Expression Of Angiotensin Receptors Research Articles

Cell type-specific expression of angiotensin receptors in the human lung with implications for health, aging, and chronic disease.

The renin-angiotensin system is a highly characterized integrative pathway in mammalian homeostasis whose clinical spectrum has been expanded to lung disorders such as chronic obstructive pulmonary disease (COPD)-emphysema, idiopathic pulmonary fibrosis (IPF), and COVID pathogenesis. Despite this widespread interest, specific localization of this receptor family in the mammalian lung is limited, partially due to the imprecision of available antibody reagents. In this study, we establish the expression pattern of the two predominant angiotensin receptors in the human lung, AGTR1 and AGTR2, using complementary and comprehensive bulk and single-cell RNA-sequence datasets that are publicly available. We show these two receptors have distinct localization patterns and developmental trajectories in the human lung, pericytes for AGTR1 and a subtype of alveolar epithelial type 2 cells for AGTR2. In the context of disease, we further pinpoint AGTR2 localization to the COPD-associated subpopulation of alveolar epithelial type 2 (AT2B) and AGTR1 localization to fibroblasts, where their expression is upregulated in individuals with COPD, but not in individuals with IPF. Finally, we examine the genetic variation of the angiotensin receptors, finding AGTR2 associated with lung phenotype (i.e., cystic fibrosis) via rs1403543. Together, our findings provide a critical foundation for delineating this pathway's role in lung homeostasis and constructing rational approaches for targeting specific lung disorders.

Angiotensin-converting enzyme inhibitors for ovarian cancer? - a new adjuvant option or a silent trap.

Ovarian cancer is a huge therapeutic and financial problem for which approved treatments have already achieved their limit of efficiency. A cost-effective strategy to extend therapeutic options in this malignancy is drug repurposing aimed at overcoming chemoresistance. Here, angiotensin-converting enzyme inhibitors (ACE-I) are worth considering. We searched literature for publications supporting the idea of adjuvant application of ACE-Is in ovarian malignancy. Then, we searched The Cancer Genome Atlas databases for relevant alternations of gene expression patterns. We also performed in silico structure-activity relationship evaluation for predicting ACE-Is' cytotoxicity against ovarian cancer cell lines. Finally, we reviewed the potential obstacles in ACE-Is repurposing process. The alternation of angiotensin receptor expression in ovarian cancer translates into poorer patient survival. This confirms the participation of the renin-angiotensin system in ovarian carcinogenesis. In observational studies, ACE-Is were shown synergize with both, platinum-based chemotherapy as well as with antiangiogenic therapy. Consistently, our in silico simulation showed that ACE-Is are probably cytotoxic against ovarian cancer cells. However, the publications on their chemopreventive properties were inconclusive. In addition, some reports correlated ACE-Is use with increased general cancer incidence. We hypothesized that this effect could be associated with mutagenic nitrosamine formation in ACE-Is' pharmaceutical formulations, as was the case with angiotensin receptor blockers (ARBs) and other well-established pharmaceuticals. Available data warrant further research into repositioning ACE-Is to ovarian cancer as chemosensitizers. Prior to this, however, a special research program is needed to detect possible genotoxic contaminants of ACE-Is.

MWF RAT AS A NOVEL ANIMAL MODEL OF CARDIORENAL SYNDROME TYPE IV

Objective: Cardiorenal syndrome type 4 (CRS type 4) is characterized by primary chronic kidney disease (CKD) leading to cardiac dysfunction and an increase in cardiovascular events. There is an unmet need for suitable animal models of CRS to further define the pathogenesis and progression of CRS to test new therapeutic strategies. We aim to determine if CKD in aged Munich Wistar Frömter (MWF) rat may translate to cardiovascular alterations of CRS. Design and method: Profibrotic markers and angiotensin receptor (ATR) expression was measured by RT-q-PCR in kidney, aorta and heart from 22 and 45-week-old (aged) male MWF rats (n = 7-10/group). Results: Aged MWF showed higher renal expression of tubular damage markers (Kim-1 and Ngal) and profibrotic factors (Col1A1, Col3A1, TGF-beta) together with lower levels of AT2R. Thoracic aorta also exhibited increased expression of profibrotic CTGF-1 and Col1-A1, as well as a lower AT2R expression. Both age groups were hypertensive with similar systolic and diastolic blood pressure levels. However, aged MWF had an increased PWV and heart weight, together with increased intrinsic arterial stiffness and an outward hypertrophic remodeling in mesenteric arteries. In 45-week-old MWF, levels of cardiac CTGF-1, AT1R and AT2R were higher, whereas TGF-beta expression was lower. No differences were observed for Col1A1 or Col3A1. Conclusions: The presence of renal and vascular fibrosis, hypertension, arterial stiffness and cardiac hypertrophy, together with inflammation, vascular remodeling and early profibrotic cardiac environment, potentially counterregulated by AT2R make aged-MWF rat an useful model for CRS study.

