Single Nucleotide Variants in the Angiotensin II Receptor Type 2 and its Association With Arterial Hypertension: A Systematic Review

Abstract Background: Arterial hypertension (AH) is a chronic disease distributed worldwide, and the Angiotensin II receptor type 2 (AGTR2) gene variants are potential DNA markers to study in association with this disease. Objective: This systematic review (SR) aimed to identify single nucleotide variants in the AGTR2 gene as genetic markers associated with AH. Methods: The electronic databases MEDLINE, Web of Science, SCOPUS, Cochrane Central Register, EMBASE, SciELO, and TripDatabase were searched for research up to September 2023. Case-control studies with DNA variants in the AGTR2 gene associated with AH as the outcome were included in the review. Boolean connectors and keywords were used according to each database. Results: After diverse rounds of scrutiny, a final number of eight articles were included for 8911 participants, comprising 5451 cases and 3460 controls. A significant proportion of the selected studies were performed in Asian populations and were heterogeneous. Although 238 variants were shown in the gnomAD v2.1.1 database for September 2023, only six variants were identified in all the analyzed studies. Conclusions: The results obtained were not conclusive that a specific variant located in the AGTR2 gene has a strong association with AH. The study of this gene re-emerged last year as an essential target to investigate due to its participation in the development of agonist therapy to treat mild COVID-19 cases. Future studies with better statistical power are desirable to replicate the primary findings.

Effects of different doses of dexamethasone on angiotensin II, its receptors and NO levels in septic kidney injury rats / 中国临床药理学与治疗学

AIM: To investigate the changes of angiotensin II, its receptors and nitric oxide (NO) expression in rats with acute kidney injury (AKI) induced by endotoxin (LPS) and to assess the efficacy of different doses of dexamethasone (DXM). METHODS: Wistar rats were randomly divided into five groups as follows: control group (NC), LPS group, and DXM treatment groups of different doses of DXM (0.5, 1.0 and 5.0 mg/kg). The AKI group was injected with LPS through the lateral tail vein, and the intervention group was given different doses of DXM after LPS injection. Tissue samples were collected at 2, 6, 12 and 24 h after treatment. Serum creatinine and urea nitrogen levels were determined by automatic biochemical analyzer. H&E staining was used to observe renal histopathology. Serum TNF-α and MIP-1α levels were determined by ELISA. The expression of the angiotensin receptor 1 (AT1R) and angiotensin receptor 2 (AT2R) proteins were detected by Western blot and immunohistochemistry. Nitrate reductase was used to detect NO changes in the serum and renal tissues. RESULTS: The serum levels of serum TNF-α, MIP-1α, creatinine, and urea nitrogen were significantly increased in the LPS group compared with the control group (P<0.05). A similar trend was also observed in the levels of plasma and renal tissue AngII, renal tissue AT2R, serum and renal tissue NO (P<0.05). The expression of AT1R in renal tissue was significantly decreased in the LPS group compared with the control group (P<0.05). Pathological analysis showed that glomerular neutrophil infiltration and renal tubular epithelial cells swelling, vacuolar degeneration and necrosis in the LPS group. Prolongation LPS treatment resulted in more significant kidney damage. The serum levels of TNF-α, MIP-1α, creatinine, and urea nitrogen were significantly decreased in the DXM group compared with the LPS group (P<0.05). A similar trend was also observed in the levels of plasma and renal tissue AngII, renal tissue AT2R, serum and renal tissue NO in the DXM group (P<0.05). The expression of AT1R in renal tissue was significantly increased (P<0.05) in the DXM group compared with the LPS group, indicating the alleviation of kidney injury. Amongst these biomarkers, the levels of serum TNF-α, MIP-1α, plasma AngII showed the most significant decrease in the high dose DMX group (P<0.05). The levels of serum creatinine, urea nitrogen, kidney NO showed more significant decreases in the low and medium dose DMX groups (P<0.05). The levels of kidney AngII to dose and AT1R showed the most significant decrease in medium and high dose DXM groups (P<0.05). The levels of kidney AT2R and serum NO were not significantly different between the DXM treatment groups. CONCLUSION: LPS can induce AKI in rats that can be mitigated by DXM. The mechanism of DXM in protection against AKI may be related to the down-regulation of inflammatory factors such as AngII, AT2R, and NO, and the up-regulation of AT1R expression. Different doses of dexamethasone have different intervention effects for different effector molecules.

