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Hall S, Ward ND, Patel R, Amin-Javaheri A, Lanford H, Grespin RT, Couch C, Xiong Y, Mukherjee R, Jones JA, Ruddy JM. Mechanical activation of the angiotensin II type 1 receptor contributes to abdominal aortic aneurysm formation. JVS Vasc Sci 2021; 2:194-206. [PMID: 34761239 PMCID: PMC8567200 DOI: 10.1016/j.jvssci.2021.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 07/14/2021] [Indexed: 12/22/2022] Open
Abstract
Objective The angiotensin II type 1 receptor (AT1R) can be activated under conditions of mechanical stretch in some cellular systems. Whether this activity influences signaling within the abdominal aorta to promote to abdominal aortic aneurysm (AAA) development remains unknown. We evaluated the hypothesis that mechanical AT1R activation can occur under conditions of hypertension (HTN) and contribute to AAA formation. Methods BPH/2 mice, which demonstrate spontaneous neurogenic, low-renin HTN, and normotensive BPN/3 mice underwent AAA induction via the calcium chloride model, with or without an osmotic minipump delivering 30 mg/kg/d of the AT1R blocker Losartan. Systolic blood pressure (SBP) was measured at baseline and weekly via a tail cuff. The aortic diameter (AoD) was measured at baseline and terminal surgery at 21 days by digital microscopy. Aortic tissue was harvested for immunoblotting (phosphorylated extracellular signal-regulated kinase-1 and -2 [pERK1/2] to ERK1/2 ratio) and expressed as the fold-change from the BPN/3 control mice. Aortic vascular smooth muscle cells (VSMCs) underwent stretch with or without Losartan (1 μM) treatment to assess the mechanical stimulation of ERK1/2 activity. Statistical analysis of the blood pressure, AoD, and VSMC ERK1/2 activity was performed using analysis of variance. However, the data distribution was determined to be log-normal (Shapiro-Wilk test) for ERK1/2 activity. Therefore, it was logarithmically transformed before analysis of variance. Results At baseline, the SBP was elevated in the BPH/2 mice relative to the BPN/3 mice (P < .05). Losartan treatment significantly reduced the SBP in both mouse strains (P < .05). AAA induction did not affect the SBP. At 21 days after induction, the percentage of increase in the AoD from baseline was significantly greater in the BPH/2 mice than in the BPN/3 mice (101.28% ± 4.19% vs 75.59% ± 1.67% above baseline; P < .05). Losartan treatment significantly attenuated AAA growth in both BPH/2 and BPN/3 mice (33.88% ± 2.97% and 43.96% ± 3.05% above baseline, respectively; P < .05). ERK1/2 activity was increased approximately fivefold in the BPH/2 control mice relative to the BPN/3 control mice (P < .05). In the BPH/2 and BPN/3 mice with AAA, ERK1/2 activity was significantly increased relative to the respective baseline control (P < .05) and effectively reduced by concomitant Losartan therapy (P < .05). Biaxial stretch of the VSMCs in the absence of angiotensin II demonstrated increased ERK1/2 activation (P < .05 vs static control), which was significantly inhibited by Losartan. Conclusions In BPH/2 mice with spontaneous neurogenic, low-renin HTN, AAA growth was amplified compared with the normotensive control and was effectively attenuated using Losartan. ERK1/2 activity was significantly elevated in the BPH/2 mice and after AAA induction in the normotensive and hypertensive mice but was attenuated by Losartan treatment. These data suggest that AT1R activation contributes to AAA development. Therefore, further investigation into this signaling pathway could establish targets for pharmacotherapeutic engineering to slow AAA growth. (JVS-Vascular Science 2021;2:194-206.). Clinical Relevance Hypertension (HTN) and abdominal aortic aneurysm (AAA) have been epidemiologically linked for decades; however, a biomechanical link has not yet been identified. Using a murine model of spontaneous neurogenic HTN experimentally demonstrated to have low circulating renin, mechanical activation of the angiotensin II type 1 receptor (AT1R) was identified with elevated blood pressure and AAA induction. HTN amplified AAA growth. However, more importantly, blocking the activation of AT1R with the angiotensin receptor blocker Losartan effectively abrogated AAA development. Although inhibiting the production of angiotensin II has previously been unsuccessful in altering AAA growth, the results from the present study suggest that blocking the activation of AT1R through direct ligand binding or mechanical stimulation might alter aortic wall signaling and warrants further investigation.
