Blood pressure, proteinuria, and phosphate as risk factors for progressive kidney disease: a hypothesis

Assessment of atherosclerosis and endothelial dysfunction risk factors in patients with primary glomerulonephritis

INTRODUCTION

Glomerulonephritis are the third cause of chronic kidney disease (CKD) requiring dialysis in Brazil. Mineral and bone disorder (MBD) is one of the complications of CKD and is already present in the early stages. Assessment of carotid intima-media thickness (CIMT) and flow-mediated vasodilatation (FMV) are non-invasive ways of assessing cardiovascular risk.

HYPOTHESIS

Patients with primary glomerulonephritis (PG) have high prevalence of atherosclerosis and endothelial dysfunction, not fully explained by traditional risk factors, but probably influenced by the early onset of MBD.

OBJECTIVE

To evaluate the main markers of atherosclerosis in patients with PG.

METHOD

Clinical, observational, cross-sectional and controlled study. Patients with PG were included and those under 18 years of age, pregnants, those with less than three months of follow-up and those with secondary glomerulonephritis were excluded. Those who, at the time of exams collection, had proteinuria higher than 6 grams/24 hours and using prednisone at doses higher than 0.2 mg/kg/day were also excluded.

RESULTS

95 patients were included, 88 collected the exams, 1 was excluded and 23 did not undergo the ultrasound scan. Patients with PG had a higher mean CIMT compared to controls (0.66 versus 0.60), p = 0.003. After multivariate analysis, age and values for systolic blood pressure (SBP), FMV and GFR (p = 0.02); and FMV and serum uric acid (p = 0.048) remained statistically relevant.

DISCUSSION AND CONCLUSION

The higher cardiovascular risk in patients with PG was not explained by early MBD. Randomized and multicentric clinical studies are necessary to better assess this hypothesis.

Avaliação dos fatores de risco de aterosclerose e disfunção endotelial em pacientes com glomerulopatias primárias

Resumo Introdução: Glomerulopatias são a terceira causa de doença renal crônica (DRC) com necessidade de diálise no Brasil. Distúrbio mineral e ósseo (DMO) é uma das complicações da DRC e está presente já nos estágios iniciais. A avaliação da espessura médio-intimal de carótidas (EMIC) e da vasodilatação fluxo-mediada (VFM) são maneiras não invasivas de avaliação do risco cardiovascular. Hipótese: Pacientes com glomerulopatias primárias (GP) apresentam alta prevalência de aterosclerose e disfunção endotelial, não explicada totalmente pelos fatores de risco tradicionais, mas provavelmente influenciada pela instalação precoce do DMO. Objetivo: Avaliar os principais marcadores de aterosclerose em pacientes com GP. Método: Estudo clínico, observacional, transversal e controlado. Foram incluídos portadores de GP e excluídos menores de 18 anos, gestantes, menos de três meses de seguimento e os com glomerulopatia secundária. Também foram excluídos aqueles que, no momento da coleta, apresentavam proteinúria maior que 6 gramas/24 horas e uso de prednisona em doses superiores a 0,2 mg/kg/dia. Resultados: 95 pacientes foram incluídos, 88 colheram os exames, 1 foi excluído e 23 não realizaram a ultrassonografia. Os pacientes com GP apresentaram maior EMIC média em relação ao controle (0,66 versus 0,60), p = 0,003. Após análise multivariada, mantiveram relevância estatística a idade e os valores de pressão arterial sistólica (PAS), VFM e TFG (p = 0,02) e VFM e ácido úrico sérico (p = 0,048). Discussão e conclusão: Pacientes com GP apresentaram maior risco cardiovascular, entretanto esse risco não foi explicitado pelo DMO precoce. Estudos clínicos randomizados e multicêntricos são necessários para melhor determinação dessa hipótese.

Diastolic Pressure and ACR Are Modifiable Risk Factors of Arterial Stiffness in T2DM Without Cardiovascular Disease

AIM

To evaluate early, before the onset of cardiovascular events and of chronic renal insufficiency, the association between chronic kidney disease (CKD)-mineral bone disorder (MBD) biomarkers and vascular stiffness [Cardio Ankle Vascular Index (CAVI)] in the course of type 2 diabetes (T2DM).

