Hypertension in kidney transplantation is associated with an early renal nerve sprouting

Long-Term Safety and Efficacy of Transcatheter Microwave and Radiofrequency Denervation in a Chronic Ovine Model

BACKGROUND

Transcatheter renal denervation (RDN) has had inconsistent efficacy and concerns for durability of denervation. We aimed to investigate long-term safety and efficacy of transcatheter microwave RDN in vivo in normotensive sheep in comparison to conventional radiofrequency ablation.

METHODS AND RESULTS

Sheep underwent bilateral RDN, receiving 1 to 2 microwave ablations (maximum power of 80-120 W for 240 s-480 s) and 12 to 16 radiofrequency ablations (180 s-240 s) in the main renal artery in a paired fashion, alternating the side of treatment, euthanized at 2 weeks (acute N=15) or 5.5 months (chronic N=15), and compared with undenervated controls (N=4). Microwave RDN produced substantial circumferential perivascular injury compared with radiofrequency at both 2 weeks [area 239.8 (interquartile range [IQR] 152.0-343.4) mm2 versus 50.1 (IQR, 32.0-74.6) mm2, P <0.001; depth 16.4 (IQR, 13.9-18.9) mm versus 7.5 (IQR, 6.0-8.9) mm P <0.001] and 5.5 months [area 20.0 (IQR, 3.4-31.8) mm2 versus 5.0 (IQR, 1.4-7.3) mm2, P=0.025; depth 5.9 (IQR, 1.9-8.8) mm versus 3.1 (IQR, 1.2-4.1) mm, P=0.005] using mixed models. Renal denervation resulted in significant long-term reductions in viability of renal sympathetic nerves [58.9% reduction with microwave (P=0.01) and 45% reduction with radiofrequency (P=0.017)] and median cortical norepinephrine levels [71% reduction with microwave (P <0.001) and 72.9% reduction with radiofrequency (P <0.001)] at 5.5 months compared with undenervated controls.

CONCLUSIONS

Transcatheter microwave RDN produces deep circumferential perivascular ablations without significant arterial injury to provide effective and durable RDN at 5.5 months compared with radiofrequency RDN.

Device's design and clinical perspectives for resistant hypertension therapy

Introduction

Hypertension is the leading cause of death in the cardiovascular system. Indeed, untreated hypertension can affect one's general health, but medicine can help hypertensive people reduce their chance of developing high blood pressure. However, secondary hypertension remains an unresolved illness.

Areas covered

This review will go through the typical and unusual device-based therapies for resistant hypertension that have arisen in recent years. Further to that, the innovations developed in device-based RH treatment will be covered, as well as the research and studies assessing these novel technologies.

Expert opinion

The innovative device-based techniques that target resistant hypertension provide a potential therapy that has been backed by a number of studies and clinical trials, whereas pharmacological non-adherence and increased sympathetic activity are recognized to be the primary causes of resistant hypertension. Nevertheless, some limitations will be critical for the future of these RH systems, with the device's design and larger RCTs playing a significant role in determining whether a position in routine treatment could be warranted.

Renal Denervation in the Treatment of Resistant Hypertension and Difficult-to-Control Hypertension - Consensus Document of the Croatian Hypertension League - Croatian Society of Hypertension, Croatian Cardiac Society, Croatian Endovascular Initiative, Croatian Society for Diabetes and Metabolic Diseases, Croatian Renal Association, and Croatian Society of Family Physicians of the Croatian Medical Association

