Immunomodulatory effect of in vitro calcitriol in fit and frail elderly

Counteracting Immunosenescence-Which Therapeutic Strategies Are Promising?

Aging attenuates the overall responsiveness of the immune system to eradicate pathogens. The increased production of pro-inflammatory cytokines by innate immune cells under basal conditions, termed inflammaging, contributes to impaired innate immune responsiveness towards pathogen-mediated stimulation and limits antigen-presenting activity. Adaptive immune responses are attenuated as well due to lowered numbers of naïve lymphocytes and their impaired responsiveness towards antigen-specific stimulation. Additionally, the numbers of immunoregulatory cell types, comprising regulatory T cells and myeloid-derived suppressor cells, that inhibit the activity of innate and adaptive immune cells are elevated. This review aims to summarize our knowledge on the cellular and molecular causes of immunosenescence while also taking into account senescence effects that constitute immune evasion mechanisms in the case of chronic viral infections and cancer. For tumor therapy numerous nanoformulated drugs have been developed to overcome poor solubility of compounds and to enable cell-directed delivery in order to restore immune functions, e.g., by addressing dysregulated signaling pathways. Further, nanovaccines which efficiently address antigen-presenting cells to mount sustained anti-tumor immune responses have been clinically evaluated. Further, senolytics that selectively deplete senescent cells are being tested in a number of clinical trials. Here we discuss the potential use of such drugs to improve anti-aging therapy.

Vitamin D, Cellular Senescence and Chronic Kidney Diseases: What Is Missing in the Equation?

As life expectancy increases in many countries, the prevalence of age-related diseases also rises. Among these conditions, chronic kidney disease is predicted to become the second cause of death in some countries before the end of the century. An important problem with kidney diseases is the lack of biomarkers to detect early damage or to predict the progression to renal failure. In addition, current treatments only retard kidney disease progression, and better tools are needed. Preclinical research has shown the involvement of the activation of cellular senescence-related mechanisms in natural aging and kidney injury. Intensive research is searching for novel treatments for kidney diseases as well as for anti-aging therapies. In this sense, many experimental shreds of evidence support that treatment with vitamin D or its analogs can exert pleiotropic protective effects in kidney injury. Moreover, vitamin D deficiency has been described in patients with kidney diseases. Here, we review recent evidence about the relationship between vitamin D and kidney diseases, explaining the underlying mechanisms of the effect of vitamin D actions, with particular attention to the modulation of cellular senescence mechanisms.

Nutrition, Immunosenescence, and Infectious Disease: An Overview of the Scientific Evidence on Micronutrients and on Modulation of the Gut Microbiota

The immune system is key to host defense against pathogenic organisms. Aging is associated with changes in the immune system, with a decline in protective components (immunosenescence), increasing susceptibility to infectious disease, and a chronic elevation in low-grade inflammation (inflammaging), increasing the risk of multiple noncommunicable diseases. Nutrition is a determinant of immune cell function and of the gut microbiota. In turn, the gut microbiota shapes and controls the immune and inflammatory responses. Many older people show changes in the gut microbiota. Age-related changes in immune competence, low-grade inflammation, and gut dysbiosis may be interlinked and may relate, at least in part, to age-related changes in nutrition. A number of micronutrients (vitamins C, D, and E and zinc and selenium) play roles in supporting the function of many immune cell types. Some trials report that providing these micronutrients as individual supplements can reverse immune deficits in older people and/or in those with insufficient intakes. There is inconsistent evidence that this will reduce the risk or severity of infections including respiratory infections. Probiotic, prebiotic, or synbiotic strategies that modulate the gut microbiota, especially by promoting the colonization of lactobacilli and bifidobacteria, have been demonstrated to modulate some immune and inflammatory biomarkers in older people and, in some cases, to reduce the risk and severity of gastrointestinal and respiratory infections, although, again, the evidence is inconsistent. Further research with well-designed and well-powered trials in at-risk older populations is required to be more certain about the role of micronutrients and of strategies that modify the gut microbiota-host relationship in protecting against infection, especially respiratory infection.

Inflammatory biomarkers in older adults with frailty: a systematic review and meta-analysis of cross-sectional studies

BACKGROUND

Systemic chronic inflammation has been proposed as an essential mediating factor in frailty, and several studies tested its relationship with frailty. However, the issue is still controversial.

OBJECTIVES

We identified observational studies and pooled their results to assess whether abnormal expression of inflammatory biomarkers is present in the blood of older adults with frailty.

METHODS

We conducted a systematic search on the Medline, Embase, and Web of Science database from inception to 1st September 2021. The quality of included studies was assessed using the JBI Critical Appraisal Checklist for Analytical Cross-Sectional Studies (JBI-MAStARI). Study heterogeneity was assessed with the Cochran Q test and I² statistic. Pooled estimates were obtained through random-effect models. Sensitivity analyses were conducted by excluding one of the studies. Egger's regression test and observation of funnel plots were used to detect small-study effects and publication bias. PROSPERO registration: CRD42020172853.

RESULT

A total of 53 cross-sectional studies corresponding to 56 independent study populations were included in this analysis. There were 31 study populations with three frailty categories (3144 frailty, 14,023 pre-frailty, 10,989 robust) and 25 study populations with two frailty categories (2576 frailty, 8368 non-frailty). This meta-analysis performed pooled analyses for the inflammatory biomarker leukocyte, lymphocytes, CRP, IL-6, IL-10, and TNF-α. Older adults with frailty had lower lymphocytes and higher interleukin-6 (IL-6), C-reactive protein (CRP) and tumor necrosis factor-alpha (TNF-α) levels compared with the control group. However, there was no significant difference in leukocyte and IL-10 levels in the two groups.

CONCLUSIONS

These findings suggest that peripheral inflammatory biomarkers lymphocytes, IL-6, CRP, and TNF-α are related to frailty status. Our findings are not conclusive regarding the causal relationship between chronic inflammation and frailty, so the development of further longitudinal and well-designed studies focused on this is necessary.