Abstract: Abstract Objective: To observed the Toll-like receptor 4 (TLR4) expression in the process of renal interstitial fibrosis (RIF), and therapeutically effect of fucoidan polysaccharide sulfate (FPS) thereof. Methods: Fifty-four rats were randomly divided into three groups，sham operation (SOR)，unilateral ureteral ligation obstruction model group (UUO) and FPS treatment group (FPS). Rats were sacrificed in batches and specimens were collected at 2, 4 and 6 weeks after operation. The levels of serum creatinine (Scr), blood urea nitrogen (BUN) and HE stain were observed. The expressions of TLR4 and NF-ΚB in renal tissues were detected by immunohistochemical method. Results: There were no expressions or only slight expression of TLR4 and NF-ΚB in kidneys of SOR group. The renal fibrosis was found, and positive expressions of TLR4 and NF-ΚB in UUO group compared with that of SOR group (P<0.05). The expressions of TLR4 and NF-ΚB were gradually increased with extension of obstruction and the progress of the renal fibrosis. The expressions of TLR4 and NF-ΚB were decreased in FPS group than those of UUO group (P<0.05), which decreased levels of Scr, BUN and renal fibrosis. Conclusion: FBS alleviated renal fibrosis by regulating the expression of TLR4.

Key words: Fucoidan polysaccharide sulfate, Unilateral ureteral obstruction, Renal interstitial fibrosisi, Toll-like receptor 4, Nuclear transcription factor-ΚB