Immunotherapy against angiotensin II receptor ameliorated insulin resistance in a leptin receptor-dependent manner.

The angiotensin II type 1 receptor (AT1R) signaling pathway is reported to modulate glucose metabolism. Targeting AT1R, our group invented ATRQß-001 vaccine, a novel immunotherapeutic strategy to block the activation of AT1R. Here, we evaluated the therapeutic efficacy of ATRQß-001 vaccine in insulin resistance, and investigated the mechanism. Our results showed that ATRQß-001 vaccine and specific monoclonal antibody against epitope ATR-001 (McAb-ATR) decreased fasting serum insulin concentration and improved glucose and insulin tolerance in ob/ob mice. These beneficial effects were verified in high-fat diet-induced obese mice. McAb-ATR activated insulin signaling in skeletal muscle and insulin-resistant C2C12 myotubes without affecting liver or white adipose tissue of ob/ob mice. Mechanistically, the favorable impact of McAb-ATR on insulin resistance was abolished in db/db mice and in C2C12 myotubes with leptin receptor knockdown. AT1R knockdown also eradicated the effects of McAb-ATR in C2C12 myotubes. Furthermore, McAb-ATR treatment was able to activate the leptin receptor-mediated JAK2/STAT3 signaling in skeletal muscle of ob/ob mice and C2C12 myotubes. Additionally, angiotensin II downregulated the leptin signaling in skeletal muscle of ob/ob and diet-induced obese mice. We demonstrated that ATRQß-001 vaccine and McAb-ATR improved whole-body insulin resistance and regulated glucose metabolism in skeletal muscle in a leptin receptor-dependent manner. Our data suggest that immunotherapy targeting AT1R is a novel strategy for treating insulin resistance.

Synthetic nanobodies as angiotensin receptor blockers.

There is considerable interest in developing antibodies as functional modulators of G protein-coupled receptor (GPCR) signaling for both therapeutic and research applications. However, there are few antibody ligands targeting GPCRs outside of the chemokine receptor group. GPCRs are challenging targets for conventional antibody discovery methods, as many are highly conserved across species, are biochemically unstable upon purification, and possess deeply buried ligand-binding sites. Here, we describe a selection methodology to enrich for functionally modulatory antibodies using a yeast-displayed library of synthetic camelid antibody fragments called "nanobodies." Using this platform, we discovered multiple nanobodies that act as antagonists of the angiotensin II type 1 receptor (AT1R). Following angiotensin II infusion in mice, we found that an affinity matured nanobody antagonist has comparable antihypertensive activity to the angiotensin receptor blocker (ARB) losartan. The unique pharmacology and restricted biodistribution of nanobody antagonists may provide a path for treating hypertensive disorders when small-molecule drugs targeting the AT1R are contraindicated, for example, in pregnancy.

Effect of mild moxibustion on intestinal microbiota and NLRP6 inflammasome signaling in rats with post-inflammatory irritable bowel syndrome.

