1
|
COVID-19: imbalance of multiple systems during infection and importance of therapeutic choice and dosing of cardiac and anti-coagulant therapies. Mol Biol Rep 2021; 48:2917-2928. [PMID: 33837899 PMCID: PMC8035598 DOI: 10.1007/s11033-021-06333-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 04/01/2021] [Indexed: 12/26/2022]
Abstract
The renin-angiotensin-aldosterone system and its metabolites play an important role in homeostasis of body, especially the cardiovascular system. In this study, we discuss the imbalance of multiple systems during the infection and the importance of therapeutic choice, dosing, and laboratory monitoring of cardiac and anti-coagulant therapies in COVID-19 patients. The crosstalk between angiotensin, kinin-kallikrein system, as well as inflammatory and coagulation systems plays an essential role in COVID-19. Cardiac complications and coagulopathies imply the crosstalks between the mentioned systems. We believe that the blockage of bradykinin can be a good option in the management of COVID-19 and CVD in patients and that supportive treatment of respiratory and cardiologic complications is needed in COVID-19 patients. Ninety-one percent of COVID-19 patients who were admitted to hospital with a prolonged aPTT were positive for lupus anticoagulant, which increases the risk of thrombosis and prolonged aPTT. Therefore, the question that is posed at this juncture is whether it is safe to use the prophylactic dose of heparin particularly in those with elevated D-dimer levels. It should be noted that timing is of high importance in anti-coagulant therapy; therefore, we should consider the level of D-dimer, fibrinogen, drug-drug interactions, and risk factors during thromboprophylaxis administration. Fibrinogen is an independent predictor of resistance to heparin and should be considered before thromboprophylaxis. Alteplase and Futhan might be a good choice to assess the condition of heparin resistance. Finally, the treatment option, dosing, and laboratory monitoring of anticoagulant therapy are critical decisions in COVID-19 patients.
Collapse
|
2
|
Wijnant SRA, Jacobs M, Van Eeckhoutte HP, Lapauw B, Joos GF, Bracke KR, Brusselle GG. Expression of ACE2, the SARS-CoV-2 Receptor, in Lung Tissue of Patients With Type 2 Diabetes. Diabetes 2020; 69:2691-2699. [PMID: 33024003 DOI: 10.2337/db20-0669] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/30/2020] [Indexed: 01/01/2023]
Abstract
Increased expression of pulmonary ACE2, the SARS-CoV-2 receptor, could contribute to increased infectivity of COVID-19 in patients with diabetes, but ACE2 expression has not been studied in lung tissue of subjects with diabetes. We therefore studied ACE2 mRNA and protein expression in lung tissue samples of subjects with and without diabetes that were collected between 2002 and 2020 from patients undergoing lobectomy for lung tumors. For RT-PCR analyses, samples from 15 subjects with diabetes were compared with 91 randomly chosen control samples. For immunohistochemical staining, samples from 26 subjects with diabetes were compared with 66 randomly chosen control samples. mRNA expression of ACE2 was measured by quantitative RT-PCR. Protein levels of ACE2 were visualized by immunohistochemistry on paraffin-embedded lung tissue samples and quantified in alveolar and bronchial epithelium. Pulmonary ACE2 mRNA expression was not different between subjects with or without diabetes. In contrast, protein levels of ACE2 were significantly increased in both alveolar tissue and bronchial epithelium of patients with diabetes compared with control subjects, independent of smoking, chronic obstructive pulmonary disease, BMI, renin-angiotensin-aldosterone system inhibitor use, and other potential confounders. To conclude, we show increased bronchial and alveolar ACE2 protein expression in patients with diabetes. Further research is needed to elucidate whether upregulation of ACE2 expression in airways and lungs has consequences on infectivity and clinical outcomes of COVID-19.
