Ps-c26-12: significance of podocyte dna damage and glomerular dna methylation in ckd with proteinuria

Objective: Previously we have reported that altered DNA methylation is associated with DNA damage repair in podocytes in CKD, including diabetic nephropathy or IgA nephropathy (Cell Rep 2019, Sci Rep 2020). This study is aim to investigate the association of podocyte DNA damage and DNA methylation with clinical manifestations and renal prognosis in various types of kidney diseases, which has not been adequately investigated. Design and Method: Patients diagnosed with minor glomerular abnormalities (MGA, n = 33), membranous nephropathy (MN, n = 9) or diabetic nephropathy (DN, n = 10), following kidney biopsy at Keio University Hospital from 2015 to 2017 were included. We evaluated podocyte DNA double strand breaks (DSBs) using both long-distance PCR of nephrin gene and γH2AX immunostaining, and glomerular DNA methylation levels by immunostaining of 5mC, and examined the relationship between clinical parameters of patients, and DNA damage and methylation. Results: In MGA patients, both podocyte DNA damage and glomerular DNA methylation was associated with the amount of proteinuria. Moreover, glomerular DNA methylation was also associated with 3-year eGFR decline. We also examined in DN patients, in which podocyte DNA damage has been found to be involved in our previous study. It was demonstrated that podocyte DSBs were associated with a decline in eGFR over 6 months, whereas glomerular DNA methylation was associated with 2 year- and 3 year-eGFR decline. In addition, samples from MN patients were evaluated, in which activation of DNA repair pathways in the glomeruli has been suggested. Interestingly, the association of DNA DSBs or DNA methylation with proteinuria or kidney function was not indicated in MN. Conclusions: To our knowledge, this is the first study to demonstrate the possible association of podocyte DNA damage and glomerular DNA methylation with kidney function and its decline in MGA patients, whereas it was not observed in MN patients, despite a limitation of small sample size. Focusing on podocyte DNA damage and following DNA methylation changes may lead us to novel approaches to estimate renal prognosis in addition to traditional evaluation of renal biopsy as well as to develop novel therapeutic targets in specific types of CKD.