Open AccessEarly elimination of uremic toxin ameliorates AKI-to-CKD transition
Author(s) -
Jia-Huang Chen,
Chia-Ter Chao,
KuanYu Hung,
ShingHwa Liu,
Der Cherng Tarng,
ChihKang Chiang
Publication year - 2021
Publication title -
clinical science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.91
H-Index - 138
eISSN - 1470-8736
pISSN - 0143-5221
DOI - 10.1042/cs20210858
Subject(s) - unfolded protein response , acute kidney injury , kidney disease , downregulation and upregulation , kidney , medicine , fibrosis , nephrectomy , endocrinology , chemistry , pharmacology , endoplasmic reticulum , biochemistry , gene
Acute kidney injury (AKI)-related fibrosis is emerging as a major driver of chronic kidney disease (CKD) development. Aberrant kidney recovery after AKI is multifactorial and still poorly understood. The accumulation of indoxyl sulfate (IS), a protein-bound uremic toxin, has been identified as a detrimental factor of renal fibrosis. However, the mechanisms underlying IS-related aberrant kidney recovery after AKI is still unknown. The present study aims to elucidate the effects of IS on tubular damage and its involvement in the pathogenesis of AKI-to-CKD transition. Our results showed that serum IS started to accumulate associated with the downregulation of tubular organic anion transporter but not observed in the small-molecule uremic toxins of the unilateral ischemia–reperfusion injury (UIRI) without a contralateral nephrectomy model. Serum IS is positively correlated with renal fibrosis and binding immunoglobulin protein (BiP) and CAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) expression induction in the UIRI with a contralateral nephrectomy model (UIRI+Nx). To evaluate the effects of IS in the AKI-to-CKD transition, we administered indole, a precursor of IS, at the early stage of UIRI. Our results demonstrated IS potentiates renal fibrosis, senescence-associated secretory phenotype (SASP), and activation of endoplasmic reticulum (ER) stress, which is attenuated by synergistic AST-120 administration. Furthermore, we clearly demonstrated that IS exposure potentiated hypoxia–reperfusion (H/R) induced G2/M cell cycle arrest, epithelial–mesenchymal transition (EMT) and aggravated ER stress induction in vitro. Finally, the ER chemical chaperon, 4-phenylbutyric acid (4-PBA), successfully reversed the above-mentioned AKI-to-CKD transition. Taken together, early IS elimination in the early stage of AKI is likely to be a useful strategy in the prevention and/or treatment of the AKI-to-CKD transition.