Aliskiren and perindopril reduce the levels of transforming growth factor-β in patients with non-diabetic kidney disease

Sodium-glucose cotransporter inhibitors and kidney fibrosis: review of the current evidence and related mechanisms

Sodium-glucose cotransporter inhibitors (SGLT2i) are a new class of anti-diabetic drugs that have beneficial cardiovascular and renal effects. These drugs decrease proximal tubular glucose reabsorption and decrease blood glucose levels as a main anti-diabetic action. Furthermore, SGLT2i decreases glomerular hyperfiltration by a tubuloglomerular feedback mechanism. However, the renal benefits of these agents are independent of glucose-lowering and hemodynamic factors, and SGLT2i also impacts the kidney structure including kidney fibrosis. Renal fibrosis is a common pathway and pathological marker of virtually every type of chronic kidney disease (CKD), and amelioration of renal fibrosis is of utmost importance to reduce the progression of CKD. Recent studies have shown that SGLT2i impact many cellular processes including inflammation, hypoxia, oxidative stress, metabolic functions, and renin-angiotensin system (RAS) which all are related with kidney fibrosis. Indeed, most but not all studies showed that renal fibrosis was ameliorated by SGLT2i through the reduction of inflammation, hypoxia, oxidative stress, and RAS activation. In addition, less known effects on SGLT2i on klotho expression, capillary rarefaction, signal transducer and activator of transcription signaling and peptidylprolyl cis/trans isomerase (Pin1) levels may partly explain the anti-fibrotic effects of SGLT2i in kidneys. It is important to remember that some studies have not shown any beneficial effects of SGLT2i on kidney fibrosis. Given this background, in the current review, we have summarized the studies and pathophysiologic aspects of SGL2 inhibition on renal fibrosis in various CKD models and tried to explain the potential reasons for contrasting findings.

Immunomodulatory properties of antihypertensive drugs and digitalis glycosides

INTRODUCTION

The role of chronic inflammatory process in the pathogenesis or exacerbation of hypertension has been already acknowledged.

AREAS COVERED

Therefore, one can speculate that hypotensive drugs may exert some of their therapeutic effects due to immunomodulatory properties. So far, this assumption has been tested in different studies, and the resulting knowledge is summarized in the current review article that is dedicated to different groups of antihypertensives, namely calcium channel blockers, beta blockers, as well as other less commonly used medications, such as hydralazine, agonists of alfa-2 receptor, diazoxide, doxazosin, aliskiren, and sodium nitroprusside. Articles were found in the Pubmed database by entering the name of a specific drug (or group of drugs) together with the words: immunology, cellular response, humoral response, inflammation, interleukin. The 2000-2021 range was used to search for all drugs except propranolol (1980-2021) and calcium blockers (1990-2021).

EXPERT OPINION

Observed decrease in serum/plasma concentration of proinflammatory cytokines, and CRP along with lower expression of adhesion molecules on immune cells strongly suggest that these drugs possess immunomodulatory properties, which seems to be crucial in the medical practice, especially in the therapy of hypertensive patients with other accompanying inflammatory-based diseases, such as type II diabetes, developed metabolic syndrome, allergies or autoimmunity.

Immunomodulatory Activity of the Most Commonly Used Antihypertensive Drugs-Angiotensin Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers

This review article is focused on antihypertensive drugs, namely angiotensin converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), and their immunomodulatory properties reported in hypertensive patients as well as in experimental settings involving studies on animal models and cell lines. The immune regulatory action of ACEI and ARB is mainly connected with the inhibition of proinflammatory cytokine secretion, diminished expression of adhesion molecules, and normalization of CRP concentration in the blood plasma. The topic has significant importance in future medical practice in the therapy of patients with comorbidities with underlying chronic inflammatory responses. Thus, this additional effect of immune regulatory action of ACEI and ARB may also benefit the treatment of patients with metabolic syndrome, allergies, or autoimmune disorders.