Renal denervation (RDN) as a method of treating arterial hypertension (AH) was introduced in Croatia in 2012. A multidisciplinary team and a network of hospitals that diagnose and treat patients with severe forms of AH were established, and a very strict diagnostic-treatment algorithm was prepared. At monthly meetings patients with truly resistant hypertension who were candidates for RDN were discussed. According to the 2021 ESH position statement and 2023 ESH guidelines, RDN is considered an alternative and additional, not a competitive method of treating patients with various forms of AH which must be performed by following a structured procedure and the patient's preference should be considered. In view of the changes in the global scientific community, the Croatian Hypertension League brings this consensus document on RDN conducted with radiofrequency-based catheter, the only currently available method in Croatia. In this document, exclusion and inclusion criteria are shown, as well as three groups of patients in whom RDN could be considered. The new diagnostic-treatment algorithm is prepared and follow-up procedure is explained. In Croatia, RDN is reimbursed by the national insurance company, thus pharmacoeconomic analyses is also shown. Criteria required by an individual centre to be approved of RDN are listed, and plans for prospective research on RDN in Croatia, including the Croatian registry for RDN, are discussed.

Controversies in Hypertension IV: Renal Denervation

Renal denervation is not a cure for hypertension. Although more recent sham-controlled trials were positive, a significant minority of patients in each trial were unresponsive. The optimal patient or patients need to be defined. Combined systolic/diastolic hypertension appears more responsive than isolated systolic hypertension. It remains uncertain whether patients with comorbidities associated with higher adrenergic tone should be targeted, including obesity, diabetes, sleep apnea, and chronic kidney disease. No biomarker can adequately predict response. A key to a successful response is the adequacy of denervation, which currently cannot be assessed in real time. It is uncertain what is the optimal denervation methodology: radiofrequency, ultrasound, or ethanol injection. Radiofrequency requires targeting the distal main renal artery plus major branches and accessory arteries. Although denervation appears to be safe, conclusive data on quality of life, improved target organ damage, and reduced cardiovascular events/mortality are required before denervation can be generally recommended.

Uncontrolled hypertension is associated with increased risk of graft failure in kidney transplant recipients: a nationwide population-based study

Backgroud

Hypertension is highly prevalent in patients with kidney transplantation caused by transplantation-related immunologic or non-immunologic risk factors. However, whether a strict definition of hypertension (≥130/80 mmHg) and subdivided blood pressure (BP) groups are associated with an increased risk of graft failure after kidney transplantation using a nationwide large cohort study are still unknown.

Methods

Using Korean National Health Insurance Service data, we included 14,249 patients who underwent kidney transplantation from 2002 to 2016. Patients were categorized into five BP groups according to the 2021 Kidney Disease: Improving Global Outcomes practice guidelines for BP management: normal BP (<120/80 mmHg), elevated BP (120-129/ < 80 mmHg), incident hypertension (≥130/80 mmHg), and controlled or uncontrolled hypertension with anti-hypertensive medications.

Results

The primary outcome was graft failure, which occurred in 1934 (13.6%) participants during the 6-year follow-up. After adjusting for covariates, hypertension was associated with a higher risk of graft failure [Adjusted hazard ratio (AHR), 1.70; 95% confidence interval (CI), 1.48-1.96)] than no-hypertension. The AHR for graft failure was the highest in patients with uncontrolled hypertension (AHR, 2.13; 95% CI, 1.80-2.52). The risk of graft failure had a linear relationship with systolic and diastolic BP, and pulse pressure.

Conclusions

In this nationwide population-based study, hypertension ≥130/80 mmHg based on the 2021 KDIGO BP guidelines in kidney transplantion recipients, and elevated systolic and diastolic BP, and pulse pressure were associated with the risk of developing graft failure in kidney transplant recipients.

Histological evidence supporting the durability of successful radiofrequency renal denervation in a normotensive porcine model

BACKGROUND

Sustained blood pressure reductions after radiofrequency (RF) renal denervation (RDN) have been reported to 3 years in patients with uncontrolled hypertension. However, mechanistic data to support procedural durability are lacking. We aimed to quantify the long-term nerve anatomic and functional effects of RF RDN in a preclinical model.

