Sex dimorphisms in inflammatory markers and adiposity in African-American youth

The CCR2+ Monocyte Subsets Increase in Obese Boys but Not Girls with Abnormally High Carotid Intima-Media Thickness: A Pilot Study

The differential contribution of monocyte subsets expressing the C-C chemokine receptor 2 (CCR2) to subclinical atherosclerosis in girls and boys is unclear. In this pilot study, we compared classical, intermediate, and nonclassical monocyte subsets expressing CCR2 in 33 obese children of both sexes aged 8 to 16 divided by carotid intima-media thickness (IMT), considering values above the 75th percentile (p75) as abnormally high IMT. Obesity was defined as body mass index above the 95th percentile according to age and sex. Flow cytometry analyses revealed that boys but not girls with IMT ≥ p75 displayed increased CCR2+ cell percentage and CCR2 expression in the three monocyte subsets, compared to boys with IMT < p75. The CCR2+ cell percentage and CCR2 expression in the three monocyte subsets significantly correlated with increased IMT and insulin resistance in boys but not girls, where the CCR2+ nonclassical monocyte percentage had the strongest associations (r = 0.73 and r = 0.72, respectively). The role of CCR2+ monocyte subpopulations in identifying an abnormally high IMT shows a marked sexual dimorphism, where boys seem to be at higher subclinical atherosclerosis risk than girls.

Obesity and sex interact in the regulation of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, for which a number of genetic, environmental, and lifestyle risk factors have been identified. A significant modifiable risk factor is obesity in mid-life. Interestingly, both obesity and AD exhibit sex differences and are regulated by sex steroid hormones. Accumulating evidence suggests interactions between obesity and sex in regulation of AD risk, although the pathways underlying this relationship are unclear. Inflammation and the E4 allele of apolipoprotein E have been identified as independent risk factors for AD and both interact with obesity and sex steroid hormones. We review the individual and cooperative effects of obesity and sex on development of AD and examine the potential contributions of apolipoprotein E, inflammation, and their interactions to this relationship.

Plasma kallistatin is associated with adiposity and cardiometabolic risk in apparently healthy African American adolescents

OBJECTIVE

It is generally recognized that obesity and cardiometabolic risk are more prevalent in African Americans. Kallistatin, a novel tissue kallikrein inhibitor, has anti-inflammatory and anti-oxidant properties. Thus, the goal of this study was to examine the relationships among plasma kallistatin levels, adiposity and cardiometabolic risk factors in African American adolescents.

MATERIALS/METHODS

Plasma kallistatin levels were determined in 318 apparently healthy African American adolescents (aged 14-19 years, 48.1% females) by enzyme-linked immunosorbent assay.

RESULTS

Plasma kallistatin levels did not differ between males (27.9±11.2 μg/mL) and females (26.8±11.0 μg/mL) (p=0.47). Plasma kallistatin levels were inversely correlated with percent body fat (% BF, r=-0.13, p=0.04), total cholesterol (r=-0.28, p<0.01), low density lipoprotein cholesterol (LDL, r=-0.30, p<0.01) and interleukin-6 (r=-0.14, p=0.05), but positively correlated with adiponectin (r=0.16, p=0.03) and high density lipoprotein (HDL, r=0.17, p=0.02). These correlations remained significant after adjustment for age, sex and body mass index percentiles. Stepwise multiple linear regression analysis showed that LDL cholesterol alone explained 14.2% of the variance in kallistatin, while % BF and adiponectin explained an additional 3.6% and 2.8% of the variance, respectively.

CONCLUSIONS

The present study demonstrates that plasma kallistatin levels are inversely associated with adiposity, adverse lipid profiles and inflammation in apparently healthy African American adolescents. As a potent antioxidant and anti-inflammation agent, kallistatin may also hold therapeutic promise in cardiometabolic disorders.

A genome-wide methylation study of severe vitamin D deficiency in African American adolescents

OBJECTIVES

To test the hypothesis that changes in DNA methylation are involved in vitamin D deficiency-related immune cell regulation using an unbiased genome-wide approach combined with a genomic and epigenomic integrative approach.

