Bone-marrow derived progenitor cells are associated with psychosocial determinants of health after controlling for classical biological and behavioral cardiovascular risk factors

Allostatic Load Measurement: A Systematic Review of Reviews, Database Inventory, and Considerations for Neighborhood Research

BACKGROUND

Neighborhoods are critical to understanding how environments influence health outcomes. Prolonged environmental stressors, such as a lack of green spaces and neighborhood socioeconomic disadvantage, have been associated with higher allostatic load levels. Since allostatic load levels experienced earlier in life have stronger associations with mortality risk, neighborhoods may be uniquely suited to monitor and mitigate the impacts of environmental stressors. Researchers often study allostatic load in neighborhoods by utilizing administrative boundaries within publicly accessible databases as proxies for neighborhoods.

METHODS

This systematic review of reviews aims to identify commonly used biomarkers in the measurement of allostatic load, compare measurement approaches, inventory databases to study allostatic load, and spotlight considerations referenced in the literature where allostatic load is studied in neighborhoods. The review was conducted using the search term "allostatic load" in the MEDLINE, CINAHL, and PsychINFO databases. The search results were filtered to include reviews.

RESULTS

The search returned 499 articles after deduplication. Overall, 18 synthesis reviews met the inclusion criteria and were retained for extraction. The synthesis reviews analyzed represented 238 studies published from 1995 to 2020. The original ten biomarkers were most often used to measure allostatic load. More recently, body mass index and C-reactive protein have additionally been frequently used to measure allostatic load burden.

CONCLUSIONS

The scientific contributions of this study are that we have identified a clear gap in geographic considerations when studying allostatic load. The implication of this study is that we have highlighted geographic concepts when conducting neighborhood-level research using administrative databases as a neighborhood proxy and outlined emerging future trends that can enable future study of allostatic load in the neighborhood context.

Distinct CCL2, CCL5, CCL11, CCL27, IL-17, IL-6, BDNF serum profiles correlate to different job-stress outcomes

Chronic psychosocial stress at workplace is an important factor in the development of physical and mental illness. Objective biological measures of chronic stress are still lacking, but inflammatory response and growth factors are increasingly considered as potential stress biomarkers. Therefore, we investigated the relationship between psychophysical strain and serum levels of 48 chemokines, cytokines and growth factors measured using a multiplex immunoassay, and serum brain-derived neurotrophic factor (BDNF) measured by ELISA. Severity of psychophysical strain was scored in 115 healthy hospital workers using specific scales for anxiety, depression-like emotion, gastrointestinal or cardiac disturbances, and ergonomic dysfunction. Multivariate analysis revealed that higher anxiety scale scores were correlated with lower serum chemokine C-C motif ligand-2 (CCL2/MCP-1), chemokine C-C motif ligand-5 (CCL5/RANTES), chemokine C-C motif ligand-27 (CCL27/CTACK), chemokine C-C motif ligand-11 (CCL11/Eotaxin) and interleukin-6 (IL-6); gastrointestinal disturbances correlated with increased levels of interleukin-17 (IL-17) and reduced CCL11/Eotaxin, CCL27/CTACK and CCL2/MCP-1; while cardiac dysfunctions associate only to reduced CCL27/CTACK, and ergonomic dysfunction correlated with increased BDNF and reduced CCL11/Eotaxin and CCL5/RANTES. Thus, these 7 serum factors may provide a distinct signature for each different stress-related psychophysical outcome giving indications on individual vulnerabilities.

Chronic stress is associated with reduced circulating hematopoietic progenitor cell number: A maternal caregiving model

BACKGROUND

Chronic psychological stress is a risk factor for cardiovascular disease and mortality. Circulating hematopoietic progenitor cells (CPCs) maintain vascular homeostasis, correlate with preclinical atherosclerosis, and prospectively predict cardiovascular events. We hypothesize that (1) chronic caregiving stress is related to reduced CPC number, and (2) this may be explained in part by negative interactions within the family.