Collapse
Affiliation(s)
- Sara R A Wijnant
- Laboratory for Translational Research in Obstructive Pulmonary Diseases, Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
- Department of Respiratory Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Merel Jacobs
- Laboratory for Translational Research in Obstructive Pulmonary Diseases, Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
| | - Hannelore P Van Eeckhoutte
- Laboratory for Translational Research in Obstructive Pulmonary Diseases, Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
| | - Bruno Lapauw
- Department of Endocrinology, Ghent University Hospital, Ghent, Belgium
| | - Guy F Joos
- Laboratory for Translational Research in Obstructive Pulmonary Diseases, Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
| | - Ken R Bracke
- Laboratory for Translational Research in Obstructive Pulmonary Diseases, Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
| | - Guy G Brusselle
- Laboratory for Translational Research in Obstructive Pulmonary Diseases, Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Respiratory Diseases, Erasmus Medical Center, Rotterdam, the Netherlands
| |
Collapse
|
3
|
A proposed mechanism for the Berecek phenomenon with implications for cardiovascular reprogramming. ACTA ACUST UNITED AC 2018; 12:644-651. [PMID: 30220305 DOI: 10.1016/j.jash.2018.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 06/15/2018] [Indexed: 01/29/2023]
Abstract
Berecek et al reported in the 1990s that when spontaneously hypertensive rat (SHR) mating pairs were treated with captopril and the resulting pups were continued on the drug for 2 months followed by drug discontinuation, the pups did not develop full blown hypertension, and the cardiovascular structural changes associated with hypertension in SHR were mitigated. The offspring of the pups also displayed diminished hypertension and structural changes, suggesting that the drug therapy produced a heritable amelioration of the SHR phenotype. This observation is reviewed. The link between cellular renin angiotensin systems and epigenetic histone modification is explored, and a mechanism responsible for the observation is proposed. In any case, the observations of Berecek are sufficiently intriguing and biologically important to merit re-exploration and definitive explanation. Equally important is determining the role of renin angiotensin systems in epigenetic modification.
Collapse
|
4
|
Ferrão FM, Lara LS, Lowe J. Renin-angiotensin system in the kidney: What is new? World J Nephrol 2014; 3:64-76. [PMID: 25332897 PMCID: PMC4202493 DOI: 10.5527/wjn.v3.i3.64] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 07/07/2014] [Accepted: 07/29/2014] [Indexed: 02/06/2023] Open
Abstract
The renin-angiotensin system (RAS) has been known for more than a century as a cascade that regulates body fluid balance and blood pressure. Angiotensin II(Ang II) has many functions in different tissues; however it is on the kidney that this peptide exerts its main functions. New enzymes, alternative routes for Ang IIformation or even active Ang II-derived peptides have now been described acting on Ang II AT1 or AT2 receptors, or in receptors which have recently been cloned, such as Mas and AT4. Another interesting observation was that old members of the RAS, such as angiotensin converting enzyme (ACE), renin and prorenin, well known by its enzymatic activity, can also activate intracellular signaling pathways, acting as an outside-in signal transduction molecule or on the renin/(Pro)renin receptor. Moreover, the endocrine RAS, now is also known to have paracrine, autocrine and intracrine action on different tissues, expressing necessary components for local Ang II formation. This in situ formation, especially in the kidney, increases Ang II levels to regulate blood pressure and renal functions. These discoveries, such as the ACE2/Ang-(1-7)/Mas axis and its antangonistic effect rather than classical deleterious Ang II effects, improves the development of new drugs for treating hypertension and cardiovascular diseases.