BACKGROUND: About one-third of refractory irritable bowel syndrome (IBS) cases are caused by gastrointestinal (GI) infection/inflammation, known as post-infectious/post-inflammatory IBS (PI-IBS). Although it is known that intestinal microbiota and host NOD-like receptor family pyrin domain containing 6 (NLRP6) inflammsome signaling are closely related to PI-IBS and moxibustion has a therapeutic effect on PI-IBS, whether moxibustion regulates the intestinal flora and host NLRP6 events in PI-IBS remains unclear. AIM: To examine the regulatory effect of moxibustion on intestinal microbiota and host NLRP6 inflammatory signaling in PI-IBS. METHODS: Sprague-Dawley rats were divided into a normal control group, a model control group, a mild moxibustion group, and a sham mild moxibustion group. PI-IBS rats in the mild moxibustion group were treated with moxibusiton at bilateral Tianshu (ST 25) and Zusanli (ST36) for 7 consecutive days for 10 min each time. The sham group rats were given the same treatment as the mild moxibustion group except the moxa stick was not ignited. Abdominal withdrawal reflex (AWR) score was measured to assess the visceral sensitivity, and colon histopathology and ultrastructure, colonic myeloperoxidase (MPO) activity, and serum C-reactive protein (CRP) level were measured to evaluate low-grade colonic inflammation in rats. The relative abundance of selected intestinal bacteria in rat feces was detected by 16S rDNA PCR and the NLRP6 inflammsome signaling in the colon was detected by immunofluorescence, qRT-PCR, and Western blot. RESULTS: The AWR score was significantly decreased and the low-grade intestinal inflammation reflected by serum CRP and colonic MPO levels was inhibited in the mild moxibustion group compared with the sham group. Mild moxibustion remarkably increased the relative DNA abundances of Lactobacillus, Bifidobacterium, and Faecalibacterium prausnitzii but decreased that of Escherichia coli in the gut of PI-IBS rats. Additionally, mild moxibustion induced mRNA and protein expression of intestine lectin 1 but inhibited the expression of IL-1ß, IL-18, and resistance-like molecule ß by promoting the NLRP6 and reducing the mRNA and protein expression of apoptosis-associated speck-like protein containing CARD (ASC) and cysteinyl-aspartate-specific proteinase 1 (Caspase-1). The relative DNA abundances of Lactobacillus, Bifidobacteria, Faecalibacterium prausnitzii, and Escherichia coli in each group were correlated with the mRNA and protein expression of NLRP6, ASC, and Caspase-1 in the colon. CONCLUSION: These findings indicated that mild moxibustion can relieve low-grade GI inflammation and alleviate visceral hypersensitivity in PI-IBS by regulating intestinal microbes and controlling NLRP6 inflammasome signaling.

Proactive treatment of angiotensin receptor antibodies in kidney transplantation with plasma exchange and/or candesartan is safe and associated with excellent graft survival at 4 years: A single centre Australian experience.

High levels of angiotensin receptor antibodies (ATRab) are associated with acute cellular and humoral rejection, vascular occlusion, de novo human leucocyte antigen donor specific antibody (HLA DSA) and poor graft survival in kidney transplant recipients (KTR). Since 2015 we proactively managed patients "at risk" (AR) with ATRab >17 U/ml with perioperative plasma exchange (PLEX) and/or angiotensin receptor blockade (ARB). 44 patients were treated with this protocol. 265 KTR with ATRab ≤17 U/ml deemed "low risk" (LR) were transplanted under standard conditions. PLEX and ARB were not associated with increased risk of: delayed graft function requiring haemodialysis (HDx), hyperkalaemia >5.5 mmol/l requiring HDx, and the combined clinical end-point of severe hypotension, blood transfusion and re-operation for bleeding. Rejection rates were similar at 90 days: 8/44 (18%) in the AR group and 36/265 (14%) in the LR group (p = 0.350). Death censored graft survival was the same between the AR and LR groups with a 94% 48-month graft survival - hazard ratio (log-rank) 1.16 [95% CI 0.2-5.8] p = 0.844. Proactive treatment of ATRab >17 U/ml with PLEX and/or ARB is not associated with increased rates of perioperative complications and comparable rates of rejection and death censored graft survival at 4 years compared to KTR <17 U/ml ATRab.

Therapeutic benefit of mesenchymal stem cells in pregnant rats with angiotensin receptor agonistic autoantibody-induced hypertension: Implications for immunomodulation and cytoprotection.

