Stress and Body Mass Index Each Contributes Independently to Tumor Necrosis Factor-α Production in Prepubescent Latino Children

Abstract

This investigation extended prior work by determining if stress and body mass index (BMI) contributed independently to tumor necrosis factor-α (TNF-α) levels among prepubescent Latino children and if sex and family history of type 2 diabetes mellitus (T2DM) modified these relationships. Data were collected in South Florida from 112 nondiabetic school-aged Hispanic children, of whom 43.8% were obese (BMI ≥ 95th percentile) and 51.8% presented with a family history of T2DM. Stressful life events were assessed via parental report using a life events scale. Plasma TNF-α levels were determined with enzyme-linked immunosorbent assay. The relative contributions of stress and BMI with TNF-α levels and the potential interaction effects of sex and family history of T2DM were analyzed with multiple linear regression analyses. Stress and BMI each accounted for a significant proportion of the unique variance associated with TNF-α. The association between stress and TNF-α was not modified by sex or family history of T2DM. These findings implicate BMI and stress as independent determinants of TNF-α (an inflammatory cytokine and adipocytokine) among Latino children. Future investigations should examine the potential roles of exercise, nutritional status, age, and growth hormone in explicating the relationship between TNF-α production and psychosocial distress and risk for infection among obese children. Keywords TNF-α; Children; BMI; StressObesity has reached pandemic proportions worldwide. Recent data had indicated that obesity has doubled in developed and developing nations (Ogden, Flegal, Carroll, & Johnson, 2002). In the United States, 16% of children and teenagers between 6 and 19 years old (more than 9 million) have been determined as obese, defined as placing above the 95th reference percentiles of body mass index (BMI), adjusted for age and sex (Ogden et al., 2002), with a disproportionate representation of Latino and African American children (Goran, 2001). These numbers remain concerning in light of the associations that have been established between childhood overweight and obesity (as reflected by greater BMI), with increased childhood morbidity, including type 2 diabetes mellitus (T2DM) and insulin resistance syndrome, hypertension, dyslipidemia, left ventricular hypertrophy, atherosclerosis, proteinuria, Daniels et al., 2005). Although obesity has been recognized as one of the easiest medical conditions to recognize, it has remained one of the most difficult to treat, with an annual cost estimated at 100 billion dollars in the United States alone (Wang & Dietz, 2002). These significant costs, with regard to actual dollars as well as the significant noted physical and psychological burden, have provided the impetus to identify pathophysiological markers associated with childhood obesity.As an inflammatory cytokine, tumor necrosis factor-α (TNF-α) has been implicated in the pathogenesis of medical complications secondary to obesity, including insulin resistance and T2DM (Hotamisligil, 2000), coronary morbid...

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