The endocrinology of exercise

Nutrition, obesity, and dental development in young adolescents in Chicago

OBJECTIVES

Childhood obesity is a systemic disease with multiple downstream consequences, including shifts in timing of growth and development. It has been documented that children with high body mass index (BMI) show accelerated timing of dental development, but the mechanism for this acceleration is unknown. Prior work has suggested that inflammation and/or nutrition may play a role. We investigate the potential association between diet (caloric intake, macronutrients), obesity, and accelerated dental development.

METHODS

Children and adolescents (age 10-15; n = 112) were recruited from dental clinics at the University of Illinois Chicago. We collected subjects' height, weight, panoramic radiographic records, and each subject filled out a Block Food Frequency Questionnaire.

RESULTS

The only macronutrient level associated with BMI was a negative correlation to Total Fat consumption (p = .01), though this relationship was not significant in the path analysis (p > .05). Regression analyses indicated that BMI (p = .003) and total caloric intake (controlling for BMI; rho = 0.19; p = .04) were both significantly correlated with timing of dental development. However, when a path analysis was conducted, it was revealed that only BMI was statistically significant (p = .008).

CONCLUSIONS

Body mass index percentile, regardless of caloric intake, is positively associated with accelerated dental development. While it is possible that excess caloric intake itself plays a minor role in timing of dental development, we do not see unambiguous evidence for this in our sample. We posit that another mechanism, such as inflammation, may be the link between obesity status and dental development.

Physical Activity and Insulin Resistance in 6,500 NHANES Adults: The Role of Abdominal Obesity

This cross-sectional investigation studied differences in insulin resistance across levels of physical activity in 6,500 US adults who were randomly selected as part of the National Health and Nutrition Examination Survey (NHANES). Another important objective was to determine the influence of abdominal obesity on the physical activity and insulin resistance relationship. MET-minutes were utilized to quantify total activity based on participation in 48 different physical activities. Two strategies were employed to categorize levels of physical activity: one was based on relative MET-minutes (quartiles), and the other approach was based on the US physical activity guidelines. Insulin resistance was indexed using the homeostatic model assessment (HOMA). Abdominal obesity was indexed using waist circumference. Effect modification was tested by dividing waist circumferences into sex-specific quartiles and then evaluating the relationship between physical activity and HOMA-IR within each quartile separately. Results showed that relative physical activity level was associated with HOMA-IR after controlling for demographic and demographic and lifestyle covariates (F = 11.5, P < 0.0001 and F = 6.0, P=0.0012, respectively). Adjusting for demographic and demographic and lifestyle covariates also resulted in significant relationships between guideline-based activity and HOMA-IR (F = 8.0, P < 0.0001 and F = 4.9, P=0.0017, respectively). However, statistically controlling for differences in waist circumference with the other covariates nullified the relationship between total physical activity and HOMA-IR. Effect modification testing showed that when the sample was delimited to adults with abdominal obesity (Quartile 4), relative (F = 5.6, P=0.0019) and guideline-based physical activity (F = 3.7, P=0.0098) and HOMA-IR were significantly associated. Physical activity and HOMA-IR were not related within the other three quartiles. In conclusion, it appears that differences in physical activity may play a meaningful role in insulin resistance in those with abdominal obesity, but total activity does not seem to account for differences in insulin resistance among US adults with smaller waists.

Inflammation and Immune Regulation as Potential Drug Targets in Antidepressant Treatment

