P720Atheroprotective effects of 17beta-estradiol are mediated by PPARgamma in human coronary artery smooth muscle cells

Background

17β-estradiol (E2) mediates vasculoprotection in various preclinical and clinical models of atherosclerosis and neointimal hyperplasia. However, the molecular mechanisms underlying these effects are still not fully elucidated. Previous studies have demonstrated the essential role of the peroxisome-proliferator-activated-receptor-γ (PPARγ) in mediating vasculoprotective effects of E2 in vivo. The aim of the current study was to investigate whether PPARγ is implicated in mediating vasculoprotective mechanisms of E2 in human coronary artery smooth muscle cells (HCASMC).

Methods

Primary HCASMC were purchased and stimulated with E2 [10 nM], the selective estrogen receptor α (ERα) agonist propylpyrazole triol (PPT) [50 nM] and the selective ERα antagonist methyl-piperidino-pyrazole (MPP) [1 μM], respectively. Changes in PPARγ mRNA and protein expression upon stimulation of ERα were assessed by qPCR and Western blot analyses. Nuclear PPARγ protein expression and DNA binding affinity was assessed after the isolation of the nuclear protein fraction. Hereafter, HCASMC were incubated with E2, PPARγ-antagonist GW9662 [1 μM – 30 μM], or both. HCASMC proliferation was assessed by nuclear BrdU staining and reactive oxygen species (ROS) formation was assessed by L-012- and DCF-DA assays.

Results

E2 significantly increased PPARγ expression in HCASMC (1.95±0.41 –fold; n=5; p=0.0335). This effect was mimicked by ERα agonist PPT (1.63±0.27 –fold; n=7; p=0.0489) and was abrogated by co-incubation with ERα antagonist MPP (1.17±0.18 –fold; n=3; pvs. control >0.05). Nuclear PPARγ expression was enhanced by E2 (1.53±0.16 –fold; n=4; pvs. control = 0.0074; Fig. 2A) whereas PPARγ's DNA binding activity to PPRE remained unchanged upon stimulation with E2 (0.94±0.11 –fold; n=4; pvs. control >0.05). Pharmacological inhibition of PI3K/Akt by LY294002 abrogated E2-induced expression of PPARγ (0.24±0.09 –fold; n=3; pvs. E2 = 0.0017), arguing for a PI3K/Akt-dependent activation by E2. The role of PPARγ in mediating vasculoprotective effects of E2 was assessed in functional assays using PPARγ-antagonist GW9662. E2 diminished HCASMC proliferation which was restored by GW9662. While E2 only slightly decreased ROS production by HCASMC, GW9662 significantly increased ROS levels (1,036±169 RLU x s–1 x cell–1 versus 561±99 RLU x s–1 x cell–1; n=5–6; p=0.0287).

Conclusion

In summary, the present study identifies PPARγ as a downstream mediator of E2-related atheroprotective effects in HCASMC. 17β-estradiol regulates vascular PPARγ-expression in HCASMC via the ERα receptor and the PI3K/Akt pathway. PPARγ agonism might be a promising therapeutic strategy to prevent cardiovascular events in postmenopausal women with depleted E2 plasma levels.

Acknowledgement/Funding

This work was supported by the Bonfor program of the University of Bonn [grant number O-109.0057 to JJ].

Hands-free speech after surgical voice rehabilitation with a Provox® voice prosthesis: experience with the Provox FreeHands HME tracheostoma valve® system

Excellent results have been reported with the use of voice prostheses for the rehabilitation of laryngectomees. Patients, however, consider it a disadvantage that the tracheostoma must be closed manually for speech production. This limits their ability to simultaneously communicate by gesture or to work with both hands. An automatic tracheostoma valve helps patients overcome this problem. We describe a prospective clinical trial evaluating our experience with the Provox FreeHands HME Automatic Tracheostoma Valve system. Twenty-four laryngectomees were randomly selected from the patients who had undergone laryngectomy at the ENT Department. Immediately, after 4 weeks and 6 months later having been fitted with a Provox FreeHands HME, the patients were asked to complete a questionnaire in order to assess their satisfaction, voice quality, wearing comfort, fixation, potential problems, and the effectiveness of the HME cassette. In addition, we investigated relevant voice quality parameters including dynamics range, frequency range of the speaking voice, and maximum phonation time. Seven patients discontinued the study due to problems of securing the valve to the skin (four patients) or recurrent cancer (three patients). Ten of the remaining 17 patients wore the valve daily for an average of 8.4 h. A total of 88% of the patients considered it a great advantage to be able to speak without having to use their hands. With the Provox FreeHands HME, maximum phonation time was 8.7 (+/-6.2) s and the dynamic range was 21.9 (+/-5.8) decibels. The results show that the Provox FreeHands HME Automatic Tracheostoma Valve system not only allows hands-free speech but is also associated with excellent compliance and good voice rehabilitation.