Ageing and endothelial progenitor cell release of proangiogenic cytokines

Aging-Related Endothelial Progenitor Cell Dysfunction and Its Association with IL-17 and IL-23 in HFmrEF Patients

Background

Aging is an independent risk factor for heart failure (HF), and endothelial progenitor cell (EPC) function decreases with aging. Here, we further investigated whether age has a detrimental effect on circulating EPC function in HF with mildly reduced ejection fraction (HFmrEF) and its relationship with systemic inflammation.

Methods

58 HFmrEF patients were recruited. The adhesive, migrative, and proliferative activities of circulating EPCs, MAGGIC scores, and plasma interleukin (IL)-17 and IL-23 levels of these patients were assessed.

Results

Older patients with HFmrEF had higher MAGGIC scores and lower circulating EPC adhesion, migration, and proliferation than younger patients. The similar tendency was observed in plasma IL-17 and IL-23 levels. The EPC functions were negatively associated with MAGGIC scores and plasma IL-17 or IL-23 levels.

Conclusions

In patients with HFmrEF, aging leads to attenuated circulating EPC function, which is correlated with disease severity and systemic inflammation. The present investigation provides some novel insights into the mechanism and intervention targets of HFmrEF.

Hypofunction of Circulating Endothelial Progenitor Cells and Aggravated Severity in Elderly Male Patients With Non-ST Segment Elevation Myocardial Infarction: Its Association With Systemic Inflammation

Background: Aging patients easily suffer from non-ST segment elevation myocardial infarction (NSTEMI). Our previous studies revealed declined function of endothelial progenitor cells (EPCs) in the elderly. However, the impact of aging on EPC function and severity in male NSTEMI patients and its possible mechanism is unclear until now.

Methods: We measured the circulating EPC function including migration, proliferation, and adhesion in aging or young male patients with NSTEMI. The GRACE and TIMI risk score were evaluated. Plasma levels of interleukin-6 (IL-6) and interleukin-17 (IL-17) were also detected in all patients.

Results: Compared with the young group, the old male patients with NSTEMI had higher GRACE score and TIMI score and decreased function of circulating EPCs. EPC function was negatively correlated with GRACE score and TIMI score. IL-6 and IL-17 level were higher in the old group than those in the young group. There was a significant negative correlation between EPC function and IL-6 or IL-17. Moreover, IL-6 and IL-17 positively correlated with GRACE and TIMI score. Age was positively related with GRACE or TIMI score and plasma level of IL-6 or IL-17, but inversely correlated with EPC function.

Conclusions: The current study firstly illustrates that the age-related decrement in EPC function is related to the severity of NSTEMI in male patients, which may be connected with systemic inflammation. These findings provide novel insights into the pathogenetic mechanism and intervention target of aging NSTEMI.

Potential Cellular and Biochemical Mechanisms of Exercise and Physical Activity on the Ageing Process

Exercise in young adults has been consistently shown to improve various aspects of physiological and psychological health but we are now realising the potential benefits of exercise with advancing age. Specifically, exercise improves cardiovascular, musculoskeletal, and metabolic health through reductions in oxidative stress, chronic low-grade inflammation and modulating cellular processes within a variety of tissues. In this this chapter we will discuss the effects of acute and chronic exercise on these processes and conditions in an ageing population, and how physical activity affects our vasculature, skeletal muscle function, our immune system, and cardiometabolic risk in older adults.

Endothelial Regenerative Capacity and Aging: Influence of Diet, Exercise and Obesity

Background:

The endothelium plays an important role in cardiovascular regulation, from blood flow to platelet aggregation, immune cell infiltration and demargination. A dysfunctional endo-thelium leads to the onset and progression of Cardiovascular Disease (CVD). The aging endothelium displays significant alterations in function, such as reduced vasomotor functions and reduced angio-genic capabilities. This could be partly due to elevated levels of oxidative stress and reduced endothe-lial cell turnover. Circulating angiogenic cells, such as Endothelial Progenitor Cells (EPCs) play a significant role in maintaining endothelial health and function, by supporting endothelial cell prolifera-tion, or via incorporation into the vasculature and differentiation into mature endothelial cells. Howev-er, these cells are reduced in number and function with age, which may contribute to the elevated CVD risk in this population. However, lifestyle factors, such as exercise, physical activity obesity, and dietary intake of omega-3 polyunsaturated fatty acids, nitrates, and antioxidants, significantly af-fect the number and function of these circulating angiogenic cells.

