Immunolocalization of the AT-1R Ang II Receptor in Human Kidney Cancer

This study aimed to evaluate AT1-R expression in normal and cancerous human kidneys, how these expressions are modified, and AT1-R functionality. AT-1R mRNA expression, determined by real-time PCR, was detected in all samples. AT-1R mRNA increased in well-differentiated cancer (G1, p < 0.01) and decreased 2.9-fold in undifferentiated cancer (G4, p < 0.001) compared with normal kidney tissues. Immunocytochemistry analysis showed that the AT-1R was expressed in the normal tubular epithelium. The glomerulus was also immunoreactive, and as expected, the smooth muscle cells of the vessel walls also expressed the receptor. A total of 35 out of 42 tumors were AT-1R positive, with the cell tumors showing varying numbers of immunoreactive cells, which were stained in a diffuse cytoplasmic and membranous pattern. Computer-assisted counting of the stained tumor cells showed that the number of AT-1R-positive cells increased in the well-differentiated cancers. The functionality of AT-1R was assessed in primary cultures of kidney epithelial cells obtained from three G3 kidney cancer tissues and corresponding histologically proven non-malignant tissue adjacent to the tumor. Indeed, Ang II stimulated, in a dose-dependent manner, the 24 h proliferation of normal kidney cells and cancer cells in the primary culture and phosphorylated extracellular regulated kinases 1 and 2. In conclusion, Ang II may be involved in the growth or function of neoplastic kidney tissue.

Impact of COVID-19 infection on the cardiovascular system: An evidence-based analysis of risk factors and outcomes

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as COVID-19, emerged in late 2019 in Wuhan, China. The World Health Organization declared the virus a pandemic on March 11, 2020. Disease progression from COVID-19 infection has shown significant symptom manifestations within organ systems beyond the respiratory system. The literature has shown increasing evidence of cardiovascular involvement during disease course and an associated increase in mortality among infected patients. Although the understanding of this novel virus is continually evolving, it is currently proposed that the mechanism by which the SARS-CoV-2 virus contributes to cardiovascular manifestations involves the ACE2 transmembrane protein. The protein ACE2 is highly expressed in blood vessel pericytes, and infection can result in microvascular dysfunction and subsequent acute coronary syndromes. Complications involving the cardiovascular system include myocardial infarction, arrhythmias, shock, and heart failure. In this evidence-based review, we discuss risk factors of cardiovascular involvement in COVID-19 infection, pathophysiology of COVID-19-related cardiovascular infection, and injury, COVID-19 effects on the cardiovascular system and corresponding treatments, and hematologic effects of COVID-19 and COVID-19 in heart transplant patients. Clinicians managing COVID-19 patients should appreciate the potential cardiovascular effects related to the disease process.

Valsartan prevents neointimal hyperplasia after carotid artery stenting by suppressing endothelial cell injuries

OBJECTIVES

Restenosis or neointimal hyperplasia remains an important complication after carotid artery stenting (CAS) for carotid artery stenosis. The purpose of this study was to examine if an anti-hypertensive drug, angiotensin receptor blocker (ARB), prevents post-CAS neointimal hyperplasia during the first 1-year period after CAS, and to clarify the possible mechanisms.

METHODS

Hypertension had been treated with a calcium channel blocker (CCB) and/or an ARB, valsartan, by the preference of the neurosurgeon in charge in our department. At admission to perform CAS, patients were assigned to normotensive, valsartan (hypertensive patients treated with valsartan with/without any kind of CCBs), and non-valsartan (hypertensive patients treated with any kind of CCBs without ARBs) groups. Post-CAS neointimal hyperplasia was evaluated by carotid duplex ultrasound imaging in terms of intima-media thickening (IMT), which was performed at pre-CAS and at 90, 180, 270, and 360 days post-CAS. Biomarkers of oxidative stress (8-hydroxy-2'-deoxyguanosine), inflammation (C-reactive protein, tenascin-C) and endothelial cell injury (von Willebrand factor [vWF] antigen) were measured at pre-CAS and at 1, 7, and 180 days post-CAS.

