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Query: UMLS:C0004135 (ATM)
 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cardiac renin angiotensin system (RAS) is the target for number of therapeutic interventions which proved successful in heart failure. Angiotensin converting enzyme (ACE) inhibitors belong to the most efficient strategies available and angiotensin receptor (ATR) antagonists may be comparably effective. The direct myocardial effects of both classes of substances depend on the cardiac ANG II receptors. Both subtypes, AT1 and AT2, are expressed in the human heart. AT1 is localized on myocytes, non-myocytes, vascular smooth muscle and endothelial cells, nerve endings, and conduction tissues. AT2 has so far been found in fibrous tissue and endothelial cells. AT1 mediates myocyte hypertrophy, fibroblast proliferation, collagen synthesis, smooth muscle cell growth, endothelial adhesion molecule expression, and catecholamine synthesis. AT1 is downregulated in cardiac failure as well as in the hypertrophied transplanted heart, indicating that a 50% loss of AT1 does not impede cardiac hypertrophy. In heart failure therapy, AT1 antagonists differ from ACE inhibitors by their inhibition of the degradation of bradykinin. Bradykinin has a number intrinsic effect including vasodilation, proinflammatory actions, and modulation of fibrous tissue synthesis. In addition to bradykinin, the functional role of AT2 seems crucial for the therapeutic differences of AT1 antagonists versus ACE inhibitors.
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PMID:Myocardial angiotensin receptors in human hearts. 983 60

Hypertension and kidney damage in the double transgenic rat (dTGR) harboring both human renin and human angiotensinogen genes are dependent on the human components of the renin angiotensin system. We tested the hypothesis that monocyte infiltration and increased adhesion molecule expression are involved in the pathogenesis of kidney damage in dTGR. We also evaluated the effects of long-term angiotensin-converting enzyme (ACE) inhibition, AT1 blockade, and human renin inhibition on monocyte recruitment and inflammatory response in dTGR. Systolic blood pressure and 24-hour albuminuria were markedly increased in 7-week-old dTGR as compared with age-matched normotensive Sprague Dawley rats. We found a significant monocyte/macrophage infiltration in the renal perivascular space and increased expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in the interstitium, intima, and adventitia of the small renal vessels. alphaLbeta2 integrin and alpha4beta1 integrin, the corresponding ligands for ICAM-1 and VCAM-1, were also found on infiltrating monocytes/macrophages. The expression of plasminogen activator inhibitor-1 and fibronectin in the kidneys of dTGR were increased and distributed similarly to ICAM-1. In 4-week-old dTGR, long-term treatment with ACE inhibition (cilazapril), AT1 receptor blockade (valsartan), and human renin inhibition (RO 65-7219) (each drug 10 mg/kg by gavage once a day for 3 weeks) completely prevented the development of albuminuria. However, only cilazapril and valsartan were able to decrease blood pressure to normotensive levels. Interestingly, the drugs were all equally effective in preventing monocyte/macrophage infiltration and the overexpression of adhesion molecules, plasminogen activator inhibitor-1, and fibronectin in the kidney. Our findings indicate that angiotensin II causes monocyte recruitment and vascular inflammatory response in the kidney by blood pressure-dependent and blood pressure-independent mechanisms. ACE inhibition, AT1 receptor blockade, and human renin inhibition all prevent monocyte/macrophage infiltration and increased adhesion molecule expression in the kidneys of dTGR.
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PMID:Monocyte infiltration and adhesion molecules in a rat model of high human renin hypertension. 993 Nov 35

