Newly developed radioimmunoassay for Human Angiotensin-(1-12) measurements in plasma and urine

Progress in Procalcitonin Detection Based on Immunoassay

Procalcitonin (PCT) serves as a crucial biomarker utilized in diverse clinical contexts, including sepsis diagnosis and emergency departments. Its applications extend to identifying pathogens, assessing infection severity, guiding drug administration, and implementing theranostic strategies. However, current clinical deployed methods cannot meet the needs for accurate or real-time quantitative monitoring of PCT. This review aims to introduce these emerging PCT immunoassay technologies, focusing on analyzing their advantages in improving detection performances, such as easy operation and high precision. The fundamental principles and characteristics of state-of-the-art methods are first introduced, including chemiluminescence, immunofluorescence, latex-enhanced turbidity, enzyme-linked immunosorbent, colloidal gold immunochromatography, and radioimmunoassay. Then, improved methods using new materials and new technologies are briefly described, for instance, the combination with responsive nanomaterials, Raman spectroscopy, and digital microfluidics. Finally, the detection performance parameters of these methods and the clinical importance of PCT detection are also discussed.

Chymase-independent vascular Ang-(1-12)/Ang II pathway and TXA2 generation are involved in endothelial dysfunction in the murine model of heart failure

The angiotensin (Ang)-(1-12)/Ang II pathway contributes to cardiac pathology. However, its involvement in the development of peripheral endothelial dysfunction associated with heart failure (HF) remains unknown. Therefore, this study aimed to characterise the effect of exogenous Ang-(1-12) and its conversion to Ang II on endothelial function using the murine model of HF (Tgαq*44 mice), focusing on the role of chymase and vascular-derived thromboxane A2 (TXA2). Ex vivo myographic assessments of isolated aorta showed impaired endothelium-dependent vasodilation in late-stage HF in 12-month-old Tgαq*44 mice. However, endothelium-dependent vasodilation was fully preserved in the early stage of HF in 4-month-old Tgαq*44 mice and 4- and 12-month-old FVB control mice. Ang-(1-12) impaired endothelium-dependent vasodilation in 4- and 12-month-old Tgαq*44 mice, that was associated with increased Ang II production. The chymase inhibitor chymostatin did not inhibit this response. Interestingly, TXA2 production reflected by TXB2 measurement was upregulated in response to Ang-(1-12) and Ang II in aortic rings isolated from 12-month-old Tgαq*44 mice but not from 4-month-old Tgαq*44 mice or age-matched FVB mice. Furthermore, in vivo magnetic resonance imaging showed that Ang-(1-12) impaired endothelium-dependent vasodilation in the aorta of Tgαq*44 mice and FVB mice. However, this response was inhibited by angiotensin I converting enzyme (ACE) inhibitor; perindopril, angiotensin II receptor type 1 (AT1) antagonist; losartan and TXA2 receptor (TP) antagonist-picotamide in 12-month-old-Tgαq*44 mice only. In conclusion, the chymase-independent vascular Ang-(1-12)/Ang II pathway and subsequent TXA2 overactivity contribute to systemic endothelial dysfunction in the late stage of HF in Tgαq*44 mice. Therefore, the vascular TXA2 receptor represents a pharmacotherapeutic target to improve peripheral endothelial dysfunction in chronic HF.

Chymase in Plasma and Urine Extracellular Vesicles: Novel Biomarkers for Primary Hypertension

BACKGROUND

Extracellular vesicles (EVs) have emerged as a promising liquid biopsy for various diseases. For the first time, using plasma and urinary EVs, we assessed the activity of renin-angiotensin system (RAS), a central regulator of renal, cardiac, and vascular physiology, in patients with control (Group I) or uncontrolled (Group II) primary hypertension.

METHODS

EVs were isolated from 34 patients with history of hypertension, and characterized for size and concentration by nanoparticle tracking analyses, exosomal biomarkers by immunogold labeling coupled with transmission electron microscopy, flow cytometry and immunoblotting. EVs were analyzed for the hydrolytic activity of chymase, angiotensin converting enzyme (ACE), ACE2, and neprilysin (NEP) by HPLC.

