Search

Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes. Emerging evidence suggests that aberrant DNA methylation may play a critical role in the pathogenesis of diabetic complications. Yet, its involvement in DPN is not fully characterized. In this study, we performed a large-scale genome-wide methylation profiling of sural nerve samples obtained from subjects with type 2 diabetes mellitus (T2DM) using Reduced Representation Bisulfite Sequencing (RRBS). A total of 78 samples were sequenced and mapped to the human reference genome. Differential analysis was performed on two groups, identified by our previous transcriptomic analysis of the same samples, which showed significantly different HbA1c levels: Group 1 (=8.5%±1.6%) and Group 2 ( In summary, we demonstrate that type 2 diabetic patients with peripheral neuropathy and high HbA1c show distinct variations in sural nerve methylome, suggesting that DNA methylation and DPN are associated and that these associations are at least in part HbA1c-dependent. Our results provide new insights into the role of HbA1c in epigenetic variation, and identify candidate genes relevant to the pathogenesis of DPN in human sural nerves of subjects with T2DM. Disclosure K. Guo: None. S. Elzinga: None. S. Eid: None. C. Figueroa-Romero: None. B.A. McGregor: None. G. de Anda-Jáuregui: None. C. Pacut: None. E.L. Feldman: None. J. Hur: None.

Diabetic neuropathy (DN) is one of the most common complications of diabetes worldwide, affecting up to 60% of all diabetic patients. Although the pathogenesis of DN is poorly understood, it is widely accepted that reactive oxygen species (ROS) mediate in part the cellular and molecular injury observed in DN. NADPH oxidase (Nox) enzymes generate ROS and of the 7 isoforms, NOX5 is present only in man. In this study, we aimed to investigate a role for NOX5 in DN by identifying the cellular localization, methylation status and expression levels of NOX5 in cutaneous nerve fibers and sural nerve biopsies of diabetic patients. Cellular localization of NOX5, myelin basic protein (MBP) and protein gene product (PGP) 9.5 were determined in cutaneous nerve fibers of controls and subjects with DN. NOX5 methylation status and protein levels were assessed in subjects with DN that were divided into two groups based on changes in sural nerve myelinated fiber density: regenerators (showing significant nerve regeneration) and degenerators (showing significant nerve degeneration). NOX5 expression was present in deep myelinated cutaneous fibers. Bisulfite sequencing revealed that the NOX5 promoter, enriched with CpG sites, is hypomethylated in sural nerve biopsies of the degenerator cohort compared to the regenerator. The increase in NOX5 expression in degenerator sural nerves was accompanied with a decrease in MBP levels relative to the regenerator group. Our results highlight that in subjects with DN with sural nerve degeneration, there is hypomethylation of the NOX5 promoter associated with an increase in its protein expression, suggesting a potential epigenetic and mechanistic role of NOX5 in DN. Disclosure S. Eid: None. J.M. Hayes: None. K. Guo: None. C. Pacut: None. F. Mendelson: None. J. Hur: None. E.L. Feldman: None.