Collapse
|
5
|
Feldman DL, Jin L, Xuan H, Persohn E, Zhou W, Schuetz H, Park JK, Muller DN, Luft FC. The direct renin inhibitor aliskiren localizes and persists in rat kidneys. Am J Physiol Renal Physiol 2013; 305:F1593-602. [PMID: 23926182 DOI: 10.1152/ajprenal.00655.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The aims of this study were to 1) determine whether renal localization of aliskiren and its antihypertensive and renoprotective effects persist after administration of the drug is stopped and 2) define the renal localization of aliskiren by light microscopy autoradiography. Hypertensive double transgenic rats (dTGR) overexpressing genes for human renin and angiotensinogen were treated with aliskiren (3 mg·kg(-1)·day(-1) sc; osmotic minipumps) or enalapril (18 mg/l in drinking water). After a 2-wk treatment, dTGR were assigned to either continued treatment with aliskiren ("continued"), or to cessation of their respective treatment ("stopped") for a 3-wk washout. One week of treatment with aliskiren and enalapril reduced blood pressure and albuminuria vs. baseline. After cessation of either treatment, blood pressure had returned to pretreatment levels and albuminuria remained relatively low for 1 wk, but rose thereafter similarly in both groups. In contrast, renal mRNA for transforming growth factor-β and renal collagen IV was reduced by aliskiren (continued and stopped groups), but not after cessation of enalapril. Similar patterns were found for collagen IV protein expression. Even 3 wk after stopping aliskiren treatment, renal levels of the drug exceeded its IC50, whereas enalaprilat was not detected. To localize aliskiren accumulation, Wistar rats were treated with [(3)H]-aliskiren for 7 days. Autoradiography demonstrated specific labeling in glomeruli, arterioles, and afferent arterioles as well as in the distal nephron. Labeling could still be observed even after 7 days' washout. These results suggest that the renophilic properties of aliskiren are different from enalapril and could have contributed to the renoprotective mechanism of this renin inhibitor.
Collapse
Affiliation(s)
- David L Feldman
- Novartis Institutes for Biomedical Research, Bldg. 437, Rm. 3317, One Health Plaza, East Hanover, NJ 07936.
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Abadir PM, Walston JD, Carey RM. Subcellular characteristics of functional intracellular renin-angiotensin systems. Peptides 2012; 38:437-45. [PMID: 23032352 PMCID: PMC3770295 DOI: 10.1016/j.peptides.2012.09.016] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 09/14/2012] [Indexed: 02/06/2023]
Abstract
The renin-angiotensin system (RAS) is now regarded as an integral component in not only the development of hypertension, but also in physiologic and pathophysiologic mechanisms in multiple tissues and chronic disease states. While many of the endocrine (circulating), paracrine (cell-to-different cell) and autacrine (cell-to-same cell) effects of the RAS are believed to be mediated through the canonical extracellular RAS, a complete, independent and differentially regulated intracellular RAS (iRAS) has also been proposed. Angiotensinogen, the enzymes renin and angiotensin-converting enzyme (ACE) and the angiotensin peptides can all be synthesized and retained intracellularly. Angiotensin receptors (types I and 2) are also abundant intracellularly mainly at the nuclear and mitochondrial levels. The aim of this review is to focus on the most recent information concerning the subcellular localization, distribution and functions of the iRAS and to discuss the potential consequences of activation of the subcellular RAS on different organ systems.
Collapse
Affiliation(s)
- Peter M. Abadir
- Division of Geriatric Medicine and Gerontology, Biology of Healthy Aging Program, Johns Hopkins University School of Medicine, Baltimore, MD 21224, United States
| | - Jeremy D. Walston
- Division of Geriatric Medicine and Gerontology, Biology of Healthy Aging Program, Johns Hopkins University School of Medicine, Baltimore, MD 21224, United States
| | - Robert M. Carey
- Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908, United States
- Corresponding author at: P.O. Box 801414, University of Virginia Health System, Charlottesville, VA 22908-1414, United States. Tel.: +1 434 924 5510; fax: +1 434 982 3626. (R.M. Carey)
| |
Collapse
|
7
|
Abstract
The RAS (renin-angiotensin system) is one of the earliest and most extensively studied hormonal systems. The RAS is an atypical hormonal system in several ways. The major bioactive peptide of the system, AngII (angiotensin II), is neither synthesized in nor targets one specific organ. New research has identified additional peptides with important physiological and pathological roles. More peptides also mean newer enzymatic cascades that generate these peptides and more receptors that mediate their function. In addition, completely different roles of components that constitute the RAS have been uncovered, such as that for prorenin via the prorenin receptor. Complexity of the RAS is enhanced further by the presence of sub-systems in tissues, which act in an autocrine/paracrine manner independent of the endocrine system. The RAS seems relevant at the cellular level, wherein individual cells have a complete system, termed the intracellular RAS. Thus, from cells to tissues to the entire organism, the RAS exhibits continuity while maintaining independent control at different levels. The intracellular RAS is a relatively new concept for the RAS. The present review provides a synopsis of the literature on this system in different tissues.
Collapse
|
8
|
Kumar R, Yong QC, Thomas CM, Baker KM. Intracardiac intracellular angiotensin system in diabetes. Am J Physiol Regul Integr Comp Physiol 2011; 302:R510-7. [PMID: 22170614 DOI: 10.1152/ajpregu.00512.2011] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The renin-angiotensin system (RAS) has mainly been categorized as a circulating and a local tissue RAS. A new component of the local system, known as the intracellular RAS, has recently been described. The intracellular RAS is defined as synthesis and action of ANG II intracellularly. This RAS appears to differ from the circulating and the local RAS, in terms of components and the mechanism of action. These differences may alter treatment strategies that target the RAS in several pathological conditions. Recent work from our laboratory has demonstrated significant upregulation of the cardiac, intracellular RAS in diabetes, which is associated with cardiac dysfunction. Here, we have reviewed evidence supporting an intracellular RAS in different cell types, ANG II's actions in cardiac cells, and its mechanism of action, focusing on the intracellular cardiac RAS in diabetes. We have discussed the significance of an intracellular RAS in cardiac pathophysiology and implications for potential therapies.
Collapse
Affiliation(s)
- Rajesh Kumar
- Division of Molecular Cardiology, Texas A&M Health Science Center, College of Medicine, Temple, TX 76504, USA
| | | | | | | |
Collapse
|
9
|
Jak2-Independent Activation of Stat3 by Intracellular Angiotensin II in Human Mesangial Cells. JOURNAL OF SIGNAL TRANSDUCTION 2011; 2011:257862. [PMID: 21915376 PMCID: PMC3171157 DOI: 10.1155/2011/257862] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/12/2011] [Accepted: 06/07/2011] [Indexed: 01/13/2023]
Abstract
Ang II is shown to
mediate the stimulatory effect of high glucose
on TGF-b1 and extracellular matrix proteins in
glomerular mesangial cells. Also inhibition of Ang II formation
in cell media (extracellular) and lysates
(intracellular) blocks high-glucose effects on
TGF-b1 and matrix more effectively compared to
inhibition of extracellular Ang II alone. To investigate whether
intracellular Ang II can stimulate TGF-b1 and
matrix independent of extracellular Ang II,
cultured human mesangial cells were transfected
with Ang II to increase intracellular Ang II
levels and its effects on TGF-b1 and matrix
proteins were determined. Prior to transfection,
cells were treated with candesartan to block
extracellular Ang II-induced responses via cell
membrane AT1 receptors. Transfection of cells
with Ang II resulted in increased levels of
intracellular Ang II which was accompanied by
increased production of TGF-b1, collagen IV,
fibronectin, and cell proliferation as well. On
further examination, intracellular Ang II was
found to activate Stat3 transcription factor
including increased Stat3 protein expression,
tyrosine 705 phosphorylation, and DNA-binding
activity. Treatment with AG-490, an inhibitor of
Jak2, did not block intracellular Ang II-induced
Stat3 phosphorylation at tyrosine 705 residue
indicating a Jak2-independent mechanism used by
intracellular Ang II for Stat3 phosphorylation.
In contrast, extracellular Ang II-induced
tyrosine 705 phosphorylation of Stat3 was
inhibited by AG-490 confirming the presence of a
Jak2-dependent pathway. These findings suggest
that intracellular Ang II increases TGF-b1 and
matrix in human mesangial cells and also
activates Stat3 transcription factor without
involvement of the extracellular Ang II
signaling pathway.
