Background: Fetuin-A is a multifunctional circulating glycoprotein that can induce insulin resistance. Lately, adipose tissue has gained prominence as an effector site of fetuin-A. Although fetuin-A-induced proinflammatory polarization and migration of macrophages plays a crucial role, it remains obscure whether monocyte subsets in circulation could simulate characteristics of macrophages in adipose tissues. This study aims to investigate the correlation between monocyte subsets with fetuin-A and its relevant insulin resistance.
Results: We evaluated serum fetuin-A levels in 107 patients with type 2 diabetes (T2D). Using flow cytometry, we classified monocyte subsets into three subtypes: (a) classical, CD14++CD16-; (b) intermediate, CD14++CD16+, the most proinflammatory one; (c) and nonclassical, CD14+CD16++. We assessed the insulin resistance by the homeostasis model assessment for insulin resistance (HOMA-IR) in 68 patients without insulin injections. We observed no correlation between fetuin-A levels and classical (ρ = - 0.005; P = 0.959), intermediate (ρ = 0.022; P = 0.826), and nonclassical monocyte counts (ρ = 0.063; P = 0.516), respectively. In addition, no significant correlation was found between log (HOMA-IR) and classical (ρ = 0.052; P = 0.688), intermediate (ρ = 0.054; P = 0.676), and nonclassical monocyte counts (ρ = 0.012; P = 0.353), respectively. However, serum fetuin-A levels showed positive correlation with log (HOMA-IR) (ρ = 0.340; P = 0.007). Multiple regression analyses revealed a significant relationship between fetuin-A and log (HOMA-IR) (β = 0.313; P = 0.016), but not with monocyte subsets.
Conclusions: Monocyte subsets in circulation, including proinflammatory intermediate monocytes, were not associated with fetuin-A and insulin resistance.
Keywords: CD14; CD16; Fetuin-A; Insulin resistance; Monocyte subsets; Type 2 diabetes.