Aging modifies receptor expression but not muscular contractile response to angiotensin II in rat jejunum

The involvement of renin-angiotensin system in the modulation of gut motility and age-related changes in mRNA expression of angiotensin (Ang II) receptors (ATR) are well accepted. We aimed to characterize, in vitro, the contractile responses induced by Ang II, in jejunum from young (3–6 weeks old) and old rats (≥ 1 year old), to evaluate possible functional differences associated to changes in receptor expression. Mechanical responses to Ang II were examined in vitro as changes in isometric tension. ATR expression was assessed by qRT-PCR. Ang II induced a contractile effect, antagonized by losartan, AT1R antagonist, and increased by PD123319, AT2R antagonist, as well by neural blocker ω-conotoxin and by nitric oxide (NO) synthase inhibitor. No difference in the response was observed between young and old groups. AT1 receptor-mediated contractile response was decreased by U-73122, phospholipase C (PLC) inhibitor; or 2-aminoethoxy-diphenylborate (2-APB), inositol triphosphate (IP3) receptor inhibitor; or nifedipine, l-type calcium channel blocker. Age-related changes in the expression of both AT1 receptor subtypes, AT1a and AT1b, and of AT2 receptors were detected. In conclusion, Ang II modulates the spontaneous contractility of rat jejunum via postjunctional AT1 receptors, involving Ca2+ mobilization from intracellular stores, via PLC/IP3 pathway, and Ca2+ influx from extracellular space, via l-type channels. Prejunctional AT2 receptors would counteract AT1 receptor effects, via NO synthesis. The observed age-related differences in the expression of all AT receptor subtypes are not reflected in the muscular contractile response to Ang II.

Moderate Physical Exercise Activates ATR2 Receptors, Improving Inflammation and Oxidative Stress in the Duodenum of 2K1C Hypertensive Rats.

Background: In addition to the cardiovascular and renal systems, the gastrointestinal tract also contains angiotensin ATR1a, ATR1b, and ATR2. We previously observed that the 2Kidney-1Clip hypertension model elicits physical exercise and gastrointestinal dysmotility, which is prevented by renin-angiotensin system blockers. Here, we investigate the effect of physical exercise on inflammation, stress biomarkers, and angiotensin II receptors in the duodenum of 2K1C rats.Methods: Arterial hypertension was induced by the 2K1C surgical model. The rats were allocated in Sham, 2K1C, or 2K1C+Exercise groups. One week after surgery, they were submitted to a physical exercise protocol (running 5x/week, 60min/day). Next, we assessed their intestinal contractility, cytokine levels (TNF-α, IL-1β, and IL-6), oxidative stress levels (MPO, GSH, MDA, and SOD), and the gene expression of angiotensin receptors (ATR1A, ATR1B, and ATR2).Results: In comparison with the Sham group, the 2K1C arterial hypertension decreased (p<0.05) the intestinal contractility. In comparison with 2K1C, the 2K1C+Exercise group exhibited lower (p<0.05) MPO activity (22.04±5.90 vs. 78.95±18.09 UMPO/mg tissue) and higher (p<0.05) GSH concentrations in intestinal tissues (67.63±7.85 vs. 31.85±5.90mg NPSH/mg tissue). The 2K1C+Exercise group showed lower (p<0.05) cytokine levels in the intestine than 2K1C rats. In comparison with the Sham group, the 2K1C+Exercise rats showed higher (p<0.05) gene expression of ATR2 in the duodenum.Conclusion: 2K-1C hypertension elicits an oxidative stress and inflammation process in the duodenum. Physical exercise modulates the expression twice as much of ATR2 receptors, suggesting possible anti-inflammatory and antioxidant effects induced by exercise.

Dopamine regulates adult neurogenesis in the ventricular-subventricular zone via dopamine D3 angiotensin type 2 receptor interactions.

