The Effect of Renal Denervation on T Cells in Patients with Resistant Hypertension.

(1) Background: Sympathetic overactivity is a major contributor to resistant hypertension (RH). According to animal studies, sympathetic overactivity increases immune responses, thereby aggravating hypertension and cardiovascular outcomes. Renal denervation (RDN) reduces sympathetic nerve activity in RH. Here, we investigate the effect of RDN on T-cell signatures in RH. (2) Methods: Systemic inflammation and T-cell subsets were analyzed in 17 healthy individuals and 30 patients with RH at baseline and 6 months after RDN. (3) Results: The patients with RH demonstrated higher levels of pro-inflammatory cytokines and higher frequencies of CD4+ effector memory (TEM), CD4+ effector memory residential (TEMRA) and CD8+ central memory (TCM) cells than the controls. After RDN, systolic automated office blood pressure (BP) decreased by -17.6 ± 18.9 mmHg. Greater BP reductions were associated with higher CD4+ TEM (r -0.421, p = 0.02) and CD8+ TCM (r -0.424, p = 0.02) frequencies at baseline. The RDN responders, that is, the patients with ≥10mmHg systolic BP reduction, showed reduced pro-inflammatory cytokine levels, whereas the non-responders had unchanged inflammatory activity and higher CD8+ TEMRA frequencies with increased cellular cytokine production. (4) Conclusions: The pro-inflammatory state of patients with RH is characterized by altered T-cell signatures, especially in non-responders. A detailed analysis of T cells might be useful in selecting patients for RDN.

α2A-Adrenoceptors Modulate Renal Sympathetic Neurotransmission and Protect against Hypertensive Kidney Disease.

BACKGROUND: Increased nerve activity causes hypertension and kidney disease. Recent studies suggest that renal denervation reduces BP in patients with hypertension. Renal NE release is regulated by prejunctional α2A-adrenoceptors on sympathetic nerves, and α2A-adrenoceptors act as autoreceptors by binding endogenous NE to inhibit its own release. However, the role of α2A-adrenoceptors in the pathogenesis of hypertensive kidney disease is unknown. METHODS: We investigated effects of α2A-adrenoceptor-regulated renal NE release on the development of angiotensin II-dependent hypertension and kidney disease. In uninephrectomized wild-type and α2A-adrenoceptor-knockout mice, we induced hypertensive kidney disease by infusing AngII for 28 days. RESULTS: Urinary NE excretion and BP did not differ between normotensive α2A-adrenoceptor-knockout mice and wild-type mice at baseline. However, NE excretion increased during AngII treatment, with the knockout mice displaying NE levels that were significantly higher than those of wild-type mice. Accordingly, the α2A-adrenoceptor-knockout mice exhibited a systolic BP increase, which was about 40 mm Hg higher than that found in wild-type mice, and more extensive kidney damage. In isolated kidneys, AngII-enhanced renal nerve stimulation induced NE release and pressor responses to a greater extent in kidneys from α2A-adrenoceptor-knockout mice. Activation of specific sodium transporters accompanied the exaggerated hypertensive BP response in α2A-adrenoceptor-deficient kidneys. These effects depend on renal nerves, as demonstrated by reduced severity of AngII-mediated hypertension and improved kidney function observed in α2A-adrenoceptor-knockout mice after renal denervation. CONCLUSIONS: Our findings reveal a protective role of prejunctional inhibitory α2A-adrenoceptors in pathophysiologic conditions with an activated renin-angiotensin system, such as hypertensive kidney disease, and support the concept of sympatholytic therapy as a treatment.

Phosphodiesterase 5 inhibition ameliorates angiotensin II-dependent hypertension and renal vascular dysfunction.

