Oligo-fucoidan prevents renal tubulointerstitial fibrosis by inhibiting the CD44 signal pathway

Tubulointerstitial fibrosis is recognized as a key determinant of progressive chronic kidney disease (CKD). Fucoidan, a sulphated polysaccharide extracted from brown seaweed, exerts beneficial effects in some nephropathy models. The present study evaluated the inhibitory effect of oligo-fucoidan (800 Da) on renal tubulointerstitial fibrosis. We established a mouse CKD model by right nephrectomy with transient ischemic injury to the left kidney. Six weeks after the surgery, we fed the CKD mice oligo-fucoidan at 10, 20, and 100 mg/kg/d for 6 weeks and found that the oligo-fucoidan doses less than 100 mg/kg/d improved renal function and reduced renal tubulointerstitial fibrosis in CKD mice. Oligo-fucoidan also inhibited pressure-induced fibrotic responses and the expression of CD44, β-catenin, and TGF-β in rat renal tubular cells (NRK-52E). CD44 knockdown downregulated the expression of β-catenin and TGF-β in pressure-treated cells. Additional ligands for CD44 reduced the anti-fibrotic effect of oligo-fucoidan in NRK-52E cells. These data suggest that oligo-fucoidan at the particular dose prevents renal tubulointerstitial fibrosis in a CKD model. The anti-fibrotic effect of oligo-fucoidan may result from interfering with the interaction between CD44 and its extracellular ligands.