Osthole regulates enzyme protein expression of CYP7A1 and DGAT2 via activation of PPARα/γ in fat milk-induced fatty liver rats

Osthole (1), an active constituent isolated from Cnidium monnieri (L.) Cusson, has been used in the treatment of diseases for many years in clinical. The aim of this present study was to determine the effect of 1 on protein expression of PPARα/γ and related target molecules such as CYP7A and DGAT protein expression in the liver of hyperlipidemic fatty liver (HFL) rats, and to investigate the possible mechanism of treating HFL.     

Effect of losartan and captopril on expression of cardiac angiotensin Ⅱ AT1 receptor mRNA in rats following myocardial infarction

目的：探讨氯沙坦（Ｌｏｓ）和卡托普利（Ｃａｐ）对大鼠心肌梗死后血管紧张素Ⅱ（Ａｎｇ）ＡＴ１受体ｍＲＮＡ表达的影响．方法：２４只梗死大鼠随机分为四组并分别用Ｃａｐ（２ｇ·Ｌ－１加水中饮用）、Ｌｏｓ（１０ｍｇ·ｋｇ－１·ｄ－１和３０ｍｇ·ｋｇ－１·ｄ－１，灌胃）及安慰剂治疗６周，假扎鼠作对照，用地高辛标记的ｃＤＮＡ探针，进行点杂交反应，检测ＡｎｇＡＴ１受体ｍＲＮＡ表达．结果：三个药物治疗组的ＡｎｇＡＴ１受体ｍＲＮＡ表达水平分别与安慰剂组比较，均显著降低（Ｐ＜００１）．三个治疗组之间的ＡｎｇＡＴ１受体ｍＲＮＡ表达水平及分别与假扎组比较，均无显著差异（Ｐ＞００５）．结论：Ｃａｐ和Ｌｏｓ均可逆转大鼠心肌梗死后ＡｎｇＡＴ１受体ｍＲＮＡ表达水平的增高．     

Correlation between activation of PPARγ and resistin downregulation in a mouse adipocyte cell line by a series of thiazolidinediones

The present study shows significant correlations between the EC₅₀ for PPARγ activation in a reporter gene cell line and resistin downregulation in mouse adipocytes, and between the IC₅₀ for resistin downregulation and the already published minimum effective dose for antihyperglycemic activity in a mouse model. These correlations indicate that PPARγ mediated downregulation of resistin might promote insulin sensitivity and that downregulation of resistin in mouse adipocytes provides an adequate and possibly more direct bioassay for screening of newly developed antihyperglycemic compounds. Because of the higher throughput of the PPARγ the resistin downregulation assays seems most suitable to be used as a second tier in a tiered screening strategy.     

Induction of the angiotensin AT2 receptor subtype expression by differentiation of the neuroblastoma × glioma hybrid,NG-108-15

In vitro differentiation of the mouse neuroblastoma-rat glioma hybrid cell line, NG-108-15, with dimethyl sulphoxide (1.5%) and low serum (0.5%), produced a marked increase in the number of angiotensin II receptors, from a level at the limit of sensitivity using labelled angiotensin II with a high specific activity ([¹²⁵I]angiotensin II), in undifferentiated cells, to a B_max of 1077 (1070–1268) fmol/mg in 5-day-differentiated cells. The affinity (K_d) of radiolabelled angiotensin II for the receptors in differentiated cells was 8.1 (7.5–10) nM. The recently available selective non-peptide antagonists. DuP 753 and PD 123177 and the peptide analogues of angiotensin II. CGP 42112A and p-aminophenylalanine⁶ angiotensin II, were used to characterize the angiotensin II receptors by competing for ¹²⁵I-[Sar¹-Ile⁸]angiotensin II binding to membranes prepared from undifferentiated and differentiated cells. The predominant angiotensin II receptor subtype expressed by undifferentiated cells was AT₁ and after differentiation AT₂. This change in receptor expression was evident 2 days after initiation of differentiation, was maximal at 4–5 days and was stable for at least 8 days. Administration of angiotensin II induced intracellular Ca²⁺ mobilization in both undifferentiated and differentiated cells. This was antagonised by the selective AT₁ antagonist. DuP 753, indicating an action at the AT₁ receptor subtype in both undifferentiated and differentiated cells. The selective AT₂ antagonist, PD 123177 was without effect on the angiotensin II induced increase intracellular Ca²⁺. This effect of DuP 753 on Ca²⁺ was specific for angiotensin II since the drug had no effect on bradykinin induced increases in intracellular Ca²⁺. Differentiation of NG-108-15 cells causes an increased expression of the AT₂ receptor. The function of this subtype of receptor remains to be determined.     

