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Objective: chronic kidney disease progress to kidney failure, pathological changes showed glomerulosclerosis and tubulointerstitial fibrosis. The high degree of renal interstitial fibrosis with the degree of renal dysfunction, Guchang interstitial fibrosis as a reliable indicator of the extent of the evaluation of kidney disease progression. Complex mechanisms of development of renal interstitial fibrosis and tubular epithelial myofibroblasts fibroblast transdifferentiation (tubular epithelial-myofibroblast transdifferentiation, TEMT) play an important role in its development [1]. Erythropoietin EPO (erythropoietin, EPO) the endogenous cytokines secreted by the kidneys, and the main role is to regulate proliferation and differentiation by promoting survival of erythroid progenitor cells in the bone marrow, red blood cells, widely used in clinical chronic kidney treatment failure in patients with anemia. Recent study found, EPO is a multifunctional cytokine, to increase tissue oxygen in addition to regulating erythropoietin, EPO also has anti-apoptotic, anti-inflammatory, antioxidant, promote angiogenesis, and promote cell proliferation and anti-tumor . Foreign research reports, EPO can induce heme oxygenase -1 (Heme oxygenase-1, HO-1) expression increased, attenuated oxidative stress relieve tubulointerstitial injury and macrophage infiltration play a renal protective effects [2 ]. In medium lacking HO-1 strains cultured renal tubular epithelial cells, renal tubular epithelial cell transdifferentiation significantly enhanced, smooth muscle actin expression and increased renal fibrosis and tubular epithelial cell transdifferentiation [3]. In this study, a rat model of unilateral ureteral obstruction (unilateral ureteral obstruction, UUO) study to observe the pathological changes of kidney tissue, and to detect changes in their hemoglobin by immunohistochemical methods TGF-β1, α-SMA, HO- expression changes, and the application of recombinant human erythropoietin hormone (recombinant human erythropoietin, rh-EPO) to intervene, and to further explore the drug to improve renal interstitial fibrosis and its possible mechanism for clinical prevention and treatment of chronic kidney the progress of the disease provided the theoretical basis of the experimental. Methods: clean healthy male Wistar rats 54, body weight (180 ± 20) g, were randomly divided into three groups: sham operation group (A), unilateral ureteral ligation group (B) of rh-EPO intervention group ( Group C), 18. Postoperative days 3, 7, 14, were killed, and turn each group were randomly divided into N3, N7, N14 group, n = 6. All rats in temperature (23 ± 2) ° C, relative humidity of (55 ± 2)% free eating water rats in both groups B, C with 10% chloral hydrate 0.8 ~ 1 ml of anesthetized by intraperitoneal injection, spinal open at 0.5cm incision the left margin, looking to the left along the left kidney pole ureter ligation of two in the upper 1/3 on the 4th line, then cut the ureter from prevent retrograde infection, establish UUO rats model. Group A but not only free ureter ligation. The postoperative rats are normal consumption of water. Group C rats rh-EPO300IU/Kg (diluted to about 0.5ml) subcutaneously once / every other day; A and group B rats with saline injected subcutaneously once / every other day, three groups were preoperative injected subcutaneously three days the (preoperative injection rh-EPO was twice) to after three days, 7 days, 14 days after weighing cut the femoral artery rats were sacrificed and specimens from blood specimens sent to quickly remove the left kidney, according to the coronal longitudinal incision, the renal tissue in 4% paraformaldehyde fixative, embedded in paraffin, 3μm and 5μm slices were prepared. Light microscope, HE, Masson staining observed renal histopathological changes, immunohistochemical staining Determination of renal tubular interstitial HO-1, α-SMA expression of TGF-β1 in semi-quantitative analysis of the results of the application of image analysis system. The experimental results are expressed as mean ± standard deviation (x ± s) single-factor analysis of variance was used to compare groups, application SPSS13.0 statistical analysis software for statistical analysis of the experimental data, P lt; 0.05 as statistically significant . Results: 1, general observation: visible group A normal kidney size and shape, the color is dark red; B, C two sets of the obstructed kidney three days significantly enlarged color lighter, sac sexy, containing brown turbid liquid, renal parenchyma thinning, pelvis expansion, calyceal papilla compression, the fornix the nipple becomes blunt, into concave papillary atrophy. With time, these changes are more apparent. 2, HE staining showed that: A group of rats were normal renal tissue structure change. Group B rats 3 days after the tubular mild expansion, a small number of interstitial monocyte and lymphocyte infiltration; 7 days visible tubular dilated epithelial cell degeneration, edema, or necrosis, renal interstitial inflammatory cell infiltration increased interstitial significant increase in the width, occasionally atrophy tubular; 14 days of the disease increased, the visible diffuse tubular basement membrane thickening shrinkage tubule basement membrane varying degrees of fault, more cortex and outer medulla, atrophy of tubular, The interstitial lymphatic monocyte infiltration, fibrosis obvious. Compared with the same period in group B, group C rat renal tubular dilatation, interstitial mononuclear cells and the degree of infiltration of lymphocytes decreased significantly, the results were statistically significant (P lt; 0.05). Compared with the same period in group A, group C rats tubular dilatation, interstitial mononuclear cells with still higher degree of lymphocyte infiltration (P lt; 0.05). 3, Masson staining showed no obvious abnormalities: A group of rat renal tubular interstitial. Group B rat renal tubular expansion over time, increased renal interstitial width, increased collagen fibers stain deepened, compared with the same period in group B, and C group rat renal tubular interstitial fibrosis significantly reduced (P lt; 0.05) tubulointerstitial fibrosis is still higher than the same period in group A (P lt; 0.05). 4, blood test results: hemoglobin value of the treatment group compared with the model group and the sham group, the difference was not significant significance (P gt; 0.05). 5, immunohistochemical results show: the sham group, HO-1, α-SMA, TGF-β1 in renal tubular epithelial cells in a small amount of expression; Group B and Group C, along with the extension of the time of obstruction HO-1 expression was significantly reduced, but that the two groups at each time point of HO-1 expression was significantly higher than that in group A (P lt; 0.05); compared with group B, group C of HO-1 expression in each time point was significantly higher (P lt; 0.05). Group B and group C, α-SMA, TGF-β1 in each time phase point increased with the extension of the time of obstruction more obvious level, the strongest expression to 14 days, the C group than in group B at the same time point expression were significantly reduced (P lt; 0.05), but each group phase point were significantly higher than group A (P lt; 0.05). In addition to the expression of the three factors in group A, group was statistically significant (P gt; 0.05), the three groups in the group between the two groups were statistically differences (P lt; 0.05). Conclusion: 1, unilateral ureteral obstruction in rats, with obstruction time extension, showing the renal interstitium inflammatory cell infiltration, tubular continuous expansion, atrophy, necrosis, renal interstitial relative area widened renal interstitial fibrosis heavier; decline in renal interstitial HO-1 expression, and increased expression of TGF-β1, α-SMA. 2, application of rh-EPO induced HO-1 expression, inhibition of TGF-β1, α-SMA expression to reduce the infiltration of inflammatory cells, reduce the renal interstitial fibrosis; rh-EPO hemoglobin level does not affect the Group C, comparison between groups statistically significant. 3, rh-EPO induced HO-1 expression play a renal protective effect may be part transdifferentiation by inhibiting renal tubular epithelial cells, inhibition of renal interstitial fibrosis realized.
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