Long-term follow-up of an IgA nephropathy cohort: outcomes and risk factors

AIM

IgA nephropathy (IgAN), the most common glomerulopathy worldwide and in Uruguay, raised treatment controversies. The study aimed to analyze long-term IgAN outcomes and treatment.

METHODS

A retrospective analysis of a Uruguayan IgAN cohort, enrolled between 1985 and 2009 and followed up until 2020, was performed. The Ethics Committee approved the study. The inclusion criteria were (a) biopsy-proven IgAN; (b) age ≥12 years; and (c) available clinical, histologic, and treatment data. The patients were divided into two groups, with immunosuppressive (IS) or without (NoIS) treatment. Outcomes (end-stage kidney disease/kidney replacement therapy [ESKD/KRT] or all-cause death) were obtained from mandatory national registries.

RESULTS

The study population included 241 patients (64.7% men), median age 32 (19.5) years, baseline blood pressure <130/80 mmHg in 37%, and microhematuria in 67.5% of patients. Baseline proteinuria, glomerulosclerosis, and a higher crescent percentage were significantly more frequent in the IS group. Proteinuria improved in both groups. Renal survival at 20 years was 74.6% without difference between groups. In the overall population and in the NoIS group, bivariate Cox regression analysis showed that baseline proteinuria, endocapillary hypercellularity, tubule interstitial damage, and crescents were associated with a higher risk of ESKD/KRT or death, but in the IS group, proteinuria and endocapillary hypercellularity were not. In the multivariate Cox analysis, proteinuria in the NoIS group, crescents in the IS group and tubule interstitial damage in both groups were independent risk factors.

CONCLUSION

The IS group had more severe risk factors than the NoIS group but attained a similar outcome.

Low switched memory B cells are associated with no humoral response after SARS-CoV-2 vaccine boosters in kidney transplant recipients

Introduction

The humoral response after SARS-CoV-2 vaccination and boosters in kidney transplant recipients (KTRs) is heterogeneous and depends on immunosuppression status. There is no validated immune measurement associated with serological response in clinical practice. Multicolor flow cytometric immunophenotyping could be useful for measuring immune response. This study aimed to study B- and T-cell compartments through Standardized EuroFlow PID Orientation after SARS-CoV-2 vaccination and their association with IgG SARS-CoV-2 seropositivity status after two doses or boosters.

Methods

We conducted a multicenter prospective study to evaluate humoral response after SARS-CoV-2 vaccination in KTRs. Heterologous regimen: two doses of inactivated SARS-CoV-2 and two boosters of BNT162b2 mRNA (n=75). Homologous vaccination: two doses of BNT162b2 mRNA and one BNT162b2 mRNA booster (n=13). Booster doses were administrated to KTRs without taking into account their IgG SARS-CoV-2 seropositivity status. Peripheral blood samples were collected 30 days after the second dose and after the last heterologous or homologous booster. A standardized EuroFlow PID Orientation Tube (PIDOT) and a supervised automated analysis were used for immune monitoring cellular subsets after boosters.

Results

A total of 88 KTRs were included and divided into three groups according to the time of the first detected IgG SARS-CoV-2 seropositivity: non-responders (NRs, n=23), booster responders (BRs, n=41), and two-dose responders (2DRs, n=24). The NR group was more frequent on mycophenolate than the responder groups (NRs, 96%; BRs, 80%; 2DRs, 42%; p=0.000). Switched memory B cells in the 2DR group were higher than those in the BR and NR groups (medians of 30, 17, and 10 cells/ul, respectively; p=0.017). Additionally, the absolute count of central memory/terminal memory CD8 T cells was higher in the 2DR group than in the BR and NR groups. (166, 98, and 93 cells/ul, respectively; p=0.041). The rest of the T-cell populations studied did not show a statistical difference.

Conclusion

switched memory B cells and memory CD8 T-cell populations in peripheral blood were associated with the magnitude of the humoral response after SARS-CoV-2 vaccination. Boosters increased IgG anti-SARS-CoV-2 levels, CM/TM CD8 T cells, and switched MBCs in patients with seropositivity after two doses. Interestingly, no seropositivity after boosters was associated with the use of mycophenolate and a lower number of switched MBCs and CM/TM CD8 T cells in peripheral blood.

Comparison of antibody response to SARS-CoV-2 after two doses of inactivated virus and BNT162b2 mRNA vaccines in kidney transplant

Background

Antibody response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after mRNA or adenoviral vector-based vaccines is weak in kidney transplant (KT) patients. However, few studies have focused on humoral response after inactivated virus-based vaccines in KT. Here, we compare antibody response following vaccination with inactivated virus (CoronaVac®) and BNT162b2 mRNA.

