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O'Callaghan EL, Choong YT, Jancovski N, Allen AM. Central angiotensinergic mechanisms associated with hypertension. Auton Neurosci 2013; 175:85-92. [PMID: 23466041 DOI: 10.1016/j.autneu.2013.01.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 01/23/2013] [Accepted: 01/23/2013] [Indexed: 12/20/2022]
Abstract
Following its generation by both systemic and tissue-based renin-angiotensin systems, angiotensin II interacts with specific, G-protein coupled receptors to modulate multiple physiological systems, including the cardiovascular system. Genetic models in which the different components of the renin-angiotensin system have been deleted show large changes in resting blood pressure. Interruption of the generation of angiotensin II, or its interaction with these receptors, decreases blood pressure in hypertensive humans and experimental animal models of hypertension. Whilst the interaction of angiotensin II with the kidney is pivotal in this modulation of blood pressure, an involvement of the system in other tissues is important. Both systemic angiotensins, acting via the blood-brain barrier deficient circumventricular organs, and centrally-generated angiotensin modulate cardiovascular control by regulating fluid and electrolyte ingestion, autonomic activity and neuroendocrine function. This review discusses the pathways in the brain that are involved in this regulation of blood pressure as well as examining the sites in which altered angiotensin function might contribute to the development and maintenance of high blood pressure.
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Affiliation(s)
- Erin L O'Callaghan
- Department of Physiology, University of Melbourne, Vic., 3010, Australia
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202
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Heijnen BFJ, Nelissen J, van Essen H, Fazzi GE, Cohen Tervaert JW, Peutz-Kootstra CJ, Mullins JJ, Schalkwijk CG, Janssen BJA, Struijker-Boudier HAJ. Irreversible renal damage after transient renin-angiotensin system stimulation: involvement of an AT1-receptor mediated immune response. PLoS One 2013; 8:e57815. [PMID: 23469072 PMCID: PMC3585138 DOI: 10.1371/journal.pone.0057815] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 01/26/2013] [Indexed: 01/10/2023] Open
Abstract
Transient activation of the renin-angiotensin system (RAS) induces irreversible renal damage causing sustained elevation in blood pressure (BP) in Cyp1a1-Ren2 transgenic rats. In our current study we hypothesized that activation of the AT1-receptor (AT1R) leads to a T-cell response causing irreversible impairment of renal function and hypertension. Cyp1a1-Ren2 rats harbor a construct for activation of the RAS by indole-3-carbinol (I3C). Rats were fed a I3C diet between 4–8 weeks of age to induce hypertension. Next, I3C was withdrawn and rats were followed-up for another 12 weeks. Additional groups received losartan (20 mg/kg/day) or hydralazine (100 mg/kg/day) treatment between 4–8 weeks. Rats were placed for 24h in metabolic cages before determining BP at week 8, 12 and 20. At these ages, subsets of animals were sacrificed and the presence of kidney T-cell subpopulations was investigated by immunohistochemistry and molecular marker analysis. The development of sustained hypertension was completely prevented by losartan, whereas hydralazine only caused a partial decrease in BP. Markers of renal damage: KIM-1 and osteopontin were highly expressed in urine and kidney samples of I3C-treated rats, even until 20 weeks of age. Additionally, renal expression of regulatory-T cells (Tregs) was highly increased in I3C-treated rats, whereas the expression of T-helper 1 (Th1) cells demonstrated a strong decrease. Losartan prevented these effects completely, whereas hydralazine was unable to affect these changes. In young Cyp1a1-Ren2 rats AT1R activation leads to induction of an immune response, causing a shift from Th1-cells to Tregs, contributing to the development of irreversible renal damage and hypertension.
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Affiliation(s)
- Bart F J Heijnen
- Department of Pharmacology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.
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203
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Neuroimmune communication in hypertension and obesity: a new therapeutic angle? Pharmacol Ther 2013; 138:428-40. [PMID: 23458610 DOI: 10.1016/j.pharmthera.2013.02.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 02/12/2013] [Indexed: 12/13/2022]
Abstract
Hypertension is an epidemic health concern and a major risk factor for the development of cardiovascular disease. Although there are available treatment strategies for hypertension, numerous hypertensive patients do not have their clinical symptoms under control and it is imperative that new avenues to treat or prevent high blood pressure in these patients are developed. It is well established that increases in sympathetic nervous system (SNS) outflow and enhanced renin-angiotensin system (RAS) activity are common features of hypertension and various pathological conditions that predispose individuals to hypertension. More recently, hypertension has also become recognized as an immune condition and accumulating evidence suggests that interactions between the RAS, SNS and immune systems play a role in blood pressure regulation. This review summarizes what is known about the interconnections between the RAS, SNS and immune systems in the neural regulation of blood pressure. Based on the reviewed studies, a model for RAS/neuroimmune interactions during hypertension is proposed and the therapeutic potential of targeting RAS/neuroimmune interactions in hypertensive patients is discussed. Special emphasis is placed on the applicability of the proposed model to obesity-related hypertension.
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204
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McBryde FD, Abdala AP, Hendy EB, Pijacka W, Marvar P, Moraes DJA, Sobotka PA, Paton JFR. The carotid body as a putative therapeutic target for the treatment of neurogenic hypertension. Nat Commun 2013; 4:2395. [PMID: 24002774 DOI: 10.1038/ncomms3395] [Citation(s) in RCA: 179] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 08/02/2013] [Indexed: 01/19/2023] Open
Abstract
In the spontaneously hypertensive (SH) rat, hyperoxic inactivation of the carotid body (CB) produces a rapid and pronounced fall in both arterial pressure and renal sympathetic nerve activity (RSA). Here we show that CB de-afferentation through carotid sinus nerve denervation (CSD) reduces the overactive sympathetic activity in SH rats, providing an effective antihypertensive treatment. We demonstrate that CSD lowers RSA chronically and that this is accompanied by a depressor response in SH but not normotensive rats. The drop in blood pressure is not dependent on renal nerve integrity but mechanistically accompanied by a resetting of the RSA-baroreflex function curve, sensitization of the cardiac baroreflex, changes in renal excretory function and reduced T-lymphocyte infiltration. We further show that combined with renal denervation, CSD remains effective, producing a summative response indicative of an independent mechanism. Our findings indicate that CB de-afferentation is an effective means for robust and sustained sympathoinhibition, which could translate to patients with neurogenic hypertension.
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Affiliation(s)
- Fiona D McBryde
- School of Physiology and Pharmacology, Bristol Heart Institute, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, England
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205
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Nguyen H, Chiasson VL, Chatterjee P, Kopriva SE, Young KJ, Mitchell BM. Interleukin-17 causes Rho-kinase-mediated endothelial dysfunction and hypertension. Cardiovasc Res 2012; 97:696-704. [PMID: 23263331 DOI: 10.1093/cvr/cvs422] [Citation(s) in RCA: 194] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
AIMS Elevated levels of pro-inflammatory cytokine interleukin-17A (IL-17) are associated with hypertensive autoimmune diseases; however, the connection between IL-17 and hypertension is unknown. We hypothesized that IL-17 increases blood pressure by decreasing endothelial nitric oxide production. METHODS AND RESULTS Acute treatment of endothelial cells with IL-17 caused a significant increase in phosphorylation of the inhibitory endothelial nitric oxide (NO) synthase residue threonine 495 (eNOS Thr495). Of the kinases known to phosphorylate eNOS Thr495, only inhibition of Rho-kinase prevented the IL-17-induced increase. IL-17 caused a threefold increase in the Rho-kinase activator RhoA, and this was prevented by an IL-17 neutralizing antibody. In isolated mouse aortas, IL-17 significantly increased eNOS Thr495 phosphorylation, induced RhoA expression, and decreased NO-dependent relaxation responses, all of which were prevented by either an IL-17 neutralizing antibody or inhibition of Rho-kinase. In mice, IL-17 treatment for 1 week significantly increased systolic blood pressure and this was associated with decreased aortic NO-dependent relaxation responses, increased eNOS Thr495 phosphorylation, and increased RhoA expression. Inhibition of Rho-kinase prevented the hypertension caused by IL-17. CONCLUSION These data demonstrate that IL-17 activates RhoA/Rho-kinase leading to endothelial dysfunction and hypertension. Inhibitors of IL-17 or Rho-kinase may prove useful as anti-hypertensive drugs in IL-17-associated autoimmune diseases.