ACE2 and energy metabolism: the connection between COVID-19 and chronic metabolic disorders

The renin-angiotensin system (RAS) has currently attracted increasing attention due to its potential function in regulating energy homeostasis, other than the actions on cellular growth, blood pressure, fluid, and electrolyte balance. The existence of RAS is well established in metabolic organs, including pancreas, liver, skeletal muscle, and adipose tissue, where activation of angiotensin-converting enzyme (ACE) - angiotensin II pathway contributes to the impairment of insulin secretion, glucose transport, fat distribution, and adipokines production. However, the activation of angiotensin-converting enzyme 2 (ACE2) - angiotensin (1-7) pathway, a novel branch of the RAS, plays an opposite role in the ACE pathway, which could reverse these consequences by improving local microcirculation, inflammation, stress state, structure remolding, and insulin signaling pathway. In addition, new studies indicate the protective RAS arm possesses extraordinary ability to enhance brown adipose tissue (BAT) activity and induces browning of white adipose tissue, and consequently, it leads to increased energy expenditure in the form of heat instead of ATP synthesis. Interestingly, ACE2 is the receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is threating public health worldwide. The main complications of SARS-CoV-2 infected death patients include many energy metabolism-related chronic diseases, such as diabetes. The specific mechanism leading to this phenomenon is largely unknown. Here, we summarize the latest pharmacological and genetic tools on regulating ACE/ACE2 balance and highlight the beneficial effects of the ACE2 pathway axis hyperactivity on glycolipid metabolism, as well as the thermogenic modulation.

Renin inhibitors versus angiotensin converting enzyme (ACE) inhibitors for primary hypertension

BACKGROUND

Renin inhibitors (RIs) reduce blood pressure more than placebo, with the magnitude of this effect thought to be similar to that for angiotensin converting enzyme (ACE) inhibitors. However, a drug's efficacy in lowering blood pressure cannot be considered as a definitive indicator of its effectiveness in reducing mortality and morbidity. The effectiveness and safety of RIs compared to ACE inhibitors in treating hypertension is unknown.

OBJECTIVES

To evaluate the benefits and harms of renin inhibitors compared to ACE inhibitors in people with primary hypertension.

SEARCH METHODS

The Cochrane Hypertension Group Information Specialist searched the following databases for randomized controlled trials up to August 2020: the Cochrane Hypertension Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted authors of relevant papers about further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

We included randomized, active-controlled, double-blinded studies (RCTs) with at least four weeks follow-up in people with primary hypertension, which compared renin inhibitors with ACE inhibitors and reported morbidity, mortality, adverse events or blood pressure outcomes. We excluded people with proven secondary hypertension.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected the included trials, evaluated the risks of bias and entered the data for analysis.

MAIN RESULTS

We include 11 RCTs involving 13,627 participants, with a mean baseline age from 51.5 to 74.2 years. Follow-up duration ranged from four weeks to 36.6 months. There was no difference between RIs and ACE inhibitors for the outcomes: all-cause mortality: risk ratio (RR) 1.05, 95% confidence interval (CI) 0.93 to 1.18; 5 RCTs, 5962 participants; low-certainty evidence; total myocardial infarction: RR 0.86, 95% CI 0.22 to 3.39; 2 RCTs, 957 participants; very low-certainty evidence; adverse events: RR 0.98, 95% CI 0.93 to 1.03; 10 RTCs, 6007 participants;  moderate-certainty evidence; serious adverse events: RR 1.21, 95% CI 0.89 to 1.64; 10 RTCs, 6007 participants; low-certainty evidence; and withdrawal due to adverse effects: RR 0.85, 95% CI 0.68 to 1.06; 10 RTCs, 6008 participants; low-certainty evidence. No data were available for total cardiovascular events, heart failure, stroke, end-stage renal disease or change in heart rate. Low-certainty evidence suggested that RIs reduced systolic blood pressure: mean difference (MD) -1.72, 95% CI -2.47 to -0.97; 9 RCTs, 5001 participants;  and diastolic blood pressure: MD -1.18, 95% CI -1.65 to -0.72; 9 RCTs, 5001 participants,  to a greater extent than ACE inhibitors, but we judged this to be more likely due to bias than a true effect.  AUTHORS' CONCLUSIONS: For the treatment of hypertension, we have low certainty that renin inhibitors (RI) and angiotensin converting enzyme (ACE) inhibitors do not differ for all-cause mortality and myocardial infarction. We have low to moderate certainty that they do not differ for adverse events. Small reductions in blood pressure with renin inhibitors compared to ACE inhibitors are of low certainty.  More independent, large, long-term trials are needed to compare RIs with ACE inhibitors, particularly assessing morbidity and mortality outcomes, but also on blood pressure-lowering effect.