Changes in renal hemodynamics have a major impact on blood pressure (BP). Angiotensin (Ang) II has been shown to induce vascular dysfunction by interacting with phosphodiesterase (PDE)1 and PDE5. The predominant PDE isoform responsible for renal vascular dysfunction in hypertension is unknown. Here, we measured the effects of PDE5 (sildenafil) or PDE1 (vinpocetine) inhibition on renal blood flow (RBF), BP, and renal vascular function in normotensive and hypertensive mice. During acute short-term Ang II infusion, sildenafil decreased BP and increased RBF in C57BL/6 (WT) mice. In contrast, vinpocetine showed no effect on RBF and BP. Additionally, renal cGMP levels were significantly increased after acute sildenafil but not after vinpocetine infusion, indicating a predominant role of PDE5 in renal vasculature. Furthermore, chronic Ang II infusion (500 ng·kg-1·min-1) increased BP and led to impaired NO-dependent vasodilation in kidneys of WT mice. Additional treatment with sildenafil (100 mg·kg-1·day-1) attenuated Ang II-dependent hypertension and improved NO-mediated vasodilation. During chronic Ang II infusion, urinary nitrite excretion, a marker for renal NO generation, was increased in WT mice, whereas renal cGMP generation was decreased and restored after sildenafil treatment, suggesting a preserved cGMP signaling after PDE5 inhibition. To investigate the dependency of PDE5 effects on NO/cGMP signaling, we next analyzed eNOS-KO mice, a mouse model characterized by low vascular NO/cGMP levels. In eNOS-KO mice, chronic Ang II infusion increased BP but did not impair NO-mediated vasodilation. Moreover, sildenafil did not influence BP or vascular function in eNOS-KO mice. These results highlight PDE5 as a key regulator of renal hemodynamics in hypertension.

Angiotensin II-Induced Hypertension Is Attenuated by Reduction of Sympathetic Output in NO-Sensitive Guanylyl Cyclase 1 Knockout Mice.

In the regulation of vascular tone, the dilatory nitric oxide (NO)/cGMP pathway balances vasoconstriction induced by the renin-angiotensin and sympathetic nervous systems. NO-induced cGMP formation is catalyzed by two guanylyl cyclases (GC), NO-sensitive guanylyl cyclase 1 (NO-GC1) and NO-GC2, with indistinguishable enzymatic properties. In vascular smooth muscle cells, NO-GC1 is the major isoform and is responsible for more than 90% of cGMP formation. Despite reduced vasorelaxation, NO-GC1-deficient mice are not hypertensive. Here, the role of NO-GC1 in hypertension provoked by contractile agonists angiotensin II (Ang II) and norepinephrine (NE) was evaluated in NO-GC1-deficient mice. Hypertension induced by chronic Ang II treatment did not differ between wild-type (WT) and NO-GC1 knockout mice (KO). Also, attenuation of NO-dependent aortic relaxation induced by the Ang II treatment was similar in both genotypes and was most probably attributable to an increase of phosphodiesterase 1 expression. Analysis of plasma NE content-known to be influenced by Ang II-revealed lower NE in the NO-GC1 KO under Ang II-treated- and nontreated conditions. The finding indicates reduced sympathetic output and is underlined by the lower heart rate in the NO-GC1 KO. To find out whether the lack of higher blood pressure in the NO-GC1 KO is a result of reduced sympathetic activity counterbalancing the reduced vascular relaxation, mice were challenged with chronic NE application. As the resulting blood pressure was higher in the NO-GC1 KO than in WT, we conclude that the reduced sympathetic activity in the NO-GC1 KO prevents hypertension and postulate a possible sympatho-excitatory action of NO-GC1 counteracting NO-GC1's dilatory effect in the vasculature.

Azilsartan compared to ACE inhibitors in anti-hypertensive therapy: one-year outcomes of the observational EARLY registry.

