies showing an inverse relationship between the prevalence of AD and nonsteroidal anti-inflammatory drug (NSAID) therapy. Previously, we demonstrated that the combination of the proinflammatory cytokines TNFalpha with IFNgamma induces the production of Abeta-42 and Abeta-40 in human neuronal cells. In the present study, the neuronal cell line Sk-n-sh was incubated for 12 h with the cyclooxygenase inhibitor ibuprofen and subsequently stimulated with the cytokines TNFalpha and IFNgamma. Ibuprofen treatment decreased the secretion of total Abeta in the conditioned media of cytokine stimulated cells by 50% and prevented the accumulation of Abeta-42 and Abeta-40 in detergent soluble cell extracts. Viability of neuronal cells measured by detection of apoptosis was neither influenced by ibuprofen nor by cytokine treatment. The reduction in the production of Abeta by ibuprofen was presumably due to a decreased production of betaAPP, which in contrast to the control proteins M2 pyruvate kinase, beta-tubulin and the cytokine inducible ICAM-1 was detected at low concentration in ibuprofen treated cells. The data demonstrate a possible mechanism how ibuprofen may decrease the risk and delay the onset of AD.

Diagnostic immunoassays for tick-borne encephalitis virus based on recombinant baculovirus protein expression.

The baculovirus expression system that utilizes Autographa californica nuclear polyhedrosis virus was used to express the highly antigenic envelope protein E of a tick-borne encephalitis (TBE) complex virus, as well as a C-terminally truncated form of protein E (Etr). The recombinant proteins were produced with a histidine-tag at their carboxy-terminus. Protein purification by nickel agarose chromatography resulted in high concentrations of pure Etr protein, but only poor yields of E protein. Therefore, Etr was used to develop a sensitive and specific enzyme-linked immunosorbent assay (ELISA), as well as an immunoblot assay to detect TBE virus-specific antibodies in sera from immunized human blood donors. Sera from non-vaccinated blood donors were used as controls. The data show that the recombinant TBE virus-specific Etr protein exhibits the antigenic epitopes and conformation necessary for specific antigen-antibody recognition. Thus, the baculovirus expression system provides a cheap and easy method to generate recombinant viral antigens for TBE virus-specific serodiagnosis.

Costimulatory effects of interferon-gamma and interleukin-1beta or tumor necrosis factor alpha on the synthesis of Abeta1-40 and Abeta1-42 by human astrocytes.

Chronic inflammation and astrocytosis are characteristic histopathological features of Alzheimer's Disease (AD). Astrocytes are one of the predominant cell types in the brain. In AD they are activated and produce inflammatory components such as complement components, acute phase proteins, and cytokines. In this study we analyzed the effect of cytokines on the production of amyloid beta (Abeta) in the astrocytoma cell line U373 and in primary human astrocytes isolated postmortem from healthy aged persons as well as from patients with AD. Astrocytes did not produce Abeta in the absence of stimuli or following stimulation with IL-1beta, TNFalpha, IL-6, and TGF-beta1. Neither did combinations of TNFalpha and IL-1beta, IL-6 or TGF-beta1, or the coadministration of IFNgamma and IL-6 or TGF-beta1 induce Abeta production. In contrast, pronounced production of Abeta1-40 and Abeta1-42 was observed when primary astrocytes or astrocytoma cells were stimulated with combinations of IFNgamma and TNFalpha or IFNgamma and IL-1beta. Induction of Abeta production was accompanied by decreased glycosylation of APP as well as by increased secretion of APPsbeta. Our results suggest that astrocytes may be an important source of Abeta in the presence of certain combinations of inflammatory cytokines. IFNgamma in combination with TNFalpha or IL-1beta seems to trigger Abeta production by supporting beta-secretase cleavage of the immature APP molecule.

Decreased thyroid peroxidase expression in cultured thyrocytes after external gamma irradiation.

Impairment of thyroid function has been described in up to 50% of the patients after external irradiation of the neck region as well as after mantle irradiation. In order to assess radiation-induced alterations in cultured thyroid cells, the occurrence of apoptosis and necrosis as well as the expression of thyroid peroxidase (TPO) and of two members of the 70 kD heat shock family, HSP-73 and HSP-72, were analysed following gamma irradiation. Human thyroid epithelial cells (TEC) were purified from surgical tissue specimens, were cultured and irradiated with a single dose of 5 Gy or 50 Gy using Co60 as radioactive source. Analysis was performed 1, 3 and 5 day(s) after irradiation. Apoptosis and necrosis were assessed by DNA staining with propidium iodide and FACS analysis. TPO and HSP expression by SDS-PAGE and Western blotting. The cell viability of TEC was not affected by irradiation and there was no induction of HSP-72, a sensitive indicator of acute cellular stress. Interestingly, the expression of TPO, a key enzyme of thyroid hormone synthesis, decreased significantly in irradiated TEC, while HSP-73 expression remained unchanged. Decreased expression of TPO with a resulting suppression of thyroid hormone synthesis could contribute to an early development of thyroid dysfunction following irradiation. Thus, analysis of thyroid function, even early after external radiation therapy of the neck or after total body irradiation, seems to be indicated.

The amyloid beta peptide abeta (25-35) induces apoptosis independent of p53.

Apoptosis of neuronal cells apparently plays a role in Alzheimer's disease (AD). The amyloid beta (Abeta) peptide derived from beta-amyloid precursor protein is found in AD brain in vivo and can induce apoptosis in vitro. While p53 accumulates in cells of AD brain, it is not known if p53 plays an active role in Abeta-induced apoptosis. We show here that inactivation of p53 in two experimental cell lines, either by expression of the papillomavirus E6 protein or by a shift to restrictive temperature, does not affect apoptosis induction by Abeta (25-35), indicating that Abeta induces apoptosis in a p53-independent manner.