Di(2-ethylhexyl) phthalate accelerates chronic kidney disease through enhanced hepatic indoxyl sulfate production and impaired renal excretion via NOX-ROS signaling

Di-(2-ethylhexyl) phthalate (DEHP), a widely used plasticizer in medical devices, has been implicated in kidney injury; however, its role in chronic kidney disease (CKD) progression remains poorly understood. Indoxyl sulfate (IS), a liver-derived uremic toxin excreted by the kidneys, is a key mediator of CKD progression. This study investigated whether DEHP aggravates CKD by disrupting IS metabolism and renal clearance. Using in vivo and in vitro models, we examined the effects of DEHP at a clinically relevant dose (1 mg/kg) on IS production, renal organic anion transporter (OAT) expression, fibrotic signaling, and renal function. The roles of peroxisome proliferator-activated receptor γ (PPARγ) and NADPH oxidase (NOX)-reactive oxygen species (ROS) signaling were evaluated using pharmacological inhibitors and siRNA knockdown. A clinical cohort of 395 CKD patients was further analyzed to assess associations between plasma DEHP and IS levels. DEHP significantly increased plasma IS, creatinine, and BUN levels and aggravated renal fibrosis in 5/6 nephrectomy mice. In the liver, DEHP upregulated PPARγ, cytochrome P450 2E1 (CYP2E1), and sulfotransferase 1A1 (SULT1A1), thereby enhancing IS production. In the kidney, DEHP suppressed OAT1 and OAT3 expression, promoting IS accumulation and tubular injury. Mechanistically, DEHP activated NOX-ROS signaling in hepatocytes and tubular cells. Inhibition of PPARγ or NOX-ROS signaling attenuated DEHP-induced hepatic CYP2E1/SULT1A1 upregulation and restored renal OAT expression. Clinically, elevated plasma DEHP levels were independently associated with higher circulating IS concentrations in CKD patients. Collectively, DEHP accelerates CKD progression by increasing IS generation and impairing renal IS excretion via PPARγ- and NOX-ROS-dependent mechanisms.