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1.
Nat Commun ; 10(1): 4130, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31511532

RESUMO

Increased levels of the urinary albumin-to-creatinine ratio (UACR) are associated with higher risk of kidney disease progression and cardiovascular events, but underlying mechanisms are incompletely understood. Here, we conduct trans-ethnic (n = 564,257) and European-ancestry specific meta-analyses of genome-wide association studies of UACR, including ancestry- and diabetes-specific analyses, and identify 68 UACR-associated loci. Genetic correlation analyses and risk score associations in an independent electronic medical records database (n = 192,868) reveal connections with proteinuria, hyperlipidemia, gout, and hypertension. Fine-mapping and trans-Omics analyses with gene expression in 47 tissues and plasma protein levels implicate genes potentially operating through differential expression in kidney (including TGFB1, MUC1, PRKCI, and OAF), and allow coupling of UACR associations to altered plasma OAF concentrations. Knockdown of OAF and PRKCI orthologs in Drosophila nephrocytes reduces albumin endocytosis. Silencing fly PRKCI further impairs slit diaphragm formation. These results generate a priority list of genes and pathways for translational research to reduce albuminuria.

2.
Diabetes Care ; 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31488569

RESUMO

OBJECTIVE: To study whether fibroblast growth factor 23 (FGF23) is associated with adverse outcomes in patients with type 2 diabetes and normal or mildly impaired kidney function. RESEARCH DESIGN AND METHODS: We analyzed COOH-terminal FGF23 levels in 310 patients with type 2 diabetes and estimated glomerular filtration rate ≥60 mL/min/1.73 m2. Associations of FGF23 with all-cause mortality and major adverse cardiovascular events (MACE) were studied by Cox regression. RESULTS: During a follow-up of 5.8 years (3.3-6.5), 47 patients developed MACE and 28 patients died. FGF23 was associated with an increased risk of all-cause mortality (age- and sex-adjusted hazard ratio 2.78 [95% CI 1.76-4.40]) and MACE (1.67 [1.12-2.49]). Results were similar after additional adjustment for other potential confounders and were consistent upon replication in an independent cohort. CONCLUSIONS: In patients with type 2 diabetes and normal or mildly impaired kidney function, FGF23 is associated with an increased risk of cardiovascular events and mortality.

3.
Amino Acids ; 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31535220

RESUMO

L-Arginine:glycine amidinotransferase (AGAT) is the main producer of the creatine precursor, guanidinoacetate (GAA), and L-homoarginine (hArg). We and others previously reported lower levels of circulating and urinary hArg in renal transplant recipients (RTR) compared to healthy subjects. In adults, hArg emerged as a novel risk factor for renal and cardiovascular adverse outcome. Urinary GAA was found to be lower in children and adolescents with kidney transplants compared to healthy controls. Whether GAA is also a risk factor in the renal and cardiovascular systems of adults, is not yet known. In the present study, we aimed to investigate the significance of circulating GAA and the GAA-to-hArg molar ratio (GAA/hArg) in adult RTR. We hypothesized that GAA/hArg represents a measure of the balanced state of the AGAT activity in the kidneys, and would prospectively allow assessing a potential association between GAA/hArg and long-term outcome in RTR. The median follow-up period was 5.4 years. Confounders and potential mediators of GAA/hArg associations were evaluated with multivariate linear regression analyses, and the association with all-cause and cardiovascular mortality or death-censored graft loss was studied with Cox regression analyses. The study cohort consisted of 686 stable RTR and 140 healthy kidney donors. Median plasma GAA concentration was significantly lower in the RTR compared to the kidney donors before kidney donation: 2.19 [1.77-2.70] µM vs. 2.78 [2.89-3.35] µM (P < 0.001). In cross-sectional multivariable analyses in RTR, HDL cholesterol showed the strongest association with GAA/hArg. In prospective analyses in RTR, GAA/hArg was associated with a higher risk for all-cause mortality (hazard ratio (HR): 1.35 [95% CI 1.19-1.53]) and cardiovascular mortality (HR: 1.46 [95% CI 1.24-1.73]), independent of potential confounders. GAA but not GAA/hArg was associated with death-censored graft loss in crude survival and Cox regression analyses. The association of GAA and death-censored graft loss was lost after adjustment for eGFR. Our study suggests that in the kidneys of RTR, the AGAT-catalyzed biosynthesis of GAA is decreased. That high GAA/hArg is associated with a higher risk for all-cause and cardiovascular mortality may suggest that low plasma hArg is a stronger contributor to these adverse outcomes in RTR than GAA.

