In CKD patients, our recent publication identified HP, an endogenous metabolite, mediated renal fibrosis via AHR signaling pathway.26 Treatment with two concentrations of IAld significantly suppressed mRNA expression of AHR and its downstream four target genes in HP-induced HK-2 cells (Fig. 9j), which were accompanied by significantly inhibiting AHR nuclear translocation (Fig. 9k, l). This evidence concerns the gene AHR and renal fibrosis.