METHODS

Bilateral RF RDN was performed in 20 normotensive swine. Renal tissue samples were obtained in the RDN-treated groups at 7 ( n  = 6), 28 ( n  = 6), and 180 days ( n  = 8) postprocedure for quantification of cortical norepinephrine (NE) levels and renal cortical axon density. Tissue fibrosis, necrosis and downstream nerve fiber atrophy (axonal loss) were also scored for each sample. Three additional untreated groups ( n  = 6, n  = 6 and n  = 8, respectively) served as control.

RESULTS

Pathologic nerve changes were characterized by necrosis in the ablated region at 7 days that partially resolved by 28 days and fully resolved at 180 days. Axonal loss was apparent within and downstream to the ablation regions and was evident at 7, 28 and 180 days in the main vessel and branch vessels. Consequently, renal cortical axon density and corresponding cortical NE levels were significantly reduced at 7 days in the RDN vs. control group and remained suppressed at 180 days.

CONCLUSIONS

Reductions in renal NE, cortical axon density and downstream axonal loss caused by axonal destruction persisted through 180 days post-RDN in a normotensive swine model. These results suggest functional nerve regrowth after RF RDN is unlikely and support published clinical evidence that the procedure results in durable blood pressure reduction.

Renal Sympathetic Denervation for Hypertension

Arterial hypertension is the most prevalent global modifiable risk factor for cardiovascular morbidity and mortality. Despite the availability of numerous pharmacologic treatments, many patients do not achieve guideline-recommended blood pressure targets. Therefore, renal sympathetic denervation (RDN), a process in which catheter-directed techniques are used to ablate portions of the renal artery to reduce sympathetic activity, has been extensively investigated as a complementary and nonpharmacologic approach for the treatment of arterial hypertension. This review seeks to discuss the pathophysiological rationale of this strategy, to survey its history and development, and to highlight the current clinical evidence and possible future directions of its employment. In sum, RDN has demonstrated itself to be a safe and well-tolerated endovascular intervention that can reliably contribute to improved blood pressure control and, perhaps ultimately, significant cardiovascular prognosis.

Nerve regeneration in transplanted organs and tracer imaging studies: A review

The technique of organ transplantation is well established and after transplantation the patient might be faced with the problem of nerve regeneration of the transplanted organ. Transplanted organs are innervated by the sympathetic, parasympathetic, and visceral sensory plexuses, but there is a lack of clarity regarding the neural influences on the heart, liver and kidneys and the mechanisms of their innervation. Although there has been considerable recent work exploring the potential mechanisms of nerve regeneration in organ transplantation, there remains much that is unknown about the heterogeneity and individual variability in the reinnervation of organ transplantation. The widespread availability of radioactive nerve tracers has also made a significant contribution to organ transplantation and has helped to investigate nerve recovery after transplantation, as well as providing a direction for future organ transplantation research. In this review we focused on neural tracer imaging techniques in humans and provide some conceptual insights into theories that can effectively support our choice of radionuclide tracers. This also facilitates the development of nuclear medicine techniques and promotes the development of modern medical technologies and computer tools. We described the knowledge of neural regeneration after heart transplantation, liver transplantation and kidney transplantation and apply them to various imaging techniques to quantify the uptake of radionuclide tracers to assess the prognosis of organ transplantation. We noted that the aim of this review is both to provide clinicians and nuclear medicine researchers with theories and insights into nerve regeneration in organ transplantation and to advance imaging techniques and radiotracers as a major step forward in clinical research. Moreover, we aimed to further promote the clinical and research applications of imaging techniques and provide clinicians and research technology developers with the theory and knowledge of the nerve.

Efficacy and safety of Sodium-Glucose-Transporter-2 inhibitors in kidney transplant patients

PURPOSE OF REVIEW

This review discusses current evidence and future perspectives for use of SLT2 inhibitors in kidney transplant recipients (KTRs).

