J Korean Med Sci.  2010 Jan;25(1):35-41. 10.3346/jkms.2010.25.1.35.

PPARgamma Agonist and Angiotensin II Receptor Antagonist Ameliorate Renal Tubulointerstitial Fibrosis

• Han JY
• Kim YJ
• Kim L
• Choi SJ
• Park IS
• Kim JM
• Chu YC
• Cha DR

• KMID: 1713829
• DOI: http://doi.org/10.3346/jkms.2010.25.1.35

Abstract

The peroxisome proliferator activated receptor (PPAR)gamma agonist is used as antidiabetic agent with antihyperglycemic and antihyperinsulinemic actions. Beyond these actions, antifibrotic effects have been reported. We examined antifibrotic effects of PPARgamma agonist and interaction with angiotensin receptor antagonist in the unilateral ureteral obstruction (UUO) model. After UUO, mice were divided to four groups: no treatment (CONT), pioglitazone treatment, L158809 treatment, and L158809+ pioglitazone treatment. On day 14, CONT mice showed severe fibrosis and all treated mice showed decreased fibrosis. The immunohistochmistry of PAI-1, F4/80 and p-Smad2 demonstrated that their expressions were increased in CONT group and decreased in the all treated groups compared to CONT. PAI-1 and p-Smad2 determined from Western blotting, among treated groups, was decreased compared to CONT group. The expression of TGF-beta1 from real time RT PCR showed markedly increased in the CONT group and decreased in all treated groups compared to CONT. These data suggest the pioglitazone inhibited tubulointerstitial fibrosis, however, the synergism between pioglitazone and L158809 is not clear. Considering decreased expression of PAI-1 and TGF-beta/Smad2 in the treated groups, PAI-1 and TGF-beta are likely linked to the decreased renal tubulointerstitial fibrosis. According to these results, the PPARgamma agonist might be used in the treatment of renal fibrotic disease.

Keyword

PPAR gamma; Receptors, Angiotensin; Fibrosis; Plasminogen Activator Inhibitor 1; Transforming Growth Factor Beta

MeSH Terms

*Angiotensin Receptor Antagonists
Animals
Antigens, Differentiation/metabolism
Disease Models, Animal
Fibrosis
Hypoglycemic Agents/pharmacology
Kidney/metabolism/*pathology
Male
Mice
Mice, Inbred C57BL
PPAR gamma/*agonists
Plasminogen Activator Inhibitor 1/metabolism
Smad2 Protein/metabolism
Thiazolidinediones/pharmacology
Transforming Growth Factor beta1/genetics/metabolism
Ureteral Obstruction/metabolism/pathology
Angiotensin Receptor Antagonists
Antigens, Differentiation
Hypoglycemic Agents
PPAR gamma
Plasminogen Activator Inhibitor 1
Smad2 Protein
Thiazolidinediones
Transforming Growth Factor beta1

Figure

• 

  Fig. 1 Tubulointerstititial changes in obstructed kidneys. (A) At day 5, tubulointerstitial fibrosis is slightly increased at all groups with no significant difference among groups. At day 14, CONT mice show severe progressive fibrosis and three treated groups show decreased fibrosis compared to CONT. a, sham operated kidney; b, CONT at day 5; c, pioglitazone treated group at day 5; d, L158809 treated group at day 5; e, combined treatment group at day 5; f, CONT at day 14; g, pioglitazone treated group at day 14; h, L158809 treated group at day 14; i, combined treatment group at day 14 (Masson-trichrome stain, ×200). (B) Point counting scoring of fibrosis at day 14 shows less fibrosis in all treated groups compared to CONT (Comb; combined treatment group) (*P<0.05 vs. CONT).

• 

  Fig. 2 Interstitial macrophage numbers in obstructed kidneys at day 14. CONT mice show markedly increased number of interstitial macrophages and all treated groups show decreased number of macrophages compared to CONT (*P<0.05 vs. CONT).

• 

  Fig. 3 PAI-1 protein expression by Immunohistochemical staining. (A) PAI-1 expression is identified in the cytoplasm of atrophic tubular epithelial cells, interstitial inflammatory cells and parietal epithelial cells of glomerulus. At day 5, PAI-1 expression is minimally increased with no significant difference among groups. At day 14, PAI-1 expression is increased at CONT. At pioglitazone treated group, the PAI-1 expressions is decreased comparing to CONT. a, sham operated kidney; b, CONT at day 5; c, pioglitazone treated group at day 5; d, L158809 treated group at day 5; e, combined treatment group at day 5; f, CONT at day 14; g, pioglitazone treated group at day 14; h, L158809 treated group at day 14; i, combined treatment group at day 14 (immunohistochemical staining for PAI-1, ×200). (B) Semiquantative grading of PAI-1 expression at day 14 shows significantly decreased PAI-1 expression only at the pioglitazone treated groups compared to CONT (*P<0.05 vs. CONT).

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  Fig. 4 PAI-1 protein expression by western blotting at day 14. PAI-1 expression is decreased at all treated groups compared to CONT (*P<0.05 vs. CONT).

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  Fig. 5 P-Smad2 expression by Immunohistochemical staining. P-Smad2 is detected at the nuclei of tubular epithelial cells and interstitial inflammatory cells. (A) At day 5, p-Smad2 expression of IHC at treated groups is not increased compared to normal control. Weak cytoplasm stainings are present at all groups. At day 14, p-Smad2 expression is increased at CONT. At all treated groups, the p-Smad2 expressions are decreased compared to CONT. a, sham operated kidney; b, CONT at day 5; c, pioglitazone treated group at day 5; d, L158809 treated group at day 5; e, combined treatment group at day 5; f, CONT at day 14; g, pioglitazone treated group at day 14; h, L158809 treated group at day 14; i, combined treatment group at day 14 (immunohistochemical staining for p-Smad 2, ×200). (B) Semiquantative grading of p-Smad2 expression at day 14 shows significantly decreased p-Smad2 expression at the all treated groups compared to CONT (*P<0.05 vs. CONT) .

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  Fig. 6 P-smad 2 expression by western blotting at day 14. P-Smad2 expression blotting at combined treatment group is decreased compared to CONT (*P<0.05 vs. CONT).

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  Fig. 7 Real time RT PCR for TGF-β1 at day 14. TGF-β1 expression shows markedly increased at the CONT and significantly decreases at the all treated groups compared to CONT (*P<0.05 vs. CONT).

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