There is recent evidence that angiotensin-converting enzyme (ACE) inhibition reduces postischemic injury and angiotensin II receptor inhibition may have similar effects. We therefore further characterized the role of ACE- vs. AT1-receptor inhibition on cell injury and temporal association of leukocyte endothelial interaction in response to ischemia-reperfusion. A combined in vivo and in vitro study comparing the ACE inhibitor enalapril and the AT1-receptor antagonist losartan was performed. The extent and temporal correlation of cellular damage (propidium-iodide staining), microvascular perfusion failure and leukocyte-endothelial interaction (leukocyte adherence) were investigated by means of intravital microscopy, after the application of hemodynamically ineffective doses of enalapril and losartan (5 mg/kg). A hamster dorsal skinfold model with a 4-h tourniquet ischemia was used. In vitro, the effect of enalapril and losartan on polymorphonuclear cell (PMN) adherence, as well as adhesion molecule expression (ICAM-1, VCAM-1), on hypoxia- or IL-1beta-stimulated endothelial cells (HUVEC) was assessed using a PMN-adhesion assay and flow cytometry, respectively. Ischemia-reperfusion responses revealed a biphasic pattern, comprised of an early phase (30 min) of acute cellular damage and microvascular perfusion failure, followed by a late increase (240 min) in leukocyte adherence in vivo. Enalapril significantly reduced early cellular damage, microvascular perfusion failure, and leukocyte adherence in response to ischemia-reperfusion. Conversely, AT1 receptor inhibition with losartan proved to be ineffective at attenuating postischemic microcirculatory disorders (leukocyte-endothelial interactions, microvascular perfusion failure) and aggravated cellular injury. In vitro, enalapril reduced PMN adherence and ICAM-1 and VCAM-1 expression, while losartan was ineffective in the same respect. Following ischemia-reperfusion injury, ACE- versus AT1-receptor inhibition induce differential effects concerning the extent and temporal association of cell injury and leukocyte-endothelial interaction. The use of enalapril combines the beneficial effects of preventing cell and vascular injury immediately after reperfusion, with a delayed inhibition of the inflammatory response. Since the AT1-receptor inhibitor losartan did not mimic effects obtained with ACE inhibition, it is conceivable that the responses in ischemia-reperfusion are mediated by a non-angiotensin II-AT1 receptor-dependent mechanism.
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PMID:Differential effects of short-term ace- and AT1-receptor inhibition on postischemic injury and leukocyte adherence in vivo and in vitro. 1071 75

Angiotensin (Ang) II is capable of producing inflammatory changes by signals through its AT1 receptor. Reactive oxygen species production, adhesion molecule expression, chemokines, and other mediators are involved. Nuclear factor-kappaB (NK-kappaB) and activator protein 1 (AP-1) are two of the transcription factors activating the responsible genes. We have studied Ang II-independent modulating effects in a double transgenic rat model harboring the human renin and angiotensinogen genes. We have recently focused on the protective effects of HMG-CoA reductase inhibition and review these data here. We found that cerivastatin decreased mortality, lowered blood pressure, preserved renal function, decreased cardiac hypertrophy, and inhibited the entire chain of inflammatory events. Furthermore, NF-kappaB and AP-1 activation was sharply attenuated. We also observed that cerivastatin blocked ERK1/2 phosphorylation in vivo and in vitro. Cerivastatin also inhibited phorbol ester-transmitted events in vascular smooth muscle cells. Because Rho, a member of the Ras protein superfamily is important to Ang II-dependent and -independent vascular smooth muscle signaling events, we suggest that cerivastatin may act by inhibiting the prenylation, membrane anchoring, and subsequent activation of Ras proteins. These data may in part explain cholesterol-independent, HMG-CoA reductase-related, protective effects.
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PMID:Modulating angiotensin II-induced inflammation by HMG Co-A reductase inhibition. 1141 66

Hypercholesterolemia elicits an inflammatory response in the microvasculature that is accompanied by an increased expression of angiotensin II type-1 receptors (AT1-R) on platelets, leukocytes, and endothelial cells. AT1-R blockade attenuates inflammatory responses to angiotensin II (eg, adhesion molecule expression and reactive oxygen species production). We investigated whether AT1-R antagonism attenuates the platelet and leukocyte recruitment induced by acute hypercholesterolemia in postcapillary venules. Leukocyte and platelet adhesion and oxidative stress were quantified by intravital microscopy in cremaster muscle, and P-selectin and AT1-R expression was determined in mice placed on a normal diet (ND) or high-cholesterol diet (HCD) for 2 weeks. Platelet and leukocyte adhesion was significantly elevated by hypercholesterolemia. In HCD mice receiving losartan (HCD-Los) in drinking water, platelet and leukocyte recruitment was reduced to ND levels. Increased platelet adhesion was observed in HCD mice receiving platelets from HCD-Los mice, consistent with a direct beneficial action of losartan on the vessel wall. Hypercholesterolemia elicited an oxidative stress in venules and an increased expression of P-selectin and AT1-R. The oxidative stress and AT1-R upregulation were reduced by losartan, but the P-selectin response was not. We propose that AT1-R engagement contributes to the prothrombogenic and proinflammatory state induced in venules by hypercholesterolemia.
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PMID:Angiotensin II type-1 receptor antagonism attenuates the inflammatory and thrombogenic responses to hypercholesterolemia in venules. 1565 21