Immunomodulation by mesenchymal stem cells (MSCs) is potentially important for maintaining peripheral tolerance. Preeclampsia may be due to maternal immune rejection of the genetically foreign fetus. This study aimed to investigate the biological function of human umbilical cord-derived mesenchymal stem cells (HU-MSCs) for the treatment of angiotensin receptor agonistic autoantibody (AT1-AA)-induced hypertension during pregnancy. HU-MSCs were isolated, cultured, and labeled in vitro. AT1-AA and HU-MSCs were administered to pregnant rats. Green fluorescent protein (GFP)-positive HU-MSCs infused in vivo were identified by immunofluorescence. Systolic blood pressure (SBP) was evaluated. The effects of HU-MSCs on fetal weight, kidney burden, and spiral artery remodeling, as well as on the expression of tumor necrosis factor α (TNF-α), interleukin 10 (IL-10), and heme oxygenase 1 (HO-1), were investigated. The SBP levels in the HU-MSC-treated pregnant hypertension rats decreased by gestational day 19. The reduction in fetal weight was largely ameliorated after HU-MSC treatment. Lesion burden in the kidney was attenuated and spiral artery remodeling was improved in HU-MSC-treated pregnant hypertension rats. However, green fluorescent protein (GFP)-labeled cells were sparingly observed in the kidney and placenta. Intravenous infusion of HU-MSCs into AT1-AA-induced rats significantly downregulated serum TNF-α levels and upregulated IL-10 levels, concomitant with increased placenta and mesometrial triangle (MT) HO-1 expression. Taken together, intravenous infusion of HU-MSCs ameliorates AT1-AA-induced pregnancy hypertension, intrauterine growth retardation, kidney impairment, and spiral artery remodeling impairment. Moreover, the potential benefits of HU-MSCs may be attributable to both an interference with the pathogenic immune response and a paracrine cytoprotective action.

Transglutaminase is a Critical Link Between Inflammation and Hypertension.

BACKGROUND: The pathogenesis of essential hypertension is multifactorial with different underlying mechanisms contributing to disease. We have recently shown that TNF superfamily member 14 LIGHT (an acronym for homologous to lymphotoxins, exhibits inducible expression, and competes with herpes simplex virus glycoprotein D for herpes virus entry mediator, a receptor expressed by T lymphocytes, also known as TNFSF14) induces hypertension when injected into mice. Research reported here was undertaken to examine the role of transglutaminase (TGase) in LIGHT-induced hypertension. METHODS AND RESULTS: Initial experiments showed that plasma and kidney TGase activity was induced by LIGHT infusion (13.91±2.92 versus 6.75±1.92 mU/mL and 19.86±3.55 versus 12.00±0.97 mU/10 µg) and was accompanied with hypertension (169±7.16 versus 117.17±11.57 mm Hg at day 14) and renal impairment (proteinuria, 61.33±23.21 versus 20.38±9.01 µg/mg; osmolality, 879.57±93.02 versus 1407.2±308.04 mmol/kg). The increase in renal TGase activity corresponded to an increase in RNA for the tissue TGase isoform, termed TG2. Pharmacologically, we showed that LIGHT-induced hypertension and renal impairment did not occur in the presence of cystamine, a well-known competitive inhibitor of TGase activity. Genetically, we showed that LIGHT-mediated induction of TGase, along with hypertension and renal impairment, was dependent on interleukin-6 and endothelial hypoxia inducible factor-1α. We also demonstrated that interleukin-6, endothelial hypoxia inducible factor-1α, and TGase are required for LIGHT-induced production of angiotensin receptor agonistic autoantibodies. CONCLUSIONS: Thus, LIGHT-induced hypertension, renal impairment, and production of angiotensin receptor agonistic autoantibodies require TGase, most likely the TG2 isoform. Our findings establish TGase as a critical link between inflammation, hypertension, and autoimmunity.

Functional Local Renin-Angiotensin System in Human and Rat Periodontal Tissue.

The initiation or progression of periodontitis might involve a local renin-angiotensin system (RAS) in periodontal tissue. The aim of this study was to further characterize the local RAS in human and rat periodontal tissues between healthy and periodontally-affected tissue. Components of the RAS were investigated using in vitro, ex vivo and in vivo experiments involving both human and Wistar rat periodontium. Although not upregulated when challenged with P. gingivalis-lipopolysaccharide, human gingival and periodontal ligament fibroblasts expressed RAS components. Likewise, healthy and inflamed human gingiva expressed RAS components, some of which were shown to be functional, yet no differences in expression were found between healthy and diseased gingiva. However, in inflamed tissue the immunoreactivity was greater for the AT1R compared to AT2R in fibroblasts. When compared to healthy tissue, ACE activity was increased in human gingiva from volunteers with gingivitis. Human-gingiva homogenates generated Ang II, Ang 1-9 and Ang 1-7 when incubated with precursors. In gingiva homogenates, Ang II formation from Ang I was nearly abolished only when captopril and chymostatin were combined. Ang 1-7 formation was significantly greater when human gingiva homogenates were incubated with chymostatin alone compared to incubation without any inhibitor, only captopril, or captopril and chymostatin. In rat gingiva, RAS components were also found; their expression was not different between healthy and experimentally induced periodontitis (EP) groups. However, renin inhibition (aliskiren) and an AT1R antagonist (losartan) significantly blocked EP-alveolar-bone loss in rats. Collectively, these data are consistent with the hypothesis that a local RAS system is not only present but is also functional in both human and rat periodontal tissue. Furthermore, blocking AT1R and renin can significantly prevent periodontal bone loss induced by EP in rats.

