Roxadustat Attenuates the Disruption of Epithelial Tight Junction in Caco2 Cells and a Rat Model of CKD Through MicroRNA-223

Abstract

IntroductionIncreasing evidence supports the idea that the disruption of epithelial tight junction proteins (TJPs) caused by accumulation of uremia toxins, such as homocysteine (Hcy), is one of the most important mechanisms underlying the damage of intestinal barrier function (IBF) in chronic kidney disease (CKD). Since the decrease of hypoxia inducible factor-1α (HIF-1α) is reported to be involved in Hcy-induced cell injury, and the upregulation of microRNA-223 (miR-223) plays a vital protective role in the impairment of IBF in the experimental colitis, we investigated the effect of HIF-1α stabilizer roxadustat on the disruption of TJPs induced by Hcy and CKD and the underlying mechanism.MethodsChronic kidney disease was induced in rats via 5/6 nephrectomy. In a series of experiments, the rats were treated orally with roxadustat of different doses. The expression of tight junction proteins, HIF-1α, and miR-223 was analyzed in different groups by western blotting analysis, RT-qPCR techniques and immunofluorescence. A series of experiments with cultured Caco2 cells was performed.ResultsThe results showed that the expression of TJPs (occludin, claudin-1, and ZO-1) decreased significantly, accompanied by the reduction of HIF-1α and miR-223 in Hcy-treated Caco2 cells and colonic mucosa of uremic rats. The reduction of HIF-1α and miR-223 was reversed by roxadustat and the decrease of TJPs expression was attenuated in both Caco2 cells induced by Hcy and colon tissue of CKD rats. Furthermore, transfection with miR-223 mimics increased the expression of TJPs, while transfection with miR-223 inhibitor decreased their expression in Caco2 cells. MiR-223 inhibitor applied before roxadustat treatment partly diminished the effect of roxadustat on TJPs expression in Caco2 cells.ConclusionThese results indicated that roxadustat attenuated the disruption of epithelial TJPs induced by Hcy in Caco2 cells and the damage of colonic epithelium in CKD rats through the upregulation of miR-223 induced by HIF-1α. A novel insight into the IBF dysfunction in CKD was provided, and it suggests a potential therapeutic use of roxadustat for the IBF dysfunction besides anemia in CKD.

Relief Effects of Icariin on Inflammation-Induced Decrease of Tight Junctions in Intestinal Epithelial Cells

“…Active PI3K/AKT could up-regulate the expression of Claudin2 and increase intestinal permeability ( Yang et al, 2017 ). Up-regulated HIF-1α reduced the expression of Occludin, Claudin-1, and ZO-1 by unregulated miR-223 in rats and Caco-2 cells ( Qu et al, 2022 ). In Foxo4-null mice, CD4 + T cell recruitment enhanced expressions of TNF-α and IFN-γ in colonic epithelium, accompanied by decreased expressions of ZO-1 and Occludin, and increased intestinal permeability ( Zhou et al, 2009 ).…”

Tight junctions and acute kidney injury

“…Nephrotoxin‐induced AKI : In a murine model of folic acid‐induced AKI, FG‐4592 (Roxadustat) accelerated tubular repair by facilitating the recovery of tubular structural integrity and upregulating expression of ZO‐1 in TECs (Li et al, 2021b). FG‐4592 restored colonic epithelium TJ expression in CKD rats through the upregulation of miR‐223 induced by HIF‐1α (Qu et al, 2022). In a rat model of cisplatin‐induced AKI (Trujillo et al, 2016), treatment with curcumin, a polyphenol, significantly improved the expression of renal TJ proteins such as occludin and claudin‐2 and restored TJ structure by ameliorating the expression of PKCβ2 and NADPH oxidase, thus preventing the loss of cell‐cell contacts induced by cisplatin.…”