Circulating progenitor cells are positively associated with cognitive function among overweight/obese children

Increased innate immune responses in adolescents with obesity and its relation to subclinical cardiovascular measures: An exploratory study

Cardiometabolic risk accrues across the life course and childhood and adolescence are key periods for effective prevention. Obesity is associated with inflammation in adults, but pediatric data are scarce. In a cross-sectional and longitudinal study, we investigated immune cell composition and activation in 31 adolescents with obesity (41.9% male, BMIz>2.5, 14.4 years) and 22 controls with healthy weight (45.1% male, -1.5 Collapse

Key Words

• Disease
• Health sciences
• Immunology
• Pathophysiology
• Risk factor

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Affiliation(s)

Siroon Bekkering Department of Internal Medicine, Radboud University Medical Centre, Nijmegen 6525 GA, the Netherlands Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC 3052, Australia
Christoph Saner Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC 3052, Australia Division of Pediatric Endocrinology, Diabetology and Metabolism, Department of Pediatrics, University Children`s Hospital Bern, Inselspital, Bern 3010, Switzerland Department of Biomedical Research, University of Bern, 3010 Bern, Switzerland
Boris Novakovic Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC 3052, Australia Department of Paediatrics, The University of Melbourne, Parkville, VIC 3052, Australia
Toby Mansell Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC 3052, Australia Department of Paediatrics, The University of Melbourne, Parkville, VIC 3052, Australia
Danielle K. Longmore Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC 3052, Australia Department of Endocrinology, The Royal Children`s Hospital, Parkville, VIC 3052, Australia
Zoe McCallum Department of Paediatrics, The University of Melbourne, Parkville, VIC 3052, Australia Department of Neurodevelopment and Disability, Royal Children’s Hospital, Parkville, VIC 3052, Australia
Anne-Louise Ponsonby Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC 3052, Australia Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC 3052, Australia
Markus Juonala Department of Medicine, University of Turku, 20500 Turku, Finland Division of Medicine, Turku University Hospital, 20500 Turku, Finland
Mihai G. Netea Department of Internal Medicine, Radboud University Medical Centre, Nijmegen 6525 GA, the Netherlands Department of Immunology and Metabolism, Life and Medical Sciences Institute, University of Bonn, 53115 Bonn, Germany
Matthew A. Sabin Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC 3052, Australia Department of Endocrinology, The Royal Children`s Hospital, Parkville, VIC 3052, Australia Department of Paediatrics, The University of Melbourne, Parkville, VIC 3052, Australia
Richard Saffery Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC 3052, Australia Department of Paediatrics, The University of Melbourne, Parkville, VIC 3052, Australia
Niels P. Riksen Department of Internal Medicine, Radboud University Medical Centre, Nijmegen 6525 GA, the Netherlands
David P. Burgner Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, VIC 3052, Australia Department of Paediatrics, The University of Melbourne, Parkville, VIC 3052, Australia Department of Pediatrics, Monash University, Clayton, VIC 3168, Australia

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How Does Lifestyle Affect Hematopoiesis and the Bone Marrow Microenvironment?

Lifestyle factors are modifiable behavioral factors that have a significant impact on health and longevity. Diet-induced obesity and physical activity/exercise are two prevalent lifestyle factors that have strong relationships to overall health. The mechanisms linking obesity to negative health outcomes and the mechanisms linking increased participation in physical activity/exercise to positive health outcomes are beginning to be elucidated. Chronic inflammation, due in part to overproduction of myeloid cells from hematopoietic stem cells (HSCs) in the bone marrow, is an established mechanism responsible for the negative health effects of obesity. Recent work has shown that exercise training can reverse the aberrant myelopoiesis present in obesity in part by restoring the bone marrow microenvironment. Specifically, exercise training reduces marrow adipose tissue, increases HSC retention factor expression, and reduces pro-inflammatory cytokine levels in the bone marrow. Other, novel mechanistic factors responsible for these exercise-induced effects, including intercellular communication using extracellular vesicles (EVs), is beginning to be explored. This review will summarize the recent literature describing the effects of exercise on hematopoiesis in individuals with obesity and introduce the potential contribution of EVs to this process.

Circulating Progenitor Cells and Cognitive Impairment in Men and Women with Coronary Artery Disease

BACKGROUND

Circulating progenitor cells (CPC) have been associated with memory function and cognitive impairment in healthy adults. However, it is unclear whether such associations also exist in patients with coronary artery disease (CAD).

