CLDN1 and chronic kidney disease: The high-dose roxadustat significantly increased the expression levels of ZO-1, occludin, claudin-1, and HIF-1α (shown in Figure 3C), while the low-dose roxadustat only increased the expression levels of occludin, claudin-1, and HIF-1α significantly (shown in Figure 3C) compared with the CKD group.