Methods

A national multicentre cross-sectional study was conducted. The study group was composed of patients from all KT centres in Uruguay, vaccinated between 1 and 31 May 2021 (CoronaVac®, n = 245 and BNT162b2, n = 39). The control group was constituted of 82 healthy individuals. Participants had no prior confirmed coronavirus disease 2019 (COVID-19) test. Blood samples were collected between 30 and 40 days after the second dose. Serum-specific immunoglobulin G (IgG) antibodies against the receptor-binding domain (RBD) of SARS-CoV-2 Spike protein were determined using the COVID-19 IgG QUANT ELISA Kit.

Results

Only 29% of KT recipients showed seroconversion (36.5% BNT162b2, 27.8% inactivated virus, P = 0.248) in comparison with 100% in healthy control with either vaccine. Antibody levels against RBD were higher with BNT162b mRNA than with inactivated virus [median (interquartile range) 173 (73–554) and 29 (11–70) binding antibody units (BAU)/mL, P < 0.034] in KT and 10 times lower than healthy control [inactivated virus: 308 (209–335) and BNT162b2: 2638 (2608–3808) BAU/mL, P < 0.034]. In multivariate analysis, variables associated with negative humoral response were age, triple immunosuppression, estimated glomerular filtration rate and time post-KT.

Conclusion

Seroconversion was low in KT patients after vaccination with both platforms. Antibody levels against SARS-CoV-2 were lower with inactivated virus than BNT162b mRNA. These findings support the need for strategies to improve immunogenicity in KT recipients after two doses of either vaccine.

Association of Dietary Patterns with Cardiovascular and Kidney Phenotypes in an Uruguayan Population Cohort

The impact of habitual diet on chronic diseases has not been extensively characterized in South America. We aimed to identify major dietary patterns (DP) in an adult cohort in Uruguay (Genotype Phenotype and Environment of Hypertension Study—GEFA-HT-UY) and to assess associations with metabolic, anthropometric characteristics, and cardiovascular and kidney phenotypes. In a cross-sectional study (n = 294), DP were derived by the principal component analysis. Blood and urine parameters, anthropometrics, blood pressure, pulse wave velocity, and glomerular filtration rate were measured. Multivariable adjusted linear models and adjusted binary logistic regression were used. Three DP were identified (Meat, Prudent, Cereal and Mate) explaining 22.6% of total variance in food intake. The traditional Meat DP, characterized by red and barbecued meat, processed meat, bread, and soft drinks, was associated with worse blood lipid profile. Prudent DP, characterized by vegetables, fish, and nuts, and lower loads for bread and crackers, was associated with reduced risk of vitamin D deficiency. Cereal and Mate DP, was characterized by higher loads of cereals, bread, and crackers, and mate infusion, with higher odds of excessive body weight. No direct associations of dietary patterns with hypertension, arterial stiffness, chronic kidney disease, and nephrolithiasis were found in the studied population, nor by age categories or sex.

Substitution of Oral for Intravenous Cyclophosphamide in Membranous Nephropathy

Background

Optimal immunosuppressive treatment for membranous nephropathy is still a matter of controversy. Current recommendations include oral cyclophosphamide combined with steroids (modified Ponticelli regimen) as first-line treatment in patients who are high risk. However, concerns about the cumulative toxicity of oral cyclophosphamide persist. In the last 30 years, a protocol based on low-dose intravenous cyclophosphamide plus steroids has been used to treat membranous nephropathy in Uruguay. We aimed to assess the efficacy of this regimen to induce clinical remission in patients with membranous nephropathy.

Methods

In this retrospective, observational cohort study, we analyzed the outcome of 55 patients with membranous nephropathy treated between 1990 and 2017 with a 6-month course of alternating steroids (months 1, 3, and 5) plus intravenous cyclophosphamide (single dose of 15 mg/kg on the first day of months 2, 4, and 6).

Results

At 24 months, 39 (71%) patients achieved clinical response with complete remission observed in 23 patients (42%) and partial remission in 16 (29%). Median time to achieve partial and complete remission was 5.9 and 11.5 months, respectively. Absence of response was observed in 16 patients (29%), five of whom started chronic RRT after a median follow-up of 3.5 years. Clinical relapse occurred in nine of 33 (27%) patients at a median of 34 months after treatment discontinuation.

Conclusions

Replacement of oral cyclophosphamide with a single intravenous pulse on months 2, 4, and 6 of the modified Ponticelli regimen can be an effective and safe alternative for treatment of membranous nephropathy.

Podcast

This article contains a podcast at https://www.asn-online.org/media/podcast/K360/2020_09_24_KID0002802020.mp3

IgA Nephropathy in Elderly Patients

BACKGROUND AND OBJECTIVES

Some studies suggest that the incidence of IgA nephropathy is increasing in older adults, but there is a lack of information about the epidemiology and behavior of the disease in that age group.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this retrospective multicentric study, we analyzed the incidence, forms of presentation, clinical and histologic characteristics, treatments received, and outcomes in a cohort of 151 patients ≥65 years old with biopsy-proven IgA nephropathy diagnosed between 1990 and 2015. The main outcome was a composite end point of kidney replacement therapy or death before kidney replacement therapy.

