A randomized controlled pilot trial of anakinra and pioglitazone for protein metabolism in patients on maintenance haemodialysis

BACKGROUND

Chronic inflammation and insulin resistance are highly prevalent in patients on maintenance haemodialysis (MHD) and are strongly associated with protein energy wasting. We conducted a pilot, randomized, placebo-controlled trial of recombinant human interleukin-1 receptor antagonist (IL-1ra) and pioglitazone to explore the safety, feasibility and efficacy for insulin-mediated protein metabolism in patients undergoing MHD.

METHODS

Twenty-four patients were randomized to receive IL-1ra, pioglitazone or placebo for 12 weeks. Changes in serum inflammatory markers and insulin-mediated protein synthesis, breakdown and net balance in the whole-body and skeletal muscle compartments were assessed using hyperinsulinaemic-hyperaminoacidemic clamp technique at baseline and Week 12.

RESULTS

Among 24 patients, median (interquartile range) age was 51 (40, 61), 79% were African American and 21% had diabetes mellitus. All patients initiated on intervention completed the study, and no serious adverse events were observed. There was a statistically significant decrease in serum high-sensitivity C-reactive protein in the pioglitazone group compared with placebo, but not in the IL-1ra group. No significant differences in the changes of whole-body or skeletal muscle protein synthesis, breakdown and net balance were found between the groups.

CONCLUSIONS

In this pilot study, there were no statistically significant effects of 12 weeks of IL-1ra or pioglitazone on protein metabolism in patients on MHD.

CLINICALTRIALS

gov registration: NCT02278562.

Treatment of Acute Myeloid Leukemia in Older Adults

Acute Myeloid Leukemia (AML) is an aggressive myeloid malignancy predominantly affecting older adults. Despite the advancements in new therapies for AML, older and medically unfit patients continue to suffer from poor outcomes due to disease-related factors such as the mutational profile and patient-related factors such as comorbidities and performance status. In this review, we discuss a spectrum of therapeutic options for older patients with AML starting with a historical perspective and ending with therapies being investigated in clinical trials. We review the standard of care treatment options including combination venetoclax and hypomethylating agents, in addition to targeted therapies such as FLT3 and IDH inhibitors. Lastly, we shed light on challenges facing the care of older adults and their representation in clinical trials.

High tissue-sodium associates with systemic inflammation and insulin resistance in obese individuals

BACKGROUND AND AIMS

High sodium intake is associated with obesity and insulin resistance, and high extracellular sodium content may induce systemic inflammation, leading to cardiovascular disease. In this study, we aim to investigate whether high tissue sodium accumulation relates with obesity-related insulin resistance and whether the pro-inflammatory effects of excess tissue sodium accumulation may contribute to such association.

METHODS AND RESULTS

In a cross-sectional study of 30 obese and 53 non-obese subjects, we measured insulin sensitivity determined as glucose disposal rate (GDR) using hyperinsulinemic euglycemic clamp, and tissue sodium content using ²³Na magnetic resonance imaging. Median age was 48 years, 68% were female and 41% were African American. Median (interquartile range) BMI was 33 (31.5, 36.3) and 25 (23.5, 27.2) kg/m² in the obese and non-obese individuals, respectively. In obese individuals, insulin sensitivity negatively correlated with muscle (r = -0.45, p = 0.01) and skin sodium (r = -0.46, p = 0.01). In interaction analysis among obese individuals, tissue sodium had a greater effect on insulin sensitivity at higher levels of high-sensitivity C-reactive protein (p-interaction = 0.03 and 0.01 for muscle and skin Na+, respectively) and interleukin-6 (p-interaction = 0.024 and 0.003 for muscle and skin Na+, respectively). In interaction analysis of the entire cohort, the association between muscle sodium and insulin sensitivity was stronger with increasing levels of serum leptin (p-interaction = 0.01).

CONCLUSIONS

Higher muscle and skin sodium are associated with insulin resistance in obese patients. Whether high tissue sodium accumulation has a mechanistic role in the development of obesity-related insulin resistance through systemic inflammation and leptin dysregulation remains to be examined in future studies.

