Activation of angiotensin-converting enzyme 2 (ACE2) attenuates allergic airway inflammation in rat asthma model.

Angiotensin-I converting enzyme (ACE) is positively correlated to asthma, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS) and is highly expressed in lungs. ACE2, the counteracting enzyme of ACE, was proven to be protective in pulmonary, cardiovascular diseases. In the present study we checked the effect of ACE2 activation in animal model of asthma. Asthma was induced in male wistar rats by sensitization and challenge with ovalbumin and then treated with ACE2 activator, diminazene aceturate (DIZE) for 2weeks. 48h after last allergen challenge, animals were anesthetized, blood, BALF, femoral bone marrow lavage were collected for leucocyte count; trachea for measuring airway responsiveness to carbachol; lungs and heart were isolated for histological studies and western blotting. In our animal model, the characteristic features of asthma such as altered airway responsiveness to carbachol, eosinophilia and neutrophilia were observed. Western blotting revealed the increased pulmonary expression of ACE1, IL-1ß, IL-4, NF-κB, BCL2, p-AKT, p-p38 and decreased expression of ACE2 and IκB. DIZE treatment prevented these alterations. Intraalveolar interstitial thickening, inflammatory cell infiltration, interstitial fibrosis, oxidative stress and right ventricular hypertrophy in asthma control animals were also reversed by DIZE treatment. Activation of ACE2 by DIZE conferred protection against asthma as evident from biochemical, functional, histological and molecular parameters. To the best of our knowledge, we report for the first time that activation of ACE2 by DIZE prevents asthma progression by altering AKT, p38, NF-κB and other inflammatory markers.

Long-lasting partnership between insulin resistance and endothelial dysfunction: role of metabolic memory.

BACKGROUND AND PURPOSE: The persistence of deleterious effects of hyperglycaemia even after glucose normalization is referred to as 'metabolic memory'. However, similar persistent effects of the metabolic consequences of a high fat diet (HFD) have not been described. EXPERIMENTAL APPROACH: Rats were given a normal pellet diet (NPD) or a HFD for 3 months. The animals from the HFD group were then returned to the NPD to observe the long-term effects of insulin resistance. Endothelial dysfunction was assessed by carbachol-mediated vasorelaxation and eNOS phosphorylation. KEY RESULTS: As expected, HFD consumption resulted in insulin resistance and endothelial dysfunction. Phosphorylation of eNOS at S1177 was decreased in HFD rats, compared with that in the NPD group. Rats on 3 months of HFD showed glucose intolerance and impaired insulin sensitivity and were then switched back to NPD (REV group) . Levels of cholesterol and triglyceride, and adiposity returned to normal in REV rats. However, endothelium-dependent vascular responses to carbachol which were impaired in HFD rats, continued to be impaired in REV rats. Similarly, decreased eNOS phosphorylation after HFD was not improved after 1 or 6 months of REV. CONCLUSIONS AND IMPLICATIONS: Our data indicate that returning to NPD did not improve the insulin sensitivity or the endothelial dysfunction induced by HFD. Although some biochemical parameters responsible for insulin resistance and endothelial dysfunction were normalized, molecular and vascular abnormalities, involving NO, persisted for several months, highlighting the long-lasting effects of metabolic memory.

Tissue specific up regulation of ACE2 in rabbit model of atherosclerosis by atorvastatin: role of epigenetic histone modifications.

Growing body of evidence points out the crucial role of ACE2 in preventing atherosclerosis. However, data on how atherosclerosis affects ACE2 expression in heart and kidney remains unknown. Atherosclerosis was induced by feeding New Zealand White rabbits with high cholesterol diet (HCD - 2%) for 12 weeks and atorvastatin was administered (5mg/kg/day p.o) in last 3 weeks. ACE2 mRNA and protein expression was assessed by Western blotting and real time PCR. HCD fed rabbits developed atherosclerosis as confirmed by increase in plasma total cholesterol, LDL and triglycerides as well as formation atherosclerotic plaques in arch of aorta. The ACE2 protein but not mRNA expression was reduced in heart and kidney of HCD rabbits. Interestingly, atorvastatin increased the ACE2 protein expression in heart and kidney of HCD rabbits. However, atorvastatin increased ACE2 mRNA in heart but not in kidney of HCD rabbits. Atorvastatin increased the occupancy of histone H3 acetylation (H3-Ac) mark on ACE2 promoter region in heart of HCD rabbits indicating direct or indirect epigenetic up-regulation of ACE2 by atorvastatin. Further, atorvastatin suppressed Ang II-induced contractile responses and enhanced AT2 receptor mediated relaxant responses in atherosclerotic aorta. We propose that atherosclerosis is associated with reduced ACE2 expression in heart and kidney. We also show an unexplored potential of atorvastatin to up-regulate ACE2 via epigenetic histone modifications. Our data suggest a novel way of replenishing ACE2 expression for preventing not only atherosclerosis but also other cardiovascular disorders.

