Supplementary Material for: Untargeted DNA-Demethylation Therapy Neither Prevents Nor Attenuates Ischemia-Reperfusion-Induced Renal Fibrosis

Background: Current treatment options for chronic kidney disease (CKD) are limited and their focus is on slowing its progression by addressing comorbidities. Fibrosis, the common histopathological process in CKD, is a major therapeutic research target. In CKD, fibroblasts are terminally activated due to alterations in their DNA-methylation pattern, particularly hypermethylation. Preventing the copying of pathological DNA-methylation patterns in proliferating fibroblasts could be a new effective therapeutic strategy for treating CKD. Methods: To evaluate the therapeutic effect of short-term treatment with the DNA-methyltransferase (DNMT)-inhibitor decitabine on fibrosis (either developing or already established), male C57Bl/6 mice underwent warm unilateral ischemia-reperfusion injury. Respectively 3 days, 3 and 6 weeks after surgery, decitabine treatment (0.25 mg/kg) was initiated for 10 days after which animals were followed up to 12 weeks after ischemia. The efficacy of therapy on fibrosis was evaluated by collagen I and tgfβ gene expression and histological quantification of collagen I staining. In addition, the effect of decitabine treatment on tubular injury (Kim-1, Ngal), inflammation (TNFa, IL6), DNA-methyltransferases (Dnmt1, 3a, and 3b), and global methylation status was determined. Results: Following ischemia there was a significant increase in fibrotic, injury, and inflammatory markers as well as an increase of the various dnmts. Although decitabine treatment transiently increased renal injury and had a moderately decreasing effect on dnmt expression and on global DNA-methylation upon immediate treatment, none of the treatment regimens succeeded in preventing, attenuating, or diminishing fibrosis in the long run. Conclusion: Administration of untargeted nucleoside analogues seems unsuitable as a first-line treatment option in developing or established CKD.