The immune system in the elderly: a fair fight against diseases?

Antiaging effects of dietary supplements and natural products

Aging is an inevitable process influenced by genetics, lifestyles, and environments. With the rapid social and economic development in recent decades, the proportion of the elderly has increased rapidly worldwide, and many aging-related diseases have shown an upward trend, including nervous system diseases, cardiovascular diseases, metabolic diseases, and cancer. The rising burden of aging-related diseases has become an urgent global health challenge and requires immediate attention and solutions. Natural products have been used for a long time to treat various human diseases. The primary cellular pathways that mediate the longevity-extending effects of natural products involve nutrient-sensing pathways. Among them, the sirtuin, AMP-activated protein kinase, mammalian target of rapamycin, p53, and insulin/insulin-like growth factor-1 signaling pathways are most widely studied. Several studies have reviewed the effects of individual natural compounds on aging and aging-related diseases along with the underlying mechanisms. Natural products from food sources, such as polyphenols, saponins, alkaloids, and polysaccharides, are classified as antiaging compounds that promote health and prolong life via various mechanisms. In this article, we have reviewed several recently identified natural products with potential antiaging properties and have highlighted their cellular and molecular mechanisms. The discovery and use of dietary supplements and natural products that can prevent and treat multiple aging-related diseases in humans will be beneficial. Thus, this review provides theoretical background for existing dietary supplements and natural products as potential antiaging agents.

Effect of seaweed (Ecklonia maxima) on apparent nutrient digestibility, growth performance, and physiological and meat quality parameters in Boschveld cockerels

Despite being touted as a rich source of nutrients and functional bioactive compounds, the amount of brown seaweed (Ecklonia maxima) that can be included in diets of Boschveld indigenous chickens is unknown. This study, therefore, investigated the effect of feeding graded levels of brown seaweed meal (BSM) on apparent nutrient digestibility, growth performance, and physiological and meat quality parameters in Boschveld cockerels. A total of 225, five-wk-old Boschveld cockerels (316.4 ± 23.01 g live weight) were raised on 5 isoenergetic and isonitrogenous experimental diets formulated by incorporating BSM in a standard grower diet at a concentration of 0 (BSM0), 20 (BSM2), 40 (BSM4), 60 (BSM6), and 80 g/kg (BSM8). Feeding graded levels of dietary BSM induced neither quadratic nor linear effects (P > 0.05) on apparent nutrient digestibility, growth performance, hematological parameters, and meat quality characteristics in Boschveld cockerels. However, it resulted in linear increases for overall feed intake (R² = 0.397; P = 0.021), ceca weight (R² = 0.417; P = 0.013), duodenum length (R² = 0.537; P = 0.04), and small intestine length (R² = 0.305; P = 0.041). Negative quadratic responses were recorded for alanine aminotransferase (R² = 0.530; P = 0.0009) and ileum length (R² = 0.457; P = 0.045) as BSM levels increased. In conclusion, dietary inclusion of BSM improved feed intake and some internal organ sizes, altered alanine transaminase levels, but had no significant effect on apparent nutrient digestibility, growth performance, and carcass and meat quality attributes of Boschveld indigenous cockerels.

Effect of dietary red grape pomace on growth performance, hematology, serum biochemistry, and meat quality parameters in Hy-line Silver Brown cockerels

Red grape (Vitis vinifera L.) pomace’s (RGP) beneficial bioactive compounds could improve growth and meat quality traits in chickens and thus valorize RGP waste that is usually disposed in landfills to the detriment of the environment. This study investigated the effect of RGP inclusion in diets of Hy-line Silver Brown cockerels on physiological and meat quality responses. Five isonitrogenous and isocaloric diets were formulated by mixing a standard grower diet with RGP at 0 (G0), 15 (G15), 30 (G30), 45 (G45) and 60 g/kg (G60). A total of 250, 5-week-old cockerels (304.6 ± 6.57 g live-weight) were evenly allocated to 25 pens replicated 5 times per experimental diet. No linear and quadratic trends (P > 0.05) were observed for overall feed intake, body weight gain, feed conversion ratio, and meat quality traits as dietary RGP levels increased. Erythrocytes linearly decreased (P < 0.05), whereas mean corpuscular hemoglobin and urea linearly increased (P < 0.05) with RGP levels. There were significant quadratic effects for glucose, phosphorus, total protein, albumin, globulin, and cholesterol, from which a maximum RGP inclusion level was calculated to be 43 g/kg. In conclusion, dietary red grape pomace had no adverse effect on physiological parameters and meat quality traits of Hy-line Silver Brown cockerels. However, including red grape pomace beyond 43 g/kg could compromise serum biochemical parameters of the birds.