CLINICALTRIALS

gov registration: NCT02236520.

Time from diagnosis to treatment is associated with survival in patients with acute myeloid leukaemia: An analysis of 55 985 patients from the National Cancer Database

Acute myeloid leukaemia (AML) is conventionally thought of as a medical emergency. However, several studies on the association of time from diagnosis to treatment with survival did not have concordant results. Here we analyse 55 985 AML patients from the National Cancer Database, and we show that in patients less than 60 years old a five-day delay in chemotherapy initiation leads to worse long-term survival. The difference is small [hazard ratio (HR) 1.05, 95% confidence interval (CI) 1.01-1.09 in multivariate analysis] but statistically significant. This study raises the issue of power to detect small differences in retrospective studies.

Efficacy and Safety of Direct Oral Anticoagulants in Patients With Antiphospholipid Syndrome: A Systematic Review and Meta-Analysis

Due to a high risk of recurrent thromboembolism in patients with antiphospholipid syndrome (APS), long-term anticoagulation is recommended. For decades, vitamin K antagonists (VKAs) have been the gold standard for thromboprophylaxis in these patients. Due to the widespread use of direct oral anticoagulants (DOACs) in various thromboembolic conditions and their potential advantages compared to VKAs, several studies have been conducted to evaluate their safety and efficacy in APS.

We performed a literature search using PubMed, Embase, and Cochrane databases for studies comparing DOACs to VKAs in patients with APS. Relative risk (RR) and the corresponding 95% confidence intervals (95% CI) were estimated for recurrent thromboembolic events, bleeding, and mortality.

A total of 1437 patients pooled from 12 studies were analyzed. The risk of recurrent thrombosis, especially arterial thrombosis, doubled with DOACs compared to VKAs (RR 2.61, 95% CI 1.44-4.71; p=0.001). The risk further increased in patients with a triple-positive antiphospholipid antibody profile (RR 4.50, 95% CI 1.91-10.63; p=0.0006) and with the use of rivaroxaban (RR 1.95, 95% CI 1.10-3.45; p=0.02). The risk of major bleeding and mortality were not significantly different between the two arms. A trend favoring DOACs compared to VKAs was observed for all bleeding events. 

This meta-analysis comes in agreement with previous studies and supports the use of VKAs in APS. Our study revealed that VKAs remain the gold standard for the management of APS, especially triple-positive APS. DOACs, particularly rivaroxaban, are not as effective in preventing recurrent thromboembolism in high-risk APS patients. Further studies are needed to evaluate the role of DOACs apart from rivaroxaban with a focus on their efficacy in the management of isolated or double-positive APS.

Tissue Sodium in Patients With Early Stage Hypertension: A Randomized Controlled Trial

Background

Sodium (Na⁺) stored in skin and muscle tissue is associated with essential hypertension. Sodium magnetic resonance imaging is a validated method of quantifying tissue stores of Na⁺. In this study, we evaluated tissue Na⁺ in patients with elevated blood pressure or stage I hypertension in response to diuretic therapy or low Na⁺ diet.

Methods and Results

In a double‐blinded, placebo‐controlled trial, patients with systolic blood pressure 120 to 139 mm Hg were randomized to low sodium diet (<2 g of sodium), chlorthalidone, spironolactone, or placebo for 8 weeks. Muscle and skin Na⁺ using sodium magnetic resonance imaging and pulse wave velocity were assessed at the beginning and end of the study. Ninety‐eight patients were enrolled to undergo baseline measurements and 54 completed randomization. Median baseline muscle and skin Na⁺ in 98 patients were 16.4 mmol/L (14.9, 18.9) and 13.1 mmol/L (11.1, 16.1), respectively. After 8 weeks, muscle Na⁺ increased in the diet and chlorthalidone arms compared with placebo. Skin sodium was decreased only in the diet arm compared with placebo. These associations remained significant after adjustment for age, sex, body mass index, systolic blood pressure, and urinary sodium. No changes were observed in pulse wave velocity among the different groups when compared with placebo.

Conclusions

Diuretic therapy for 8 weeks did not decrease muscle or skin sodium or improve pulse wave velocity in patients with elevated blood pressure or stage I hypertension.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02236520.