Collapse
|
10
|
New insights into the renoprotective actions of the renin inhibitor aliskiren in experimental renal disease. Hypertens Res 2010; 33:279-87. [PMID: 20203685 DOI: 10.1038/hr.2010.19] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The renin-angiotensin-aldosterone system (RAAS) has a central function in the regulation of blood pressure. Aliskiren, the first direct renin inhibitor to be approved for the treatment of hypertension, blocks the RAAS at its point of activation. As renin inhibition acts at the top of the RAAS cascade, this mechanism has been proposed to offer advantages over existing modes of RAAS blockade. The RAAS is also considered to be a major factor in the pathogenesis of many renal diseases, especially diabetic nephropathy (DN), the main cause of end-stage renal disease. Existing therapies to block the RAAS slow the progression of DN, but they do not halt the disease. Therefore, more effective modes of interventions are needed. Studies to determine the efficacy of aliskiren in human renal disease are in progress. This review summarizes in vivo studies in which the efficacy of aliskiren was tested in experimental models of renal disease, and presents in vitro studies that provide insights into the possible mechanisms by which aliskiren confers renoprotection in animals. These works are discussed in the framework of the intrarenal RAAS and suggest that aliskiren may act by unique renoprotective mechanisms.
Collapse
|
11
|
Feliers D, Kasinath BS. Mechanism of VEGF expression by high glucose in proximal tubule epithelial cells. Mol Cell Endocrinol 2010; 314:136-42. [PMID: 19765632 PMCID: PMC2783935 DOI: 10.1016/j.mce.2009.09.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 08/31/2009] [Accepted: 09/09/2009] [Indexed: 01/13/2023]
Abstract
Angiotensin II (Ang II) and vascular endothelial growth factor (VEGF) are important mediators of kidney injury in diabetes. VEGF expression is increased in proximal tubules of mice with type 1 diabetes. In mouse proximal tubular epithelial cells (MCT) cultured with 30 mM glucose (HG) for 24h, VEGF expression is increased at the protein and the mRNA level, suggesting a transcriptional mechanism. HG stimulation of VEGF synthesis is prevented by captopril, an inhibitor of angiotensin-converting enzyme, and, by losartan, a specific antagonist of angiotensin type 1 receptor (AT1), suggesting that VEGF synthesis is mediated by Ang II. Synthesis of angiotensinogen (AGT), a precursor of angiotensin II, is increased in MCTs cultured in HG. Although synthesis of renin and ACE is not affected by HG, their activity is increased in the conditioned medium. Concentrations of Ang I and Ang II are also increased in conditioned medium from HG-treated MCTs and captopril prevents increased Ang II, but not Ang I, synthesis. Finally, AT1 is activated in MCTs treated with HG, and its activation is prevented by captopril and losartan. The ERK pathway is activated by HG within minutes of stimulation and lasting for up to 24h. The initial phase of ERK activation is due to HG itself and leads to AGT upregulation and the sustained phase is mediated for the most part by Ang II-activated AT1 receptor and leads to increased VEGF synthesis. These data show that: (1) HG increases AGT synthesis and activation of renin and ACE by MCTs, leading to local production of Ang I and Ang II. (2) Ang II activates endogenous AT1 and stimulates synthesis of VEGF. (3) HG activation of ERK starts within minutes and lasts for up to 24h. Early ERK activation is involved in AGT upregulation and sustained ERK activation, mediated via AT1, is responsible for VEGF synthesis. In conclusion, our study shows that MCTs express an endogenous renin-angiotensin system that is activated by high glucose to stimulate the synthesis of VEGF, through activation of the ERK pathway.
