Assessing Health-Related Quality of Life in Non-Directed Versus Directed Kidney Donors: Implications for the Promotion of Non-Directed Donation

Living kidney donation has increased significantly, but little is known about the post-donation health-related quality of life (HRQoL) of non-directed donors (NDs) vs. directed donors (DDs). We thus examined the outcomes of 112 living kidney donors (82 NDs, 30 DDs). For the primary outcomes-namely, the mean physical component summary (PCS) and mental component summary (MCS) scores of the 12-item Short Form Survey (SF-12) questionnaire-scores were significantly higher for the NDs vs. the DDs (PCS: +2.69, MCS: +4.43). For secondary outcomes, NDs had shorter hospital stays (3.4 vs. 4.4 days), returned to physical activity earlier (45 vs. 60 days), exercised more before and after donation, and continued physical activity post-donation. Regression analyses revealed that donor type and white blood cell count were predictive of the PCS-12 score, and donor type was predictive of the MCS-12 score. Non-directed donation was predictive of a shorter hospital stay (by 0.78 days, p < 0.001) and the odds of having PCS-12 and MCS-12 scores above 50 were almost 10 and 16 times higher for NDs, respectively (p < 0.05). These findings indicate the safety and potential benefits of promoting non-directed donation. However, careful selection processes must be maintained to prevent harm and exploitation.

The Long-Term Outcome of Kidney Transplant Recipients in the Eighth Decade Compared With Recipients in the Seventh Decade of Life

BACKGROUND

With the aging of the population, more older patients are being considered for kidney transplantation; therefore, it is crucial to evaluate the risks and benefits of transplantation in this population. This study aimed to assess long-term outcomes of kidney transplantation in a cohort of patients who underwent kidney transplantation at age >70 years, compared with patients aged 60 to 69 years at transplantation.

METHODS

Included in the study were 261 consecutive kidney transplant recipients: 52 were aged >70 years, and 209 were aged 60 to 69 years at transplantation. Data were collected retrospectively and analyzed using multivariate logistic regression to identify potential outcome risk factors.

RESULTS

The number of transplants in both groups increased during the study period. Mortality after transplantation was strongly correlated to age (hazard ratio [HR] = 1.11; 95% CI, 1.05-1.18; P < .001), deceased donor (HR = 2.0; 95% CI, 1.1-3.8; P = .034), and pretransplant diabetes (HR = 2.9; 95% CI, 1.7-4.9; P = .001). Recipients aged >70 years had an increased risk of death censored graft failure (HR = 2.98; 95% CI, 1.56-5.74; P = .001). In living donor transplants, 3-year survival was 80% in recipients age >70 years, compared with 98% in the 60- to 69-year group. Five-year survival was 71% and 92%, respectively. In deceased donor transplants, 3-year survival was 63% and 78%, and 5-year survival was 58% and 72%, respectively. The risk of malignancy (excluding nonmelanotic skin cancer) was nearly triple in the age >70 years group (HR = 2.96; 95% CI, 1.3-6.8; P = .01).

CONCLUSIONS

Patient and graft survival in kidney recipients in the eighth decade is worse compared with recipients in the seventh decade of life. However, it is improved with living kidney donation.

Clinical efficacy of the fourth dose of the BNT162b2 vaccine in maintenance dialysis patients

BACKGROUND AND OBJECTIVES

Highly effective vaccines against severe acute respiratory syndrome virus 2 have been developed and administered worldwide. However, protection from coronavirus disease 2019 is not absolute and an optimal vaccination regimen needs to be established. This study assessed the clinical efficacy of the coronavirus disease 2019 vaccine among dialysis patients receiving 3 or 4 doses of vaccine.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

This retrospective study was conducted using the electronic database of Clalit Health Maintenance Organization in Israel. Chronic dialysis patients treated with either hemodialysis or peritoneal dialysis during the coronavirus disease 2019 pandemic were included. We compared clinical outcomes of patients who had received three or four doses of the severe acute respiratory syndrome virus 2 vaccine.

RESULTS

This study included 1,030 patients on chronic dialysis, with a mean age of 68 ± 13 years. Among them, 502 patients had received 3 doses of the vaccine and 528 received 4 doses. Severe acute respiratory syndrome virus 2 infection rates, severe COVID-19 that resulted in hospitalizations, COVID-19-related mortality and all-cause mortality rates were lower among chronic dialysis patients who received a fourth dose of vaccine as compared to those who received only 3 doses (after controlling for age, sex and comorbidities). Despite lower mortality rates observed with the Omicron variant, the fourth dose was significantly associated with reduced COVID-19-related mortality (1.7% vs. 3.8%, p = 0.04). Odds ratio for COVID-19-related mortality was 0.44 with 95% CI 0.2-0.98.

CONCLUSIONS

As seen in the general population and with previous vaccine boosters, the fourth dose of the BNT162b2 vaccine reduced rates of severe COVID-19-related hospitalization and mortality among chronic dialysis patients. Further studies are needed to establish the optimal regimens of vaccination for patients on chronic dialysis.

Dialysis modality, humoral response to vaccine, and SARS-CoV-2 infection risk: Comparative prospective evaluation

BACKGROUND

COVID-19 vaccinations have a central role in decreasing severe SARS-CoV-2 disease complications. This study investigated the long-term humoral immune response to BNT162b2 vaccine among hemodialysis (HD) versus peritoneal dialysis (PD) patients, and their relative risk for COVID-19 infection.

METHODS

This prospective, observational study included maintenance HD and PD patients who had received at least two BNT162b2 vaccine doses. Levels of antibodies targeting SARS-CoV-2 spike protein were measured 6 and 12 months after the first vaccine dose, and 2-3 weeks after the third and fourth vaccine doses. Patients were divided according to dialysis modality (HD or PD). Humoral response was evaluated at different time points among different vaccine regimens (two vs. three vs. four doses of vaccine). An adjusted multivariate model was used to assess cumulative risk for SARS-CoV-2 infection.

RESULTS

Eighty-seven HD and 36 PD patients were included. Among them, 106 (86%) received at least three vaccine doses. Both HD and PD patients demonstrated marked increases in humoral response 2-3 weeks after the third dose (mean anti-S antibody increased from 452 ± 501 AU/mL to 19,556 ± 14,949 AU/mL, p < 0.001). By 6 months after the third dose, antibody titers had declined significantly (mean anti-S antibody 9841 ± 10,493 AU/mL, p < 0.001). HD patients had higher risk for SARS-CoV-2 infection than PD patients (OR 4.4 [95% CI 1.4-13.6], p = 0.006). In multivariate analysis, the most important predictor for SARS-CoV-2 infection was dialysis modality.

CONCLUSION

This study found a high antibody response rate after the third and fourth doses of BNT162b2 vaccine among dialysis patients. Hemodialysis as dialysis modality is an important predictor of COVID-19 infection, despite similar humoral responses to vaccine in peritoneal dialysis.