RESULTS

We found a significant increase in the diagnosis of IgA nephropathy over time from six patients in 1990-1995 to 62 in 2011-2015 (P value for trend =0.03). After asymptomatic urinary abnormalities (84 patients; 55%), AKI was the most common form of presentation (61 patients; 40%). Within the latter, 53 (86%) patients presented with hematuria-related AKI (gross hematuria and tubular necrosis associated with erythrocyte casts as the most important lesions in kidney biopsy), and eight patients presented with crescentic IgA nephropathy. Six (4%) patients presented with nephrotic syndrome. Among hematuria-related AKI, 18 (34%) patients were receiving oral anticoagulants, and this proportion rose to 42% among the 34 patients older than 72 years old who presented with hematuria-related AKI. For the whole cohort, survival rates without the composite end point were 74%, 48%, and 26% at 1, 2, and 5 years, respectively. Age, serum creatinine at presentation, and the degree of interstitial fibrosis in kidney biopsy were risk factors significantly associated with the outcome, whereas treatment with renin-angiotensin-aldosterone blockers was associated with a lower risk. Immunosuppressive treatments were not significantly associated with the outcome.

CONCLUSIONS

The diagnosis of IgA nephropathy among older adults in Spain has progressively increased in recent years, and anticoagulant therapy may be partially responsible for this trend. Prognosis was poor.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2019_07_16_CJASNPodcast_19_08_.mp3.

Being Overweight Is Related to Faster Decline in Annual Glomerular Filtration Rate in Kidney Transplant

Few studies have examined the relationship between non-immunological factors and glomerular filtration rate (GFR) decline in kidney transplant. Correcting these factors in native kidneys slows the progression of chronic kidney disease. The aim of this study was to analyze the association between the control of non-immunological factors and the annual decline of GFR.

METHODS

A single-center, retrospective study was performed. We included 128 patients who received kidney transplants between 2000 and 2015, with at least 1-year post-transplant follow-up. Clinical records were reviewed. GFR was estimated by CKD-EPI. Three groups were defined according to the annual change in eGFR (ΔGFR 2016-1015): non-progressors (> -1 mL/min/1.73 m²), slow progressors (> -1 and < -5 mL/min/1.73 m²), and fast progressors (< -5 mL/min/1.73 m²). Percentage of achievement of KDIGO target was also analyzed.

RESULTS

The mean GFR was 62.5 mL/min/1.73 m². Glomerulonephritis was the most common cause of kidney failure (36%). When the fast progressor group was compared with the non-progressor group, they differed significantly in age-patients were younger (40 ± 12.3 vs 45 ± 13.1 years)-post-transplant body mass index (27.4 ± 5.6 vs 25.2 x ± 5.9 kg/m²), and serum uric acid, which was significantly higher (6.4 ± 1.7 vs 5.5 ± 1.58 mg/dL). There were no differences between the groups with regard to blood pressure, dyslipidemia, proteinuria, or venous bicarbonate. Target systolic blood pressure was achieved by 45% of patients. Biopsy-proven acute rejection was higher in the fast progression group, although this was not statistically significant (13 [24.5%] vs 8 [13.1%]).

CONCLUSIONS

High body mass index was associated with a faster decline in glomerular filtration rate in this study. Target blood pressure <140/90 mm Hg was achieved in less than 50% of cases.

Blood Pressure in relation to 24-Hour Urinary Sodium and Potassium Excretion in a Uruguayan Population Sample

Many public health policies in Latin America target an optimized sodium and potassium intake. The aims of this study were to assess the sodium and potassium intake using 24-hour urinary analysis and to study their association with blood pressure in a Uruguayan population cohort using cluster analysis. A total of 149 participants (aged 20-85 years) were included in the study, and office blood pressure, anthropometric measurements, biochemical parameters in the blood, and 24-hour urine samples were obtained. The overall mean sodium and potassium excretion was 152.9 ± 57.3 mmol/day (8.9 ± 3.4 g/day of salt) and 55.4 ± 19.6 mmol/day, respectively. The average office systolic/diastolic blood pressure was 124.6 ± 16.7/79.3 ± 9.9 mmHg. Three compact spherical clusters were defined in untreated participants based on predetermined attributes, including blood pressure, age, and sodium and potassium excretion. The major characteristics of the three clusters were (1) high systolic blood pressure and moderate sodium excretion, (2) moderate systolic blood pressure and very high sodium excretion, and (3) low systolic blood pressure and low sodium excretion. Participants in cluster three had systolic blood pressure values that were 23.9 mmHg (95% confidence interval: -29.5 to -1.84) lower than those in cluster one. Participants in cluster two had blood pressure levels similar to those in cluster one (P = 0.32) and worse metabolic profiles than those in cluster one and three (P < 0.05). None of the clusters showed high blood pressure levels and high sodium excretion. No linear association was found between blood pressure and urinary sodium excretion (r < 0.14; P > 0.47). An effect of sodium and potassium intake on blood pressure levels was not found at the population level using regression or cluster analysis.

