HPX and acute kidney injury: For our epigenetic studies, we selected representative candidate genes from each of the four identified expression patterns: i) upregulated in AKI and CKD models, Kim-1, Ngal, Tnf, Tlr4, Timp1 and Spp1(osteopontin); ii) downregulated in AKI and CKD, Klotho (KI), Lrp5, Kmt1b (Suv39h2), Kdr, and Epo; iii) upregulated in AKI but not in CKD, Hpx, and Pnmt, Hmox1; and iv) upregulated in CKD but not in AKI, Apoe, Timp2 and Igfbp7 (Fig. 3B).