Renal effects of dual renin-angiotensin-aldosterone system blockade in patients with diabetic nephropathy

Endothelial NOX5 Obliterates the Reno-Protective Effect of Nox4 Deletion by Promoting Renal Fibrosis via Activation of EMT and ROS-Sensitive Pathways in Diabetes

Chronic hyperglycemia induces intrarenal oxidative stress due to the excessive production of reactive oxygen species (ROS), leading to a cascade of events that contribute to the development and progression of diabetic kidney disease (DKD). NOX5, a pro-oxidant NADPH oxidase isoform, has been identified as a significant contributor to renal ROS in humans. Elevated levels of renal ROS contribute to endothelial cell dysfunction and associated inflammation, causing increased endothelial permeability, which can disrupt the renal ecosystem, leading to progressive albuminuria and renal fibrosis in DKD. This study specifically examines the contribution of endothelial cell-specific human NOX5 expression in renal pathology in a transgenic mouse model of DKD. This study additionally compares NOX5 with the previously characterized NADPH oxidase, NOX4, in terms of their relative roles in DKD. Regardless of NOX4 pathway, this study found that endothelial cell-specific expression of NOX5 exacerbates renal injury, albuminuria and fibrosis. This is attributed to the activation of the endothelial mesenchymal transition (EMT) pathway via enhanced ROS formation and the modulation of redox-sensitive factors. These findings underscore the potential therapeutic significance of NOX5 inhibition in human DKD. The study proposes that inhibiting NOX5 could be a promising approach for mitigating the progression of DKD and strengthens the case for the development of NOX5-specific inhibitors as a potential therapeutic intervention.

Management of hypertension and renin-angiotensin-aldosterone system blockade in adults with diabetic kidney disease: Association of British Clinical Diabetologists and the Renal Association UK guideline update 2021

People with type 1 and type 2 diabetes are at risk of developing progressive chronic kidney disease (CKD) and end-stage kidney failure. Hypertension is a major, reversible risk factor in people with diabetes for development of albuminuria, impaired kidney function, end-stage kidney disease and cardiovascular disease. Blood pressure control has been shown to be beneficial in people with diabetes in slowing progression of kidney disease and reducing cardiovascular events. However, randomised controlled trial evidence differs in type 1 and type 2 diabetes and different stages of CKD in terms of target blood pressure. Activation of the renin-angiotensin-aldosterone system (RAAS) is an important mechanism for the development and progression of CKD and cardiovascular disease. Randomised trials demonstrate that RAAS blockade is effective in preventing/ slowing progression of CKD and reducing cardiovascular events in people with type 1 and type 2 diabetes, albeit differently according to the stage of CKD. Emerging therapy with sodium glucose cotransporter-2 (SGLT-2) inhibitors, non-steroidal selective mineralocorticoid antagonists and endothelin-A receptor antagonists have been shown in randomised trials to lower blood pressure and further reduce the risk of progression of CKD and cardiovascular disease in people with type 2 diabetes. This guideline reviews the current evidence and makes recommendations about blood pressure control and the use of RAAS-blocking agents in different stages of CKD in people with both type 1 and type 2 diabetes.

Combination use of angiotensin converting enzyme inhibitors and angiotensin receptor blockers in diabetic kidney disease

Angiotensin converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARB) have played a major role in slowing the progression of diabetic kidney disease, since they lower urine protein levels, lower blood pressure, and slow progression. Studies have suggested that the combination of ACE-I and ARB offered greater benefits for patients with diabetic kidney disease. In 2008, the large ONTARGET study reported no benefit with combination therapy, as compared with monotherapy. This study has changed practice patterns, but few patients in this study had diabetic kidney disease. In this review, the data in favor of the combination use of these agents in patients with diabetic kidney disease and data against the combination are reviewed. At this time, there is little support for using the combination in diabetic patients with no kidney disease or early stage diabetic kidney disease. But there are patients who may benefit from combination use.

The association between circulating angiotensin-converting enzyme and cardiovascular risk in the elderly: a cross-sectional study

INTRODUCTION

A polymorphism in the angiotensin-converting enzyme gene (ACE I/D polymorphism) has been associated with increased risk for cardiovascular disease (CVD). This polymorphism affects the level of circulating ACE, but there is great individual variation, even between those with the same genotype. Few previous studies have investigated the link between circulating ACE and cardiovascular risk. The aim of this study was to investigate this association, and to examine the relationship between ACE level, ACE genotype and CVD.

MATERIALS AND METHODS

The study population consisted of 322 men and 350 women aged 69-87. Plasma ACE level was determined using enzyme-linked immunosorbent assay (ELISA), and ACE genotype was analysed using PCR followed by gel electrophoresis.

RESULTS

In men, ACE levels increased with increasing number of cardiovascular risk factors (p = 0.003). There was a significant association in men between increased ACE level and both diabetes (p = 0.007) and smoking (p = 0.037).

CONCLUSIONS

This study shows that cardiovascular risk factors (such as smoking and diabetes) are associated with higher levels of circulating ACE in men. High ACE levels may represent one of the cellular mechanisms involved in producing the vascular damage associated with cardiovascular risk factors.

Renin-angiotensin-aldosterone system blockade for cardiovascular diseases: current status

Activation of the renin-angiotensin-aldosterone system (RAAS) results in vasoconstriction, muscular (vascular and cardiac) hypertrophy and fibrosis. Established arterial stiffness and cardiac dysfunction are key factors contributing to subsequent cardiovascular and renal complications. Blockade of RAAS has been shown to be beneficial in patients with hypertension, acute myocardial infarction, chronic systolic heart failure, stroke and diabetic renal disease. An aggressive approach for more extensive RAAS blockade with combination of two commonly used RAAS blockers [ACE inhibitors (ACEIs) and angiotensin receptor blockers (ARBs)] yielded conflicting results in different patient populations. Combination therapy is also associated with more side effects, in particular hypotension, hyperkalaemia and renal impairment. Recently published ONTARGET study showed ACEI/ARB combination therapy was associated with more adverse effects without any increase in benefit. The Canadian Hypertension Education Program responded with a new warning: 'Do not use ACEI and ARB in combination'. However, the European Society of Cardiology in their updated heart failure treatment guidelines still recommended ACEI/ARB combo as a viable option. This apparent inconsistency among guidelines generates debate as to which approach of RAAS inhibition is the best. The current paper reviews the latest evidence of isolated ACEI or ARB use and their combination in cardiovascular diseases, and makes recommendations for their prescriptions in specific patient populations.

Direct renin inhibitors: ONTARGET for success?

Direct renin inhibitors are the first new class of antihypertensive to emerge since angiotensin II receptor blockers. We discuss their reno- and cardioprotective potential, based on extrapolation from animal models and phase three trials that are currently ongoing. This paper reviews the potential benefits of direct renin inhibitors (DRIs), the only new anti-hypertensive class developed in the last decade, as compared to pre-existing classes of drug inhibiting more downstream, such as Angiotensin Converting Enzyme inhibitors (ACEI), Angiotensin 2 Receptor Blockers (ARBS).