RESULTS

Plasma and urinary EVs were enriched for small EVs and expressed exosomal markers (CD63, CD9, and CD81). The size of urinary EVs (but not plasma EVs) was significantly larger in Group II compared to Group I. Differential activity of RAS enzymes was observed, with significantly higher chymase activity compared to ACE, ACE2, and NEP in plasma EVs. Similarly, urinary EVs exhibited higher chymase and NEP activity compared to ACE and ACE2 activity. Importantly, compared to Group I, significantly higher chymase activity was observed in urinary EVs (p = 0.03) from Group II, while no significant difference in activity was observed for other RAS enzymes.

CONCLUSIONS

Bioactive RAS enzymes are present in plasma and urinary EVs. Detecting chymase in plasma and urinary EVs uncovers a novel mechanism of angiotensin II-forming enzyme and could also mediate cell-cell communication and modulate signaling pathways in recipient cells.

GRAPHICAL ABSTRACT

Impedimetric aptasensor based on MOF based composite for measuring of carcinoembryonic antigen as a tumor biomarker

In this research, gold nanoparticle (GNPs)-modified metal-organic framework/reduced graphene oxide (MOF(801)/rGO) hybrid was employed to design a new aptasensor for carcinoembryonic antigen (CEA) quantification in biological sample. The sensing ability of the electrode for CEA biomarker was examined with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry procedures. Besides, CEA was electrochemically quantified by the EIS method. With respect to the high surface-to-volume ratio of MOF(801) and the good electron transfer ability of rGO, the proposed sensor displayed notable sensitivity and reliability in the CEA analysis. The derived electrode showed an appreciable detection limit of 0.8 pg L-1 using EIS protocol. In addition, the present aptasensor revealed diverse advantages including anti-interference property, wide linear range (0.0025-0.25 ng L-1), convenience and high efficiency toward CEA quantification. More importantly, the performance of the suggested assay remains unchanged in analysis of CEA in body fluids. The established assay demonstrates that the suggested biosensor is a promising device in clinical diagnosis.

A Liquid Biopsy-Based Approach to Isolate and Characterize Adipose Tissue-Derived Extracellular Vesicles from Blood

Obesity is a major risk factor for multiple chronic diseases. Anthropometric and imaging approaches are primarily used to assess adiposity, and there is a dearth of techniques to determine the changes in adipose tissue (AT) at the molecular level. Extracellular vesicles (EVs) have emerged as a novel and less invasive source of biomarkers for various pathologies. Furthermore, the possibility of enriching cell or tissue-specific EVs from the biofluids based on their unique surface markers has led to classifying these vesicles as "liquid biopsies", offering valuable molecular information on hard-to-access tissues. Here, we isolated small EVs from AT (sEVAT) of lean and diet-induced obese (DIO) mice, identified unique surface proteins on sEVAT by surface shaving followed by mass spectrometry, and developed a signature of five unique proteins. Using this signature, we pulled out sEVAT from the blood of mice and validated the specificity of isolated sEVAT by measuring the expression of adiponectin, 38 adipokines on an array, and several adipose tissue-related miRNAs. Furthermore, we provided evidence of sEV applicability in disease prediction by characterizing sEVAT from the blood of lean and DIO mice. Interestingly, sEVAT-DIO cargo showed a stronger pro-inflammatory effect on THP1 monocytes compared to sEVAT-Lean and a significant increase in obesity-associated miRNA expression. Equally important, sEVAT cargo revealed an obesity-associated aberrant amino acid metabolism that was subsequently validated in the corresponding AT. Lastly, we show a significant increase in inflammation-related molecules in sEVAT isolated from the blood of nondiabetic obese (>30 kg/m2) individuals. Overall, the present study offers a less-invasive approach to characterize AT.

Internalization of Angiotensin-(1-12) in Adult Retinal Pigment Epithelial-19 Cells

Purpose: Angiotensin-(1-12) [Ang-(1-12)] serves as a primary substrate to generate angiotensin II (Ang II) by angiotensin-converting enzyme and/or chymase suggests it may be an unrecognized source of Ang II-mediated microvascular complication in hypertension-mediated retinopathy. We investigated Ang-(1-12) expression and internalization in adult retinal pigment epithelial-19 (ARPE-19) cultured cells. We performed the internalization of Ang-(1-12) in ARPE-19 cells in the presence of a highly specific monoclonal antibody (mAb) developed against the C-terminal end of the Ang-(1-12) sequence. Methods: All experiments were performed in confluent ARPE-19 cells (passage 28-35). We employed high-performance liquid chromatography to purify radiolabeled, 125I-Ang-(1-12) and immuno-neutralization with Ang-(1-12) mAb to demonstrate Ang-(1-12)'s internalization in ARPE-19 cells. Internalization was also demonstrated by immunofluorescence (IF) method. Results: These procedures revealed internalization of an intact 125I-Ang-(1-12) in ARPE-19 cells. A significant reduction (∼53%, P < 0.0001) in 125I-Ang-(1-12) internalization was detected in APRE-19 cells in the presence of the mAb. IF staining experiments further confirms internalization of Ang-(1-12) into the cells from the extracellular culture medium. No endogenous expression was detected in the ARPE-19 cells. An increased intensity of IF staining was detected in cells exposed to 1.0 μM Ang-(1-12) compared with 0.1 μM. Furthermore, we found hydrolysis of Ang-(1-12) into Ang II by ARPE-19 cells' plasma membranes. Conclusions: Intact Ang-(1-12) peptide is internalized from the extracellular spaces in ARPE-19 cells and metabolized into Ang II. The finding that a selective mAb blocks cellular internalization of Ang-(1-12) suggests alternate therapeutic approaches to prevent/reduce the RPE cells Ang II burden.

Impact of early pericardial fluid chymase activation after cardiac surgery

Introduction

Chymase is a highly destructive serine protease rapidly neutralized in the circulation by protease inhibitors. Here we test whether pericardial fluid (PCF) chymase activation and other inflammatory biomarkers determine intensive care unit length of stay, and explore mechanisms of chymase delivery by extracellular vesicles to the heart.

Methods

PCF was collected from adult patients (17 on-pump; 13 off-pump) 4 h after cardiac surgery. Extracellular vesicles (EVs) containing chymase were injected into Sprague-Dawley rats to test for their ability to deliver chymase to the heart.

Results

The mean intensive care unit (ICU) stay and mean total length of stay was 2.17 ± 3.8 days and 6.41 ± 1.3 days respectively. Chymase activity and 32 inflammatory markers did not differ in on-pump vs. off-pump cardiac surgery. Society of Thoracic Surgeons Predicted Risk of Morbidity and Mortality Score (STS-PROM), 4-hour post-surgery PCF chymase activity and C-X-C motif chemokine ligand 6 (CXCL6) were all independent predictors of ICU and total hospital length of stay by univariate analysis. Mass spectrometry of baseline PCF shows the presence of serine protease inhibitors that neutralize chymase activity. The compartmentalization of chymase within and on the surface of PCF EVs was visualized by immunogold labeling and transmission electron microscopy. A chymase inhibitor prevented EV chymase activity (0.28 fmol/mg/min vs. 14.14 fmol/mg/min). Intravenous injection of PCF EVs obtained 24 h after surgery into Sprague Dawley rats shows diffuse human chymase uptake in the heart with extensive cardiomyocyte damage 4 h after injection.

Discussion

Early postoperative PCF chymase activation underscores its potential role in cardiac damage soon after on- or off-pump cardiac surgery. In addition, chymase in extracellular vesicles provides a protected delivery mechanism from neutralization by circulating serine protease inhibitors.

Does the Naked Emperor Parable Apply to Current Perceptions of the Contribution of Renin Angiotensin System Inhibition in Hypertension?

PURPOSE OF REVIEW

To address contemporary hypertension challenges, a critical reexamination of therapeutic accomplishments using angiotensin converting enzyme inhibitors and angiotensin II receptor blockers, and a greater appreciation of evidence-based shortcomings from randomized clinical trials are fundamental in accelerating future progress.

RECENT FINDINGS

Medications targeting angiotensin II mechanism of action are essential for managing primary hypertension, type 2 diabetes, heart failure, and chronic kidney disease. While the ability of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers to control blood pressure is undisputed, practitioners, hypertension specialists, and researchers hold low awareness of these drugs' limitations in preventing or reducing the risk of cardiovascular events. Biases in interpreting gained knowledge from data obtained in randomized clinical trials include a pervasive emphasis on using relative risk reduction over absolute risk reduction. Furthermore, recommendations for clinical practice in international hypertension guidelines fail to address the significance of a residual risk several orders of magnitude greater than the benefits. We analyze the limitations of the clinical trials that have led to current recommended treatment guidelines. We define and quantify the magnitude of the residual risk in published hypertension trials and explore how activation of alternate compensatory bioprocessing components within the renin angiotensin system bypass the ability of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers to achieve a significant reduction in total and cardiovascular deaths. We complete this presentation by outlining the current incipient but promising potential of immunotherapy to block angiotensin II pathology alone or possibly in combination with other antihypertensive drugs. A full appreciation of the magnitude of the residual risk associated with current renin angiotensin system-based therapies constitutes a vital underpinning for seeking new molecular approaches to halt or even reverse the cardiovascular complications of primary hypertension and encourage investigating a new generation of ACE inhibitors and ARBs with increased capacity to reach the intracellular compartments at which Ang II can be generated.

Immunoneutralization of human angiotensin-(1-12) with a monoclonal antibody in a humanized model of hypertension

We engineered a monoclonal antibody (mAb) against the human C-terminus of angiotensin-(1-12) [h-Ang-(1-12)] and performed a biochemical characterization in concert with direct in vivo and ex vivo (carotid artery strips) assessments of h-Ang-(1-12) vasoconstrictor activity in 78 (36 females) transgenic rats expressing the human angiotensinogen gene [TGR(hAGT)L1623] and 26 (10 female) Sprague Dawley (SD) controls. The mAb shows high specificity in neutralizing angiotensin II formation from h-Ang-(1-12) and did not cross-react with human and rat angiotensins. Changes in arterial pressure and heart rate in Inactin® hydrate anesthetized rats were measured before and after h-Ang-(1-12) injections [dose range: 75-300 pmol/kg i.v.] prior to and 30-60 minutes after administration of the h-Ang-(1-12) mAb. Neutralization of circulating Ang-(1-12) inhibited the pressor action of h-Ang-(1-12), prevented Ang-(1-12) constrictor responses in carotid artery rings in both SD and TGR(hAGT)L1623 rats, and caused a fall in the arterial pressure of male and female transgenic rats. The Ang-(1-12) mAb did not affect the response of comparable dose-related pressor responses to Ang II, pre-immune IgG, or the rat sequence of Ang-(1-12). This h-Ang-(1-12) mAb can effectively suppress the pressor actions of the substrate in the circulation of hypertensive rats or in carotid artery strips from both SD and transgenic rats. The demonstration that this Ang-(1-12) mAb by itself, induced a fall in arterial pressure in transgenic hypertensive rats supports further exploring the potential abilities of Ang-(1-12) mAb in the treatment of hypertension.

Robust analysis of angiotensin peptides in human plasma: Column switching-parallel LC/ESI-SRM/MS without adsorption or enzymatic decomposition

Angiotensin (Ang) peptides are the main effectors of the renin-angiotensin system (RAS) regulating diverse physiological conditions and are involved in renal and vascular diseases. Currently, quantitative analyses of Ang peptides in human plasma mainly rely on radioimmunoassay-based methods whose reported levels are quite divergent. Analyses are further complicated by the potential of Ang peptides to bind to solid surfaces, to be enzymatically decomposed during sample preparation, and to undergo post-translational modifications. A column switching-parallel LC/ESI-SRM/MS method has been developed for seven Ang peptides (Ang I, Ang II, Ang III, Ang IV, Ang 1-9, Ang 1-7, and Ang A) in human plasma. Aqueous acetonitrile (5%) containing 50 mM arginine (Arg) as a dissolving solution and a combination of protease inhibitors with formic acid were used to prevent adsorption and enzymatic degradation, respectively. Plasma samples were simply deproteinized with acetonitrile followed by clean-up with an on-line trap column via column-switching. Stable isotope dilution with [¹³C₅,¹⁵N₁-Val]-Ang peptides as internal standards was employed for quantitative analysis. The current methodology has been successfully applied to determine the plasma levels of Ang peptides in healthy participants, suggesting future applicability to studies of various diseases related to RAS.