RECENT FINDINGS

Sodium-Glucose-Transporter-2 inhibitors (SGLT2is) lower plasma glucose in patients with type 2 diabetes, and protect against heart failure and progression of chronic kidney disease by a glucose-independent mechanism. Most of the current studies with SGLT2is in kidney transplant patients are however short-term retrospective case studies. These, together with one small randomized clinical trial, show that SGLT2is lower glucose also in KTRs with type 2 diabetes or posttransplant diabetes mellitus. Larger reductions in HbA1c (-0.5 to 1.5% points) are seen only in patients with estimated GFR > 60 ml/min/1.73m2 and HbA1c > 8%. With lower gomerular filtration rate (GFR) or glycated hemoglobin (HbA1c) the glucose-lowering effect is trivial. However, a reduction in body weight, blood pressure and uric acid is also seen, whereas the frequency of side effects (mycotic or urinary tract infections) does not seem to exceed what is seen in nontransplanted patients. Long-term effects on GFR have not been studied in kidney transplanted patients, but SGLT2is induce an early dip in GFR also in these patients. This could signal a beneficial long-term effect on renal hemodynamics.

SUMMARY

SGLT2is lower glucose safely also in patients with single kidney grafts, but long-term kidney function and patient survival are yet to be explored.

The influence of inhibiting renal neural regeneration on the efficacy of renal denervation to chronic heart failure

Aims

Some studies support the occurrence of nerve regeneration in renal arteries after renal denervation (RDN). But it is unclear whether inhibiting reinnervation after RDN is beneficial to enhancing the effect of RDN on chronic heart failure (CHF).

Methods and results

Chronic heart failure Sprague Dawley rats induced by transverse aortic constriction were administered with the analogue of Nogo‐B (Nogo group) or its antagonist (NEP group) respectively after RDN. Echocardiography, messenger RNA, and protein expression of calcitonin gene‐related peptide (CGRP) in renal artery and nerves surrounding renal artery were detected. Relative protein expression of CGRP was significantly decreased in the Nog group compared with the RDN group (0.64 ± 0.51 vs. 1.68 ± 1.07, P = 0.048). The number of nerves surrounding renal artery was higher in the NEP group than in the Nog group. Left ventricular end‐systolic volume and diameter (LVVs and LVDs) were greatly decreased, and left ventricular ejection fraction (LVEF) and fractional shortening (FS) increased significantly in the RDN, Nog and NEP groups when compared with the HF group (all P < 0.05). No significant differences were observed in left ventricular end‐diastolic volume and diameter; LVDs; LVVs; FS; LVEF; and the levels of plasma renin, noradrenaline, and N‐terminal pro‐B‐type natriuretic peptide among three groups: the RDN, Nog, and NEP groups.

Conclusions

Reinnervation of renal artery occurred in CHF rats after RDN, which had no effect on therapeutic role of RDN in CHF, and inhibiting this neural regeneration had no clinical significance and did not affect the efficacy of RDN to CHF.

Renal Denervation by Noninvasive Stereotactic Radiotherapy Induces Persistent Reduction of Sympathetic Activity in a Hypertensive Swine Model

Background

We have previously reported the feasibility of noninvasive stereotactic body radiotherapy (SBRT) as a novel approach for renal denervation.

Methods and Results

Herein, from a translational point of view, we assessed the antihypertensive effect and chronological evolution of SBRT‐induced renal nerve injury within 6 months in a hypertensive swine model. Hypertension was induced in swine by subcutaneous implantation of deoxycorticosterone acetate pellets in combination with a high‐salt diet. A single dose of 25 Gy with SBRT was delivered for renal denervation in 9 swine within 3.4±1.0 minutes. Blood pressure levels at baseline and 1 and 6 months post‐SBRT were comparable to control (n=5), whereas renal norepinephrine was significantly lower at 6 months (P<0.05). Abdominal computed tomography, performed before euthanasia and renal function assessment, remained normal. Standard semiquantitative histological assessment showed that compared with control (1.4±0.4), renal nerve injury was greater at 1 month post‐SBRT (2.3±0.3) and peaked at 6 months post‐SBRT (3.2±0.8) (P<0.05), along with a higher proportion of active caspase‐3–positive nerves (P<0.05). Moreover, SBRT resulted in continuous dysfunction of renal sympathetic nerves and low level of nerve regeneration in 6 months by immunohistochemistry analysis.

