| Objective:Homocysteine is associated with many clinical diseases,whereas,the relationship between homocysteine and renal fibrosis is unknown.The aim of the present study was to investigate the mechanisms of renal fibrosis induced by plasma Hcy by detecting the level of plasma Hcy and observing the expression of NF-κB,TGF-β1 in 5/6 subtotal nephrectomized rats,and to clarify know the therapeutic efficacy and mechanisms of action of folic acid by treating with it,and then to provide rationale substructure for clinic.Methods:seventy-two heathy pure breed depuratory male Wistar rats weighing 180±10g were randomly divided into 4 group- s:sham-operated group(group-A),5/6 nephrectomy group (group-B),5/6 nephrectomy with folic acid treated group (group-C), only folic acid treated without any operation group (group-D),n=18per group.The first stage operation was performed in group B and group C,which was left partial nephrectomy including the upper and lower poles only to retain the median part of the left kidney;and they were subjected to right nephrectomy,the second stage one week later.Operations were performed twice in group A only to dissect renal envelope to dissociate renal tissue without ablating the kidney;while group D had no any operation.Group C and group D were intragastric administrated with folic acid,while Group A and group B were only intragastric administrated with normal saline,then these rats were sacrificed at days 30,60and 90 after operation.The quantition of urine protein for 24 hours,creatinine clearance rate and plasm Hcy were detected,and renal histological changes and the expression of NF-κB and TGF-β1 were observed.The results were analyzed semi-quantitatively with the pathological image analysis system.Results :①Histological results:There was no abnormality in group A and D at days 30,60and 90,and there was no significant difference among the three time points (p>0.05). In group B, compensatory hypertrophy,mesangial cell and matrix slightly hyperplasy in glomeruli were seen 30 days after operation.Renal tubular epithelial cells were granular degeneration,some of which was compensatory dilation.Mononuclear cells and lymphocytes were occasionally seen infilerated in renal interstitium;mesangial cell and matrix was obviously hyperplasic,and segmentally aggravated 60 days after operation.Granular degeneration and little focus atrophy were observed in renal tubular epithelial cells,and mononuclear cells and lymphocytes were obviously infilerated;mesangial cells and matrix were diffusely midrange hyperplasy with segmental sclerosis, granular degeneration and little focus atrophy were seen in renal tubular epithelial cells 90 days after operation.Renal interstitium was obviously infilerated by mononuclear cells and lymphocytes.There was significant difference in pathological changes between the three time points in group B(p<0.05),and compared with group B the changes were better in group C (p<0.05),and worse compared with group A at the same time point(p < 0.05);②Immunohistochemical results: The expression of NF-ΚB was observed on the cellular periphery of mesangial cells and renal tubular epithelial cells at low level in both of group A and group D at days 30,60 and 90,while the expression of TGF-β1 was observed on podocytes apart from the two kinds of cells mentioned above,and mainly on renal tubules and renal interstitium,and there was no significant difference between those at the three time points (p>0.05).In group B and C, lymphocytes and mononuclear cells were also seen in renal interstitium,and increased gradually,and significant differences among the three time points was observed(p<0.05);compared with those in group B the expression of them was lower in group C(p<0.05),and higher compared with group A at the same time point(p<0.05);③The results of plasma Hcy by enzyme-linked immunosorbent assay (Elisa):Plasma Hcy was in the right range in group A and group D at days 30,60 and 90,and there was no significant difference those at between the three time points(p > 0.05).In group B and C,it gradually increased,and there was significant difference between those at the three time points(p<0.05), compared with group B the level of plasma Hcy was lower in group C(p<0.05),and higher compared with group A at the same time point(p<0.05);④Biochemical indices results:The quantition of urine protein for 24 hours'was in the right range in group A and group D at days 30,60 and 90,and there was no significant difference between the three time points(p>0.05).In group B and C,it increased gradually,and there was significant difference between the three time points(p<0.05),compared with that in group B it was less in group C(p<0.05),and more compared with that in group A at the same time point(p<0.05)Likewise the quantition of urine protein for 24 hours', creatinine clearance was in the right range in group A and group D at days 30,60 and 90,and there was no significant difference between the three time points(p>0.05).In contrast, it decreased gradually in group B and C,and there was significant difference between the three time points(p <0.05),compared with group B it was higher in group C(p<0.05),and lower compared with group A at the same time point(p<0.05);⑤Analysis of associativity:The level of plasma Hcy had positive correlation with the level of both of TGF-β1 and NF-κB and the degree of renal fibrosis,respectively;in contrast,there was negative correlation between the level of plasma Hcy and creatinine clearance;there was positive correlation between the level of NF-κB and the level of TGF-β1; there was positive correlation between the level of NF-κB and the quantition of urine protein for 24 hours.Conclusion:The present study prompts that FA lower plasma Hcy,inhibites the expression of TGF-β1 and NF-κB,and ameliorate the degree of renal fibrosis.The results suggest that plasma Hcy participate in the process of renal fibrosis,whose mechanism is associated with the activation of NF-κB and then the activation of TGF-β1.
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