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Affiliation(s)
- Hoanglan Nguyen
- Division of Nephrology & Hypertension, Department of Internal Medicine, Texas A&M Health Science Center College of Medicine/Scott & White Memorial Hospital, 702 SW HK Dodgen Loop, Temple, TX 76504, USA
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206
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Lob HE, Schultz D, Marvar PJ, Davisson RL, Harrison DG. Role of the NADPH oxidases in the subfornical organ in angiotensin II-induced hypertension. Hypertension 2012; 61:382-7. [PMID: 23248154 DOI: 10.1161/hypertensionaha.111.00546] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Reactive oxygen species and the NADPH oxidases contribute to hypertension via mechanisms that remain undefined. Reactive oxygen species produced in the central nervous system have been proposed to promote sympathetic outflow, inflammation, and hypertension, but the contribution of the NADPH oxidases to these processes in chronic hypertension is uncertain. We therefore sought to identify how NADPH oxidases in the subfornical organ (SFO) of the brain regulate blood pressure and vascular inflammation during sustained hypertension. We produced mice with loxP sites flanking the coding region of the NADPH oxidase docking subunit p22(phox). SFO-targeted injections of an adenovirus encoding cre-recombinase markedly diminished p22(phox), Nox2, and Nox4 mRNA in the SFO, as compared with a control adenovirus encoding red-fluorescent protein injection. Increased superoxide production in the SFO by chronic angiotensin II infusion (490 ng/kg min(-1) × 2 weeks) was blunted in adenovirus encoding cre-recombinase-treated mice, as detected by dihydroethidium fluorescence. Deletion of p22(phox) in the SFO eliminated the hypertensive response observed at 2 weeks of angiotensin II infusion compared with control adenovirus encoding red-fluorescent protein-treated mice (mean arterial pressures=97 ± 15 versus 154 ± 6 mm Hg, respectively; P=0.0001). Angiotensin II infusion also promoted marked vascular inflammation, as characterized by accumulation of activated T-cells and other leukocytes, and this was prevented by deletion of the SFO p22(phox). These experiments definitively identify the NADPH oxidases in the SFO as a critical determinant of the blood pressure and vascular inflammatory responses to chronic angiotensin II, and further support a role of reactive oxygen species in central nervous system signaling in hypertension.
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Affiliation(s)
- Heinrich E Lob
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, USA
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207
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Waki H, Hendy EB, Hindmarch CCT, Gouraud S, Toward M, Kasparov S, Murphy D, Paton JFR. Excessive leukotriene B4 in nucleus tractus solitarii is prohypertensive in spontaneously hypertensive rats. Hypertension 2012; 61:194-201. [PMID: 23172924 DOI: 10.1161/hypertensionaha.112.192252] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Inflammation within the brain stem microvasculature has been associated with chronic cardiovascular diseases. We found that the expression of several enzymes involved in arachidonic acid-leukotriene B4 (LTB4) production was altered in nucleus tractus solitarii (NTS) of spontaneously hypertensive rat (SHR). LTB4 produced from arachidonic acid by 5-lipoxygenase is a potent chemoattractant of leukocytes. Leukotriene B4-12-hydroxydehydrogenase (LTB4-12-HD), which degrades LTB4, was downregulated in SHR rats compared with that in Wistar-Kyoto rats. Quantitative real-time PCR revealed that LTB4-12-HD was reduced by 63% and 58% in the NTS of adult SHR and prehypertensive SHR, respectively, compared with that in age-matched Wistar-Kyoto rats (n=6). 5-lipoxygenase gene expression was upregulated in the NTS of SHR (≈50%; n=6). LTB4 levels were increased in the NTS of the SHR, (17%; n=10, P<0.05). LTB4 receptors BLT1 (but not BLT2) were expressed on astroglia in the NTS but not neurons or vessels. Microinjection of LTB4 into the NTS of Wistar-Kyoto rats increased both leukocyte adherence and arterial pressure for over 4 days (peak: +15 mm Hg; P<0.01). In contrast, blockade of NTS BLT1 receptors lowered blood pressure in the SHR (peak: -13 mm Hg; P<0.05) but not in Wistar-Kyoto rats. Thus, excessive amounts of LTB4 in NTS of SHR, possibly as a result of upregulation of 5-lipoxygenase and downregulation of LTB4-12-HD, can induce inflammation. Because blockade of NTS BLT1 receptors lowered arterial pressure in the SHR, their endogenous activity may contribute to the hypertensive state of this rodent model. Thus, inflammatory reactions in the brain stem are causally associated with neurogenic hypertension.
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Affiliation(s)
- Hidefumi Waki
- School of Physiology and Pharmacology, Bristol Heart Institute, Medical Sciences Building, University of Bristol, Bristol, United Kingdom
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208
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Williams R. Circulation Research
“In This Issue” Anthology. Circ Res 2012. [DOI: 10.1161/res.0b013e31826f7938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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209
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210
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Pons H, Ferrebuz A, Quiroz Y, Romero-Vasquez F, Parra G, Johnson RJ, Rodriguez-Iturbe B. Immune reactivity to heat shock protein 70 expressed in the kidney is cause of salt-sensitive hypertension. Am J Physiol Renal Physiol 2012; 304:F289-99. [PMID: 23097471 DOI: 10.1152/ajprenal.00517.2012] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Hypertension affects one-third of the adult population of the world. The causes of hypertension are incompletely understood, but relative impairment of sodium excretion is central to its pathogenesis. Immune cell infiltration in the kidney is a constant finding in hypertension that in association with local angiotensin and oxidants causes a defect in sodium excretion. However, it is unclear if the T cell influx into the kidney responds to nonspecific chemokine cues or is due to antigen-driven immune attraction. We found that T cells in experimentally induced salt-driven hypertension present a CD4 clonal response to heat shock protein 70 (HSP70) that is overexpressed in the kidney. We used a highly preserved amino acid sequence within the HSP molecule to induce immune tolerance associated with the generation of IL-10 producing regulatory T cells. Immune tolerant rats to HSP70 developed minimal renal inflammation and were protected from the development of salt-sensitive hypertension. Adoptive transfer of T lymphocytes isolated from spleen of tolerized rats also reversed hypertension. HSP70 gene delivery to the renal vein of the kidneys of rats sensitized to HSP70 caused an increment in blood pressure in response to a high-salt diet. The HSP70 peptide used in this work induces a strong proliferative response in peripheral blood lymphocytes of patients with essential hypertension. These studies provide evidence that autoimmunity plays a role in salt-sensitive hypertension and identifies HSP70 expressed in the kidney as one key antigen. These findings raise the possibility of novel approaches to the treatment of this condition.
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Affiliation(s)
- Héctor Pons
- Hospital Universitario y Universidad del Zulia, Maracaibo, Venezuela
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211
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Cates MJ, Dickinson CJ, Hart ECJ, Paton JFR. Neurogenic hypertension and elevated vertebrobasilar arterial resistance: is there a causative link? Curr Hypertens Rep 2012; 14:261-9. [PMID: 22562144 DOI: 10.1007/s11906-012-0267-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
There is evidence of sympathetic overdrive in a significant proportion of patients with essential hypertension and an animal model of the condition, the spontaneously hypertensive rat (SHR). The reasons for this remain elusive. However, there is also evidence of narrowing of the arteries supplying the brainstem in the SHR and hypertensive humans. In this review, we discuss the possible role of brainstem hypoperfusion in driving increased sympathetic activity and hypertension.
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212
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Jun JY, Zubcevic J, Qi Y, Afzal A, Carvajal JM, Thinschmidt JS, Grant MB, Mocco J, Raizada MK. Brain-mediated dysregulation of the bone marrow activity in angiotensin II-induced hypertension. Hypertension 2012; 60:1316-23. [PMID: 23045460 DOI: 10.1161/hypertensionaha.112.199547] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Oxidative stress in the brain is implicated in increased sympathetic drive, inflammatory status, and vascular dysfunctions, associated with development and establishment of hypertension. However, little is known about the mechanism of this impaired brain-vascular communication. Here, we tested the hypothesis that increased oxidative stress in the brain cardioregulatory areas, such as the paraventricular nucleus of the hypothalamus, is driven by mitochondrial reactive oxygen species and leads to increased inflammatory cells (ICs) and decreased/dysfunctional endothelial progenitor cells (EPCs), thereby compromising vasculature repair and accelerating hypertension. Chronic angiotensin II infusion resulted in elevated blood pressure and sympathetic vasomotor drive, decreased spontaneous baroreflex gain, and increased microglia activation in the paraventricular nucleus. This was associated with 46% decrease in bone marrow (BM)-derived EPCs and 250% increase in BM ICs, resulting in 5-fold decrease of EPC/IC ratio in the BM. Treatment with mitochondrial-targeted antioxidant, a scavenger of mitochondrial O(2)(-·), intracerebroventricularly but not subcutaneously attenuated angiotensin II-induced hypertension, decreased activation of microglia in the paraventricular nucleus, and normalized EPCs/ICs. This functional communication between the brain and BM was confirmed by retrograde neuronal labeling from the BM with green fluorescent protein-tagged pseudorabies virus. Administration of green fluorescent protein-tagged pseudorabies virus into the BM resulted in predominant labeling of paraventricular nucleus neurons within 3 days, with some fluorescence in the nucleus tractus solitarius, the rostral ventrolateral medulla, and subfornical organ. Taken together, these data demonstrate that inhibition of mitochondrial reactive oxygen species attenuates angiotensin II-induced hypertension and corrects the imbalance in EPCs/ICs in the BM. They suggest that an imbalance in vascular reparative and ICs may perpetuate vascular pathophysiology in this model of hypertension.