Conclusions

SBRT delivering 25 Gy for renal denervation was safe and related to sustained reduction of sympathetic activity by aggravating nerve damage and inhibiting nerve regeneration up to 6 months; however, its translation to clinical trial should be cautious because of the negative blood pressure response in the deoxycorticosterone acetate–salt hypertensive swine model.

Renal denervation does not affect hypertension or the renin-angiotensin system in a rodent model of juvenile-onset polycystic kidney disease: clinical implications

We examined the effect of total and afferent renal denervation (RDN) on hypertension and the renin-angiotensin system (RAS) in a rodent model of juvenile-onset polycystic kidney disease (PKD). Lewis Polycystic Kidney (LPK) and control rats received total, afferent or sham RDN by periaxonal application of phenol, capsaicin or normal saline, respectively, and were monitored for 4-weeks. Afferent RDN did not affect systolic blood pressure (SBP) determined by radiotelemetry in either strain (n = 19) while total RDN significantly reduced SBP in Lewis rats 4-weeks post-denervation (total vs. sham, 122 ± 1 vs. 130 ± 2 mmHg, P = 0.002, n = 25). Plasma and kidney renin content determined by radioimmunoassay were significantly lower in LPK vs. Lewis (plasma: 278.2 ± 6.7 vs. 376.5 ± 11.9 ng Ang I/ml/h; kidney: 260.1 ± 6.3 vs. 753.2 ± 37.9 ng Ang I/mg/h, P < 0.001, n = 26). These parameters were not affected by RDN. Intrarenal mRNA expression levels of renin, angiotensinogen, angiotensin-converting enzyme (ACE)2, and angiotensin II receptor type 1a were significantly lower, whereas ACE1 expression was significantly higher in the LPK vs. Lewis (all P < 0.05, n = 26). This pattern of intrarenal RAS expression was not changed by RDN. In conclusion, RDN does not affect hypertension or the RAS in the LPK model and indicates RDN might not be a suitable antihypertensive strategy for individuals with juvenile-onset PKD.

Sympathetic innervation of the mouse kidney and liver arising from prevertebral ganglia

The sympathetic nervous system (SNS) plays a crucial role in the regulation of renal and hepatic functions. Although sympathetic nerves to the kidney and liver have been identified in many species, specific details are lacking in the mouse. In the absence of detailed information of sympathetic prevertebral innervation of specific organs, selective manipulation of a specific function will remain challenging. Despite providing major postganglionic inputs to abdominal organs, limited data are available about the mouse celiac-superior mesenteric complex. We used tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DbH) reporter mice to visualize abdominal prevertebral ganglia. We found that both the TH and DbH reporter mice are useful models for identification of ganglia and nerve bundles. We further tested if the celiac-superior mesenteric complex provides differential inputs to the mouse kidney and liver. The retrograde viral tracer, pseudorabies virus (PRV)-152 was injected into the cortex of the left kidney or the main lobe of the liver to identify kidney-projecting and liver-projecting neurons in the celiac-superior mesenteric complex. iDISCO immunostaining and tissue clearing were used to visualize unprecedented anatomical detail of kidney-related and liver-related postganglionic neurons in the celiac-superior mesenteric complex and aorticorenal and suprarenal ganglia compared with TH-positive neurons. Kidney-projecting neurons were restricted to the suprarenal and aorticorenal ganglia, whereas only sparse labeling was observed in the celiac-superior mesenteric complex. In contrast, liver-projecting postganglionic neurons were observed in the celiac-superior mesenteric complex and aorticorenal and suprarenal ganglia, suggesting spatial separation between the sympathetic innervation of the mouse kidney and liver.

