Reduced sRAGE Production and ADAM10 Gene Expression in Peripheral Blood Samples of Diabetic Nephropathy Patients

Introduction: Excessive signalling via the Receptor for Advanced Glycation End products (RAGE) is implicated in inflammatory renal damage in Diabetic Nephropathy (DN). RAGE signaling is modulated by its soluble form (sRAGE) that arises due to ectodomain cleavage catalysed by A Disintegrin and Metalloproteinase 10 (ADAM10). The sRAGE functions as a decoy and competes with RAGE for binding to the cognate ligand.

Aim: The aim of this study was to evaluate sRAGE and ADAM10 gene levels in peripheral blood samples of Diabetic Nephropathy patients.

Materials and Methods: The present observational study was conducted in the Department of General Medicine, RL Jalappa Hospital and Research Centre, Kolar, Karnataka, India, between January 2019 to April 2020. Study comprised of three groups: group 1 of 30 DN patients; group 2 of 28 Type II Diabetis Mellitus (T2DM) patients without microvascular complications and group 3 comprised of 30 healthy volunteers. Blood samples obtained from the study participants were cultured for 24 hours along with insulin treatment or a suitable control. sRAGE levels were measured in the conditioned media by Enzyme Linked Immunosorbent Assay (ELISA) technique. Expression of the ADAM10 gene was measured in the cell pellet by using the quantitative real-time Polymerase Chain Reaction (PCR) technique.

Results: A total of 88 subjects were included in the study, with 30 patients in group 1 (DN, mean age 55.34±7.76 years), 28 patients in group 2 (T2DM, mean age: 55.07±7.7 years) and 30 subjects in group 3 (healthy individuals, mean age: 55±8.05 years). sRAGE levels were significantly lower in nephropathy patients when compared to healthy volunteers (p=2.5×10-9). Likewise, ADAM10 expression levels were also significantly lower in nephropathy patients when compared to healthy volunteers (p=1.3×10-4). Insulin treatment led to significantly higher sRAGE production in healthy volunteers as compared to T2DM patients (p-value 3.3×10-11). Insulin treatment leads to significant upregulation of the ADAM10 gene expression in healthy volunteers as compared to DN and T2DM.

Conclusion: Abnormal RAGE signaling in DN may arise due to diminished sRAGE production as a consequence of reduced ADAM10 expression.