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Affiliation(s)
- Joo Yun Jun
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL 32610, USA
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213
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Alghamri MS, Weir NM, Anstadt MP, Elased KM, Gurley SB, Morris M. Enhanced angiotensin II-induced cardiac and aortic remodeling in ACE2 knockout mice. J Cardiovasc Pharmacol Ther 2012; 18:138-51. [PMID: 23043153 DOI: 10.1177/1074248412460124] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Angiotensin-converting enzyme 2 (ACE2) is present in the heart and thought to exert protective functions. We conducted studies in ACE2 deficient mice to determine whether enzyme loss would exacerbate the cardiac and vascular pathological responses to chronic subcutaneous (sc) angiotensin II (Ang II) infusion. Eight-week-old male ACE2 knockout (KO) and wild type (WT) mice were infused with Ang II (1000 ng/kg per min, 4 weeks) using mini-osmotic pumps. Blood pressure (radiotelemetry), cardiac function (echocardiography, echo), cardiac/aortic structure (histology, collagen, and oxidative stress), and vascular inflammation were examined. Before Ang II infusion, ACE2 KO mice showed unaltered cardiac function and blood pressure. After 4 weeks of Ang II infusion, the mean arterial pressure (MAP) increased from 96 ± 2 to 136 ± 17 mm Hg (∼40%) in WT and from 104 ± 5 to 141 ± 13 mm Hg (∼ 35%) in ACE2 KO. While there were no differences in MAP between groups, the ACE2 KO responded differently to the hypertensive stimulus. Echo analysis revealed severe myocardial dysfunction in Ang II-infused ACE2 KO (Ang ACE2 KO). Ejection fraction was lower (39% versus 50%) as was fractional shortening (27% versus 38%) in ACE2 KO versus WT, respectively. Cardiac dysfunction was associated with hypertrophic cardiomyopathy shown by increased left-ventricular wall thickness, average cardiomyocyte cross-sectional area, and heart weight/body weight ratio. Collagen staining in the myocardium and aorta revealed increased collagen in Ang ACE2 KO, suggestive of remodeling. Results also showed enhanced oxidative stress in the myocardium and aorta of Ang ACE2 KO. There was a 3-fold elevation in macrophage inflammatory protein 1α (MIP 1α) in the aorta of ACE2 KO. Studies in the ACE2 KO model reveal the importance of ACE2 in the maladaptive cardiac and aortic responses to Ang II stimulation, seen as enhanced remodeling using physiological, structural, and biochemical markers. Results document a cardio- and vascular-protective role of ACE2 under pathological conditions.
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Affiliation(s)
- Mahmoud S Alghamri
- Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, OH, USA
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214
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Wu KLH, Chan SHH, Chan JYH. Neuroinflammation and oxidative stress in rostral ventrolateral medulla contribute to neurogenic hypertension induced by systemic inflammation. J Neuroinflammation 2012; 9:212. [PMID: 22958438 PMCID: PMC3462714 DOI: 10.1186/1742-2094-9-212] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Accepted: 08/27/2012] [Indexed: 02/07/2023] Open
Abstract
Background In addition to systemic inflammation, neuroinflammation in the brain, which enhances sympathetic drive, plays a significant role in cardiovascular diseases, including hypertension. Oxidative stress in rostral ventrolateral medulla (RVLM) that augments sympathetic outflow to blood vessels is involved in neural mechanism of hypertension. We investigated whether neuroinflammation and oxidative stress in RVLM contribute to hypertension following chronic systemic inflammation. Methods In normotensive Sprague-Dawley rats, systemic inflammation was induced by infusion of Escherichia coli lipopolysaccharide (LPS) into the peritoneal cavity via an osmotic minipump. Systemic arterial pressure and heart rate were measured under conscious conditions by the non-invasive tail-cuff method. The level of the inflammatory markers in plasma or RVLM was analyzed by ELISA. Protein expression was evaluated by Western blot or immunohistochemistry. Tissue level of superoxide anion (O2·-) in RVLM was determined using the oxidation-sensitive fluorescent probe dihydroethidium. Pharmacological agents were delivered either via infusion into the cisterna magna with an osmotic minipump or microinjection bilaterally into RVLM. Results Intraperitoneal infusion of LPS (1.2 mg/kg/day) for 14 days promoted sustained hypertension and induced a significant increase in plasma level of C-reactive protein, tumor necrosis factor-α (TNF-α), or interleukin-1β (IL-1β). This LPS-induced systemic inflammation was accompanied by activation of microglia, augmentation of IL-1β, IL-6, or TNF-α protein expression, and O2·- production in RVLM, all of which were blunted by intracisternal infusion of a cycloxygenase-2 (COX-2) inhibitor, NS398; an inhibitor of microglial activation, minocycline; or a cytokine synthesis inhibitor, pentoxifylline. Neuroinflammation in RVLM was also associated with a COX-2-dependent downregulation of endothelial nitric oxide synthase and an upregulation of intercellular adhesion molecule-1. Finally, the LPS-promoted long-term pressor response and the reduction in expression of voltage-gated potassium channel, Kv4.3 in RVLM were antagonized by minocycline, NS398, pentoxifylline, or a superoxide dismutase mimetic, tempol, either infused into cisterna magna or microinjected bilaterally into RVLM. The same treatments, on the other hand, were ineffective against LPS-induced systemic inflammation. Conclusion These results suggest that systemic inflammation activates microglia in RVLM to induce COX-2-dependent neuroinflammation that leads to an increase in O2·- production. The resultant oxidative stress in RVLM in turn mediates neurogenic hypertension.
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Affiliation(s)
- Kay L H Wu
- Center for Translational Research in Biomedical Sciences, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Kaohsiung, 83301, Taiwan
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215
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Sagan A, Mrowiecki W, Mikolajczyk TP, Urbanski K, Siedlinski M, Nosalski R, Korbut R, Guzik TJ. Local inflammation is associated with aortic thrombus formation in abdominal aortic aneurysms. Relationship to clinical risk factors. Thromb Haemost 2012; 108:812-23. [PMID: 22955940 DOI: 10.1160/th12-05-0339] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 07/26/2012] [Indexed: 01/11/2023]
Abstract
Intraluminal thrombus formation in aortic abdominal aneurysms (AAA) is associated with adverse clinical prognosis. Interplay between coagulation and inflammation, characterised by leukocyte infiltration and cytokine production, has been implicated in AAA thrombus formation. We studied leukocyte (CD45+) content by flow cytometry in AAA thrombi from 27 patients undergoing surgical repair. Luminal parts of thrombi were leukocyte-rich, while abluminal segments showed low leukocyte content. CD66b+ granulocytes were the most prevalent, but their content was similar to blood. Monocytes (CD14+) and T cells (CD3+) were also abundant, while content of B lymphocytes (CD19+) and NK cells (CD56+CD16+) were low. Thrombi showed comparable content of CD14highCD16- monocytes and lower CD14highCD16+ and CD14dimCD16+, than blood. Monocytes were activated with high CD11b, CD11c and HLA-DR expression. Total T cell content was decreased in AAA thrombus compared to peripheral blood but CD8 and CD3+CD4-CD8- (double negative T cell) contents were increased in thrombi. CD4+ cells were lower but highly activated (high CD69, CD25 and HLA-DR). No differences in T regulatory (CD4+CD25+FoxP3+) cell or pro-atherogenic CD4+CD28null lymphocyte content were observed between thrombi and blood. Thrombus T cells expressed high levels of CCR5 receptor for chemokine RANTES, commonly released from activated platelets. Leukocyte or T cell content in thrombi was not correlated with aneurysm size. However, CD3+ content was significantly associated with smoking in multivariate analysis taking into account major risk factors for atherosclerosis. In conclusion, intraluminal AAA thrombi are highly inflamed, predominantly with granulocytes, CD14highCD16- monocytes and activated T lymphocytes. Smoking is associated with T cell infiltration in AAA intraluminal thrombi.
