Enhanced Myeloid Leukocytes in Obese Children and Adolescents at Risk for Metabolic Impairment.

Objective: We aimed to examine if myeloid leukocyte profiles are associated with metabolic impairment in children and adolescents with obesity, and if sex, age, or race influence this relationship. Methods: 282 children ages 8-17 were evaluated. Predictor measures were absolute neutrophil counts (ANC), absolute monocyte count, monocyte subtypes and C reactive protein (CRP). Outcome variables were waist circumference, fasting glucose and insulin, HOMA-IR, HbA1c (%) and lipid profiles. Pearson correlation coefficients were used to determine associations between predictor and outcome variables. Wilcoxon two-sample tests were used to evaluate differences by sex. Results: CRP (p < 0.0001), ANC (p < 0.0018), and classical monocytes (p = 0.05) were significantly higher in children with obesity. CRP, ANC and classical monocytes showed positive correlations with waist circumference, insulin, HOMA-IR and triglycerides. CRP was positively associated with ANC overall (p = 0.05). ANC demonstrated positive correlation with monocytes (p < 0.001). The associations between predictor and outcome variables were influenced by sex, race, and age. Conclusions: CRP and myeloid leukocyte populations, specifically classical monocytes and neutrophils associate with both body composition and metabolic parameters in children with obesity suggesting that these cells may play a critical role in metabolic impairment. Race, gender and age interactions between monocytes and metabolic parameters were significant.

Markers of systemic exposures to products of intestinal bacteria in a dietary intervention study.

PURPOSE: Systemic exposures to intestinal bacteria may play a role in the etiology of the chronic, low-grade inflammation that is associated with western diets. Production of lipopolysaccharide-binding protein (LBP) is one biomarker of increased exposures to intestinal bacteria. This study evaluated whether changes in diet quality could affect serum LBP. METHODS: This was a randomized, controlled trial of Mediterranean and Healthy Eating diets over 6 months in 120 healthy subjects at increased risk of colon cancer. Blood samples obtained before and after intervention were analyzed for LBP, branched-chain fatty acids characteristic of intestinal bacteria, micronutrients and cytokines. Data were analyzed for changes in LBP over time and for predictors of LBP. RESULTS: Serum concentrations of branched-chain bacterial fatty acids declined significantly in both diet groups. However, there was no significant change in mean serum LBP concentrations with either diet intervention. In serum, LBP was positively associated with CRP and negatively associated with carotenoids both before and after intervention. After intervention, LBP was predicted positively by both CRP and bacterial fatty acid concentrations in serum, and negatively by serum carotenoids and the ω3/ω6 fatty acid ratio. This model accounted for 30 % of the inter-individual variation in serum LBP after intervention. CONCLUSIONS: These results indicate that dietary intervention over 6 months was insufficient to alter serum LBP. The relationships with inflammation-related markers, however, indicate that anti-inflammatory strategies other than changes in diet quality, such as weight loss or improved fitness, may have more potential for reducing systemic markers of LPS exposures in well-nourished populations.

Differences in Hematopoietic Stem Cells Contribute to Sexually Dimorphic Inflammatory Responses to High Fat Diet-induced Obesity.

Women of reproductive age are protected from metabolic disease relative to postmenopausal women and men. Most preclinical rodent studies are skewed toward the use of male mice to study obesity-induced metabolic dysfunction because of a similar protection observed in female mice. How sex differences in obesity-induced inflammatory responses contribute to these observations is unknown. We have compared and contrasted the effects of high fat diet-induced obesity on glucose metabolism and leukocyte activation in multiple depots in male and female C57Bl/6 mice. With both short term and long term high fat diet, male mice demonstrated increased weight gain and CD11c(+) adipose tissue macrophage content compared with female mice despite similar degrees of adipocyte hypertrophy. Competitive bone marrow transplant studies demonstrated that obesity induced a preferential contribution of male hematopoietic cells to circulating leukocytes and adipose tissue macrophages compared with female cells independent of the sex of the recipient. Sex differences in macrophage and hematopoietic cell in vitro activation in response to obesogenic cues were observed to explain these results. In summary, this report demonstrates that male and female leukocytes and hematopoietic stem cells have cell-autonomous differences in their response to obesity that contribute to an amplified response in males compared with females.