Low-Grade Inflammation Is Not Present in Former Obese Males but Adipose Tissue Macrophage Infiltration Persists

Macrophage infiltration in two subcutaneous adipose tissue depots and systemic low-grade inflammation were studied in post-obese (PO), obese (O), and control (C) subjects. Young males were recruited into PO: (n = 10, weight-loss avg. 26%, BMI: 26.6 ± 0.7, mean ±SEM kg/m²), O: (n = 10, BMI: 33.8 ± 1.0kg/m²) and C: (n = 10, BMI: 26.6 ± 0.6 kg/m²). PO and C were matched by BMI. Blood and abdominal and gluteal subcutaneous adipose tissue were obtained in the overnight fasted state. Plasma concentrations of IL-6 and CRP were higher (p < 0.05) in O than in PO and C, TNF-α was higher (p < 0.05) only in O compared to PO and IL-18 was similar between groups. The number of CD68⁺ macrophages was higher (p < 0.05) in the gluteal than the abdominal depot, and higher (p < 0.05) in O and PO compared to C in both depots. The content of CD163⁺ macrophages was similar between depots but was higher (p < 0.05) in PO compared to C and O in the gluteal depot. In post obese men with a long-term sustained weight loss, systemic low-grade inflammation was similar to non-obese controls despite a higher subcutaneous adipose tissue CD68⁺ macrophage content. Interestingly, the anti-inflammatory CD163⁺ macrophage adipose tissue content was consistently higher in post obese than obese and controls.