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Affiliation(s)
- Agnieszka Sagan
- Translational Medicine Laboratory, Department of Internal and Agricultural Medicine, Jagiellonian University School of Medicine, J Dietl Hospital, Ul Skarbowa 1, 31-121 Cracow, Poland
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216
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Marvar PJ, Harrison DG. Stress-dependent hypertension and the role of T lymphocytes. Exp Physiol 2012; 97:1161-7. [PMID: 22941978 DOI: 10.1113/expphysiol.2011.061507] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Hypertension is a significant global health burden that is associated with an increased risk of stroke, atherosclerosis and other cardiovascular diseases. Several risk factors, including high dietary salt, obesity, genetics and race, as well as behavioural and psychological factors, contribute to development of this complex disease. Various hypertensive stimuli enhance sympathetic drive and promote autonomic dysfunction leading to elevated blood pressure. As our understanding of the pathogenesis and end-organ damage associated with hypertension increases, mounting evidence also highlights the role of inflammation in this process and, in particular, the role of the adaptive immune system and T cells. This review discusses recent findings regarding the role of the central nervous system, T lymphocytes and the impact of cardiovascular risk factors, such as psychological stress, in hypertension.
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Affiliation(s)
- Paul J Marvar
- Department of Psychiatry, Emory University School of Medicine, Atlanta, GA, USA.
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217
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Xu H, Oliveira-Sales EB, McBride F, Liu B, Hewinson J, Toward M, Hendy EB, Graham D, Dominiczak AF, Giannotta M, Waki H, Ascione R, Paton JFR, Kasparov S. Upregulation of junctional adhesion molecule-A is a putative prognostic marker of hypertension. Cardiovasc Res 2012; 96:552-60. [PMID: 22918977 PMCID: PMC3500047 DOI: 10.1093/cvr/cvs273] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Aims Establishing biochemical markers of pre-hypertension and early hypertension could help earlier diagnostics and therapeutic intervention. We assess dynamics of junctional adhesion molecule-A (JAM-A) expression in rat models of hypertension and test whether JAM-A expression could be driven by angiotensin (ANG) II and whether JAM-A contributes to the progression of hypertension. We also compare JAM-A expression in normo- and hypertensive humans. Methods and results In pre-hypertensive and spontaneously hypertensive rats (SHRs), JAM-A protein was overexpressed in the brainstem microvasculature, lung, liver, kidney, spleen, and heart. JAM-A upregulation at early and late stages was even greater in the stroke-prone SHR. However, JAM-A was not upregulated in leucocytes and platelets of SHRs. In Goldblatt 2K-1C hypertensive rats, JAM-A expression was augmented before any increase in blood pressure, and similarly JAM-A upregulation preceded hypertension caused by peripheral and central ANG II infusions. In SHRs, ANG II type 1 (AT1) receptor antagonism reduced JAM-A expression, but the vasodilator hydralazine did not. Body-wide downregulation of JAM-A with Vivo-morpholinos in juvenile SHRs delayed the progression of hypertension. In the human saphenous vein, JAM-A mRNA was elevated in hypertensive patients with untreated hypertension compared with normotensive patients but reduced in patients treated with renin–angiotensin system antagonists. Conclusion Body-wide upregulation of JAM-A in genetic and induced models of hypertension in the rat precedes the stable elevation of arterial pressure. JAM-A upregulation may be triggered by AT1 receptor-mediated signalling. An association of JAM-A with hypertension and sensitivity to blockers of ANG II signalling were also evident in humans. We suggest a prognostic and possibly a pathogenic role of JAM-A in arterial hypertension.
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Affiliation(s)
- Haibo Xu
- School of Physiology and Pharmacology, Bristol Heart Institute, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
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Harrison DG, Guzik TJ. Studies of the T-cell angiotensin receptor using cre-lox technology: an unan-T-cellpated result. Circ Res 2012; 110:1543-5. [PMID: 22679135 DOI: 10.1161/circresaha.112.271411] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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219
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Angiotensin II, Aldosterone, and Anti-Inflammatory Lymphocytes: Interplay and Therapeutic Opportunities. Int J Hypertens 2012; 2012:829786. [PMID: 22685633 PMCID: PMC3364573 DOI: 10.1155/2012/829786] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 03/13/2012] [Indexed: 02/07/2023] Open
Abstract
Inflammation is recognized as an important factor in the pathophysiology of hypertension, with the renin-angiotensin-aldosterone system (RAAS) playing a key role in the disease. Initially described because of its contribution to extracellular fluid and electrolyte homeostasis, the RAAS has been implicated in endothelial dysfunction, vascular remodeling, oxidative stress, proinflammatory cytokine production, and adhesion molecule synthesis by the vascular wall. Both angiotensin II and aldosterone are involved in these systemic effects, activating innate and adaptive immune responses. This paper highlights some aspects connecting RAAS to the hypertensive phenotype, based on experimental and clinical studies, with emphasis on new findings regarding the contribution of an increasingly studied population of T lymphocytes: the T-regulatory lymphocytes. These cells can suppress inflammation and may exert beneficial vascular effects in animal models of hypertension.
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220
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Harrison DG, Marvar PJ, Titze JM. Vascular inflammatory cells in hypertension. Front Physiol 2012; 3:128. [PMID: 22586409 PMCID: PMC3345946 DOI: 10.3389/fphys.2012.00128] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Accepted: 04/16/2012] [Indexed: 12/11/2022] Open
Abstract
Hypertension is a common disorder with uncertain etiology. In the last several years, it has become evident that components of both the innate and adaptive immune system play an essential role in hypertension. Macrophages and T cells accumulate in the perivascular fat, the heart and the kidney of hypertensive patients, and in animals with experimental hypertension. Various immunosuppressive agents lower blood pressure and prevent end-organ damage. Mice lacking lymphocytes are protected against hypertension, and adoptive transfer of T cells, but not B cells in the animals restores their blood pressure response to stimuli such as angiotensin II or high salt. Recent studies have shown that mice lacking macrophages have blunted hypertension in response to angiotensin II and that genetic deletion of macrophages markedly reduces experimental hypertension. Dendritic cells have also been implicated in this disease. Many hypertensive stimuli have triggering effects on the central nervous system and signals arising from the circumventricular organ seem to promote inflammation. Studies have suggested that central signals activate macrophages and T cells, which home to the kidney and vasculature and release cytokines, including IL-6 and IL-17, which in turn cause renal and vascular dysfunction and lead to blood pressure elevation. These recent discoveries provide a new understanding of hypertension and provide novel therapeutic opportunities for treatment of this serious disease.
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Affiliation(s)
- David G Harrison
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Nashville, TN, USA
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221
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Macrophage-stimulated cardiac fibroblast production of IL-6 is essential for TGF β/Smad activation and cardiac fibrosis induced by angiotensin II. PLoS One 2012; 7:e35144. [PMID: 22574112 PMCID: PMC3344835 DOI: 10.1371/journal.pone.0035144] [Citation(s) in RCA: 213] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 03/08/2012] [Indexed: 11/19/2022] Open
Abstract
Interleukin-6 (IL-6) is an important cytokine participating in multiple biologic activities in immune regulation and inflammation. IL-6 has been associated with cardiovascular remodeling. However, the mechanism of IL-6 in hypertensive cardiac fibrosis is still unclear. Angiotensin II (Ang II) infusion in mice increased IL-6 expression in the heart. IL-6 knockout (IL-6-/-) reduced Ang II-induced cardiac fibrosis: 1) Masson trichrome staining showed that Ang II infusion significantly increased fibrotic areas of the wild-type mouse heart, which was greatly suppressed in IL-6-/- mice and 2) immunohistochemistry staining showed decreased expression of α-smooth muscle actin (α-SMA), transforming growth factor β1 (TGF-β1) and collagen I in IL-6-/- mouse heart. The baseline mRNA expression of IL-6 in cardiac fibroblasts was low and was absent in cardiomyocytes or macrophages; however, co-culture of cardiac fibroblasts with macrophages significantly increased IL-6 production and expression of α-SMA and collagen I in fibroblasts. Moreover, TGF-β1 expression and phosphorylation of TGF-β downstream signal Smad3 was stimulated by co-culture of macrophages with cardiac fibroblasts, while IL-6 neutralizing antibody decreased TGF-β1 expression and Smad3 phosphorylation in co-culture of macrophage and fibroblast. Taken together, our results indicate that macrophages stimulate cardiac fibroblasts to produce IL-6, which leads to TGF-β1 production and Smad3 phosphorylation in cardiac fibroblasts and thus stimulates cardiac fibrosis.