BACKGROUND: Azilsartan medoxomil (AZL-M), has been demonstrated to be more effective than the other sartans currently in use; however, there is insufficient information available comparing it with ACE-inhibitors. Therefore, we aimed to compare the efficacy, safety, and tolerability of AZL-M with that of ACE-inhibitors in a real life clinical setting. METHODS: The EARLY registry is a prospective, observational, national, multicentre registry with a follow-up period of 12 months. There were two principal objectives: 1) documentation of the achievement of target BP values set according to recent national and international guidelines, and 2) description of the safety profile of AZL-M. RESULTS: A total of 3 849 patients with essential arterial hypertension were recruited from primary care offices in Germany. Patients who initiated monotherapy at baseline comprising either AZL-M or an ACE-inhibitor were included at a ratio of seven to three. Results demonstrated that a blood pressure target of <140/90 mmHg was achieved by a significantly greater proportion of patients in the AZL-M group (61.1 %) compared with the ACE-inhibitor group (56.4 %; p < 0.05; OR, 1.21; 95 % CI, 1.03-1.42), with this finding maintained after adjusting for differences in baseline characteristics. AZL-M appeared to have an equivalent safety profile to the ACE-inhibitors, with a similar incidence of adverse events in the two patient groups (p = 0.73). CONCLUSIONS: These data add to the results of previous randomized controlled clinical trials suggesting that, compared with other agents that target the renin-angiotensin system, AZL-M provides statistically significant albeit small improvements in blood pressure control.

Delayed seroconversion and rapid onset of lymphoproliferative disease after transmission of human T-cell lymphotropic virus type 1 from a multiorgan donor.

BACKGROUND: Human T-cell lymphotropic virus type 1 (HTLV-1) screening of blood and organ donors is not mandatory in Germany because of its low prevalence (about 7/100 000). An HTLV-1 transmission event caused by a multiple organ donor was investigated. Validity of diagnostic procedures and HTLV-1 disease association in immunosuppressed organ recipients were analyzed. METHODS: Two screening immunoassays and an immunoblot (confirmatory assay) were used for detection of HLTV-1/2 antibodies. Proviral DNA was quantified in blood and biopsies of organ recipients by HTLV-1 real-time polymerase chain reaction (PCR). RESULTS: Proviral HTLV-1-DNA was detected in all blood samples of 3 organ recipients (1-100 copies/10(2) cells), but seroconversion was delayed for up to 2 years in screening assays and >6 years in the confirmatory assay. In 2 of 3 organ recipients, a cutaneous T-cell lymphoma was diagnosed 2 and 3 years after infection, respectively. Proviral HTLV-1 DNA concentration was almost 100 copies/10(2) cells in cutaneous lymphoma biopsies whereas in biopsies of other tissues ≤3.0 copies/10(2) cells were found. The third organ recipient did not suffer from lymphoma, but detailed clinical data on this patient were not available to us. CONCLUSIONS: Biopsy results support an etiological role for HTLV-1 in these cases of primary cutaneous T-cell lymphoma after solid organ transplant. HTLV-1-associated lymphoma can arise quickly in immunocompromised transplant recipients. The diagnosis of potentially HTLV-1-associated disease in organ recipients may require PCR because of delayed seroconversion.

Thymosin ß4 and its degradation product, Ac-SDKP, are novel reparative factors in renal fibrosis.

Previously, we found thymosin ß4 (Tß4) is upregulated in glomerulosclerosis and required for angiotensin II-induced expression of plasminogen activator inhibitor-1 (PAI-1) in glomerular endothelial cells. Tß4 has beneficial effects in dermal and corneal wound healing and heart disease, yet its effects in kidney disease are unknown. Here we studied renal fibrosis in wild-type and PAI-1 knockout mice following unilateral ureteral obstruction to explore the impact of Tß4 and its prolyl oligopeptidase tetrapeptide degradation product, N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), in renal fibrosis. Additionally, we explored interactions of Tß4 with PAI-1. Treatment with Ac-SDKP significantly decreased fibrosis in both wild-type and PAI-1 knockout mice, as observed by decreased collagen and fibronectin deposition, fewer myofibroblasts and macrophages, and suppressed profibrotic factors. In contrast, Tß4 plus a prolyl oligopeptidase inhibitor significantly increased fibrosis in wild-type mice. Tß4 alone also promoted repair and reduced late fibrosis in wild-type mice. Importantly, both profibrotic effects of Tß4 plus the prolyl oligopeptidase inhibitor, and late reparative effects of Tß4 alone, were absent in PAI-1 knockout mice. Thus, Tß4 combined with prolyl oligopeptidase inhibition is consistently profibrotic, but by itself has antifibrotic effects in late-stage fibrosis, while Ac-SDKP has consistent antifibrotic effects in both early and late stages of kidney injury. These effects of Tß4 are dependent on PAI-1.