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Affiliation(s)
- SarahRose Hall
- Division of Vascular Surgery, Medical University of South Carolina, Charleston, SC
| | - Nicholas D Ward
- Division of Vascular Surgery, Medical University of South Carolina, Charleston, SC
| | - Raj Patel
- Division of Vascular Surgery, Medical University of South Carolina, Charleston, SC
| | - Armaan Amin-Javaheri
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC
| | - Hayes Lanford
- Division of Vascular Surgery, Medical University of South Carolina, Charleston, SC
| | - R Tyler Grespin
- Division of Vascular Surgery, Medical University of South Carolina, Charleston, SC
| | - Christine Couch
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC
| | - Ying Xiong
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC
| | - Rupak Mukherjee
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC.,Ralph H. Johnson VA Medical Center, Charleston, SC
| | - Jeffrey A Jones
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC.,Ralph H. Johnson VA Medical Center, Charleston, SC
| | - Jean Marie Ruddy
- Division of Vascular Surgery, Medical University of South Carolina, Charleston, SC.,Ralph H. Johnson VA Medical Center, Charleston, SC
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Akerman AW, Blanding WM, Stroud RE, Nadeau EK, Mukherjee R, Ruddy JM, Zile MR, Ikonomidis JS, Jones JA. Elevated Wall Tension Leads to Reduced miR-133a in the Thoracic Aorta by Exosome Release. J Am Heart Assoc 2020; 8:e010332. [PMID: 30572760 PMCID: PMC6405702 DOI: 10.1161/jaha.118.010332] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Background Reduced miR‐133a was previously found to be associated with thoracic aortic (TA) dilation, as seen in aneurysm disease. Because wall tension increases with vessel diameter (Law of Laplace), this study tested the hypothesis that elevated tension led to the reduction of miR‐133a in the TA. Methods and Results Elevated tension (1.5 g; 150 mm Hg) applied to murine TA ex vivo reduced miR‐133a tissue abundance compared with TA held at normotension (0.7 g; 70 mm Hg). Cellular miR‐133a levels were reduced with biaxial stretch of isolated murine TA fibroblasts, whereas smooth muscle cells were not affected. Mechanisms contributing to the loss of miR‐133a abundance were further investigated in TA fibroblasts. Biaxial stretch did not reduce primary miR‐133a transcription and had no effect on the expression/abundance of 3 microRNA‐specific exoribonucleases. Remarkably, biaxial stretch increased exosome secretion, and exosomes isolated from TA fibroblasts contained more miR‐133a. Inhibition of exosome secretion prevented the biaxial stretch‐induced reduction of miR‐133a. Subsequently, 2 in vivo models of hypertension were used to determine the effect of elevated wall tension on miR‐133a abundance in the TA: wild‐type mice with osmotic pump–mediated angiotensin II infusion and angiotensin II–independent spontaneously hypertensive mice. Interestingly, the abundance of miR‐133a was decreased in TA tissue and increased in the plasma in both models of hypertension compared with a normotensive control group. Furthermore, miR‐133a was elevated in the plasma of hypertensive human subjects, compared with normotensive patients. Conclusions Taken together, these results identified exosome secretion as a tension‐sensitive mechanism by which miR‐133a abundance was reduced in TA fibroblasts.