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Marvar PJ, Vinh A, Thabet S, Lob HE, Geem D, Ressler KJ, Harrison DG. T lymphocytes and vascular inflammation contribute to stress-dependent hypertension. Biol Psychiatry 2012; 71:774-82. [PMID: 22361077 PMCID: PMC3354001 DOI: 10.1016/j.biopsych.2012.01.017] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Revised: 12/20/2011] [Accepted: 01/13/2012] [Indexed: 02/07/2023]
Abstract
BACKGROUND Psychological stress is a significant risk factor for hypertension and also directly affects the immune system. We have previously reported that T lymphocytes are essential for development of hypertension and that the central nervous system contributes to peripheral T-lymphocyte activation and vascular inflammation in this disease; however, the role of T-cell activation in stress-related hypertension remains unclear. METHODS Wild-type and T-cell-deficient (RAG-1(-/-)) mice were subjected to daily episodes of stress and blood pressure was measured. Circulating T-cell activation markers and vascular infiltration of immune cells were analyzed, as were stress hormone levels and gene expression changes in the brain. The effects angiotensin II infusion in the presence of chronic stress was also studied. RESULTS Repeated daily stress contributed to acute elevations in blood pressure that were associated with increased activation of circulating T cells and increased vascular infiltration of T cells. Repeated stress increased blood pressure in wild-type but not RAG-1(-/-) mice. Adoptive transfer of T cells to RAG-1(-/-) mice restored blood pressure elevation in response to stress. Stress-related hypertension and vascular infiltration of T cells was markedly enhanced by angiotensin II. Moreover, angiotensin II-infused mice exposed to chronic stress exhibited greater blood pressure reactivity to an episode of acute stress. CONCLUSIONS These data demonstrate that stress-dependent hypertension triggers an inflammatory response that raises blood pressure at baseline and augments the hypertension caused by angiotensin II. These data provide insight as to how psychological stress contributes to hypertension.
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Affiliation(s)
- Paul J. Marvar
- Emory University School of Medicine Department of Psychiatry and the Center of Behavioral Sciences
| | - Antony Vinh
- Department of Pharmacology Monash University
| | - Salim Thabet
- Division of Clinical Pharmacology and Department of Medicine, Vanderbilt University School of Medicine
| | | | - Duke Geem
- Emory University Department of Pediatrics
| | - Kerry J. Ressler
- Emory University School of Medicine Department of Psychiatry and the Center of Behavioral Sciences,Howard Hughes Medical Institute
| | - David G. Harrison
- Division of Clinical Pharmacology and Department of Medicine, Vanderbilt University School of Medicine
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223
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Chandar J, Zilleruelo G. Hypertensive crisis in children. Pediatr Nephrol 2012; 27:741-51. [PMID: 21773822 DOI: 10.1007/s00467-011-1964-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 06/21/2011] [Accepted: 06/21/2011] [Indexed: 12/27/2022]
Abstract
Hypertensive crisis is rare in children and is usually secondary to an underlying disease. There is strong evidence that the renin-angiotensin system plays an important role in the genesis of hypertensive crisis. An important principle in the management of children with hypertensive crisis is to determine if severe hypertension is chronic, acute, or acute-on-chronic. When it is associated with signs of end-organ damage such as encephalopathy, congestive cardiac failure or renal failure, there is an emergent need to lower blood pressures to 25-30% of the original value and then accomplish a gradual reduction in blood pressure. Precipitous drops in blood pressure can result in impairment of perfusion of vital organs. Medications commonly used to treat hypertensive crisis in children are nicardipine, labetalol and sodium nitroprusside. In this review, we discuss the pathophysiology, differential diagnosis and recent developments in management of hypertensive crisis in children.
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Affiliation(s)
- Jayanthi Chandar
- Department of Pediatrics, Division of Pediatric Nephrology, Holtz Children's Hospital, University of Miami Miller School of Medicine, Miami, FL, USA
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224
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Abstract
Inflammation plays an important role in the pathogenesis of hypertension. Innate and adaptive immune response may contribute to this process. The mechanisms implicating immune response in hypertension are still elusive. To date, the evidence originates in three major areas of data: cytokine production, central nervous system (CNS) stimulation, and kidney damage. The cytokine microenvironment can become proinflammatory and propagate low-grade inflammation, which may contribute to vascular injury and end-organ damage in hypertension. In addition, stimulation of the CNS by some stimuli (e.g., angiotensin II) causes mild hypertension that may modulate peripheral immune responses leading to aggravation of blood pressure elevation. The immune response can induce kidney injury and also interfere with sodium excretion, further contributing to elevation of blood pressure. The purpose of this review is to discuss recent data regarding the contribution of the different immune cell subsets and their response and mechanism of action in promoting hypertension and target-organ damage.
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Affiliation(s)
- Avshalom Leibowitz
- Lady Davis Institute for Medical Research, McGill University, Montreal, PQ, Canada
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225
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Abstract
The renin-angiotensin system (RAS) exercises fundamental control over sodium and water handling in the kidney. Accordingly, dysregulation of the RAS leads to blood pressure elevation with ensuing renal and cardiovascular damage. Recent studies have revealed that the RAS hormonal cascade is more complex than initially posited with multiple enzymes, effector molecules, and receptors that coordinately regulate the effects of the RAS on the kidney and vasculature. Moreover, recently identified tissue-specific RAS components have pleomorphic effects independent of the circulating RAS that influence critical homeostatic mechanisms including the immune response and fetal development. Further characterization of the diverse interactions between the RAS and other signaling pathways within specific tissues should lead to novel treatments for renal and cardiovascular disease.
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226
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Fornasa G, Clement M, Groyer E, Gaston AT, Khallou-Laschet J, Morvan M, Guedj K, Kaveri SV, Tedgui A, Michel JB, Nicoletti A, Caligiuri G. A CD31-derived peptide prevents angiotensin II-induced atherosclerosis progression and aneurysm formation. Cardiovasc Res 2012; 94:30-7. [PMID: 22293851 DOI: 10.1093/cvr/cvs076] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
AIMS The loss of the inhibitory receptor CD31 on peripheral T lymphocytes is associated with the incidence of atherosclerotic complications such as abdominal aortic aneurysms (AAA) in patients and plaque thrombosis in mice. However, we have recently discovered that a small fragment of extracellular CD31 remains expressed on the surface of the apparently 'CD31-negative' T-cells and that it is possible to restore the CD31-mediated T-cell inhibition in vivo by using a synthetic CD31-derived peptide. Here, we wanted to evaluate the therapeutic potential of the peptide in an experimental model of accelerated atherosclerosis and AAA formation. METHODS AND RESULTS The effect of the murine CD31-derived peptide (aa 551-574, 1.5 mg/kg/day, sc) was evaluated on the extent of atherosclerotic plaques and the incidence of AAA in 28-week-old apolipoprotein E knockout mice (male, n ≥ 8/group) submitted to chronic angiotensin II infusion. The therapeutic mechanisms of the peptide were assessed by evaluating its effect on immune cell functions in vivo and in vitro. The prevalence of angiotensin II-induced AAA correlated with the loss of extracellular CD31 on T-cells. CD31 peptide treatment reduced both aneurysm formation and plaque size (P < 0.05 vs. control). Protection was associated with reduced perivascular leucocyte infiltration and T-cell activation in vivo. Functional in vitro studies showed that the peptide is able to suppress both T-cell and macrophage activation. CONCLUSION CD31 peptides could represent a new class of drugs intended to prevent the inflammatory cell processes, such as those underlying progression of atherosclerosis and development of AAA.
