The relationship between eosinophil and macrophage abundance in human visceral adipose tissue in healthy individuals

Animal studies have linked adipose tissue eosinophils to metabolic homeostasis through IL-4-dependent mechanisms; however, corresponding data from human VAT, particularly in healthy individuals, remain limited. We analyzed eosinophil abundance (CD45⁺CD14^-CD16^-CD15⁺) in visceral adipose tissue (VAT) obtained from 47 apparently healthy living kidney donors (31 women and 16 men). The eosinophil association with anti-inflammatory CD14⁺CD16^- and pro-inflammatory CD14⁺CD16⁺ macrophages and eosinophil distribution across perivascular adipose tissue (PVAT) and blood were investigated. Eosinophil percentage in VAT was positively correlated with the proportion of anti-inflammatory CD14⁺CD16^- macrophages (r = 0.40, 95% CI 0.19-0.61, p = 0.005). Eosinophil abundance in VAT was positively correlated with eosinophil levels in both PVAT and blood, with a stronger association observed between visceral and perivascular depots. In a multivariable linear regression model, the previously reported association between non-HDL cholesterol and the proportion of anti-inflammatory macrophages was confirmed, and high-sensitivity C-reactive protein was identified as an additional negative predictor. In the multivariable model, VAT eosinophil percentage was not independently associated with anti-inflammatory macrophage proportion (P = 0.109). Plasma IL-4 concentrations remained within a narrow range across all participants. These findings extend the limited evidence on eosinophils in human VAT and underscore the need to define their specific functions within the adipose tissue immune network, including whether and how they contribute to macrophage polarization and immunometabolic homeostasis.