The Clinical Significance of LDL-Cholesterol on the Outcomes of Hemodialysis Patients with Acute Coronary Syndrome

Background and objectives: Dyslipidemia is one of the most important modifiable risk factors in the pathogenesis of cardiovascular disease in the general population, but its importance in the hemodialysis (HD) population is uncertain. Materials and Methods: This retrospective cohort study includes HD patients hospitalized due to acute coronary syndrome (ACS) in the period 2015-2020 with lipid profile data during ACS. A control group with preserved kidney function was matched. Risk factors for 30-day and 1-year mortality were assessed. Results: Among 349 patients included in the analysis, 246 were HD-dependent ("HD group"). HD group patients had higher prevalence of diabetes, hypertension, and heart disease than the control group. At ACS hospitalization, lipid profile and chronic statin treatment were comparable between groups. Odds ratios for 30-day mortality in HD vs. control group was 5.2 (95% CI 1.8-15; p = 0.002) and for 1-year, 3.4 (95% CI 1.9-6.1; p <0.001). LDL and LDL < 70 did not change 30-day and 1-year mortality rates in the HD group (p = 0.995, 0.823, respectively). However, survival after ACS in HD patients correlated positively with nutritional parameters such as serum albumin (r = 0.368, p < 0.001) and total cholesterol (r = 0.185, p < 0.001), and inversely with the inflammatory markers C-reactive protein (CRP; r = -0.348, p < 0.001) and neutrophils-to-lymphocytes ratio (NLR; r = -0.181, p = 0.019). Multivariate analysis demonstrated that heart failure was the only significant predictor of 1-year mortality (OR 2.8, p = 0.002). LDL < 70 mg/dL at ACS hospitalization did not predict 1-year mortality in the HD group. Conclusions: Despite comparable lipid profiles and statin treatment before and after ACS hospitalization, mortality rates were significantly higher among HD group. While malnutrition-inflammation markers were associated with survival of dialysis patients after ACS, LDL cholesterol was not. Thus, our study results emphasize that better nutritional status and less inflammation are associated with improved survival among HD patients.

Renal Tubular CD24 Upregulation Aggravates Folic Acid Induced Acute Kidney Injury: A Possible Role for T Regulatory Cells Inhibition in Mice

Acute kidney injury (AKI) is characterized by cell death and inflammation. CD24 is a protein induced during tissue damage and is not expressed in mature renal tissue. We explored the role of CD24 in the pathogenesis of folic acid-induced AKI (FA-AKI) in mice. A single Intraperitoneal (IP) injection of folic acid induced AKI in WT and CD24^-/- mice. Renal function tests, histological analysis, immunohistochemistry, Western blot analysis, and ELISA were performed to assess the severity of renal damage and the intensity of the inflammatory response. FA-AKI induced CD24 in the distal tubular epithelial cells. Compared to WT mice, FA-AKI CD24^-/- mice exhibited an attenuated reduction in renal function and histological injury, lower serum IL-10 and interferon γ, and decreased expression of renal TNFα. In contrast, renal and systemic IL-33 upregulation were augmented. CD24^-/- FA-AKI animals exhibited increased splenic margination and renal infiltration of regulatory T cells (Tregs). At day 7, FA-AKI CD24^-/- mice exhibited increased expression of tubular pro-apoptotic and decreased anti-apoptotic proteins compared to WT animals. Anti-CD24 antibody administration to FA-AKI mice attenuated the decrease in renal function as well as the histological injury. Renal biopsies from patients with ATN stained strongly for CD24 in the distal tubules. In conclusion, during AKI, upregulation of CD24 promotes renal inflammation through inhibition of Treg infiltration and diversion of cell death towards necrosis rather than apoptosis. Neutralization of CD24 may prove a target for future therapies in AKI.

Acute Kidney Injury and Hair-Straightening Products: A Case Series

RATIONALE & OBJECTIVE

Keratin-based hair-straightening treatment is a popular hair-styling method. The majority of keratin-based hair-straightening products in Israel contain glycolic acid derivatives, which are considered safe when used topically. Systemic absorption of these products is possible, and anecdotal reports have described kidney toxicity associated with their use. We report a series of cases of severe acute kidney injury (AKI) following use of hair-straightening treatment in Israel during the past several years.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

We retrospectively identified 26 patients from 14 medical centers in Israel who experienced severe AKI and reported prior treatment with hair-straightening products in 2019-2022.

FINDINGS

The 26 patients described had a median age of 28.5 (range, 14-58) years and experienced severe AKI following a hair-straightening procedure. The most common symptoms at presentation were nausea, vomiting, and abdominal pain. Scalp rash was noted in 10 (38%) patients. Two patients experienced a recurrent episode of AKI following a repeat hair-straightening treatment. Seven patients underwent kidney biopsies, which demonstrated intratubular calcium oxalate deposition in 6 and microcalcification in tubular cells in 1. In all biopsies, signs of acute tubular injury were present, and an interstitial infiltrate was noted in 4 cases. Three patients required temporary dialysis.

LIMITATIONS

Retrospective uncontrolled study, small number of kidney biopsies.

CONCLUSIONS

This series describes cases of AKI with prior exposure to hair-straightening treatments. Acute oxalate nephropathy was the dominant finding on kidney biopsies, which may be related to absorption of glycolic acid derivatives and their metabolism to oxalate. This case series suggests a potential underrecognized cause of AKI in the young healthy population. Further studies are needed to confirm this association and to assess the extent of this phenomenon as well as its pathogenesis.

Predictors and Adverse Outcomes of Acute Kidney Injury in Hospitalized Renal Transplant Recipients

Data about in-hospital AKI in RTRs is lacking. We conducted a retrospective study of 292 RTRs, with 807 hospital admissions, to reveal predictors and outcomes of AKI during admission. In-hospital AKI developed in 149 patients (51%). AKI in a previous admission was associated with a more than twofold increased risk of AKI in subsequent admissions (OR 2.13, p &lt; 0.001). Other major significant predictors for in-hospital AKI included an infection as the major admission diagnosis (OR 2.93, p = 0.015), a medical history of hypertension (OR 1.91, p = 0.027), minimum systolic blood pressure (OR 0.98, p = 0.002), maximum tacrolimus trough level (OR 1.08, p = 0.005), hemoglobin level (OR 0.9, p = 0.016) and albumin level (OR 0.51, p = 0.025) during admission. Compared to admissions with no AKI, admissions with AKI were associated with longer length of stay (median time of 3.83 vs. 7.01 days, p &lt; 0.001). In-hospital AKI was associated with higher rates of mortality during admission, almost doubled odds for rehospitalization within 90 days from discharge and increased the risk of overall mortality in multivariable mixed effect models. In-hospital AKI is common and is associated with poor short- and long-term outcomes. Strategies to prevent AKI during admission in RTRs should be implemented to reduce re-admission rates and improve patient survival.

Nonalcoholic Fatty Liver Disease before Kidney Transplantation Correlates with New Onset Diabetes and Poor Metabolic Outcomes

INTRODUCTION

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality after kidney transplantation. Metabolic syndrome is common in renal transplant recipients and is associated with increased CVD risk in those patients. Nonalcoholic fatty liver disease (NAFLD) is considered to be the hepatic manifestation of a multi-system disorder, including CVD and metabolic syndrome. The data about prevalence of NAFLD before kidney transplantation and its consequences following transplantation are scarce.

METHODS

A retrospective study of metabolic parameters and sonographic evidence of NAFLD, and an analysis of its metabolic outcomes, was performed in 341 consecutive kidney transplant recipients.

RESULTS

One-hundred twenty-four (36.4%) kidney recipients had NAFLD before transplantation. The risk of NAFLD before kidney transplantation was independently and significantly related to diabetes (OR = 1.8), male gender (OR = 1.4), older age (every year of age increased the risk by 4%), higher BMI (every increase of 1 kg/m2 increased the risk by 15%), and higher triglycerides level. Mean levels of liver enzymes were similar in patients with and without NAFLD. Recipients with NAFLD before transplantation had a higher prevalence of new onset diabetes, even after adjustment to covariables. In addition, they had a higher increase in liver enzymes, triglycerides, and FIB-4 score, as an indication of liver fibrosis, after transplantation. Furthermore, NAFLD pre-transplantation was independently associated with cardiovascular mortality (HR = 4.4) following kidney transplantation.

