White blood cells in a healthy adolescent population according to social and health characteristics.

BACKGROUND: The immune system constitutes a sensory system both for heritable and non-heritable factors. Among the latter, social and environmental determinants of health may influence and shape the immune system in early life. To study the relationship between leukocytes and determinants of health in adolescence, we assessed total and differential white blood cells (WBC) according to social and environmental determinants of health in a healthy adolescent population. METHODS: As part of the population-based cohort Epidemiological Health Investigation of Teenagers in Porto (EPITeen), 1213 adolescents were evaluated at the age of 13. Total and differential WBC were evaluated through a venous blood sample using an automated blood counter (Sysmex®XE-5000, Hyogo, Japan). Sociodemographic, behavioral, and clinical data were collected through self-administered questionnaires. RESULTS: Participants with better socioeconomic conditions (enrolled at private schools or higher parental education) had significantly lower total WBC levels, and the latter showed a lower percentage of neutrophils and higher percentage of lymphocytes. Those who practiced sports had significantly lower total WBC levels and neutrophil percentage, as well as a significantly higher percentage of eosinophils and lymphocytes. Adolescents with chronic disease, chronic medication, or allergic diseases had a significantly higher percentage of eosinophils and a lower percentage of monocytes. With increasing body mass index and systemic inflammation, we found a significant increase in total WBC levels. CONCLUSION: WBC linked to different immune response patterns are associated with several social and environmental determinants of health in adolescence.

How the metabolic phenotype in adulthood is affected by long-lasting immunological trajectories since adolescence.

A close relationship between immune and metabolic systems has been perceived in the recent past. We aimed to assess whether the immunological trajectories of circulating white blood cells (WBC) started in adolescence, affects the metabolic phenotype in adulthood. We used data from 1183 participants of the population-based EPITeen cohort, evaluated at 13, 17, 21, 24 and 27 years of age. The Immunological trajectories from 13 to 27 years old were identified by mixed-effects models, being their association with metabolic features at 27 years old measured by logistic regression. The Higher Inflammatory Activation trajectory (HIA trajectory) had the highest percentage of individuals with metabolic syndrome, while Lowest Levels of WBC trajectory (LLWBC trajectory) showed the lowest percentage. Participants with HIA trajectory had significantly higher triglycerides, waist circumference, serum uric acid and BMI. After adjustment for sex and sports practice and hs-CRP, the odds of having one or more metabolic features in adulthood was significantly lower in LLWBC trajectory. Individuals with immunological trajectories of WBC linked with a pattern of higher immune activation showed a less favorable metabolic profile, while those with the lowest levels of WBC were less likely to have metabolic risk factors in adulthood.

Immunological Trajectories of White Blood Cells from Adolescence to Adulthood: Description and Determinants.

BACKGROUND: The immune system gradually matures early in life in the face of internal and external stimuli. Whether the immune responses are lasting and stable during the course of life is still unclear. METHODS: As part of the EPITeen cohort, 1183 adolescents were prospectively evaluated at the ages of 13, 17, 21, 24 and 27. Sociodemographic, behavioral and clinical data were collected by self- and face-to-face-administered questionnaires, along with a physical examination comprising anthropometric measurements and blood sample collections. Mixed-effects models were used to identify individual trajectories of white blood cells (WBC) and finite Gaussian mixture models were used to identify the clusters of individual trajectories. RESULTS: Participants were allocated into six clusters based on the individual trajectories of WBC distribution. Higher Inflammatory Activation Cluster (11.4%) had the highest total WBC count and neutrophils percentage, as well as the lowest percentage of lymphocytes. These participants had significantly higher odds of being overweight [OR = 2.44, 95%CI:1.51-3.92]. Lowest Levels of WBC Cluster (24.1%) had the lowest total WBC count, being characterized by a higher participation on sports [OR = 1.54, 95%CI:1.12-2.13]. Highest Proportion of Eosinophils Cluster (20.1%) had the highest eosinophils percentage and the highest likelihood of having been diagnosed with a chronic disease [OR = 2.11, 95%CI:1.43-3.13], namely "asthma or allergies" [OR = 14.0 (1.73, 112.2]. Lowest Proportion of Eosinophils Cluster (29.1%) had the lowest percentage of eosinophils and basophils, as well as the highest lymphocyte proportion. Participants in the Undefined Cluster (13.8%) showed the highest percentage of monocytes and basophils and were also characterized by significant lower odds of having parents with 7-9 years of schooling [OR = 0.56, (0.32, 0.99]. CONCLUSIONS: In this study we identified distinct immunological trajectories of WBC from adolescence to adulthood that were associated with social, clinical and behavioral determinants. These results suggest that these immunological trajectories are defined early in life, being dependent on the exposures.

The effect of impact exercise on bone mineral density: A longitudinal study on non-athlete adolescents.