Puerarin inhibits angiotensin II-induced cardiac hypertrophy via the redox-sensitive ERK1/2, p38 and NF-κB pathways

Aim： To investigate the effects of puerarin （Pue）, an isoflavone derived from Kudzu roots, on angiotensin II （Ang II）-induced hypertrophy of cardiomyocytes in vivo and in vitro.
Methods： C57BL/6J mice were infused with Ang II and treated with Pue （100 mg·kg-1·d-1, po） for 15 d. After the treatment, systolic blood pressure （SBP） and left ventricular wall thickness were assessed. The ratios of heart weight to body weight （HW/BW） and left ventricular weight to body weight （LVW/BW） were determined, and heart morphometry was assessed. Expression of fetal-type genes （ANP, BNP and β-MHC） in left ventricles was measured using semi-quantitative RT-PCR. Mouse primary cardiomyocytes were treated with Pue （50, 100, 200 μmol/L）, then exposed to Ang II （1 μmol/L）. ROS level was examined with flow cytometry, the binding activity of NF-κB was determined using EMSA. Western blot was used to measure the levels of ERK1/2, p38 and NF-κB pathway proteins. [3H]leucine incorporation was used to measure the rate of protein synthesis.
Results： Oral administration of Pue significantly suppressed Ang II-induced increases in the myocyte surface area, HW/BW, LVW/BW, SBP and left ventricular wall thickness. Furthermore, Pue significantly suppressed Ang II-induced increases in ANP, BNP and β-MHC expression in the left ventricles in vivo. Treatment of cardiomyocytes with Pue （50–500 μmol/L） did not affect the viability of cardiomyocytes in vitro. Pretreatment of cardiomyocytes with Pue dose-dependently inhibited Ang II-induced increases in ROS production, NF-κB binding activity, protein synthesis and cell breadth. Furthermore, pretreatment with Pue significantly suppressed Ang II-induced activation of ERK1/2, p38 and the NF-κB pathway proteins and the expression of ANP and β-MHC in cardiomyocytes. The positive drug valsartan exerted similar effects on Ang II-induced cardiac hypertrophy in vivo and in vitro.
Conclusion： Pue attenuates Ang II-induced cardiac hypertrophy by inhibiting activation of the redox-sensitive ERK1/2, p38 and the NF-κB pathways.     

Effects of angiotensin II and its metabolites in the rat coronary vascular bed: is angiotensin III the preferred ligand of the angiotensin AT2 receptor?