4.
PLoS One ; 14(8): e0220368, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31393962

RESUMO

BACKGROUND: Multimorbidity is considered a major challenge for current health care. Lifestyle interventions, as a broad and generic approach, may have the potential to improve the management of care among patients with multimorbidity. The objective of this study was to evaluate the association of multimorbidity defined within the cardiometabolic disease domains with dietary patterns, representing habitual dietary intake. DESIGN: We studied 129 369 participants from the Lifelines Cohort study (42% male, 45±13 years (range 18-93)) in which diet was assessed using a 110-item food frequency questionnaire. A composite morbidity score was applied in multivariable ordered logistic regression to test the association with dietary patterns derived by principal components analysis, based on sex-specific dietary pattern scores. RESULTS: Four dietary patterns were retained, accounting for 26.6% of the variation in overall diet. After control for potential confounders, men and women in the highest quintile of "meat, alcohol and potato pattern" and "snack pattern" had a higher likelihood of having higher morbidity scores than those in the lowest quintile (e.g. men: OR = 1.83(95% CI:1.71-1.97), OR = 1.18(95% CI 1.11-1.27 respectively). The opposite was observed with respect to the "bread and sweets pattern" and "vegetable, fish and fruit pattern" (e.g. women: OR = 0.88(95% CI: 0.81-0.96), OR = 0.86(95% CI 0.81-0.92 respectively). The association partially attenuated after adjusting for BMI, but the associations remained significant among men. CONCLUSIONS: Robust associations between dietary patterns and multimorbidity within the cardiometabolic domain, in particular a "meat, alcohol and potato pattern", suggest an important opportunity of dietary interventions in multimobidity prevention. Generic prevention strategies based on population derived dietary patterns may have the potential to enhance lifestyle management among people with multimorbidity.

5.
Am J Clin Nutr ; 110(3): 641-651, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31274143

RESUMO

BACKGROUND: There is growing interest in assessing a population's prevalence of inadequate nutrient intake using biomarkers. However, within-person variation is generally ignored because repeated data collections are considered costly and burdensome. OBJECTIVES: The study aimed to show the importance of estimating, from repeated 24-h urine collections, a population's habitual salt intake and to explore the potential of using the ratio of within-person variance to total variance from an external source (W:T variance) with single 24-h urine collection. METHODS: Salt intake was predicted from data for 24-h urinary sodium excretion in adult kidney transplant recipients in 1992-1997 (n = 432) and 2006-2011 (n = 1159). The salt intake distribution of single-day measurements was compared with estimates from multiple 24-h urine collections, which were statistically corrected for within-person variance. Habitual salt intake was also estimated using single-day measurements and external variance estimates. From each distribution, the proportion below specified cut-off values was estimated. RESULTS: In 2006-2011 the average habitual salt intake was 10.6 g/d (men) and 8.5 g/d (women); in 1992-1997 these values were 8.6 g/d and 7.5 g/d, respectively. The proportion with salt intake <6 g/d was 5% and 13% in 2006-2011 and 22% and 28% in 1992-1997, respectively, for men and women. Correction for within-person variance significantly narrowed the salt intake distribution-the proportion with salt intake <6 g/d was overestimated by 3-13 percentage points using single-day data. Sensitivity analyses showed the importance of a sufficient sample size for estimating variance components. Variation of the W:T variance showed up to 40 percentage points deviation in the proportion with intakes below a specified cut-off value. CONCLUSIONS: To estimate a population's salt intake distribution, it is important to correct 24-h urinary sodium excretion for within-person variance. Predicting habitual salt intake distribution using single-day measurements with external variances is promising; a sensitivity analysis is recommended to show the effect of different external variances.