The use of aliskiren as an antifibrotic drug in experimental models: A systematic review

Aliskiren is an oral antihypertensive medication that acts by directly inhibiting renin. High levels of circulating renin and prorenin activate the pathological signaling pathway of fibrosis. This drug also reduces oxidative stress. Thus, the aim of this systematic review is to analyze experimental studies that show the actions of aliskiren on fibrosis. PubMed and LILACS databases were consulted using the keywords aliskiren and fibrosis within the period between 2005 and 2017. Fifty-three articles were analyzed. In the heart, aliskiren attenuated remodeling, hypertrophy, inflammatory cytokines, collagen deposition, and oxidative stress. In the kidneys, there was a reduction in interstitial fibrosis, the infiltration of inflammatory cells, apoptosis, proteinuria, and in the recruitment of macrophages. In diabetic models, an improvement in the albumin/creatinine relationship and in the insulin pathway in skeletal muscles was observed; aliskiren was beneficial to pancreatic function and glucose tolerance. In the liver, aliskiren reduced fibrosis, steatosis, inflammatory cytokines, and collagen deposition. In the lung and peritoneal tissues, there was a reduction in fibrosis. Many studies have reported on the beneficial effects of aliskiren on endothelial function and arterial rigidity. A reduction in fibrosis in different organs is cited by many authors, which complies with the results found in this review. However, studies diverge on the use of the drug in diabetic patients. Aliskiren has antifibrotic potential in several experimental models, interfering with the levels of fibrogenic cytokines and oxidative stress. Therefore, its use in diseases in which fibrosis plays an important pathophysiological role is suggested.

Comparison of the Effect of Aliskiren Versus Negative Controls on Aortic Stiffness in Patients With Marfan Syndrome Under Treatment With Atenolol

INTRODUCTION AND OBJECTIVES

The aim of this study was to evaluate the effect of aliskiren on aortic stiffness in patients with Marfan syndrome (MS).

METHODS

Twenty-eight MS patients (mean age ± standard deviation: 32.6 ± 10.6 years) were recruited from November 2009 to October 2014. All patients were receiving atenolol as standard beta-blocker therapy. A prospective randomization process was performed to assign participants to either aliskiren treatment (150-300mg orally per day) or no aliskiren treatment (negative control) in an open-label design. Central aortic distensibility and central pulsed wave velocity (PWV) by magnetic resonance imaging (MRI), peripheral PWV, central aortic blood pressure and augmentation index by peripheral tonometry, and aortic dilatation by echocardiography were examined initially and after 24 weeks. The primary endpoint was central aortic distensibility by MRI.

RESULTS

In analyses of differences between baseline and 24 weeks for the aliskiren treatment group vs the negative control group, central distensibility (overall; P = .26) and central PWV (0.2 ± 0.9 vs 0.03 ± 0.7 [m/s]; P = .79) by MRI were not significantly different. Central systolic aortic blood pressure tended to be lower by 14mmHg in patients in the aliskiren treatment group than in the control group (P = .09). A significant decrease in peripheral PWV (brachial-ankle PWV) in the aliskiren treatment group (-1.6 m/s) compared with the control group (+0.28 m/s) was noted (P = .005).

CONCLUSIONS

Among patients with MS, the addition of aliskiren to beta-blocker treatment did not significantly improve central aortic stiffness during a 24-week period.

Nephronophthisis: should we target cysts or fibrosis?

Ciliopathy nephronophthisis (NPHP), a common cause of end-stage renal disease (ESRD) in children and young adults, is characterized by disintegration of the tubular basement membrane accompanied by irregular thickening and attenuation, interstitial fibrosis and tubular atrophy, and occasionally cortico-medullary cyst formation. Pharmacological approaches that delay the development of ESRD could potentially extend the window of therapeutic opportunity for this group of patients, generating time to find an appropriate donor or even for new treatments to mature. In this review we provide an overview of compounds that have been tested to ameliorate kidney cysts and/or fibrosis. We also revisit paclitaxel as a potential strategy to target fibrosis in NPHP. At low dosage this chemotherapy drug shows promising results in rodent models of renal fibrosis. Possible adverse events and safety of paclitaxel treatment in pediatric patients would need to be investigated, as would the efficacy, optimum dose, and administration schedule for the treatment of renal fibrosis in NPHP patients. Paclitaxel is an approved drug for human use with known pharmacokinetics, which could potentially be used in other ciliopathies through targeting the microtubule skeleton.

