Anti-fibrogenic effect of PPAR-? agonists in human intestinal myofibroblasts.

ABSTRACT:

Background

Intestinal fibrosis is a serious complication of inflammatory bowel disease, including Crohn's disease and ulcerative colitis. There is no specific treatment for intestinal fibrosis. Studies have indicated that peroxisome proliferator-activated receptor- ? (PPAR-?) agonists have anti-fibrogenic properties in organs besides the gut; however, their effects on human intestinal fibrosis are poorly understood. This study investigated the anti-fibrogenic properties and mechanisms of PPAR-? agonists on human primary intestinal myofibroblasts (HIFs).

Methods

HIFs were isolated from normal colonic tissue of patients undergoing resection due to colorectal cancer. HIFs were treated with TGF-?1 and co-incubated with or without one of two synthetic PPAR-? agonists, troglitazone or rosiglitazone. mRNA and protein expression of procollagen1A1, fibronectin, and ?-smooth muscle actin were determined by semiquantitative reverse transcription-polymerase chain reaction and Western blot. LY294002 (Akt inhibitor) was used to examine whether Akt phosphorylation was a downstream mechanism of TGF-?1 induced expression of procollagen1A1, fibronectin, and ?-smooth muscle actin in HIFs. The irreversible PPAR-? antagonist GW9662 was used to investigate whether the effect of PPAR-? agonists was PPAR-? dependent.

Results

Both PPAR-? agonists reduced the TGF-?1-induced expression of ?-smooth muscle actin which was integrated into stress fibers in HIFs, as determined by actin microfilaments fluorescent staining and ?-smooth muscle actin-specific immunocytochemistry. PPAR-? agonists also inhibited TGF-?1-induced mRNA and protein expressions of procollagen1A1, fibronectin, and ?-smooth muscle actin. TGF-?1 stimulation increased phosphorylation of downstream signaling molecules Smad2, Akt, and ERK. TGF-?1 induced synthesis of procollagen1A1, fibronectin, and ?-smooth muscle actin through a phosphatidylinositol 3-kinase/Akt-dependent mechanism. PPAR-? agonists down regulated fibrogenesis, as shown by inhibition of Akt and Smad2 phosphorylation. This anti-fibrogenic effect was PPAR-? independent.

Conclusions

Troglitazone and rosiglitazone suppress TGF-?1-induced synthesis of procollagen1A1, fibronectin, and ?-smooth muscle actin in HIFs and may be useful in treating intestinal fibrosis.

SUBMITTER: Koo JB 

PROVIDER: S-EPMC5463383 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature