Rosiglitazone but not losartan prevents Nrf-2 dependent CD36 gene expression up-regulation in an in vivo atherosclerosis model

BACKGROUND: Thiazolidinediones exert anti-inflammatory and anti-oxidative roles and attenuate atherosclerosis by mechanisms partially independent of their metabolizing actions. High doses of angiotensin type 1 receptor (AT(1)R) blocker losartan (LST) seem to promote fat cell formation by preserving PPARγ activity. METHODS: C57BL/6J diet-induced atherosclerotic susceptible mice randomly received a normal or a high-fat high-cholesterol (HFHC) diet and were treated with rosiglitazone (RG), LST or a vehicle for 12 weeks. RESULTS: HFHC was associated with increased PPARγ gene expression without an over regulation of PPARγ responsive genes, whereas RG and LST treatments were found to maintain PPARγ activity without resulting in increased PPARγ gene expression. A better anti-inflammatory and antioxidant profile in mice treated with RG regarding LST was observed in spite of a similar PPARγ preserved activity. Chromatin immunoprecipitation (ChIP) assays revealed that animals under HFHC diet treated with RG showed a significant nuclear factor erythroid 2-like 2 (Nrf2)-dependent down-regulation of the expression of the CD36 gene. CONCLUSION: The PPARγ agonist RG exerts antioxidant properties that significantly reduced Nrf-2-dependent CD-36 up-regulation in mice under HFHC diet. Because LST treatment was also associated with a preserved PPARγ activity, our data suggests that these RG antioxidant effects are partially independent of its PPARγ metabolizing properties

Rosiglitazone but not losartan prevents Nrf-2 dependent CD36 gene expression up-regulation in an atherosclerosis model-1

Rescence signal levels measured of the HDL isolated from mice under control diet with respect to that obtained from mice that fed a HFHC diet after 1 day elapsed; thus the average fluorescence value obtained of the HDL from both groups was taken as "Day 1" reference value. Data are mean ± SD from thee separate experiments. (). ChIP with a PPARγ antibody of study groups were used to amplify an apo A-I promoter fragment. ChIP figures percentages indicate increments or decrements regarding C57BL/6J mice fed HFHC diet. Data of C57BL/6J mice fed chow diet was established as 100%.<p><b>Copyright information:</b></p><p>Taken from "Rosiglitazone but not losartan prevents Nrf-2 dependent CD36 gene expression up-regulation in an atherosclerosis model"</p><p>Cardiovascular Diabetology 2008;7():3-3.</p><p>Published online 26 Feb 2008</p><p>PMCID:PMC2266907.</p><p></p

PPAR mRNA relative expression in pooled liver samples from analyzed groups normalized to GAPDH expression

Results are expressed as mean ± SEM percentage of mean values obtained from equal numbers of C57BL/6J and C3He/6J mice. *P < 0.05. (). SCARB1 mRNA relative expression in liver samples from analyzed groups normalized to GAPDH expression. *P < 0.05 (). ChIP with a PPARγ antibody of study groups was used to amplify a SCARB1 promoter fragment. ChIP figures percentages indicate increments or decrements regarding C57BL/6J mice fed HFHC diet. Data of C57BL/6J mice fed chow diet was established as 100%.<p><b>Copyright information:</b></p><p>Taken from "Rosiglitazone but not losartan prevents Nrf-2 dependent CD36 gene expression up-regulation in an atherosclerosis model"</p><p>http://www.cardiab.com/content/7/1/3</p><p>Cardiovascular Diabetology 2008;7():3-3.</p><p>Published online 26 Feb 2008</p><p>PMCID:PMC2266907.</p><p></p

Triplicate measurements were taken in three animals per group before the onset of the study period (day 0), at day 1 and each 25 days elapsed after completing 100 days

Inter-group comparisons were made at day 1 and at day 100 and intra-group between days 1 and 100. Data are expressed as mean ± SD.<p><b>Copyright information:</b></p><p>Taken from "Rosiglitazone but not losartan prevents Nrf-2 dependent CD36 gene expression up-regulation in an atherosclerosis model"</p><p>http://www.cardiab.com/content/7/1/3</p><p>Cardiovascular Diabetology 2008;7():3-3.</p><p>Published online 26 Feb 2008</p><p>PMCID:PMC2266907.</p><p></p

() CD36 mRNA relative expression in pooled liver samples from analyzed groups normalized to GAPDH expression

*P < 0.05. () ChIP with an Nrf2 antibody of study groups was used to amplify a CD36 promoter fragment. ChIP figures percentages indicate increments or decrements regarding C57BL/6J mice fed HFHC diet. Data of C57BL/6J mice fed chow diet was established as 100%. () Quiascent day-5 adipocytes incubated with RG and LST were treated with ox-PACP for additional 24 h. RNA was isolated to measure adipose protein 2 by conventional PCR and CD36 expression using real-time PCR. Values were normalized to GAPDH expression. Figure bar plots represent mean ± SEM percentage from vehicle-treated cells of at least 4 experiments with duplicate measurements.<p><b>Copyright information:</b></p><p>Taken from "Rosiglitazone but not losartan prevents Nrf-2 dependent CD36 gene expression up-regulation in an atherosclerosis model"</p><p>http://www.cardiab.com/content/7/1/3</p><p>Cardiovascular Diabetology 2008;7():3-3.</p><p>Published online 26 Feb 2008</p><p>PMCID:PMC2266907.</p><p></p

(a) iNOS mRNA relative expression in pooled liver samples from analyzed groups normalized to GAPDH expression

*P < 0.05. (b) eNOS mRNA relative expression in pooled liver samples from analyzed groups normalized to GAPDH expression. Results are expressed as mean ± SEM percentage of mean values obtained from equal numbers of C57BL/6J and C3He/6J mice. *P < 0.05. (c) ChIP with a PPARγ antibody of study groups was used to amplify an iNOS promoter fragment. ChIP figures percentages indicate increments or decrements regarding C57BL/6J mice fed HFHC diet. Data of C57BL/6J mice fed chow diet was established as 100%.<p><b>Copyright information:</b></p><p>Taken from "Rosiglitazone but not losartan prevents Nrf-2 dependent CD36 gene expression up-regulation in an atherosclerosis model"</p><p>http://www.cardiab.com/content/7/1/3</p><p>Cardiovascular Diabetology 2008;7():3-3.</p><p>Published online 26 Feb 2008</p><p>PMCID:PMC2266907.</p><p></p

Rosiglitazone but not losartan prevents Nrf-2 dependent CD36 gene expression up-regulation in an atherosclerosis model-6

Rescence signal levels measured of the HDL isolated from mice under control diet with respect to that obtained from mice that fed a HFHC diet after 1 day elapsed; thus the average fluorescence value obtained of the HDL from both groups was taken as "Day 1" reference value. Data are mean ± SD from thee separate experiments. (). ChIP with a PPARγ antibody of study groups were used to amplify an apo A-I promoter fragment. ChIP figures percentages indicate increments or decrements regarding C57BL/6J mice fed HFHC diet. Data of C57BL/6J mice fed chow diet was established as 100%.<p><b>Copyright information:</b></p><p>Taken from "Rosiglitazone but not losartan prevents Nrf-2 dependent CD36 gene expression up-regulation in an atherosclerosis model"</p><p>Cardiovascular Diabetology 2008;7():3-3.</p><p>Published online 26 Feb 2008</p><p>PMCID:PMC2266907.</p><p></p