METHODS

We investigated levels of stress and CPCs in 68 healthy mothers - 31 of these had children with an autism spectrum disorder (M-ASD) and 37 had neurotypical children (M-NT). Participants provided fasting blood samples, and CD45⁺CD34⁺KDR⁺ and CD45⁺CD133⁺KDR⁺ CPCs were assayed by flow cytometry. We averaged the blom-transformed scores of both CPCs to create one index. Participants completed the perceived stress scale (PSS), the inventory for depressive symptoms (IDS), and reported on daily interactions with their children and partners, averaged over 7 nights.

RESULTS

M-ASD exhibited lower CPCs than M-NT (Cohen's d=0.83; p⩽0.01), controlling for age, BMI, and physical activity. Across the whole sample, positive interactions were related to higher CPCs, and negative interactions to lower CPCs (allp's<0.05). The adverse effects of group on CPCs were significantly mediated through negative interactions with the child (indirect β=-0.24, p⩽0.01). In the full model, greater age (β=-0.19, p=0.04), BMI (β=-0.18, p=0.04), and negative interactions with the child (β=-0.33, p<0.01) were independently associated with lower CPCs. M-ASD had a less healthy lipid profile (total cholesterol/HDL), which in turn, was associated with lower CPCs.

CONCLUSIONS

Chronic stress adversely impacts CPC number, an early-stage biomarker that predicts subclinical atherosclerosis and future CVD events, independent of traditional cardiovascular risk factors and inflammatory factors. Among maternal caregivers, child-related interpersonal stress appears to be a key psychological predictor of stress-related CVD risk.

The Beneficial Effects of Cardiac Rehabilitation on the Function and Levels of Endothelial Progenitor Cells

Cardiac rehabilitation (CR) is a comprehensive program, which mainly focusses on exercise training, disease evaluation, cardiovascular risk factors control, medication therapy, psychosocial intervention, and patient education. Although the beneficial properties of CR have been widely evidenced, its mechanism is still not completely clarified. To date, endothelial progenitor cells (EPCs) have been explored by emerging studies, and evidence has suggested that CR, especially exercise training, significantly increases the function and levels of EPCs, which is likely to elucidate the profiting mechanism of CR. Thus, this review summarises the potential relationship between CR and EPCs with an aim of providing novel directions for future CR research.

Measuring allostatic load in the workforce: a systematic review

The Allostatic Load Index (ALI) has been used to establish associations between stress and health-related outcomes. This review summarizes the measurement and methodological challenges of allostatic load in occupational settings. Databases of Medline, PubPsych, and Cochrane were searched to systematically explore studies measuring ALI in working adults following the PRISMA statement. Study characteristics, biomarkers and methods were tabulated. Methodological quality was evaluated using a standardized checklist. Sixteen articles (2003-2013) met the inclusion criteria, with a total of 39 (range 6-17) different variables used to calculate ALI. Substantial heterogeneity was observed in the number and type of biomarkers used, the analytic techniques applied and study quality. Particularly, primary mediators were not regularly included in ALI calculation. Consensus on methods to measure ALI in working populations is limited. Research should include longitudinal studies using multi-systemic variables to measure employees at risk for biological wear and tear.

Sympathetic predominance is associated with impaired endothelial progenitor cells and tunneling nanotubes in controlled-hypertensive patients

Early endothelial progenitor cells (early EPC) and late EPC are involved in endothelial repair and can rescue damaged endothelial cells by transferring organelles through tunneling nanotubes (TNT). In rodents, EPC mobilization from the bone marrow depends on sympathetic nervous system activity. Indirect evidence suggests a relation between autonomic derangements and human EPC mobilization. We aimed at testing whether hypertension-related autonomic imbalances are associated with EPC impairment. Thirty controlled-essential hypertensive patients [systolic blood pressure/diastolic blood pressure = 130(120-137)/85(61-88) mmHg; 81.8% male] and 20 healthy normotensive subjects [114(107-119)/75(64-79) mmHg; 80% male] were studied. Mononuclear cells were cultured on fibronectin- and collagen-coated dishes for early EPC and late EPC, respectively. Low (LF)- and high (HF)-frequency components of short-term heart rate variability were analyzed during a 5-min rest, an expiration/inspiration maneuver, and a Stroop color-word test. Modulations of cardiac sympathetic and parasympathetic activities were evaluated by LF/HF (%) and HF power (ms(2)), respectively. In controlled-hypertensive patients, the numbers of early EPC, early EPC that emitted TNT, late EPC, and late EPC that emitted TNT were 41, 77, 50, and 88% lower than in normotensive subjects (P < 0.008), respectively. In controlled-hypertensive patients, late EPC number was positively associated with cardiac parasympathetic reserve during the expiration/inspiration maneuver (rho = 0.45, P = 0.031) and early EPC with brachial flow-mediated dilation (rho = 0.655; P = 0.049); also, late TNT number was inversely related to cardiac sympathetic response during the stress test (rho = -0.426, P = 0.045). EPC exposure to epinephrine or norepinephrine showed negative dose-response relationships on cell adhesion to fibronectin and collagen; both catecholamines stimulated early EPC growth, but epinephrine inhibited late EPC growth. In controlled-hypertensive patients, sympathetic overactivity/parasympathetic underactivity were negatively associated with EPC, suggesting that reducing sympathetic/increasing parasympathetic activation might favor endothelial repair.