Adult neurogenesis is a dynamic and highly regulated process, and different studies suggest that dopamine modulates ventricular-subventricular zone (V-SVZ) neurogenesis. However, the specific role of dopamine and the mechanisms/factors underlying its effects on physiological and pathological conditions such as Parkinson's disease (PD) are not fully understood. Recent studies have described counter-regulatory interactions between renin-angiotensin system (RAS) and dopamine in peripheral tissues and in the nigrostriatal system. We have previously demonstrated that angiotensin receptors regulate proliferation and generation of neuroblasts in the rodent V-SVZ. However, possible interactions between dopamine receptors and RAS in the V-SVZ and their role in alterations of neurogenesis in animal models of PD have not been investigated. In V-SVZ cultures, activation of dopamine receptors induced changes in the expression of angiotensin receptors. Moreover, dopamine, via D2-like receptors and particularly D3 receptors, increased generation of neurospheres derived from the V-SVZ and this effect was mediated by angiotensin type-2 (AT2) receptors. In rats, we observed a marked reduction in proliferation and generation of neuroblasts in the V-SVZ of dopamine-depleted animals, and inhibition of AT1 receptors or activation of AT2 receptors restored proliferation and generation of neuroblasts to control levels. Moreover, intrastriatal mesencephalic grafts partially restored proliferation and generation of neuroblasts observed in the V-SVZ of dopamine-depleted rats. Our data revealed that dopamine and angiotensin receptor interactions play a major role in the regulation of V-SVZ and suggest potential beneficial effects of RAS modulators on the regulation of adult V-SVZ neurogenesis.

Programming by Methyl Donor Deficiency during Pregnancy and Lactation Produces Cardiomyopathy in Adult Rats Subjected to High Fat Diet.

Vitamin B12 and folate (methyl donors) deficiency is frequent during pregnancy. Experimental rat models with methyl donor deficit during pregnancy and lactation (Initial methyl donor deficit (iMDD)) produce impaired myocardium fatty acid oxidation and mitochondrial energy metabolism at weaning. The consequences of iMDD on heart of rat pups under normal diet after weaning and high fat diet (HF) between day (D) 50 and D185 are investigated. iMDD/HF induces increased histological fibrosis and increased B-type natriuretic peptide blood level. Inflammation is evidenced by increased protein expression of NFkB, Caspase1, and IL1β and fibrosis by increased expression of αSMA, col1a1, and col1a2 in females, but not in males. Fibrosis is related to increased angiotensin at D50 and D185 and increased protein expression of TGFB1 and AT1 angiotensin receptors at D185. The limited fibrosis in males is consistent with increased expression of AT2, the antagonist receptor of AT1. The increased expression of GLUT4 and decreased expression of PGC1α and PPARα reflect a shift from fatty acid oxidation to glycolysis. Developmental programming by iMDD produces cardiomyopathy in female offspring exposed to HF. The cardiomyopathy is linked to inflammation and fibrosis through angiotensin-AT2 and TGFB1 pathways and alteration of energy metabolism.

Effects of inverted photoperiods on the blood pressure and carotid artery of spontaneously hypertensive rats and Wistar-Kyoto rats.

The objective of this study was to investigate the effects of inverted photoperiods on the blood pressure and carotid arteries in spontaneously hypertensive rats (SHRs) and Wistar-Kyoto (WKY) rats (homologous control group). This study used two inverted photoperiods [inverted light:dark (ILD)16 : 8 and ILD12 : 12] to create the model. A total of 27 male SHR and 27 male WKY rats were randomly divided into six groups (nine rats per group): SHR (LD12 : 12), SHR (ILD16 : 8), SHR (ILD12 : 12), WKY (LD12 : 12), WKY (ILD16 : 8) and WKY (ILD12 : 12). We recorded the trajectory of the activity rhythm of the rats and performed carotid vascular ultrasound examination, MRI (arterial spin labelling) analysis and carotid biopsy. The results showed that inverted photoperiods increased the blood pressure, carotid intima-media thickness, resistance index and blood flow velocity. In addition, inverted photoperiods led to the development of carotid arterial thrombosis, significantly reduced cerebral blood flow and increased the number of collagen fibres. Moreover, it increased the expression of angiotensin receptor and low-density lipoprotein receptor in the carotid arteries, leading to decreased expression of 3-hydroxy-3-methylglutaryl-Coenzyme A reductase and nitric oxide synthase. Inverted photoperiods induced the formation of atherosclerotic plaque. Multiple results of SHR were worse than those of WKY rats. Taken together, inverted photoperiods can produce a series of adverse consequences on blood pressure and carotid arteries. Hypertension can aggravate the adverse effects of inverted photoperiods.