6.
PLoS Med ; 16(6): e1002818, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31170159

RESUMO

BACKGROUND: Emerging data in chronic kidney disease (CKD) patients suggest that iron deficiency and higher circulating levels of erythropoietin (EPO) stimulate the expression and concomitant cleavage of the osteocyte-derived, phosphate-regulating hormone fibroblast growth factor 23 (FGF23), a risk factor for premature mortality. To date, clinical implications of iron deficiency and high EPO levels in the general population, and the potential downstream role of FGF23, are unclear. Therefore, we aimed to determine the associations between iron deficiency and higher EPO levels with mortality, and the potential mediating role of FGF23, in a cohort of community-dwelling subjects. METHODS AND FINDINGS: We analyzed 6,544 community-dwelling subjects (age 53 ± 12 years; 50% males) who participated in the Prevention of Renal and Vascular End-Stage Disease (PREVEND) study-a prospective population-based cohort study, of which we used the second survey (2001-2003)-and follow-up was performed for a median of 8 years. We measured circulating parameters of iron status, EPO levels, and plasma total FGF23 levels. Our primary outcome was all-cause mortality. In multivariable linear regression analyses, ferritin (ß = -0.43), transferrin saturation (TSAT) (ß = -0.17), hepcidin (ß = -0.36), soluble transferrin receptor (sTfR; ß = 0.33), and EPO (ß = 0.28) were associated with FGF23 level, independent of potential confounders. During median (interquartile range [IQR]) follow-up of 8.2 (7.7-8.8) years, 379 (6%) subjects died. In multivariable Cox regression analyses, lower levels of TSAT (hazard ratio [HR] per 1 standard deviation [SD], 0.84; 95% confidence interval [CI], 0.75-0.95; P = 0.004) and higher levels of sTfR (HR, 1.15; 95% CI 1.03-1.28; P = 0.01), EPO (HR, 1.17; 95% CI 1.05-1.29; P = 0.004), and FGF23 (HR, 1.20; 95% CI 1.10-1.32; P < 0.001) were each significantly associated with an increased risk of death, independent of potential confounders. Adjustment for FGF23 levels markedly attenuated the associations of TSAT (HR, 0.89; 95% CI 0.78-1.01; P = 0.06), sTfR (HR, 1.08; 95% CI 0.96-1.20; P = 0.19), and EPO (HR, 1.10; 95% CI 0.99-1.22; P = 0.08) with mortality. FGF23 remained associated with mortality (HR, 1.15; 95% CI 1.04-1.27; P = 0.008) after adjustment for TSAT, sTfR, and EPO levels. Mediation analysis indicated that FGF23 explained 31% of the association between TSAT and mortality; similarly, FGF23 explained 32% of the association between sTfR and mortality and 48% of the association between EPO and mortality (indirect effect P < 0.05 for all analyses). The main limitations of this study were the observational study design and the absence of data on intact FGF23 (iFGF23), precluding us from discerning whether the current results are attributable to an increase in iFGF23 or in C-terminal FGF23 fragments. CONCLUSIONS AND RELEVANCE: In this study, we found that functional iron deficiency and higher EPO levels were each associated with an increased risk of death in the general population. Our findings suggest that FGF23 could be involved in the association between functional iron deficiency and increased EPO levels and death. Investigation of strategies aimed at correcting iron deficiency and reducing FGF23 levels is warranted.

7.
Trials ; 20(1): 295, 2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-31138315

RESUMO

BACKGROUND: Arterial stiffness is closely related to the process of atherosclerosis, an independent cardiovascular risk factor, and predictive of future cardiovascular events and mortality. Recently, we showed that magnesium citrate supplementation results in a clinically relevant improvement of arterial stiffness. It remained unclear whether the observed effect was due to magnesium or citrate, and whether other magnesium compounds may have similar effects. Therefore, we aim to study the long-term effects of magnesium citrate, magnesium oxide and magnesium sulfate on arterial stiffness. In addition, we aim to investigate possible underlying mechanisms, including changes in blood pressure and changes in gut microbiota diversity. METHODS: In this randomized, double-blind, placebo-controlled trial, a total of 162 healthy overweight and slightly obese men and women will be recruited. During a 24-week intervention, individuals will be randomized to receive: magnesium citrate; magnesium oxide; magnesium sulfate (total daily dose of magnesium for each active treatment 450 mg); or placebo. The primary outcome of the study is arterial stiffness measured by the carotid-femoral pulse wave velocity (PWVc-f), which is the gold standard for quantifying arterial stiffness. Secondary outcomes are office blood pressure, measured by a continuous blood pressure monitoring device, and gut microbiota, measured in fecal samples. Measurements will be performed at baseline and at weeks 2, 12 and 24. DISCUSSION: The present study is expected to provide evidence for the effects of different available magnesium formulations (organic and inorganic) on well-established cardiovascular risk markers, including arterial stiffness and blood pressure, as well as on the human gut microbiota. As such, the study may contribute to the primary prevention of cardiovascular disease in slightly obese, but otherwise healthy, individuals. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03632590 . Retrospectively registered on 15 August 2018.