A transdisciplinary perspective of chronic stress in relation to psychopathology throughout life span development

The allostatic load (AL) model represents an interdisciplinary approach to comprehensively conceptualize and quantify chronic stress in relation to pathologies throughout the life cycle. This article first reviews the AL model, followed by interactions among early adversity, genetics, environmental toxins, as well as distinctions among sex, gender, and sex hormones as integral antecedents of AL. We next explore perspectives on severe mental illness, dementia, and caregiving as unique human models of AL that merit future investigations in the field of developmental psychopathology. A complimenting transdisciplinary perspective is applied throughout, whereby we argue that the AL model goes beyond traditional stress–disease theories toward the advancement of person-centered research and practice that promote not only physical health but also mental health.

The fruits of ones labor: Effort-reward imbalance but not job strain is related to heart rate variability across the day in 35-44-year-old workers

OBJECTIVE

Previous research has suggested that the association between work stress and heart disease is more pronounced in young than in old employees. Similar age specificity may apply to the relation between work stress and heart rate variability (HRV), but data on this issue is sparse. We aimed to assess the age-specificity of the work stress-HRV association in greater detail.

METHODS

We used cross-sectional data from an occupational cohort (n=591) from Germany. Work stress was assessed using the job content and the effort-reward-imbalance (ERI) questionnaires. HRV was recorded over 24 h and was divided into three periods of the day (work time, leisure time, sleep time). Partial correlation coefficients (PCCs) were calculated for four age groups (17-34, 35-44, 45-54, and 55-65 years). Further, multilevel growth curve models (GCM) were run to examine whether age may modify potential work stress-HRV associations in a non-linear fashion.

RESULTS

Job strain and HRV were unrelated in either analytical approach and this association was not modified by age. In contrast, using PCCs ERI was only related to HRV during work (PCC=-0.231, P<.01) and leisure time (PCC=-0.195, P<.05) in employees aged 35-44. Multilevel GCM models confirmed this finding.

CONCLUSION

The inverse association between work stress as measured by ERI and HRV appears to be most pronounced in workers aged 35-44. These findings may partly be explained by age-dependent HRV declines, age-related differences in career attitudes or increased susceptibility among those aged 35-44 due to facing multiple different stressors at the same time.

Current perspective of pathophysiological and interventional effects on endothelial progenitor cell biology: focus on PI3K/AKT/eNOS pathway

For more than a decade, endothelial progenitor cells (EPCs) have been implicated in cardiovascular homeostasis. EPCs are believed to reside within the bone marrow in close contact with surrounding stromal cells, and, under stimulation of pro-inflammatory cytokines, EPCs are mobilized out of the bone marrow. Hereafter circulating EPCs home to peripheral tissues, undergoing further proliferation and differentiation. Under certain pathophysiologic conditions this process seems to be blunted, resulting in a reduced capacity of EPCs to engage in vasculogenesis at sites of endothelial injury or tissue ischemia. In this review, we focus on the effects of traditional cardiovascular risk factors on EPC biology and we explore whether pharmacological, dietary and lifestyle interventions can favorably restore EPC mobilization, differentiation, homing and angiogenic properties. Because the PI3K/Akt/eNOS pathway plays a pivotal role in the process of EPC mobilization, migration and homing, we specifically emphasize the involvement of PI3K, Akt and eNOS in EPC biology under these different (patho)physiologic conditions. (Pre)clinically used drugs or lifestyle interventions that have been shown to ameliorate EPC biology are reviewed. These treatment strategies remain attractive targets to restore the regenerative capacity of EPCs in cardiovascular diseases.