Aliskiren attenuates oxidative stress and improves tubular status in non-diabetic patients with chronic kidney disease-Placebo controlled, randomized, cross-over study

PURPOSE

Pharmacological inhibition of the renin-angiotensin-aldosteron system (RAAS) may have a beneficial impact on proteinuria and chronic kidney diseases (CKD) progression. Despite recent progress by means of angiotensin-converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), there is still no optimal therapy which can stop progression of the nephropathy. Recently introduced aliskiren is the first orally bioavailable direct renin inhibitor approved for the treatment of hypertension. The purpose was to evaluate the extent of oxidative stress and tubular injury after the direct renin inhibitor, aliskiren compared with placebo and perindopril in patients with non-diabetic chronic kidney disease (NDCKD).

MATERIAL/METHODS

A randomized, double-blind, cross-over trial was performed in 14 patients receiving 300mg aliskiren, 10mg perindopril and placebo in random order. The end point was a change in the urinary excretion of N-acetyl-β-D-glucosaminidase (NAG) and α1-microglobulin (α1m) and 15-F(2α)-isoprostane.

RESULTS

Aliskiren reduced excretion of 15-F(2α)-isoprostane (p=0.03) and α1m (p=0.01) as compared to placebo. There were no differences between aliskiren and perindopril in this regard. NAG urine excretion did not change after aliskiren and perindopril.

CONCLUSIONS

Aliskiren attenuates oxidative stress and may improve functional status of tubules in patients with NDCKD.

Direct renin inhibition in chronic kidney disease

For approximately 6 years, the only commercially available direct renin inhibitor, aliskiren, which inhibits the renin-angiotensin-aldosterone system at the initial rate limiting step, has been marketed for the treatment of hypertension. Concurrently, much attention has been given to the possibility that renin inhibition could hold potential for improved treatment in patients with chronic kidney disease, with diabetic nephropathy as an obvious group of patients to investigate, as the activity of the renin-angiotensin-aldosterone system is enhanced in these patients and as there is an unmet need for improved treatment and prognosis in these patients. Several short term studies have been performed in diabetic nephropathy, showing a consistent effect on the surrogate endpoint lowering of albuminuria, both as monotherapy and in combination with other blockers of the renin-angiotensin-aldosterone system. In addition, combination treatment also seemed safe and effective in patients with impaired kidney function. These initial findings formed the basis for the design of a large morbidity and mortality trial investigating aliskiren as add-on to standard treatment. The study has just concluded, but was terminated early as a beneficial effect was unlikely and there was an increased frequency of side effects. Also in non-diabetic kidney disease a few intervention studies have been carried out, but there is no ongoing hard outcome study. In this review we provide the current evidence for renin inhibition in chronic kidney disease by reporting the studies published so far as well as a perspective on the future possibilities.

[The cortical collecting duct plays a pivotal role in the kidney's local renin-angiotensin system]

The renin-angiotensin system is one of the most important hormone systems in the body, and the regulations as well as the role in the juxtaglomerular apparatus are well known. The present review focuses on renin secretion in a recently described localization, the cortical collecting duct. The authors display it in parallel of the copying strategy of an adult and a developing kidney. Furthermore, based on different animal studies it highlights the local role of renin released from the collecting duct. In chronic angiotensin II-infused, 2-kidney, 1-clip hypertensive model as well as in diabetic rats the major source of (pro)renin is indeed the collecting duct. In this localization this hormone can reach both the systemic circulation and the interstitial renin-angiotensin system components including the newly described (pro)renin receptor, by which (pro)renin is able to locally activate pro-fibrotic intracellular signal pathways. Consequently, one can postulate that in the future renin may serve either as a new therapeutic target in nephropathy associated with both hypertension and diabetes or as an early diagnostic marker in chronic diseases leading to nephropathy.