Aminopeptidases metabolize angiotensin II to angiotensin-(2-8) (=angiotensin III) and angiotensin-(3-8) (=angiotensin IV), and carboxypeptidases generate angiotensin-(1-7) from angiotensin I and II. Angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin II type 1 (AT1) receptor blockers affect the concentrations of these metabolites, and they may thus contribute to the beneficial effects of these drugs, possibly through stimulation of non-classical angiotensin AT receptors. Here, we investigated the effects of angiotensin II, angiotensin III, angiotensin IV and angiotensin-(1-7) in the rat coronary vascular bed, with or without angiotensin AT1 - or angiotensin II type 2 (AT2) receptor blockade. Results were compared to those in rat iliac arteries and abdominal aortas. Angiotensin II, angiotensin III and angiotensin IV constricted coronary arteries via angiotensin AT1 receptor stimulation, angiotensin III and angiotensin IV being approximately 20- and approximately 8000-fold less potent than angiotensin II. The angiotensin AT2 receptor antagonist PD123319 greatly enhanced the constrictor effects of angiotensin III, starting at angiotensin III concentrations in the low nanomolar range. PD123319 enhanced the angiotensin II-induced constriction at submicromolar angiotensin II concentrations only. Angiotensin-(1-7) exerted no effects in the coronary circulation, although, at micromolar concentrations, it blocked angiotensin AT1 receptor-induced constriction. Angiotensin AT2 receptor-mediated relaxation did not occur in iliac arteries and abdominal aortas, and the constrictor effects of the angiotensin metabolites in these vessels were identical to those in the coronary vascular bed. In conclusion, angiotensin AT2 receptor activation in the rat coronary vascular bed results in vasodilation, and angiotensin III rather than angiotensin II is the preferred endogenous agonist of these receptors. Angiotensin II, angiotensin III, angiotensin IV and angiotensin-(1-7) do not exert effects through non-classical angiotensin AT receptors in the rat coronary vascular bed, iliac artery or aorta.     

The PPARγ agonist,rosiglitazone, attenuates airway inflammation and remodeling via heme oxygenase-1 in murine model of asthma

Aim:

Rosiglitazone is one of the specific PPARγ agonists showing potential therapeutic effects in asthma. Though PPARγ activation was considered protective in inhibiting airway inflammation and remodeling in asthma, the specific mechanisms are still unclear. This study was aimed to investigate whether heme oxygenase-1 (HO-1) related pathways were involved in rosiglitazone-activated PPARγ signaling in asthma treatment.

Methods:

Asthma was induced in mice by multiple exposures to ovalbumin (OVA) in 8 weeks. Prior to every OVA challenge, the mice received rosiglitazone (5 mg/kg, po). After the mice were sacrificed, the bronchoalveolar lavage fluid (BALF), blood samples and lungs were collected for analyses. The activities of HO-1, MMP-2 and MMP-9 in airway tissue were assessed, and the expression of PPARγ, HO-1 and p21 proteins was also examined.

Results:

Rosiglitazone administration significantly attenuated airway inflammation and remodeling in mice with OVA-induced asthma, which were evidenced by decreased counts of total cells, eosinophils and neutrophils, and decreased levels of IL-5 and IL-13 in BALF, and by decreased airway smooth muscle layer thickness and reduced airway collagen deposition. Furthermore, rosiglitazone administration significantly increased PPARγ, HO-1 and p21 expression and HO-1 activity, decreased MMP-2 and MMP-9 activities in airway tissue. All the therapeutic effects of rosiglitazone were significantly impaired by co-administration of the HO-1 inhibitor ZnPP.

Conclusion:

Rosiglitazone effectively attenuates airway inflammation and remodeling in OVA- induced asthma of mice by activating PPARγ/HO-1 signaling pathway.     

Inhibition of VCAM-1 expression on mouse vascular smooth muscle cells by lobastin via downregulation of p38, ERK 1/2 and NF-κB signaling pathways