Angiotensin-(1-9) ameliorates pulmonary arterial hypertension via angiotensin type II receptor

Angiotensin-(1-9) [Ang-(1-9)], generated from Ang I by Ang II converting enzyme 2, has been reported to have protective effects on cardiac and vascular remodeling. However, there is no report about the effect of Ang-(1-9) on pulmonary hypertension. The aim of the present study is to investigate whether Ang-(1-9) improves pulmonary vascular remodeling in monocrotaline (MCT)-induced pulmonary hypertensive rats. Sprague-Dawley rats received Ang-(1-9) (576 µg/kg/day) or saline via osmotic mini-pumps for 3 weeks. Three days after implantation of osmotic mini-pumps, 50 mg/kg MCT or vehicle were subcutaneously injected. MCT caused increases in right ventricular weight and systolic pressure, which were reduced by co-administration of Ang-(1-9). Ang-(1-9) also attenuated endothelial damage and medial hypertrophy of pulmonary arterioles as well as pulmonary fibrosis induced by MCT. The protective effects of Ang-(1-9) against pulmonary hypertension were inhibited by Ang type 2 receptor (AT₂R) blocker, but not by Mas receptor blocker. Additionally, the levels of LDH and inflammatory cytokines, such as TNF-α, MCP-1, IL-1β, and IL-6, in plasma were lower in Ang-(1-9) co-treated MCT group than in vehicle-treated MCT group. Changes in expressions of apoptosis-related proteins such as Bax, Bcl-2, Caspase-3 and -9 in the lung tissue of MCT rats were attenuated by the treatment with Ang-(1-9). These results indicate that Ang-(1-9) improves MCT-induced pulmonary hypertension by decreasing apoptosis and inflammatory reaction via AT₂R.

Sulfatase 1 mediates the inhibitory effect of angiotensin II type 2 receptor inhibitor on angiotensin II-induced hypertensive mediator expression and proliferation in vascular smooth muscle cells from spontaneously hypertensive rats / 영남의대학술지

BACKGROUND: Extracellular sulfatases (Sulfs), sulfatase 1 (Sulf1) and sulfatase 2 (Sulf2), play a pivotal role in cell signaling by remodeling the 6-O-sulfation of heparan sulfate proteoglycans on the cell surface. The present study examined the effects of Sulfs on angiotensin II (Ang II)-induced hypertensive mediator expression and vascular smooth muscle cells (VSMCs) proliferation in spontaneously hypertensive rats (SHR). METHODS: Ang II receptors, 12-lipoxygenase (12-LO), and endothelin-1 (ET-1) messenger RNA (mRNA) expressions in SHR VSMCs were analyzed by real-time polymerase chain reaction and Western blotting. VSMCs proliferation was determined by [³ H]-thymidine incorporation. RESULTS: Basal Sulfs mRNAs expression and enzyme activity were elevated in SHR VSMCs. However, Sulfs had no effect on the basal or Ang II-induced 12-LO and ET-1 mRNA expression in SHR VSMCs. The inhibition of Ang II-induced 12-LO and ET-1 expression by blockade of the Ang II type 2 receptor (AT₂ R) pathway was not observed in Sulf1 siRNA-transfected SHR VSMCs. However, Sulf2 did not affect the action of AT₂ R inhibitor on Ang II-induced 12-LO and ET-1 expression in SHR VSMCs. The down-regulation of Sulf1 induced a reduction of AT₂ R mRNA expression in SHR VSMCs. In addition, the inhibition of Ang II-induced VSMCs proliferation by blockade of the AT₂ R pathway was mediated by Sulf1 in SHR VSMCs. CONCLUSION: These findings suggest that extracellular sulfatase Sulf1 plays a modulatory role in the AT₂ R pathway that leads to an Ang II-induced hypertensive effects in SHR VSMCs.

Sulfatase 1 mediates the inhibitory effect of angiotensin II type 2 receptor inhibitor on angiotensin II-induced hypertensive mediator expression and proliferation in vascular smooth muscle cells from spontaneously hypertensive rats / 영남의대학술지