CONCLUSIONS

Sonographic evidence of NAFLD before kidney transplantation is associated with significant metabolic outcomes including de novo diabetes and cardiovascular mortality following transplantation and should be included as part of the assessment of kidney transplant candidate.

Humoral Response and SARS-CoV-2 Infection Risk following the Third and Fourth Doses of the BNT162b2 Vaccine in Dialysis Patients

The optimal SARS-CoV-2 vaccination schedule in dialysis patients and the potential need for a fourth vaccine dose are debatable. We prospectively assessed the humoral responses to three and four doses of BNT162b2 among dialysis patients. The study included 106 dialysis patients; 60 (56.6%) and 46 (43.4%) received 3 and 4 vaccine doses, respectively. Anti-spike (anti-S) antibody titers significantly increased after the third vaccine dose, followed by a decline, yet still remained higher than all previous measurements. The fourth vaccine dose led to another profound rise in anti-S titers. The absolute increase following the fourth dose correlated with response to the third dose. Infection risk however was similar between patients vaccinated with three or four doses.

Humoral Response to the Third Dose of Sars-Cov-2 Vaccine in Kidney Transplant Recipients

BACKGROUND

Most solid organ transplant recipients did not develop an appreciable serologic response after 2 doses of the mRNA SARS-CoV-2 vaccine.

METHODS

We analyzed the humoral response after a third dose of the BNT162b2 vaccine in 130 kidney transplant recipients, compared to 48 health care workers, and associated factors, including prevaccine cellular immune response, by evaluating intracellular cytokine production after stimulation of donor's peripheral blood mononuclear cells.

RESULTS

After 2 doses, most of the controls (47 out of 48, 98%) and only 40% of kidney recipients (52 of 130) kidney recipients were seropositive (P < .001). Most seronegative recipients developed a serologic response after the booster (47 out 78, 60%), thus bringing the total number of seropositive recipients to 99 out of 130 (76%). After the third dose, there was a significant increase in antibodies titers in both groups. Decreased humoral response was significantly associated with an older age, lower lymphocyte count, and a lower level of antibodies before booster administration. CD4+TNFα+ and CD4+INFγ+ were correlated with mean increase in antibody titers.

CONCLUSIONS

A third dose of the BNT162b2 mRNA vaccine in kidney recipients is safe and effectively results in increased IgG anti-S levels, including in individuals who were seronegative after 2 doses. Long-term studies of the length of the immune response and protection are required.

Humoral response and breakthrough infections with SARS-CoV-2 B.1.617.2 variant in vaccinated maintenance hemodialysis patients

INTRODUCTION

Breakthrough COVID-19 may occur in vaccinated people, and may result from declining vaccine effectiveness or highly transmittable SARS-CoV-2 variants, such as the B.167.2 (delta) variant. We investigated risk factors and outcomes for infection with the delta variant among vaccinated hemodialysis patients.

METHODS

Patients on maintenance hemodialysis who received two doses of the BNT162b2 (Pfizer-BioNTech) vaccine were analysed according to having developed COVID-19 (study group) or not (control group), in a retrospective, observational, comparative study. We compared risk-factors for developing breakthrough COVID-19 and assessed clinical outcomes, including 30-day mortality rates.

RESULTS

Twenty-four cases of breakthrough SARS-CoV-2 infection were compared to 91 controls without infection. Breakthrough infection was associated with chronic immunosuppressive treatment, hematological malignancies, and low antibody levels against SARS-CoV-2 spike protein. All COVID-19 cases occurred at least 5 months after vaccination, and most were caused by the B.1.617.2 variant (at least 23/24 cases). COVID-19 was categorized as severe or critical disease in 11/24 patients (46%), and 54% required hospitalization and COVID-19-directed treatment. The source of infection was nosocomial in 6/24 cases (25%), and healthcare-related in 3/24 (12.5%). Mortality rate was 21%. Overall mortality was significantly higher in patients who developed COVID-19 than in controls (odds ratio for all-cause mortality 7.6, 95% CI 1.4-41, p = 0.002).

CONCLUSIONS

Breakthrough COVID-19 with the B.1.617.2 variant can occur in vaccinated hemodialysis patients and is associated with immunosuppression and weaker humoral response to vaccination. Infections may be nosocomial and result in significant morbidity and mortality.

Presence of Sarcopenia before Kidney Transplantation Is Associated with Poor Outcomes

Introduction

Kidney transplantation is the treatment of choice for patients with renal failure. It is crucial to select which patients may benefit from renal transplantation and which are at high risk for post-transplant complications. Sarcopenia is associated with poor outcome in various conditions, including in chronic kidney disease patients. The gold standard for measuring sarcopenia is computed tomography (CT) imaging to estimate muscle mass and quality since it is objective, reproducible, and reflects the overall health condition. The data regarding those measurements among kidney transplant recipients are limited, therefore we aimed to describe it in patients before kidney transplantation, assess the parameters associated with sarcopenia, and evaluate the clinical significance of those markers on outcomes following transplantation.

Methods

We retrospectively analyzed 183 kidney transplant recipients who had a CT scan 90 days prior to transplant. Sarcopenia was assessed by measuring the cross-sectional area (CSA) and mean muscle density of the psoas muscle at the third and fourth lumbar vertebrae levels and paravertebral muscles at the 12th thoracic vertebra level.

Results

There was a strong linear correlation between muscle size measured as CSA of the psoas muscle at the L3 and L4 vertebral body level and the CSA of the paravertebral muscles at the D12 vertebra level, and a moderate correlation to muscle density at those levels. Age was independently associated with risk of sarcopenia, defined as psoas CSA in the lowest tertile, with every year of age increasing the risk by 5%. CSA at the L3 level had a significant independent association with post kidney transplantation mortality, with an adjusted hazard ratio of 0.86 per cm². There was a significantly longer hospitalization period postoperation in kidney recipients in the lower tertile of psoas CSA and density.

Conclusions

Sarcopenia as measured by psoas CSA is associated with poor short- and long-term outcomes following kidney transplantation and should be included as part of the assessment of kidney transplantation candidates.

MO276: Renal Tubular CD24 Upregulation Aggravates Folic Acid-Induced Acute Kidney Injury Through Inhibition of Regulatory T Cells in Mice

BACKGROUND AND AIMS

Acute kidney injury (AKI) is characterized by cell death and inflammation. CD24 is a sialoglycoprotein which is induced during tissue damage and is not expressed in matured renal tissue. We explored the role of CD24 in the pathogenesis of folic acid-induced AKI (FA-AKI) in mice.

METHOD

A single i.p. injection of folic acid induced AKI in WT and CD24-/- mice. Renal function tests, histological analysis, immunohistochemistry, Western blot analysis and ELISA were performed to assess the severity of renal damage and the intensity of the inflammatory response.

RESULTS

FA-AKI induced the expression of CD24 in the distal tubular epithelial cells. Compared to WT mice, FA-AKI CD24-/- mice exhibited an attenuated reduction in renal function and histological injury, lower serum IL-10 and interferon γ, and decreased expression of renal TNFα. Renal and systemic IL-33 were upregulated in both groups. However, it was more pronounced in FA-AKI CD24-/- animals. FA-AKI CD24-animals exhibited increased splenic margination and renal infiltration of regulatory T cells (Tregs). At day 7, FA-AKI CD24-/- mice demonstrated increased expression of tubular pro-apoptotic (activated caspase 3) and decreased anti-apoptotic (Bcl-xL) proteins compared with WT animals. Administration of anti CD24 antibody to FA-AKI mice attenuated the decrease in renal function and ameliorated the histological injury in comparison with untreated animals.