Temporal trends in biopsy proven glomerular disease in Uruguay, 1990-2014

Our aim is to describe variations in the incidence rates of glomerular disease diagnosed by renal biopsies performed in Uruguay over the last 25 years in relation to sex, age, clinical presentation and histological diagnosis. We analyzed all renal biopsies performed in Uruguay during the 25 years period and estimated incidence rates per million people per year (pmp/yr) for the population older than 14 years. Mann Kendall's trend analysis was used to assess incidence trends. In order to identify changes in trends, we compared annual incidence rates with the Joinpoint method. From 1990 to 2014, 3390 biopsies of native kidneys corresponding to glomerular disease were performed in patients older than 14 years. The average biopsy rate was 58 per pmp/yr. The glomerular disease incidence rate increased progressively over the period (p<0.05). Trends analysis over five-year periods demonstrated a progressive increase of IgA nephropathy (3.08 pmp/yr 1990-1994 to 12.53 pmp/yr 2010-2014 p<0.05), membranous nephropathy (2.38 pmp/yr 1990-1994 to 8.04 pmp/yr 2010-2014 p< 0.05) and lupus nephritis (4,23 pmp/yr 1990-1994 to 7,81 pmp/yr 2010-2014 p<0.05). There was a change in the trend of focal segmental glomerular sclerosis (FSGS) which increased until 1996 and decreased afterwards. The incidence rates of glomerular disease have doubled globally in the last quarter of a century in Uruguay, mainly related to the increase of IgA nephropathy, membranous nephropathy and lupus nephritis. There was a change in the slope of the incidence rate of FSGS.

Lupus Nephritis in Males: Clinical Features, Course, and Prognostic Factors for End-Stage Renal Disease

Introduction

Because of their rarity in men, systemic lupus erythematous and lupus nephritis (LN) are poorly understood in men. Our aim was to analyze the clinical presentation and course of histology-proven systemic lupus erythematous and LN in males and to determine the risk factors for progression to end-stage renal disease.

Methods

Fifty patients from 2 historical cohorts in Spain (Hospital 12 de Octubre) and Uruguay were retrospectively analyzed and compared with a female cohort matched for age and disease characteristics.

Results

The median age at the time of renal biopsy was 27 years (range, 8-79 years). The main forms of presentation were nephrotic syndrome in 26 of 50 patients (52%), and class IV LN in 34 of 50 (68%). After treatment, 21 patients (45.6%) achieved complete renal remission. During follow-up, 12 patients required renal replacement therapy, and 3 patients died of infectious causes. When patients who required renal replacement therapy were compared with those who did not require it, several parameters showed significant differences (P < 0.05) at the time of renal biopsy: estimated glomerular filtration rate < 60 ml/min, hypertension, hypoalbuminemia, and concomitant visceral involvement (neurologic, cardiovascular, and/or pulmonary). In the multivariate analysis, only estimated glomerular filtration rate < 60 ml/min persisted as a risk factor for progression to end-stage renal disease. When compared with a cohort of female patients with LN, there were no significant differences in remission or renal survival.

Discussion

LN in males usually presents as nephrotic syndrome, and type IV LN is the most frequent form. An estimated glomerular filtration rate < 60 ml/min at the time of renal biopsy is associated with poor renal outcomes. There were no differences in remission or progression of LN in males when compared with a cohort of female patients with LN.

Successful Pregnancies in Kidney Transplant Recipients: Experience of the National Kidney Transplant Program From Uruguay

BACKGROUND

Renal transplantation increases the possibilities of pregnancy in women of reproductive age. The course of pregnancy was analyzed retrospectively in patients with kidney or kidney-pancreas transplant, surveying maternal-fetal or renal graft complications and the relation with pre-pregnancy renal function.

METHODS

A cohort that includes all the kidney transplant recipients who went through pregnancy in Uruguay in a period of 28 years is described. Forty pregnancies in 32 patients were registered; the average time between the kidney transplant and the beginning of the gestation period was 47 months. From the total gestations, 10 abortions, 1 neonatal death, and 1 fetal demise were registered. From the remaining pregnancies, we highlight prematurity (18/29) and low birth weight (14/21). Twenty-nine in 30 pregnancies ended in cesarean section; in 8 of 30, pre-eclampsia diagnosis was performed. Acute rejection was diagnosed in 2 of 30 pregnancies, both undergoing their first post-transplant year.

RESULTS

Two patients required dialysis throughout the pregnancy because of progress into severe renal insufficiency. Higher obstetric perinatal morbidity and renal function deterioration was related to lower pre-pregnancy glomerular filtration rate (GFR).

CONCLUSIONS

A successful pregnancy is possible in transplant recipients, yet there are risks of prematurity, low birth weight, and abortion. A lower GFR before pregnancy was associated with poorer maternal and perinatal results as shown in the different series.

