ACE2 Deficiency Enhances Angiotensin II-Mediated Aortic Profilin-1 Expression, Inflammation and Peroxynitrite Production

Inflammation and oxidative stress play a crucial role in angiotensin (Ang) II-mediated vascular injury. Angiotensin-converting enzyme 2 (ACE2) has recently been identified as a specific Ang II-degrading enzyme but its role in vascular biology remains elusive. We hypothesized that loss of ACE2 would facilitate Ang II-mediated vascular inflammation and peroxynitrite production. 10-week wildtype (WT, Ace2+/y) and ACE2 knockout (ACE2KO, Ace2−/y) mice received with mini-osmotic pumps with Ang II (1.5 mg.kg−1.d−1) or saline for 2 weeks. Aortic ACE2 protein was obviously reduced in WT mice in response to Ang II related to increases in profilin-1 protein and plasma levels of Ang II and Ang-(1–7). Loss of ACE2 resulted in greater increases in Ang II-induced mRNA expressions of inflammatory cytokines monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-1β, and IL-6 without affecting tumor necrosis factor-α in aortas of ACE2KO mice. Furthermore, ACE2 deficiency led to greater increases in Ang II-mediated profilin-1 expression, NADPH oxidase activity, and superoxide and peroxynitrite production in the aortas of ACE2KO mice associated with enhanced phosphorylated levels of Akt, p70S6 kinase, extracellular signal-regulated kinases (ERK1/2) and endothelial nitric oxide synthase (eNOS). Interestingly, daily treatment with AT1 receptor blocker irbesartan (50 mg/kg) significantly prevented Ang II-mediated aortic profilin-1 expression, inflammation, and peroxynitrite production in WT mice with enhanced ACE2 levels and the suppression of the Akt-ERK-eNOS signaling pathways. Our findings reveal that ACE2 deficiency worsens Ang II-mediated aortic inflammation and peroxynitrite production associated with the augmentation of profilin-1 expression and the activation of the Akt-ERK-eNOS signaling, suggesting potential therapeutic approaches by enhancing ACE2 action for patients with vascular diseases

Natural radionuclide of Po210 in the edible seafood affected by coal-fired power plant industry in Kapar coastal area of Malaysia

<p>Abstract</p> <p>Background</p> <p>Po²¹⁰can be accumulated in various environmental materials, including marine organisms, and contributes to the dose of natural radiation in seafood. The concentration of this radionuclide in the marine environment can be influenced by the operation of a coal burning power plant but existing studies regarding this issue are not well documented. Therefore, the aim of this study was to estimate the Po²¹⁰concentration level in marine organisms from the coastal area of Kapar, Malaysia which is very near to a coal burning power plant station and to assess its impact on seafood consumers.</p> <p>Methods</p> <p>Concentration of Po²¹⁰was determined in the edible muscle of seafood and water from the coastal area of Kapar, Malaysia using radiochemical separation and the Alpha Spectrometry technique.</p> <p>Results</p> <p>The activities of Po²¹⁰in the dissolved phase of water samples ranged between 0.51 ± 0.21 and 0.71 ± 0.24 mBql^-1whereas the particulate phase registered a range of 50.34 ± 11.40 to 72.07 ± 21.20 Bqkg^-1. The ranges of Po²¹⁰activities in the organism samples were 4.4 ± 0.12 to 6.4 ± 0.95 Bqkg^-1dry wt in fish (<it>Arius maculatus</it>), 45.7 ± 0.86 to 54.4 ± 1.58 Bqkg^-1dry wt in shrimp (<it>Penaeus merguiensis</it>) and 104.3 ± 3.44 to 293.8 ± 10.04 Bqkg^-1dry wt in cockle (<it>Anadara granosa</it>). The variation of Po²¹⁰in organisms is dependent on the mode of their life style, ambient water concentration and seasonal changes. The concentration factors calculated for fish and molluscs were higher than the recommended values by the IAEA. An assessment of daily intake and received dose due to the consumption of seafood was also carried out and found to be 2083.85 mBqday^-1person^-1and 249.30 μSvyr^-1respectively. These values are comparatively higher than reported values in other countries. Moreover, the transformation of Po²¹⁰in the human body was calculated and revealed that a considerable amount of Po²¹⁰can be absorbed in the internal organs. The calculated values of life time mortality and morbidity cancer risks were 24.8 × 10^-4and 34 × 10^-4respectively which also exceeded the recommended limits set by the ICRP.</p> <p>Conclusions</p> <p>The findings of this present study can be used to evaluate the safety dose uptake level of seafood as well as to monitor environmental health. However, as the calculated dose and cancer risks were found to cross the limit of safety, finding a realistic way to moderate the risk is imperative.</p