EARLY Treatment with azilsartan compared to ACE-inhibitors in anti-hypertensive therapy--rationale and design of the EARLY hypertension registry.

BACKGROUND: Arterial hypertension is highly prevalent but poorly controlled. Blood pressure (BP) reduction substantially reduces cardiovascular morbidity and mortality. Recent randomized, double-blind clinical trials demonstrated that azilsartan medoxomil (AZM) is more effective in reducing BP than the ubiquitary ACE inhibitor ramipril. Therefore, we aimed to test whether these can be verified under clinical practice conditions. METHODS/DESIGN: The "Treatment with Azilsartan Compared to ACE-Inhibitors in Anti-Hypertensive Therapy" (EARLY) registry is a prospective, observational, national, multicenter registry with a follow-up of up to 12 months. It will include up to 5000 patients on AZM or ACE-inhibitor monotherapy in a ratio of 7 to 3. A subgroup of patients will undergo 24-hour BP monitoring. EARLY has two co-primary objectives: 1) Description of the safety profile of azilsartan and 2) achievement of BP targets based on recent national and international guidelines for patients treated with azilsartan in comparison to those treated with ACE-inhibitors. The most important secondary endpoints are the determination of persistence with treatment and the documentation of cardiovascular and renal events. Recruitment commenced in January 2012 and will be completed by February 2013. CONCLUSIONS: The data obtained will supplement previous results from randomized controlled trials to document the potential value of utilizing azilsartan medoxomil in comparison to ACE-inhibitor treatment for target BP achievement in clinical practice.

Impact of first-line use of caplacizumab on treatment outcomes in immune thrombotic thrombocytopenic purpura.

BACKGROUND: The von Willebrand factor-directed nanobody caplacizumab has greatly changed the treatment of immune thrombotic thrombocytopenic purpura (iTTP) in recent years. Data from randomized controlled trials established efficacy and safety. OBJECTIVES: This study aims to address open questions regarding patient selection, tailoring of therapy duration, obstacles in prescribing caplacizumab in iTTP, effect on adjunct treatment, and outcomes in the real-world setting. METHODS: We report retrospective, observational cohorts of 113 iTTP episodes treated with caplacizumab and 119 historical control episodes treated without caplacizumab. We aggregated data from the caplacizumab phase II/III trials and real-world data from France, the United Kingdom, Germany, and Austria (846 episodes, 396 treated with caplacizumab, and 450 historical controls). RESULTS: Caplacizumab was efficacious in iTTP, independent of the timing of therapy initiation, but curtailed the time of active iTTP only when used in the first-line therapy within 72 hours after diagnosis and until at least partial ADAMTS13-activity remission. Aggregated data from multiple study populations showed that caplacizumab use resulted in significant absolute risk reduction of 2.87% for iTTP-related mortality (number needed to treat 35) and a relative risk reduction of 59%. CONCLUSION: Caplacizumab should be used in first line and until ADAMTS13-remission, lowers iTTP-related mortality and refractoriness, and decreases the number of daily plasma exchange and hospital stay. This trial is registered at www. CLINICALTRIALS: gov as #NCT04985318.

PKC alpha mediates beta-arrestin2-dependent nephrin endocytosis in hyperglycemia.