METHOD

We evaluated 174 T2DM patients [median age 56 years; male/female (M/F) 100/74] with diabetes duration < 10 years and without decreased estimated glomerular filtration rate (eGFR; ≥60 mL/min/1.73 m2) or macrovascular complications. Thirty-four age-matched healthy subjects [M/F 13/21; age 53.5 (50.0-57.7) years; eGFR 107.5 (97.0-119.7) mL/ min1.73 m2] served as local reference control for CAVI (pathological: ≥8) and the novel CKD-MBD biomarkers.

RESULTS

Albumin-to-creatinine ratio (ACR) averaged 8.5 mg/g (5.6-17.2) with 12.6% of the patients showing pathologic values, indicative of incipient diabetic nephropathy. Serum parathyroid hormone, fibroblast growth factor 23, and sclerostin were higher while 1,25-dihydroxyvitamin D and Klotho were lower than a control group. CAVI was normal (<8) in only 54% and correlated positively with age (P < 0.001), hemoglobin 1A1c (P = 0.036), and systolic (P = 0.021) and diastolic blood pressure (DBP) (P = 0.001) and negatively correlated with 25-hydroxyvitamin D (P = 0.046). In multivariate analysis, age, DBP, ACR, and serum Klotho were independent positive predictors of CAVI.

CONCLUSION

In the absence of overt cardiovascular disease and of chronic renal insufficiency, CAVI is frequently pathologic in T2DM. DBP and ACR are modifiable risk factors of vascular stiffness in T2DM, thus warranting optimal assessment.

Crosstalk between bone and other organs

Bone has long been considered as a silent organ that provides a reservoir of calcium and phosphorus, traditionally. Recently, further study of bone has revealed additional functions as an endocrine organ connecting systemic organs of the whole body. Communication between bone and other organs participates in most physiological and pathological events and is responsible for the maintenance of homeostasis. Here, we present an overview of the crosstalk between bone and other organs. Furthermore, we describe the factors mediating the crosstalk and review the mechanisms in the development of potential associated diseases. These connections shed new light on the pathogenesis of systemic diseases and provide novel potential targets for the treatment of systemic diseases.

Focus on the Possible Role of Dietary Sodium, Potassium, Phosphate, Magnesium, and Calcium on CKD Progression

The impressive estimated number of chronic kidney disease (CKD) patients in the world justifies any possible effort at implementing preventive measures of disease progression. Renal insufficiency is associated with significant changes in the electrolyte handling and body balance of sodium, potassium, phosphate, magnesium, and calcium, all of which are biologically vital molecules. Dietary habits could contribute significantly to the optimal management of possible derangements. In this review, we examined the available evidence recommending dietary prescriptions for these five elements aiming at reducing CKD progression. Clear evidence that specific dietary prescriptions may halt or reduce CKD progression is lacking. However, some practical recommendations are possible to prescribe the best possible therapy to the individual CKD patient.

Association of Mineral Bone Disorder With Decline in Residual Kidney Function in Incident Hemodialysis Patients