Characterisation of the cancer-associated glucocorticoid system:key role of 11β-hydroxysteroid dehydrogenase type 2

Background:Recent studies have shown that production of cortisol not only takes place in several non-adrenal peripheral tissues such as epithelial cells but, also, the local inter-conversion between cortisone and cortisol is regulated by the 11β-hydroxysteroid dehydrogenases (11β-HSDs). However, little is known about the activity of this non-adrenal glucocorticoid system in cancers.Methods:The presence of a functioning glucocorticoid system was assessed in human skin squamous cell carcinoma (SCC) and melanoma and further, in 16 epithelial cell lines from 8 different tissue types using ELISA, western blotting and immunofluorescence. 11β-HSD2 was inhibited both pharmacologically and by siRNA technology. Naïve CD8 + T cells were used to test the paracrine effects of cancer-derived cortisol on the immune system in vitro. Functional assays included cell-cell adhesion and cohesion in two-and three-dimensional models. Immunohistochemical data of 11β-HSD expression were generated using tissue microarrays of 40 cases of human SCCs as well as a database featuring 315 cancer cases from 15 different tissues.Results:We show that cortisol production is a common feature of malignant cells and has paracrine functions. Cortisol production correlated with the magnitude of glucocorticoid receptor (GR)-dependent inhibition of tumour-specific CD8 + T cells in vitro. 11β-HSDs were detectable in human skin SCCs and melanoma. Analyses of publicly available protein expression data of 11β-HSDs demonstrated that 11β-HSD1 and-HSD2 were dysregulated in the majority (73%) of malignancies. Pharmacological manipulation of 11β-HSD2 activity by 18β-glycyrrhetinic acid (GA) and silencing by specific siRNAs modulated the bioavailability of cortisol. Cortisol also acted in an autocrine manner and promoted cell invasion in vitro and cell-cell adhesion and cohesion in two-and three-dimensional models. Immunohistochemical analyses using tissue microarrays showed that expression of 11β-HSD2 was significantly reduced in human SCCs of the skin.Conclusions:The results demonstrate evidence of a cancer-associated glucocorticoid system and show for the first time, the functional significance of cancer-derived cortisol in tumour progression

Aberrant expression of the S1P regulating enzymes, SPHK1 and SGPL1, contributes to a migratory phenotype in OSCC mediated through S1PR2.

Oral squamous cell carcinoma (OSCC) is a lethal disease with a 5-year mortality rate of around 50%. Molecular targeted therapies are not in routine use and novel therapeutic targets are required. Our previous microarray data indicated sphingosine 1-phosphate (S1P) metabolism and signalling was deregulated in OSCC. In this study, we have investigated the contribution of S1P signalling to the pathogenesis of OSCC. We show that the expression of the two major enzymes that regulate S1P levels were altered in OSCC: SPHK1 was significantly upregulated in OSCC tissues compared to normal oral mucosa and low levels of SGPL1 mRNA correlated with a worse overall survival. In in vitro studies, S1P enhanced the migration/invasion of OSCC cells and attenuated cisplatin-induced death. We also demonstrate that S1P receptor expression is deregulated in primary OSCCs and that S1PR2 is over-expressed in a subset of tumours, which in part mediates S1P-induced migration of OSCC cells. Lastly, we demonstrate that FTY720 induced significantly more apoptosis in OSCC cells compared to non-malignant cells and that FTY720 acted synergistically with cisplatin to induce cell death. Taken together, our data show that S1P signalling promotes tumour aggressiveness in OSCC and identify S1P signalling as a potential therapeutic target.This article is freely available via Open Access. Click on the 'Additional Link' above to access the full-text via the publisher's site.Published (Open Access

Vascular hypertrophy-associated hypertension of profilin1 transgenic mouse model leads to functional remodeling of peripheral arteries