Calorie restriction mimicking effects of roflumilast prevents diabetic nephropathy.

Little is known about role of PDE4 in the development and progression of diabetic nephropathy. Here, we investigated the effect of roflumilast, a selective PDE 4 inhibitor in type 1 diabetic nephropathy. Diabetes was induced in male Sprague-Dawley rats using streptozotocin (55 mg/kg). Diabetic rats showed elevated plasma glucose, blood urea nitrogen, creatinine and decrease in plasma albumin confirming signs of nephropathy. Roflumilast at 2 and 3mg/kg normalized these alterations. Roflumilast also suppressed oxidative stress and deposition of an extracellular matrix protein such as fibronectin and collagen in kidney of diabetic rats. TUNEL assay revealed apoptosis in diabetic kidney than control and that roflumilast prevents this effect. We show that kidney of diabetic rats displayed a state of p-AMPK and SIRT1 deficiency and that roflumilast, interestingly, was able to restore their levels. Further, roflumilast prevented an increase in HO-1 and loss in the FoxO1 expression in diabetes. However, it did not improve the reduced NRF2 levels in diabetes. This is the first report to show that, like resveratrol and other SIRT1 activators, roflumilast also mimics calorie restriction effects through activation of AMPK/SIRT1 and protects against diabetic nephropathy. This study unveils the unexplored potential of roflumilast which can be used in treatment of metabolic disorders.

Heat shock prevents insulin resistance-induced vascular complications by augmenting angiotensin-(1-7) signaling.

We have investigated the role of heat shock (HS) in preventing insulin resistance-induced endothelial dysfunction. To the best of our knowledge, we report here for the first time that insulin resistance inhibits vascular HS protein (HSP) 72 expression. HS treatment (41 °C for 20 min) restored the HSP72 expression. High-fat diet (HFD)-fed, insulin-resistant rats show attenuated angiotensin (ANG)-(1-7)-induced vasodilator effect, endothelial nitric oxide synthase (eNOS) phosphorylation, AMP-activated protein kinase phosphorylation, and sirtuin 1 (SIRT1) expression. Interestingly, HS prevented this attenuation. We also provide the first evidence that HFD-fed rats show increased vascular DNA methyltransferase 1 (DNMT1) expression and that HS prevented this increase. Our data show that in HFD-fed rats HS prevented loss in the expression of ANG-(1-7) receptor Mas and ACE2, which were responsible for vascular complications. Further, the inhibition of eNOS (l-N(G)-nitro-L-arginine methyl ester), Mas (A-779), and SIRT1 (nicotinamide) prevented the favorable effects of HS. This suggests that HS augmented ANG-(1-7) signaling via the Mas/eNOS/SIRT1 pathway. Our study, for the first time, suggests that induction of intracellular HSP72 alters DNMT1 expression, and may function as an epigenetic regulator of SIRT1 and eNOS expression. We propose that induction of HSP72 is a novel approach to prevent insulin resistance-induced vascular complications.

17-ß Oestradiol prevents cardiovascular dysfunction in post-menopausal metabolic syndrome by affecting SIRT1/AMPK/H3 acetylation.

BACKGROUND AND PURPOSE: Oestrogen therapy is known to induce cardioprotection in post-menopausal metabolic syndrome (PMS). Hence, we investigated the effect of 17-ß oestradiol (E2) on functional responses to angiotensin II and cardiovascular dysfunction in a rat model of PMS. EXPERIMENTAL APPROACH: PMS was induced in ovariectomized rats by feeding a high-fat diet for 10 weeks. Isometric tension responses of aortic rings to angiotensin II were recorded using an isometric force transducer. TUNEL assay and immunoblotting was performed to assess apoptosis and protein expression respectively in PMS. KEY RESULTS: Endothelial dysfunction in PMS was characterized by enhanced angiotensin II-induced contractile responses and impaired endothelial dependent vasodilatation. This was associated with an increased protein expression of AT1 receptors in the aorta and heart in PMS. PMS induced cardiac apoptosis by activating Bax and PARP protein expression. These changes were associated with a down-regulation in the expression of silent information regulation 2 homologue (SIRT1)/P-AMP-activated PK (AMPK) and increased H3 acetylation in aorta and heart. E2 partially suppressed angiotensin II-induced contractions, restored the protein expression of SIRT1/P-AMPK and suppressed H3 acetylation. The role of SIRT1/AMPK was further highlighted by administration of sirtinol and compound C (ex vivo), which enhanced angiotensin II contractile responses and ablated the protective effect of E2 on PMS. CONCLUSION AND IMPLICATIONS: Our results provide novel mechanisms for PMS-induced cardiovascular dysfunction involving SIRT1/AMPK/ histone H3 acetylation, which was prevented by E2. The study suggests that therapies targeting SIRT1/AMPK/epigenetic modifications may be beneficial in reducing the risk of cardiovascular disorders.