Conclusion:

This review will discuss the effects of advancing age on endothelial health and vascular regenerative capacity, as well as the influence of diet, exercise, and obesity on these cells, the mecha-nistic links and the subsequent impact on cardiovascular health

BM ageing: Implication for cell therapy with EPCs

The bone marrow (BM) is a well-recognized source of stem/progenitor cells for cell therapy in cardiovascular diseases (CVDs). Preclinical and clinical studies suggest that endothelial progenitor cells (EPCs) contribute to reparative process of vascular endothelium and participate in angiogenesis. As for all organs and cells across the lifespan, BM and EPCs are negatively impacted by ageing due to microenvironment modifications and EPC progressive dysfunctions. The encouraging results in terms of neovascularization observed in young animals after EPC administration were mitigated in aged patients treated for ischemic CVDs. The limited efficacy of EPC-based therapy in clinical setting might be ascribed at least partly to ageing. In this review, we comprehensively discussed the age-related changes of BM and EPCs and their implication for cardiovascular cell-therapies. Finally, we examined alternative approaches under investigation to enhance EPC potency.

Vascular Ageing and Exercise: Focus on Cellular Reparative Processes

Ageing is associated with an increased risk of developing noncommunicable diseases (NCDs), such as diabetes and cardiovascular disease (CVD). The increased risk can be attributable to increased prolonged exposure to oxidative stress. Often, CVD is preceded by endothelial dysfunction, which carries with it a proatherothrombotic phenotype. Endothelial senescence and reduced production and release of nitric oxide (NO) are associated with “vascular ageing” and are often accompanied by a reduced ability for the body to repair vascular damage, termed “reendothelialization.” Exercise has been repeatedly shown to confer protection against CVD and diabetes risk and incidence. Regular exercise promotes endothelial function and can prevent endothelial senescence, often through a reduction in oxidative stress. Recently, endothelial precursors, endothelial progenitor cells (EPC), have been shown to repair damaged endothelium, and reduced circulating number and/or function of these cells is associated with ageing. Exercise can modulate both number and function of these cells to promote endothelial homeostasis. In this review we look at the effects of advancing age on the endothelium and these endothelial precursors and how exercise appears to offset this “vascular ageing” process.

Chronic heart failure and aging - effects of exercise training on endothelial function and mechanisms of endothelial regeneration: Results from the Leipzig Exercise Intervention in Chronic heart failure and Aging (LEICA) study

BACKGROUND

A reduction in number and function of endothelial progenitor cells (EPCs) occurs in both physiologic aging and chronic heart failure (CHF). We assessed whether disease and aging have additive effects on EPCs or whether beneficial effects of exercise training are diminished in old age.

METHODS

We randomized 60 patients with stable CHF and 60 referent controls to a training or a control group. To detect possible aging effects we included subjects below 55 (young) and above 65 years (older). Subjects in the training group exercised four times daily at 60% to 70% of VO2max for four weeks under supervision. At baseline and after the intervention the number and function of EPCs were assessed.

RESULTS

As compared with young referent controls, older referent controls showed at baseline a reduced EPC number (young: 190 ± 37 CD34/KDR positive cells/ml blood; older: 131 ± 26 CD34/KDR positive cells/ml blood; p < 0.05) and function (young: 230 ± 41 migrated cells/1000 plated cells; older: 185 ± 28 cells/1000 plated cells; p < 0.05). In young and older CHF patients EPC-number (young: 85 ± 21 CD34/KDR positive cells/ml blood; older: 78 ± 20 CD34/KDR positive cells/ml blood) and EPC-function (young: 113 ± 26 cells/1000 plated cells; older: 120 ± 27 cells/1000 plated cells) were impaired. As a result of exercise training, EPC function improved by 24% in older referent controls (p < 0.05), while it remained unchanged in young training referent controls and controls respectively. In young and older patients with CHF four weeks of exercise training resulted in a significant improvement in EPC numbers and EPC function (young: number +66% function +43%; p < 0.05; older: number +69% function +36%; p < 0.05). These results were accompanied by a significant increase in flow mediated dilatation in the training groups of young/older CHF patients and in older referent controls.

CONCLUSIONS

Four weeks of exercise training are effective in improving EPC number and EPC function in CHF patients. These training effects were not impaired among older patients, emphasizing the potentials of rehabilitation interventions in a patient group where CHF has a high prevalence.