Hypertension in kidney transplantation: a consensus statement of the 'hypertension and the kidney' working group of the European Society of Hypertension

Hypertension is common in kidney transplantation recipients and may be difficult to treat. Factors present before kidney transplantation, related to the transplantation procedure itself and factors developing after transplantation may contribute to blood pressure (BP) elevation in kidney transplant recipients. The present consensus is based on the results of three recent systematic reviews, the latest guidelines and the current literature. The current transplant guidelines, which recommend only office BP assessments for risk stratification in kidney transplant patients should be reconsidered, given the presence of white-coat hypertension and masked hypertension in this population and the better prediction of adverse outcomes by 24-h ambulatory BP monitoring as indicated in recent systematic reviews. Hypertension is associated with adverse kidney and cardiovascular outcomes and decreased survival in kidney transplant recipients. Current evidence suggests calcium channel blockers could be the preferred first-step antihypertensive agents in kidney transplant patients, as they improve graft function and reduce graft loss, whereas no clear benefit is documented for renin-angiotensin system inhibitor use over conventional treatment in the current literature. Randomized control trials demonstrating the clinical benefits of BP lowering on kidney and major cardiovascular events and recording patient-related outcomes are still needed. These trials should define optimal BP targets for kidney transplant recipients. In the absence of kidney transplant-specific evidence, BP targets in kidney transplant recipients should be similar to those in the wider chronic kidney disease population.

Microalbuminuria After Kidney Transplantation Predicts Cardiovascular Morbidity

Background: Microalbuminuria is a well-characterized marker of kidney malfunction, both in diabetic and non-diabetic populations, and is used as a prognostic marker for cardiovascular morbidity and mortality. A few studies implied that it has the same value in kidney transplanted patients, but the information relies on spot or dipstick urine protein evaluations, rather than the gold standard of timed urine collection.

Methods: We revisited a cohort of 286 kidney transplanted patients, several years after completing a meticulously timed urine collection and assessed the prevalence of major cardiovascular adverse events (MACE) in relation to albuminuria.

Results: During a median follow up of 8.3 years (IQR 6.4–9.1) 144 outcome events occurred in 101 patients. By Kaplan-Meier analysis microalbuminuria was associated with increased rate of CV outcome or death (p = 0.03), and this was still significant after stratification according to propensity score quartiles (p = 0.048). Time dependent Cox proportional hazard analysis showed independent association between microalbuminuria and CV outcomes 2 years following microalbuminuria detection (HR 1.83, 95% CI 1.07–2.96).

Conclusions: Two years after documenting microalbuminuria in kidney transplanted patients, their CVD risk was increased. There is need for primary prevention strategies in this population and future studies should address the topic.

Approach and Management of Hypertension After Kidney Transplantation

Hypertension is one of the most common cardiovascular co-morbidities after successful kidney transplantation. It commonly occurs in patients with other metabolic diseases, such as diabetes mellitus, hyperlipidemia, and obesity. The pathogenesis of post-transplant hypertension is complex and is a result of the interplay between immunological and non-immunological factors. Post-transplant hypertension can be divided into immediate, early, and late post-transplant periods. This classification can help clinicians determine the etiology and provide the appropriate management for these complex patients. Volume overload from intravenous fluid administration is common during the immediate post-transplant period and commonly contributes to hypertension seen early after transplantation. Immunosuppressive medications and donor kidneys are associated with post-transplant hypertension occurring at any time point after transplantation. Transplant renal artery stenosis (TRAS) and obstructive sleep apnea (OSA) are recognized but common and treatable causes of resistant hypertension post-transplantation. During late post-transplant period, chronic renal allograft dysfunction becomes an additional cause of hypertension. As these patients develop more substantial chronic kidney disease affecting their allografts, fibroblast growth factor 23 (FGF23) increases and is associated with increased cardiovascular and all-cause mortality in kidney transplant recipients. The exact relationship between increased FGF23 and post-transplant hypertension remains poorly understood. Blood pressure (BP) targets and management involve both non-pharmacologic and pharmacologic treatment and should be individualized. Until strong evidence in the kidney transplant population exists, a BP of <130/80 mmHg is a reasonable target. Similar to complete renal denervation in non-transplant patients, bilateral native nephrectomy is another treatment option for resistant post-transplant hypertension. Native renal denervation offers promising outcomes for controlling resistant hypertension with no significant procedure-related complications. This review addresses the epidemiology, pathogenesis, and specific etiologies of post-transplant hypertension including TRAS, calcineurin inhibitor effects, OSA, and failed native kidney. The cardiovascular and survival outcomes related to post-transplant hypertension and the utility of 24-h blood pressure monitoring will be briefly discussed. Antihypertensive medications and their mechanism of actions relevant to kidney transplantation will be highlighted. A summary of guidelines from different professional societies for BP targets and antihypertensive medications as well as non-pharmacological interventions, including bilateral native nephrectomy and native renal denervation, will be reviewed.