Nephrin, the key molecule of the glomerular slit diaphragm, is expressed on the surface of podocytes and is critical in preventing albuminuria. In diabetes, hyperglycemia leads to the loss of surface expression of nephrin and causes albuminuria. Here, we report a mechanism that can explain this phenomenon: hyperglycemia directly enhances the rate of nephrin endocytosis via regulation of the ß-arrestin2-nephrin interaction by PKCα. We identified PKCα and protein interacting with c kinase-1 (PICK1) as nephrin-binding proteins. Hyperglycemia induced up-regulation of PKCα and led to the formation of a complex of nephrin, PKCα, PICK1, and ß-arrestin2 in vitro and in vivo. Binding of ß-arrestin2 to the nephrin intracellular domain depended on phosphorylation of nephrin threonine residues 1120 and 1125 by PKCα. Further, cellular knockdown of PKCα and/or PICK1 attenuated the nephrin-ß-arrestin2 interaction and abrogated the amplifying effect of high blood glucose on nephrin endocytosis. In C57BL/6 mice, hyperglycemia over 24 h caused a significant increase in urinary albumin excretion, supporting the concept of the rapid impact of hyperglycemia on glomerular permselectivity. In summary, we have provided a molecular model of hyperglycemia-induced nephrin endocytosis and subsequent proteinuria and highlighted PKCα and PICK1 as promising therapeutic targets for diabetic nephropathy.

Protective effects of PPARγ agonist in acute nephrotic syndrome.

BACKGROUND: Peroxisome proliferator-activated receptor gamma (PPARγ) agonists have beneficial effects on renal structure and function in models of diabetes and chronic kidney diseases. However, the increased incidence of weight gain and edema potentially limits their usefulness. We studied an acute minimal-change disease-like nephrotic syndrome model to assess effects of PPARγ agonist on acute podocyte injury and effects on fluid homeostasis. METHODS: Acute podocyte injury and nephrotic syndrome were induced by puromycin aminonucleoside (PAN) injection in rats. RESULTS: PPARγ agonist, given at the time or after, but not before PAN, reduced proteinuria, restored synaptopodin, decreased desmin and trended to improve foot process effacement. There was no significant difference in glomerular filtration, effective circulating volume, blood pressure or fractional sodium excretion. PAN-injured podocytes had decreased PPARγ, less nephrin and α-actinin-4, more apoptosis and reduced phosphorylated Akt. In PAN-injured cultured podocytes, PPARγ agonist also reversed abnormalities only when given simultaneously or after injury. CONCLUSIONS: These results show that PPARγ agonist has protective effects on podocytes in acute nephrotic syndrome without deleterious effects on fluid homeostasis. PPARγ agonist-induced decrease in proteinuria in acute nephrotic syndrome is dependent at least partially on regulation of peroxisome proliferator-response element-sensitive gene expression such as α-actinin-4 and nephrin and the restoration of podocyte structure.

Prorenin receptor is essential for podocyte autophagy and survival.

The prorenin receptor (PRR) is highly expressed in podocytes, but its role in the maintenance of podocyte function is unknown. Here we generated podocyte-specific PRR-knockout mice and found that these animals died between 2 to 3 wk after birth. Within 14 d, PRR-knockout mice developed nephrotic syndrome, albuminuria with podocyte foot-process fusion, and cytoskeletal changes. Podocyte-specific PRR deletion also led to disturbed processing of multivesicular bodies and enrichment of autophagosomal (LC3) and lysosomal (LAMP2) markers, indicating a functional block in autophagosome-lysosome fusion and an overload of the proteasomal protein-degradation machinery. In vitro, PRR knockdown and pharmacologic blockade of vacuolar H(+)-ATPases, which associate with the PRR, increased vesicular pH, led to accumulation of LC3-positive and LAMP2-positive vesicles and altered the cytoskeleton. Taken together, these results suggest that the PRR is essential for podocyte function and survival by maintaining autophagy and protein-turnover machinery. Furthermore, PRR contributes to the control of lysosomal pH, which is important for podocyte survival and cytoskeletal integrity.

The PPARgamma agonist pioglitazone ameliorates aging-related progressive renal injury.