OBJECTIVE

To assess the association between CPCs and memory performance among individuals with CAD.

METHODS

We assessed cognitive function in 509 patients with CAD using the verbal and visual Memory subtests of the Wechsler memory scale-IV and the Trail Making Test parts A and B. CPCs were enumerated with flow cytometry as CD45med/CD34+ blood mononuclear cells, those co-expressing other epitopes representing populations enriched for hematopoietic and endothelial progenitors.

RESULTS

After adjusting for demographic and cardiovascular risk factors, lower number of endothelial progenitor cell counts were independently associated with lower visual and verbal memory scores (p for all < 0.05). There was a significant interaction in the magnitude of this association with race (p < 0.01), such that the association of verbal memory scores with endothelial progenitor subsets was present in Black but not in non-Black participants. No associations were present with the hematopoietic progenitor-enriched cells or with the Trail Making Tests.

CONCLUSION

Lower numbers of circulating endothelial progenitor cells are associated with cognitive impairment in patients with CAD, suggesting a protective effect of repair/regeneration processes in the maintenance of cognitive status. Impairment of verbal memory function was more strongly associated with lower CPC counts in Black compared to non-Black participants with CAD. Whether strategies designed to improve regenerative capacity will improve cognition needs further study.

Trained Immunity: Linking Obesity and Cardiovascular Disease across the Life-Course?

Obesity, a chronic inflammatory disease, is the most prevalent modifiable risk factor for cardiovascular disease. The mechanisms underlying inflammation in obesity are incompletely understood. Recent developments have challenged the dogma of immunological memory occurring exclusively in the adaptive immune system and show that the innate immune system has potential to be reprogrammed. This innate immune memory (trained immunity) is characterized by epigenetic and metabolic reprogramming of myeloid cells following endogenous or exogenous stimulation, resulting in enhanced inflammation to subsequent stimuli. Trained immunity phenotypes have now been reported for other immune and non-immune cells. Here, we provide a novel perspective on the putative role of trained immunity in mediating the adverse cardiovascular effects of obesity and highlight potential translational pathways.

A Carbohydrate Beverage Reduces Monocytes Expressing TLR4 in Children with Overweight or Obesity

BACKGROUND

Childhood obesity is increasing, with about one-third of children overweight or obese. Obesity is characterized by a state of chronic low-grade inflammation that is related to cardiometabolic comorbidities. Inflammatory monocytes, which are classified into 3 different groups-classical, intermediate, and nonclassical monocytes, with Toll-like receptor 4 (TLR4+) expression indicating a proinflammatory state-underlie several obesity-associated morbidities.

OBJECTIVES

This study aimed to assess the responses of monocyte populations to beverages of differing macronutrient composition in children with healthy weight (HW) or overweight/obesity (OW/OB).

METHODS

Ten HW children (5th to 84.9th percentile; mean age 12.29 ± 2.5 y) and 7 children with OW/OB (85th to 99.99th percentile; mean age 11.96 ± 3.8 y) completed the study. Adiposity was determined via DXA. Using a double-blinded, randomized, crossover design, participants consumed either a high-carbohydrate (CHO; 210 kcal; 0 g fat/56 g carbohydrates/0 g protein) or a whole-egg-based high-protein/fat (EGG; 210 kcal; 15 g fat/0 g carbohydrates/18 g protein) beverage. Venous blood was collected at baseline and 2 h postprandially for evaluation of metabolic and inflammatory responses. Repeated measures ANOVA and Pearson correlations were conducted.

RESULTS

Consuming the CHO beverage significantly reduced the primary outcome: TLR4+ expression on classical monocytes in children with OW/OB only (25.60% decrease from baseline in OW/OB compared with 1.61% increase in HW). Children with OW/OB had significantly less percentages of TLR4+ nonclassical monocytes than HW (47.66% lower after CHO). Insulin and glucose (secondary outcomes), were significantly higher after the CHO condition compared with baseline (230.61% and 9.93% increase, respectively). Changes in glucose were significantly and negatively related to changes in monocyte populations in the CHO condition.

CONCLUSIONS

These data suggest that high-carbohydrate beverages alter monocyte populations in the blood in children with OW/OB, which is related to glucose metabolism. These findings have implications for nutritional recommendations in children with overweight/obesity. National Clinical Trial registry trial number: NCT03597542.

