Anti-AKT1 (P125) Antikörper (A26626)

Puerarin is an isoflavonoid isolated from the root of the plant Pueraria lobata and has been used as a prescribed drug in China for the treatment of cardiovascular diseases in the clinical practice. Puerarin possesses potential therapeutic activities for metabolic and cardiovascular disorders. However, little is yet known about its bioprotection against endothelial dysfunction insulin resistance involved. In this study, we established insulin resistance by palmitate stimulation in the endothelium and investigated the action of puerarin on the modulation of insulin sensitivity under the insulin resistant condition. Palmitate stimulation impaired insulin-mediated vasodilation in the rat aorta and puerarin treatment effectively restored the impaired vasodilation in a concentration-dependent manner (1, 10 and 50 μM). Palmitate stimulation evoked inflammatory response in endothelial cells. Puerarin inhibited IKKβ/NF-κB activation and decreased TNF-α and IL-6 production with the downregulation of relative gene overexpression. Palmitate stimulation impaired the insulin PI3K signaling pathway and reduced insulin-mediated NO production in endothelial cells. Puerarin attenuated PA-induced phosphorylation of insulin receptor substrate-1 (IRS-1) at S307 and effectively ameliorated insulin-mediated tyrosine phosphorylation of IRS-1. The beneficial modification of serine/tyrosine phosphorylation of IRS-1 restored downstream Akt/eNOS activation, and thereby increased insulin-mediated NO production. These results suggest that puerarin inhibits inflammation and attenuates endothelial insulin resistance in an IKKβ/IRS-1-dependent manner.

Cellular FLICE-inhibitory protein (cFLIP) is a member of the tumour necrosis factor signalling pathway and a regulator of apoptosis, and it has a role in cardiac remodelling following myocardial infarction (MI) that remains largely uncharacterised. This study aimed to determine the function of cFLIP as a potential mediator of post-infarction cardiac remodelling. Our results show diminished cFLIP expression in failing human and murine post-infarction hearts. Genetically engineered cFLIP heterozygous (cFLIP+/-, HET) mice, cardiac-specific cFLIP-overexpressing transgenic (TG) mice and their respective wild-type (WT) and non-transgenic controls were subjected to MI by permanent ligation of their left anterior descending artery. Cardiac structure and function were assessed by echocardiography and pressure-volume loop analysis. Apoptosis, inflammation, angiogenesis, and fibrosis were evaluated in the myocardium. The HET mice showed exacerbated left ventricular (LV) contractile dysfunction, dilatation, and remodelling compared with WT mice 28 days after MI. Impaired LV function in the HET mice was associated with increases in infarct size, hypertrophy, apoptosis, inflammation, and interstitial fibrosis, and reduced capillary density. The TG mice displayed the opposite phenotype after MI. Moreover, adenovirus-mediated overexpression of cFLIP decreased LV dilatation and improved LV function and remodelling in both HET and WT mice. Further analysis of signalling events suggests that cFLIP promotes cardioprotection by interrupting JNK1/2 signalling and augmenting Akt signalling. In conclusion, our results indicate that cFLIP protects against the development of post-infarction cardiac remodelling. Thus, cFLIP gene delivery shows promise as a clinically powerful and novel therapeutic strategy for the treatment of heart failure after MI.

Artemisinin (Art) is a sesquiterpene trioxane lactone from Artemisia annua L., which has been shown to affect immune responses. However, the underlying mechanism remains elusive. In this study, we examined the anti-inflammatory and immunomodulatory effects of Art in a mouse model of contact hypersensitivity (CHS), a T-cell-mediated cutaneous inflammatory reaction. The data showed that topical administration of Art could suppress CHS response and Con A-induced T cell proliferation effectively. Further experiments indicated that Art induced the generation of regulatory T cells (Tregs) and impaired the phosphorylation of AKT, associated with the up-regulation of p38 MAPK activation. Moreover, Art also exerted a strikingly inhibitory effect on IL-17 production, and diminished the level of IL-6 paralleled with an enhancement of TGF-β, which effects were coupled with a significant reduction of STAT3 activation. These data reveal that Art could effectively block CHS response in mice by inducing the generation of Tregs and suppressing the development of Th17, indicating the potential of Art to be applied as an effective therapeutic agent for treating immune-related diseases.