Effect Modification of Body Mass Index and Kidney Function on Insulin Sensitivity Among Patients With Moderate CKD and Healthy Controls

Introduction

Insulin resistance and obesity are prevalent in chronic kidney disease (CKD) patients. The interaction of body mass index (BMI) and kidney function across the continuum of estimated glomerular filtration rate (eGFR) is unknown.

Methods

In a cross-sectional study of 139 patients, 52 with CKD stages 3 and 4 and 87 patients with normal eGFR, we measured the insulin sensitivity index (ISI) using the hyperinsulinemic euglycemic clamp and homeostasis model assessment of insulin resistance (HOMA-IR). We investigated the interaction between eGFR and BMI in their association with ISI and HOMA-IR using linear models with robust standard errors.

Results

Median age was 56 (42, 66) years, 50.4% were female, and 36% were African American. Patients with low eGFR (∼30 ml/min per 1.73 m²) had low ISI (2.3 mg/min per μU/ml) regardless of BMI. Among patients with preserved eGFR (>90 ml/min per 1.73m²), BMI had a greater effect on ISI (6.3 mg/min per μU/ml at a BMI of 20 kg/m² vs. 4.6 mg/min per μU/ml at a BMI of 30 kg/m²) (P for interaction = 0.046). In models adjusted for demographics, and log transformed interleukin-6, high-sensitivity C-reactive protein, leptin, and adiponectin, a 1-SD (28 ml/min per 1.73 m²) lower eGFR was associated with a statistically significant 1.14-unit decrease in ISI (95% confidence interval = −1.80, −0.48) among nonobese patients. Among obese patients, the effect estimate was −0.25 (95% confidence interval = −0.88, 0.39). The association between BMI and HOMA-IR was stronger in patients with lower eGFR (P for interaction = 0.005).

Conclusion

Both eGFR and BMI are independently associated with insulin sensitivity, but the strength of the association between BMI and insulin sensitivity varies significantly across eGFR.

Peripheral Insulin Resistance Is Associated with Copeptin in Patients with Chronic Kidney Disease

Background

Insulin resistance is associated with cardiovascular disease risk and worsened kidney function. Patients with CKD have higher levels of insulin resistance. Elevated levels of copeptin (a surrogate for vasopressin levels) have been associated with an increased incidence and progression of CKD, and with incident diabetes mellitus. The purpose of our study was to examine the relationship between insulin resistance, copeptin, and CKD.

Methods

We performed a cross-sectional study to investigate if insulin resistance was associated with higher copeptin levels in nondiabetic patients with stage 3-4 CKD versus controls. We measured plasma copeptin levels and used data from 52 patients with stage 3-4 CKD and 85 controls (eGFR ≥60 ml/min per 1.73 m²) enrolled in the Insulin Resistance in Chronic Kidney Disease (IRCKD) study. We then used a multivariable linear-regression model to assess the independent relationship between peripheral or hepatic insulin resistance and copeptin across levels of eGFR.

Results

We found that in patients with CKD (eGFR of 30-60 ml/min per 1.73 m²), but not in controls, peripheral insulin resistance was significantly correlated with higher levels of log copeptin (r=-0.21, P=0.04). In patients with CKD, when adjusted for age, sex, BMI, serum osmolality, log IL6, and log leptin/adiponectin ratio, each 1 SD decrease in insulin sensitivity was associated with a 39% increase in serum copeptin levels. The relationship between hepatic insulin resistance, copeptin, and eGFR is similar between controls and patients with reduced eGFR.

Conclusion

Peripheral insulin resistance is associated with elevated copeptin levels in nondiabetic patients with stage 3-4 CKD. Further research into how the interaction between peripheral insulin resistance and elevated vasopressin affects CKD progression could be of interest.

Sodium activates human monocytes via the NADPH oxidase and isolevuglandin formation

AIMS

Prior studies have focused on the role of the kidney and vasculature in salt-induced modulation of blood pressure; however, recent data indicate that sodium accumulates in tissues and can activate immune cells. We sought to examine mechanisms by which salt causes activation of human monocytes both in vivo and in vitro.