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Affiliation(s)
- Adam W Akerman
- 1 Division of Cardiothoracic Surgery Department of Surgery Medical University of South Carolina Charleston SC.,4 Cardiothoracic Surgery Research University of North Carolina at Chapel Hill NC
| | - Walker M Blanding
- 1 Division of Cardiothoracic Surgery Department of Surgery Medical University of South Carolina Charleston SC
| | - Robert E Stroud
- 1 Division of Cardiothoracic Surgery Department of Surgery Medical University of South Carolina Charleston SC
| | - Elizabeth K Nadeau
- 1 Division of Cardiothoracic Surgery Department of Surgery Medical University of South Carolina Charleston SC
| | - Rupak Mukherjee
- 1 Division of Cardiothoracic Surgery Department of Surgery Medical University of South Carolina Charleston SC.,2 Research Service Ralph H. Johnson Veterans Affairs Medical Center Charleston SC
| | - Jean Marie Ruddy
- 3 Division of Vascular Surgery Medical University of South Carolina Charleston SC
| | - Michael R Zile
- 1 Division of Cardiothoracic Surgery Department of Surgery Medical University of South Carolina Charleston SC.,2 Research Service Ralph H. Johnson Veterans Affairs Medical Center Charleston SC
| | - John S Ikonomidis
- 4 Cardiothoracic Surgery Research University of North Carolina at Chapel Hill NC
| | - Jeffrey A Jones
- 1 Division of Cardiothoracic Surgery Department of Surgery Medical University of South Carolina Charleston SC.,2 Research Service Ralph H. Johnson Veterans Affairs Medical Center Charleston SC
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Jackson KL, Head GA, Gueguen C, Stevenson ER, Lim K, Marques FZ. Mechanisms Responsible for Genetic Hypertension in Schlager BPH/2 Mice. Front Physiol 2019; 10:1311. [PMID: 31681017 PMCID: PMC6813185 DOI: 10.3389/fphys.2019.01311] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 09/30/2019] [Indexed: 01/18/2023] Open
Abstract
It has been 45 years since Gunther Schlager used a cross breeding program in mice to develop inbred strains with high, normal, and low blood pressure (BPH/2, BPN/3, and BPL/1 respectively). Thus, it is timely to gather together the studies that have characterized and explored the mechanisms associated with the hypertension to take stock of exactly what is known and what remains to be determined. Growing evidence supports the notion that the mechanism of hypertension in BPH/2 mice is predominantly neurogenic with some of the early studies showing aberrant brain noradrenaline levels in BPH/2 compared with BPN/3. Analysis of the adrenal gland using microarray suggested an association with the activity of the sympathetic nervous system. Indeed, in support of this, there is a larger depressor response to ganglion blockade, which reduced blood pressure in BPH/2 mice to the same level as BPN/3 mice. Greater renal tyrosine hydroxylase staining and greater renal noradrenaline levels in BPH/2 mice suggest sympathetic hyperinnervation of the kidney. Renal denervation markedly reduced the blood pressure in BPH/2 but not BPN/3 mice, confirming the importance of renal sympathetic nervous activity contributing to the hypertension. Further, there is an important contribution to the hypertension from miR-181a and renal renin in this strain. BPH/2 mice also display greater neuronal activity of amygdalo-hypothalamic cardiovascular regulatory regions. Lesions of the medial nucleus of the amygdala reduced the hypertension in BPH/2 mice and abolished the strain difference in the effect of ganglion blockade, suggesting a sympathetic mechanism. Further studies suggest that aberrant GABAergic inhibition may play a role since BPH/2 mice have low GABAA receptor δ, α4 and β2 subunit mRNA expression in the hypothalamus, which are predominantly involved in promoting tonic neuronal inhibition. Allopregnanolone, an allosteric modulator of GABAA receptors, which increase the expression of these subunits in the amygdala and hypothalamus, is shown to reduce the hypertension and sympathetic nervous system contribution in BPH/2 mice. Thus far, evidence suggests that BPH/2 mice have aberrant GABAergic inhibition, which drives neuronal overactivity within amygdalo-hypothalamic brain regions. This overactivity is responsible for the greater sympathetic contribution to the hypertension in BPH/2 mice, thus making this an ideal model of neurogenic hypertension.