Previous work in our laboratory has shown that scopoletin, one of the main bioactive constituents of Erycibe obtusifolia Benth stems, exerts anti-arthritic activity in vivo partly by preventing synovial angiogenesis. The present study was performed to further investigate the anti-angiogenic potential of scopoletin, focusing on the mechanisms of action in vitro. In the aortic ring sprouting assay, scopoletin (10, 30 and 100 μM) significantly inhibited the growth of endothelial sprouts in a concentration-dependent manner. As to human umbilical vein endothelial cells (HUVECs), scopoletin could inhibit their proliferation, migration and tubule formation induced by FGF-2, especially the proliferation. It also remarkably decreased the expression of VEGF at mRNA and protein levels, and the phosphorylations of IKKα and IκB but not Akt, as well as the degradation of IκB caused by FGF-2 in HUVECs. These findings suggest that scopoletin is substantially able to attenuate FGF-2-induced angiogenesis, and it might act by directly preventing the stimulation action of FGF-2 and by indirectly decreasing the production of VEGF. Scopoletin down-regulated the VEGF expression through NF-κB rather than PI-3K/Akt signaling pathway.

Endothelial insulin resistance is tightly associated with diabetic cardiovascular complication, and it is well known that inflammation plays an important role in the development of insulin resistance. Luteolin, a flavonoid abundant in some medical and eatable plants, is a potent inhibitor of inflammation. It is also reported that luteolin exhibited some chemoprotection capability to the endothelial integrity. This study aims to clarify whether the anti-inflammatory potency of luteolin contributes to amelioration of insulin resistance in the endothelium. Palmitate (PA) stimulation markedly reduced insulin-mediated endothelium-dependent relaxation in rat aorta, while luteolin pretreatment effectively reversed the effects of palmitate in a concentration-dependent manner. PA stimulation also evoked inflammatory response in endothelial cells. When the cells were pretreated with luteolin, IKKβ phosphorylation were reduced, which, in turn, blocked the NF-κB activation through attenuating P65 phosphorylation. At the same time, it was also found that the gene over-expressions for TNF-α and IL-6 were also reduced by luteolin pretreatment. When endothelial cells were stimulated with PA, the insulin signaling cascades were impaired with reduced insulin-dependent production of NO. Again, pretreatment of luteolin could effectively reverse the effects of PA. Luteolin modulated the Ser/Thr phosphorylation of insulin receptor substrates-1 and restored downstream Akt/eNOS activation, resulting in increased NO production in the presence of insulin. In conclusion, these results suggested that luteolin ameliorated inflammation related endothelial insulin resistance in an IKKβ/IRS-1/Akt/eNOS-dependent pathway.

AIM OF THE STUDY:

Modified Si-Miao-San (mSMS) has showed anti-inflammatory potency and has been used in the clinic to treat metabolic disorders such as obesity and diabetes, but whether its anti-inflammatory activity contributes to improving insulin resistance remains to be determined. This study aims to investigate the mechanistic relationship between its anti-inflammatory activity and modulation of insulin sensitivity in free fatty acid-stimulated HepG2 cells.

MATERIALS AND METHODS:

HepG2 cells were stimulated with palmitate (PA) and the effect of mSMS on insulin mediated-glycogen synthesis and triglyceride secretion was observed. The inhibition of mSMS on gene expression of proinflammatory cytokine tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and inhibitor of NF-κB kinase-β (IKKβ) activation was investigated. In addition, the effects of mSMS on insulin signaling transduction along insulin receptor substrates-1 (IRS-1)/Akt pathway were also evaluated. Furthermore, the effect of mSMS on glucose intolerance induced by conditioned-medium derived from activated macrophages was also assessed in normoglycemic mice.

RESULTS:

Treatment of hepatocytes with PA reduced insulin sensitivity and mSMS effectively increased insulin-mediated glycogen synthesis and restored insulin inhibition of triglyceride secretion. mSMS suppressed IKKβ activation and down-regulated TNF-α and IL-6 gene over-expression, demonstrating its anti-inflammatory activity in hepatocytes. PA-evoked inflammation impaired insulin signaling cascades and mSMS improved insulin signaling transduction by modification of Ser/Thr phosphorylation of IRS-1 and downstream Akt (T308), thereby improved insulin sensitivity in hepatocytes. mSMS also improved glucose intolerance induced by inflammatory cytokines in normoglycemic mice, which further demonstrated its modulation toward insulin sensitivity in vivo.

CONCLUSIONS:

The results suggest that mSMS inhibited inflammatory response and improved insulin sensitivity in hepatocytes via an IKKβ/IRS-1/Akt-dependent pathway.

Crown Copyright © 2011. Published by Elsevier Ireland Ltd. All rights reserved.