Direct renin inhibition--a promising strategy for renal protection?

Activation of the renin–angiotensin–aldosterone system (RAAS) plays a key role in the progression of chronic kidney disease (CKD). RAAS inhibitors, such as angiotensin converting enzyme inhibitors (ACEis) and angiotensin II receptor blockers (ARBs), decrease the rate of progression of diabetic and non-diabetic nephropathies and are first-line therapies for CKD. Although these agents are highly effective, current therapeutic strategies are unable to sufficiently suppress the RAAS and stop CKD progression. Aliskiren, the first in a new class of RAAS-inhibiting agents (direct renin inhibitors) has been approved to treat hypertension. Aliskiren exerts renoprotective, cardioprotective, and anti-atherosclerotic effects in animal models that appear to be independent of its blood pressure lowering activity. Early clinical studies using urinary protein excretion as a marker of renal involvement suggest a possibly novel role for aliskiren in treating CKD. This review discusses the antiproteinuric efficacy and safety of aliskiren and considers the evidence for its potential renoprotection.

The safety and short-term efficacy of aliskiren in the treatment of immunoglobulin a nephropathy--a randomized cross-over study

Background

Laboratory research and previous study suggest that aliskiren, a direct renin inhibitor, has anti-proteinuric effects. We conducted a randomized crossover study to evaluate the anti-proteinuric effect of aliskiren in patients with immunoglobulin A (IgA) nephropathy.

Methods

We studied 22 patients with biopsy-proven IgA nephropathy and persistent proteinuria despite angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB). Patients were randomized to either oral aliskiren 300 mg/day or placebo for 16 weeks and then crossed over to the other treatment arm after a washout period. Proteinuria, estimated glomerular filtration rate (eGFR), blood pressure, and serum potassium were monitored.

Results

After aliskiren treatment, there was a significant reduction in proteinuria in 4 weeks (1.76±0.95 to 1.03±0.69 g:g-Cr, p<0.0001), which remained at a low level throughout the treatment period. There was a significant difference in proteinuria between the aliskiren and placebo groups from 4 to 16 weeks after treatment (p<0.01 for all comparisons). After aliskiren treatment, there were modest but statistically significant reductions in eGFR (57.2±29.1 to 54.8±29.3 ml/min/1.73 m², p = 0.013) and diastolic blood pressure (72.6±12.3 to 66.2±11.2 mmHg, p<0.0001). None of the patient developed severe hyperkalemia (serum potassium ≥6.0 mmol/l) during the study period.

Conclusions

Aliskiren has anti-proteinuric effect in patients with IgA nephropathy and persistent proteinuria despite ACE inhibitor or ARB. Further studies are needed to confirm the renal protecting effect of direct renin inhibition in chronic proteinuric kidney diseases.

Trial Registration

ClinicalTrials.gov NCT00870493

Circulating bone morphogenetic protein-7 and transforming growth factor-β1 are better predictors of renal end points in patients with type 2 diabetes mellitus

Albuminuria and a reduced glomerular filtration rate are conventional predictors of a future decline in kidney function in patients with type 2 diabetes mellitus. Using a nested case-control study we assessed whether circulating transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-7 (BMP-7) levels more accurately predict renal end points than the conventional markers. Cases were defined as those who developed a renal end point (doubling of serum creatinine to at least 200 μmol/l, the need for renal replacement therapy, or death due to renal disease) during the study. Using propensity scoring, two controls were selected for each of 281 cases. Participants who developed renal end points had significantly higher total TGF-β1, lower BMP-7 levels, and a higher total TGF-β1 to BMP-7 ratio at baseline. A graded increase in risk was found in individuals with lower BMP-7 levels (odds ratio 24.07, for the lowest to the highest tertile), or significantly higher TGF-β1 levels (odds ratio for the highest to the lowest tertile, 8.43). The area under the receiver operating characteristic curve (c-statistic) for the conventional predictors was 0.73. Using BMP-7 and total and active TGF-β1, the c-statistic was 0.94 (significantly higher to conventional predictors). Thus, our results suggest these novel kidney markers are better predictors of renal progression than the conventional predictors in patients with type 2 diabetes mellitus.