8.
N Engl J Med ; 380(20): 1918-1928, 2019 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-31091373

RESUMO

BACKGROUND: In the context of kidney transplantation, genomic incompatibilities between donor and recipient may lead to allosensitization against new antigens. We hypothesized that recessive inheritance of gene-disrupting variants may represent a risk factor for allograft rejection. METHODS: We performed a two-stage genetic association study of kidney allograft rejection. In the first stage, we performed a recessive association screen of 50 common gene-intersecting deletion polymorphisms in a cohort of kidney transplant recipients. In the second stage, we replicated our findings in three independent cohorts of donor-recipient pairs. We defined genomic collision as a specific donor-recipient genotype combination in which a recipient who was homozygous for a gene-intersecting deletion received a transplant from a nonhomozygous donor. Identification of alloantibodies was performed with the use of protein arrays, enzyme-linked immunosorbent assays, and Western blot analyses. RESULTS: In the discovery cohort, which included 705 recipients, we found a significant association with allograft rejection at the LIMS1 locus represented by rs893403 (hazard ratio with the risk genotype vs. nonrisk genotypes, 1.84; 95% confidence interval [CI], 1.35 to 2.50; P = 9.8×10-5). This effect was replicated under the genomic-collision model in three independent cohorts involving a total of 2004 donor-recipient pairs (hazard ratio, 1.55; 95% CI, 1.25 to 1.93; P = 6.5×10-5). In the combined analysis (discovery cohort plus replication cohorts), the risk genotype was associated with a higher risk of rejection than the nonrisk genotype (hazard ratio, 1.63; 95% CI, 1.37 to 1.95; P = 4.7×10-8). We identified a specific antibody response against LIMS1, a kidney-expressed protein encoded within the collision locus. The response involved predominantly IgG2 and IgG3 antibody subclasses. CONCLUSIONS: We found that the LIMS1 locus appeared to encode a minor histocompatibility antigen. Genomic collision at this locus was associated with rejection of the kidney allograft and with production of anti-LIMS1 IgG2 and IgG3. (Funded by the Columbia University Transplant Center and others.).


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Variações do Número de Cópias de DNA , Rejeição de Enxerto/genética , Transplante de Rim , Proteínas com Domínio LIM/genética , Proteínas Adaptadoras de Transdução de Sinal/imunologia , Estudos de Coortes , Estudos de Associação Genética , Genótipo , Antígenos HLA/genética , Teste de Histocompatibilidade , Humanos , Imunoglobulina G/sangue , Proteínas com Domínio LIM/imunologia , Proteínas de Membrana/genética , Proteínas de Membrana/imunologia , Polimorfismo de Nucleotídeo Único , Doadores de Tecidos
9.
Curr Opin Nephrol Hypertens ; 28(4): 321-327, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30958403

RESUMO

PURPOSE OF REVIEW: Sodium glucose cotransporter 2 (SGLT2) inhibitors are relatively novel antidiabetic drugs that improve glycemic control and reduce cardiovascular outcomes as well as renal function decline. SGLT2 inhibitors act by inhibiting glucose reabsorption in the proximal tubule of the kidney. Emerging data suggest that these drugs may also influence bone and mineral metabolism. This review summarizes clinical trial data on bone and mineral outcomes, and discusses potential underlying mechanisms. RECENT FINDINGS: Three large randomized controlled trials documented cardiovascular and renal protective effects of SGLT2 inhibitors. Recent studies indicate that SGLT2 inhibitors influence renal phosphate reabsorption and calciuria. Although the CANVAS trial suggested an increased fracture risk associated with canagliflozin compared with placebo, the vast majority of trials and meta-analyses did not demonstrate an increased fracture risk associated with SGLT2 inhibitor use. SUMMARY: SGLT2 inhibitors have shown clinically relevant cardiovascular and renal protective effects. The long-term implications for bone health, in particular in the context of chronic kidney disease, are still incompletely understood and warrant further investigation.

