S-38-4: ASSOCIATION BETWEEN DNA METHYLATION AGE OR DNA DAMAGE IN URINARY SHEDDING CELLS AND EARLY CKD

Abstract

Objective: Recent studies have identified that aggregate DNA methylation status of specific sites measures biological age, referred to as the DNA methylation clock. However, the relationship between kidney diseases and DNA methylation clock has been unclear. In this study, we aimed to investigate the association between DNA methylation age or DNA damage in urinary shedding cells and early CKD. Design and method: Individuals aged 45–81 years old, who visited Keio University Hospital for annual health check-up were enrolled. A total of 22 participants (14 males, 8 females) aged 61.6 ± 10.0 years old were eligible for this study. We evaluated a 71 CpG epigenetic age predictor, referred to as the Hannum's clock, which lacks 6 probes on the EPIC array using blood samples from the patient. 50 ml of urine samples were collected and centrifuged, and mRNA was extracted to analyze the expression of phenotypical markers and epigenetic modulators in urine derived cells by quantitative RT–PCR method as previously described. DNA was also extracted from urine derived cells, and DNA double strand breaks (DSBs) were evaluated by the quantitative long distance PCR method as previously described (Hishikawa, et al. Sci rep 2020). The association between biological aging (Hannum's clock age − chronological age) and clinical data was investigated. Results: Hannum's clock correlated with chronological age, and biological aging (Hannum's clock age − chronological age) was promoted in CKD patients (eGFR 43–59). DNA DSBs of the nephrin gene was also promoted in CKD patients. DNMT3 expression in urinary shedding cells correlated with biological aging. Conclusions: To our knowledge, this is the first study to demonstrate the possible association of biological aging measured by DNA methylation clock and CKD, especially in early stage. Podocyte DNA DSBs and urine DMNT3 expression may be a potential marker of biological aging.