Effects of Obesity and Exercise on Bone Marrow Progenitor Cells after Radiation

INTRODUCTION

The late effects of radiation therapy can have significant consequences for the health and quality of life of long-term cancer survivors. Radiation induces persistent alterations in hematopoietic stem and progenitor cells (HSPC) and the bone marrow environment; however, how relevant host factors such as obesity and exercise differentially regulate HSPC content and the bone marrow environment after radiation exposure remains unknown. The purpose of this investigation was to evaluate how the combination of obesity and exercise training modulates HSPC and their niche after sublethal radiation exposure in mice.

METHODS

Mice fed either a control or a high-fat diet to induce obesity remained sedentary or underwent a progressive treadmill exercise program. At 13 wk of age, mice were irradiated (3 Gy) and continued their specific diets and exercise program for four more weeks.

RESULTS

Exercise-trained mice had significantly higher quantities of several HSPC subpopulations and bone marrow stromal cell populations, whereas HSPC subpopulations were significantly lower in obese mice after radiation. Reactive oxygen species content was significantly decreased in HSPC with exercise training. Proteomics analysis of bone marrow supernatant revealed clustering of biologically relevant changes in exercise-trained mice. Functional evaluation of bone marrow supernatant revealed a significant increase in leukemia blast viability in obese mice but not in the exercise-trained mice (P < 0.05).

CONCLUSION

Together, these data suggest that exercise training partially restores the negative effects of obesity on HSPC and their niche after radiation exposure. As such, exercise training should be considered to mitigate the late effects of radiation therapy on the hematopoietic system for cancer survivors with or without obesity who have undergone radiation therapy.

Executive and Reward-Related Function in Pediatric Obesity: A Meta-Analysis

OBJECTIVE

This study examined the effect of pediatric obesity on executive function and reward-related decision-making, cognitive processes that are relevant to obesogenic behaviors, and evaluated their association with sample (e.g., age, gender, intelligence, and socioeconomic status, SES) and study/task (e.g., categorical/continuous variable, food stimuli) characteristics.

METHODS

A random-effects meta-analysis was conducted using Hedge's g effect sizes of published studies from 1960 to 2016, limited to children younger than the age of 21 years without medical comorbidities. Analysis included estimation of heterogeneity (τ²), publication bias (funnel-plot symmetry and fail-safe N), and sensitivity analyses for sample and study/task characteristics.

RESULTS

Across 68 studies with 70 samples, obesity was associated with worse functioning overall (-0.24; 95CI: -0.30 to -0.19; p < 0.001) and for each component process (attention, switching, inhibition, interference, working memory, reward, delay of gratification: -0.19 to -0.38; p's < 0.017), except trait impulsivity (-0.06; 95CI: -0.18 to 0.07). Deficits increased with age and female composition of the sample for inhibition (p = 0.002). No other characteristics moderated effect of obesity.

CONCLUSIONS

Small-to-moderate negative associations with obesity were observed for executive and reward-related performance, but not on reported impulsivity in studies with children younger than the age of 21 years. These results were not moderated by IQ, SES, and study/task characteristics. Age and gender moderated association with inhibition, with a larger obesity-related deficit in older and predominantly female samples. These results suggest cognitive and demographic intervention targets for prevention and mitigation of obesogenic behavior.

Effects of endurance exercise training on inflammatory circulating progenitor cell content in lean and obese adults

KEY POINTS

Chronic inflammation underlies many of the health decrements associated with obesity. Circulating progenitor cells can sense and respond to inflammatory stimuli, increasing the local inflammatory response within tissues. Here we show that 6 weeks of endurance exercise training significantly decreases inflammatory circulating progenitor cells in obese adults. These findings provide novel cellular mechanisms for the beneficial effects of exercise in obese adults.

ABSTRACT

Circulating progenitor cells (CPCs) and subpopulations are normally found in the bone marrow, but can migrate to peripheral tissues to participate in local inflammation and/or remodelling. The purpose of this study was to compare the CPC response, particularly the inflammatory-primed haematopoietic stem and progenitor (HSPC) subpopulation, to a 6 week endurance exercise training (EET) intervention between lean and obese adults. Seventeen healthy weight (age: 23.9 ± 5.4 years, body mass index (BMI): 22.0 ± 2.6 kg m^-2 ) and 10 obese (age: 29.0 ± 8.0 years, BMI: 33.1 ± 6.0 kg m^-2 ) previously sedentary adults participated in an EET. Blood was collected before and after EET for quantification of CPCs and subpopulations via flow cytometry, colony forming unit assays and plasma concentrations of C-X-C motif chemokine 12 (CXCL12), granulocyte-colony stimulating factor (G-CSF), and chemokine (C-C motif) ligand 2 (CCL2). Exercise training reduced the number of circulating HSPCs and adipose tissue-derived mesenchymal stem cells (AT-MSCs). EET increased the colony forming potential of granulocytes and macrophages irrespective of BMI. EET reduced the number of HSPCs expressing the chemokine receptor CCR2 and the pro-inflammatory marker TLR4. EET-induced changes in adipose tissue-derived MSCs and bone marrow-derived MSCs were negatively related to changes in absolute fitness. Our results indicate that EET, regardless of BMI status, decreases CPCs and subpopulations, particularly those primed for contribution to tissue inflammation.