Abnormalities of mineral bone disorder (MBD) parameters have been suggested to be associated with poor renal outcome in predialysis patients. However, the impact of those parameters on decline in residual kidney function (RKF) is uncertain among incident hemodialysis (HD) patients. We performed a retrospective cohort study in 13,772 patients who initiated conventional HD during 2007 to 2011 and survived 6 months of dialysis. We examined the association of baseline serum phosphorus, calcium, intact parathyroid hormone (PTH), and alkaline phosphatase (ALP) with a decline in RKF. Decline in RKF was assessed by estimated slope of renal urea clearance (KRU) over 6 months from HD initiation. Our cohort had a mean ± SD age of 62 ± 15 years; 64% were men, 57% were white, 65% had diabetes, and 51% had hypertension. The median (interquartile range [IQR]) baseline KRU level was 3.4 (2.0, 5.2) mL/min/1.73 m² . The median (IQR) estimated 6-month KRU slope was -1.47 (-2.24, -0.63) mL/min/1.73 m² per 6 months. In linear regression models, higher phosphorus categories were associated with a steeper 6-month KRU slope compared with the reference category (phosphorus 4.0 to <4.5 mg/dL). Lower calcium and higher intact PTH and ALP categories were also associated with a steeper 6-month KRU slope compared with their respective reference groups (calcium 9.2 to <9.5 mg/dL; intact PTH 150 to <250 pg/mL; ALP <60 U/L). The increased number of parameter abnormalities had an additive effect on decline in RKF. Abnormalities of MBD parameters including higher phosphorus, intact PTH, ALP and lower calcium levels were independently associated with decline in RKF in incident HD patients. © 2019 American Society for Bone and Mineral Research. © 2019 American Society for Bone and Mineral Research.

Antiproteinuria Effect of Calcitriol in Patients With Chronic Kidney Disease and Vitamin D Deficiency: A Randomized Controlled Study

OBJECTIVE

Vitamin D has been demonstrated to lessen proteinuria severity in chronic kidney disease (CKD). Compared with healthy populations, patients with CKD may have lower serum levels of 1,25-dihydroxy vitamin D (1,25-(OH)2 D) and 25-hydroxy vitamin D (25-(OH) D). We investigated the effect of  oral low-dose active vitamin D (calcitriol at 0.25 μg, 3 times weekly) on urinary protein excretion.

DESIGN AND METHODS

We conducted a nonblinded and non-placebo-controlled study. In total, 60 patients with CKD (average estimated glomerular filtration rate of >15 mL/min) who received a stable dose of angiotensin receptor blocker (ARB) or angiotensin-converting enzyme inhibitor (ACEI) were enrolled in this 24-week study. We randomly assigned these patients to the vitamin D group (oral calcitriol at 0.25 μg 3 times weekly with an ACEI or ARB) or the control group (ACEI or ARB). Change in the urine protein/creatinine ratio (uPCR) was the primary endpoint in this study.

RESULTS

The mean baseline uPCRs of the 2 groups were comparable (1.84 ± 0.83 g/g vs. 2.02 ± 0.97 g/g, control vs. vitamin D group; P = .46). After the 24-week treatment, the uPCRs were significantly lower than the baseline values in the vitamin D group (1.35 ± 0.64 g/g; P < .05) but not in the control group. The values of uPCR decreased significantly at 8, 16, and 24 weeks (P < .05 vs. baseline) in the vitamin D group. The values of uPCRs were significantly lower in the vitamin D group than in the control group at 8, 16, and 24 weeks (P < .05). A positive correlation was discovered between reduction in uPCRs at 24-week and baseline 25-(OH) D serum level in the vitamin D group (r = 0.738, P < .001).

CONCLUSION

Supplementary low-dose active vitamin D could reduce proteinuria in CKD patients with low serum 25-(OH) D levels.

Bone, inflammation and the bone marrow niche in chronic kidney disease: what do we know?

Recent improvements in our understanding of physiology have altered the way in which bone is perceived: no longer is it considered as simply the repository of divalent ions, but rather as a sophisticated endocrine organ with potential extraskeletal effects. Indeed, a number of pathologic conditions involving bone in different ways can now be reconsidered from a bone-centred perspective. For example, in metabolic bone diseases like osteoporosis (OP) and renal osteodystrophy (ROD), the association with a worse cardiovascular outcome can be tentatively explained by the possible derangements of three recently discovered bone hormones (osteocalcin, fibroblast growth factor 23 and sclerostin) and a bone-specific enzyme (alkaline phosphatase). Further, in recent years the close link between bone and inflammation has been better appreciated and a wide range of chronic inflammatory states (from rheumatoid arthritis to ageing) are being explored to discover the biochemical changes that ultimately lead to bone loss and OP. Also, it has been acknowledged that the concept of the bone-vascular axis may explain, for example, the relationship between bone metabolism and vessel wall diseases like atherosclerosis and arteriosclerosis, with potential involvement of a number of cytokines and metabolic pathways. A very important discovery in bone physiology is the bone marrow (BM) niche, the functional unit where stem cells interact, exchanging signals that impact on their fate as bone-forming cells or immune-competent haematopoietic elements. This new element of bone physiology has been recognized to be dysfunctional in diabetes (so-called diabetic mobilopathy), with possible clinical implications. In our opinion, ROD, the metabolic bone disease of renal patients, will in the future probably be identified as a cause of BM niche dysfunction. An integrated view of bone, which includes the BM niche, now seems necessary in order to understand the complex clinical entity of chronic kidney disease-mineral and bone disorders and its cardiovascular burden. Bone is thus becoming a recurrently considered paradigm for different inter-organ communications that needs to be considered in patients with complex diseases.