PURPOSE: High impact exercise is known to induce osteogenic effects in the skeleton. However, less is known about the systemic effect of exercise practice in a potential adaptive mechanism of the skeletal accrual. This research aimed to assess the effect of impact exercise on bone mineral density (BMD) in the radius throughout adolescence. METHODS: This study evaluated 1137 adolescents, at 13 and 17 years old, as part of the population-based cohort EPITeen. BMD (g/cm2) was measured at the ultradistal and proximal radius of the non-dominant forearm by dual-energy X-ray absorptiometry (DXA) using a Lunar® Peripheral Instantaneous X-ray Image device. The practice of (extra-curricular) exercise was categorized as: no exercise, exercise with high impact and exercise with low impact. Regression coefficients (ß) and respective 95% confidence intervals (CI95%) were used to estimate the association between exercise practice categories at 13 years old and BMD at 13 and 17 years old and BMD gain between evaluations. RESULTS: In boys, at 13 years, BMD was similar between the ones not practicing exercise and those practicing exercise with low impact, and the gain of BMD was also similar in both groups. Still in boys, at 13 years, those who practiced exercise with high impact presented higher mean (standard-deviation) of BMD, comparing to the other two groups (no exercise and low impact exercise), and also significantly increased the BMD gain between 13 and 17 years (ß = 0.013; CI95%0.003;0.023). In girls, no statistically significant differences on BMD were found between the categories of exercise at 13 years and BMD at 17 years of age. CONCLUSION: This research shows that the practice of high impact exercise could help to increase BMD more than low impact exercise even in a nonweight-bearing bone during adolescence.

Metabolically healthy overweight in young adulthood: is it a matter of duration and degree of overweight?

BACKGROUND AND AIM: Given the controversy regarding metabolically healthy obesity, we studied the association between duration and degree of body mass index (BMI) from adolescence to early adulthood and metabolic status of both overweight/obese and under/normal weight subjects. METHODS AND RESULTS: Participants of the EPITeen cohort were evaluated at 13, 17, 21 and 24 years (n = 1040). Duration and degree of BMI in the 11-year period was summarized through the area under the curve of BMI (BMIAUC). Metabolic health at 24 y was defined as optimal levels of lipids, blood pressure and glucose. The association between BMIAUC per year and metabolic health was estimated through binary logistic regression models, adjusted for confounders and stratified by BMI. The proportion of metabolically healthy overweight/obesity at 24 y was 13.4%. After adjustment for sociodemographic and behavioural factors, the increase of one kg/m2 in BMI on average per year during the period between 13 and 24 y was associated with 14% lower odds of being metabolically healthy among under/normal weight participants (OR = 0.86, 95% CI 0.78-0.94); and 8% lower odds of metabolic health among obese/overweight participants (OR = 0.92, 95% CI 0.85-1.00). After additional adjustment for waist circumference, the association was attenuated, especially in the obese/overweight group (OR = 1.03, 95% CI 0.93-1.14). About 20% of the metabolically healthy obese/overweight at 13 y transitioned to metabolically unhealthy obesity/overweight at 24 y. CONCLUSION: The results support the hypothesis that the healthy obesity phenotype could be explained by a lower exposure to adiposity, either by shorter time or lower quantity, and a more favourable body fat distribution.

Association of Serum 25-Hydroxyvitamin D Concentration with Pulmonary Function in Young Adults.

The role of vitamin D on pulmonary function is unclear and is mostly studied in patients, smokers and elderly people. The aim of this paper was to evaluate the association between serum 25-hydroxyvitamin D [25(OH)D] concentration and pulmonary function in young adults. Cross-sectional analysis of 499 individuals that were evaluated at 21 years of age as part of the population-based cohort Epidemiological Health Investigation of Teenagers in Porto (EPITeen). Serum 25(OH)D was categorized according to the Institute of Medicine. Pulmonary function was evaluated using spirometry. Linear regression models were used to estimate the regression coefficients (ß) and its 95% confidence intervals (95% CI), and were adjusted for confounders. Education, smoking, body mass index, and season of evaluation were determinants of serum 25(OH)D concentration. Prevalence of serum 25(OH)D concentration <50 nmol/L was 48.9%. A decrease in all pulmonary function parameters, with the decrease of serum 25(OH)D, was observed. The higher effect was found for peak expiratory flow (PEF). Having as reference participants with serum 25(OH)D concentration ≥50 nmol/L, PEF was significantly lower for those with a concentration of 30 to <50 nmol/L (ß= -0.576; 95% CI: -0.943, -0.210), and for those with a concentration of <30 nmol/L (ß= -0.650; 95% CI: -1.155, -0.146). Although only PEF attained statistical significance, the consistent results with the other parameters support the role of serum 25(OH)D to promote better pulmonary function in young adults.