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists not only improve metabolic abnormalities of diabetes and consequent diabetic nephropathy, but they also protect against nondiabetic chronic kidney disease in experimental models. Here, we found that the PPAR-gamma agonist pioglitazone protected against renal injury in aging; it reduced proteinuria, improved GFR, decreased sclerosis, and alleviated cell senescence. Increased local expression of PPAR-gamma paralleled these changes. Underlying mechanisms included increased expression of klotho, decreased systemic and renal oxidative stress, and decreased mitochondrial injury. Pioglitazone also regulated p66(Shc) phosphorylation, which integrates many signaling pathways that affect mitochondrial function and longevity, by reducing protein kinase C-beta. These results suggest that PPAR-gamma agonists may benefit aging-related renal injury by improving mitochondrial function.

Role of α2-Adrenoceptors in Hypertension: Focus on Renal Sympathetic Neurotransmitter Release, Inflammation, and Sodium Homeostasis.

The kidney is extensively innervated by sympathetic nerves playing an important role in the regulation of blood pressure homeostasis. Sympathetic nerve activity is ultimately controlled by the central nervous system (CNS). Norepinephrine, the main sympathetic neurotransmitter, is released at prejunctional neuroeffector junctions in the kidney and modulates renin release, renal vascular resistance, sodium and water handling, and immune cell response. Under physiological conditions, renal sympathetic nerve activity (RSNA) is modulated by peripheral mechanisms such as the renorenal reflex, a complex interaction between efferent sympathetic nerves, central mechanism, and afferent sensory nerves. RSNA is increased in hypertension and, therefore, critical for the perpetuation of hypertension and the development of hypertensive kidney disease. Renal sympathetic neurotransmission is not only regulated by RSNA but also by prejunctional α2-adrenoceptors. Prejunctional α2-adrenoceptors serve as autoreceptors which, when activated by norepinephrine, inhibit the subsequent release of norepinephrine induced by a sympathetic nerve impulse. Deletion of α2-adrenoceptors aggravates hypertension ultimately by modulating renal pressor response and sodium handling. α2-adrenoceptors are also expressed in the vasculature, renal tubules, and immune cells and exert thereby effects related to vascular tone, sodium excretion, and inflammation. In the present review, we highlight the role of α2-adrenoceptors on renal sympathetic neurotransmission and its impact on hypertension. Moreover, we focus on physiological and pathophysiological functions mediated by non-adrenergic α2-adrenoceptors. In detail, we discuss the effects of sympathetic norepinephrine release and α2-adrenoceptor activation on renal sodium transporters, on renal vascular tone, and on immune cells in the context of hypertension and kidney disease.

Real-world data confirm the effectiveness of caplacizumab in acquired thrombotic thrombocytopenic purpura.

Acquired thrombotic thrombocytopenic purpura (aTTP) is a rare but life-threatening condition. In 2018, the nanobody caplacizumab was approved for the treatment of adults experiencing an acute episode of aTTP, in conjunction with plasma exchange (PEX) and immunosuppression for a minimum of 30 days after stopping daily PEX. We performed a retrospective, observational analysis on the use of caplacizumab in 60 patients from 29 medical centers in Germany during acute disease management. Caplacizumab led to a rapid normalization of the platelet count (median, 3 days; mean 3.78 days). One patient died after late treatment initiation due to aTTP-associated complications. In 2 patients with initial disease presentation and in 4 additional patients with laboratory signs of an exacerbation or relapse after the initial therapy, PEX-free treatment regimens could be established with overall favorable outcome. Caplacizumab is efficacious in the treatment of aTTP independent of timing and ancillary treatment modalities. Based on this real-world experience and published literature, we propose to administer caplacizumab immediately to all patients with an acute episode of aTTP. Treatment decisions regarding the use of PEX should be based on the severity of the clinical presentation and known risk factors. PEX might be dispensable in some patients.

ADAMTS13 and VWF activities guide individualized caplacizumab treatment in patients with aTTP.