Collapse
Affiliation(s)
- Denis Feliers
- O'Brien Kidney Research Center, Department of Medicine/Nephrology, University of Texas Health Science Center, San Antonio, TX 78229, USA.
| | | |
Collapse
|
12
|
Inhibition of intracellular angiotensin II formation blocks high glucose effect on mesangial matrix. ACTA ACUST UNITED AC 2009; 158:103-9. [PMID: 19712706 DOI: 10.1016/j.regpep.2009.08.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 08/03/2009] [Accepted: 08/16/2009] [Indexed: 11/21/2022]
Abstract
High glucose causes increased matrix synthesis by glomerular mesangial cells and angiotensin II (Ang II) has been shown to mediate this effect of glucose. These studies investigate whether inhibition of Ang II formation can block high glucose-induced increase in mesangial matrix. Human mesangial cells were incubated with 25 mM glucose (HG) along with captopril, an ACE inhibitor, to block Ang II formation. In other experiments, cells were nucleofected with siRNA to knockdown angiotensinogen (Agt), the precursor of Ang II, and then exposed to high glucose. Captopril blocked high glucose-induced increase in Ang II levels in the cell media (extracellular) but failed to inhibit it in the cell lysate (intracellular). Moreover, captopril treatment did not block the stimulatory effect of high glucose on TGF-beta1 and fibronectin. In contrast, knockdown of the Agt gene prevented high glucose-induced increase in both extracellular and intracellular Ang II levels, and was accompanied by normalization of TGF-beta1 and fibronectin. These data suggest that intracellular Ang II may play an important role in the mediation of the high glucose effect on matrix and that ACE inhibitors may not be effective in blocking intracellular Ang II formation in mesangial cells.
Collapse
|
13
|
Abstract
PURPOSE OF REVIEW The renin-angiotensin system (RAS) has undergone continuous advancement since the initial identification of renin as a pressor agent. Traditionally considered a circulatory system, the RAS is now known to exist as a tissue system as well. Recently, the tissue RAS has been further categorized as intracellular and extracellular. Owing to the unique location, the intracellular RAS encompasses new components, such as cathepsin D and chymase, which participate in intracellular angiotensin (Ang) II synthesis. In this review, evidence of the intracellular RAS and the mechanism of Ang II synthesis in various cell types will be discussed. RECENT FINDINGS A physiological role for intracellular Ang II in vascular and cardiac cells has recently been demonstrated. Evidence of intracellular Ang II generation has been shown in several cell types, particularly cardiac, renal, and vascular. Importantly, intracellular synthesis of Ang II is more prominent in hyperglycemic conditions and generally involves angiotensin-converting enzyme-dependent and angiotensin-converting enzyme-independent mechanisms. SUMMARY There is significant diversity in the mechanism of intracellular synthesis of Ang II in various cell types and pathological conditions. These observations suggest that a therapeutic intervention to block the RAS should take into consideration the nature of the disorder and the cell type involved.
Collapse
|
14
|
|
15
|
Current World Literature. Curr Opin Nephrol Hypertens 2009; 18:91-3. [DOI: 10.1097/mnh.0b013e32831fd875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
16
|
Singh VP, Le B, Khode R, Baker KM, Kumar R. Intracellular angiotensin II production in diabetic rats is correlated with cardiomyocyte apoptosis, oxidative stress, and cardiac fibrosis. Diabetes 2008; 57:3297-306. [PMID: 18829990 PMCID: PMC2584136 DOI: 10.2337/db08-0805] [Citation(s) in RCA: 253] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Accepted: 09/08/2008] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Many of the effects of angiotensin (Ang) II are mediated through specific plasma membrane receptors. However, Ang II also elicits biological effects from the interior of the cell (intracrine), some of which are not inhibited by Ang receptor blockers (ARBs). Recent in vitro studies have identified high glucose as a potent stimulus for the intracellular synthesis of Ang II, the production of which is mainly chymase dependent. In the present study, we determined whether hyperglycemia activates the cardiac intracellular renin-Ang system (RAS) in vivo and whether ARBs, ACE, or renin inhibitors block synthesis and effects of intracellular Ang II (iAng II). RESEARCH DESIGN AND METHODS Diabetes was induced in adult male rats by streptozotocin. Diabetic rats were treated with insulin, candesartan (ARB), benazepril (ACE inhibitor), or aliskiren (renin inhibitor). RESULTS One week of diabetes significantly increased iAng II levels in cardiac myocytes, which were not normalized by candesartan, suggesting that Ang II was synthesized intracellularly, not internalized through AT(1) receptor. Increased intracellular levels of Ang II, angiotensinogen, and renin were observed by confocal microscopy. iAng II synthesis was blocked by aliskiren but not by benazepril. Diabetes-induced superoxide production and cardiac fibrosis were partially inhibited by candesartan and benazepril, whereas aliskiren produced complete inhibition. Myocyte apoptosis was partially inhibited by all three agents. CONCLUSIONS Diabetes activates the cardiac intracellular RAS, which increases oxidative stress and cardiac fibrosis. Renin inhibition has a more pronounced effect than ARBs and ACE inhibitors on these diabetes complications and may be clinically more efficacious.