Growing evidence supports a mutual relationship between inflammation and major depression. A variety of mechanisms are outlined, indicating how inflammation may be involved in the pathogenesis, course and treatment of major depression. In particular, this review addresses 1) inflammatory cytokines as markers of depression and potential predictors of treatment response, 2) findings that cytokines interact with antidepressants and non-pharmacological antidepressive therapies, such as electroconvulsive therapy, deep brain stimulation and physical activity, 3) the influence of cytokines on the cytochrome (CYP) p450-system and drug efflux transporters, and 4) how cascades of inflammation might serve as antidepressant drug targets. A number of clinical trials have focused on agents with immunmodulatory properties in the treatment of depression, of which this review covers nonsteroidal anti-inflammatory drugs (NSAIDs), cytokine inhibitors, ketamine, polyunsaturated fatty acids, statins and curcumin. A perspective is also provided on possible future immune targets for antidepressant therapy, such as toll-like receptor-inhibitors, glycogen synthase kinase-3 inhibitors, oleanolic acid analogs and minocycline. Concluding from the available data, markers of inflammation may become relevant factors for more personalised planning and prediction of response of antidepressant treatment strategies. Agents with anti-inflammatory properties have the potential to serve as clinically relevant antidepressants. Further studies are required to better define and identify subgroups of patients responsive to inflammatory agents as well as to define optimal time points for treatment onset and duration.

Vitamin D supplementation affects the IGF system in men after acute exercise

OBJECTIVE

Contradictory data between the Insulin-Like Growth Factor System (IGF) system and exercise may be due to alteration in IGF binding proteins. Vitamin D (D) deficiency has been related to muscle weakness and Insulin Like Growth Factor Binding Protein 3 (IGFBP3). A Vit. D and acute exercise merge is proposed to modify the IGF system.

DESIGN

D insufficient and deficient men (39.0±8.6yo with serum D (25OH D) 20.0±7.7ng/mL) did 1h of stretching (ST), aerobic (AB), and resistance (RT) exercises, before and after 28d of 4000IU/d Vit. D3 (D, n=6) or Placebo (P, n=7). ST, a time/attention control visit, interchanged unreceptive movements. AB was moderate intensity treadmill walking. RT rotated moderate strength 50% 1-RM repetitions (15, 10) of squat, bench press, leg press, and lat pull down. Serum Total IGF1 (TIGF1), Insulin Like Growth Factor Binding Protein 1 (IGFBP1), and IGFBP3 were measured before (T1, fasting), immediately after (T2), and 2h post (T3) exercise.

RESULTS

After ST, IGFBP3 was greater in the D group at T2 (2948, 2130ng/mL; p<0.03) and T3 (3087, 2212; p<0.02). During RT, TIGF1 decreased in the Placebo (P) group from T1 to T3 (151.4, 107.3ng/mL; p<0.05), while IGFBP1 increased in the D group from T1 to T3 (26.5, 96.2ng/mL; p<0.05). RT IGFBP3 was greater at T1, T2, and T3 in the D group (2932.5, 2110.7; p<0.03), (3163.9, 2392.5; p<0.04), and (3355.3, 2353.1; p<0.01). In AB, IGFBP3 was greater in the D group at T2 (3128.6, 2226.3.0; p<0.04) and T3 (2949.7, 2135.1; p<0.05).

CONCLUSION

D supplementation amplified IGFBP3 after low or moderate activity which may increase the delivery of IGF1 to tissues. Resistance exercise with D not only increased IGFBP3 and IGFBP1 levels but also conserved TIGF1 levels, possibly shifting the IGF system for enriched muscle well-being.

Physical activity and exercise attenuate neuroinflammation in neurological diseases

Major depressive disorder (MDD), schizophrenia (SCH), Alzheimer's disease (AD), and Parkinson's disease (PD) are devastating neurological disorders, which increasingly contribute to global morbidity and mortality. Although the pathogenic mechanisms of these conditions are quite diverse, chronic neuroinflammation is one underlying feature shared by all these diseases. Even though the specific root causes of these diseases remain to be identified, evidence indicates that the observed neuroinflammation is initiated by unique pathological features associated with each specific disease. If the initial acute inflammation is not resolved, a chronic neuroinflammatory state develops and ultimately contributes to disease progression. Chronic neuroinflammation is characterized by adverse and non-specific activation of glial cells, which can lead to collateral damage of nearby neurons and other glia. This misdirected neuroinflammatory response is hypothesized to contribute to neuropathology in MDD, SCH, AD, and PD. Physical activity (PA), which is critical for maintenance of whole body and brain health, may also beneficially modify neuroimmune responses. Since PA has neuroimmune-modifying properties, and the common underlying feature of MDD, SCH, AD, and PD is chronic neuroinflammation, we hypothesize that PA could minimize brain diseases by modifying glia-mediated neuroinflammation. This review highlights current evidence supporting the disease-altering potential of PA and exercise through modifications of neuroimmune responses, specifically in MDD, SCH, AD and PD.

Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE)

An increasing recognition has emerged of the complexities of the global health agenda—specifically, the collision of infections and noncommunicable diseases and the dual burden of over- and undernutrition. Of particular practical concern are both 1) the need for a better understanding of the bidirectional relations between nutritional status and the development and function of the immune and inflammatory response and 2) the specific impact of the inflammatory response on the selection, use, and interpretation of nutrient biomarkers. The goal of the Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE) is to provide guidance for those users represented by the global food and nutrition enterprise. These include researchers (bench and clinical), clinicians providing care/treatment, those developing and evaluating programs/interventions at scale, and those responsible for generating evidence-based policy. The INSPIRE process included convening 5 thematic working groups (WGs) charged with developing summary reports around the following issues: 1) basic overview of the interactions between nutrition, immune function, and the inflammatory response; 2) examination of the evidence regarding the impact of nutrition on immune function and inflammation; 3) evaluation of the impact of inflammation and clinical conditions (acute and chronic) on nutrition; 4) examination of existing and potential new approaches to account for the impact of inflammation on biomarker interpretation and use; and 5) the presentation of new approaches to the study of these relations. Each WG was tasked with synthesizing a summary of the evidence for each of these topics and delineating the remaining gaps in our knowledge. This review consists of a summary of the INSPIRE workshop and the WG deliberations.

Inflammatory cytokines in general and central obesity and modulating effects of physical activity

Context

Chronic systemic inflammation in obesity originates from local immune responses in visceral adipose tissue. However, assessment of a broad range of inflammation-mediating cytokines and their relationship to physical activity and adipometrics has scarcely been reported to date.

Objective

To characterize the profile of a broad range of pro- and anti-inflammatory cytokines and the impact of physical activity and energy expenditure in individuals with general obesity, central obesity, and non-obese subjects.

Design, Setting, and Participants

A cross-sectional study comprising 117 obese patients (body mass index (BMI) ≥ 30) and 83 non-obese community-based volunteers.

Main Outcomes Measures

Serum levels of interleukin (IL)-2, IL-4, IL-5, IL-10, IL-12, IL-13, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (IFN)-γ and tumor necrosis factor (TNF)-α were measured. Physical activity and energy expenditure (MET) were assessed with actigraphy. Adipometrics comprised BMI, weight, abdominal-, waist- and hip-circumference, waist to hip ratio (WHR), and waist-to-height-ratio (WHtR).

Results

General obesity was associated with significantly elevated levels of IL-5, IL-10, IL-12, IL-13, IFN-γ and TNF-α, central obesity with significantly elevated IL-5, IL-10, IL-12, IL-13 and IFN-γ-levels. In participants with general obesity, levels of IL-4, IL-10 and IL-13 were significantly elevated in participants with low physical activity, even when controlled for BMI which was negatively associated with physical acitivity. Cytokines significantly correlated with adipometrics, particularly in obese participants.

Conclusions

Results confirm up-regulation of certain pro- and anti-inflammatory cytokines in obesity. In obese subjects, physical activity may lower levels and thus reduce pro-inflammatory effects of cytokines that may link obesity, insulin resistance and diabetes.

The hypothalamic-pituitary-adrenal-leptin axis and metabolic health: a systems approach to resilience, robustness and control