Relationship between autoantibody to the angiotensin II-1 receptor and cardiovascular manifestations of Graves' disease.

OBJECTIVE: To investigate the role of autoantibody against angiotensin II-1 receptor (AT1-AA) in patients with cardiovascular manifestations of Graves' disease (GD). METHODS: The epitope of the second extracellular loop of AT1 receptor (165-191) was synthesized and used as antigens to screen the autoantibody by enzyme linked immunosorbent assay (ELISA). The patients with GD were divided into the patients with cardiovascular manifestations associated to GD (Group A, n=58) and the patients with GD not complicated by heart disease (Group B, n=60). 40 healthy subjects were included in the study (Group C, n=40). Echocardiography was performed and the differences of echocardiography parameters were compared between AT1-AA positive and negative groups in group A. Factors related to left heart enlargement were analyzed by multiple logistic regression. RESULTS: (1) The frequency of AT1-AA in Group A (52.2%, 32/58) were significantly higher than those in Group B (16.7%, 10/60) and Group C (12.5%, 5/40) (all p<0.001). (2) There were no differences in the level of TGAb, TPOAb and TRAb between AT1-AA positive and negative groups in patients with GD (all p>0.05). (3) In patients with cardiovascular manifestations of GD, the ratios between left atrial and ventricular enlargement (LAE and LVE) were significantly higher in the AT1-AA positive group than in the AT1-AA negative group (68.8% vs. 26.9%, 62.5% vs. 23.1%, all p<0.01); the frequency of atrial fibrillation differed significantly between these 2 groups (53.1% vs. 19.2%, p<0.01). (4) Regression analysis demonstrated that the positive AT1-AA and course of GD were significantly correlated to the presence of LAE and LVE. CONCLUSIONS: AT1-AA plays an important role in the pathogenesis of cardiovascular manifestations associated to GD. Especially, AT1-AA is involved in left cardiac dilatation of GD complicated by heart disease, which represents a cardio-vascular risk factor for GD patients.

Commercially available angiotensin II At2 receptor antibodies are nonspecific.

Commercially available angiotensin II At2 receptor antibodies are widely employed for receptor localization and quantification, but they have not been adequately validated. In this study, we characterized three commercially available At2 receptor antibodies: 2818-1 from Epitomics, sc-9040 from Santa Cruz Biotechnology, Inc., and AAR-012 from Alomone Labs. Using western blot analysis the immunostaining patterns observed were different for every antibody tested, and in most cases consisted of multiple immunoreactive bands. Identical immunoreactive patterns were present in wild-type and At2 receptor knockout mice not expressing the target protein. In the mouse brain, immunocytochemical studies revealed very different cellular immunoreactivity for each antibody tested. While the 2818-1 antibody reacted only with endothelial cells in small parenchymal arteries, the sc-9040 antibody reacted only with ependymal cells lining the cerebral ventricles, and the AAR-012 antibody reacted only with multiple neuronal cell bodies in the cerebral cortex. Moreover, the immunoreactivities were identical in brain tissue from wild-type or At2 receptor knockout mice. Furthermore, in both mice and rat tissue extracts, there was no correlation between the observed immunoreactivity and the presence or absence of At2 receptor binding or gene expression. We conclude that none of these commercially available At2 receptor antibodies tested met the criteria for specificity. In the absence of full antibody characterization, competitive radioligand binding and determination of mRNA expression remain the only reliable approaches to study At2 receptor expression.

