Exploring Molecular Signatures Associated with Inflammation and Angiogenesis in the Aqueous Humor of Patients with Non-Proliferative Diabetic Retinopathy

Abstract

Type 2 diabetes mellitus (T2DM) is a major public health concern that significantly increases the risk of diabetic retinopathy (DR), a leading cause of visual impairment worldwide. This study aimed to identify molecular markers of inflammation (INF) and angiogenesis (ANG) in the aqueous humor (AH) of patients with non-proliferative diabetic retinopathy (NPDR). We conducted an observational, multicenter, case-control study including 116 participants classified into T2DM with NPDR, T2DM without DR, and non-diabetic controls (SCG) undergoing cataract surgery. AH samples were collected intraoperatively and analyzed for 27 cytokines using multiplex immunoassay. Eighteen immune mediators were detected in AH samples, and several were significantly elevated in the NPDR group, including the interleukins (IL) -1β, -6, -8, -15, -17, as well as the granulocyte-macrophage colony stimulating factor (GM-CSF), basic fibroblast growth factor (bFGF), interferon gamma-induced protein (IP-10), macrophage inflammatory protein 1 beta (MIP-1b), monocyte chemoattractant protein-1 (MCP-1), regulated on activation, normal T cell-expressed and -secreted protein (RANTES), and the vascular endothelial growth factor (VEGF). These molecules are involved in retinal INF, blood-retinal barrier breakdown, and pathological neovascularization. Our findings reveal a distinct pro-INF and pro-ANG profile in the AH of NPDR patients, suggesting that these cytokines may serve as early diagnostic/prognostic biomarkers for DR. Targeting these molecules could provide novel therapeutic strategies to mitigate retinal damage and vision loss in diabetic patients.

Keywords: angiogenesis; aqueous humor; biomarkers; inflammation; multiplex bead-based immunoassay; non-proliferative diabetic retinopathy; retina; type 2 diabetes mellitus.

Figure 1

Levels of the pro-INF and pro-ANG mediators in the AH of the study participants displaying higher statistical significance among all study determinations. Boxplots color codes: blue corresponds to the SCG group; pink corresponds to the T2DM + NPDR group; and finally green corresponds to the T2DM-DR group. IL: interleukin; IL-1RA: the interleukin-1 receptor antagonist; bFGF: basic fibroblast growth factor; GM-CSF: granulocyte–macrophage stimulating factor; IP10: interferon gamma-induced protein 10 kDa; MCP-1: monocyte chemoattractant protein-1; MIP-1β: macrophage inflammatory protein-1 beta; RANTES: regulated on activation, normal T cell-expressed and -secreted; VEGF: vascular endothelial growth factor.

Figure 2

Flowchart of the recruitment characteristics and distribution of the study participants.