Oscar Okwudiri Onyema

Circulating Heat Shock Protein 70 in Health, Aging and Disease

BackgroundHeat shock proteins (Hsp) are ubiquitously synthesised in virtually all species and it is hypothesised that they might have beneficial health effects. Recent studies have identified circulating Hsp as an important mediator in inflammation - the effects of low-grade inflammation in the aging process are overwhelming. While much is known about intracellular Hsp70, scant data exist on circulating Hsp70 in the aging context. Therefore, the objectives of this study were to investigate the effect of age and disease on circulating Hsp70 and, in particular, to evaluate the association between circulating Hsp70 and inflammatory parameters.ResultsSerum Hsp70, Interleukin (IL) -10, IL-6 and Tumor Necrosis Factor (TNF) alpha concentrations were determined in 90 hospitalised geriatric patients (aged 83 ± 6 years) and in 200 community-dwelling control subjects (100 elderly, aged 74 ± 5 years, and 100 young, aged 23 ± 3 years). In the community-dwelling elderly, serum Hsp70 and IL-10 concentrations were significantly lower and IL-6 was significantly higher when compared to healthy young control subjects. Elderly patients presenting inflammation (CRP serum levels ≥5 mg/L) showed significantly (p = 0.007) higher Hsp70 values; and Hsp70 correlated positively (p < 0.001) with IL-6 and CRP, but not with TNF-alpha or IL-10. A significant association was also noted between Hsp70 levels and the degree of dependency and cognitive decline in geriatric patients.ConclusionsThe present data provide new evidence that serum concentration of Hsp70 decreases with age in a normal population. Our study also shows that higher levels of Hsp70 are associated with inflammation and frailty in elderly patients.

Class II HDAC Inhibition Hampers Hepatic Stellate Cell Activation by Induction of MicroRNA-29

Background The conversion of a quiescent vitamin A storing hepatic stellate cell (HSC) to a matrix producing, contractile myofibroblast-like activated HSC is a key event in the onset of liver disease following injury of any aetiology. Previous studies have shown that class I histone deacetylases (HDACs) are involved in the phenotypical changes occurring during stellate cell activation in liver and pancreas. Aims In the current study we investigate the role of class II HDACs during HSC activation. Methods We characterized the expression of the class II HDACs freshly isolated mouse HSCs. We inhibited HDAC activity by selective pharmacological inhibition with MC1568, and by repressing class II HDAC gene expression using specific siRNAs. Results Inhibition of HDAC activity leads to a strong reduction of HSC activation markers α-SMA, lysyl oxidase and collagens as well as an inhibition of cell proliferation. Knock down experiments showed that HDAC4 contributes to HSC activation by regulating lysyl oxidase expression. In addition, we observed a strong up regulation of miR-29, a well-known anti-fibrotic miR, upon treatment with MC1568. Our in vivo work suggests that a successful inhibition of class II HDACs could be promising for development of future anti-fibrotic compounds. Conclusions In conclusion, the use of MC1568 has enabled us to identify a role for class II HDACs regulating miR-29 during HSC activation.

Effects of Physical Exercise on Markers of Cellular Immunosenescence: A Systematic Review

Aging affects negatively the immune system, defined as immunosenescence, which increases the susceptibility of elderly persons to infection, autoimmune disease, and cancer. There are strong indications that physical exercise in elderly persons may prevent the age-related decline in immune response without significant side effects. Consequently, exercise is being considered as a safe mode of intervention to reduce immunosenescence. The aim of this review was to appraise the existing evidence regarding the impact of exercise on surface markers of cellular immunosenescence in either young and old humans or animals. PubMed and Web of Science were systematically screened, and 28 relevant articles in humans or animals were retrieved. Most of the intervention studies demonstrated that an acute bout of exercise induced increases in senescent, naïve, memory CD4+ and CD8+ T-lymphocytes and significantly elevated apoptotic lymphocytes in peripheral blood. As regards long-term effects, exercise induced increased levels of T-lymphocytes expressing CD28+ in both young and elderly subjects. Few studies found an increase in natural killer cell activity following a period of training. We can conclude that exercise has considerable effects on markers of cellular aspects of the immune system. However, very few studies have been conducted so far to investigate the effects of exercise on markers of cellular immunosenescence in elderly persons. Implications for immunosenescence need further investigation.

Aging-associated subpopulations of human CD8+ T-lymphocytes identified by their CD28 and CD57 phenotypes.

BACKGROUND During organismal aging, human T-cells shift towards less functional phenotypes, often called senescent cells. As these cells have not been well characterized, we aimed to relate surface markers of human T-cell senescence with characteristics of in vitro cellular aging and to further characterize these cells. METHODS We identified, by flow cytometry, subpopulations of CD8+ T-cells based on CD57 and CD28 expression, and tested them for some markers of cellular senescence, apoptosis, differentiation and homing. RESULTS Elderly persons presented significantly higher proportions not only of CD28-CD57+, but also of CD28+CD57+ cells. CD28+CD57+ cells had the highest expression of p16, p21, Bcl-2, CD95, CD45RO, CCR5 and PD-1, thereby arguing in favor of a senescent phenotype. CONCLUSION Among CD8+ T-lymphocytes, CD28+CD57+ cells represent a subset with some senescent features that are distinct from the CD28-CD57+ cells.