11.
Amino Acids ; 51(6): 913-927, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30915571

RESUMO

Cardiovascular disease (CVD) is the leading cause of death in renal transplant recipients (RTR). Elevated plasma asymmetric dimethylarginine (pADMA), an endogenous nitric oxide synthase inhibitor produced from the turnover of methylated arginine moieties in proteins, is a risk factor for CVD and mortality. It is unknown how urinary ADMA excretion (uADMA), one of the main ADMA elimination routes, is associated with long-term survival. Furthermore, the association of pADMA and uADMA with markers for turnover of arginine-methylated proteins is unknown. We analyzed ADMA using a validated GC-MS/MS method in plasma and 24-h urine samples of 685 RTR, included ≥ 1 year after transplantation. We also analyzed urine symmetric dimethylarginine (uSDMA) using the same method. Urinary creatinine and urea excretions were used as markers for turnover of muscle protein and amino acids, respectively. We applied Cox regression analyses to study associations of pADMA, uADMA, and uSDMA with all-cause and CVD mortality. Mean pADMA was 0.61 ± 0.12 µM, uADMA was 31 ± 13 µmol/24 h, and uSDMA was 52 ± 19 µmol/24 h. Over median follow-up of 5.4 [4.9-6.1] years, 147 RTR died, of which 58 (39%) from CVD. High pADMA was associated with high all-cause mortality (HR per SD [95% CI]: 1.45 [1.26-1.67], P < 0.001), while high uADMA was associated with low all-cause and CVD mortality (HR per SD [95% CI]: 0.57 [0.47-0.69], P < 0.001, and 0.55 [0.40-0.74], P < 0.001, respectively). The associations were independent of adjustment for potential confounders. Creatinine excretion was associated with both pADMA (st. ß:- 0.21, P = 0.003) and uADMA (st. ß: 0.49, P < 0.001), and urea excretion was associated with uADMA (st. ß: 0.56, P < 0.001). Associations of uSDMA with outcomes and with creatinine excretion and urea excretion were comparable to those of uADMA. The associations of pADMA, uADMA and uSDMA with mortality were strongly affected by adjustment for creatinine excretion and urea excretion. We found for the first time that high uADMA and high uSDMA are associated with less risk of all-cause and CVD mortality. The links of uADMA and uSDMA with markers of muscle protein and amino acid turnover may serve to further understand ADMA and SDMA homeostasis and their clinical implications.

12.
Am J Transplant ; 19(8): 2262-2273, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30920136

RESUMO

Genetic variation across the human leukocyte antigen loci is known to influence renal-transplant outcome. However, the impact of genetic variation beyond the human leukocyte antigen loci is less clear. We tested the association of common genetic variation and clinical characteristics, from both the donor and recipient, with posttransplant eGFR at different time-points, out to 5 years posttransplantation. We conducted GWAS meta-analyses across 10 844 donors and recipients from five European ancestry cohorts. We also analyzed the impact of polygenic risk scores (PRS), calculated using genetic variants associated with nontransplant eGFR, on posttransplant eGFR. PRS calculated using the recipient genotype alone, as well as combined donor and recipient genotypes were significantly associated with eGFR at 1-year posttransplant. Thirty-two percent of the variability in eGFR at 1-year posttransplant was explained by our model containing clinical covariates (including weights for death/graft-failure), principal components and combined donor-recipient PRS, with 0.3% contributed by the PRS. No individual genetic variant was significantly associated with eGFR posttransplant in the GWAS. This is the first study to examine PRS, composed of variants that impact kidney function in the general population, in a posttransplant context. Despite PRS being a significant predictor of eGFR posttransplant, the effect size of common genetic factors is limited compared to clinical variables.

