Constitutive DPP4 activity, inflammation, and microvascular reactivity in subjects with excess body weight and without diabetes

Abstract

Objective: In patients with diabetes, dipeptidyl peptidase 4 (DPP4) inhibition is associated with attenuation of inflammation and endothelial dysfunction. Here, we investigated the associations between constitutive DPP4 activity, inflammatory biomarkers, and microvascular reactivity in subjects with excess body weight without diabetes.

Methods: Forty subjects of BMI ≥ 25.0 kg/m² and without diabetes were cross-sectionally evaluated. We assessed microvascular blood flow and vasomotion by laser Doppler flowmetry, and measured at baseline, 30, and 60 min after a standardized meal: DPP4 activity, glucose, insulin, hs-CRP, TNF-α, IL-6, PAI-1, ICAM-1, and VCAM-1. HOMA-IR and HOMA-AD were used to assess insulin resistance. Linear correlations of DPP4 activity with the biomarkers of inflammation and components of microvascular function were conducted. In step further, multiple regression analyses were performed to test whether some of these variables could influence, or be influenced by, the plasma DPP4 activity.

Results: DPP4 activity was inversely associated with VCAM-1 at baseline (P < 0.05), and DPP4 activity_AUC was inversely correlated with the myogenic component_AUC of vasomotion (P < 0.05). In multiple regression analysis, HOMA-AD, IL-6, VCAM-1, PAI-1, blood flow, and vasomotion influenced DPP4 activity and explained almost 40% of the variance on it. When HOMA-AD, VCAM-1, and blood flow were placed respectively as dependent variables, DPP4 activity exerted a significant effect in all of them.

Conclusions: Constitutive DPP4 activity was associated with early markers of endothelial proinflammatory activation and microvascular function, and may have an influence and even be influenced by inflammation and microvascular blood flow in subjects with excess body weight without diabetes.

Keywords: Dipeptidyl peptidase IV; Endothelial dysfunction; Microvascular reactivity; Pre-diabetes.