新型免疫调节剂FTY720对单侧输尿管梗阻大鼠肾间质纤维化的影响

目的 探讨新型免疫调节剂FTY720对单侧输尿管梗阻（UUO）大鼠肾间质纤维化的影响。 方法 将45只SD大鼠随机分为假手术组,模型组和FTY720治疗组（UUO＋FTY720）（每组n=15)。FTY720治疗组于术前3 d给予FTY720 0.5 mg·kg-1·d-1，灌胃，每日1次，直至处死动物，模型组和假手术组给予等量生理盐水同法处理。3组分别于术后7、14和21 d平行处死5只大鼠，并收集血清和24 h尿液，观察肾功能和24 h尿蛋白变化。取梗阻侧肾脏行组织学检查，观察肾间质纤维化程度和炎性细胞浸润情况。用免疫组化方法检测肾组织中α-平滑肌肌动蛋白（α-SMA）、胶原-Ⅲ型（COL-Ⅲ）的表达水平。结果 24 h尿蛋白定量：术后14 d模型组为(15.5±1.5 ) mg·d-1，FTY720治疗组为(9.7±1.7) mg·d-1，较模型组明显降低（P<0.05）。术后7、14和21 d，模型组血清肌酐（SCr）水平分别为（123.0±15.8)μmol·L-1、（65.9±6.1）μmol·L-1和（51.4±6.9） μmol.·L-1，FTY720治疗组SCr分别为（41.8±4.5） μmol·L-1、（39.5±7.9）μmol·L-1和（38.5±4.5）μmol·L-1，均较模型组明显降低（P<0.05），FTY720治疗组与假手术组SCr水平差异无统计学意义。术后7和14 d，模型组BUN分别为（16.1±3.2）mmol·L-1和（10.7±1.7）mmol·L-1，FTY720治疗组BUN分别为（8.1±1.0）mmol·L-1和（7.0±0.8）mmol·L-1，均较模型组明显降低（P<0.05）。病理学检查显示，FTY720治疗组肾间质浸润细胞较模型组明显减少，纤维化程度明显减轻。免疫组化结果显示，α-SMA表达在假手术组中仅限于血管，而在FTY720治疗组和模型组，表达明显增多，可见于肾小管和间质细胞，但FTY720治疗组中表达要弱于模型组。假手术组各个时间点肾间质中可见少量COL-Ⅲ表达，模型组手术后7、14和21 d COL-Ⅲ表达明显增强，主要集中于肾小管间质病变明显区域,FTY720治疗组表达则明显减少。结论 FTY720可以明显减轻单侧输尿管梗阻后大鼠肾间质纤维化的程度，减少肾间质炎性细胞浸润，在一定程度上可抑制肾小管上皮细胞转分化和细胞外基质的积聚，对肾功能有一定的保护作用。

A novel immunomodulator, FTY720, can inhibit renal interstitial fibrosis in rats with unilateral ureteral obstruction

Objective FTY720 is a novel immune modulating drug which obtained through structural modification of ISP-1, an immunosuppressive substance newly purified from Cordyceps sinensis , a Chinese herb traditionally used in the treatment of renal diseases. In recent years, the role of FTY720 in the immune mediated glomerulonephritis has been demonstrated, but its effects on renal interstitial fibrosis, a major determinant for prognosis, remain uncertain. The present study is aimed to examine the role of FTY720 in the inhibition of renal interstitial fibrosis in rats with unilateral ureteral obstruction(UUO). Methods Forty-five male SD rats were randomly divided into sham-operated(SHAM), operated UUO and UUO treated with FTY720 (UUO+FTY720) groups. Unilateral ureteral obstruction was induced in SD rats by ligation of the left ureter 0.5 mg·kg-1·d-1 of FTY720 or saline was administrated through daily gavage started three days before the operation until being sacrificed. Five rats in each group were sacrificed 7, 14 and 21 days after UUO or Sham-surgery. In order to investigate if renal fibrosis closely correlates with renal insufficiency, 24-hour urine protein, blood urea nitrogen (BUN) and serum creatinine were determined. The renal tubular interstitial fibrosis lesion and the expression of α-SMA and COL-Ⅲ were detected by pathdogical examine and immunohistochemistry and scored . Results The amount of 24 hours urine protein was (9.7±1.7) mg·d-1 at day 14 after operation in FTY720 treated group, much lower than that in UUO group, which was (15.5±1.5 ) mg·d-1at the same time (P<0.05). Serum creatinine was （123.0±15.8) μmol·L-1,（65.9±6.1）μmol·L-1,（51.4±6.9）μmol·L in UUO group at days 7,14,21 , respectively and （41.8±4.5）μmol·L-1（39.5±7.9）μmol·L-1,（38.5±4.5）μmol·L-1 in FTY720 treated group at days 7,14,21 , respectively. The level of creatine in FTY720 treated group were significantly lower than that in UUO group. The Blood urea nitrogen was (16.1±3.2）mmol·L-1,（10.7±1.7）mmol·L-1 in UUO group and （8.1±1.0 ）mmol·L-1,（7.0±0.8）mmol·L-1 in FTY720 treated group at days 7,14 respectively. The levels of urea nitrogen was significantly lower in FTY720 group than that in UUO group (P<0.05). The renal pathological evaluation indicated that the number of infiltrated inflammatory cells in renal interstitial was fewer in FTY720 group than that in UUO group, and the score of renal interstitial fibrosis was lower in FTY720 group than that in UUO group. Immunohistochemistry study revealed that α-SMA expression was limited to vessels in SHAM group, but extended to renal tubules and interstitium in UUO and FTY720 treated group, while relatively weaker expression was observed in FTY720 group than in UUO group. Some collagen Ⅲ expression was found in SHAM group, which was much enhanced in UUO group at days 7,14,21 and mainly distributed in renal interstitium, the expression in FTY720 group was also increased compared to SHAM group, but much lower than that in UUO group. Conclusions Novel immunomodulator FTY720 can obviously inhibit infiltration of inflammatory cell , transdifferentiation of renal tubule cell , extracellular matrix accumulation and interstitial fibrosis, thus prevent renal disease progression.