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Affiliation(s)
- Kristy L Jackson
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Geoffrey A Head
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Cindy Gueguen
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Emily R Stevenson
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Kyungjoon Lim
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Melbourne, VIC, Australia
| | - Francine Z Marques
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Hypertension Research Laboratory, School of Biological Sciences, Monash University, Clayton, VIC, Australia
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Zhang Z, Zhao J, Tian C, Chen X, Li H, Wei X, Lin W, Zheng N, Jiang A, Feng R, Yuan J, Zhao X. Targeting the Gut Microbiota to Investigate the Mechanism of Lactulose in Negating the Effects of a High-Salt Diet on Hypertension. Mol Nutr Food Res 2019; 63:e1800941. [PMID: 30825362 DOI: 10.1002/mnfr.201800941] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 02/25/2019] [Indexed: 12/15/2022]
Abstract
SCOPE High-salt diets (HSDs) are widely considered to cause health problems such as gut microecological imbalances, constipation, and hypertension. This study explores how lactulose as a safe molecule can stimulate bodily responses to alleviate salt-sensitive hypertension by regulating the gut microbiotas of HSD-fed mice. METHODS AND RESULTS After 4 weeks, the blood pressures of mice fed a high-salt plus lactulose diet (HSLD) are significantly lower than those of the HSD-fed mice. The HSD increases the abundances of Alistipes and Ruminococcaceae_UCG_009 and reduced the abundance of Lactobacillus in the gut, while lactulose supplementation increases the abundances of Bifidobacterium, Alloprevotella, and Subdoligranulum. Fecal metabolic profiling shows significant increases in metabolites involved in ATP-binding cassette transporter pathways, and tryptophan metabolism is significantly reduced in the HSLD group compared with the HSD group. Lactulose maintains the intestinal microenvironmental health in the HSD-fed mice by improving glycolipid metabolism, decreasing the small intestinal interleukin-17a (IL-17a) and interleukin-22 (IL-22) mRNA levels and serum IL-17a and IL-22 levels, relieving constipation, increasing fecal sodium, and reducing intestinal permeability. CONCLUSION Lactulose negates salt-sensitive hypertension. Regulating the gut microbiota is a potential treatment for salt-sensitive hypertension.
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Affiliation(s)
- Zheng Zhang
- College of Food Science, South China Agricultural University, Guangzhou, 510000, China
| | - Jiangtao Zhao
- Department of Histology and Embryology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Changyu Tian
- Institute of Disease Control and Prevention, China PLA, Beijing, 100071, China
| | - Xiao Chen
- College of Food Science, South China Agricultural University, Guangzhou, 510000, China
| | - Huan Li
- Institute of Disease Control and Prevention, China PLA, Beijing, 100071, China
| | - Xiao Wei
- Institute of Disease Control and Prevention, China PLA, Beijing, 100071, China
| | - Weishi Lin
- Institute of Disease Control and Prevention, China PLA, Beijing, 100071, China
| | - Naxin Zheng
- Department of Laboratory Medicine, Fifth Medical Center of PLA General Hospital, Beijing, 100071, China
| | - Aimin Jiang
- College of Food Science, South China Agricultural University, Guangzhou, 510000, China
| | - Ruo Feng
- Department of Histology and Embryology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Jing Yuan
- Institute of Disease Control and Prevention, China PLA, Beijing, 100071, China
| | - Xiangna Zhao
- Institute of Disease Control and Prevention, China PLA, Beijing, 100071, China