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Affiliation(s)
- Giulia Fornasa
- INSERM, UMRS 698, 46 rue Henri Huchard, F-75018 Paris, France
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Myocardial migration by fibroblast progenitor cells is blood pressure dependent in a model of angII myocardial fibrosis. Hypertens Res 2012; 35:449-56. [PMID: 22258030 DOI: 10.1038/hr.2011.217] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Activation of the renin-angiotensin system (RAS) is thought to promote myocardial fibrosis. However, it is unclear whether this physiological fibrotic response results from chronic hemodynamic stress or from direct cellular signaling. Male C57B/6 mice were randomly assigned to receive angiotensin II (AngII) (2.0 μg kg(-1) min(-1)), AngII+hydralazine (6.9 μg kg(-1) min(-1)) or saline (control) via osmotic pumps for 7 days. Blood pressure was measured via noninvasive plethysmography. Hearts were harvested and processed for analysis. Cellular infiltration and collagen deposition were analyzed using histological staining. Molecular mediators were assessed using quantitative RT-PCR. As previously described, animals that received AngII developed hypertension and multifocal cellular infiltration by SMA(+)/CD133(+) fibroblast progenitors followed by collagen deposition. The coadministration of hydralazine with AngII completely inhibited the hypertensive effects of AngII (P0.01) and resulted in minimal cellular infiltration and minimal collagen deposition. These findings were in the context of persistent RAS activation, which was evidenced by elevation in serum aldosterone levels in animals that received AngII or AngII+hydralazine compared with animals that received saline. At the molecular level, infusion of AngII resulted in the significant upregulation of profibrotic factors (connective tissue growth factor-7.8±0.7 fold), proinflammatory mediators (TNFα-4.6±0.8 fold; IL-1β-6.4±2.6 fold) and chemokines (CCL2-3.8±1.0 fold; CXCL12-3.2±0.4 fold), which were inhibited when hydralazine was also infused. We provide evidence that myocardial infiltration by fibroblast progenitor cells secondary to AngII and the resultant fibrosis can be prevented by the addition of hydralazine. Furthermore, the beneficial effects of hydralazine were observed while maintaining RAS activation, suggesting that the mechanism of fibrosis is blood pressure dependent.
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Erratum to “Angiotensin II, Aldosterone, and Anti-Inflammatory Lymphocytes: Interplay and Therapeutic Opportunities”. Int J Hypertens 2012. [PMCID: PMC3439976 DOI: 10.1155/2012/132598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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229
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Abstract
High plasmatic levels of aldosterone cause hypertension and contribute to progressive organ damage to the heart, vasculature, and kidneys. Recent studies have demonstrated a role for the immune system in these pathological processes. Aldosterone promotes an inflammatory state characterized by vascular infiltration of immune cells, reactive oxidative stress, and proinflammatory cytokine production. Further, cells of the adaptive immune system, such as T cells, seem to participate in the genesis of mineralocorticoid hormone-induced hypertension. In addition, the observation that aldosterone can promote CD4⁺ T-cell activation and Th17 polarization suggests that this hormone could contribute to the onset of autoimmunity. Here we discuss recent evidence supporting a significant involvement of the immune system, especially adaptive immunity, in the genesis of hypertension and organ damage induced by primary aldosteronism. In addition, possible new therapeutic approaches consisting of immunomodulator drugs to control exacerbated immune responses triggered by elevated aldosterone concentrations will be described.
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Jennings BL, Anderson LJ, Estes AM, Fang XR, Song CY, Campbell WB, Malik KU. Involvement of cytochrome P-450 1B1 in renal dysfunction, injury, and inflammation associated with angiotensin II-induced hypertension in rats. Am J Physiol Renal Physiol 2011; 302:F408-20. [PMID: 22088434 DOI: 10.1152/ajprenal.00542.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We investigated the contribution of cytochrome P-450 1B1 (CYP1B1) to renal dysfunction and organ damage associated with ANG II-induced hypertension in rats. ANG II (300 ng·kg(-1)·min(-1)) or vehicle were infused for 2 wk, with daily injections of a selective CYP1B1 inhibitor, 2,4,3',5'-tetramethoxystilbene (TMS; 300 μg/kg ip), or its vehicle. ANG II increased blood pressure and renal CYP1B1 activity that were prevented by TMS. ANG II also increased water intake and urine output, decreased glomerular filtration rate, increased urinary Na(+) and K(+) excretion, and caused proteinuria, all of which were prevented by TMS. ANG II infusion caused hypertrophy, endothelial dysfunction, and increased reactivity of renal and interlobar arteries to vasoconstrictor agents and renal vascular resistance and interstitial fibrosis as indicated by accumulation of α-smooth muscle actin, fibronectin, and collagen, and inflammation as indicated by increased infiltration of CD-3(+) cells; these effects were inhibited by TMS. ANG II infusion also increased production of reactive oxygen species (ROS) and activities of NADPH oxidase, ERK1/2, p38 MAPK, and c-Src that were prevented by TMS. TMS alone had no effect on any of the above parameters. These data suggest that CYP1B1 contributes to the renal pathophysiological changes associated with ANG II-induced hypertension, most likely via increased ROS production and activation of ERK1/2, p38 MAPK, and c-Src and that CYP1B1 could serve as a novel target for treating renal disease associated with hypertension.
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Affiliation(s)
- Brett L Jennings
- Dept. of Pharmacology, College of Medicine, Univ. of Tennessee Health Science Center, 874 Union Ave., Memphis, TN 38163, USA
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Abstract
High blood pressure, or hypertension, is a very common disorder with a substantial impact on public health because of its associated complications. Despite the high prevalence of essential hypertension and years of research, the basic causes remain obscure. Here I review recent advances in understanding the pathophysiology of hypertension. I present a general overview of the field and, by necessity, use broad strokes to portray recent progress and place it in context. For this purpose, I use illustrative examples from the large number of important developments in hypertension research over the last five years. The intent of this review is to provide a sense of where the field is progressing, with an emphasis on work that sheds light on pathogenic mechanisms and that is therefore likely to inform new translational advances.
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232
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Luft FC. Neural regulation of the immune system modulates hypertension-induced target-organ damage. ACTA ACUST UNITED AC 2011; 6:23-6. [PMID: 22047671 DOI: 10.1016/j.jash.2011.09.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 09/28/2011] [Indexed: 12/16/2022]
Abstract
Innate and acquired immune mechanisms are involved in hypertension-induced target-organ damage. Immunosuppressive treatments directed at T lymphocytes, NF-κB activation, or tumor necrosis factor-alpha production are all successful in ameliorating cardiac or renal injury. Recently, important modulatory functions involving the autonomic nervous system have been uncovered. Involved are an afferent detection arm that sends vagal-mediated signals to the brain and an efferent arm that includes the spleen and important nicotinic acetylcholine receptor subunit. The signaling attenuates inflammatory activity. Splenectomy or operations that injure the vagus or splenic abrogate these important protective mechanisms. Vagal stimulation, either electrical or pharmacological, could provide additional protection. The field of neuroimmunology will become increasingly important to cardiovascular clinicians.
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Affiliation(s)
- Friedrich C Luft
- Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany.
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Brain AT1 Receptor Activates the Sympathetic Nervous System Through Toll-like Receptor 4 in Mice With Heart Failure. J Cardiovasc Pharmacol 2011; 58:543-9. [DOI: 10.1097/fjc.0b013e31822e6b40] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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234
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Grisk O. Antihypertensive effects of ACE2 in the paraventricular nucleus: a consequence of reduced neuroinflammation? Cardiovasc Res 2011; 92:365-6. [DOI: 10.1093/cvr/cvr269] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Sriramula S, Cardinale JP, Lazartigues E, Francis J. ACE2 overexpression in the paraventricular nucleus attenuates angiotensin II-induced hypertension. Cardiovasc Res 2011; 92:401-8. [PMID: 21952934 DOI: 10.1093/cvr/cvr242] [Citation(s) in RCA: 148] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
AIMS Angiotensin II (Ang II) has been shown to have both central and peripheral effects in mediating hypertension, for which the hypothalamic paraventricular nucleus (PVN) is an important brain cardio-regulatory centre. Angiotensin-converting enzyme 2 (ACE2) has been identified as a negative regulator of the pro-hypertensive actions of Ang II. Recent findings from our laboratory suggest that Ang II infusion decreases ACE2 expression in the PVN. In the present study, we hypothesized that ACE2 overexpression in the PVN will have beneficial effects in counteracting Ang II-induced hypertension. METHODS AND RESULTS Male Sprague-Dawley rats were used in this study. Bilateral microinjection of an adenovirus encoding hACE2 (Ad-ACE2) into the PVN was used to overexpress ACE2 within this region. Mean arterial pressure measured by radiotelemetry was significantly increased after 14 days in Ang II-infused (200 ng/kg/min) rats vs. saline-infused controls (162.9 ± 3.6 vs. 102.3 ± 1.5 mmHg). Bilateral PVN microinjection of Ad-ACE2 attenuated this Ang II-induced hypertension (130.2 ± 5.7 vs. 162.9 ± 3.6 mmHg). ACE2 overexpression also significantly decreased AT(1)R and ACE expression and increased AT(2)R and Mas expression in the PVN. Additionally, ACE2 overexpression in the PVN attenuated the Ang II-induced increase in the expression of the pro-inflammatory cytokines tumour necrosis factor-α, interleukin (IL)-1β and IL-6 in the PVN. CONCLUSION Our findings suggest that attenuation of pro-inflammatory cytokines in the PVN in combination with the shift of the renin-angiotensin system towards the anti-hypertensive axis (ACE2/Ang-(1-7)/Mas) may be responsible for the overall beneficial effects of ACE2 overexpression in the PVN on the Ang II-induced hypertensive response.