Collapse
Affiliation(s)
- Vivek P. Singh
- Division of Molecular Cardiology, Department of Medicine, Texas A&M Health Science Center, College of Medicine, Scott & White, Central Texas Veterans Health Care System, Temple, Texas
- Department of Medicine, Scott & White, Temple, Texas
| | - Bao Le
- Department of Medicine, Scott & White, Temple, Texas
| | - Renu Khode
- Department of Pathology, Scott & White, Temple, Texas
| | - Kenneth M. Baker
- Division of Molecular Cardiology, Department of Medicine, Texas A&M Health Science Center, College of Medicine, Scott & White, Central Texas Veterans Health Care System, Temple, Texas
- Department of Medicine, Scott & White, Temple, Texas
| | - Rajesh Kumar
- Division of Molecular Cardiology, Department of Medicine, Texas A&M Health Science Center, College of Medicine, Scott & White, Central Texas Veterans Health Care System, Temple, Texas
- Department of Medicine, Scott & White, Temple, Texas
| |
Collapse
|
17
|
The intracellular renin-angiotensin system: implications in cardiovascular remodeling. Curr Opin Nephrol Hypertens 2008; 17:168-73. [PMID: 18277150 DOI: 10.1097/mnh.0b013e3282f521a8] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW The renin-angiotensin system, traditionally viewed as a circulatory system, has significantly expanded in the last two decades to include independently regulated local systems in several tissues, newly identified active products of angiotensin II, and new receptors and functions of renin-angiotensin system components. In spite of our increased understanding of the renin-angiotensin system, a role of angiotensin II in cardiac hypertrophy, through direct effects on cardiovascular tissue, is still being debated. Here, we address the cardiovascular effects of angiotensin II and the role an intracellular renin-angiotensin system might play. RECENT FINDINGS Recent studies have shown that cardiac myocytes, fibroblasts and vascular smooth muscle cells synthesize angiotensin II intracellularly. Some conditions, such as high glucose, selectively increase intracellular generation and translocation of angiotensin II to the nucleus. Intracellular angiotensin II regulates the expression of angiotensinogen and renin, generating a feedback loop. The first reaction of intracellular angiotensin II synthesis is catalyzed by renin or cathepsin D, depending on the cell type, and chymase, not angiotensin-converting enzyme, catalyzes the second step. SUMMARY These studies suggest that the intracellular renin-angiotensin system is an important component of the local system. Alternative mechanisms of angiotensin II synthesis and action suggest a need for novel therapeutic agents to block the intracellular renin-angiotensin system.
