Urinary 8-hydroxy-2′-deoxyguanosine as a novel biomarker of inflammatory activity in patients with cardiac sarcoidosis

Background: Inflammation and oxidative stress play a crucial role in the pathogenesis of cardiac sarcoidosis (SAR). We investigated whether urinary (U) 8-hydroxy-2'-deoxyguanosine (8-OHdG)-an oxidative DNA damage marker-was related to SAR inflammatory activity. Methods: U-8-OHdG levels were measured in 31 SAR patients, classified as active (n=17) or non-active (n=14) based on F-18-fluorodeoxyglucose positron emission tomography-computed tomography (F-18-FDG-PET/CT), 28 dilated cardiomyopathy (DCM) patients, and 30 controls. In active SAR patients, U-8-OHdG levels were reexamined and compared with F-18-FDG-PET/CT results at 6 months after corticosteroid treatment to assess therapeutic response. Results: Immunohistochemical examination of left ventricle (LV) autopsy samples from SAR patients revealed positive 8-OHdG staining in cardiomyocyte nuclei from LV sections showing F-18-FDG accumulation on PET/CT, while serum 8-OHdG levels were significantly higher in the coronary sinus than in the aortic root only in active SAR patients. U-8-OHdG levels in SAR patients were higher than those in controls, and significantly higher in active SAR patients than in non-active SAR and DCM patients. U-8-OHdG was a powerful predictor of active SAR in receiver operating characteristic curve analysis (AUC, 0.98; 95% CI, 0.94-1.02; optimal cutoff value, 13.1 ng/mg creatinine), with a sensitivity of 88.2% and a specificity of 92.9%. U-8-OHdG levels in responders significantly decreased at 6 months after corticosteroid treatment initiation, in proportion with the decrease in the focal cardiac uptake of F-18-FDG. Conclusions: U-8-OHdG is a potentially clinically useful biomarker for evaluating inflammatory activity and monitoring the effectiveness of corticosteroid therapy in SAR patients. (C) 2015 Elsevier Ireland Ltd. All rights reserved.