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Affiliation(s)
- Srinivas Sriramula
- Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, 1909 Skip Bertman Drive, Baton Rouge, LA 70803, USA
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Savoia C, Sada L, Zezza L, Pucci L, Lauri FM, Befani A, Alonzo A, Volpe M. Vascular inflammation and endothelial dysfunction in experimental hypertension. Int J Hypertens 2011; 2011:281240. [PMID: 21915370 PMCID: PMC3170891 DOI: 10.4061/2011/281240] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 07/12/2011] [Indexed: 12/11/2022] Open
Abstract
Essential hypertension is characterized by increased peripheral vascular resistance to blood flow. The endothelium is a crucial regulator of vascular tone. Its function is impaired in patients with hypertension, with reduced vasodilation, increased vascular tone associated with a proinflammatory and prothrombotic state. Low-grade inflammation localized in vascular tissue is therefore recognized as an important contributor to the pathophysiology of hypertension, to the initiation and progression of atherosclerosis as well as to the development of cardiovascular diseases.
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Affiliation(s)
- Carmine Savoia
- Cardiology Unit, Clinical and Molecular Medicine Department, Sant'Andrea Hospital, Sapienza University of Rome, Via di Grottarossa 1037/1039, 00189 Rome, Italy
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Booz GW. Cannabidiol as an emergent therapeutic strategy for lessening the impact of inflammation on oxidative stress. Free Radic Biol Med 2011; 51:1054-61. [PMID: 21238581 PMCID: PMC3085542 DOI: 10.1016/j.freeradbiomed.2011.01.007] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 01/04/2011] [Accepted: 01/05/2011] [Indexed: 12/24/2022]
Abstract
Oxidative stress with reactive oxygen species generation is a key weapon in the arsenal of the immune system for fighting invading pathogens and initiating tissue repair. If excessive or unresolved, however, immune-related oxidative stress can initiate further increasing levels of oxidative stress that cause organ damage and dysfunction. Targeting oxidative stress in various diseases therapeutically has proven more problematic than first anticipated given the complexities and perversity of both the underlying disease and the immune response. However, growing evidence suggests that the endocannabinoid system, which includes the CB₁ and CB₂ G-protein-coupled receptors and their endogenous lipid ligands, may be an area that is ripe for therapeutic exploitation. In this context, the related nonpsychotropic cannabinoid cannabidiol, which may interact with the endocannabinoid system but has actions that are distinct, offers promise as a prototype for anti-inflammatory drug development. This review discusses recent studies suggesting that cannabidiol may have utility in treating a number of human diseases and disorders now known to involve activation of the immune system and associated oxidative stress, as a contributor to their etiology and progression. These include rheumatoid arthritis, types 1 and 2 diabetes, atherosclerosis, Alzheimer disease, hypertension, the metabolic syndrome, ischemia-reperfusion injury, depression, and neuropathic pain.
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Affiliation(s)
- George W Booz
- Department of Pharmacology and Toxicology, School of Medicine, and Center for Excellence in Cardiovascular-Renal Research, University of Mississippi Medical Center, Jackson, MS 39216, USA.
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Crowley SD, Zhang J, Herrera M, Griffiths R, Ruiz P, Coffman TM. Role of AT₁ receptor-mediated salt retention in angiotensin II-dependent hypertension. Am J Physiol Renal Physiol 2011; 301:F1124-30. [PMID: 21849491 DOI: 10.1152/ajprenal.00305.2011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Activation of type 1 angiotensin II (AT(1)) receptors in the kidney promotes blood pressure elevation and target organ damage, but whether renal AT(1) receptors influence the level of hypertension by stimulating sodium retention or by raising systemic vascular resistance has not been established. In the current studies, we used a kidney cross-transplantation strategy to determine whether increased sodium reabsorption by AT(1) receptors in the kidney mediates the chronic hypertensive response to angiotensin II. We found this to be true. In addition, we also identified a second, nontrivial component of blood pressure elevation induced by activation of renal AT(1) receptors that is sodium-independent. As the kidney has the capacity to limit the transmission of elevated systemic blood pressure into the renal microcirculation, prior studies struggled to clearly discriminate the relative contributions of blood pressure elevation vs. activation of AT(1) receptors to hypertensive kidney injury. In our model, we found that rapid surges in blood pressure, which may overcome the kidney's capacity to prevent perturbations in renal hemodynamics, correlate closely with kidney damage in hypertension. Moreover, maximal kidney injury in hypertension may require activation of a pool of nonrenal, systemic AT(1) receptors. These studies provide insight into precise mechanisms through which AT(1) receptor blockade influences the progression of hypertensive kidney disease.
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Affiliation(s)
- Steven D Crowley
- Division of Nephrology, Department of Medicine, Duke University Medical Center and Durham Veterans Affairs Medical Center, Durham, North Carolina, USA.
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239
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The sympathetic nervous system and blood pressure in humans: implications for hypertension. J Hum Hypertens 2011; 26:463-75. [PMID: 21734720 DOI: 10.1038/jhh.2011.66] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A neurogenic component to primary hypertension (hypertension) is now well established. Along with raised vasomotor tone and increased cardiac output, the chronic activation of the sympathetic nervous system in hypertension has a diverse range of pathophysiological consequences independent of any increase in blood pressure. This review provides a perspective on the actions and interactions of angiotensin II, inflammation and vascular dysfunction/brain hypoperfusion in the pathogenesis and progression of neurogenic hypertension. The optimisation of current treatment strategies and the exciting recent developments in the therapeutic targeting of the sympathetic nervous system to control hypertension (for example, catheter-based renal denervation and carotid baroreceptor stimulation) will be outlined.
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240
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Chu PY, Zatta A, Kiriazis H, Chin-Dusting J, Du XJ, Marshall T, Kaye DM. CXCR4 antagonism attenuates the cardiorenal consequences of mineralocorticoid excess. Circ Heart Fail 2011; 4:651-8. [PMID: 21685249 DOI: 10.1161/circheartfailure.110.960831] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Extensive evidence implicates aldosterone excess in the development and progression of cardiovascular disease states including hypertension, metabolic syndrome, cardiac hypertrophy, heart failure, and cardiorenal fibrosis. Recent studies show that activation of inflammatory cascade may play a specific role in the sequelae of mineralocorticoid activation, although the linking mechanism remains unclear. We tested the possibility that secondary stimulation of the stromal-derived factor 1/CXC chemokine receptor 4 (SDF-1/CXCR4) pathway plays a contributory role. METHODS AND RESULTS We investigated the effect of the highly selective CXCR4 antagonist AMD3465 (6 mg/kg per day for 6 weeks through minipump) in dexoycorticosterone acetate (DOCA)-treated, uninephrectomized mice. CXCR4 antagonism significantly attenuated the induction of cardiac fibrosis, renal fibrosis, hypertension, and left ventricular hypertrophy by DOCA. Mineralocorticoid excess also stimulated the accumulation of T-lymphocytes in the heart and kidney and this was significantly blunted by CXCR4 inhibition. CONCLUSIONS Taken together, these data strongly implicate the SDF-1/CXCR4 axis in the pathogenesis of mineralocorticoid excess induced hypertension, inflammation, and cardiorenal fibrosis. This insight provides a new potential therapeutic approach for the treatment of specific aspects of mineralocorticoid mediated cardiovascular disease.
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Affiliation(s)
- Po-Yin Chu
- Heart Failure Research Group, Baker IDI Heart and Diabetes Research Institute, Melbourne, Australia
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241
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Drummond GR, Selemidis S, Griendling KK, Sobey CG. Combating oxidative stress in vascular disease: NADPH oxidases as therapeutic targets. Nat Rev Drug Discov 2011; 10:453-71. [PMID: 21629295 PMCID: PMC3361719 DOI: 10.1038/nrd3403] [Citation(s) in RCA: 690] [Impact Index Per Article: 53.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
NADPH oxidases are a family of enzymes that generate reactive oxygen species (ROS). The NOX1 (NADPH oxidase 1) and NOX2 oxidases are the major sources of ROS in the artery wall in conditions such as hypertension, hypercholesterolaemia, diabetes and ageing, and so they are important contributors to the oxidative stress, endothelial dysfunction and vascular inflammation that underlies arterial remodelling and atherogenesis. In this Review, we advance the concept that compared to the use of conventional antioxidants, inhibiting NOX1 and NOX2 oxidases is a superior approach for combating oxidative stress. We briefly describe some common and emerging putative NADPH oxidase inhibitors. In addition, we highlight the crucial role of the NADPH oxidase regulatory subunit, p47phox, in the activity of vascular NOX1 and NOX2 oxidases, and suggest how a better understanding of its specific molecular interactions may enable the development of novel isoform-selective drugs to prevent or treat cardiovascular diseases.