Reliable Quantification of the Potential for Equations Based on Spot Urine Samples to Estimate Population Salt Intake: Protocol for a Systematic Review and Meta-Analysis

Background

Methods based on spot urine samples (a single sample at one time-point) have been identified as a possible alternative approach to 24-hour urine samples for determining mean population salt intake.

Objective

The aim of this study is to identify a reliable method for estimating mean population salt intake from spot urine samples. This will be done by comparing the performance of existing equations against one other and against estimates derived from 24-hour urine samples. The effects of factors such as ethnicity, sex, age, body mass index, antihypertensive drug use, health status, and timing of spot urine collection will be explored. The capacity of spot urine samples to measure change in salt intake over time will also be determined. Finally, we aim to develop a novel equation (or equations) that performs better than existing equations to estimate mean population salt intake.

Methods

A systematic review and meta-analysis of individual participant data will be conducted. A search has been conducted to identify human studies that report salt (or sodium) excretion based upon 24-hour urine samples and spot urine samples. There were no restrictions on language, study sample size, or characteristics of the study population. MEDLINE via OvidSP (1946-present), Premedline via OvidSP, EMBASE, Global Health via OvidSP (1910-present), and the Cochrane Library were searched, and two reviewers identified eligible studies. The authors of these studies will be invited to contribute data according to a standard format. Individual participant records will be compiled and a series of analyses will be completed to: (1) compare existing equations for estimating 24-hour salt intake from spot urine samples with 24-hour urine samples, and assess the degree of bias according to key demographic and clinical characteristics; (2) assess the reliability of using spot urine samples to measure population changes in salt intake overtime; and (3) develop a novel equation that performs better than existing equations to estimate mean population salt intake.

Results

The search strategy identified 538 records; 100 records were obtained for review in full text and 73 have been confirmed as eligible. In addition, 68 abstracts were identified, some of which may contain data eligible for inclusion. Individual participant data will be requested from the authors of eligible studies.

Conclusions

Many equations for estimating salt intake from spot urine samples have been developed and validated, although most have been studied in very specific settings. This meta-analysis of individual participant data will enable a much broader understanding of the capacity for spot urine samples to estimate population salt intake.

The Diurnal Profile of Central Hemodynamics in a General Uruguayan Population

BACKGROUND

No previous population study assessed the diurnal profile of central arterial properties.

METHODS

In 167 participants (mean age, 56.1 years; 63.5% women), randomly recruited in Montevideo, Uruguay, we used the oscillometric Mobil-O-Graph 24-h PWA monitor to measure peripheral and central systolic (SBP), diastolic (DBP), and pulse (PP) pressures and central hemodynamics standardized to a heart rate of 75 bpm, including aortic pulse wave velocity, systolic augmentation (first/second peak × 100), and pressure amplification (peripheral PP/central PP).

RESULTS

Over 24 hours, day and night, peripheral minus central differences in SBP/DBP and in PP averaged 12.2/-1.1, 14.0/-0.7, and 9.7/0.2mm Hg and 12.6, 14.7, and 9.5mm Hg, respectively (P < 0.001 except for nighttime DBP (P = 0.38)). The central-to-peripheral ratios of SBP, DBP, and PP were 0.89, 1.00, and 0.70 unadjusted, but after accounting for anthropometric characteristics decreased to 0.74, 0.97, and 0.63, respectively, with strong influence of height for SBP and DBP and of sex for PP. From day (10-20h) to nighttime (0-6h), peripheral (-10.4/-10.5 mm Hg) and central (-6.0/-11.3mm Hg) SBP/DBP, pulse wave velocity (-0.7 m/s) and pressure amplification (-0.05) decreased (P < 0.001), whereas central PP (+5.3mm Hg) and systolic augmentation (+2.3%) increased (P < 0.001).

CONCLUSIONS

The diurnal rhythm of central pressure runs in parallel with that of peripheral pressure, but the nocturnal fall in SBP is smaller centrally than peripherally. pulse wave velocity, systolic augmentation, and pressure amplification loop through the day with high pulse wave velocity and pressure amplification but low systolic augmentation in the evening and opposite trends in the morning.

Acute Antibody-Mediated Rejection in Kidney Transplant Based on the 2013 Banff Criteria: Single-Center Experience in Uruguay

BACKGROUND

Acute antibody-mediated rejection (AMR) diagnosis criteria have changed in recent consensus of Banff, with current evidence of C4d-negative AMR. Our objective was to evaluate incidence of AMR in renal transplantation according to Banff 2013 criteria and to examine the histological features and outcome.

METHODS

This retrospective study involved all kidney transplants with histological diagnosis of acute rejection (AR) at our center between 2000 and 2014. All the biopsies with AR were re-assessed by a nephro-pathologist and classified by use of the Banff 2013 criteria.