Renal biopsies from patients with ATN stained strongly for CD24 in the distal tubules.

CONCLUSION

During AKI, upregulation of CD24 promotes renal inflammation through inhibition of Tregs infiltration and diversion of cell death towards necrosis rather than apoptosis. Neutralization of CD24 may prove as a target for future therapies in AKI.

MO887: Humoral Response to the Pfizer BNT162b2 Vaccine Booster Dose in Patients Undergoing Maintenance Hemodialysis

BACKGROUND AND AIMS

COVID-19 is associated with increased morbidity and mortality in maintenance hemodialysis (MHD) patients. Recent breakthrough infection in vaccinated people has led some authorities to recommend a booster dose to patient fully vaccinated 5–8 months ago. The recent emergence of the Omicron (B.1.1.529) variant has heightened this issue.

We aimed to assess, the humoral response following a booster dose with the BNT162b2 vaccine in MHD patients.

METHOD

The study included 102 MHD patients vaccinated with 2 doses of the BNT162b2 (Pfizer-BioNTech) vaccine. A third dose (booster) was recommended to all MHD Patients in our center and was given to all patients that opt to receive it, resulting in a booster group and a control group that did not receive the booster. Previous exposure was excluded by testing for the presence of the Anti-Nucleocapsid Antibody (SARS-CoV-2) or positive PCR. We assessed the humoral response before and after the booster dose.

RESULTS

98.5% (65/66) subjects in the booster group developed a positive antibody response (472.7 ± 749.5 to 16 336.8 ± 15 397.3 AU/mL) as compared with a sustained decrease in the control group (n = 22, 695.7 ± 642.7 to 383.6 ± 298.6 AU/mL), P &lt; 0.0001 (Figure 1). No significant adverse effects were reported. Prior antibody titers were positively correlated to IgG S1 levels following the booster dose. There was a significant association between malnutrition-inflammation markers and the humoral response.

CONCLUSION

The vast majority of MHD patients developed a substantial humoral response following the booster dose administration, it was significantly higher than levels previously reported for MHD patients following administration of 2 doses alone. Further studies and observations are needed in order to determine the exact timing and dosing schedule.

MO822: Humoral Response and Breakthrough Infections With SARS-COV-2 B.1.617.2 Variant in Vaccinated Maintenance Hemodialysis Patients

BACKGROUND AND AIMS

Breakthrough COVID-19 may occur in vaccinated people and may result from declining vaccine effectiveness or highly transmittable SARS-CoV-2 variants, such as the B.167.2 (delta) variant. The recent emergence of the Omicron (B.1.1.529) variant has heightened this issue.

We investigated risk factors and outcomes for infection with the delta variant among vaccinated hemodialysis patients.

METHOD

Patients on maintenance hemodialysis who received two doses of the BNT162b2 (Pfizer-BioNTech) vaccine were categorized into the study group who developed COVID-19 and controls who did not in retrospective, observational and comparative study.

We compared risk factors for developing COVID-19 between two study groups and assessed clinical outcomes, including 30-day mortality rates.

RESULTS

A total of 25 cases of breakthrough SARS-CoV-2 infection were compared with 91 controls without. Breakthrough infection was associated with chronic immunosuppressive treatment, hematological malignancies and low antibody levels against SARS-CoV-2 spike protein (P = 0.001, 0.006 and 0.4, respectively). All COVID-19 cases occurred at least 5-months after vaccination and were caused by the B.1.617.2 variant in at least 23/25 cases. COVID-19 was categorized as severe or critical disease in 11/25 patients (44%) and 52% required hospitalization and COVID-19-directed treatment. The source of infection was nosocomial in 6/25 cases (24%), and healthcare-related in additional 3/25 (12%). Mortality rate was 20%, and overall mortality was significantly higher in subjects who developed COVID-19 than in controls (odds ratio for all-cause mortality 7.3, 95% confidence interval 1.6–33.2; P = 0.004).

CONCLUSION

Breakthrough COVID-19 with the B.1.617.2 variant can occur in vaccinated hemodialysis patients and is associated with immunosuppression and a weaker vaccine immune response. Infections may be nosocomial and result in significant morbidity and mortality.

Humoral Response to Pfizer BNT162b2 Vaccine Booster in Maintenance Hemodialysis Patients

INTRODUCTION

Coronavirus disease is associated with increased morbidity and mortality in maintenance hemodialysis (MHD) patients. Recent breakthrough infection in vaccinated people has led some authorities to recommend a booster dose for patients fully vaccinated 5-8 months ago. We aimed to assess the humoral response of MHD patients following a booster dose with the BNT162b2 vaccine.

METHODS

The study included 102 MHD patients vaccinated with 2 doses of the BNT162b2 (Pfizer-BioNTech) vaccine. A third dose (booster) was recommended to all MHD patients in our center and was given to those who opted to receive it, resulting in a booster group and a control group that did not receive the booster. Previous exposure was excluded by testing for the presence of the anti-nucleocapsid antibody (SARS-CoV-2) or positive PCR. We assessed the humoral response before and after the booster dose.

RESULTS

Of 66 patients in the booster group, 65 patients (98.5%) developed a positive antibody response, from 472.7 ± 749.5 to 16,336.8 ± 15,397.3, as compared to a sustained decrease in the control group (695.7 ± 642.7 to 383.6 ± 298.6), p < 0.0001. No significant adverse effects were reported. Prior antibody titers were positively correlated to IgG levels following the booster dose. There was a significant association between malnutrition-inflammation markers and the humoral response.

CONCLUSIONS

Almost all MHD patients developed a substantial humoral response following the booster dose, which was significantly higher than levels reported for MHD patients following administration of 2 doses alone. Further studies and observations are needed to determine the exact timing and dosing schedule.

Kidney transplant recipients vaccinated before transplantation maintain superior humoral response to SARS-CoV-2 vaccine

Majority of transplant recipients did not develop an appreciable humoral response following SARS-CoV-2 vaccine, in contrast to dialysis patients and healthy individuals. We analyzed the serologic response to BNT162b2 (Pfizer-BioNTech) vaccine in a cohort of 19 kidney transplant recipients, vaccinated prior to transplantation, compare to 109 recipients vaccinated after transplantation, and to 39 healthcare workers, by determining the level of anti-spike antibodies after transplantation. All controls and 17 of 19 (90%) of recipients vaccinated before transplant were seropositive, while only 49 of 109 (45%) recipients vaccinated post-transplant had positive serology (P < .001). Median anti-spike IgG in the group of kidney transplant recipients vaccinated after transplantation (10.7 AU/ml, [IQR 0-62.5]) was lower than the patients vaccinated before transplantation (66.2 AU/ml [21.6-138]), which was significantly lower than in the controls (156 AU/ml [99.7-215.5]). Negative humoral response was associated with vaccination post transplantation (odds ratio 22.4), older age (OR = 1.04), and longer time on dialysis (OR = 1.02), while higher lymphocyte count at time of vaccination was protective (OR = .52). Our findings of sustained superior humoral response to SARS-CoV-2 vaccine in kidney transplant recipients vaccinated prior to transplantation strongly support the recommendations of SARS-CoV-2 vaccination of transplant candidates, especially those younger than 60 years.

