Background: Human NADPH oxidase 5 (NOX5) is expressed and functionally active in peripheral blood mononuclear cells (PBMCs) . In those with diabetes, there is increased NOX5 expression in atherosclerotic plaques with associated coronary artery disease (CAD) and within the glomeruli in kidney biopsies. We hypothesise that NOX5 expression in circulating PBMCs is increased in patients with diabetes, particularly in those with comorbid unstable CAD and chronic kidney disease (CKD) .
Methods: 55 males aged 33-83 years underwent elective or emergency coronary angiography/angioplasty at the Alfred Hospital Catheter Laboratory. PBMCs from whole blood were processed for flow-cytometry to measure NOX5 protein. In parallel, NOX5 expression was measured in PBMCs by qPCR. In vitro, human macrophages (THP-1) were incubated in normal (5 mM) and high glucose (25 mM) . NOX5 expression and inflammatory markers were measured by qPCR.
Results: NOX5 protein expression in PBMCs was primarily driven by expression in monocytes (CD 45+/CD14+ cells) and was increased in diabetic and non-diabetic patients with CKD (28.7±4.2 vs. 17.3±1.7 AU; p=0.0038) and in diabetic patients with CKD versus without CKD (27.5±4.1 vs. 14.6±2.3 AU; p=0.012) . CAD with acute presentation was associated with increased NOX5 expression versus elective presentation (25.9±2.9 vs. 16.8±1.9 AU; p=0.0085) , particularly in diabetic patients presenting acutely versus electively (29.1±4.2 vs. 13.9±2.4 AU; p=0.0025) . A 4-fold upregulation of NOX5 gene was observed in patients with CKD versus without CKD irrespective of diabetes or CAD (p=0.018) . In vitro, there was a 2-fold increase in NOX5, TNF-α and IL-6 expression in THP-1 cells exposed to high glucose.
Conclusion: CKD and unstable CAD appear to be key factors for increased NOX5 expression in circulating PBMCs. Measurement of NOX5 in PBMCs may serve as a valuable prognostic biomarker and attractive therapeutic target in patients with clustering diabetic complications.
T.J.Block: None. K.Sourris: None. W.Khan: None. P.Kantharidis: None. J.C.Jha: None. M.E.Cooper: Advisory Panel; Bayer AG, Merck Sharp & Dohme Corp., Consultant; Boehringer Ingelheim International GmbH, Research Support; Novo Nordisk, Speaker's Bureau; AstraZeneca, Servier Laboratories. J.Shaw: None. K.Jandeleit-dahm: None.