RESULTS

Of 205 kidney transplants, biopsy-proven AR was diagnosed in 25 cases (12%). Re-assessing them according to Banff 2013 criteria, AMR was diagnosed in 17 (8.3%) and represented 68% of the confirmed rejections. AMR diagnosis was performed on day 23 ± 26, with median of 11 days. From the 17 cases, 7 had concomitant T-cell-mediated rejection. All cases presented endothelial edema and acute tubular necrosis. Glomerulitis was found in 12 cases and capillaritis in 14. In 3, associated thrombotic micro-angiopathy (TMA) was found. Intimal and transmural arteritis was evidenced in 5 and 1 patient. In 2, transplant glomerulopathy was present. Seven of the 10 biopsies with C4d staining in the peri-tubular capillaries were positive. Twelve cases received plasmapheresis, 6 received gamma-globulin, and 6 received rituximab. After administration of anti-AMR therapy, 16 cases recovered renal function, reaching a serum creatinine level of 1.5 ± 0.6 mg %. Graft survival at 1 year was lower in the AMR group versus patients without AMR (81.9% vs 98.9%, log-rank test, P < .001). Risk factors for AMR were re-transplant (30% vs 7%, P = .02), HLA-DR mismatch (1.06 ± 0.65 vs 0.7 ± 0.6, P = .03), panel-reactive antibody (28% ± 33 vs 6.2 ± 13, P = .00), and delayed graft function (82% vs 30%, P = .00).

CONCLUSIONS

Adapting the new Banff 2013 criteria increased the sensitivity of the diagnosis of ARM. Regarding our data, despite an adequate response to the therapy, it resulted in a worse graft survival by the first year of renal transplant.

Development of the National Kidney Transplantation Program in Uruguay

The first kidney transplantation (KT) in Uruguay was performed in 1969. We report the rates of KT and survival of patients and grafts up to December 2014. The country has a surface of 176,215 km(2) and a population of 3,286,314 inhabitants (18.6 inhabitants per km(2)). Till December 31, 2014, 1,940 KT have been performed in Uruguay (41.8 pmp that year); 90.4% of them were from cadaveric donors (CD). Median age of recipients (R) was 44 ± 14 years; R older than 55 years increased from 0 to 27% during the period. Our pre-emptive KT program started in 2007. Optimal donors (D) decreased from 65.2% to 35.5%, and D older than 45 years old increased from 9% to 37%. Trauma as cause of death decreased from 49% to 32% and stroke as cause of death increased from 25% to 39%. Patient survival rates at 1, 5, and 8 years were 93%, 87%, and 78%, respectively for KT performed between 1980 and 1989; they were 98%, 93%, and 89%, respectively, for KT performed between 1990 and1999; they were 97%, 91%, and 90%, respectively, for KT performed between 2000 and 2010. In December 2013, there were 1098 patients pmp in renal replacement therapy, 758 pmp in dialysis, and 340 pmp (30.9%) with a functioning graft. Our national KT program is mainly based (90.6%) on cadaveric donation. Epidemiological changes in the characteristics of R and D followed the changes in aging that occurred in the general population and the dialysis population. The survival rates from patients and kidneys are similar to those reported by the European and the American registries.

Mechanisms of Salt-Sensitive Hypertension

Hypertension and its consequences, including heart failure, stroke, and kidney disease, are responsible for substantial morbidity and mortality worldwide. Lifestyle changes, particularly sodium reduction, contribute to blood pressure control. However, not all individuals, whether normotensive or hypertensive, have the same susceptibility to the effects of salt. While a variety of approaches have been proposed to identify salt sensitive patients, there is no consensus for a definition of salt sensitivity and the precise mechanisms that explain their association are not yet fully understood. In this review we summarize the current understanding of the various pathophysiological mechanisms potentially involved in determining the salt sensitive phenotype. Genetic, neuronal, and immune alterations are reviewed. Additionally, we provide an update on the current knowledge of a new approach proposing the interstitium of the skin may act as a sodium reservoir. The role of dietary potassium on salt sensitive hypertension is also summarized.

Online Continuing Medical Education for the Latin American Nephrology Community

A continuing medical education (CME) course was implemented for Latin American nephrologists in 2013. The topic was Immunopathology in native and transplanted kidneys. The course was given in Spanish and Portuguese. The activities included a distance education seven-week asynchronous online modality with multiple educational strategies. Thirty hours of study workload were estimated to complete the course. Four hundred and ninety-eight physicians coming from 18 countries registered for the course; 442 of them participated in it. Of those who participated, 51% received a certificate of completion and 29% a certificate of participation. Sixty-five percent of registrants participated in the case discussions. Eighty-six percent were very satisfied and 13% were satisfied. Lack of time to devote to the course was the main limitation expressed (62%), while Internet access or difficulties in the use of technology were considered by only 12 and 6% of participants, respectively. There was a significant increase in knowledge between before and after the course; the average grade increased from 64 to 83%. In conclusion, technology-enabled education demonstrated potential to become an instrument for Latin American nephrologists.

