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 / 中华肾脏病杂志

ABSTRACT

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-regnlate the inflammatory reaction in rat peritonitis induced by LIPS, which may be involved in modulating the expression of associated functional protein during LPS signal pathway.