RESULTS

The non-valsartan group (n  =  8) had a higher incidence of maximum in-stent IMT ≧ 1.1 mm compared with the normotensive group (n  =  6). Valsartan (n  =  9) significantly suppressed plasma vWF levels at 7 days post-CAS and decreased the incidence of maximum in-stent IMT ≧ 1.1 mm compared with the non-valsartan group, although clinical parameters were similar between the two groups. Other biomarkers were not significantly different among the three groups.

CONCLUSIONS

These findings suggest that valsartan may prevent post-CAS neointimal hyperplasia possibly by suppressing endothelial cell injury.

The role of angiotensin receptor blockers in reducing the risk of cardiovascular disease

New approaches to the definition and treatment of hypertension have increased emphasis on reducing overall cardiovascular risk and on targeting the underlying mechanisms of cardiovascular disease. During the past several decades, renin-angiotensin-aldosterone system (RAAS) activation has emerged as an important factor in the pathophysiology of endothelial dysfunction and cardiovascular disease (CVD). Angiotensin-converting enzyme inhibitors (ACEIs) have well-established efficacy for treating CVD, but their use may be limited by intolerable side effects, such as cough and angioedema. Angiotensin II receptor blockers (ARBs), a different class of RAAS inhibitors, are considered a viable alternative to ACEIs. Clinical trials have further elucidated the role of ARBs in CVD. This article reviews the mechanism of action of ARBs and selected clinical trials of ARBs in CVD.

Angiotensin II type II receptor deficiency accelerates the development of nephropathy in type I diabetes via oxidative stress and ACE2

Since the functional role(s) of angiotensin II (Ang II) type II receptor (AT₂R) in type I diabetes is unknown, we hypothesized that AT₂R is involved in decreasing the effects of type I diabetes on the kidneys. We induced diabetes with low-dose streptozotocin (STZ) in both AT₂R knockout (AT₂RKO) and wild-type (WT) male mice aged 12 weeks and followed them for 4 weeks. Three subgroups nondiabetic, diabetic, and insulin-treated diabetic (Rx insulin implant) were studied. Systolic blood pressure (SBP), physiological parameters, glomerular filtration rate (GFR), renal morphology, gene expression, and apoptosis were assessed. After 4 weeks of diabetes, compared to WT controls, AT₂RKO mice clearly developed features of early diabetic nephropathy (DN), such as renal hypertrophy, tubular apoptosis, and progressive extracellular matrix (ECM) protein accumulation as well as increased GFR. AT₂RKO mice presented hypertension unaffected by diabetes. Renal oxidative stress (measured as heme oxygenase 1 (HO-1) gene expression and reactive oxygen species (ROS) generation) and intrarenal renin angiotensin system components, such as angiotensinogen (Agt), AT₁R, and angiotensin-converting enzyme (ACE) gene expression, were augmented whereas angiotensin-converting enzyme2 (ACE2) gene expression was decreased in renal proximal tubules (RPTs) of AT₂RKO mice. The renal changes noted above were significantly enhanced in diabetic AT₂RKO mice but partially attenuated in insulin-treated diabetic WT and AT₂RKO mice. In conclusion, AT₂R deficiency accelerates the development of DN, which appears to be mediated, at least in part, via heightened oxidative stress and ACE/ACE2 ratio in RPTs.

Evidence for benefits of angiotensin receptor blockade beyond blood pressure control

Elevated levels of angiotensin II result in oxidative stress and endothelial dysfunction, which initiate atherogenic pathologic processes that are important in cardiovascular disease development. Angiotensin II induces its deleterious effects primarily through the type 1 receptor; these effects are inhibited by angiotensin II receptor blockers (ARBs) directly at the receptor level. Angiotensin II may potentiate protective mechanisms through stimulation of the type 2 receptor, which is not blocked by ARBs. Accumulating data suggest that blockade of angiotensin II production or activity provides vascular and cardioprotective benefits, such as reduction of atrial fibrillation, acute myocardial infarction, and heart failure events. Moreover, blockade of the renin-angiotensin system has been shown to offer renal protection in subjects with and without diabetes mellitus and to reduce the risk of new-onset diabetes.