Estrogen Deficiency and Colonic Function: Surgical Menopause and Sex Differences in Angiotensin and Dopamine Receptor Interaction.

The physiopathological mechanisms that regulate menopausal and sex differences in colonic transit, inflammatory processes, and efficacy of treatments have not been clarified. The dopaminergic system and renin-angiotensin system coexist in the gut and regulate different processes such as motility, absorption/secretion, and inflammation. We investigated the changes in expression of major angiotensin and dopamine receptors in the colon of male, female, and ovariectomized female mice. Possible interaction between both systems was investigated using male and female mice deficient (ko) for major angiotensin and dopamine receptors. In wild-type mice, colonic tissue from females showed lower angiotensin type 1/angiotensin type 2 ratio (an index of pro-inflammatory/anti-inflammatory renin-angiotensin system balance), lower dopamine D1 and D2 receptor expression, and lower levels of pro-inflammatory and pro-oxidative markers relative to males. Interestingly, ovariectomy increased the expression of pro-inflammatory angiotensin type 1 receptor expression and decreased anti-inflammatory angiotensin type 2 receptor expression, increased D1 and D2 receptor expression, and increased the levels of pro-inflammatory and pro-oxidative markers. Ovariectomy-induced changes were blocked by estrogen replacement. The present results suggest a mutual regulation between colonic angiotensin and dopamine receptors and sex differences in this mutual regulation. Estrogen regulates changes in both angiotensin and dopamine receptor expression, which may be involved in sex- and surgical menopause-related effects on gut motility, permeability, and vulnerability to inflammatory processes.

The protective role of melatonin against the effects of different doses of caffeine on the fetus

Skeletal system and some organs development changes in rat fetuses with 30 and 60 mg/kg caffeine and melatonin's (10 mg/kg) protective role against rat fetuses were investigated. Groups (n = 4) were formed as Control, LDC, HDC, LDC+melatonin, HDC+melatonin and melatonin. Fetuses were taken by cesarean section and stained using dual skeletal staining method and FESEM. TRAP and AP immune-reactivity concentrations were calculated. Oxidative stress and inflammatory markers were also measured by liver, bone and placenta samples. TNF-α, IL-1ß, IL-6, VEGF-A, SOST and Fetuin-A levels were measured in tissue by using ELISA. TBARS, SOD, GSH, GSSG, TOS, TAS, measured by spectrophotometric assay method. The mRNA levels of Agtr2 gene expressed in placental tissues of control rats and in placental tissues of rats exposed to HDC, LDC, MEL, HDC+MEL, LDC+MEL were analyzed by Real-time PCR. The gene expressions of Agtr2 were significantly upregulated in the placentas exposed to HDC, MEL, HDC+MEL and LDC+MEL (P&lt;0,001). No significant difference in samples of the LDC group (P&gt;0,05). According to these data, caffeine used during pregnancy delayed ossification; melatonin, a powerful antioxidant, was found to eliminate this effect. Besides, changes in angiotensin receptor expression observed in response to a caffeine and melatonin exposure result from high dose and join effect.

Histone Deacetylase Inhibition Attenuates Aortic Remodeling in Rats under Pressure Overload.

The use of histone deacetylase (HDAC) inhibitor is a novel therapeutic strategy for cardiovascular disease. Studies have shown that many HDAC inhibitors have the ability to reduce the aortic remodeling in various animal models. We hypothesized that the HDAC inhibitor, MGCD0103 (MGCD), attenuates aortic remodeling in rats under pressure overload-induced by transverse aortic constriction (TAC). The aortic ring tension analysis was conducted using the thoracic aorta. Sections of the aorta were visualized after hematoxylin and eosin, trichrome, and Verhoeff-van Gieson staining, and immunohistochemistry. The expression of genes related to aortic remodeling (αSMA, Mmp2, and Mmp9) and angiotensin receptors (Agtr1 and Agtr2) was determined by quantitative real-time polymerase chain reaction. There was a significant decrease in relaxation of the aorta when treated with MGCD. Fibrosis of the aortic wall and expression of angiotensin receptors increased in TAC rats, which was attenuated by MGCD. These results indicate that MGCD, an HDAC inhibitor, attenuates aortic remodeling in rats with TAC-induced pressure overload rats and may serve as a potential therapeutic target of antiaortic remodeling in pressure overload-induced hypertension-related diseases.