Angiotensin II type I receptor agonistic autoantibody-induced apoptosis in neonatal rat cardiomyocytes is dependent on the generation of tumor necrosis factor-α.

Angiotensin II type I receptor agonistic autoantibodies (AT1-AA) are related to pre-eclampsia and hypertension and have a direct effect of stimulating the production of tumor necrosis factor-alpha (TNF-α) in the placenta. TNF-α is a known mediator of apoptosis. However, few studies have reported the role of TNF-α and its relationship within AT1-AA-induced apoptosis of cardiomyocytes. In this study, neonatal rat cardiomyocytes were treated with various concentrations of AT1-AA. The apoptosis of neonatal rat cardiomyocytes was determined using TUNEL assay and flow cytometry. The level of secreted TNF-α was measured by enzyme-linked immunosorbent assay, and caspase-3 activity was measured by a fluorogenic protease assay kit. AT1 receptor blockade and TNF inhibitor were added to determine whether they could inhibit the apoptotic effect of AT1-AA. Results showed that AT1-AA induced the apoptosis of neonatal rat cardiomyocytes in a dose-dependent and time-dependent manner. AT1-AA increased TNF secretion and caspase-3 activities. AT1 receptor blockade completely abrogated AT1-AA-induced TNF-α secretion, caspase-3 activation, and cardiomyocyte apoptosis. TNF-α receptor inhibitor significantly attenuated AT1-AA-induced neonatal rat cardiomyocyte apoptosis. AT1-AA in the plasma of pre-eclamptic patients promoted neonatal rat cardiomyocyte apoptosis through a TNF-caspase signaling pathway.

From placenta to podocyte: vascular and podocyte pathophysiology in preeclampsia.

Preeclampsia is a disorder of hypertension and proteinuria that affects 6 - 8% of normal pregnancies. Recent research has revealed many molecular mechanisms that may contribute to systemic endothelial dysfunction, glomerular capillary endotheliosis, dysregulation of the glomerular filtration apparatus, and podocyte loss. An ischemic placenta elaborates soluble FMS-like tyrosine kinase 1 (sFlt-1), a soluble receptor for vascular endothelial growth factor (VEGF). A variety of mediators, including nitric oxide, Angiotensin II receptor autoantibodies (AT1AA), and endothelin-1 may serve to maintain placental ischemia and systemic endothelial dysfunction. Endothelin-1 and decreased vascular endothelial growth factor may adversely affect overall expression and distribution of podocyte foot process proteins, leading to proteinuria. Podocyte derangements may lead to podocyte apoptosis and loss, as evidenced by the detection of live podocytes and podocyte products in the urine of preeclamptic women. In this review, we explore recent research elucidating the interactions of placenta, endothelium, and podocyte leading to the clinical syndrome of preeclampsia.

[Angiotensin receptor vaccines].

Recent clinical studies have shown that RAS inhibitors are effective not only for the prevention of end-organ damage in hypertensive patients, but also for prevention of new-onset hypertension, diabetes mellitus, and atrial fibrillation. Vaccines against the RAS have been developed since the 1950s, and a recent phase IIa placebo-controlled study has confirmed that an angiotensin vaccine causes a significant decrease in blood pressure in hypertensive patients. The results of animal experiments from our and other laboratories have suggested that vaccination against the angiotensin type 1 (AT1) receptor causes a significant decrease in blood pressure in animal models of hypertension, and also ameliorates hypertensive end-organ damage. The angiotensin receptor may therefore be an important target for the development of vaccines for the prevention of hypertension and related complications.

The use of ultralow doses of antibodies to C-terminal fragment of angiotensin II AT1 receptor (kardos) in the therapy of arterial hypertension.

Kardos monotherapy allows attaining the target levels of systolic and diastolic blood pressure in patients with high-risk and very-high-risk hypertension. We demonstrated excellent tolerability of the preparation in combination with reliable blood pressure decrease over 24 h, during day and night hours.

Expression of angiotensin II and its receptors in the normal and hypoxic amoeboid microglial cells and murine BV-2 cells.