Introduction of the nanobody caplacizumab was shown to be effective in the treatment of acquired thrombotic thrombocytopenic purpura (aTTP) in the acute setting. The official recommendations include plasma exchange (PEX), immunosuppression, and the use of caplacizumab for a minimum of 30 days after stopping daily PEX. This study was a retrospective, observational analysis of the use of caplacizumab in 60 patients from 29 medical centers in Germany. Immunosuppressive treatment led to a rapid normalization of ADAMTS13 activities (calculated median, 21 days). In 35 of 60 patients, ADAMTS13 activities started to normalize before day 30 after PEX; in 11 of 60 patients, the treatment was extended beyond day 30; and in 5 patients, it was extended even beyond day 58 due to persistent autoimmune activity. In 34 of 60 instances, caplacizumab was stopped before day 30 with a favorable outcome whenever ADAMTS13 activities were >10%. In contrast, 11 of 34 patients with ADAMTS13 activities <10% at the time of stopping caplacizumab treatment developed a nonfavorable outcome (disease exacerbation or relapse). In some cases, prolongation of the treatment interval to every other day was feasible and resulted in a sustained reduction of von Willebrand factor activity. ADAMTS13 activity measurements are central for a rapid diagnosis in the acute setting but also to tailor disease management. An ADAMTS13 activity-guided approach seems safe for identifying the individual time point when to stop caplacizumab to prevent overtreatment and undertreatment; this approach will result in significant cost savings without jeopardizing the well-being of patients. In addition, von Willebrand factor activity may serve as a biomarker for drug monitoring.

Highly Sensitive Measurement of Glomerular Permeability in Mice with Fluorescein Isothiocyanate-polysucrose 70.

The loss of albumin in urine (albuminuria) predicts cardiovascular outcome. Under physiological conditions, small amounts of albumin are filtered by the glomerulus and reabsorbed in the tubular system up until the absorption limit is reached. Early increases in pathological albumin filtration may, thus, be missed by analyzing albuminuria. Therefore, the use of tracers to test glomerular permselectivity appears advantageous. Fluorescently labeled tracer fluorescein isothiocyanate (FITC)-polysucrose (i.e., FITC-Ficoll), can be used to study glomerular permselectivity. FITC-polysucrose molecules are freely filtered by the glomerulus but not reabsorbed in the tubular system. In mice and rats, FITC-polysucrose has been investigated in models of glomerular permeability by using technically complex procedures (i.e., radioactive measurements, high-performance liquid chromatography [HPLC], gel filtration). We have modified and facilitated a FITC-polysucrose tracer-based protocol to test early and small increases in glomerular permeability to FITC-polysucrose 70 (size of albumin) in mice. This method allows repetitive urine analyses with small urine volumes (5 µL). This protocol contains information on how the tracer FITC-polysucrose 70 is applied intravenously and urine is collected via a simple urinary catheter. Urine is analyzed via a fluorescence plate reader and normalized to a urine concentration marker (creatinine), thereby avoiding technically complex procedures.

Isolation of Glomeruli and In Vivo Labeling of Glomerular Cell Surface Proteins.

Proteinuria results from the disruption of the glomerular filter that is composed of the fenestrated endothelium, glomerular basement membrane, and podocytes with their slit diaphragms. The delicate structure of the glomerular filter, especially the slit diaphragm, relies on the interplay of diverse cell surface proteins. Studying these cell surface proteins has so far been limited to in vitro studies or histologic analysis. Here, we present a murine in vivo biotinylation labeling method, which enables the study of glomerular cell surface proteins under physiologic and pathophysiologic conditions. This protocol contains information on how to perfuse mouse kidneys, isolate glomeruli, and perform endogenous immunoprecipitation of a protein of interest. Semi-quantitation of glomerular cell surface abundance is readily available with this novel method, and all proteins accessible to biotin perfusion and immunoprecipitation can be studied. In addition, isolation of glomeruli with or without biotinylation enables further analysis of glomerular RNA and protein as well as primary glomerular cell culture (i.e., primary podocyte cell culture).

Angiotensin II increases glomerular permeability by ß-arrestin mediated nephrin endocytosis.