[Severe hypokalemic rhabdomyolysis. Report of six cases]

Rhabdomyolysis results from acute necrosis of skeletal muscle fibers and consequent leakage of muscle constituents into the circulation. It ranges from an asymptomatic state to a severe condition associated with extreme elevations in creatine kinase and acute renal failure. Reported etiologies of rhabdomyolysis include alcohol abuse, drugs, muscle trauma and muscle overexertion. Less common causes include muscle enzyme deficiencies, electrolyte abnormalities, infectious causes, toxins and endocrine disorders. Hypokalemia is a rare cause of rhabdomyolysis. We report six patients aged 31 to 57 years (three women) with a severe hypokalemic rhabdomyolysis, secondary to chronic diarrhea in two patients, treatment with loop diuretics in one and Gitelman syndrome in three. Rhabdomyolysis may be underdiagnosed in the context of hypokalemia, because the neuromuscular symptoms can be attributed solely to the electrolyte disorder.

Anti-glomerular basement membrane antibodies

Basement membranes form an anatomic barrier that contains connective tissue. They are composed of type IV collagen, laminin and proteoglycans. Anti-basement membrane antibodies bind to the non-collagen site of the α3 chain of type IV collagen. A group of renal diseases, pulmonary diseases and perhaps others affecting different organs have long been associated with the presence of antibodies directed against glomerular basement membrane (GBM), alveolar basement membrane and tubular basement membrane. Goodpasture disease has a frequency of 0.5 to 1 case by million/year, and is responsible for up to 20% of crescentic glomerulonephritis in renal biopsy. It has been associated with genetic and immune abnormalities and there are usually environmental triggers preceding clinical onset. Renal disease can occur isolated or in association with pulmonary hemorrhage. In general, renal disease has a rapid progression that determines severe compromise, with rare spontaneous resolution. The diagnosis of Goodpasture disease requires the presence of the anti-GBM antibody, either in circulation or in renal tissue. The prognosis of non-treated patients is poor. The standard of care is plasma exchange combined with prednisone and cyclophosphamide. Anti-GBM antibody levels must be monitored frequently until their disappearance, and then every 6 months to confirm sustained remission in the absence of clinical signs of recurrence. Prognosis of the disease is strongly associated with its initial presentation. Survival rates are related to the degree of renal compromise at onset of the disease. Recurrence of the disease post-transplantation is low.

Delayed mTOR inhibition with low dose of everolimus reduces TGFβ expression, attenuates proteinuria and renal damage in the renal mass reduction model

Background

The immunosuppressive mammalian target of rapamycin (mTOR) inhibitors are widely used in solid organ transplantation, but their effect on kidney disease progression is controversial. mTOR has emerged as one of the main pathways regulating cell growth, proliferation, differentiation, migration, and survival.

The aim of this study was to analyze the effects of delayed inhibition of mTOR pathway with low dose of everolimus on progression of renal disease and TGFβ expression in the 5/6 nephrectomy model in Wistar rats.

Methods

This study evaluated the effects of everolimus (0.3 mg/k/day) introduced 15 days after surgical procedure on renal function, proteinuria, renal histology and mechanisms of fibrosis and proliferation.

Results

Everolimus treated group (EveG) showed significantly less proteinuria and albuminuria, less glomerular and tubulointerstitial damage and fibrosis, fibroblast activation cell proliferation, when compared with control group (CG), even though the EveG remained with high blood pressure. Treatment with everolimus also diminished glomerular hypertrophy.

Everolimus effectively inhibited the increase of mTOR developed in 5/6 nephrectomy animals, without changes in AKT mRNA or protein abundance, but with an increase in the pAKT/AKT ratio. Associated with this inhibition, everolimus blunted the increased expression of TGFβ observed in the remnant kidney model.

Conclusion

Delayed mTOR inhibition with low dose of everolimus significantly prevented progressive renal damage and protected the remnant kidney. mTOR and TGFβ mRNA reduction can partially explain this anti fibrotic effect. mTOR can be a new target to attenuate the progression of chronic kidney disease even in those nephropathies of non-immunologic origin.

Rust urine after intense hand drumming is caused by extracorpuscular hemolysis

BACKGROUND AND OBJECTIVES

During Carnival, groups of > or =60 drummers go drumming with their hands and marching for periods of 2 to 4 h. The objective of this study was to determine the frequency and type of urinary abnormalities after candombe drumming and to evaluate possible pathogenic mechanisms.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

For analysis of pathogenic mechanisms, a group of individuals were prospectively evaluated before and after candombe drumming.

METHODS

Candombe drummers were recruited in January 2006, 1 wk before prolonged drumming. After clinical evaluation, urine and blood samples were obtained before and immediately after drumming.