Endothelial progenitor cells in vascular health: focus on lifestyle

Endothelial dysfunction, which is considered the functional equivalent of a disrupted balance between endothelial injury and repair, precedes overt atherosclerosis by many years. Although this phenomenon is part of the normal aging process, prevention of early and progressive endothelial dysfunction has become an important therapeutic target. Evidence has accumulated to show that endothelial progenitor cells (EPC), contribute substantially to preservation of a structurally and functionally intact endothelium. There has been considerable progress in our understanding of the various cell types that were in the past all covered by the term "EPC." EPC home to sites of endothelial injury and ischemia, where they proliferate, differentiate and integrate into the endothelial layer or exert a paracrine function by producing vascular growth factors. Although more emphasis has been put on the pharmacological approach of endothelial dysfunction, the effect of a healthy lifestyle, via mobilization and functional improvement of EPC, is increasingly recognized. This review will focus on successful lifestyle interventions that aim to maintain vascular health through beneficial actions on cell populations with vasculogenic potential ("EPC"). The role of physical activity and dietary recommendations, which are considered essential elements of a healthy lifestyle, will be particularly emphasized. A thorough understanding of the physiology of endothelial benefits, derived from such interventions, may help to implement these measures on top of classical drug therapy, but also provides a solid basis for primary prevention. The effects of additional elements of a comprehensive lifestyle advice, such as smoking cessation, weight and stress reduction, also comprise a modulation of EPC function and circulating numbers and are therefore included in this review as well.

[Perspectives of regenerative mechanisms in cardiovascular disease spotlighting endothelial progenitor cells]

Cardiovascular diseases are the most common cause of death in the Western world. In general, the underlying disease is atherosclerosis, which is hallmarked by deterioration of the endothelial monolayer. Restoration of an intact endothelial monolayer for prevention and therapy of cardiovascular diseases is one key concept of regenerative medicine. This article offers a review of state-of-the-art regenerative mechanisms in cardiovascular disease spotlighting endothelial progenitor cells, and further features the perspectives of regenerative medicine in vascular biology.

Circulating CD34+/KDR+ endothelial progenitor cells are reduced in chronic heart failure patients as a function of Type D personality

The aim of the present study was to assess whether EPC (endothelial progenitor cell) number/function might be an explanatory factor for the observed relationship between Type D personality (a joint tendency towards negative affectivity and social inhibition) and poor cardiovascular prognosis. We also assessed whether the effect of a single exercise bout on EPC number/function was affected by Type D personality. A total of 35 sedentary men with CHF (chronic heart failure; left ventricular ejection fraction <or=45%) underwent CPET (cardiopulmonary exercise testing) and personality assessment with the 14-item Type D scale. CD34+/KDR (kinase insert domain-containing receptor)+ cells were quantified by flow cytometry before and immediately after CPET. Migration of early EPC towards VEGF (vascular endothelial growth factor) and SDF-1alpha (stromal-cell-derived factor-1alpha) was investigated. Type D (n=10) and non-Type D (n=25) patients were comparable with regards to demographics, disease severity and Framingham risk factor score. Circulating EPC numbers were reduced by 54% in Type D compared with non-Type D patients (0.084+/-0.055 and 0.183+/-0.029% of lymphocytes respectively; P=0.006). Exercise led to a 60% increase in EPC in Type D patients, whereas the EPC number remained unchanged in the non-Type D group (P=0.049). Baseline migratory capacity was related to disease severity, but was not different between Type D and non-Type D patients. Exercise induced a highly significant enhancement of migratory capacity in both groups. In conclusion, reduced EPC numbers might explain the impaired cardiovascular outcome in Type D patients. The larger increase in circulating EPCs observed in these patients suggests that acute exercise elicits a more pronounced stimulus for endothelial repair.