METHODS AND RESULTS

To study the effect of salt in human monocytes, monocytes were isolated from volunteers to perform several in vitro experiments. Exposure of human monocytes to elevated Na+ex vivo caused a co-ordinated response involving isolevuglandin (IsoLG)-adduct formation, acquisition of a dendritic cell (DC)-like morphology, expression of activation markers CD83 and CD16, and increased production of pro-inflammatory cytokines tumour necrosis factor-α, interleukin (IL)-6, and IL-1β. High salt also caused a marked change in monocyte gene expression as detected by RNA sequencing and enhanced monocyte migration to the chemokine CC motif chemokine ligand 5. NADPH-oxidase inhibition attenuated monocyte activation and IsoLG-adduct formation. The increase in IsoLG-adducts correlated with risk factors including body mass index, pulse pressure. Monocytes exposed to high salt stimulated IL-17A production from autologous CD4+ and CD8+ T cells. In addition, to evaluate the effect of salt in vivo, monocytes and T cells isolated from humans were adoptively transferred to immunodeficient NSG mice. Salt feeding of humanized mice caused monocyte-dependent activation of human T cells reflected by proliferation and accumulation of T cells in the bone marrow. Moreover, we performed a cross-sectional study in 70 prehypertensive subjects. Blood was collected for flow cytometric analysis and 23Na magnetic resonance imaging was performed for tissue sodium measurements. Monocytes from humans with high skin Na+ exhibited increased IsoLG-adduct accumulation and CD83 expression.

CONCLUSION

Human monocytes exhibit co-ordinated increases in parameters of activation, conversion to a DC-like phenotype and ability to activate T cells upon both in vitro and in vivo sodium exposure. The ability of monocytes to be activated by sodium is related to in vivo cardiovascular disease risk factors. We therefore propose that in addition to the kidney and vasculature, immune cells like monocytes convey salt-induced cardiovascular risk in humans.

KD-PACE Salvage Therapy for Aggressive Relapsed Refractory Multiple Myeloma, Plasma Cell Leukemia and Extramedullary Myeloma

BACKGROUND

Patients with advanced/aggressive multiple myeloma have limited treatment options to achieve rapid disease control. In eligible patients, bortezomib, dexamethasone, thalidomide, cisplatin, doxorubicin, cyclophosphamide, and etoposide is often used. However, many patients are refractory to or have toxicities from bortezomib and there is a need for bridging therapy. We have used a modified regimen incorporating the second-generation proteasome inhibitor carfilzomib (carfilzomib, dexamethasone, thalidomide, cisplatin, doxorubicin, cyclophosphamide and etoposide [KD-PACE]) instead of bortezomib for relapsed/refractory multiple myeloma.

PATIENTS AND METHODS

This 2-center retrospective study included consecutive patients receiving KD-PACE for relapsed or refractory multiple myeloma, plasma cell leukemia, or extramedullary myeloma. The primary outcome was the feasibility of KD-PACE as a bridging therapy to a more definitive treatment option.

RESULTS

Fifty-two patients were included. The median age was 57 years, and 67% were male. Thirty-one patients were bridged with KD-PACE to autologous hematopoietic stem cell transplant (29%), allogenic hematopoietic stem cell transplant (27%), or a clinical trial (12%). Patients bridged to autologous hematopoietic stem cell transplant, allogenic hematopoietic stem cell transplant, or a clinical trial had a superior progression-free survival (8.3 months vs 2.3 months in the nonbridged group; P < .001) and overall survival (median, 16.7 months vs 4.3 months in the nonbridged group; P < .001). No unexpected toxicities occurred from the treatment regimen.

CONCLUSION

KD-PACE is a promising treatment option for select patients with advanced/aggressive forms of myeloma requiring rapid disease control before a more definitive salvage therapy such as auto/allotransplantation or a clinical trial.

Tissue sodium stores in peritoneal dialysis and hemodialysis patients determined by 23-sodium magnetic resonance imaging

BACKGROUND

Tissue sodium content in patients on maintenance hemodialysis (MHD) and peritoneal dialysis (PD) were previously explored using 23Sodium magnetic resonance imaging (23NaMRI). Larger studies would provide a better understanding of sodium stores in patients on dialysis as well as the factors influencing this sodium accumulation.