RESULTS

Forty-five healthy individuals (four women and 41 men), median age 31 yr (14 to 56), were evaluated. Predrumming urine and plasma samples were obtained for 30 individuals. Nineteen (42%) of 45 had a previous history of rust urine emission temporally related with candombe drumming. After drumming, 18 of 26 showed urine abnormalities; six of 26 showed rust urine, eight of 26 had microhematuria, and seven of 26 had proteinuria >1 g/L. The candombe drummers who showed rust urine after heavy drumming presented significantly higher levels of lactate dehydrogenase and total bilirubin when compared with those without urine abnormalities. Haptoglobin was significantly lower in the rust urine group. Fragmented red cells were observed in the blood smear of individuals with rust urine. Rust urine after drumming was associated with previous episodes of rust urine and glucosuria.

CONCLUSIONS

Taken together, these data confirm that rust urine is caused by extracorpuscular hemolysis.

[Frequency of diagnosis and clinic presentation of glomerulopathies in Uruguay]

The Uruguayan Registry of Glomerulopathies began its activity in 1974 and since 1985 is a national registry. The aim of this report is to analyze the incidence and the variations in frequencies of the histological diagnosis and clinical presentation during the 1980-2003 period.

PATIENTS AND METHODS

From the 2,058 patients with renal biopsy in the whole period, we analyzed the histological diagnosis and the following data has been collected when the patients were registered: age, gender, clinical syndrome, proteinuria, hematuria, serum creatinine, blood pressure and time from the first symptom. Four periods of registry entry were considered: 1980-1989, 1990-1994, 1995-1999 and 2000-2003. Chi-square and Student test for independent samples were used to evaluate the differences among the variables frequencies in the four periods.

RESULTS

The incidence of registered glomerulopathies per million population (pmp) increased from 13 (1980-1989) to 43 (2000-2003). In the 2000-2003 period, the incidences pmp were: primary glomerulopathy (PG), 25.3 and secondary glomerulopathy, 14.2. The highest incidences pmp were: focal and segmental glomeruloesclerosis (FSGS) 6.4; vasculitis 5.4; lupus nephritis 4.6; minimal change disease (MCD) 4.6; IgA nephropathy (IgAN) 4.5; and membranous nephropathy (MN) 4.0. The most frequent PG were the FSGS (29.3%) and the MCID (19.6%). The FSGS frequency decreased from 36.3% in 1995-1999 to 19.1% in 2000-2003. The IgAN frequency increased from 5.2% in 1980-1989 to 17.5% in 2000-2003. Nephrotic syndrome was the most frequent clinical presentation; its frequency was over 30% in the four periods. Asymptomatic urinary abnormality frequency increased from 14.0% in 1980-1989 to 22.7% in 2000-2003. The frequency of serum creatinine under 1.5 mg/dl, increased from 42.2% in 1980-1989 to 67.2% in 2000-2003 (p = 0.001). The frequency of serum creatinine over 6.0 mg/dl, decreased from 19.3% in 1990-1994 to 7.2% in 2000-2003. The percentage of patients referred since the first month of the apparent onset of the disease increased from 24.0% in 1980-1989 to 40.1% in 2000-2003 (p < 0.001).

CONCLUSIONS

In Uruguay, the incidence of glomerulopathies with histological diagnosis has increased and the frequency of the different types has changed. Several indicators seem to show that the reference of patients to the nephrologist tended to be earlier in the last years.

Calcium citrate ameliorates the progression of chronic renal injury

BACKGROUND

Metabolic acidosis is a consequence of chronic renal failure and it may produce bone demineralization, muscle proteolysis, and progression of chronic renal failure. The aim of this study was to evaluate the effects of correction of metabolic acidosis with calcium citrate in an experimental model of renal mass ablation.

METHODS

Wistar rats were subjected to 5/6 nephrectomy and were randomly assigned to one of 4 groups: nontreated (NFX); treated with calcium citrate (1.45 g/100 g feed) (NFX-CIT); treated with captopril (500 mg/L water) (NFX-CAP); or treated with both (NFX-CAP-CIT) during 1, 10, or 20 weeks. Body weight, systolic blood pressure, proteinuria, arterial bicarbonate concentration, urine citrate excretion, plasma calcium, and inulin clearance were measured. Histologic glomerular and tubulointerstitial damage scores were measured at 1, 10, and 20 weeks, and glomerular and tubular proliferating cell nuclear antigen (PCNA)-positive cells, alpha-smooth muscle actin, and desmin staining were studied by immunohistochemistry at 1 and 10 weeks.

RESULTS

The treated groups showed significantly less glomerular and tubulointerstitial cellular proliferation in the first week (P < 0.05), less glomerular cell transdifferentiation and higher plasma bicarbonate at 10 weeks (P < 0.05), as well as diminished histologic glomerular and tubulointerstitial damage scores at 20 weeks (P < 0.05). Inulin clearances were higher (P < 0.05), and urine protein excretion rates were lower (P < 0.05) than in the NFX non-treated group, but arterial blood pressure was not significantly different in the NFX-CIT group.

CONCLUSION

Calcium citrate slows the progression of chronic renal injury in the 5/6 NFX model. It improves metabolic acidosis and diminishes cell proliferation and transdifferentiation without changes in systolic blood pressure.