13.
Nutrients ; 11(3)2019 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-30917546

RESUMO

Non-alcoholic fatty liver disease (NAFLD) is likely to be associated with elevated plasma branched-chain amino acids (BCAAs) and may precede the development of type 2 diabetes (T2D). We hypothesized that BCAAs may be involved in the pathogenesis of T2D attributable to NAFLD and determined the extent to which plasma BCAAs influence T2D development in NAFLD. We evaluated cross-sectional associations of NAFLD with fasting plasma BCAAs (nuclear magnetic resonance spectroscopy), and prospectively determined the extent to which the influence of NAFLD on incident T2D is attributable to BCAA elevations. In the current study, 5791 Prevention of REnal and Vascular ENd-stage Disease (PREVEND) cohort participants without T2D at baseline were included. Elevated fatty liver index (FLI) ≥60, an algorithm based on triglycerides, gamma-glutamyltransferase, body mass index (BMI) and waist circumference, was used as proxy of NAFLD. Elevated FLI ≥ 60 was present in 1671 (28.9%) participants. Cross-sectionally, BCAAs were positively associated with FLI ≥ 60 (ß = 0.208, p < 0.001). During a median follow-up of 7.3 years, 276 participants developed T2D, of which 194 (70.2%) had an FLI ≥ 60 (log-rank test, p < 0.001). Cox regression analyses revealed that both FLI ≥60 (hazard ratio (HR) 3.46, 95% CI 2.45⁻4.87, p < 0.001) and higher BCAA levels (HR 1.19, 95% CI 1.03⁻1.37, p = 0.01) were positively associated with incident T2D. Mediation analysis showed that the association of FLI with incident T2D was in part attributable to elevated BCAAs (proportion mediated 19.6%). In conclusion, both elevated FLI and elevated plasma BCAA levels are associated with risk of incident T2D. The association of NAFLD with T2D development seems partly mediated by elevated BCAAs.


Assuntos
Aminoácidos de Cadeia Ramificada/sangue , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/etiologia , Hepatopatia Gordurosa não Alcoólica/sangue , Hepatopatia Gordurosa não Alcoólica/complicações , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco
14.
World J Surg ; 43(8): 1972-1980, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30798418

RESUMO

BACKGROUND: Parathyroidectomy (PTx) is the treatment of choice for end-stage renal disease (ESRD) patients with therapy-resistant hyperparathyroidism (HPT). The optimal timing of PTx for ESRD-related HPT-before or after kidney transplantation (KTx)-is subject of debate. METHODS: Patients with ESRD-related HPT who underwent both PTx and KTx between 1994 and 2015 were included in a multicenter retrospective study in four university hospitals. Two groups were formed according to treatment sequence: PTx before KTx (PTxKTx) and PTx after KTx (KTxPTx). Primary endpoint was renal function (eGFR, CKD-EPI) between both groups at several time points post-transplantation. Correlation between the timing of PTx and KTx and the course of eGFR was assessed using generalized estimating equations (GEE). RESULTS: The PTxKTx group consisted of 102 (55.1%) and the KTxPTx group of 83 (44.9%) patients. Recipient age, donor type, PTx type, and pre-KTx PTH levels were significantly different between groups. At 5 years after transplantation, eGFR was similar in the PTxKTx group (eGFR 44.5 ± 4.0 ml/min/1.73 m2) and KTxPTx group (40.0 ± 6.4 ml/min/1.73 m2, p = 0.43). The unadjusted GEE model showed that timing of PTx was not correlated with graft function over time (mean difference -1.0 ml/min/1.73 m2, 95% confidence interval -8.4 to 6.4, p = 0.79). Adjustment for potential confounders including recipient age and sex, various donor characteristics, PTx type, and PTH levels did not materially influence the results. CONCLUSIONS: In this multicenter cohort study, timing of PTx before or after KTx does not independently impact graft function over time.

15.
Am J Nephrol ; 49(3): 193-202, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30808845

RESUMO

BACKGROUND: Serum urea level is a heritable trait, commonly used as a diagnostic marker for kidney function. Genome-wide association studies (GWAS) in East-Asian populations identified a number of genetic loci related to serum urea, however there is a paucity of data for European populations. METHODS: We performed a two-stage meta-analysis of GWASs on serum urea in 13,312 participants, with independent replication in 7,379 participants of European ancestry. RESULTS: We identified 6 genome-wide significant single nucleotide polymorphisms (SNPs) in or near 6 loci, of which 2 were novel (POU2AF1 and ADAMTS9-AS2). Replication of East-Asian and Scottish data provided evidence for an additional 8 loci. SNPs tag regions previously associated with anthropometric traits, serum magnesium, and urinary albumin-to-creatinine ratio, as well as expression quantitative trait loci for genes preferentially expressed in kidney and gastro-intestinal tissues. CONCLUSIONS: Our findings provide insights into the genetic underpinnings of urea metabolism, with potential relevance to kidney function.