Shortcomings in the Application of Multicolour Flow Cytometry in Lymphocyte Subsets Enumeration

The lymphoid system is composed of numerous phenotypically distinct subsets of cells, each of which has a unique role in the effectiveness of an immune response. To distinguish specifically between these subsets, it is mandatory to detect simultaneously different cell surface antigens. This became feasible by the development of multicolour flow cytometric technologies. With these techniques, researchers now have the opportunity to study individual cells in far greater detail than previously possible. However, proper data analysis, interpretation and presentation of results will require a high level of understanding of the intricacies of the technology and the inherent limitations of the acquired data. The present report is intended to contribute to the better understanding of how the flow cytometer operates. This report may help new and inexperienced users to work appropriately with the flow cytometer.

Shifts in subsets of CD8+ T-cells as evidence of immunosenescence in patients with cancers affecting the lungs: an observational case-control study

BackgroundShifts in CD8+ T-cell subsets that are hallmarks of immunosenescence are observed in ageing and in conditions of chronic immune stimulation. Presently, there is limited documentation of such changes in lung cancer and other malignancies affecting the lungs.MethodsChanges in CD8+ T-cell subsets, based on the expression of CD28 and CD57, were analysed in patients with various forms of cancer affecting the lungs, undergoing chemotherapy and in a control group over six months, using multi-colour flow cytometry.ResultsThe differences between patients and controls, and the changes in the frequency of CD8+ T-cell subpopulations among lung cancer patients corresponded to those seen in immunosenescence: lower CD8-/CD8+ ratio, lower proportions of CD28+CD57- cells consisting of naïve and central memory cells, and higher proportions of senescent-enriched CD28-CD57+ cells among the lung cancer patients, with the stage IV lung cancer patients showing the most pronounced changes. Also observed was a tendency of chemotherapy to induce the formation of CD28+CD57+ cells, which, in line with the capacity of chemotherapy to induce the formation of senescent cells, might provide more evidence supporting CD28+CD57+ cells as senescent cells.ConclusionImmunosenescence was present before the start of the treatment; it appeared to be pronounced in patients with advanced cases of malignancies affecting the lungs, and might not be averted by chemotherapy.

Association Between Immunosenescence Phenotypes and Pre-frailty in Older Subjects: Does Cytomegalovirus Play a Role?

Frailty is highly prevalent in old age and confers an important mortality risk. Although the causes of frailty are multiple, immunosenescence (IS)-predominantly driven by cytomegalovirus (CMV)-has been implicated in its pathophysiology. Thus far, research examining the association between IS and frailty states is sparse and equivocal. On the other hand, evidence is mounting in support of the view that frailty can be reversed, especially for those in the pre-frail stage. Therefore, we aimed to clarify the impact of CMV on IS and its relevance to pre-frailty. One hundred seventy-three persons aged 80 to 99 years were enrolled. Pre-frailty was defined according to Frieds criteria. Anti-CMV IgG and serum IL-6 were measured using Architect iSystem and Luminex, respectively. T-cell phenotypes were determined using flow cytometry. The prevalence of pre-frailty was 52.6%, increased with age (p = .001), and was greater in men than women (p = .044). No relationship was found between pre-frailty and positive CMV serology. Further, CMV-seropositivity was significantly associated with less naïve cells, more memory and senescence-prone phenotypes (all p < .001). After adjusting for potential confounders, only IL-6, age and sex were predictive of pre-frailty. We conclude that the presence of pre-frailty is independent from CMV infection in very old subjects.

Strength Endurance Training but Not Intensive Strength Training Reduces Senescence-Prone T Cells in Peripheral Blood in Community-Dwelling Elderly Women

Ageing is characterized by a progressive decline in immune function known as immunosenescence (IS). While the causes of IS are likely to be multi-factorial, an age-associated accumulation of senescent T-cells and decreased naïve T-cell repertoire are key contributors to the phenomenon. On the other hand, there is a growing consensus that physical exercise may improve immune response in ageing. However, the optimum training modality required to obtain beneficial adaptations in older subjects is lacking. Therefore, we aimed to investigate the effects of exercise modality on T-cell phenotypes in older women. 100 women (aged ≥65 years) were randomized to either intensive strength training (80% of one-repetition maximum (1RM)), strength endurance training (SET, 40% 1RM), or control (stretching exercise) for 2-3 times/week during 6 weeks. The T-cell percentages and absolute counts were determined using flow cytometry and hematology analyzer. C-reactive protein was measured using immunonephelometry. We report for the first time that 6 weeks of SET significantly decreased the basal percentage and absolute counts of senescence-prone T-cells, which was positively related to the number of training sessions performed. Conceivably, training protocols with many repetitions - at a sufficiently high external resistance - might assist the reduction of senescence-prone T-cells in older women.