Sinapic Acid Attenuates Cardiovascular Disorders in Rats by Modulating Reactive Oxygen Species and Angiotensin Receptor Expression.

The main avoidable risk factor for cardiovascular conditions is high blood pressure (hypertension). At global level, hypertension is believed to be responsible for a 54% stroke-related mortality rate and a 47% mortality rate associated with coronary heart disease. It is postulated that sinapic acid (SA) could help in hypertension management because it displays robust antioxidant, antihyperglycemic, and peroxynitrite scavenging effects. To explore this hypothesis, this work examined the effect of SA on oxidative stress and cardiovascular disease in rats with hypertension by comparison against captopril. For this purpose, 50 male rats were used and equally allocated to five groups, namely, normal control, positive control (L-NAME), L-NAME with concomitant captopril administration, L-NAME with concomitant SA administration, and L-NAME with concomitant administration of both SA and captopril. Results showed that, by contrast to control, L-NAME exhibited marked elevation in serum CK-MB, total cholesterol, triglycerides, VLDL-C, LDL-C, Ang II, AT2R, ET-1, and angiopoietin-2; on the other hand, L-NAME exhibited marked reduction in serum HDL-C, superoxide dismutase (SOD) activity, nitric oxide synthase 3 (NOS3), and glutathione (GSH). Furthermore, joint administration of SA and captopril ameliorated hypertension, enhanced cardiovascular function, hindered hyperlipidemia, and decreased oxidative stress and myocardial hypertrophy displayed by rats with hypertension. Based on such findings, better chemopreventive or therapeutic approaches can be devised to manage hypertension and cardiovascular conditions.

Angiotensin‐(1‐7) Improves Integrated Cardiometabolic Function in Aged Mice

BackgroundAging is associated with impaired cardiometabolic function including insulin resistance, elevated blood pressure, and cardiac hypertrophy. Angiotensin (Ang)‐(1‐7) is a beneficial hormone of the renin‐angiotensin system that improves control of blood pressure and glucose homeostasis in models of cardiovascular and metabolic diseases in young mice. To our knowledge, no studies have evaluated the importance of Ang‐(1‐7) to integrated cardiometabolic function in aging. We hypothesized that Ang‐(1‐7) would improve insulin sensitivity as well as decrease blood pressure and cardiac hypertrophy in healthy aged mice.MethodsSixteen month‐old male C57BL/6J mice received 6‐week Ang‐(1‐7) [400 ng/kg/min, n=9] or saline infusion (n=9) via subcutaneous osmotic mini‐pumps. All mice were fed standard chow diet (18% kcal from fat). During the last week of treatment, intraperitoneal insulin and glucose tolerance tests were performed and blood pressure was measured via a carotid artery catheter. Heart weight was measured at the end of experiments. Gene expression of tyrosine hydroxylase (index of sympathetic activity), inflammatory markers (IL10, IL1β, IL6, TNFα) and Ang II AT1 and Ang‐(1‐7) Mas receptors were measured in myocardial tissue by quantitative real‐time PCR and quantified with 2‐ΔΔCT methods.ResultsWe found that Ang‐(1‐7) decreased systolic [Ang‐(1‐7): 105±2 mmHg, saline: 116±4 mmHg, P=0.031], diastolic [Ang‐(1‐7): 77±2 mmHg, saline: 83±2 mmHg, P=0.041], and mean [Ang‐(1‐7): 86±2 mmHg, saline: 94±3 mmHg, P = 0.023] blood pressure. Furthermore, Ang‐(1‐7) reduced heart weight [Ang‐(1‐7): 0.18±0.01 g; saline: 0.21±0.01 g, P=0.042]. The improvement in cardiac hypertrophy with Ang‐(1‐7) was associated with decreased tyrosine hydroxylase gene expression in the heart [Ang‐(1‐7): 0.4±0.1, saline: 0.9±0.1, p=0.014], with no effect on gene expression of inflammatory markers or angiotensin receptors (p&gt;0.3). Ang‐(1‐7) did not alter body mass [Ang‐(1‐7): 46.5±2.0 g, saline: 45.9±1.5 g, p=0.792] or body composition (p&gt;0.2). Ang‐(1‐7) also improved insulin sensitivity [Ang‐(1‐7): −2896±593 AUC, saline:‐1171 ± 624 AUC, p=0.033] but did not affect fasting glucose levels [Ang‐(1‐7): 180±5 mg/dL, saline: 169±8 mg/dL, p=0.225] or glucose tolerance (p=0.202).ConclusionsChronic Ang‐(1‐7) treatment decreases blood pressure, cardiac hypertrophy, and markers of cardiac sympathetic activity as well as increases insulin sensitivity in aged mice. These beneficial cardiometabolic effects of Ang‐(1‐7) occurred in the absence of significant changes in body weight or composition. Overall, these data suggest that Ang‐(1‐7) may provide a novel pharmacological target to improve age‐related cardiovascular and metabolic risk.Support or Funding InformationNIH Pathway to Independence Award: R00 HL122507 to A.C. ArnoldAHA Postdoctoral Fellowship: 18POST33960087 to A.J. Miller