Atherosclerosis is a chronic inflammatory disease, the progression of which is associated with the increased expression of cell adhesion molecules on vascular smooth muscle cells (VSMCs). Lobastin is a new pseudodepsidone isolated from Stereocaulon alpinum, Antarctic lichen, which is known to have antioxidant and antibacterial activities. However, the nature of the biological effects of lobastin still remains unclear. In the present study, we examine the effect of lobastin on the expression of vascular cell adhesion molecules (VCAM-1) induced by TNF-α in the cultured mouse VSMC cell line, MOVAS-1. Pretreatment of VSMCs for 2 h with lobastin (0.1–10 μg/ml) concentration-dependently inhibited TNF-α-induced protein expression of VCAM-1. Lobastin also inhibited TNF-α-induced production of intracellular reactive oxygen species (ROS). Lobastin abrogated TNF-α-induced phosphorylation of p38 and ERK 1/2, but not JNK, and also inhibited TNF-α-induced NK-κB activation. In addition, lobastin suppressed TNF-α-induced IκB kinase activation, subsequent degradation of IκBα and nuclear translocation of p65 NF-κB. Our results indicate that lobastin downregulates the TNF-α-mediated induction of VCAM-1 in VSMC by inhibiting the p38, ERK 1/2 and NF-κB signaling pathways and intracellular ROS generation. Thus, lobastin may be an important regulator of inflammation in the atherosclerotic lesion and a novel therapeutic drug for the treatment of atherosclerosis.     

Telmisartan prevents the progression of renal injury in daunorubicin rats with the alteration of angiotensin II and endothelin-1 receptor expression associated with its PPAR-γ agonist actions

Angiotensin II (Ang II) receptor blocker (ARB) suppresses the progression of kidney disease. However, there is limited information regarding the nephroprotective effect of ARB in daunorubicin (DNR)-induced nephrotoxicity in rats. We examined the alteration of the renal Ang II and endothelin-1 (ET-1) receptor expression and the action of telmisartan, an ARB, on DNR-induced nephrotoxicity. Sprague-Dawley rats were treated with a cumulative dose of 9 mg/kg DNR (i.v.). Telmisartan was administered orally every day for 6 weeks. DNR rats showed nephrotoxicity as evidenced by worsening renal function, which was evaluated by measuring protein in urine, levels of urea and creatinine in serum, lipid profiles, malondialdehyde level, and the glutathione peroxidase activity in kidney tissue. These changes were reversed by treatment with telmisartan, which resulted in significant improvement in renal function. Furthermore, telmisartan increased nephrin protein expression, and down-regulated renal expression of Ang II and its receptor Ang II type I. Renal protein expressions of ET-1 and its receptor ET-receptor type A were increased in DNR rats, and treatment with telmisartan attenuated these increased expressions. Telmisartan mediated a further increase in the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ). In addition, the expressions of cyclooxygenase-2 and cellular adhesion molecules were increased in DNR rats, which were attenuated by telmisartan. In conclusion, telmisartan has a protective effect on DNR-induced nephrotoxicity through Ang II and ET-1, with the alteration of their receptor expressions, which is associated with its anti-inflammatory and anti-oxidant effects at least in part through PPAR-γ agonistic actions.     

2,3,4',5-Tetrahydroxystilbene-2-O-β-d-glucoside inhibits angiotensin II-induced cardiac fibroblast proliferation via suppression of the reactive oxygen species-extracellular signal-regulated kinase 1/2 pathway

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Modulation of NF-κB activation by resveratrol in LPS treated human intestinal cells results in downregulation of PGE2 production and COX-2 expression

Resveratrol is a natural phytoalexin present in a variety of plant species, such as grapes and red wine, that is well known for its anti-inflammatory effects. In addition, a cancer chemotherapeutic activity of resveratrol has been described. Here we evaluated the effect of resveratrol on COX-2 and prostaglandin E₂ production in human intestinal cells Caco-2 cells treated with lipopolysaccharide (LPS). Resveratrol concentration-dependently inhibited the expression of COX-2 mRNA in the LPS-treated cells, as well as protein expression, resulting in a decreased production of PGE₂. In order to investigate the mechanisms through which resveratrol exhibited these anti-inflammatory effects, we examined the activation of IκB in LPS-stimulated intestinal cells. Results demonstrated that resveratrol inhibited the translocation of NF-κB p65 subunits from the cytosol to the nucleus, which correlated with its inhibitory effects on IκBα phosphorylation and degradation. These results suggest that the down-regulation of COX-2 and PGE₂ by resveratrol may be related to NF-κB inhibition through the negative regulation of IKK phosphorylation in intestinal cells.     