Device-Based Neuromodulation for Resistant Hypertension Therapy

Despite availability of effective drugs for hypertension therapy, significant numbers of hypertensive patients fail to achieve recommended blood pressure levels on ≥3 antihypertensive drugs of different classes. These individuals have a high prevalence of adverse cardiovascular events and are defined as having resistant hypertension (RHT) although nonadherence to prescribed antihypertensive medications is common in patients with apparent RHT. Furthermore, apparent and true RHT often display increased sympathetic activity. Based on these findings, technology was developed to treat RHT by suppressing sympathetic activity with electrical stimulation of the carotid baroreflex and catheter-based renal denervation (RDN). Over the last 15 years, experimental and clinical studies have provided better understanding of the physiological mechanisms that account for blood pressure lowering with baroreflex activation and RDN and, in so doing, have provided insight into which patients in this heterogeneous hypertensive population are most likely to respond favorably to these device-based therapies. Experimental studies have also played a role in modifying device technology after early clinical trials failed to meet key endpoints for safety and efficacy. At the same time, these studies have exposed potential differences between baroreflex activation and RDN and common challenges that will likely impact antihypertensive treatment and clinical outcomes in patients with RHT. In this review, we emphasize physiological studies that provide mechanistic insights into blood pressure lowering with baroreflex activation and RDN in the context of progression of clinical studies, which are now at a critical point in determining their fate in RHT management.

Morphological evaluation of sympathetic renal innervation in patients with autosomal dominant polycystic kidney disease

Several evidences support the hypothesis that patients affected by autosomal dominant polycystic kidney disease (ASPKD) show a sympathetic renal hyperactivity. Nevertheless, no morphological evidences are available yet. Therefore, the aim of the study was to demonstrate that an increase in sympathetic renal artery innervation was present in the ADPKD patients by using histological methods. In addition, here we correlated the sympathetic renal artery innervation with the evolutionary state of ADPKD (increase in volume of kidney, onset of chronic renal failure and hypertension). To this end, peri-adventitial innervation of renal arteries was studied using morphological methods from 49 patients in total: 29 underwent surgical nephrectomies for ADPKD and 20 non-dialysis patients (CTRL group) undergoing nephrectomy for other diseases. Nerve density (number of nerves per mm²) was evaluated in the peri-adventitial tissue in a concentric ring that was located within 2 mm from the beginning of the adventitia by using immunohistochemistry. The total nerve density was significantly increased in the ADPKD group (1.26 ± 0.82 × mm²) as compared to controls (0.78 ± 0.40 × mm²) (p = 0.02). Hypertensive patients with ADPKD showed a greater nerve density than control hypertensives. However, the increase in renal sympathetic innervation in the ADPKD patients was found to be independent of hypertension, resistance to antihypertensive therapy, age, sex and kidney volume, as demonstrated by the uni and multivariate analysis. In conclusion, our study better clarifies the effect of sympathetic hyperactivity in the progression of polycystic disease.