Occurrence of BNT162b2 Vaccine Adverse Reactions Is Associated with Enhanced SARS-CoV-2 IgG Antibody Response

Promoting SARS-CoV-2 vaccination has been a global mission since the first vaccines were approved for emergency use. Alongside the excitement following the possibility of eradicating SARS-CoV-2 and ending the COVID-19 pandemic, there has been ample vaccine hesitancy, some due to the abundant reporting of adverse reactions. We report here that the occurrence of BNT162b2 vaccine adverse reactions is associated with enhanced antibody response. We found a statistically significant correlation between having an adverse reaction, whether local or systemic, and higher antibody levels. No sex difference was observed in antibody levels. However, as was recently reported, the antibody response was found to be lower among older vaccinees. The demonstration of a clear correlation between adverse reactions and antibody levels may help reduce vaccination hesitancy by reassuring that the presence of such reactions is an indication of a well-functioning immune system.

Reduced humoral response to mRNA SARS-CoV-2 BNT162b2 vaccine in kidney transplant recipients without prior exposure to the virus

COVID-19 is associated with increased morbidity and mortality in transplant recipients. There are no efficacy data available regarding these patients with any of the available SARS-CoV-2 vaccines. We analyzed the humoral response following full vaccination with the BNT162b2 (Pfizer-BioNTech) in 136 kidney transplant recipients, and compared it to 25 controls. In order to exclude prior exposure to the virus, only participants with negative serology to SARS-CoV-2 nucleocapsid protein were included. All controls developed a positive response to spike protein, while only 51 of 136 transplant recipients (37.5%) had positive serology (p < .001). Mean IgG anti-spike level was higher in the controls (31.05 [41.8] vs. 200.5 [65.1] AU/mL, study vs. control, respectively, p < .001). Variables associated with null humoral response were older age (odds ratio 1.66 [95% confidence interval 1.17-2.69]), high-dose corticosteroids in the last 12 months (1.3 [1.09-1.86]), maintenance with triple immunosuppression (1.43 [1.06-2.15]), and regimen that includes mycophenolate (1.47 [1.26-2.27]). There was a similar rate of side effects between controls and recipients, and no correlation was found between the presence of symptoms and seroconversion. Our findings suggest that most kidney transplant recipients remain at high risk for COVID-19 despite vaccination. Further studies regarding possible measures to increase recipient's response to vaccination are required.

Humoral Response to the Pfizer BNT162b2 Vaccine in Patients Undergoing Maintenance Hemodialysis

BACKGROUND AND OBJECTIVES

Coronavirus disease 2019 (COVID-19) is associated with higher morbidity and mortality in patients on maintenance hemodialysis. Patients on dialysis tend to have a reduced immune response to infection or vaccination. We aimed to assess, for the first time to the best of our knowledge, the humoral response following vaccination with the BNT162b2 vaccine in patients on maintenance hemodialysis and the factors associated with it.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The study included 56 patients on maintenance hemodialysis (dialysis group) and a control group composed of 95 health care workers. All participants had received two doses of the BNT162b2 (Pfizer-BioNTech) vaccine. The serology testing was done using Quant II IgG anti-Spike severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) assay by Abbott a median of 30 days after receipt of the second dose of the vaccine.

RESULTS

All subjects in the control group developed an antibody response compared with 96% (54 of 56) positive responders in the dialysis group. The IgG levels in the dialysis group (median, 2900; interquartile range, 1128-5651) were significantly lower than in the control group (median, 7401; interquartile range, 3687-15,471). A Mann-Whitney U test indicated that this difference was statistically significant (U=1238; P<0.001). There was a significant inverse correlation of age and IgG levels in both groups. The odds of being in the lower quartile were significantly higher for older individuals (odds ratio, 1.11 per year of age; 95% confidence interval, 1.08 to 1.20; P=0.004) and for the dialysis group compared with the control group (odds ratio, 2.7; 95% confidence interval, 1.13 to 7.51; P=0.05). Within the dialysis group, older age and lower lymphocyte count were associated with antibody response in the lower quartile (odds ratio, 1.22 per 1-year older; 95% confidence interval, 1.13 to 1.68; P=0.03 and odds ratio, 0.83 per 10-e3/µl-higher lymphocyte count; 95% confidence interval, 0.58 to 0.97; P=0.05).

CONCLUSIONS

Although most patients on maintenance hemodialysis developed a substantial humoral response following the BNT162b2 vaccine, it was significantly lower than controls. Age was an important factor in the humoral response, regardless of chronic medical conditions.

Profound Decrease in Glomerular Arginine Transport by CAT (Cationic Amino Acid Transporter)-1 Contributes to the FLT-1 (FMS-Like Tyrosine Kinase 1) Induced Preeclampsia in the Pregnant Mice

Endothelial dysfunction because of nitric oxide inactivation has been suggested to play a role in the pathogenesis of preeclampsia. During pregnancy, L-arginine transport by CAT-1 (cationic amino acid transporter 1), the only transporter for eNOS (endothelial nitric oxide synthase) is inhibited. We hypothesize that maternal arginine deficiency contributes to the development of preeclampsia. Adenovirus-mediated overexpression of sFlt-1 (soluble fms-like tyrosine kinase 1) in virgin and pregnant mice resulted in glomerular endotheliosis, hypertension, and albuminuria. L-arginine prevented the increase in blood pressure and albuminuria in Flt-1 pregnant but not in Flt-1 virgin mice. Flt-1 augmented arginine transport in pregnant but not in virgin dames. Ex vivo inhibition of CAT-2 leaving exclusively CAT-1 activity, decreased arginine transport velocities in Flt-1 animals more prominently in pregnant dames. Phosphorylated CAT-1/CAT-1 increased in pregnant, sFlt-1-pregnant, and sFlt-1 virgin mice. CAT-2 increased in Flt-1-pregnant and Flt-1-virgin dames. L-arginine augmented arginine transport in pregnant and Flt-pregnant mice and prevented the increase in pCAT-1 and CAT-2 expression. Glomerular cGMP (cyclic guanosine monophosphate) generation as a measure of eNOS activity was decreased in all Flt-1 treated animals. L-arginine abolished the decrease in cGMP levels only in Flt-1-pregnant mice. In conclusion, glomerular endothelial NO generation is compromised in Flt-1-pregnant mice because of CAT-1 inhibition induced by a combined effect of pregnancy and preeclampsia which involves: phosphorylation of CAT-1 and induction of CAT-2. These processes contribute to the clinical syndrome of preeclampsia in mice and are prevented by L-arginine.

Hypertension is associated with increased post-exercise albuminuria, which may be attenuated by an active lifestyle

Albuminuria is a known marker for endothelial dysfunction and cardiovascular events, even below the threshold of moderately increased albuminuria (MIA). Post-exercise increased albuminuria may precede the appearance of rest MIA, enabling detection of early injury. Modifying lifestyle for a population at risk for MIA is therefore of interest. Our aim was to evaluate post-exercise albuminuria in hypertensive compared with normotensive individuals and to analyze the effect of an active lifestyle on rest and post-exercise albumin excretion. The study cohort consisted of 3931 adults who participated in a health-screening program. Albuminuria was measured as urine albumin-to-creatinine ratio (ACR). Lifestyle was divided into three groups: non-active, less-active, and active according to regular sport activity, categorized as follows: none, <2.5 and ≥2.5 hours per week. Mean age was 47.7 years, and 31.2% (n = 1228) were diagnosed with hypertension. Both rest and post-exercise ACR were higher in hypertensive compared to normotensive participants. Rest ACR was higher in non-active compared to less-active and active hypertensive participants. Hypertensive participants with an active lifestyle had significantly lower post-exercise and delta ACR compared to less-active and non-active hypertensive participants. Parameters related to delta ACR in hypertensive participants were increased age, BMI, and diabetes, while active lifestyle and fitness (measured as METS achieved by a stress test) were protective. In conclusion, there is an association between hypertension and increased albumin excretion post-exercise, which can be attenuated with an active lifestyle.