METHODS

In this cross-sectional study, we quantified the calf muscle and skin sodium content in 162 subjects (10 PD, 33 MHD patients, and 119 controls) using 23NaMRI. Plasma levels of interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) were measured to assess systemic inflammation. Sixty-four subjects had repeat 23NaMRI scans that were analyzed to assess the repeatability of the 23NaMRI measurements.

RESULTS

Patients on MHD and PD exhibited significantly higher muscle and skin sodium accumulation compared to controls. African American patients on dialysis exhibited greater muscle and skin sodium content compared to non-African Americans. Multivariable analysis showed that older age was associated with both higher muscle and skin sodium. Male sex was also associated with increased skin sodium deposition. Greater ultrafiltration was associated with lower skin sodium in patients on PD (Spearman's rho=-0.68, P = 0.035). Higher plasma IL-6 and hsCRP levels correlated with increased muscle and skin sodium content in the overall study population. Patients with higher baseline tissue sodium content exhibited greater variability in tissue sodium stores on repeat measurements.

CONCLUSIONS

Our findings highlight greater muscle and skin sodium content in dialysis patients compared to controls without kidney disease. Tissue sodium deposition and systemic inflammation seen in dialysis patients might influence one another bidirectionally.

Supervised Exercise Intervention and Overall Activity in CKD

INTRODUCTION

Patients are often instructed to engage in multiple weekly sessions of exercise to increase physical activity. We aimed to determine whether assignment to a supervised exercise regimen increases overall weekly activity in individuals with chronic kidney disease (CKD).

METHODS

We performed a secondary analysis of a pilot randomized 2 × 2 factorial design trial examining the effects of diet and exercise (10%-15% reduction in caloric intake, 3 supervised exercise sessions/wk, combined diet restriction/exercise, and control). Activity was measured as counts detected by accelerometer. Counts data were collected on all days for which an accelerometer was worn at baseline, month 2, and month 4 follow-up. The primary outcome was a relative change from baseline in log-transformed counts/min. Generalized estimating equations were used to compare the primary outcome in individuals in the exercise group and the nonexercise group.

RESULTS

We examined 111 individuals randomized to aerobic exercise or usual activity (n = 48 in the exercise group and n = 44 controls). The mean age was 57 years, 42% were female, and 28% were black. Median overall adherence over all time was 73%. Median (25th, 75th percentile) counts/min over nonsupervised exercise days at months 2 and 4 were 237.5 (6.5, 444.4) for controls and 250.9 (7.7, 529.8) for the exercise group (P = 0.74). No difference was observed in the change in counts/min between the exercise and control groups over 3 time points (β [fold change], 0.96, 95% confidence interval [CI], 0.91, 1.02).

CONCLUSION

Engaging in a supervised exercise program does not increase overall weekly physical activity in individuals with stage 3 to 4 CKD.

Effects of diet and exercise on adipocytokine levels in patients with moderate to severe chronic kidney disease

BACKGROUND AND AIMS

Obesity is a pro-inflammatory risk factor for progression of CKD and cardiovascular disease. We hypothesized that implementation of caloric restriction and endurance exercise would improve adipocytokine profiles in patients with moderate to severe CKD.

METHODS AND RESULTS

We enrolled patients with moderate to severe CKD through a multi-center pilot randomized trial of diet and exercise in a 4-arm design (dietary restriction of 10%-15% reduction in caloric intake, exercise three times/week, combined diet and exercise, and control) (NCT01150851). Adipocytokines (adiponectin and leptin) were measured at the beginning and end of the study period as secondary outcomes. Treatment effect was analyzed in a multivariable model adjusted for baseline outcome values, age, gender, site and diabetes. A total of 122 participants were consented, 111 were randomized (42% female, 25% diabetic, and 91% hypertensive), 104 started intervention and 92 completed the study (Figure 1). Plasma adiponectin levels increased significantly in response to diet by 23% (95% CI: 0.2%, 49.8%, p = 0.048) among participants randomized to the caloric restriction and usual activity arm but not to exercise, whereas circulating leptin did not change by either treatment.