Examination of Cardioprotective Effects of Fabomotizole Hydrochloride in Translational Rat Model of Chronic Heart Failure.

A translational rat model of chronic heart failure was employed to examine the cardioprotective effect of fabomotizole hydrochloride. Fabomotizole therapy for 28 days (15 mg/kg/day intraperitoneally) restored inotropic function of the left ventricle and increased ejection fraction from 54±3 to 65±3% (p=0.001). The inotropic function returned to normal against the background of significantly reduced myocardial expression of angiotensin (p=0.01) and glucocorticoid (p=0.03) receptors and significant increased expression of sigma-1 receptors (p=0.04). Inhibition of abnormal expression of angiotensin and glucocorticoid receptors responsible for activation of the pathological cascades underlying the postinfarction remodeling of the left ventricle as well as activation of the expression of cytoprotective sigma-1 receptors are viewed as the key features of the cardioprotective action of fabomotizole hydrochloride.

Angiotensin receptor expression revealed by reporter mice and beneficial effects of AT2R agonist in retinal cells

The renin-angiotensin system (RAS) plays a vital role in cardiovascular physiology and body homeostasis. In addition to circulating RAS, a local RAS exists in the retina. Dysfunction of local RAS, resulting in increased levels of Angiotensin II (Ang II) and activation of AT1R-mediated signaling pathways, contributes to tissue pathophysiology and end-organ damage. Activation of AT2R on other hand is known to counteract the effects of AT1R activation and produce anti-inflammatory and anti-oxidative effects. We examined the expression of angiotensin receptors in the retina by using transgenic dual reporter mice and by real-time RT-PCR. We further evaluated the effects of C21, a selective agonist of AT2R, in reducing Ang II, lipopolysaccharide (LPS) and hydrogen peroxide induced oxidative stress and inflammatory responses in cultured human ARPE-19 cells. We showed that both AT1Ra and AT2R positive cells are detected in different cell types of the eye, including the RPE/choroid complex, ciliary body/iris, and neural retina. AT1Ra is more abundantly expressed than AT2R in mouse retina, consistent with previous reports. In the neural retina, AT1Ra are also detected in photoreceptors whereas AT2R are mostly expressed in the inner retinal neurons and RGCs. In cultured human RPE cells, activation of AT2R with C21 significantly blocked Ang II, LPS and hydrogen peroxide -induced NF-κB activation and inflammatory cytokine expression; Ang II and hydrogen peroxide-induced reactive oxygen species (ROS) production and MG132-induced apoptosis, comparable to the effects of Angiotensin-(1–7) (Ang-(1–7)), another protective component of the RAS, although C21 is more potent in reducing some of the effects induced by Ang II, whereas Ang-(1–7) is more effective in reducing some of the LPS and hydrogen peroxide-induced effects. These results suggest that activation of AT2R may represent a new therapeutic approach for retinal diseases.

Blockade of myeloid differentiation 2 attenuates diabetic nephropathy by reducing activation of the renin-angiotensin system in mouse kidneys.