Small steps towards the potential of 'preventive' treatment of early phosphate loading in chronic kidney disease patients

Few clinical studies have investigated the value of phosphate (P)-lowering therapies in early chronic kidney disease (CKD) patients in whom hyperphosphataemia has not yet clearly developed and they report conflicting and even unexpected results. In this issue of Clinical Kidney Journal, de Krijger et al. found that sevelamer carbonate (4.8 g/day for 8 weeks) did not induce a significant reduction of pulse wave velocity (PWV) and that fibroblast growth factor 23 (FGF23) did not decrease despite a decline in 24-h urine P excretion. To some extent these findings challenge the concept that 'preventive' P binder therapy to lower FGF23 is a useful approach, at least over this short period of time. Interestingly, in a subgroup of patients with absent or limited abdominal vascular calcification, treatment did result in a statistically significant reduction in adjusted PWV, suggesting that PWV is amenable to improvement in this subset. Interpretation of the scarce and heterogeneous observations described in early CKD remains difficult and causality and/or the possibility of 'preventive' treatment may not yet be completely disregarded. Moreover, de Krijger et al. contribute to the identification of new sources of bias and methodological issues that may lead to more personalized treatments, always bearing in mind that not all patients and not all P binders are equal.

Role of sodium/glucose cotransporter inhibition on a rat model of angiotensin II-dependent kidney damage

Background

Renal proximal tubular sodium and glucose reabsorption are regulated by the sodium-glucose cotransporter (SGLT2). Changes in this transporter can play a role in hyperglycaemia and reactive oxygen species (ROS) production. We demonstrated increased glucose absorption in proximal tubule membrane vesicles and increased expression of SGLT2 in hypertensive rats. Here we investigated Angiotensin II (Ang II) -dependent SGLT2 expression induction and the role of SGLT2 induction in the development of Ang II-dependent kidney damage. The aim of this study was to determine whether SGLT2 induction by Ang II is associated with Ang II-dependent kidney damage. We propose the following objectives a) to demonstrate that Ang II induces SGLT2 expression and b) to demonstrate that prevention of SGLT2 expression and activity prevent Ang II-induced kidney damage.

Methods

We used chronic Ang II infusion as a model of kidney damage in male Wistar rats and evaluated systolic blood pressure by telemetric methods. SGLT2 mRNA and protein expression were evaluated by PCR and immunoblotting. SGLT2 activity was evaluated in brush border membrane vesicles by measuring glucose uptake. ROS production was measured by confocal microscopy. The glomerular filtration rate (GFR) was evaluated by the inulin excretion method, and urinary protein excretion was evaluated by the Bradford method. Biological parameter evaluations were performed, after two weeks of infusion of Ang II. We compared the effects of Angiotensin II (AT1) receptor blockade by Losartan and SGLT2 inhibition by Empagliflozin both as monotherapy treatments and in combination on the development of kidney damage.

Results

Chronic Ang II infusion led to a blood pressure elevation and increased SGLT2 mRNA expression and activity as well as kidney damage, as reflected by increased ROS production, decreased GFR and increased urinary protein excretion. AT1 receptor blockade prevented all these changes. By contrast, SGLT2 inhibition did not affect blood pressure and had a small effect on kidney damage. However, the combination of both drugs resulted in the potentiation of the effects observed by AT1 receptor blockade alone.

