Influence of elevated liver fat on circulating adipocytokines and insulin resistance in obese Hispanic adolescents

Authors

  • J. S. Kim,

    1. Department of Preventive Medicine, Childhood Obesity Research Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
    2. Department of Pediatrics, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, South Korea
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  • K.-A. Lê,

    1. Department of Preventive Medicine, Childhood Obesity Research Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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  • S. Mahurkar,

    1. Department of Preventive Medicine, Childhood Obesity Research Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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  • J. N. Davis,

    1. Department of Preventive Medicine, Childhood Obesity Research Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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  • M. I. Goran

    Corresponding author
    1. Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
    • Department of Preventive Medicine, Childhood Obesity Research Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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Address for correspondence: Dr MI Goran, Department of Preventive Medicine, Childhood Obesity Research Center, Keck School of Medicine, University of Southern California, 2250 Alcazar Street, CSC #200, Los Angeles, CA 90033, USA. E-mail: goran@usc.edu

Summary

Objective

We performed this study to examine the metabolic differences arising from higher liver fat accumulation in obese Hispanic adolescents, with a particular focus on circulating levels of adipocytokines and insulin resistance.

Methods

Forty-one obese Hispanic adolescents (15.3 ± 1.0 years, body mass index percentile: 97.0 ± 3.9) were assessed for: visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and hepatic fat fraction (HFF) by magnetic resonance imaging; fasting measures of serum glucose, insulin and adipocytokines; homeostasis model assessment of insulin resistance (HOMA-IR); and insulin sensitivity (SI) and the acute insulin response to glucose (AIR) by intravenous glucose tolerance test. Subjects with normal levels of HFF (below 5%; n = 25) were compared to those with HFF > 5% (n = 16).

Results

The two groups differing in HFF were similar for total body fat, VAT and SAT. The group with HFF > 5% had significantly (P < 0.05) higher interleukin-8 (IL-8) (6.1 ± 1.6 vs. 3.2 ± 0.4 pg mL−1), NGF (30.2 ± 9.9 vs. 13.9 ± 1.6 pg mL−1), HOMA-IR (8.8 ± 1.1 vs. 5.5 ± 0.5), AIR (1869 ± 206 vs. 1092 ± 165) and a tendency for lower SI (1.2 ± 0.4 vs. 2.1 ± 0.3; P = 0.06), with no significant differences in any of other factors measured.

Conclusions

These data suggest that elevated liver fat is most closely associated with elevated serum IL-8 and NGF levels as well as increased AIR and HOMA-IR. These elevated factors may play significant roles in the metabolic abnormalities associated with elevated liver fat in obese Hispanics.

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