Glomerular permeability and subsequent albuminuria are early clinical markers for glomerular injury in hypertensive nephropathy. Albuminuria predicts mortality and cardiovascular morbidity. AT1 receptor blockers protect from albuminuria, cardiovascular morbidity and mortality. A blood pressure independent, molecular mechanism for angiotensin II (Ang II) dependent albuminuria has long been postulated. Albuminuria results from a defective glomerular filter. Nephrin is a major structural component of the glomerular slit diaphragm and its endocytosis is mediated by ß-arrestin2. Ang II stimulation increases nephrin-ß-arrestin2 binding, nephrin endocytosis and glomerular permeability in mice. This Ang II effect is mediated by AT1-receptors. AT1-receptor mutants identified G-protein signaling to be essential for this Ang II effect. Gαq knockdown and phospholipase C inhibition block Ang II mediated enhanced nephrin endocytosis. Nephrin Y1217 is the critical residue controlling nephrin binding to ß-arrestin under Ang II stimulation. Nephrin Y1217 also mediates cytoskeletal anchoring to actin via nck2. Ang II stimulation decreases nephrin nck2 binding. We conclude that Ang II weakens the structural integrity of the slit diaphragm by increased nephrin endocytosis and decreased nephrin binding to nck2, which leads to increased glomerular permeability. This novel molecular mechanism of Ang II supports the use of AT1-receptor blockers to prevent albuminuria even in normotensives.

The renin-angiotensin receptor blocker azilsartan medoxomil compared with the angiotensin-converting enzyme inhibitor ramipril in clinical trials versus routine practice: insights from the prospective EARLY registry.

BACKGROUND: Patient characteristics and blood pressure-related outcomes in randomized clinical trials (RCTs) differ from clinical practice because of stringent selection criteria. The present study aimed to explore the relationship between clinical trials and clinical practice. We analyzed data from patients enrolled in the "Treatment with Azilsartan Compared to ACE-Inhibitors in Anti-Hypertensive Therapy" (EARLY) registry comparing blood pressure (BP) effects of the angiotensin receptor blocker (ARB) azilsartan medoxomil (AZL-M) with the angiotensin-converting enzyme (ACE) inhibitor ramipril between patients who met the eligibility criteria of a previous RCT and those who did not. METHODS: Patients with primary arterial hypertension were consecutively enrolled from primary care offices in Germany into the EARLY registry in a 7:3 ratio for treatment with AZL-M or an ACE inhibitor, provided that they met the following criteria at baseline: 1) no antihypertensive treatment prior to inclusion or a non-renin-angiotensin system (RAS) based monotherapy; 2) initiation of treatment with either AZL-M or an ACE inhibitor alone. Analyses were performed to evaluate BP effects for patients in the EARLY registry who met the selection criteria of a prior RCT (RCT+) versus those who did not (RCT-). RESULTS: Out of 3,698 patients considered, 1,644 complied with the RCT criteria (RCT+) while 2,054 did not (RCT-). RCT- patients (55.5%) displayed a higher risk profile in terms of age and comorbidities, and a wider spectrum of BP values at baseline, as highlighted by the grades of hypertension and mean BP values. The proportion of patients who achieved target blood pressure control in the RCT+ group was significantly higher for AZL-M versus ramipril (64.1 versus 56.1%; P<0.01), in accordance with the result of the clinical trial. In the RCT- AZL-M group, the proportion of patients who met BP targets was lower (58.1%) than in the RCT+ AZL-M group (64.1%), whereas the proportion of patients with target BP values in the RCT- ramipril and the RCT+ ramipril groups was similar (57.7 versus 56.1%). Thus, in contrast to results for the RCT+ group, in the RCT- group, the target BP attainment rate for AZL-M was not significantly superior to that for ramipril. However, the tolerability profile of AZL-M and ramipril was comparable in both populations. At the 12-month follow-up, death and stroke rates were low (≤0.5%) and adverse events did not differ between the AZL-M and ramipril groups, irrespective of RCT eligibility. CONCLUSIONS: These data confirm that the EARLY population comprised a broader spectrum of hypertensive patients than RCTs, and the differences in patient characteristics were accompanied by disparate rates of blood pressure goal attainment. Overall, the validity of the RCT was demonstrated and confirmed in clinical practice with a broader range of patients with various comorbidities.