16.
Artigo em Inglês | MEDLINE | ID: mdl-30753729

RESUMO

Background: Kidney transplant recipients (KTRs) experience substantial survival benefit compared with dialysis patients. However, their mortality and graft failure risk remain high. KTRs are often low in micronutrient status, including vitamins D and K. We investigated the association of both vitamins D and K status, and vitamin D treatment with all-cause mortality and death-censored graft failure. Methods: We studied 461 KTRs from a single-centre study at median 6.1 years after transplantation. At baseline, vitamins D and K concentrations were measured by 25-hydroxyvitamin D [25(OH)D] and dephosphorylated uncarboxylated matrix gla protein (dp-ucMGP) and patients were categorized into: 25(OH)D <50/≥50 nmol/L and median dp-ucMGP <1057/≥1057 pmol/L. Results: Mean age was 52 ± 12 years, and 122 KTRs (26%) had low vitamins D and K status. During median 9.8 years follow-up, 128 patients (28%) died and 48 (10%) developed death-censored graft failure. Low vitamins D and K status was associated with 2.33 (1.26-4.30) [hazard ratio (95% confidence interval)] increased mortality risk and 3.25 (1.17-9.08) increased graft failure risk compared with KTR with 25(OH)D ≥50 nmol/L and dp-ucMGP <1057 pmol/L. Dp-ucMGP was strongly associated with mortality (per 500 pmol/L increase): 1.41 (1.08-1.41) for vitamin D treatment versus no treatment 1.07 (0.97-1.18), and graft failure 1.71 (1.17-2.49) for vitamin D treatment versus 1.19 (1.05-1.36) no treatment, P-interaction <0.07 for vitamin D treatment (n = 44). Conclusions: Combined vitamins D and K deficiency are highly prevalent and are associated with increased mortality and graft failure risk compared with high vitamins D and K status. Low vitamin K status was strongly associated with an increased risk of premature mortality and graft failure for patients treated with vitamin D versus no vitamin D treatment.

17.
Nat Commun ; 10(1): 29, 2019 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-30604766

RESUMO

Chronic kidney disease (CKD) affects ~10% of the global population, with considerable ethnic differences in prevalence and aetiology. We assemble genome-wide association studies of estimated glomerular filtration rate (eGFR), a measure of kidney function that defines CKD, in 312,468 individuals of diverse ancestry. We identify 127 distinct association signals with homogeneous effects on eGFR across ancestries and enrichment in genomic annotations including kidney-specific histone modifications. Fine-mapping reveals 40 high-confidence variants driving eGFR associations and highlights putative causal genes with cell-type specific expression in glomerulus, and in proximal and distal nephron. Mendelian randomisation supports causal effects of eGFR on overall and cause-specific CKD, kidney stone formation, diastolic blood pressure and hypertension. These results define novel molecular mechanisms and putative causal genes for eGFR, offering insight into clinical outcomes and routes to CKD treatment development.


Assuntos
Taxa de Filtração Glomerular/genética , Hipertensão/genética , Cálculos Renais/genética , Rim/fisiopatologia , Insuficiência Renal Crônica/genética , Adulto , Idoso , Pressão Sanguínea/genética , Grupos Étnicos/genética , Feminino , Loci Gênicos/genética , Estudo de Associação Genômica Ampla , Código das Histonas/genética , Histonas/metabolismo , Humanos , Hipertensão/etnologia , Hipertensão/fisiopatologia , Cálculos Renais/etnologia , Cálculos Renais/fisiopatologia , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Insuficiência Renal Crônica/etnologia , Insuficiência Renal Crônica/fisiopatologia
18.
Amino Acids ; 51(3): 565-575, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30610470