CONCLUSION

Our data suggest that dietary caloric restriction increases plasma adiponectin levels in stage 3-4 CKD patients, with limited effect on leptin levels. These findings suggest the potential for improving the metabolic milieu of CKD with moderate calorie restriction.

Critical role of Interleukin 21 and T follicular helper cells in hypertension and vascular dysfunction

T and B cells have been implicated in hypertension, but the mechanisms by which they produce a coordinated response is unknown. T follicular helper (Tfh) cells that produce interleukin 21 (IL21) promote germinal center (GC) B cell responses leading to immunoglobulin (Ig) production. Here we investigate the role of IL21 and Tfh cells in hypertension. In response to angiotensin (Ang) II-induced hypertension, T cell IL21 production is increased, and Il21-/- mice develop blunted hypertension, attenuated vascular end-organ damage, and decreased interleukin 17A (IL17A) and interferon gamma production. Tfh-like cells and GC B cells accumulate in the aorta and plasma IgG1 is increased in hypertensive WT but not Il21-/-mice. Furthermore, Tfh cell deficient mice develop blunted hypertension and vascular hypertrophy in response to Ang II infusion. Importantly, IL21 neutralization reduces blood pressure (BP) and reverses endothelial dysfunction and vascular inflammation. Moreover, recombinant IL21 impairs endothelium-dependent relaxation ex vivo and decreases nitric oxide production from cultured endothelial cells. Finally, we show in humans that peripheral blood T cell production of IL21 correlates with systolic BP and IL17A production. These data suggest that IL21 may be a novel therapeutic target for the treatment of hypertension and its micro- and macrovascular complications.

Abstract 088: The Immune Mechanisms of Salt-Sensitivity

Salt-sensitivity is present in 50% of all hypertensive individuals. Prior studies have focused on the roles of kidney, vasculature and sympathetic activity in salt-sensitivity but the contribution of immune cells is poorly understood. We recently found that in murine dendritic cells amiloride sensitive channels sense salt and trigger NADPH oxidase-dependent formation of isolevuglandin-(IsolG)-adducts. We tested the hypothesis that human monocytes exhibit salt-sensitivity leading to activation via IsoLG-adduct formation and this is associated with cardiovascular risk factors. In a cohort of 18 subjects, we found that the sodium intake, measured by 24 hours urine excretion (UNa) was positively correlated with plasma levels of IsolGs. We also measured accumulation of interstitial sodium in 70 subjects by Magnetic Sodium Resonance and evaluated their circulating monocytes by flow cytometry. Subjects with high skin sodium had higher levels of IsoLGs in their monocytes (24±6 vs 38±6 %, p<0.05) and higher expression of CD83, an activation and dendritic cell marker (0.04 ± 0.009 vs 0.12± 0.04%, p =0.04). To investigate the ability of monocytes to respond to salt, we cultured monocytes from 17 subjects in high salt environment (HS:190 mM NaCl) or normal media (NS:150mM NaCl) for 48 hours. In culture, 47% of the subjects respond to salt, denoted by an increase of at least 20% in IsoLG formation (NS: 1327±240 vs. HS: 2217±653, p =0.009) as well as increased expression of the activation markers CD83 and CD86. The subjects’ cardiovascular risk factors including pulse pressure, BMI, glucose and total cholesterol positively correlated with the amount of IsolGs produced (ΔHS-NS) in response to salt (r=0.51 p<0.05, r=0.66 p=0.005, r=0.55 p<0.05, p=0.72 p=0.003, respectively). Interestingly, 5 pM of Ouabain, a Na-K-ATPase blocker, increased intracellular sodium and expression of CD86 (NS: 98±11, HS: 203 ±16 vs, NS+ Ouabain: 476 ± 58 MFI, p=0.001) and CD83 (NS: 778±90, HS: 1529 ± 94 vs, NS+ Ouabain: 1649 ± 209 MFI, p=0.003). We suggest that in addition to the kidney and vasculature, human monocytes and monocyte derived cells exhibit salt sensitivity, and that this is conveyed by cardiovascular risk factors and activity of the Na-K-ATPase.