Involvement of the local angiotensin receptor system in the central nervous system is well documented, yet its cellular localization and role in the glial cells have remained elusive. This study reports expression of angiotensin II and its receptors namely, angiotensin II receptor type 1 (AT(1)) and angiotensin II receptor type 2 (AT(2)) in the amoeboid microglial cells in the neonatal rat brain. In rats subjected to hypoxia, the amount of angiotensin II released in the corpus callosal tissue was reduced as revealed by enzyme immunoassay. Expression of AT(1) mRNA and protein was down-regulated after hypoxic exposure, but AT(2) was up-regulated. In BV-2 cells exposed to hypoxia for 4 h, expression of AT(1) mRNA was reduced but AT(2) was increased. These changes were further intensified respectively in LPS-stimulated microglia. Edaravone enhanced AT(1) expression but suppressed AT(2) expression significantly in lipopolysaccharide-stimulated cells. Neutralization of AT(2) with its antiserum significantly increased mRNA expression of tumor necrosis factor-alpha and interleukin-1beta but decreased that of transforming growth factor-beta1. In conclusion, the present results suggest that AT(1) may be linked to regulation of vasodilation for increase of blood flow in hypoxic conditions, while up-regulated expression of AT(2) may reduce inflammatory responses through suppression of proinflammatory cytokines and elimination of free radicals.

Experimental study of hypotensive effect of kardos in rats with inherited hypertension.

Kardos, a preparation containing ultralow doses of antibodies to C-terminal fragment of type 1 receptor of angiotensin II, intragastrically administered to SHR rats with hereditary hypertension for 28 days reduced blood pressure by 14.8%. Kardos was not inferior to losartan and, in contrast to the latter reduced HR by 9.4%.

[New insights in the pathophysiology of preeclampsia and potential therapeutic implications]. / Avancées récentes dans la compréhension de la physiopathologie de la prééclampsie et conséquences thérapeutiques potentielles.

Preeclampsia still represents the leading cause of feto-maternal morbi-mortality in developed countries. The reason for the persistence of such gravity results to a large extent from the lack of clear knowledge concerning the pathophysiology of this disease and consequently the lack of adequate therapy apart from placental extraction. Preeclampsia is the clinical result of a generalized maternal systemic endothelial dysfunction secondary to an abnormal placental development. The close mechanisms of the abnormal placental development remain elusive. Currently, only epidemiologic risk factors and some immuno-genetic dysfunctions have been identified to favour abnormal placentation and preeclampsia. On the other hand, the identification of two circulating anti-angiogenic proteins, the soluble-fms-like tyrosine kinase-1 and the soluble endoglin, produced in excess by the placenta during the preeclampsia, allow us now to connect clearly abnormal placentation to an endothelial dysfunction. The excessive production of these two anti-angiogenic proteins induces an endothelial dysfunction by inhibiting circulating proangiogenic factors such as the placental growth factor, the vascular endothelial growth factor but also the transforming growth factor-beta. So far, numerous placental factors have been proposed, however none has been able to induce a real typical phenotype of preeclampsia. This discovery has two potential medical impacts. Firstly, the potential possibility, in the future, to measure these surrogate markers in the blood or urine to predict the onset of preeclampsia before its clinical manifestations. Secondly the theoretical possibility to reverse the angiogenic imbalance state of preeclamspsia and consequently to correct the maternal syndrome transiently by adding exogenous proangiogenic factor.

Endothelial cells as targets of allograft rejection.

Endothelial cells harbor many antigenic determinants that may be targets for antibodies and, as such, induce acute or chronic antibody-mediated rejections. In certain cases of organ transplantation, antibodies reacting with endothelial cells, but not with ABO or human leukocyte antigens, can be observed and these are probably responsible for the rejection of the graft. The antigenic targets, however, are still poorly defined and the mechanisms of action of such antibodies would appear to be diverse, leading to the lack of a relevant in vitro assay for the detection of those antibodies. Increasing data suggest that, apart from direct alloimmune responses, autoimmune mechanisms might be triggered by alloreactivity and also play a significant role in the pathogenesis of the vascular lesions, the so-called chronic rejection, observed in organ allografts.