Ghrelin ameliorates atherosclerosis by inhibiting endoplasmic reticulum stress.

The effects of ghrelin, a peptide hormone, on atherogenesis are mainly beneficial. This study aimed to investigate whether ghrelin ameliorates atherosclerosis (AS) by preventing endoplasmic reticulum stress (ERS). AS was induced by a high-fat diet in ApoE-/- mice. AS lesions in aortas were detected by Oil Red O staining, and the inner diameter and intima-media thickness (IMT) of the abdominal aorta were analyzed by ultrasonography. The protein expression of the ERS markers, 78-kDa glucose-regulated protein, C/EBP homologous protein, and active caspase-12, was detected by Western blot analysis. High-fat diet-fed ApoE-/- mice showed AS lesions and increased aortic IMT. Ghrelin ameliorated these findings. Moreover, the protein expression of ERS markers was upregulated in the AS aorta and downregulated by ghrelin treatment. The above beneficial effects of ghrelin on AS and ERS were blocked by the ERS inducer, tunicamycin. In rat aortic endothelial cells, oxidized low-density lipoprotein and tunicamycin triggered ERS, which could be inhibited by ghrelin pretreatment. These results suggest that ghrelin can ameliorate activation of ERS, which may be the beneficial effect of ghrelin on AS. Ghrelin may be a new target and strategy for prevention and therapy of AS.

Bone Morphogenetic Protein-7 Antagonizes Myocardial Fibrosis Induced by Atrial Fibrillation by Restraining Transforming Growth Factor-ß (TGF-ß)/Smads Signaling.

BACKGROUND This aim of this study was to investigate the expression of BMP-7 in atrial fibrillation and illuminate the role of BMP-7 and TGF-ß/Smads signaling in myocardial fibrosis. MATERIAL AND METHODS Fibrosis of myocardial fibroblasts was induced by TGF-ß1 and the optimal condition was determined by the MTT assay. Cells with TGF-ß1 treatment were sub-divided into 4 groups: TGF-ß1 group, TGF-ß1 + Smad3 siRNA group, TGF-ß1 + BMP-7 group, and TGF-ß1 + BMP-7 + Smad1/5 siRNA group. Cells were then analyzed by detecting the expression of epithelial cadherin (E-cadherin), collagen I, alpha smooth muscle cell actin (α-SMA), and activated Smads using Western blot. Mice were injected daily with Ach-CaCl2 with or without the addition of BMP-7 and Smad1/5 siRNA over a period of 4 weeks. Cardiac functions were tested by echocardiogram assay and fibrosis was diagnosed by histopathological examination. Finally, molecule biomarkers were detected using standard procedures. RESULTS TGF-ß1 treatment significantly down-regulated E-cadherin expression and up-regulated expressions of Collagen I, α-SMA, and pSmad3 (P<0.05). The effects of TGF-ß1 treatment can be significantly suppressed by Smad3 siRNA (P<0.05). Cells in the BMP-7 group exhibited significantly higher expression levels of E-cadherin and pSmad1/5 together with lower expression levels of pSmad3, collagen I, and a-SMA (P<0.05). Moreover, Smad1/5 siRNA can substantially repress the effects of BMP-7 (P<0.05) and results from the mice model coincided with those in myocardial fibroblasts. CONCLUSIONS BMP-7 can regulate TGF-ß1/Smad3 by targeting Smad1/5 to antagonize fibrosis in myocardial fibroblasts resulting from atrial fibrillation.

Growth and toxin production of Azadinium poporum strains in batch cultures under different nutrient conditions.

Azaspiracid-2 (AZA2) is the dominant toxin produced by Azadinium poporum strains AZDY06 and AZFC22 isolated from the South China Sea. Biomass and AZA2-production were examined within batch cultures with variation in experimental concentrations of nitrate (0, 88, 882, and 2647µM) or phosphate (0, 3.6, 36, and 109µM), different nitrogen sources (nitrate and urea) and media (f/2-Si, L1-Si, and K-Si) in the present study. Growth of both strains positively responded to nitrate or phosphate nutrients, but the growth status was significantly repressed by the highest additional level of phosphate (109µM). Both AZDY06 and AZFC22 grew well with higher specific growth rates, but with shorter growth periods, within f/2-Si medium spiked with urea than that within media spiked with nitrate. L1-Si medium with relatively high concentrations of trace metals was relatively favorable to both strains of A. poporum tested here. No obvious change within the toxin profile occurred in all cultures of both strains under the various nutrient conditions, although trace amounts of some suspicious derivatives of AZA2 occurred in some cultures. AZA2 cell quotas within both strains significantly (p<0.05) increased at the stationary phase under lower additional phosphate (0 and 3.6µM). Significant differences were not found within AZA2 cell quotas in cultures with additional nitrate ranging from 0 to 2647µM. The highest AZA2 cell quota and maximum AZA2 quantity per culture volume occurred in batch culture at the stationary phase under phosphate concentrations at 3.6µM. Neither A. poporum strain exhibited significant changes in AZA2 cell quotas within f/2-Si media spiked with urea or nitrate as nitrogen sources. The AZA2 cell quota of strain AZDY06 also did not change remarkably within f/2-Si, L1-Si, and K-Si media, however the AZA2 cell quota of strain AZFC22 within L1-Si medium was significantly (p<0.05) higher than that within f/2-Si medium.