Kinetics of circulating progenitor cell mobilization during submaximal exercise

Circulating progenitor cells (CPCs) are a heterogeneous population of stem/progenitor cells in peripheral blood that includes hematopoietic stem and progenitor cells (HSPCs and HSCs), endothelial progenitor cells (EPCs), and mesenchymal stem cells (MSCs) that are involved in tissue repair and adaptation. CPC mobilization during exercise remains uncharacterized in young adults. The purpose of this study was to investigate the kinetics of CPC mobilization during and after submaximal treadmill running and their relationship to mobilization factors. Seven men [age = 25.3 ± 2.4 yr, body mass index = 23.5 ± 1.0 kg/m2, peak O2uptake (V̇o2peak) = 60.9 ± 2.74 ml·kg−1·min−1] ran on a treadmill for 60 min at 70% V̇o2peak. Blood sampling occurred before (Pre), during [20 min (20e), 40 min (40e), 60 min (60e)], and after exercise [15 min (15p), 60 min (60p), 120 min (120p)] for quantification of CPCs (CD34+), HSPCs (CD34+/CD45low), HSCs (CD34+/CD45low/CD38−), CD34+MSCs (CD45−/CD34+/CD31−/CD105+), CD34−MSCs (CD45−/CD34−/CD31−/CD105+), and EPCs (CD45−/CD34+/CD31+) via flow cytometry. CPC concentration increased compared with Pre at 20e and 40e (2.7- and 2.4-fold, respectively, P < 0.05). HSPCs and HSCs increased at 20e compared with 60p (2.7- and 2.8-fold, respectively, P < 0.05), whereas EPCs and both MSC populations did not change. CXC chemokine ligand (CXCL) 12 (1.5-fold; P < 0.05) and stem cell factor (1.3-fold; P < 0.05) were increased at 40e and remained elevated postexercise. The peak increase in CPCs was positively correlated to concentration of endothelial cells during exercise with no relationship to CXCL12 and SCF. Our data show the kinetics of progenitor cell mobilization during exercise that could provide insight into cellular mediators of exercise-induced adaptations, and have implication for the use of exercise as an adjuvant therapy for CPC collection in hematopoietic stem cell transplant.

NEW & NOTEWORTHY Using a comprehensive evaluation of circulating progenitor cells (CPCs), we show that CPC mobilization during exercise is related to tissue damage, and not plasma concentrations of CXC chemokine ligand 12 and stem cell factor. These data have implications for the use of exercise interventions as adjuvant therapy for CPC mobilization in the context of hematopoietic stem cell transplant and also support the role of mobilized progenitor cells as cellular mediators of systemic adaptations to exercise.

Cognitive Function and the Microbiome

There is increasing evidence that the composition of the resident bacteria within the gastrointestinal tract can influence the brain and behavior, particularly with respect to cognitive function. Cognitive function encompasses the life-long process of learning, both long- and short-term processes. Cognition was originally thought to be exclusively regulated by the central nervous system, with long-term potentiation and neurogenesis contributing to the creation and storage of memories, but now other systems, including, for example, the immune system and the intestinal microbiome may also be involved. Cognitive impairment has been identified in numerous disease states, both gastrointestinal and extraintestinal in nature, many of which have also been characterized as having a role for dysbiosis in disease pathogenesis. This includes, but is not limited to, inflammatory bowel diseases, irritable bowel syndrome, type 1 diabetes, obesity, major depressive disorder, and autism spectrum disorder. The role of cognition and the microbiome will be discussed in this chapter for all these diseases, as well as evidence for a role in maintaining overall human health and well being. Finally, evidence for a role for probiotics in beneficially modulating the microbiota and leading to improved cognition will be discussed.