PPARγ激动剂对腹膜透析相关性急性腹膜炎大鼠PPARγ、Toll样受体4表达及STAT1信号活化的影响

Effects of PPARγ agonist on the expression of PPARγ, toll-like receptor 4 and STAT1 signal protein activation in rats with peritoneal dialysis-related acute peritonitis

目的观察过氧化物酶体增殖物活化受体γ（PPARγ）激动剂罗格列酮和15脱氧前列腺素J2（15d—PGJ2）对脂多糖（LPS）诱导大鼠腹膜透析相关性急性腹膜炎模型腹膜组织PPARγ、Toll样受体4（TLR4）表达、STAT1活化及腹腔局部炎性反应的影响。方法24只雄性SD大鼠随机分成4组，每组6只。对照组：腹腔注入4．25％葡萄糖乳酸盐腹膜透析液（简称腹透液，90ml／kg）；LPS组：LPS 1mg／kg腹腔注入4h后，再注入腹透液；罗格列酮＋LPS组（罗格列酮组）：罗格列酮20mg·kg^-1·d^-1灌胃预处理3d，注入LPS及腹透液；15d—PGJ2＋LPS组（15d—PGJ2组）：15d—PGJ2 0．3mg·kg^-1·d^-1腹腔注入预处理3d，注入LPS及腹透液。注入腹透液4h后处死大鼠，留取腹水、壁层及脏层腹膜组织。ELISA法检测腹水中IL-6浓度。常规行腹膜组织Masson染色和腹水白细胞计数。RT—PCR检测腹膜组织PPARγ、TLR4 mRNA的表达；Western印迹法检测腹膜组织PPARγ、TLR4、磷酸化（p）-STAT1、STAT1蛋白的表达。结果LPS组大鼠腹水IL-6浓度[268．53（201．87～335．19）ng／L]高于对照组[147．62（130．60—164．64）ng／L）]（P〈0．01）；罗格列酮组大鼠腹水IL-6浓度[110．20（77．60～142．80）ng／L]低于LPS组（P〈0．05）。与对照组比较，LPS组大鼠腹膜组织明显水肿，腹膜组织PPARγ、TLR4 mRNA及蛋白表达均显著增强（P〈0．05）。与LPS组相比，罗格列酮组大鼠腹膜组织水肿明显减轻，PPARγ、TLR4 mRNA表达显著增高（P〈0．05），但其蛋白表达显著减弱（P〈0．05）。15d—PGJ2组大鼠腹膜组织水肿明显减轻，PPARγ mRNA及其蛋白表达均显著减弱（均P〈0．05），TLR4 mRNA表达显著增强（P〈0．01），但其蛋白表达减弱（P〈0．05）。各组间腹水白细胞计数差异无统计学意义。罗格列酮、15d—PGJ2均明显上调LPS诱导的p-STAT1表达（P〈0．01）。结论罗格列酮和15d—PGJ2可负性调节LPS诱导的大鼠急性腹膜炎性反应，并对LPS信号通路中相关功能蛋白起一定的调控作用。

Objective To explore the effects of peroxisome proliferator-activated receptorγ （PPARγ） agonist rosiglitazone and 15-deoxy-delta-12,14-prostaglandin J2 （15d-PGJ2） on the expression of PPARγ, toll-like receptor 4 （TLR4） and the activation of STAT1 as well as the local inflammation reaction of abdominal cavity in sprague dawley （SD） rats with peritoneal dialysis-related acute peritonitis induced by lipopolysaccharide （LPS）. Methods Twenty-four male SD rats were equally randomized to four groups（n=6 each）： control group, injected with 4.25% dextrose peritoneal dialysate （PDF） via abdominal cavity（90 ml/kg）; LPS group, injected with LPS（1 mg/kg） via abdominal cavity 4 hours later follewed by PDF injection; rosiglitazone plus LPS group （Rosi group）, preconditioned with rosiglitazone （20 mg ·kg^-1 ·d^-1） by intragastric way for 3 days, then injected with LPS and PDF via abdominal cavity; 15d-PGJ2 plus LPS group （15d-PGJ2 group）, preconditioned with 15d-PGJ2 （0.3 mg ·kg^-1 ·d^-1）via abdominal cavity injection for 3 days, then injected with LPS and PDF via abdominal cavity. The rats were killed 4 hours after PDF injection, IL-6 level in abdominal dropsy was determined by ELISA. Peritoneum tissue was stained by Masson. Leucocyte count in abdominal dropsy was performed. The mRNA expression of PPARγ and TLR4 in peritoneum tissue was determined by RT-PCR; the protein expression of PPARγ, TLR4, p-STAT1 and STAT1 in peritoneum tissue was analyzed by Western blot. Results IL-6 level of abdominal dropsy in LPS group [median 268.53 （range 201.87-335.19） ng/L] was significantly higher than that of control group [median 147.62 （range 130.60-164.64） ng/L] （P〈0.01）. The IL-6 level of abdominal dropsy in Rosi group [median 110.20 （range 77.60-142.80） ng/L] was significantly lower than that of LPS group （P〈0.05）. Compared to that of control group, the edematous degree of peritoneum in LPS group was significantly severer, meanwhile, mRNA and proteins expression of PPARγ and TLR4 in rat peritoneum were also significantly higher （P〈0.05, P〈0.01）. Compared to that of LPS group, the edematous degree of peritoneum in Rosi group was lighter, the expression of PPARγ and TLR4 mRNA was significantly up-regulated （P 〈0.05）, meanwhile their proteins expression was down-regulated （P〈0.05）; and in 15d-PGJ2 group, the edematous degree of peritoneum, the expression of PPARγ mRNA and protein was also decreased （P〈0.05）, but TLR4 mRNA expression was up-regulated （P〈0.01）, however, its protein expression was down-regulated （P〈0.05）. There were no significant differences in leucocyte count of abdominal dropsy among the four groups. The p-STAT1 expression in the rats peritoneum induced by LPS was markedly increased by both rosiglitazone and 15d-PGJ2 （P〈0.01）. Conclusions Both rosiglitazone and 15d-PGJ2 can down-regulate the inflammatory reaction in rat peritonitis induced by LPS, which may be involved in modulating the expression of associated functional protein during LPS signal pathway.