Neutrophil functions in morbidly obese subjects

Abstract

The present study aimed to determine different peripheral blood neutrophil functions in 18 morbidly obese subjects with body mass index (BMI) ranging between 35 and 69 kg/m(2) in parallel with age- and gender-matched lean controls. Peripheral blood neutrophil functions of obese subjects and matched lean controls were determined. Neutrophils of obese subjects showed significant elevation of the release of basal superoxides (P < 0.0001), formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated superoxides (P < 0.0001) and opsonized zymosan (OZ)-stimulated superoxides (P < 0.045) compared with lean controls. Interestingly, there were no differences in phorbol myristate acetate (PMA)-stimulated superoxide production by neutrophils of the obese subjects and controls. There was also a significant elevation of chemotactic (P < 0.0003) and random (P < 0.0001) migration of neutrophils from obese subjects compared with lean controls. Phagocytosis, CD11b surface expression and adherence of neutrophils from obese subjects were not significantly different from those of the lean controls. The elevated superoxide production and chemotactic activity, together with the normal phagocytosis and adherence, suggest that neutrophils from obese subjects are primed and have the capability to combat infections. However, neutrophils in the priming state may participate in the pathogenesis of obesity-related diseases.

Keywords: cell activation; chemotaxis; neutrophils; phagocytosis.

Figure 1

Superoxide production was measured in neutrophils from obese subjects or from healthy donors unstimulated or stimulated with either 5 × 10⁻⁷ M formyl-methionyl-leucyl-phenylalanine (fMLP), 1 mg/ml opsonized zymosan (OZ) or 50 ng/ml phorbol myristate acetate (PMA). Each value is a mean of two independent tests from each subject. The mean ± standard error of the mean are presented by the horizontal lines. There is a correlation (r = 0·78) between basal superoxide production secreted from unstimulated neutrophils and the body mass index.

Figure 2

Chemotactic and random migration of neutrophils towards formyl-methionyl-leucyl-phenylalanine (fMLP). Chemotactic migration towards 10⁻⁸ M fMLP and random migration were studied in neutrophils from obese patients and healthy controls. Each value is a mean of two independent tests from each subject. The mean ± standard error of the mean are presented by the horizontal lines.

Figure 3

Phagocytosis of opsonized zymosan (OZ) by neutrophils of obese subjects. Each value is a mean of two independent tests from each subject. The mean ± standard error of the mean are presented by the horizontal lines.

Figure 4

Neutrophil adherence to endothelial cells was determined in unstimulated neutrophils or stimulated neutrophils by 5 × 10⁻⁷ M formyl-methionyl-leucyl-phenylalanine (fMLP) or 50 ng/ml phorbol myristate acetate (PMA). Results are mean ± standard error of the mean of % adhered neutrophils of the subject studies.