Insulin resistance induces a segmental difference in thoracic and abdominal aorta: differential expression of AT1 and AT2 receptors.

OBJECTIVES: The study was pursued to understand and compare the vascular reactivity to angiotensin II (Ang II) and its receptor expression in thoracic and abdominal aorta under insulin resistance. METHODS: Vascular reactivity to Ang II was recorded isometrically, AT1/AT2 receptor gene and protein expression was checked by RT-PCR and western blotting, respectively, and abundance of phospho (serine-10 Ph) H3 on promoter regions of Agtr1/Agtr2 genes was done by chromatin immunoprecipitation assay in aortic rings isolated from high fat diet (HFD)-fed rats. RESULTS: Our functional studies showed an increased (Emax in mg/mm: Con: 319 ±â€Š29 and HFD: 1095 ±â€Š72, P < 0.001) and unaltered (Emax in mg/mm: Con: 299 ±â€Š29 and HFD: 350 ±â€Š20, mean ±â€ŠSEM, n = 6) Ang II-induced contractile responses in thoracic and abdominal aorta of HFD rats, respectively, as compared to control rats. Interestingly, AT2R-mediated relaxation was increased in abdominal aorta (% relaxation: Con: 25 ±â€Š5.3 and HFD: 76.4 ±â€Š8.9, P < 0.001) of HFD rats but not in thoracic aorta (% relaxation: Con: 25 ±â€Š5.2 and HFD: 32 ±â€Š5.2, mean ±â€ŠSEM, n = 6). At the molecular level, increased mRNA (∼14-folds) and protein expression (∼2.5-folds) of AT2R in abdominal aorta of HFD rats was found as compared to control rats. However, AT1R mRNA and protein expression did not show any change. Chromatin immunoprecipitation with phospho H3 showed increased abundance of ser-10 phosphorylation on Agtr1 and Agtr2 gene promoter regions in thoracic and abdominal segments, respectively. But it got decreased on Agtr2 and Agtr1 genes promoter regions in thoracic and abdominal segments, respectively. CONCLUSION: We provide first evidence that insulin resistance induces segmental difference in thoracic and abdominal aorta and this may provide reason of heterogeneity for incidence of aneurysms.

Alteration in inflammatory/apoptotic pathway and histone modifications by nordihydroguaiaretic acid prevents acute pancreatitis in swiss albino mice.

Reactive oxygen radicals, pro-inflammatory mediators and cytokines have been implicated in caerulein induced acute pancreatitis. Nordihydroguaiaretic acid (NDGA), a plant lignin, has marked anti-inflammatory properties. The present study aimed to investigate the possible protective effect of NDGA against caerulein induced pancreatitis. Acute pancreatitis was induced by intraperitoneal administration of eight doses of caerulein in male swiss albino mice. NDGA was administered after 9 h of acute pancreatitis induction. Pancreatic damage and the protective effect of NDGA were assessed by oxidative stress parameters and histopathology of pancreas. The mRNA expression of heat shock proteins (DNAJ C15 and HSPD1) was examined by real-time RT-PCR analysis. Expression of HSP 27, NF-κB, TNF-α, p-p38, Bcl-2, p-PP2A, procaspase-3, caspase-3 and histone modifications were examined by western blotting. NDGA attenuated the oxidative stress, led to increased plasma α-amylase and decreased IGF-1 in AP mice. It modulated the mRNA and protein levels of heat shock proteins and reduced the expression of NF-κB, TNF-α and p-p38. It increased the number of TUNEL positive apoptotic cells in the pancreas of AP mice. In addition, NDGA prevented the changes in modifications of histone H3 in acute pancreatitis. To best of our knowledge, this is the first report which suggests that NDGA prevents the progression of acute pancreatitis by involving alteration of histone H3 modifications and modulating the expression of genes involved in inflammatory/apoptotic cascade, which may be responsible for decreased necrosis and increased apoptosis in this model of acute pancreatitis.