Abstract 021: Interleukin-21 Plays a Critical Role in Hypertension and Vascular Dysfunction

T cell derived cytokines, interleukin 17A (IL17A) and interferon gamma (IFNg), promote angiotensin II (Ang II)-induced hypertension and end-organ damage. Interleukin 21 (IL21), produced primarily by T follicular helper (Tfh) cells, has been shown to induce IL17A and IFNγ production from T effector cells. IL21 is also a potent activator of germinal center (GC) B cells and immunoglobulin (Ig) class switching. We hypothesized that IL21 plays a fundamental role in hypertension and hypertensive end-organ damage through its effects on pro-inflammatory T cell polarization, vascular dysfunction, and enhanced Ig secretion. CD4+ T cells from Ang II infused WT mice exhibit 1.5-fold increased IL21 mRNA expression and 2-fold increased IL-21 production compared to vehicle. We found IL21 -/- mice exhibit a 30mmHg reduction in systolic blood pressure (SBP) in response to 4 weeks of Ang II infusion compared to age-matched wild type (WT) mice. Further, IFNg and IL17A production from CD8+ or CD4+ T cells, respectively, was abrogated in IL21 -/- mice vs. WT mice infused with Ang II. We also found Tfh cells and GC B cells significantly increased in the aortas and mesenteric vessels of Ang II WT mice but not IL21 -/- mice. Ang II induced an increase in percent of lymph node GC B cells and IgG/IgM ratio, consistent with Ig class switching. Ang II-induced increase in renal injury was also blunted in IL21 -/- mice vs. WT mice. Mesenteric vessels from IL21 -/- mice were protected from Ang II-induced endothelial dysfunction. IL21 -/- mice also developed blunted aortic fibrosis and reduced smooth muscle cell hypertrophy after 4 weeks of Ang II vs. WT mice. IL-21 neutralization beginning 2 weeks after Ang II resulted in a 15 mmHg reduction in SBP and reversal of aortic inflammation and vascular endothelial dysfunction compared to isotype control treated animals. Lastly, CD4+ T cell production of IL21 positively correlated with SBP in human volunteers, and in fact, IL-21 production was significantly higher in hypertensive compared to normotensive subjects. Taken together, these studies provide compelling evidence that IL21 may function as a master cytokine in the pathogenesis of hypertension and suggest that therapies targeting IL21 may reduce hypertension and the associated end-organ damage.

Acute effects of insulin on circulating natriuretic peptide levels in humans

Background

The natriuretic peptide hormones play an important role in salt and blood pressure regulation. In observational studies, obesity and insulin resistance have been consistently associated with lower concentrations of natriuretic peptides. It has been proposed that insulin influences natriuretic peptide production.

Objective

We sought to determine the acute effects of insulin administration on natriuretic peptide concentrations.

Methods

31 men and women (11 lean, 10 overweight, and 10 obese), ages 30–70 years, without cardiovascular disease or overt diabetes underwent a hyperinsulinemic-euglycemic insulin clamp. Plasma concentrations of N-terminal pro atrial natriuretic peptide (NT-proANP) and N-terminal pro B-type natriuretic peptide (NT-proBNP) were measured at baseline and steady-state (the final 30 minutes of the clamp protocol).

Results

From baseline to steady-state, insulin levels increased from a mean level of 9.5 to 176.7 μU/ml (p<0.001). Over this period, circulating NT-proANP concentrations decreased by 9% (-1933 ng/L, p = 0.01). The changes in NT-proANP did not differ between lean, overweight, and obese individuals. Steady-state NT-proANP levels, adjusted for baseline, were lower in individuals with greater insulin resistance, independent of BMI. In contrast to NT-proANP, NT-proBNP levels did not change significantly during the clamp (p = 0.41).

Conclusion

Insulin administration was associated with a moderate decrease in circulating NT-proANP, but not NT-proBNP. The lowest NT-proANP concentrations were found in insulin-resistant individuals. Further investigations are warranted to elucidate potential mechanisms underlying the effects of insulin on the cardiac hormonal axis.