Aleglitazar, a dual PPARα and PPARγ agonist for the potential oral treatment of type 2 diabetes mellitus

PPARγ and PPARα are nuclear receptors mainly involved in the regulation of glucose homeostasis and lipid levels, respectively. Aleglitazar, being developed by Roche Holding, is a dual agonist for PPARγ and PPARα for the potential simultaneous treatment of hyperglycemia and dyslipidemia in patients with type 2 diabetes mellitus (T2DM). In preclinical studies, aleglitazar decreased non-fasted glucose levels, increased glucose clearance and improved insulin resistance, while also increasing HDL-cholesterol and decreasing LDL-cholesterol levels in serum. In phase I and II clinical trials in patients with T2DM, aleglitazar demonstrated beneficial antidiabetic activities and had a higher antihyperglycemic efficacy than pioglitazone (a PPARγ agonist). Aleglitazar improved the lipid profile in patients and decreased levels of cardiovascular markers of inflammation and clotting. The observed adverse events were characteristic of either PPARγ or PPARα agonists; however, when compared to pioglitazone-PPARγ-mediated effects, such as edema and weight gain, these were less severe. PPARγ-mediated adverse events on bone have not been measured and should be addressed in the future. The PPARα-mediated adverse effects on renal function are of concern and are a primary endpoint of ongoing phase II clinical trials in patients with T2DM. A phase III clinical trial was also ongoing in patients with T2DM who had recently experienced a cardiac event.     

Neutrophil elastase induces inflammation and pain in mouse knee joints via activation of proteinase‐activated receptor‐2

Background and Purpose

Neutrophil elastase plays a crucial role in arthritis. Here, its potential in triggering joint inflammation and pain was assessed, and whether these effects were mediated by proteinase‐activated receptor‐2 (PAR2).

Experimental Approach

Neutrophil elastase (5 μg) was injected into the knee joints of mice and changes in blood perfusion, leukocyte kinetics and paw withdrawal threshold were assessed. Similar experiments were performed in animals pretreated with the neutrophil elastase inhibitor sivelestat, the PAR2 antagonist GB83, the p44/42 MAPK inhibitor U0126 and in PAR2 receptor knockout (KO) mice. Neutrophil elastase activity was also evaluated in arthritic joints by fluorescent imaging and sivelestat was assessed for anti‐inflammatory and analgesic properties.

Key Results

Intra‐articular injection of neutrophil elastase caused an increase in blood perfusion, leukocyte kinetics and a decrease in paw withdrawal threshold. Sivelestat treatment suppressed this effect. The PAR2 antagonist GB83 reversed neutrophil elastase‐induced synovitis and pain and these responses were also attenuated in PAR2 KO mice. The MAPK inhibitor U0126 also blocked neutrophil elastase‐induced inflammation and pain. Active neutrophil elastase was increased in acutely inflamed knees as shown by an activatable fluorescent probe. Sivelestat appeared to reduce neutrophil elastase activity, but had only a moderate anti‐inflammatory effect in this model.

Conclusions and Implications

Neutrophil elastase induced acute inflammation and pain in knee joints of mice. These changes are PAR2‐dependent and appear to involve activation of a p44/42 MAPK pathway. Blocking neutrophil elastase, PAR2 and p44/42 MAPK activity can reduce inflammation and pain, suggesting their utility as therapeutic targets.

Linked Articles

This article is part of a themed section on Inflammation: maladies, models, mechanisms and molecules. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2016.173.issue-4

Abbreviations

IVM

intravital microscopy

LASCA

laser speckle contrast analysis

PAR

proteinase‐activated receptor

TRPV

transient receptor potential vanilloid

VCAM

vascular cell adhesion molecule

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