STUDY DESIGN

We performed a genome-wide methylation scan using the Illumina HumanMethylation 27 BeadChip on leukocyte DNA of 11 cases of vitamin D deficiency (serum 25-hydroxyvitamin D [25(OH)D] ≤ 25 nmol/L) and 11 age-matched controls ([25(OH)D] > 75 nmol/L); the subjects were African American normal-weight (body mass index <85th percentile) males aged 14-19 years. The Limma package was used to analyze each CpG site for differential methylation between cases and controls. To correct for multiple testing, the set of raw P values were converted to false discovery rates (FDRs). We also compared our findings with the recent data from Genome-Wide Association Studies of circulating 25(OH)D levels and then performed a permutation test to examine whether the "double hit" genes were randomly enriched.

RESULTS

A total of 79 CpG sites achieved raw P < .001. Of the 79 CpG sites, 2 CpG sites survived multiple testing: cg16317961 (raw P = 3.5 × 10(-6), FDR = 0.078, in MAPRE2) and cg04623955 (raw P = 5.9 × 10(-6), FDR = 0.078, in DIO3). Furthermore, 3 out of the 4 genes previously identified in the 2 Genome-Wide Association Studies were also significant at the methylation level (DHCR7: cg07487535, P = .015 and cg10763288, P = .017; CYP2R1: cg25454890, P = .040; CYP24A1: cg18956481, P = .022), reflecting significant enrichment (P = .0098).

CONCLUSION

Severe vitamin D deficiency is associated with methylation changes in leukocyte DNA. The genomic and epigenomic approach reinforce the crucial roles played by the DHCR7, CYP2R1, and CYP24A1 genes in vitamin D metabolism.

Inflammatory Markers in Pediatric Obesity

The prevalence of childhood obesity has recently peaked in the USA with ~17% of children considered obese. With the increase in adiposity that occurs with weight gain, a persistent low-grade inflammatory state is created. The most commonly studied inflammatory markers associated with obesity are the cytokines, tumor necrosis factor α and interleukin-6, and the acute-phase reactant, C-reactive protein. Understanding the relation between adiposity and inflammation is an important concept because these inflammatory markers influence insulin sensitivity, glucose metabolism, and atherosclerosis, ultimately leading to impaired health. In addition to obesity, physical inactivity is associated with elevated inflammatory markers. The literature, however, is inconsistent as to whether the association between physical activity and inflammation is independent of adiposity. In some obese children, physical fitness appears to circumvent the increase in inflammatory markers that are associated with obesity. The purpose of this review is to examine the relation between adiposity and inflammatory markers, including potential health implications and the impact of physical activity. We exposed a dearth of literature in understanding the interaction between obesity and physical activity on inflammatory markers, especially in children because their anthropometrics change. This review highlights the necessity for further research to better understand the complexity of the chronic inflammatory state associated with obesity.

Adiponectin moderates the relationship between adiposity and leptin in adolescents regardless of gender or race

OBJECTIVES

To determine gender or race differences in associations between adiposity and leptin, and whether adiponectin moderates these relationships.

METHODS

Subjects were 441 adolescents, 14-18 years old (44% black, 56% white; 50% female, 50% male). Percent body fat (%BF) was measured with dual-energy X-ray absorptiometry. Leptin and adiponectin were measured using immunoassays.

RESULTS

Among the four groups (white boys, white girls, black boys and black girls), white girls had the highest adiponectin (p = 0.0017) and black girls had the highest leptin (p = 0.0164). Percent BF and leptin were positively correlated (p = 0.0164). The %BF-leptin relationship was stronger in boys than girls (p < 0.0001). Those with lower adiponectin had a stronger %BF-leptin relationship than those with high adiponectin in the entire sample (p = 0.0220). Statistical models were adjusted for age, race, gender and the interaction between race and gender.

CONCLUSION

Our data suggest a protective metabolic interaction for adiponectin and lend additional support for obesity prevention strategies in adolescents.