Anthocyanidin Extract from Summer-black-grape Affects the Expression of Ki-67 in Testis, Ovary of D-Galactose-induced Aging Mice

The aim of this work was to analyze the expression of Ki-67 in ovary, testis of aging mice with anthocyanidin extract from Summer-black-grape. ICR mice (the aging group and the anthocyanidin-groups (50 mg/kg/D-group, 75 mg/kg/D-group and 100 mg/kg/D-group) were employed to evaluate the effect of grape anthocyanidin on reproductive system. The results showed that the anthocyanidin had strong scavenging ability for free radicals, the level of oxidation in serum of mice treated with anthocyanidin was low, and the pathological changes were not obvious. In the anthocyanidin group, the Ki-67 positive particles in the testis and ovary tissue were significantly decreased. The anthocyanidin of Summer-black-grape reduces the expression of Ki-67 protein in the testis or ovary of aging mice. In gonadal cells of aging mice, the anthocyanidin were shown protective effect in the proliferation.

Peripheral antibody concentrations are associated with highly differentiated T cells and inflammatory processes in the human bone marrow

Background

Antigen-experienced immune cells migrate back to the bone marrow (BM), where they are maintained in BM survival niches for an extended period. The composition of T cell subpopulations in the BM changes with age, leading to an accumulation of highly differentiated T cells and a loss of naïve T cells. While innate immune cells are also affected by age, little is known about interactions between different adaptive immune cell populations maintained in the BM. In this study, the phenotype and function of innate and adaptive immune cells isolated from human BM and peripheral blood (PB) was analysed in detail using flow cytometry, to determine if the accumulation of highly differentiated T and B cells, supported by the BM niches, limits the maintenance of other immune cells, or affects their functions such as providing protective antibody concentrations.

Results

Total T cells increase in the BM with age, as do highly differentiated CD8⁺ T cells which no longer express the co-stimulatory molecule CD28, while natural killer T (NKT) cells, monocytes, B cells, and naïve CD8⁺ T cells all decrease in the BM with age. A negative correlation of total T cells with B cells was observed in the BM. The percentage of B cells in the BM negatively correlated with highly differentiated CD8⁺CD28⁻ T cells, replicative-senescent CD8⁺CD57⁺ T cells, as well as the CD8⁺CD28⁻CD57⁺ population. Similar correlations were seen between B cells and the frequency of highly differentiated T cells producing pro-inflammatory molecules in the BM. Interestingly, plasma concentrations of diphtheria-specific antibodies negatively correlated with highly differentiated CD8⁺CD57⁺ T cells as well as with exhausted central memory CD8⁺ and CD4⁺ T cells in the BM. A negative impact on diphtheria-specific antibodies was also observed for CD8⁺ T cells expressing senescence associated genes such as the cell cycle regulator p21 (CDKN1A), KLRG-1, and elevated levels of reactive oxygen species (ROS).

Conclusion

Our data suggest that the accumulation and maintenance of highly differentiated, senescent, and exhausted T cells in the BM, particularly in old age, may interfere with the survival of other cell populations resident in the BM such as monocytes and B cells, leading to reduced peripheral diphtheria antibody concentrations as a result. These findings further highlight the importance of the BM in the long-term maintenance of immunological memory.

Electronic supplementary material

The online version of this article (10.1186/s12979-019-0161-z) contains supplementary material, which is available to authorized users.

Human microbiota in aging and infection: A review

In most developed countries, ageing of the population started more than a century ago and it seems to be emerged in a wide range of developing countries as well. Moreover, research into ageing has moved forward in extremely rapidly rhythms nowadays, and the scientific area is of great interest, as implications for nearly all sectors of society, including work, social, economic features, in addition to nutrition and health issues which are involved. The fragile elder population is affected and experienced more frequently infections than the younger population. Infections in elderly patients are of major medical importance because of hormonal changes, increased production of pro-inflammatory cytokines and chemokines, abnormalities of the telomeres which could cause a dysfunction of the immune system called immunosenescence and malnutrition.