Both innate immunity and the renin-angiotensin system (RAS) play important roles in the pathogenesis of diabetic nephropathy (DN). Myeloid differentiation factor 2 (MD2) is a co-receptor of toll-like receptor 4 (TLR4) in innate immunity. While TLR4 is involved in the development of DN, the role of MD2 in DN has not been characterized. It also remains unclear whether the MD2/TLR4 signalling pathway is associated with RAS activation in diabetes. MD2 was blocked using siRNA or the low MW inhibitor, L6H9, in renal proximal tubular cells (NRK-52E cells) exposed to high concentrations of glucose (HG). In vivo, C57BL/6 and MD2-/- mice were injected with streptozotocin to induce Type 1 diabetes and nephropathy. Inhibition of MD2 by genetic knockdown or the inhibitor L6H9 suppressed HG-induced expression of ACE and angiotensin receptors and production of angiotensin II in NRK-52E cells, along with decreased fibrosis markers (TGF-β and collagen IV). Inhibition of the MD2/TLR4-MAPKs pathway did not affect HG-induced renin overproduction. In vivo, using the streptozotocin-induced diabetic mice, MD2 was overexpressed in diabetic kidney. MD2 gene knockout or L6H9 attenuated renal fibrosis and dysfunction by suppressing local RAS activation and inflammation. Hyperglycaemia activated the MD2/TLR4-MAPKs signalling cascade to induce renal RAS activation, leading to renal fibrosis and dysfunction. Pharmacological inhibition of MD2 may be considered as a therapeutic approach to mitigate DN and the low MW inhibitor L6H9 could be a candidate for such therapy.

Comparative Expression of Renin-Angiotensin Pathway Proteins in Visceral Versus Subcutaneous Fat.

Body fat distribution contributes to obesity-related metabolic and cardiovascular disorders. Visceral fat is more detrimental than subcutaneous fat. However, the mechanisms underlying visceral fat-mediated cardiometabolic dysregulation are not completely understood. Localized increases in expression of the renin angiotensin system (RAS) in adipose tissue (AT) may be implicated. We therefore investigated mRNA and protein expression of RAS components in visceral versus subcutaneous AT using paired samples from individuals undergoing surgery (N = 20, body mass index: 45.6 ± 6.2 kg/m2, and age: 44.6 ± 9.1 years). We also examined RAS-related proteins in AT obtained from individuals on renin angiotensin aldosterone system (RAAS) targeted drugs (N = 10, body mass index: 47.2 ± 9.3 kg/m2, and age: 53.3 ± 10.1 years). Comparison of protein expression between subcutaneous and visceral AT samples showed an increase in renin (p = 0.004) and no change in angiotensinogen (p = 0.987) expression in visceral AT. Among proteins involved in angiotensin peptide generation, angiotensin converting enzyme (p = 0.02) was increased in subcutaneous AT while chymase (p = 0.001) and angiotensin converting enzyme-2 (p = 0.001) were elevated in visceral fat. Furthermore, visceral fat expression of angiotensin II type-2 receptor (p = 0.007) and angiotensin II type-1 receptor (p = 0.031) was higher, and MAS receptor (p < 0.001) was lower. Phosphorylated-p53 (p = 0.147), AT fibrosis (p = 0.138) and average adipocyte size (p = 0.846) were similar in the two depots. Nonetheless, visceral AT showed increased mRNA expression of inflammatory (TNFα, p < 0.001; IL-6, p = 0.001) and oxidative stress markers (NOX2, p = 0.038; NOX4, p < 0.001). Of note, mRNA and protein expression of RAS components did not differ between subjects taking or not taking RAAS related drugs. In summary, several RAS related proteins are differentially expressed in subcutaneous versus visceral AT. This differential expression may not alter AngII but likely increases Ang1-7 generation in visceral fat. These potential differences in active angiotensin peptides and receptor expression in the two depots suggest that localized RAS may not be involved in differences in visceral vs subcutaneous AT function in obese individuals. Our findings do not support a role for localized RAS differences in visceral fat-mediated development of cardiovascular and metabolic pathology.

Expression of AT1, AT2 and MAS receptors in renal biopsy tissue from diabetic nephropathy patients and its relationship with pathological injury