Collapse
|
18
|
Cristovam PC, Arnoni CP, de Andrade MCC, Casarini DE, Pereira LG, Schor N, Boim MA. ACE-dependent and chymase-dependent angiotensin II generation in normal and glucose-stimulated human mesangial cells. Exp Biol Med (Maywood) 2008; 233:1035-43. [PMID: 18480420 DOI: 10.3181/0708-rm-229] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
High glucose (HG) increases angiotensin II (AngII) generation in mesangial cells (MC). Chymase, an alternative AngII-generating enzyme, is upregulated in the glomeruli of diabetic kidneys. In this study, we examined AngII synthesis by human MC via angiotensin-converting enzyme (ACE)-dependent and chymase-dependent pathways under normal glucose (NG, 5 mM) and HG (30 mM) conditions. NG cells expressed ACE and chymase mRNA. Under NG conditions the chymase inhibitor chymostatin reduced AngII levels in cell lysates and in the culture medium, and the ACE inhibitor captopril had no effect. HG induced a 3-fold increase in chymase mRNA and protein but not in ACE mRNA; however, HG induced a 10-fold increase in intracellular ACE activity. The increase in AngII generation induced by HG was found in the cell lysate but not in the culture medium. The rise in intracellular AngII was not prevented by captopril or by chymostatin. Moreover, captopril inhibited extracellular ACE activity but failed to block intracellular ACE activity; these results suggested that captopril was unable to reach intra-cellular ACE. Losartan did not change the intracellular AngII content in either NG or HG conditions, and this lack of change suggested that the increase in AngII was due to intracellular generation. Together these results suggest that chymase may be active in human MC and that both ACE and chymase are involved in increased AngII generation during the HG stimulus by different mechanisms, including an upregulation of chymase mRNA and a rise in intracellular ACE activity, favoring the generation and accumulation of intracellular AngII.
Collapse
Affiliation(s)
- Priscila C Cristovam
- Department of Medicine-Renal Division, Federal University of São Paulo, São Paulo, Brazil
| | | | | | | | | | | | | |
Collapse
|
19
|
Silva CA, Portaro FC, Fernandes BL, Ianzer DA, Guerreiro JR, Gomes CL, Konno K, Serrano SM, Nascimento N, Camargo AC. Tissue distribution in mice of BPP 10c, a potent proline-rich anti-hypertensive peptide of Bothrops jararaca. Toxicon 2008; 51:515-23. [DOI: 10.1016/j.toxicon.2007.11.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Revised: 11/01/2007] [Accepted: 11/05/2007] [Indexed: 10/22/2022]
|
20
|
Singh VP, Baker KM, Kumar R. Activation of the intracellular renin-angiotensin system in cardiac fibroblasts by high glucose: role in extracellular matrix production. Am J Physiol Heart Circ Physiol 2008; 294:H1675-84. [PMID: 18296558 DOI: 10.1152/ajpheart.91493.2007] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The occurrence of a functional intracellular renin-angiotensin system (RAS) has emerged as a new paradigm. Recently, we and others demonstrated intracellular synthesis of ANG II in cardiac myocytes and vascular smooth muscle cells that was dramatically stimulated in high glucose conditions. Cardiac fibroblasts significantly contribute to diabetes-induced diastolic dysfunction. The objective of the present study was to determine the existence of the intracellular RAS in cardiac fibroblasts and its role in extracellular matrix deposition. Neonatal rat ventricular fibroblasts were serum starved and exposed to isoproterenol or high glucose in the absence or presence of candesartan, which was used to prevent receptor-mediated uptake of ANG II. Under these conditions, an increase in ANG II levels in the cell lysate represented intracellular synthesis. Both isoproterenol and high glucose significantly increased intracellular ANG II levels. Confocal microscopy revealed perinuclear and nuclear distribution of intracellular ANG II. Consistent with intracellular synthesis, Western analysis showed increased intracellular levels of renin following stimulation with isoproterenol and high glucose. ANG II synthesis was catalyzed by renin and angiotensin-converting enzyme (ACE), but not chymase, as determined using specific inhibitors. High glucose resulted in increased transforming growth factor-beta and collagen-1 synthesis by cardiac fibroblasts that was partially inhibited by candesartan but completely prevented by renin and ACE inhibitors. In conclusion, cardiac fibroblasts contain a functional intracellular RAS that participates in extracellular matrix formation in high glucose conditions, an observation that may be helpful in developing an appropriate therapeutic strategy in diabetic conditions.
Collapse
Affiliation(s)
- Vivek P Singh
- Cardiovascular Research Institute, Texas A&M HSC, Temple, TX 76504, USA
| | | | | |
Collapse
|