Kidney transplantation in patients with inflammatory bowel diseases (IBD): analysis of transplantation outcome and IBD activity

Inflammatory bowel diseases (IBD) is a systemic disorder with possible renal involvement, yet data regarding the outcome of kidney transplantation (KT) in those patients, and IBD course post KT, are scarce. In this retrospective analysis, we studied the outcome of 12 IBD kidney recipients (seven Crohn's disease, five ulcerative colitis; primary kidney disease was IgA nephropathy in five, polycystic disease in four), compared to two control groups: matched controls and a cohort of recipients with similar kidney disease. During a follow-up period of 60.1 (11.0-76.6) months (median, interquartile range), estimated 5-year survival was 80.8 vs. 96.8%, with and without IBD, respectively (P = 0.001). Risk of death with a functioning graft was higher with IBD (HR = 1.441, P = 0.048), and with increased age (HR = 1.109, P = 0.05). Late rehospitalization rate was higher in IBD [incidence rate ratio = 1.168, P = 0.030], as well as rate of hospitalization related to infection [1.42, P = 0.037]. All patients that were in remission before KT, remission was maintained. Patients that were transplanted with mild or moderate disease remained stable or improved with Infliximab or Adalimumab treatment. In conclusion, IBD is associated with an increased risk of mortality, hospitalization because of infection and late rehospitalization after KT. Clinical course of IBD is stable after KT.

Long term metabolic and renal outcomes of kidney donors compared to controls with excellent kidney function

Background

Only few studies of living kidney donors have included controls that were similarly healthy, including excellent kidney function.

Methods

In this study, we aimed to estimate long term metabolic and renal outcome in a cohort of 211 living donors compared to two control groups: paired-matched controls, and another control group of 2534 healthy individuals with excellent kidney function.

Results

Donors presented with higher estimated Glomerular Filtration Rate (eGFR): (97.6 ± 15.2 vs 96.1 ± 12.2 vs 94.5 ± 12.4 ml/min/1.73m²) and lower urine albumin to creatinine ratio (UACR) (4.3 ± 5.9 vs 5.9 ± 6.1 vs 6.1 ± 6.9 mg/g) for donors, matched controls and healthy controls, respectively (p <  0.001). In a mean follow up period of 5.5 for donors, donors presented with positive eGFR slopes during the first 3 years post donation, followed by negative slopes, compared to constantly negative slopes presented in the control group (p <  0.05). The variables related to the slope were being a donor, baseline eGFR, Body Mass Index (BMI) and age but not eGFR on the last day of follow-up or increased delta UACR. There was a significant increase in UACR in donors, as well as a higher rate of albuminuria, associated with a longer time since donation, higher pre-donation UACR and higher pre-donation BMI. Healthy controls had a lower BMI at baseline and gained less weight during the follow up period. Donors and controls had similar incidence of new onset diabetes mellitus and hypertension, as well as similar delta systolic and diastolic blood pressure. Donors were more likely to develop new onset metabolic syndrome, even after adjustment for age, gender and BMI. The higher incidence of metabolic syndrome resulted mainly from increased triglycerides and impaired fasting glucose criteria. However, prevalence of major cardiovascular events was not higher in this group.

Conclusions

Donors are at increased risk to develop features of the metabolic syndrome in addition to the expected mild reduction of GFR and increased urine albumin excretion. Future studies are needed to explore whether addressing those issues will impact post donation morbidity and mortality.

Ultrapure Filter does not Confer Short-Term Benefits over Two Reverse Osmosis Systems in Chronic Hemodialysis Patients

BACKGROUND

Dialysate purity contributes to the inflammatory response that afflicts hemodialysis patients.

OBJECTIVES

To compare the clinical and laboratory effects of using ultrapure water produced by a water treatment system including two reverse osmosis (RO) units in series, with a system that also includes an ultrapure filter (UPF).

METHODS

We performed a retrospective study in 193 hemodialysis patients during two periods: period A (no UPF, 6 months) and period B (same patients, with addition of UPF, 18 months), and a historical cohort of patients treated in the same dialysis unit 2 years earlier, which served as a control group.

RESULTS

Mean C-reactive protein, serum albumin and systolic blood pressure worsened in period B compared to period A and in the controls.

CONCLUSIONS

A double RO system to produce ultrapure water is not inferior to the use of ultrapure filters.

Mineralocorticoid receptor blockade improves arginine transport and nitric oxide generation through modulation of cationic amino acid transporter-1 in endothelial cells

Blockade of the mineralocorticoid receptor (MCR) has been shown to improve endothelial function far beyond blood pressure control. In the current studies we have looked at the effect of MCR antagonists on cationic amino acid transporter-1 (CAT-1), a major modulator of endothelial nitric oxide (NO) generation. Using radio-labeled arginine, {[³H] l-arginine} uptake was determined in human umbilical vein endothelial cells (HUVEC) following incubation with either spironolactone or eplerenone with or without silencing of MCR. Western blotting for CAT-1, PKCα and their phosphorylated forms were performed. NO generation was measured by using Griess reaction assay. Both Spironolactone and eplerenone significantly increased endothelial arginine transport, an effect which was further augmented by co-incubation with aldosterone, and blunted by either silencing of MCR or co-administration of amiloride. Following MCR blockade, we identified two bands for CAT-1. The addition of tunicamycin (an inhibitor of protein glycosylation) or MCR silencing resulted in disappearance of the extra band and prevented the increase in arginine transport. Only spironolactone decreased CAT-1 phosphorylation through inhibition of PKCα (CAT-1 inhibitor). Subsequently, incubation with either MCR antagonists significantly augmented NO2/NO3 levels (stable NO metabolites) and this was attenuated by silencing of MCR or tunicamycin. GO 6076 (PKCα inhibitor) intensified the increase of NO metabolites only in eplerenone treated cells. In conclusion spironolactone and eplerenone augment arginine transport and NO generation through modulation of CAT-1 in endothelial cells. Both MCR antagonists activate CAT-1 by inducing its glycosylation while only spironolactone inhibits PKCα.

Normal-range albuminuria in healthy subjects increases over time in association with hypertension and metabolic outcomes

Albuminuria is a prognostic factor for mortality and cardiovascular events, even at low levels. Changes in albumin excretion are associated with end-stage renal disease and hypertension (HTN) in cohorts including high-risk participants. We aimed to investigate the evolvement of albumin excretion in healthy individuals with normal kidney function and normoalbuminuria, and possible associations with HTN and metabolic outcomes. The study cohort consisted of 1967 healthy adults with normal kidney function (estimated glomerular filtration rate ≥ 90 mL/min/1.73 m²; urine albumin to creatinine ratio [ACR] < 30 mg/g). Delta ACR slope was calculated as ACR difference between two consecutive visits divided by the time interval. During a mean follow-up period of 93.8 months, mean delta ACR slope was 0.27 ± 3.29 mg/g/year and was higher in participants with age >40 years, obesity, a high waist circumference, higher baseline ACR, HTN, prediabetes, and metabolic syndrome. Delta ACR slopes in the upper quartile predicted diabetes (OR = 1.31, P = .027) and albuminuria (4.34, P < .001). Upper quartile of ACR slopes correlated with a higher risk for new-onset HTN (1.249, P = .031). Delta systolic and diastolic blood pressures were associated with ACR slopes in addition to age, body mass index, and baseline ACR. In conclusion, accelerated change in ACR correlates with HTN and diabetes in healthy individuals with normal kidney function and normoalbuminuria.