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Jackson KL, Marques FZ, Watson AMD, Palma-Rigo K, Nguyen-Huu TP, Morris BJ, Charchar FJ, Davern PJ, Head GA. A novel interaction between sympathetic overactivity and aberrant regulation of renin by miR-181a in BPH/2J genetically hypertensive mice. Hypertension 2013; 62:775-81. [PMID: 23897069 DOI: 10.1161/hypertensionaha.113.01701] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Genetically hypertensive mice (BPH/2J) are hypertensive because of an exaggerated contribution of the sympathetic nervous system to blood pressure. We hypothesize that an additional contribution to elevated blood pressure is via sympathetically mediated activation of the intrarenal renin-angiotensin system. Our aim was to determine the contribution of the renin-angiotensin system and sympathetic nervous system to hypertension in BPH/2J mice. BPH/2J and normotensive BPN/3J mice were preimplanted with radiotelemetry devices to measure blood pressure. Depressor responses to ganglion blocker pentolinium (5 mg/kg i.p.) in mice pretreated with the angiotensin-converting enzyme inhibitor enalaprilat (1.5 mg/kg i.p.) revealed a 2-fold greater sympathetic contribution to blood pressure in BPH/2J mice during the active and inactive period. However, the depressor response to enalaprilat was 4-fold greater in BPH/2J compared with BPN/3J mice, but only during the active period (P=0.01). This was associated with 1.6-fold higher renal renin messenger RNA (mRNA; P=0.02) and 0.8-fold lower abundance of micro-RNA-181a (P=0.03), identified previously as regulating human renin mRNA. Renin mRNA levels correlated positively with depressor responses to pentolinium (r=0.99; P=0.001), and BPH/2J mice had greater renal sympathetic innervation density as identified by tyrosine hydroxylase staining of cortical tubules. Although there is a major sympathetic contribution to hypertension in BPH/2J mice, the renin-angiotensin system also contributes, doing so to a greater extent during the active period and less during the inactive period. This is the opposite of the normal renin-angiotensin system circadian pattern. We suggest that renal hyperinnervation and enhanced sympathetically induced renin synthesis mediated by lower micro-RNA-181a contributes to hypertension in BPH/2J mice.
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Affiliation(s)
- Kristy L Jackson
- Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Research Institute, P.O. Box 6492, St Kilda Rd Central, Melbourne, Victoria 8008, Australia.
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Renin-angiotensin and sympathetic nervous system contribution to high blood pressure in Schlager mice. J Hypertens 2012; 29:2156-66. [PMID: 21941207 DOI: 10.1097/hjh.0b013e32834bbb6b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Schlager hypertensive (BPH/2J) mice have been suggested to have high blood pressure (BP) due to an overactive sympathetic nervous system (SNS), but the contribution of the renin-angiotensin system (RAS) is unclear. In the present study, we examined the cardiovascular effects of chronically blocking the RAS in BPH/2J mice. METHODS Schlager normotensive (BPN/3J, n = 6) and BPH/2J mice (n = 8) received the angiotensin AT 1A-receptor antagonist losartan (150 mg/kg per day) in drinking water for 2 weeks. Pre-implanted telemetry devices were used to record mean arterial pressure (MAP), heart rate (HR) and locomotor activity. RESULTS MAP was reduced by losartan treatment in BPN/3J (-23 mmHg, P < 0.01) and in BPH/2J mice (-25 mmHg, P < 0.001), whereas HR was increased. Losartan had little effect on initial pressor responses to feeding or to stress, but did attenuate the sustained pressor response to cage-switch stress. During the active period, the hypotension to sympathetic blockade with pentolinium was greater in BPH/2J than BPN/3J (suggesting neurogenic hypertension), but was not affected by losartan. During the inactive period, a greater depressor response to pentolinium was observed in losartan-treated animals. CONCLUSION The hypotensive actions of losartan suggest that although the RAS provides an important contribution to BP, it contributes little, if at all, to the hypertension-induced or the greater stress-induced pressor responses in Schlager mice. The effects of pentolinium suggest that the SNS is mainly responsible for hypertension in BPH/2J mice. However, the RAS inhibits sympathetic vasomotor tone during inactivity and prolongs sympathetic activation during periods of adverse stress, indicating an important sympatho-modulatory role.
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