Increased mechanical stress/hypertension in the vessel wall triggers the hypertrophic signaling pathway, resulting in structural remodeling of vasculature. Vascular hypertrophy of resistance vessels leads to reduced compliance and elevation of blood pressure. We showed before that increased expression of profilin1 protein in the medial layer of the aorta induces stress fiber formation, triggering the hypertrophic signaling resulting in vascular hypertrophy and, ultimately, hypertension in older mice. Our hypothesis is that profilin1 induced vascular hypertrophy in resistance vessels, which led to elevation of blood pressure, both of which contributed to the modulation of vascular function. Our results showed significant increases in the expression of α1- and β1-integrins (280 ± 6.3 and 325 ± 7.4%, respectively) and the activation of the Rho/Rho-associated kinase (ROCK) II pathway (260 and 350%, respectively, P < 0.05) in profilin1 mesenteric arteries. The activation of Rho/ROCK led to the inhibition of endothelial nitric oxide synthase expression (39 ± 5.4%; P < 0.05) and phosphorylation (35 ± 4.5%; P < 0.05) but also an increase in myosin light chain 20 phosphorylation (372%, P < 0.05). There were also increases in hypertrophic signaling pathways in the mesenteric arteries of profilin1 mice such as phospho-extracellular signal-regulated kinase 1/2 and phospho-c-Jun NH2-terminal kinase (312.15 and 232.5%, respectively, P < 0.05). Functional analyses of mesenteric arteries toward the vasoactive drugs were assessed using wire-myograph and showed significant increases in the vascular responses of profilin1 mesenteric arteries toward phenylephrine, but significant decreases in response toward ROCK inhibitor Y-27632, ACh, sodium nitrite, and cytochalasin D. The changes in vascular responses in the mesenteric arteries of profilin1 mice are due to vascular hypertrophy and the elevation of blood pressure in the profilin1 transgenic mice

Vascular hypertrophy and hypertension caused by transgenic overexpression of profilin 1.

We have overexpressed either the cDNA of human profilin 1 or expressed the mutant (88R/L) in the blood vessels of transgenic FVB/N mice. Reverse transcription-PCR indicated selective overexpression of profilin 1 and 88R/L in vascular smooth muscle cells. Polyproline binding showed increased profilin 1 and 88R/L proteins in transgenic mice compared with control (~30%, p 400%, p < 0.05). Tail cuff and circadian monitoring of blood pressure showed significant increases in systolic and mean arterial blood pressures of profilin 1 mice starting at age 6 months compared with controls (~25 mm Hg, p < 0.05). These results suggest that increased actin polymerization in blood vessels triggers activation of the hypertrophic signaling cascades and results in elevation of blood pressure at advanced age

Rac-Induced Left Ventricular Dilation in Thyroxin-Treated ZmRacD Transgenic Mice: Role of Cardiomyocyte Apoptosis and Myocardial Fibrosis

<div><p>The pathways inducing the critical transition from compensated hypertrophy to cardiac dilation and failure remain poorly understood. The goal of our study is to determine the role of Rac-induced signaling in this transition process. Our previous results showed that Thyroxin (T4) treatment resulted in increased myocardial Rac expression in wild-type mice and a higher level of expression in Zea maize RacD (ZmRacD) transgenic mice. Our current results showed that T4 treatment induced physiologic cardiac hypertrophy in wild-type mice, as demonstrated by echocardiography and histopathology analyses. This was associated with significant increases in myocardial Rac-GTP, superoxide and ERK1/2 activities. Conversely, echocardiography and histopathology analyses showed that T4 treatment induced dilated cardiomyopathy along with compensatory cardiac hypertrophy in ZmRacD mice. These were linked with further increases in myocardial Rac-GTP, superoxide and ERK1/2 activities. Additionally, there were significant increases in caspase-8 expression and caspase-3 activity. However, there was a significant decrease in p38-MAPK activity. Interestingly, inhibition of myocardial Rac-GTP activity and superoxide generation with pravastatin and carvedilol, respectively, attenuated all functional, structural, and molecular changes associated with the T4-induced cardiomyopathy in ZmRacD mice except the compensatory cardiac hypertrophy. Taken together, T4-induced ZmRacD is a novel mouse model of dilated cardiomyopathy that shares many characteristics with the human disease phenotype. To our knowledge, this is the first study to show graded Rac-mediated O₂·⁻ results in cardiac phenotype shift <em>in-vivo</em>. Moreover, Rac-mediated O₂·⁻ generation, cardiomyocyte apoptosis, and myocardial fibrosis seem to play a pivotal role in the transition from cardiac hypertrophy to cardiac dilation and failure. Targeting Rac signaling could represent valuable therapeutic strategy not only in saving the failing myocardium but also to prevent this transition process.</p> </div

Increased Myocardial Fibrosis in Dilated Cardiomyopathy of T4-Treated Transgenic mice.

<p>Masson's trichrome staining shows distinct interstitial fibrosis in the hearts of T4-treated transgenic hearts (<b>A</b>); Magnifications are the same for all panels. Representative bar graph showing quantitative results on total collagen deposition in mice hearts (<b>B</b>). <b>*</b> is significant change compared to untreated WT mice, <b>**</b> is significant change compared to T4-treated and untreated WT mice, <b>#</b> is significant change compared to untreated transgenic mice, and <b>+</b> is significant change compared to T4-treated transgenic mice (n = 8/group).</p