RESUMO

Asymmetric dimethylarginine (ADMA) is a methylated form of arginine and an endogenous nitric oxide synthase inhibitor. Renal function decline is associated with increase of plasma ADMA in chronic kidney disease populations. It is yet unknown how isolated renal function impairment affects ADMA homeostasis in healthy humans. Here, we measured plasma concentrations and urinary excretion of ADMA using GC-MS/MS in 130 living kidney donors before and at 1.6 (1.6-1.9) months after donation. We additionally analyzed 201 stable renal transplant recipients (RTR) that were included > 1 year after transplantation, as a model for kidney disease in the context of single kidney state. We measured true glomerular filtration rate (mGFR) using 125I-iothalamate. To study enzymatic metabolism of ADMA, we also measured L-citrulline as primary metabolite. Mean age was 52 ± 10 years in donors and 54 ± 12 years in RTR. Renal function was significantly reduced from pre- to post-donation (mGFR: 104 ± 17 vs. 66 ± 10 ml/min per 1.73 m2 BSA, - 36 ± 7%, P < 0.001). Urinary ADMA excretion strongly and significantly decreased from pre- to post-donation (60.6 ± 16.0 vs. 40.5 ± 11.5 µmol/24 h, - 31.5 ± 21.5%, P < 0.001), while plasma ADMA increased only slightly (0.53 ± 0.08 vs. 0.58 ± 0.09 µM, 11.1 ± 20.1%, P < 0.001). Compared to donors post-donation, RTR had significantly worse renal function (mGFR: 49 ± 18 ml/min/1.73 m2, - 25 ± 2%, P < 0.001) and lower urinary ADMA excretion (30.9 ± 12.4 µmol/24 h, - 23.9 ± 3.4%, P < 0.001). Plasma ADMA in RTR (0.60 ± 0.11 µM) did not significantly differ from donors post-donation (2.9 ± 1.9%, P = 0.13). Plasma citrulline was inversely associated with mGFR (st. ß: - 0.23, P < 0.001), consistent with increased ADMA metabolism to citrulline with lower GFR. In both groups, the response of urinary ADMA excretion to renal function loss was much larger than that of plasma ADMA. As citrulline was associated with GFR, our data indicate that with renal function impairment, a decrease in urinary ADMA excretion does not lead to a corresponding increase in plasma ADMA, likely due to enhanced metabolism, thus allowing for lower renal excretion of ADMA.


Assuntos
Arginina/análogos & derivados , Citrulina/sangue , Homeostase , Nefropatias/fisiopatologia , Transplante de Rim , Doadores Vivos , Transplantados , Arginina/sangue , Arginina/urina , Estudos de Casos e Controles , Feminino , Taxa de Filtração Glomerular , Humanos , Nefropatias/metabolismo , Testes de Função Renal , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Espectrometria de Massas em Tandem
20.
Clin J Am Soc Nephrol ; 14(1): 66-73, 2019 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-30559106

RESUMO

BACKGROUND AND OBJECTIVES: The sodium glucose cotransporter 2 (SGLT-2) inhibitor dapagliflozin is a novel drug for the treatment of diabetes mellitus. Recent studies suggest that SGLT-2 inhibitors affect phosphate homeostasis, but their effects on phosphate-regulating hormones in patients with diabetic kidney disease are still unclear. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We performed a post-hoc analysis of a double-blind, randomized, crossover trial in patients with type 2 diabetes with early-stage diabetic kidney disease on stable renin-angiotensin-aldosterone system blockade, with an albumin-to-creatinine ratio between 100 and 3500 mg/g, eGFR≥45 ml/min per 1.73 m2, and glycosylated hemoglobin≥7.2% and <11.4%. Patients were randomized to dapagliflozin 10 mg/d or placebo during consecutive 6-week study periods, separated by a 6-week wash-out. We investigated effects on circulating phosphate, calcium, parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), 25-hydroxyvitamin D (25[OH]D), and 1,25-dihydroxyvitamin D (1,25[OH]2D) levels. RESULTS: Thirty-one patients (age 62 years; 23% female) were analyzed. Compared with placebo, dapagliflozin increased serum phosphate by 9% (95% confidence interval, 4% to 15%; P=0.002), PTH increased by 16% (3% to 30%; P=0.01), FGF23 increased by 19% (0.3% to 42%; P=0.05), and serum 1,25(OH)2D decreased by -12% (-25% to 4%; P=0.12). Calcium and 25(OH)D were unaffected. We found no correlation between changes in markers of phosphate homeostasis and changes in eGFR or 24-hour albumin excretion during dapagliflozin treatment. CONCLUSIONS: Dapagliflozin increases serum phosphate, plasma PTH, and FGF23. This effect was independent of concomitant changes in eGFR or 24-hour albumin excretion.

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