Research On Effect Of A Purified Laminaria Japonica Polysaccharide On Chronic Renal Failure And Vascular Calcification In Adenine-Induced Mice

Polysaccharide extracted from Laminaria japonica, as a kind of natural biological macromolecules in cells, possesses a variety of biological activities. In this paper, we examined the effect and underlying mechanism of a purified L. japonica polysaccharide (LJP61A) on the adenine-induced mice with chronic renal failure and concurrent vascular calcification in vitro and vivo experimental model.The main results obtained in this study are shown as the follows:(1) LJP61A inhibits the development of chronic renal failure in adenine-induced mice:The mice made with chronic renal failure were established using adenine. The inbibitory effects of LJP61A on chronic renal failure were studied from the aspects of body weight, biochemical and histopathological variations in serum and kidney. Histopathological examination showed that LJP61A had auxiliary protective effects on renal compensatory hypertrophy and renal tubular injury in a dose-dependent manner. Detection of serum and urine biochemical parameters showed that LJP61A could significantly reduce serum creatinine and urea nitrogen levels, correct disorders of electrolytes and protein metabolism, and thus stabilize renal function. These results suggested that LJP61A exhibited significant effect on delaying the development of chronic renal disease.(2) LJP61A inhibits the vascular calcification in adenine-induced chronic renal failure mice:The inbibitory effects of LJP61A on vascular calcification were studied using adenine-induced mice model. Pathologic observation showed that LJP61A could obviously decrease the levels of calcium, phosphorus and alkaline phosphatase activity in aorta, serum parathormone and fibroblast growth factor-23 content; Morphologic and immunohistochemical results showed that LJP61A could reduce the deposition of hydroxyapatite crystals in aortic, and increase the expression of calcium-sensing receptor on the vascular smooth muscle cells. qRT-PCR experiments showed that LJP61A caused a remarkable increase in mRNA expression of a-SMA and SM22a, which act as marker gene of vascular smooth muscle cell; and the reduction of Pit-1 mRNA levels. Meanwhile, LJP61A could significantly enhance the expression of OPG and MGP which was accompanied by the reduction of Cbfa-1, OC, RANKL and BMP-2 protein expression. According to these results, we can conclude that LJP61A exhibited significant innibitory effects on the progresses of vascular calcification in adenine-induced chronic renal failure mice.(3) LJP61A inhibites the calcification of vascular smooth muscle cell induced by β-glycerophosphate:Usingβ-GP-induced vascular smooth muscle cell model, we found that the intracellular calcification and ALP activity was significantly attenuated when the cells were treated with LJP61A at 25μg/mL. qRT-PCR experiments showed that LJP61A could significantly suppress the Pit-1 gene expression,and increase the mRNA expression of MGP、OPN、a-SMA and SM22a in MOVAS cell than those of the model group. Moreover, LJP61A caused a remarkable increase in protein expression of OPG and MGP, while inhibited the expression of Cbfa-1, OC, RANKL and BMP-2 protein were inhibited. Our findings suggest that LJP61A inhibits the conversion of vascular smooth muscle cell into osteoblast-like cell via regulating the balance between intracellular calcification promoting and inhibitory factor.