Distribution and factors associated with salivary secretory leukocyte protease inhibitor concentrations

OBJECTIVES

This cross-sectional study examined the distribution and correlates of salivary secretory leukocyte protease inhibitor (SLPI) concentrations within a multinational cohort of men.

METHODS

Extracellular SLPI was measured in oral gargle cell supernatants of 378 men from three countries using an ELISA-based assay. Risk factor data were collected by a questionnaire. Factors associated with SLPI were assessed using linear and logistic regression for continuous and categorical SLPI, respectively.

RESULTS

Among men aged 18-73 years, the median SLPI concentration was 492.0 ng ml^-1 (range: 2.3-1919.9). In multivariable modeling, men in Brazil and younger men (18-30 years) were more likely to have higher levels of SLPI [adjusted odds ratio (aOR) 3.84; 95% confidence interval (CI): 1.94-7.59, and aOR 3.84; 95% CI: 1.98-7.43, respectively]. Men with a self-reported sexually transmitted diseases diagnosis in the past 6 months were more likely to have higher SLPI levels (aOR 2.98; 95% CI: 1.1-7.83) and men reporting bleeding/swollen gums were less likely to have higher SLPI (aOR 0.34; 95% CI: 0.15-0.79). Similar results were observed for linear regression models.

CONCLUSIONS

Secretory leukocyte protease inhibitor concentrations varied significantly by country and decreased with increasing age. The interaction between SLPI, modifiable factors, and oral infections that influence cancer risk warrants further investigation.

Intracellular signalling pathways: targets to reverse immunosenescence

Ageing is a very complex process, the result of the dysregulation of multiple systems interacting in many ways. A prominent change occurring with ageing is related to the architecture and functioning of the immune system, viewed commonly as detrimental and termed 'immunosenescence'. However, age-associated changes may also lead to increased function in certain respects, which can be viewed as adaptive. None the less, on balance it is well-recognized that immunosenescence is accompanied by the low-grade inflammation observed commonly in elderly people, which has been dubbed 'inflamm-ageing'. The exact cause and significance of all these changes is not clear, but there is a consensus that they are related to the occurrence of chronic non-infectious age-associated disease, as well as increased susceptibility to infections. Alterations to immune cell signalling may be a prominent cause of malfunctioning immunity. Emerging attempts to reverse immunosenescence have recently targeted the signalling pathways in various different cell types of the immune system. Here, we review and discuss alterations in the signalling pathways of immune cells with ageing and consider current targets and means to modulate altered functions. We discuss the potential dangers as well as the benefits of these interventions, and consider future approaches to this problem.

Anti-Apoptotic and Pro-Survival Effect of Alpinate Oxyphyllae Fructus (AOF) in a d-Galactose-Induced Aging Heart

Aging, a natural biological/physiological phenomenon, is accelerated by reactive oxygen species (ROS) accumulation and identified by a progressive decrease in physiological function. Several studies have shown a positive relationship between aging and chronic heart failure (HF). Cardiac apoptosis was found in age-related diseases. We used a traditional Chinese medicine, Alpinate Oxyphyllae Fructus (AOF), to evaluate its effect on cardiac anti-apoptosis and pro-survival. Male eight-week-old Sprague–Dawley (SD) rats were segregated into five groups: normal control group (NC), d-Galactose-Induced aging group (Aging), and AOF of 50 (AL (AOF low)), 100 (AM (AOF medium)), 150 (AH (AOF high)) mg/kg/day. After eight weeks, hearts were measured by an Hematoxylin–Eosin (H&E) stain, Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-assays and Western blotting. The experimental results show that the cardiomyocyte apoptotic pathway protein expression increased in the d-Galactose-Induced aging groups, with dose-dependent inhibition in the AOF treatment group (AL, AM, and AH). Moreover, the expression of the pro-survival p-Akt (protein kinase B (Akt)), Bcl-2 (B-cell lymphoma 2), anti-apoptotic protein (Bcl-xL) protein decreased significantly in the d-Galactose-induced aging group, with increased performance in the AOF treatment group with levels of p-IGFIR and p-PI3K (Phosphatidylinositol-3′ kinase (PI3K)) to increase by dosage and compensatory performance. On the other hand, the protein of the Sirtuin 1 (SIRT1) pathway expression decreased in the aging groups and showed improvement in the AOF treatment group. Our results suggest that AOF strongly works against ROS-induced aging heart problems.