Uremic Solute-Aryl Hydrocarbon Receptor-Tissue Factor Axis Associates with Thrombosis after Vascular Injury in Humans

Individuals with CKD are particularly predisposed to thrombosis after vascular injury. Using mouse models, we recently described indoxyl sulfate, a tryptophan metabolite retained in CKD and an activator of tissue factor (TF) through aryl hydrocarbon receptor (AHR) signaling, as an inducer of thrombosis across the CKD spectrum. However, the translation of findings from animal models to humans is often challenging. Here, we investigated the uremic solute-AHR-TF thrombosis axis in two human cohorts, using a targeted metabolomics approach to probe a set of tryptophan products and high-throughput assays to measure AHR and TF activity. Analysis of baseline serum samples was performed from 473 participants with advanced CKD from the Dialysis Access Consortium Clopidogrel Prevention of Early AV Fistula Thrombosis trial. Participants with subsequent arteriovenous thrombosis had significantly higher levels of indoxyl sulfate and kynurenine, another uremic solute, and greater activity of AHR and TF, than those without thrombosis. Pattern recognition analysis using the components of the thrombosis axis facilitated clustering of the thrombotic and nonthrombotic groups. We further validated these findings using 377 baseline samples from participants in the Thrombolysis in Myocardial Infarction II trial, many of whom had CKD stage 2-3. Mechanistic probing revealed that kynurenine enhances thrombosis after vascular injury in an animal model and regulates thrombosis in an AHR-dependent manner. This human validation of the solute-AHR-TF axis supports further studies probing its utility in risk stratification of patients with CKD and exploring its role in other diseases with heightened risk of thrombosis.

Targeting STUB1-tissue factor axis normalizes hyperthrombotic uremic phenotype without increasing bleeding risk

Chronic kidney disease (CKD/uremia) remains vexing because it increases the risk of atherothrombosis and is also associated with bleeding complications on standard antithrombotic/antiplatelet therapies. Although the associations of indolic uremic solutes and vascular wall proteins [such as tissue factor (TF) and aryl hydrocarbon receptor (AHR)] are being defined, the specific mechanisms that drive the thrombotic and bleeding risks are not fully understood. We now present an indolic solute-specific animal model, which focuses on solute-protein interactions and shows that indolic solutes mediate the hyperthrombotic phenotype across all CKD stages in an AHR- and TF-dependent manner. We further demonstrate that AHR regulates TF through STIP1 homology and U-box-containing protein 1 (STUB1). As a ubiquitin ligase, STUB1 dynamically interacts with and degrades TF through ubiquitination in the uremic milieu. TF regulation by STUB1 is supported in humans by an inverse relationship of STUB1 and TF expression and reduced STUB1-TF interaction in uremic vessels. Genetic or pharmacological manipulation of STUB1 in vascular smooth muscle cells inhibited thrombosis in flow loops. STUB1 perturbations reverted the uremic hyperthrombotic phenotype without prolonging the bleeding time, in contrast to heparin, the standard-of-care antithrombotic in CKD patients. Our work refines the thrombosis axis (STUB1 is a mediator of indolic solute-AHR-TF axis) and expands the understanding of the interconnected relationships driving the fragile thrombotic state in CKD. It also establishes a means of minimizing the uremic hyperthrombotic phenotype without altering the hemostatic balance, a long-sought-after combination in CKD patients.

Vascular Endothelial Growth Factor Augments Arginine Transport and Nitric Oxide Generation via a KDR Receptor Signaling Pathway

BACKGROUND/AIMS

Vascular endothelial growth factor (VEGF) is an endothelium-specific peptide that stimulates angiogenesis via two receptor tyrosine kinases, Flt-1 and KDR. Endothelial nitric oxide synthase (eNOS) plays a major role in VEGF signaling. Delivery of arginine to membrane bound eNOS by the cationic amino acid transporter-1 (CAT-1) has been shown to modulate eNOS activity. The current studies were designed to test the hypothesis that VEGF enhances eNOS activity via modulation of arginine transport by CAT-1.

METHODS

Using radio-labeled arginine, {[3H] L-arginine} uptake was determined in human umbilical vein endothelial cells (HUVEC) following incubation with VEGF with and without silencing the VEGF receptors Flt-1 or KDR. Subsequently, western blotting for CAT-1, PKCα, ERK 1/2, JNK, and their phosphorylated forms were performed. NO generation was measured by the Griess reaction.

RESULTS

VEGF (50 and 100 ng/ml) significantly augmented endothelial arginine transport in a time dependent manner, an effect which was prevented by Sunitinib (2 µM), a multi targeted receptor tyrosine kinase inhibitor. The increase in arginine transport velocities by VEGF was not affected by silencing Flt-1 while silencing KDR abrogated VEGF effect. Furthermore, incubating cells with 50 and 100 ng of VEGF for 30 minutes significantly augmented CAT-1 abundance. The expression of PKC-α, JNK, and ERK1/2 and their phosphorylated forms were unchanged following incubation of HUVEC with VEGF. The concentration of NO2/NO3 following incubation with VEGF was significantly higher than from untreated cells. This increase was significantly attenuated by silencing KDR.

CONCLUSIONS

VEGF increases arginine transport via modulation of CAT-1 in endothelial cells. This effect is exclusively dependent on KDR rather than Flt-1.

Target Hemoglobin May Be Achieved with Intravenous Iron Alone in Anemic Patients with Cardiorenal Syndrome: An Observational Study

BACKGROUND

The treatment of anemia in patients with cardiorenal syndrome (CRS) is based mainly on intravenous (IV) iron therapy and/or erythropoiesis-stimulating agents (ESAs). There are concerns about the safety of ESAs due to a potentially higher risk for stroke and malignancy.

OBJECTIVE

We aimed to explore whether IV iron alone is sufficient to improve anemia in CRS patients and to define the predictors of treatment response.

METHODS

We retrospectively analyzed data of 81 CRS patient treated for anemia at our clinic. All patients received IV iron for 6 weeks. A subset of patients was additionally given subcutaneous ESAs. The end point was the improvement from baseline in hemoglobin (Hb) and ferritin levels at week 7.

RESULTS

We retrieved the files of 81 patients; 34 received IV iron alone and 47 were given IV iron and ESAs (the combination group). The Hb levels significantly increased in both groups (in the IV iron alone group: 10.6 ± 1.1 to 11.9 ±1.1 g/dl, p < 0.001; in the combination group: 10.2 ± 0.9 to 12.4 ± 1.3 g/dl, p < 0.001), but more pronouncedly in the combination group (2.17 vs. 1.24 g/dl; p = 0.001). The platelet count decreased significantly in the IV iron alone group but was unchanged in the combination group. Eighty percent of patients attained a Hb target of 11 g/dl, with no significant difference between the two groups (73.5 vs. 85.1%; p = 0.197). Low baseline Hb was the only predictor of a favorable outcome to treatment.

CONCLUSION

Our observational study suggests that IV iron treatment without ESAs may substantially raise the Hb level to ≥11 g/dl in CRS patients. This treatment strategy may reduce the use of ESAs and hence its potential adverse effects.