Glucocorticoids contribute to obesity and metabolic syndrome; however, the mechanisms are unclear, and prognostic measures are unavailable. A systems level understanding of the hypothalamic-pituitary-adrenal (HPA)-leptin axis may reveal novel insights. Eighteen obese premenopausal women provided blood samples every 10 min over 24 h, which were assayed for cortisol, adrenocorticotropin releasing hormone (ACTH) and leptin. A published personalized HPA systems model was extended to incorporate leptin, yielding three parameters: (i) cortisol inhibitory feedback signalling, (ii) ACTH-adrenal signalling, and (iii) leptin-cortisol antagonism. We investigated associations between these parameters and metabolic risk profiles: fat and lean body mass (LBM; using dual-energy X-ray absorptiometry), and insulin resistance. Decreased cortisol inhibitory feedback signalling was significantly associated with greater fat (kg; p = 0.01) and insulin resistance (p = 0.03) but not LBM. Leptin significantly antagonized cortisol dynamics in eight women, who exhibited significantly lower 24 h mean leptin levels, LBM and higher ACTH-adrenal signalling nocturnally (all p < 0.05), compared with women without antagonism. Traditional neuroendocrine measures did not predict metabolic health, whereas a dynamic systems approach revealed that lower central inhibitory cortisol feedback signalling was significantly associated with greater metabolic risk. While exploratory, leptin-cortisol antagonism may reflect a 'neuroendocrine starvation' response.

Taming HIV-related inflammation with physical activity: a matter of timing

Many sets of data indicate that HIV-infected individuals maintain a low level of chronic immune activation and inflammation even in the presence of effective antiretroviral therapy (ART). This residual immune activation seems to be associated with accelerated aging and an increased incidence of non-AIDS-defining illnesses. Several published studies suggest that physical activity is a beneficial nonpharmacological intervention to reduce chronic inflammation. However, currently available data on the potential benefits of regular physical exercises for HIV-infected individuals are limited. Nonetheless, increasing evidence suggests that the introduction of regular physical exercise in the clinical management of HIV-infected individuals may have a significant positive impact in reducing some of the long-term complications of both infection and ART. Based on a comprehensive review of the existing data, we propose that regular physical exercise should be further studied as a potential antiinflammatory, nonpharmacological approach to be used to treat HIV residual disease and non-AIDS-defining illnesses in ART-treated HIV-infected individuals.

Cytokine levels in depressed and non-depressed subjects, and masking effects of obesity

In major depressive disorder, changes in cytokine levels have been reported to play a role in pathogenesis. Therefore, we sought to investigate a broad range of cytokines in depression. We compared serum levels of interleukin (IL)-2, IL-4, IL-5, IL-10, IL-12, IL-13, granulocyte macrophage colony-stimulating factor (GM-CSF), interferon (INF-γ) and tumor necrosis factor (TNF)-α in 64 subjects with current depression and 206 non-depressed subjects. Depressed patients had higher levels of IL-2, IL-5, IL-12, IL-13, GM-CSF, INF-γ and TNF-α, compared to non-depressed subjects. Splitting groups into non-obese (BMI < 30) and obese (BMI ≥ 30), the non-obese depressed patients (n = 40) showed elevated IL-5, IL-12, IL-13, GM-CSF, INF-γ and TNF-α levels compared to non-obese and non-depressed subjects (n = 85). The obese and depressed patients (n = 24) showed elevated levels of IL-5, IL-12 and INF-γ compared to obese but not depressed subjects (n = 121). Levels of several cytokines were found to be associated with physical activity, employment status and presence of daily naps. The results support over-expression of pro-inflammatory cytokines in depression and extend the range of cytokines potentially associated with depression to include GM-CSF, IL-5 and IL-13. Changes in these cytokines may contribute to co-morbidity between depression and allergic and asthmatic diseases. The results also suggest inflammatory processes associated with obesity, and support an interaction between cytokine serum concentrations and behavioral aspects of both obesity and depression.

Adipose tissue inflammation and metabolic dysfunction: role of exercise

Our current environment has led to a vicious cycle of physical inactivity, obesity, and chronic inflammation, creating the "perfect storm" for metabolic diseases. White adipose tissue (WAT) is the major source of obesity/ inactivity-related inflammation; in turn, inflammation leads to insulin resistance and metabolic dysfunction. Inactivity, even in the absence of weight gain, disrupts WAT metabolism, while exercise mitigates WAT inflammation. The antiinflammatory mechanism(s) of exercise require additional study. Two current hypotheses include: (1) exercise-mediated antiinflammatory cytokine secretion, and (2) exercise-mediated improvements in adipocyte oxidative capacity.