Objective To observe the expression of AT1, AT2 and MAS receptors in renal biopsy tissue from diabetic nephropathy (DN) patients, and to discuss its relationship with renal pathological injury. Methods A total of 124 patients diagnosed as DN by renal biopsy in our hospital from January 2004 to July 2017 were enrolled in our research (15 cases of class I+ IIa, 26 cases of class IIb, 76 cases of class III and 7 cases of class IV). The expression of angiotensin receptors was evaluated by immunohistochemistry and analyzed by mean density. Clinical data, protein expression of AT1, AT2 and MAS receptors in renal biopsy tissue and its relationship with pathological injury were evaluated. Results Glomerular and tubular AT1 receptor expression in patients of class III was significantly stronger than class I+ IIa, IIb and IV. Vascular AT1 receptor expression gradually weakened as the pathological injury was aggravating. Glomerular AT2 receptors expression in patients of class IIb was strongest , glomerular AT2 receptors expression weakened as the pathological injury was aggravating. Tubular AT2 receptors expression in patients of class IIb was significantly stronger than class I+ IIa, III and IV . Glomerular MAS receptor expression in patients of class I+ II was strongest , it was no difference between class IIb and III, glomerular MAS receptor expression in patients of class IV was significantly weaker than class III. Tubule and vascular MAS receptor expression were similar to glomeruli. Conclusions Expression of AT1, AT2 and MAS receptors in renal biopsy tissue is associated with pathologic injury in DN patients, which provides more evidence to elucidate the role of RAS in DN. Key words: Biopsy; Angiotensins; Diabetic Nephropathies

Zingerone alleviates the delayed ventricular repolarization and AV conduction in diabetes: Effect on cardiac fibrosis and inflammation.

BackgroundThe study aims to analyse the action of zingerone in diabetes-related cardiac arrhythmias.MethodsDiabetes was induced by streptozocin while treatment groups received 20 mg/kg zingerone daily. Following extra seven weeks, electrocardiography, extraction of blood, urine and heart for biochemical analysis, histopathology and immunofluorescence were undertaken.ResultsThe suppression of QT and QTc prolongation in diabetic rats was indicative of prolonged cardiac repolarisation that was greatly reduced by zingerone treatment. In addition, the reduction in PR interval attested that zingerone improved AV delay in diabetic rats. The fibrogenic transforming growth factor β1 upregulation in diabetic hearts was suppressed by zingerone. The marked glycogen deposition and muscle degeneration seen in diabetic heart sections were also alleviated by zingerone. Furthermore, zingerone prevented the decrease in of the serum anti-inflammatory cytokine adiponectin in diabetics. The heightened levels of oxidative stress markers 8-isoprostane and uric acid in diabetic rats were suppressed. In the diabetic heart, the reduced catalase activity was improved and the excessive expression of angiotensin receptor 1 was inhibited by zingerone.ConclusionCardiac delayed repolarisation and AV conduction in rats with diabetes were halted by zingerone. It appears that inhibition of cardiac fibrosis and associated inflammation-oxidative stress signalling underpins the zingerone effect.

The Beneficial Effects of Allicin in Chronic Kidney Disease Are Comparable to Losartan.

Recent studies suggest that allicin may play a role in chronic kidney disease (CKD), reducing hypertension and oxidative stress and improving renal dysfunction. In the present study, CKD was induced by 5/6 nephrectomy and the animals were divided into four treatment groups as follows: control (C), CKD, CKD+allicin (40 mg/kg pathway oral) (CKDA), and CKD+Losartan (20 mg/kg) (CKDL). After CKD induction, the rats developed hypertension from week 3 to the end of the study. This was associated with increased creatinine and blood urea nitrogen (BUN) levels in serum, increased albuminuria, increased urinary excretion of N-acetyl-β-d-glucosaminidase (NAG), increased nephrin expression, and incrased histological alterations in the cortex. The levels of angiotensin receptors and endothelial nitric oxide synthase (eNOS) were decreased in the renal cortex from the CKD group. Otherwise, lipid and protein oxidation were higher in the CKD group than in the control group. A disturbance was observed in the expression levels of the nuclear factor erythroid 2-related factor 2/Kelch ECH associating protein 1 system (Nrf2/keap1) and the antioxidant enzymes catalase, superoxide dismutase, and heme oxygenase-1. Allicin or losartan treatments relieved renal dysfunction, hypertension, and oxidative stress. In addition, both treatments showed the same efficacy on the expression of angiotensin receptors, the nephrin, Nrf2/keap1 pathway, and eNOS. Further in silico analyses suggest that allicin and losartan could have a common mechanism involving interaction with AT1 receptors. Allicin showed antihypertensive, antioxidant, and nephroprotective effects. The beneficial effects showed by allicin are similar, or even better, than those of losartan. In fact, the effect of allicin on blood pressure and renal function is comparable to reductions seen with losartan, a prescription drug commonly used as a first-line therapy.