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Affiliation(s)
- Grant R Drummond
- Vascular Biology & Immunopharmacology Group, Department of Pharmacology, Monash University, Victoria 3800, Australia.
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242
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Waki H, Gouraud SS, Maeda M, Raizada MK, Paton JFR. Contributions of vascular inflammation in the brainstem for neurogenic hypertension. Respir Physiol Neurobiol 2011; 178:422-8. [PMID: 21601658 DOI: 10.1016/j.resp.2011.05.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 05/06/2011] [Accepted: 05/06/2011] [Indexed: 02/07/2023]
Abstract
Essential hypertension is idiopathic although it is accepted as a complex polygenic trait with underlying genetic components, which remain unknown. Our supposition is that primary hypertension involves activation of the sympathetic nervous system. One pivotal region controlling arterial pressure set point is nucleus tractus solitarii (NTS). We recently identified that pro-inflammatory molecules, such as junctional adhesion molecule-1, were over expressed in endothelial cells of the microvasculature supplying the NTS in an animal model of human hypertension (the spontaneously hypertensive rat: SHR) compared to normotensive Wistar Kyoto (WKY) rats. We have also shown endogenous leukocyte accumulation inside capillaries within the NTS of SHR but not WKY rats. Despite the inflammatory state in the NTS of SHR, transcripts of some inflammatory molecules such as chemokine (C-C motif) ligand 5 (Ccl5), and its receptors, chemokine (C-C motif) receptor 1 and 3 were down-regulated in the NTS of SHR compared to WKY rats. This may be compensatory to avoid further strong inflammatory activity. More importantly, we found that down-regulation of Ccl5 in the NTS of SHR may be pro-hypertensive since microinjection of Ccl5 into the NTS of SHR decreased arterial pressure but was less effective in WKY rats. Leukocyte accumulation of the NTS microvasculature may also induce an increase in vascular resistance and hypoperfusion within the NTS; the latter may trigger release of pro-inflammatory molecules which via paracrine signaling may affect central neural cardiovascular activity conducive to neurogenic hypertension. All told, we suggest that vascular inflammation within the brainstem contributes to neurogenic hypertension by multiple pathways.
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Affiliation(s)
- Hidefumi Waki
- Department of Physiology, Wakayama Medical University School of Medicine, Wakayama 641-8509, Japan.
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243
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Zubcevic J, Waki H, Raizada MK, Paton JFR. Autonomic-immune-vascular interaction: an emerging concept for neurogenic hypertension. Hypertension 2011; 57:1026-33. [PMID: 21536990 DOI: 10.1161/hypertensionaha.111.169748] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jasenka Zubcevic
- Department of Physiology and Functional Genomics, McKnight Brain Institute, 1600 SW Archer Rd, Gainesville, FL 32610, USA
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244
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Abstract
Hypertension is associated with vascular changes characterised by remodelling, endothelial dysfunction and hyperreactivity. Cellular processes underlying these perturbations include altered vascular smooth muscle cell growth and apoptosis, fibrosis, hypercontractility and calcification. Inflammation, associated with macrophage infiltration and increased expression of redox-sensitive pro-inflammatory genes, also contributes to vascular remodelling. Many of these features occur with ageing, and the vascular phenotype in hypertension is considered a phenomenon of ‘premature vascular ageing’. Among the many factors involved in the hypertensive vascular phenotype, angiotensin II (Ang II) is especially important. Ang II, previously thought to be the sole effector of the renin–angiotensin system (RAS), is converted to smaller peptides [Ang III, Ang IV, Ang-(1-7)] that are biologically active in the vascular system. Another new component of the RAS is the (pro)renin receptor, which signals through Ang-II-independent mechanisms and might influence vascular function. Ang II mediates effects through complex signalling pathways on binding to its G-protein-coupled receptors (GPCRs) AT1R and AT2R. These receptors are regulated by the GPCR-interacting proteins ATRAP, ARAP1 and ATIP. AT1R activation induces effects through the phospholipase C pathway, mitogen-activated protein kinases, tyrosine kinases/phosphatases, RhoA/Rhokinase and NAD(P)H-oxidase-derived reactive oxygen species. Here we focus on recent developments and new research trends related to Ang II and the RAS and involvement in the hypertensive vascular phenotype.
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Angiotensin II Infusion–Induced Inflammation, Monocytic Fibroblast Precursor Infiltration, and Cardiac Fibrosis are Pressure Dependent. Cardiovasc Toxicol 2011; 11:157-67. [DOI: 10.1007/s12012-011-9109-z] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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248
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The central nervous system and inflammation in hypertension. Curr Opin Pharmacol 2010; 11:156-61. [PMID: 21196131 DOI: 10.1016/j.coph.2010.12.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 11/30/2010] [Accepted: 12/06/2010] [Indexed: 02/07/2023]
Abstract
In recent years a major research effort has focused on the role of inflammation, and in particular adaptive immunity, in the genesis of hypertension. Hypertension stimulates the accumulation of inflammatory cells including macrophages and T lymphocytes in peripheral tissues important in blood pressure control, such as the kidney and vasculature. Angiotensin II modulates blood pressure via actions on the central nervous system (CNS) and the adaptive immune system. Recent work suggests that the central actions of angiotensin II via the circumventricular organs lead to activation of circulating T-cells and vascular inflammation. The neuro-immune system plays an essential role in the pathogenesis of hypertension and further understanding of this relationship could lead to the development of new treatment strategies.
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249
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Zhong J, Guo D, Chen CB, Wang W, Schuster M, Loibner H, Penninger JM, Scholey JW, Kassiri Z, Oudit GY. Prevention of angiotensin II-mediated renal oxidative stress, inflammation, and fibrosis by angiotensin-converting enzyme 2. Hypertension 2010; 57:314-22. [PMID: 21189404 DOI: 10.1161/hypertensionaha.110.164244] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Angiotensin-converting enzyme 2 (ACE2) is a monocarboxypeptidase capable of metabolizing angiotensin (Ang) II into Ang 1 to 7. We hypothesized that ACE2 is a negative regulator of Ang II signaling and its adverse effects on the kidneys. Ang II infusion (1.5 mg/kg⁻¹/d⁻¹) for 4 days resulted in higher renal Ang II levels and increased nicotinamide adenine dinucleotide phosphate oxidase activity in ACE2 knockout (Ace2(-/y)) mice compared to wild-type mice. Expression of proinflammatory cytokines, interleukin-1β and chemokine (C-C motif) ligand 5, were increased in association with greater activation of extracellular-regulated kinase 1/2 and increase of protein kinase C-α levels. These changes were associated with increased expression of fibrosis-associated genes (α-smooth muscle actin, transforming growth factor-β, procollagen type Iα1) and increased protein levels of collagen I with histological evidence of increased tubulointerstitial fibrosis. Ang II-infused wild-type mice were then treated with recombinant human ACE2 (2 mg/kg⁻¹/d⁻¹, intraperitoneal). Daily treatment with recombinant human ACE2 reduced Ang II-induced pressor response and normalized renal Ang II levels and oxidative stress. These changes were associated with a suppression of Ang II-mediated activation of extracellular-regulated kinase 1/2 and protein kinase C pathway and Ang II-mediated renal fibrosis and T-lymphocyte-mediated inflammation. We conclude that loss of ACE2 enhances renal Ang II levels and Ang II-induced renal oxidative stress, resulting in greater renal injury, whereas recombinant human ACE2 prevents Ang II-induced hypertension, renal oxidative stress, and tubulointerstitial fibrosis. ACE2 is an important negative regulator of Ang II-induced renal disease and enhancing ACE2 action may have therapeutic potential for patients with kidney disease.
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Affiliation(s)
- JiuChang Zhong
- Division of Cardiology, Department of Medicine, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
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250
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Harrison DG, Guzik TJ, Lob HE, Madhur MS, Marvar PJ, Thabet SR, Vinh A, Weyand CM. Inflammation, immunity, and hypertension. Hypertension 2010; 57:132-40. [PMID: 21149826 DOI: 10.1161/hypertensionaha.110.163576] [Citation(s) in RCA: 589] [Impact Index Per Article: 42.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- David G Harrison
- Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN 37232-6602, USA.
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