BACKGROUND: Extracellular sulfatases (Sulfs), sulfatase 1 (Sulf1) and sulfatase 2 (Sulf2), play a pivotal role in cell signaling by remodeling the 6-O-sulfation of heparan sulfate proteoglycans on the cell surface. The present study examined the effects of Sulfs on angiotensin II (Ang II)-induced hypertensive mediator expression and vascular smooth muscle cells (VSMCs) proliferation in spontaneously hypertensive rats (SHR).METHODS: Ang II receptors, 12-lipoxygenase (12-LO), and endothelin-1 (ET-1) messenger RNA (mRNA) expressions in SHR VSMCs were analyzed by real-time polymerase chain reaction and Western blotting. VSMCs proliferation was determined by [³ H]-thymidine incorporation.RESULTS: Basal Sulfs mRNAs expression and enzyme activity were elevated in SHR VSMCs. However, Sulfs had no effect on the basal or Ang II-induced 12-LO and ET-1 mRNA expression in SHR VSMCs. The inhibition of Ang II-induced 12-LO and ET-1 expression by blockade of the Ang II type 2 receptor (AT₂ R) pathway was not observed in Sulf1 siRNA-transfected SHR VSMCs. However, Sulf2 did not affect the action of AT₂ R inhibitor on Ang II-induced 12-LO and ET-1 expression in SHR VSMCs. The down-regulation of Sulf1 induced a reduction of AT₂ R mRNA expression in SHR VSMCs. In addition, the inhibition of Ang II-induced VSMCs proliferation by blockade of the AT₂ R pathway was mediated by Sulf1 in SHR VSMCs.CONCLUSION: These findings suggest that extracellular sulfatase Sulf1 plays a modulatory role in the AT₂ R pathway that leads to an Ang II-induced hypertensive effects in SHR VSMCs.

Influence of PD 123319 (AT2-Receptor Antagonist) on Catecholamine Secretion in the Perfused Rat Adrenal Medulla

BACKGROUND: The aim of this study was to examine whether PD 123319 (an angiotensin II type 2 [AT2] receptor antagonist) can influence the release of catecholamines (CA) from the perfused model of the rat adrenal medulla. METHODS: The adrenal gland was isolated by the modification of Wakade method, and perfused with normal Krebs-bicarbonate solution. The content of CA was measured using the fluorospectrophotometer. RESULTS: During perfusion of PD 123319 (range, 5 to 50 nM) into an adrenal vein for 90 minutes the CA secretory responses evoked by acetylcholine (ACh), high K+, 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP), and McN-A-343 was dose- and time-dependently inhibited. Furthermore, loading with PD 123319 for 90 minutes also markedly inhibited the CA secretory responses evoked by 4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoro-methyl-phenyl)-pyridine-5-carboxylate (Bay-K-8644), cyclopiazonic acid, veratridine, and angiotensin II (Ang II). PD 123319 did not affect basal CA output. Simultaneous perfusion of PD 123319 and CGP 42112 perfused into an adrenal vein for 90 minutes rather more potently inhibited the CA seretory responses evoked by Ach, high K+, DMPP, Bay-K-8644, veratridine, and Ang II compared to the inhibitory effect by PD123319-treated alone. CONCLUSIONS: Taken together, these results show that PD 123319 inhibits the CA secretion evoked by both cholinergic and Ang II receptor stimulation from the perfused rat adrenal medulla. This inhibitory effect of PD 123319 seems to be exerted by blocking the influx of both Na+ and Ca2+ through their voltage-dependent channels into the rat adrenomedullary chromaffin cells as well as by reducing the Ca2+ release from its cytoplasmic calcium store, which may be relevant to AT2 receptor blockade. Based on these present data, it is thought that PD 123319 has different activity from previously known AT2 antagonist activity in the perfused adrenal medulla, and that AT2 receptors may be involved in the rat adrenomedullary CA secretion.

Downregulation of Angiotensin II-Induced 12-Lipoxygenase Expression and Cell Proliferation in Vascular Smooth Muscle Cells from Spontaneously Hypertensive Rats by CCL5

Angiotensin II (Ang II) plays an important role in vascular hypertension. The role of the chemokine CCL5 on Ang II-induced activities in vascular smooth muscle cells (VSMCs) has not been studied. In this study, we elucidated the effect of CCL5 on Ang II-induced 12-lipoxygenase (LO) expression and cell proliferation in spontaneously hypertensive rats (SHR) VSMCs. CCL5 decreased Ang II-induced 12-LO mRNA expression and protein production, and it increased Ang II type 2 (AT2) receptor expression in SHR VSMCs. The inhibitory effect of CCL5 on Ang II-induced 12-LO mRNA expression was mediated through the AT2 receptor. Although treatment of CCL5 alone induced SHR VSMCs proliferation, CCL5 inhibited Ang II-induced VSMCs proliferation and PD123,319, an AT2 receptor antagonist, blocked the inhibitory effect of CCL5 on Ang II-induced VSMCs proliferation. Phosphorylation of p38 was detected in VSMCs treated with Ang II or CCL5 alone. But, decrease of p38 phosphorylation was detected in VSMCs treated with Ang II and CCL5 simultaneously (Ang II/CCL5) and PD123,319 increased p38 phosphorylation in VSMCs treated with Ang II/CCL5. Therefore, these results suggest that the inhibitory effect of CCL5 on Ang II-induced VSMCs proliferation is mediated by the AT2 receptor via p38 inactivation, and CCL5 may play a beneficial role in Ang II-induced vascular hypertension.