Lifestyle-related diseases cause macro-and microangiopathies in the major organs including the brain, heart, kidney, and eye, and as a result, shorten the lifespan. The renin-angiotensin system (RAS) has recently been shown to contribute to the processes of accelerated aging caused by lifestyle-related diseases from visceral obesity in the early stage to late-onset organ damage. Vision-threatening diabetic retinopathy and age-related macular degeneration (AMD), associated with lifestyle-related diseases as risk factors for progression, develop retinal and choroidal neovascularization (CNV), respectively, in their advanced stages. We have found that tissue RAS is activated in the pathogenesis of diabetic retinopathy and CNV, leading to angiotensin type 1 receptor(AT1-R)-mediated expression of inflammation-related molecules including vascular endothelial growth factor (VEGF), intercellular adhesion molecule (ICAM)-1, and monocyte chemotactic protein(MCP)-1. Neuronal dysfunction in diabetic retinopathy is also shown to result from AT1-R-mediated degradation of synaptic proteins. Moreover, we revealed for the first time that the receptor for prorenin [(pro) renin receptor] is expressed in the eye, although prorenin was until recently believed to be just an inactive precursor of renin. Prorenin binds to the receptor that causes dual activation of its intracellular signaling and tissue RAS, and this pathogenic mechanism is termed receptor-associated prorenin system (RAPS)'. We have demonstrated the contribution of RAPS to the pathogenesis of CNV and dual regulation of VEGF and MCP-1 by signal transduction via (pro) renin receptor and AT1-R. Next, we report the potential validity of food factor supplements as a therapeutic strategy for preventing the retinal and choroidal pathologies driven by RAS-induced inflammatory and angiogenic molecules. Functional food factors examined include lutein in yellow-green vegetables, the omega-3 polyunsaturated fatty acid eicosapentaenoic acid purified from fish oil, and red pigment astaxanthin from salmon and shrimp. We recently revealed that these food factors prevent intraocular angiogenesis and inflammation by inhibiting the expression of inflammatory molecules including VEGF, ICAM-1, and MCP-1. Preventive medicine for AMD and diabetic retinopathy, both of which have lifestyle-related diseases as a systemic background, has attracted growing attention. In the present review, we provide biological evidence for RAS inhibition and food factor supplementation in the early intervention for retinal and choroidal pathologies as an 'anti-aging ophthalmology' approach.
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PMID:[Lifestyle-related diseases and anti-aging ophthalmology: suppression of retinal and choroidal pathologies by inhibiting renin-angiotensin system and inflammation]. 1934 85

Receptor-associated prorenin system (RAPS) refers to the pathogenic mechanisms whereby prorenin binding to (pro)renin receptor [(P)RR] dually activates tissue renin-angiotensin system (RAS) and RAS-independent intracellular signaling through the receptor. Although we found significant involvement of angiotensin II type 1 receptor (AT1-R) in intraocular inflammation and neovascularization, central pathologies of age-related macular degeneration and diabetic retinopathy, the association of RAPS with these vision-threatening disorders has not been defined. (P)RR blockade to murine disease models led to significant suppression of laser-induced choroidal neovascularization and diabetes-induced retinal inflammation together with the upregulation of intercellular adhesion molecule (ICAM)-1, monocyte chemotactic protein (MCP)-1 and vascular endothelial growth factor (VEGF). Either the genetic ablation or the pharmacological blockade of AT1-R exhibited significant reduction of choroidal and retinal abnormalities, both of which were further suppressed by (P)RR blockade. (P)RR blockade inhibited ERK activation and the production of VEGF and MCP-1, but not ICAM-1, in AT1-R-deficient mice with retinal and choroidal disorders. These recent findings indicate significant contribution of RAPS to the pathogenesis of age-related macular degeneration and diabetic retinopathy.
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PMID:Receptor-associated prorenin system in the pathogenesis of retinal diseases. 2265 85

Angiotensin II (Ang II) plays an important role in the regulation of the T-cell response during inflammation. However, the cellular mechanisms underlying the regulation of lymphocytes under physiologic conditions have not yet been studied. Here, we tested the influence of Ang II on T-cell migration using T cells from BALB/c mice. The results obtained in vivo showed that when Ang II production or the AT1 receptor were blocked, T-cell counts were enhanced in blood but decreased in the spleen. The significance of these effects was confirmed by observing that these cells migrate, through fibronectin to Ang II via the AT1 receptor. We also observed a gradient of Ang II from peripheral blood to the spleen, which explains its chemotactic effect on this organ. The following cellular mechanisms were identified to mediate the Ang II effect: upregulation of the chemokine receptor CCR9; upregulation of the adhesion molecule CD62L; increased production of the chemokines CCL19 and CCL25 in the spleen. These results indicate that the higher levels of Ang II in the spleen and AT1 receptor activation contribute to migration of naive T cells to the spleen, which expands our understanding on how the Ang II/AT1 receptor axis contributes to adaptive immunity.
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PMID:Renin-angiotensin system contributes to naive T-cell migration in vivo. 2575 53