Adipose-Derived Mesenchymal Stem Cells Restore Impaired Mucosal Immune Responses in Aged Mice

It has been shown that adipose-derived mesenchymal stem cells (AMSCs) can differentiate into adipocytes, chondrocytes and osteoblasts. Several clinical trials have shown the ability of AMSCs to regenerate these differentiated cell types. Age-associated dysregulation of the gastrointestinal (GI) immune system has been well documented. Our previous studies showed that impaired mucosal immunity in the GI tract occurs earlier during agingthan is seen in the systemic compartment. In this study, we examined the potential of AMSCs to restore the GI mucosal immune system in aged mice. Aged (>18 mo old) mice were adoptively transferred with AMSCs. Two weeks later, mice were orally immunized with ovalbumin (OVA) plus cholera toxin (CT) three times at weekly intervals. Seven days after the final immunization, when fecal extract samples and plasma were subjected to OVA- and CT-B-specific ELISA, elevated levels of mucosal secretory IgA (SIgA) and plasma IgG antibody (Ab) responses were noted in aged mouse recipients. Similar results were also seen aged mice which received AMSCs at one year of age. When cytokine production was examined, OVA-stimulated Peyer's patch CD4+ T cells produced increased levels of IL-4. Further, CD4+ T cells from the lamina propria revealed elevated levels of IL-4 and IFN-γ production. In contrast, aged mice without AMSC transfer showed essentially no OVA- or CT-B-specific mucosal SIgA or plasma IgG Ab or cytokine responses. Of importance, fecal extracts from AMSC transferred aged mice showed neutralization activity to CT intoxication. These results suggest that AMSCs can restore impaired mucosal immunity in the GI tract of aged mice.

Laparoscopic cholecystectomy in elderly patients: an evaluation of immunity

OBJECTIVE

We sought to investigate the impact of laparoscopic cholecystectomy (LC) on the inflammatory response and immunological function of elderly patients compared with that on the younger ones.

METHODS

Between June 2012 and June 2013, this prospective study investigated a total of 112 patients having the surgery of LC due to symptomatic cholelithiasis or polyps, among whom 52 were elderly patients with the age beyond 65 years old and the remaining 60 were younger than the age. Peripheral venous blood samples were taken from these patients prior to surgery and on post-operative days 1, 3 and 7, respectively. The perioperative clinical outcomes and immunological function results were analyzed and compared between the two groups divided by age.

RESULTS

The demographics of the two groups did not differ except for the age. Surgical trauma seemed more serious for elderly patients as illustrated by the longer operating time, hospital stay and more quantity of patients got complication. Both groups indicated changes in inflammatory and immune aspects. Compared with the younger ones, elderly patients showed less quantity of preoperative basic immune cells, delayed immune responses after the surgical trauma of LC and hyporeactivity of inflammatory response when accepting LC.

CONCLUSIONS

An examination of the inflammatory reaction and immune response after LC demonstrated that there are significant differences observed in two groups divided by age. Further studies with more samples are required to determine the exact relationship of perioperative immune change and higher adverse outcome rate of aged people.

Slipping through the Cracks: Linking Low Immune Function and Intestinal Bacterial Imbalance to the Etiology of Rheumatoid Arthritis

Autoimmune diseases (ADs) are considered to be caused by the host immune system which attacks and destroys its own tissue by mistake. A widely accepted hypothesis to explain the pathogenic mechanism of ADs is “molecular mimicry,” which states that antibodies against an infectious agent cross-react with a self-antigen sharing an identical or similar antigenic epitope. However, this hypothesis was most likely established based on misleading antibody assay data largely influenced by intense false positive reactions involved in immunoassay systems. Thus reinvestigation of this hypothesis using an appropriate blocking agent capable of eliminating all types of nonspecific reactions and proper assay design is strongly encouraged. In this review, we discuss the possibility that low immune function may be the fundamental, common defect in ADs, which increases the susceptibility to potential disease causative pathogens located in the gastrointestinal tract (GI), such as bacteria and their components or dietary components. In addition to these exogenous agents, aberrations in the host's physical condition may disrupt the host defense system, which is tightly orchestrated by “immune function,” “mucosal barrier function,” and “intestinal bacterial balance.” These disturbances may initiate a downward spiral, which can lead to chronic health problems that will evolve to an autoimmune disorder.

