Background
It has been proposed that peroxisome proliferator-activated receptor-γ (PPARγ) agonists might reduce renal fibrosis, however, several studies had contradictory results. Moreover, the possible interaction of TGF-β
1
, PPARγ, and transcription factors in renal fibrosis have not been investigated. We hypothesized that oral pioglitazone treatment would inhibit TGF-β–driven renal fibrosis and its progression, by modulating profibrotic transcription factors in TGF-β
1
transgenic mice.
Methods
Male C57Bl/6 J mice (control, CTL,
n
= 14) and TGF-β overexpressing transgenic mice (TGFβ,
n
= 14, having elevated plasma TGF-β
1
level) were divided in two sets at 10 weeks of age. Mice in the first set were fed with regular rodent chow (CTL and TGFβ,
n
= 7/group). Mice in the second set were fed with chow containing pioglitazone (at a dose of 20 mg/kg/day, CTL + Pio and TGFβ+Pio,
n
= 7/group). After 5 weeks of treatment, blood pressure was assessed and urine samples were collected, and the kidneys were analyzed for histology, mRNA and protein expression.
Results
TGF-β
1
induced glomerulosclerosis and tubulointerstitial damage were significantly reduced by pioglitazone. Pioglitazone inhibited renal mRNA expression of all the profibrotic effectors: type-III collagen, TGF-β
1
, CTGF and TIMP-1, and alike transcription factors cFos/cJun and protein expression of EGR-1, and STAT3 protein phosphorylation.
Conclusions
Oral administration of PPARγ agonist pioglitazone significantly reduces TGF-β
1
-driven renal fibrosis, via the attenuation of EGR-1, STAT3 and AP-1. This implies that PPARγ agonists might be effective in the treatment of chronic kidney disease patients.
Electronic supplementary material
The online version of this article (10.1186/s12882-019-1431-x) contains supplementary material, which is available to authorized users.