The Aryl Hydrocarbon Receptor is a Critical Regulator of Tissue Factor Stability and an Antithrombotic Target in Uremia

Patients with CKD suffer high rates of thrombosis, particularly after endovascular interventions, yet few options are available to improve management and reduce thrombotic risk. We recently demonstrated that indoxyl sulfate (IS) is a potent CKD-specific prothrombotic metabolite that induces tissue factor (TF) in vascular smooth muscle cells (vSMCs), although the precise mechanism and treatment implications remain unclear. Because IS is an agonist of the aryl hydrocarbon receptor (AHR), we first examined the relationship between IS levels and AHR-inducing activity in sera of patients with ESRD. IS levels correlated significantly with both vSMC AHR activity and TF activity. Mechanistically, we demonstrated that IS activates the AHR pathway in primary human aortic vSMCs, and further, that AHR interacts directly with and stabilizes functional TF. Antagonists directly targeting AHR enhanced TF ubiquitination and degradation and suppressed thrombosis in a postinterventional model of CKD and endovascular injury. Furthermore, AHR antagonists inhibited TF in a manner dependent on circulating IS levels. In conclusion, we demonstrated that IS regulates TF stability through AHR signaling and uncovered AHR as an antithrombotic target and AHR antagonists as a novel class of antithrombotics. Together, IS and AHR have potential as uremia-specific biomarkers and targets that may be leveraged as a promising theranostic platform to better manage the elevated thrombosis rates in patients with CKD.

The c-Cbl ubiquitin ligase regulates nuclear β-catenin and angiogenesis by its tyrosine phosphorylation mediated through the Wnt signaling pathway

Wnt signaling plays important roles in both the tumor-induced angiogenesis and tumorigenesis through the transcriptionally active nuclear β-catenin. Recently, c-Cbl was identified as a unique E3 ubiquitin ligase targeting the active nuclear β-catenin. However, little is known about the molecular mechanisms by which c-Cbl regulates ubiquitination and degradation of active β-catenin. Here, we demonstrate that Wnt activation promotes the phosphorylation of c-Cbl at tyrosine 731(Tyr-731), which increases c-Cbl dimerization and binding to β-catenin. Tyr-731 phosphorylation and dimerization mediate c-Cbl nuclear translocation and lead to the degradation of nuclearly active β-catenin in the Wnt-on phase. c-Cbl activation also inhibits expression of the pro-angiogenic Wnt targets, IL-8 and VEGF. Phospho-Tyr-731-inactive mutant c-Cbl (Y731F) enhances and phosphomimetic mutant c-Cbl (Y731E) suppresses angiogenesis in zebrafish. Taken together, we have identified a novel mechanism for the regulation of active nuclear β-catenin by c-Cbl and its critical role in angiogenesis. This mechanism can be further explored to modulate both the pathological angiogenesis and the tumorigenesis.

Cyclosporine attenuates arginine transport, in human endothelial cells, through modulation of cationic amino acid transporter-1

BACKGROUND

The spectrum of cardiovascular toxicity by cyclosporine (CsA) includes hypertension, accelerated atherosclerosis, and thrombotic microangiopathy, all of which are the result of endothelial cell dysfunction. Endothelial cell dysfunction is characterized by decreased endothelial nitric oxide synthase (eNOS) activity. Cationic amino acid transporter-1 (CAT-1) is the specific arginine transporter for eNOS. CsA has been shown to attenuate nitric oxide (NO) generation. However, the mechanism remains elusive. We hypothesize that CsA inhibits eNOS activity through modulation of its selective arginine supplier CAT-1.

METHODS

We studied the effect of CsA on arginine uptake, NO2/NO3 generation, and CAT-1, protein kinase Cα (PKCα), and phosphorylated PKCα protein expression in human umbilical vein endothelial cell cultures (HUVEC) in the absence and presence of L-arginine.

RESULTS

CsA (0.5-2 μg/ml) significantly attenuated arginine transport in a dose- and time-dependent manner, a phenomenon which was prevented by co-incubation with L-arginine (1 mM). The aforementioned findings were accompanied by increased protein nitration, a measure for peroxynitrite accumulation. In contrast, no changes were observed in NO2/NO3 generation. CsA significantly decreased the abundance of CAT-1 protein, an effect that was attenuated by L-arginine. PKCα and phosphorylated PKCα (CAT-1 inhibitors) protein contents were not affected by CsA.

CONCLUSION

CsA inhibits arginine transport and induces protein nitration in HUVEC through modulation of CAT-1.

Care of undocumented-uninsured immigrants in a large urban dialysis unit

Background

Medical, ethical and financial dilemmas may arise in treating undocumented-uninsured patients with end-stage renal disease (ESRD). Hereby we describe the 10-year experience of treating undocumented-uninsured ESRD patients in a large public dialysis-unit.

Methods

We evaluated the medical files of all the chronic dialysis patients treated at the Tel-Aviv Medical Center between the years 2000–2010. Data for all immigrant patients without documentation and medical insurance were obtained. Clinical data were compared with an age-matched cohort of 77 insured dialysis patients.

Results

Fifteen undocumented-uninsured patients were treated with chronic scheduled dialysis therapy for a mean length of 2.3 years and a total of 4953 hemodialysis sessions, despite lack of reimbursement. All undocumented-uninsured patients presented initially with symptoms attributed to uremia and with stage 5 chronic kidney disease (CKD). In comparison, in the age-matched cohort, only 6 patients (8%) were initially evaluated by a nephrologist at stage 5 CKD. Levels of hemoglobin (8.5 ± 1.7 versus 10.8 ± 1.6 g/dL; p < 0.0001) and albumin (33.8 ± 4.8 versus 37.7 ± 3.9 g/L; p < 0.001) were lower in the undocumented-uninsured dialysis patients compared with the age-matched insured patients at initiation of hemodialysis therapy. These significant changes were persistent throughout the treatment period. Hemodialysis was performed in all the undocumented-uninsured patients via tunneled cuffed catheters (TCC) without higher rates of TCC-associated infections. The rate of skipped hemodialysis sessions was similar in the undocumented-uninsured and age-matched insured cohorts.

Conclusions

Undocumented-uninsured dialysis patients presented initially in the advanced stages of CKD with lower levels of hemoglobin and worse nutritional status in comparison with age-matched insured patients. The type of vascular access for hemodialysis was less than optimal with regards to current guidelines. There is a need for the national and international nephrology communities to establish a policy concerning the treatment of undocumented-uninsured patients with CKD.

Attenuated glomerular arginine transport prevents hyperfiltration and induces HIF-1α in the pregnant uremic rat

Pregnancy worsens renal function in females with chronic renal failure (CRF) through an unknown mechanism. Reduced nitric oxide (NO) generation induces renal injury. Arginine transport by cationic amino acid transporter-1 (CAT-1), which governs endothelial NO generation, is reduced in both renal failure and pregnancy. We hypothesize that attenuated maternal glomerular arginine transport promotes renal damage in CRF pregnant rats. In uremic rats, pregnancy induced a significant decrease in glomerular arginine transport and cGMP generation (a measure of NO production) compared with CRF or pregnancy alone and these effects were prevented by l-arginine. While CAT-1 abundance was unchanged in all experimental groups, protein kinase C (PKC)-α, phosphorylated PKC-α (CAT-1 inhibitor), and phosphorylated CAT-1 were significantly augmented in CRF, pregnant, and pregnant CRF animals; phenomena that were prevented by coadministrating l-arginine. α-Tocopherol (PKC inhibitor) significantly increased arginine transport in both pregnant and CRF pregnant rats, effects that were attenuated by ex vivo incubation of glomeruli with PMA (a PKC stimulant). Renal histology revealed no differences between all experimental groups. Inulin and p-aminohippurate clearances failed to augment and renal cortical expression of hypoxia inducible factor-1α (HIF-1α) significantly increased in CRF pregnant rat, findings that were prevented by arginine. These studies suggest that in CRF rats, pregnancy induces a profound decrease in glomerular arginine transport, through posttranslational regulation of CAT-1 by PKC-α, resulting in attenuated NO generation. These events provoke renal damage manifested by upregulation of renal HIF-1α and loss of the ability to increase glomerular filtration rate during gestation.