Natural compounds and aging: between autophagy and inflammasome

Aging, a natural physiological process, is characterized by a progressive loss of physiological integrity. Loss of cellular homeostasis in the aging process results from different sources, including changes in genes, cell imbalance, and dysregulation of the host-defense systems. Innate immunity dysfunctions during aging are connected with several human pathologies, including metabolic disorders and cardiovascular diseases. Recent studies have clearly indicated that the decline in autophagic capacity that accompanies aging results in the accumulation of dysfunctional mitochondria, reactive oxygen species (ROS) production, and further process dysfunction of the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome activation in the macrophages, which produce the proinflammatory cytokines. These factors impair cellular housekeeping and expose cells to higher risk in many age-related diseases, such as atherosclerosis and type 2 diabetes. In this review, we investigated the relationship between dysregulation of the inflammasome activation and perturbed autophagy with aging as well as the possible molecular mechanisms. We also summarized the natural compounds from food intake, which have potential to reduce the inflammasome activation and enhance autophagy and can further improve the age-related diseases discussed in this paper.

Immunomodulatory role of high-density lipoproteins: impact on immunosenescence

Natural aging is accompanied by a dysregulation of the host immune response that has well-known clinical consequences but poorly defined underlying causes. It has previously been reported that advancing age is associated with an increase in membrane cholesterol level in T cells. The aim of this study was to investigate whether high-density lipoprotein (HDL) can modulate the age-related accumulation of membrane cholesterol in T cells and impact on their subsequent responsiveness. Our data reveal that cholesterol metabolism, influx, and efflux are altered in T cells with aging, which may in part explain the increase in membrane cholesterol level observed in T cells in elderly individuals. HDL was unable to promote reverse cholesterol transport in T cells from elderly subjects with the same efficiency as was observed in T cells from young subjects besides unchanged ABCA-1 and SR-BI expressions. HDL exhibited a short-acting co-stimulatory effect by enhancing T cell production of interleukin-2 (IL-2). Moreover, HDL from healthy normolipemic individuals exerted differential effects on T cell proliferation that depended on the age of the HDL donor. Finally, HDL modulated TCR/CD28 activation by inducing sustained signaling through pLck, pERK, and pAkt. These data suggest that HDL has immunomodulatory effects on T cells that are influenced by age.

Cellular signaling in the aging immune system

Causes for immunosenescence and inflamm-aging have to be established. Efficient function of the immune system requires homeostatic regulation from receptor recognition of antigenic challenge to cell responses and adaptation to its changing environment. It is reasonable to assume that one of the most important molecular causes of immunosenescence is alteration in the regulation of signaling pathways. Indeed, alterations in feed-forward and negative feedback (inhibitory) signaling have been highlighted in all cells involved in the immune response including short-lived (neutrophils) and long-lived (T lymphocytes) cells. These dysregulations tip the balance in favor of altered (less efficient) function of the immune system. In this review, we summarize our knowledge on signal transduction changes in the aging immune system and propose a unifying mechanism as one of the causes of immunosenescence. Modulation of these pathways with aging represents a major challenge to restore the immune response to functional levels.

From "truly naïve" to "exhausted senescent" T cells: when markers predict functionality

The study of T cell biology has been accelerated by substantial progress at the technological level, particularly through the continuing advancement of flow cytometry. The conventional approach of observing T cells as either T helper or T cytotoxic is overly simplistic and does not allow investigators to clearly identify immune mechanisms or alterations in physiological processes that impact on clinical outcomes. The complexity of T cell sub-populations, as we understand them today, combined with the immunological and functional diversity of these subsets represent significant complications for the study of T cell biology. In this article, we review the use of classical markers in delineating T cell sub-populations, from "truly naïve" T cells (recent thymic emigrants with no proliferative history) to "exhausted senescent" T cells (poorly proliferative cells that display severe functional abnormalities) wherein the different phenotypes of these populations reflect their disparate functionalities. In addition, since persistent infections and chronological aging have been shown to be associated with significant alterations in human T cell distribution and function, we also discuss age-associated and cytomegalovirus-driven alterations in the expression of key subset markers.