Pioglitazone inhibits angiotensin II-induced senescene of endothelial progenitor cell

Abstract

We investigated whether a peroxisome proliferator-activated receptor (PPAR) agonist would effect the angiotensin II (Ang II)-induced senescence of endothelial progenitor cells (EPCs). EPCs were isolated from peripheral blood and characterized. Both reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were used to assess gp91phox expression and angiotensin type 1 receptor (AT1R) levels. Immunofluorescence of nitrotyrosine provided evidence of peroxynitrite formation. Our data indicate that Ang II increased the expression of gp91phox mRNA, which was significantly diminished by pioglitazone, a PPARγ agonist. Western blotting revealed that Ang II stimulated an increase in the gp91phox protein, whereas co-treatment with ploglitazone significantly reduced this increase. In addition, pioglitazone also inhibited Ang II-induced peroxynitrite formation. Interestingly, pioglitazone decreased the expressions of AT1R mRNA and protein. The exposure of cultured EPCs to Ang II (100 nmol/L) significantly accelerated the rate of senescence compared to that of the control cells during 14 d in culture, as determined by acidic β-galactosidase staining. Ang II-induced EPC senescence was significantly inhibited by co-treatment with ploglitazone. Because cellular senescence is critically influenced by telomerase, which elongates telomeres, we also measured telomerase activity by means of PCR-ELISA-based assay. The results showed that Ang II significantly diminished telomorase activity, and this effect was significantly abolished by co-treatment with pioglitazone. In conclusion, pioglitazone inhibited Ang II-induced senescence of EPCs via down-regulation of the expression of AT1R.