Background: Childhood obesity predisposes to metabolic disorders. Low grade inflammation of adipose tissue (AT) associated with macrophage infiltration may lead to metabolic complications. Two macrophage activation states M1 (pro-inflammatory) and M2 (anti-inflammatory) exist in AT with surface markers CD40 (M1), CD206 (M2) and CD163 (M2). M1 polarization correlates with metabolic complications.
Objective and hypotheses: To study the expression of CD40, CD163 and CD206 in AT of lean and obese children and adolescents.
Method: Paraffin embedded subcutaneous AT microarrays were developed from surgical biopsies of 33 lean (BMI<85%) and 29 obese(BMI≥95%) prepubertal children (Groups A:2mos-7 years and B:8-12 years) and adolescents (Group C:10-15 years). The intensity and distribution of CD40, CD163 and CD206 were studied with immunohistochemistry and mean adipocyte size and total adipocyte number were estimated by image analysis (adiposoft).
Results: CD206: Most children of all age groups showed CD206+ macrophages: Group A lean showed a higher distribution vs their respective obese (P=0.024). CD163: High intensity was observed in 33.3% of lean A, 100% of lean and obese B, 71.4% of lean C and 50% of obese C (P=0.012), whereas all of the obese A showed low intensity. CD40: High intensity was observed in 50% of lean and obese A, 70% of lean B, 40% of obese B and 50% of lean C (P=0.015). CD40 was also expressed on the adipocytes and was at high intensity only on the adipocytes of lean A (37.5%) and obese A (33.3%), (P=0.012).
Conclusion: Our study confirms the presence of both M1 and M2 macrophages in early childhood. The high distribution of CD206+ macrophages and high intensity of CD163 in the younger lean prepubertal children possibly reflects a strong anti-inflammatory profile in this young age group. The high intensity of CD40 in the obese A, together with the lower distribution of CD206 and lower intensity of CD163, may put them at a higher risk for metabolic complications. The lack of CD40+ macrophages in the obese adolescents alongside the positive staining for CD206 and CD163 may maintain an anti-inflammatory protective environment in these adolescents.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology