Influence of Antihypertensive Treatment on RAAS Peptides in Newly Diagnosed Hypertensive Patients

Intra- and postoperative relative angiotensin II deficiency in patients undergoing elective major abdominal surgery

Introduction

The classical axis of the renin-angiotensin system (RAS) makes an important contribution to blood pressure regulation under general anesthesia via the vasopressor angiotensin II (Ang II). As part of the alternative RAS, angiotensin-converting enzyme 2 (ACE2) modulates the pro-inflammatory and fibrotic effects of Ang II by processing it into the organ-protective Ang 1-7, which is cleaved to Ang 1-5 by ACE. Although the levels of ACE2 may be associated with postoperative complications, alternative RAS metabolites have never been studied perioperatively. This study was designed to investigate the perioperative kinetics and balance of both RAS axes around major abdominal surgery.

Methods

In this observational cohort study, 35 patients undergoing elective major abdominal surgery were included. Blood sampling was performed before and after induction of anesthesia, at 1 h after skin incision, at the end of surgery, and on postoperative days (POD) 1, 3, and 7. The equilibrium concentrations of Ang I-IV, Ang 1-7, and Ang 1-5 in plasma were quantified using mass spectrometry. The plasma protein levels of ACE and ACE2 were measured with ELISA.

Results

Surgery caused a rapid, transient, and primarily renin-dependent activation of both RAS axes that returned to baseline on POD 1, followed by suppression. After induction, the Ang II/Ang I ratio persistently decreased, while the ACE levels started to increase on POD 1 (all p < 0.01 versus before anesthesia). Conversely, the ACE2 levels increased on POD 3 and 7 (both p < 0.001 versus before anesthesia), when the median Ang 1-7 concentrations were unquantifiably low.

Discussion

The postoperative elevation of ACE2 may prolong the decrease of the Ang II/Ang I ratio through the increased processing of Ang II. Further clarification of the intraoperative factors leading to relative Ang II deficiency and the sources of postoperatively elevated ACE2 is warranted.

Gene Expression Analysis in T2DM and Its Associated Microvascular Diabetic Complications: Focus on Risk Factor and RAAS Pathway

Prolonged hyperglycemic conditions in type 2 diabetes mellitus (T2DM) cause pathological and functional damage to many organs and tissues, including the kidneys, retina, skin, and neuronal tissues, resulting in the development of microvascular diabetic complications. The altered renin angiotensin aldosterone system (RAAS) pathway has been reported to play an important role in the development of insulin resistance in T2DM and associated complications. The current study was carried out to evaluate the association of risk factors and altered expression of RAAS genes in T2DM patients without complications and T2DM patients with complications (retinopathy, nephropathy, and neuropathy). Four hundred and twenty subjects including 140 healthy controls, 140 T2DM patients with diabetic complications, and 140 T2DM patients without diabetic complications were included in the study. Risk factors associated with the development of T2DM and diabetic complications were evaluated. Further, expression analysis of RAAS genes (AGT, ACE, ACE2, and AGT1R) was carried out using qRTPCR in healthy controls, T2DM patients with complications, and T2DM patients without complications. Various risk factors like urban background, higher BMI, alcoholism, smoking, and family history of diabetes among others were found to be associated with the development of T2DM as well as diabetic complications. The expression level of AGT, ACE, and AGT1R was found to be upregulated whereas ACE2 was found to be downregulated in T2DM patients with complications and T2DM patients without complications as compared to controls. Altered expression of the studied genes of RAAS pathway is associated with the development of microvascular diabetic complications.

Hypertensive Heart Disease: A Narrative Review Series-Part 3: Vasculature, Biomarkers and the Matrix of Hypertensive Heart Disease

Over the last few decades, research efforts have resulted in major advances in our understanding of the pathophysiology of hypertensive heart disease (HHD). This is the third part of a three-part review series. Here, we focus on the influence of high blood pressure on the micro- and macroalterations that occur in the vasculature in HHD. We also provide an overview of circulating cardiac biomarkers that may prove useful for a better understanding of the pathophysiology, development and progression of HHD, and may play a unique role in the diagnostic and prognostic evaluation of patients with HHD, taking into account their properties showing as abnormal long before the onset of the disease. In the conclusion, we propose an updated definition of HHD and a matrix for clinical classification, which we suspect will be useful in practice, allowing an individual approach to HHD patients.

Hypertensive Heart Disease: A Narrative Review Series-Part 2: Macrostructural and Functional Abnormalities

Hypertensive heart disease (HHD) remains a major global public health concern despite the implementation of new approaches for the management of hypertensive patients. The pathological changes occurring during HHD are complex and involve the development of structural and functional cardiac abnormalities. HHD describes a broad spectrum ranging from uncontrolled hypertension and asymptomatic left ventricular hypertrophy (LVH), either a concentric or an eccentric pattern, to the final development of clinical heart failure. Pressure-overload-induced LVH is recognised as the most important predictor of heart failure and sudden death and is associated with an increased risk of cardiac arrhythmias. Cardiac arrhythmias are considered to be one of the most important comorbidities affecting hypertensive patients. This is the second part of a three-part set of review articles. Here, we focus on the macrostructural and functional abnormalities associated with chronic high pressure, their involvement in HHD pathophysiology, and their role in the progression and prognosis of HHD.

Chemical Synthesis, Safety and Efficacy of Antihypertensive Candidate Drug 221s (2,9)

Hypertension is the main risk factor of cardiovascular and cerebrovascular diseases. In this paper, a novel compound known as 221s (2,9), which includes tanshinol, borneol and a mother nucleus of ACEI, was synthesized by condensation esterification, deprotection, amidation, deprotection, and amidation, with borneol as the initial raw material, using the strategy of combinatorial molecular chemistry. The structure of the compound was confirmed by ¹H NMR, ¹³C NMR, and high-resolution mass spectrometry, with a purity of more than 99.5%. The compound 221s (2,9) can significantly reduce the systolic and diastolic blood pressure of SHR rats by about 50 mmHg and 35 mmHg after 4 weeks of administration. The antihypertensive effect of 221s (2,9) is equivalent to that of captopril. The use of 221s (2,9) can reduce the content of Ren, Ang II and ACE in the serum of SHR rats, inhibit the RAAS and enhance the vascular endothelial function by upregulating the level of NO. Pathological studies in this area have shown that high dosage of 221s (2,9) can notably protect myocardial fibrosis in rats and reduce the degeneration and necrosis of myocardial fibers, inflammatory cell infiltration, and proliferation of fibrous tissue in the heart of rat. Therefore, the existing work provided a foundation for preclinical research and follow-up clinical research of 221s (2,9) as a new drug.

Poor Performance of Angiotensin II Enzyme-Linked Immuno-Sorbent Assays in Mostly Hypertensive Cohort Routinely Screened for Primary Aldosteronism

Primary aldosteronism (PA) is the most common, but broadly underdiagnosed, form of hormonal hypertension. To improve screening procedures, current biochemical approaches aim to determine newly appreciated angiotensin II (Ang II) and calculate the aldosterone-to-angiotensin II ratio (AA2R). Thus, the aim of this study was to assess the diagnostic performance of these screening tests in comparison to the aldosterone-to-direct renin ratio (ADRR), which is routinely used. Cheap and available ELISA was used for Ang II measurement. To our knowledge, this is the first study of this laboratory method’s usage in PA. The study cohort included 20 PA patients and 80 controls. Ang II concentrations were comparable between PA and non-PA patients (773.5 vs. 873.2 pg/mL, p = 0.23, respectively). The AA2R was statistically significantly higher in PA group when compared with non-PA (0.024 vs. 0.012 ng/dL/pg/mL, p < 0.001). However, the diagnostic performance of the AA2R was significantly worse than that of the ADRR (AUROC 0.754 vs. 0.939, p < 0.01). The sensitivity and specificity of the AA2R were 70% and 76.2%, respectively. Thus, the AA2R was not effective as a screening tool for PA. Our data provide important arguments in the discussion on the unsatisfactory accuracy of renin−angiotensin system evaluation by recently repeatedly used ELISA tests.

The Renin-Angiotensin System as a Component of Biotrauma in Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a major concern in critical care medicine with a high mortality of over 30%. Injury to the lungs is caused not only by underlying pathological conditions such as pneumonia, sepsis, or trauma, but also by ventilator-induced lung injury (VILI) resulting from high positive pressure levels and a high inspiratory oxygen fraction. Apart from mechanical factors that stress the lungs with a specific physical power and cause volutrauma and barotrauma, it is increasingly recognized that lung injury is further aggravated by biological mediators. The COVID-19 pandemic has led to increased interest in the role of the renin-angiotensin system (RAS) in the context of ARDS, as the RAS enzyme angiotensin-converting enzyme 2 serves as the primary cell entry receptor for severe acute respiratory syndrome (SARS) coronavirus (CoV)-2. Even before this pandemic, studies have documented the involvement of the RAS in VILI and its dysregulation in clinical ARDS. In recent years, analytical tools for RAS investigation have made major advances based on the optimized precision and detail of mass spectrometry. Given that many clinical trials with pharmacological interventions in ARDS were negative, RAS-modifying drugs may represent an interesting starting point for novel therapeutic approaches. Results from animal models have highlighted the potential of RAS-modifying drugs to prevent VILI or treat ARDS. While these drugs have beneficial pulmonary effects, the best targets and application forms for intervention still have to be determined to avoid negative effects on the circulation in clinical settings.