Renin-guided treatment of hypertension: time for action

Molecular Imaging of Renin Activity using Fluorogenic Nanoprobes for Precision Antihypertensive Therapy

Life-threatening hypertension remains inadequately controlled in clinics due to its heterogeneous renin levels. Rapid stratification of hypertension through renin analysis is crucial for effective personalized treatment, yet an ultrasensitive detection approach is currently lacking. Here, we report activatable renin nanoprobes (ARNs) for non-invasive and ultrasensitive profiling of renin activity and guiding antihypertensive treatment decision through near-infrared fluorescence (NIRF) in vivo imaging and in vitro urinalysis. ARNs are intrinsically non-fluorescent due to NIRF reporter connected to a gold nanocluster through a renin-responsive peptide. In hyperreninemia mouse models, ARNs specifically react with renin to liberate the renal clearable NIRF reporter for accurate renin detection that outperforms the gold standard radioimmunoassay. Such specific and sensitive detection also enables imaging-based high-throughput screening of antihypertensive drugs. In hypertensive rat models, ARNs enable ultrasensitive detection of both plasma and urinary renin, facilitating renin-guided precision treatment and significantly improving hypertension control rate (90 % versus 58 %). Our nanoprobe platform holds great potential for assisting clinicians in rapidly and accurately classifying hypertensive patients and improving outcomes through tailored treatment selection.

Cracking the Code: A Case Report on Low-Renin Hypertension

Low-renin hypertension (LRH) is characterized by hypertension accompanied by low serum renin levels. LRH is a spectrum, including low-renin essential hypertension (LREH), primary hyperaldosteronism, and several acquired or familial secondary forms. Here, we present a case of LRH. A 57-year-old female with resistant hypertension on multiple antihypertensive medications presented for blood pressure management. Workup for secondary causes of hypertension revealed low renin levels with normal aldosterone. The patient was initiated on spironolactone and responded quickly with normal blood pressure on a follow-up visit. LRH is an under-recognized etiology for uncontrolled hypertension. It can be secondary to several different causes. Although treatment of LREH is essentially the same as regular patients, these patients tend to respond well to sodium-volume-depleting diuretics, mineralocorticoid receptor blockers, and epithelial sodium channels (ENaC) blockers.

Effect of diuretics on plasma aldosterone and potassium in primary hypertension: A systematic review and meta-analysis

AIM

By contrast with drugs inhibiting the renin-angiotensin-aldosterone system (RAAS), diuretics stimulate renin release by the kidneys. Although plasma aldosterone (PA) is thought to be mainly regulated by RAAS activity, serum potassium has been shown to be an important factor in animal models and humans. Here we perform a systematic review and meta-analysis of randomised controlled trials (RCT) in hypertension investigating the effects of diuretic therapy on PA and the correlation of change in PA with that of potassium and blood pressure (BP).

METHODS

Three databases were searched: MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL). Titles were first screened by title and abstract for relevance before full-text articles were assessed for eligibility according to a predefined inclusion/exclusion criteria.

RESULTS

A total of 1139 articles were retrieved, of which 42 met the prespecified inclusion/exclusion criteria. The average standardised difference in mean PA was similar for all classes of diuretic: thiazide/thiazide-like 0.299 (95% confidence interval [CI] 0.150, 0.447), loop 0.927 (0.37, 1.49), MRA/potassium-sparing 0.265 (0.173, 0.357) and combination 0.466 (0.137, 0.796), Q = 6.33, P = .097. In subjects untreated with another antihypertensive, there was a significant relationship between change in PA and change in systolic BP but no relationship with the change in potassium.

CONCLUSION

In RCTs of diuretic therapy in hypertension, there is an increase in PA with all classes of diuretic and no significant between-class heterogeneity. Change in PA is not related with potassium but correlates with the change in BP in subjects untreated with another antihypertensive medication.

Feasibility of a Clinical Decision Support Tool to Manage Resistant Hypertension: Team-HTN, a Single-arm Pilot Study

INTRODUCTION

Based on defining criteria, hypertension (HTN) affects 31% to 46% of the adult U.S. population and almost 20% of service members. Resistant HTN (rHTN) consumes significant resources, carries substantial morbidity and mortality risk and costs over $350 billion dollars annually. For multiple reasons, only 48.3% of people with HTN are controlled, e.g., undiagnosed secondary HTN, therapeutic or diagnostic inertia, and patient adherence. Our purpose was to determine the feasibility of a web-based clinical decision support tool (CDST) using a renin-aldosterone system (RAS) classification matrix and drug sequencing algorithm to assist providers with the diagnosis and management of uncontrolled HTN (rHTN). Outcomes were blood pressure (BP) rates of control, provider management time, and end-user satisfaction.

METHODS

This two-phase, prospective, non-randomized, single-arm, six-month pilot study was conducted in primary care clinics at a tertiary military medical center. Patients with uncontrolled HTN and primary care providers were recruited. Phase 1 patients checked their BP twice daily (AM and PM), three times weekly using a standardized arm cuff. Patients with rHTN were enrolled in phase 2. Phase 2 patients were managed virtually by providers using the CDST, the RAS classification matrix, and the drug sequencing algorithm which incorporated age, ethnicity, comorbidities, and renin/aldosterone levels. Medications were adjusted every 10 days until BP was at target, using virtual visits.

