Obesity-associated T-cell and macrophage activation improve partly after a lifestyle intervention

Background The relation between low-grade inflammation and metabolic dysfunction in obesity is not fully explored. Objective To evaluate immune parameters in the obese state and after a lifestyle intervention program. Methods Patients with obesity (n = 87) from an academic obesity clinic were compared with controls with regard to macrophage and T-cell activation (reflected by serum levels of soluble CD163 (sCD163) and soluble IL-2 receptor (sIL-2R), respectively), and an array of cytokines, chemokines, and growth factors. In addition, these parameters and regulatory T-cells (Treg), were studied in 27 patients who followed a 75-week lifestyle intervention (dietary advice, exercise, and psychoeducation). Results Mean sIL-2R and sCD163 levels were higher in patients than controls (sIL-2R:2884 +/- 936 pg/ml vs. 2207 +/- 813 pg/ml,p = 0.001; sCD163:1279 +/- 580 pg/ml vs. 661 +/- 271 pg/ml,p < 0.0001 respectively). Patients with metabolic syndrome (MetS) had higher sCD163 than those without (1467 +/- 656 pg/ml vs. 1103 +/- 438 pg/ml). Patients had higher IL-1 beta, IL-1RA, IL-2, IL-4, IL-5, IL-6, IL-8, IL-9, IL-10, IL-15, IL-17A, MCP-1/CCL2, MIP-1 alpha/CCL3, MIP-1 beta/CCL4, G-CSF, GM-CSF, FGF, IFN-gamma, and TNF-alpha than controls, whereas VEGF-A, PDGF-BB, and eotaxin were lower. Upon intervention, sIL-2R decreased while peripheral Treg frequencies increased within the reference range (p = 0.042 andp = 0.005 respectively). The sIL-2R decrease correlated to a decrease in waist circumference (rho = 0.388,p = 0.045) and in trend to a decrease in MetS components (rho = 0.345,p = 0.078). The Treg increase was unrelated to weight loss or metabolic improvement. Mean sCD163 did not change significantly upon intervention, nor did the cytokines, chemokines, and growth factors (except IP-10/CXCL10). Conclusion In obesity, T-cell homeostasis improves after a lifestyle intervention. Immunologic alterations can occur independently of metabolic improvement.