Changes in endothelial microparticles and endothelial progenitor cells in obese patients in response to surgical stress

BACKGROUND

Obese patients undergoing surgery are at increased risk of intraoperative and postoperative cardiovascular complications. The present study was designed to study the changes in endothelial microparticles, endothelial progenitor cells, and adipokines in obese patients in response to limb ischemia during knee surgery.

METHODS

This prospective study included seventy-four patients who underwent total knee arthroplasty. Patients were stratified in tertiles according to their body mass index. Flow cytometry was used for quantification and characterization of endothelial microparticles, endothelial progenitor cells, and adipokines. ELISA (enzyme-linked immunosorbent assay) was used to measure the adiponectin level.

RESULTS

The number of endothelial microparticles was greater in obese compared with nonobese patients. The number of endothelial microparticles increased further immediately after surgery in all tertiles. Three days after surgery, endothelial microparticles returned to the basal preoperative level except in the most obese patients. The percentage of endothelial progenitor cells was lower in obese patients. Concentrations of adipokines increased after surgery, but the increase was more accentuated in obese patients.

CONCLUSIONS

Obese patients present with a high number of endothelial microparticles, a low number of endothelial progenitor cells, and high levels of adipokines, with further increases in adipokines after surgery, suggesting an inflammatory condition that worsens after surgery and may affect endothelial repair.

Influence of elevated levels of C-reactive protein on circulating endothelial progenitor cell function

In vitro, C-reactive protein (CRP) impairs endothelial progenitor cell (EPC) function; however, the influence of CRP on EPCs in vivo is unclear. We determined whether EPC function is impaired in adults with elevated plasma CRP concentrations, independent of other risk factors. EPCs were harvested from 75 adults (43 males, 32 females): 25 with low CRP (<1.0 mg/L); 25 with moderate CRP (1.0-3.0 mg/L); and 25 with high CRP (>3.0 mg/L). The capacity of EPCs to form colonies (colony assay), migrate (Boyden chamber), release angiogenic growth factor (ELISA) and resist apoptosis (active caspase-3) was determined. There were no significant differences between the CRP groups in EPC colony formation (CFU), migration (AU) or the ability to release vascular endothelial growth factor (VEGF; pg/mL): low (13 ± 3 CFU; 1255 ± 100 AU; 126 ± 24 pg/mL); moderate (11 ± 3 CFU; 1137 ± 85 AU; 97 ± 14 pg/mL); and high (13 ± 4 CFU; 1071 ± 80 AU; 119 ± 22 pg/mL) CRP. Staurosporine-stimulated activation of caspase-3 was also similar between the low (2.3 ± 0.2 ng/mL), moderate (2.1 ± 0.3 ng/mL), and high (2.2 ± 0.2 ng/mL) CRP groups. These results indicate that elevations in plasma CRP are not associated with impaired EPC function. EPC dysfunction may not play a role in CRP-related cardiovascular risk.

Age-related decline in reendothelialization capacity of human endothelial progenitor cells is restored by shear stress

Aging is associated with dysfunction of endothelial progenitor cells (EPCs), and shear stress has a beneficial impact on EPC function; however, the effects of aging and shear stress on the endothelial repair capacity of EPCs after arterial injury have not been reported. Here we investigated the influence of aging and shear stress on the reendothelialization capacity of human EPCs and the related molecular mechanism. Compared with EPCs isolated from young subjects, EPCs from the elderly displayed an impaired migration and adhesion in vitro and demonstrated a significantly reduced reendothelialization capacity in vivo after transplantation into nude mice with carotid artery denudation injury. Shear stress pretreatment enhances the migration, adhesion, and reendothelialization capacity in both young and elderly EPCs; however, it was to a greater extent in EPCs from the elderly. Although basal CXC chemokine receptor 4 (CXCR4) expression was similar in EPCs from the 2 age groups, the stromal cell derived factor 1-induced CXCR4 and Janus kinase 2 phosphorylations were much lower in the elderly than in young EPCs. Shear stress treatment upregulated CXCR4 expression and phosphorylation and, importantly, restored the stromal cell-derived factor 1/CXCR4-dependent Janus kinase 2 phosphorylation in the elderly EPCs. Furthermore, short hairpin RNA-mediated knockdown of CXCR4 expression or pretreatment with Janus kinase 2 inhibitor diminished the enhancement in the migration, adhesion, and reendothelialization capacity of the elderly EPCs from shear stress treatments. Thus, our study demonstrates that upregulation of the CXCR4/Janus kinase 2 pathway by shear stress contributes to the enhanced reendothelialization capacity of EPCs from elderly men.