RESULTS

In total, 54 patients and 16 providers were consented. One transplant patient was disqualified, 29 met phase 2 criteria for rHTN, and 6 providers completed the study. In phase 1, 45% (n = 24) of patients were identified as having apparent uncontrolled HTN using peak diurnal blood pressure (pdBP) home readings. In phase 2 (n = 29), previously undetected RAS abnormalities were identified in 69% (n = 20) of patients. Blood pressure control rates improved from 0% to 23%, 47%, and 58% at 2, 4, and 6 months, respectively. Provider management time was reduced by 17%. Using home pdBP readings identified masked HTN in almost 20% of patients that would have been missed by a single daily AM or PM home BP measurement. Feasibility and satisfaction trends were favorable.

CONCLUSIONS

Despite significant morbidity, mortality, and existing guidelines, over half of hypertensive patients are uncontrolled. Our results suggest that this CDST used with pdBP monitoring is a feasible option to facilitate improved rates of control in rHTN, aid in overcoming therapeutic/diagnostic inertia, improve identification of secondary HTN, and potentially, access. Further research with this tool in a larger population is recommended.

Plasma renin activity-guided strategy for the management of hypertension

Despite the wide array of antihypertensive agents and the availability of national guidelines regarding treatment for hypertension, the disease remains uncontrolled in nearly 50% of affected patients. Furthermore, the number of patients with resistant hypertension continues to increase. For patients with resistant hypertension, the American Heart Association has advocated for clinical studies to determine appropriate pharmacologic treatment strategies. One proposed strategy involves ambulatory measurement of plasma renin activity (PRA) to guide the selection of antihypertensive therapy. Patients with low PRA would be prescribed natriuretic volume-mediated therapies (e.g., diuretics and calcium channel blockers), whereas those with high PRA would receive antirenin system therapies (e.g., β-blockers, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers). This review focuses on the principles of PRA-guided therapy, its historical development, alternative approaches to classifying patients into categories of response to antihypertensive agents, and recent data supporting the use of plasma renin activity-guided hypertension management.

The plasma renin test reveals the contribution of body sodium-volume content (V) and renin-angiotensin (R) vasoconstriction to long-term blood pressure

Body sodium works together with the plasma renin-angiotensin system to ensure adequate blood flow to the tissues. Body sodium content determines the extracellular fluid (ECF) volume ensuring that, with each heart beat, a sufficient volume of fluid is delivered into the arterial space. At the same time the kidneys monitor ECF volume and blood pressure (BP), so that the juxtaglomerular cells can adjust their net secretion rate of renin to maintain an appropriate plasma renin activity (PRA) level. Plasma renin produces angiotensin II (Ang II) to constrict the arterioles and thereby ensure sufficient BP to deliver an appropriate rate of flow for cardiovascular homeostasis. The low renin, sodium-volume dependent (V) form of essential hypertension occurs whenever body sodium content increases beyond the point where plasma renin-angiotensin vasoconstrictor activity is turned off. In contrast, medium to high renin (R) hypertension occurs when too much renin is secreted relative to the body sodium content. Thus, BP = V × R. This volume-vasoconstriction dual support of long-term hypertension is validated by the fact that all effective long-term antihypertensive drug types are either (i) natriuretic to reduce body salt and volume content (anti-V), or (ii) antirenin to reduce or block the activity of the circulating renin-angiotensin system (anti-R). The PRA test defines the relative participation of the concurrent volume and vasoconstrictor factors. In the hypertensive patient PRA testing can guide initiation, addition or subtraction of anti-V or anti-R antihypertensive drug types to thereby improve BP control and prognosis while reducing drug type usage and cost.

Personalized vascular medicine: individualizing drug therapy

Personalized medicine refers to the application of an individual's biological fingerprint - the comprehensive dataset of unique biological information - to optimize medical care. While the principle itself is straightforward, its implementation remains challenging. Advances in pharmacogenomics as well as functional assays of vascular biology now permit improved characterization of an individual's response to medical therapy for vascular disease. This review describes novel strategies designed to permit tailoring of four major pharmacotherapeutic drug classes within vascular medicine: antiplatelet therapy, antihypertensive therapy, lipid-lowering therapy, and antithrombotic therapy. Translation to routine clinical practice awaits the results of ongoing randomized clinical trials comparing personalized approaches with standard of care management.

Rationale for combining a direct renin inhibitor with other renin- angiotensin system blockers. Focus on aliskiren and combinations

Inhibition of the renin-angiotensin system has been a highly successful therapeutic approach for the prevention of hypertension-related end organ damage. Angiotensin converting enzyme inhibitors and angiotensin II receptor blockers lower blood pressure and reduce morbidity and mortality in patients with cardiovascular and kidney disease. However, progression to end-stage disease remains common in these patient populations. A compensatory increase in plasma renin activity occurs with the use of either angiotensin converting enzyme inhibitors or angiotensin II receptor blockers, thus causing increased levels of angiotensin II, which may limit the therapeutic effectiveness of these agents. The direct renin inhibitor, aliskiren, suppresses the renin-angiotensin system by inhibiting its first and rate-limiting step. This early inhibition reduces the production of all downstream components of the system. In this review, recent clinically relevant advances in the understanding of renin-angiotensin system biology are explored as a rationale for combining aliskiren with other blockers of the renin-angiotensin system. These combinations more fully inhibit the renin-angiotensin system, with the goal of providing additional therapeutic benefits in diseases associated with chronic activation of the renin-angiotensin system.