Conclusions

We suggest that Ang II-dependent increased SGLT2 induction is one mechanism by which Ang II induces kidney damage.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1490-z) contains supplementary material, which is available to authorized users.

Discovery of endoplasmic reticulum calcium stabilizers to rescue ER-stressed podocytes in nephrotic syndrome

Emerging evidence has established primary nephrotic syndrome (NS), including focal segmental glomerulosclerosis (FSGS), as a primary podocytopathy. Despite the underlying importance of podocyte endoplasmic reticulum (ER) stress in the pathogenesis of NS, no treatment currently targets the podocyte ER. In our monogenic podocyte ER stress-induced NS/FSGS mouse model, the podocyte type 2 ryanodine receptor (RyR2)/calcium release channel on the ER was phosphorylated, resulting in ER calcium leak and cytosolic calcium elevation. The altered intracellular calcium homeostasis led to activation of calcium-dependent cytosolic protease calpain 2 and cleavage of its important downstream substrates, including the apoptotic molecule procaspase 12 and podocyte cytoskeletal protein talin 1. Importantly, a chemical compound, K201, can block RyR2-Ser2808 phosphorylation-mediated ER calcium depletion and podocyte injury in ER-stressed podocytes, as well as inhibit albuminuria in our NS model. In addition, we discovered that mesencephalic astrocyte-derived neurotrophic factor (MANF) can revert defective RyR2-induced ER calcium leak, a bioactivity for this ER stress-responsive protein. Thus, podocyte RyR2 remodeling contributes to ER stress-induced podocyte injury. K201 and MANF could be promising therapies for the treatment of podocyte ER stress-induced NS/FSGS.

Effects of Sevelamer Carbonate in Patients With CKD and Proteinuria: The ANSWER Randomized Trial

RATIONALE & OBJECTIVE

Hyperphosphatemia is associated with increased risk for chronic kidney disease (CKD) progression and reduced antiproteinuric effects of renin-angiotensin system (RAS) blockers. We investigated whether the phosphate binder sevelamer carbonate may enhance the antiproteinuric effect of RAS inhibitors in patients with CKD.

STUDY DESIGN

Phase 2, randomized, controlled, open-label, crossover trial.

SETTING & PARTICIPANTS

Between November 2013 and December 2014, we enrolled 53 patients with CKD with estimated glomerular filtration rates (eGFRs)>15mL/min/1.73m² and residual proteinuria with protein excretion≥0.5g/24h despite maximal tolerated ramipril and/or irbesartan therapy from 2 nephrology units in Italy.

INTERVENTION

After stratification by serum phosphate level, ≤4 or>4mg/dL, patients were randomly assigned to 3 months of sevelamer (1,600mg thrice daily) treatment followed by 3 months without sevelamer separated by a 1-month washout period or 3 months without sevelamer followed by 3 months with sevelamer, also separated by a 1-month washout period.

OUTCOMES

The primary outcome was 24-hour proteinuria (n=49patients). Secondary outcomes included measured GFR (using iohexol plasma clearance), office blood pressure (BP), serum lipid levels, levels of inflammation and bone metabolism biomarkers, urinary electrolyte levels, and arterial stiffness.

RESULTS

Changes in proteinuria during the 3-month treatment with (from 1.36 [IQR, 0.77-2.51] to 1.36 [IQR, 0.77-2.60] g/24h) or without (from 1.36 [IQR, 0.99-2.38] to 1.48 [IQR, 0.81-2.77] g/24h) sevelamer were similar (P=0.1). Sevelamer reduced urinary phosphate excretion without affecting serum phosphate levels. Sevelamer reduced C-reactive protein (CRP), glycated hemoglobin, and total and low-density lipoprotein cholesterol levels and increased high-density lipoprotein cholesterol levels without affecting levels of office BP, measured GFR, fibroblast growth factor 23, klotho, intact parathyroid hormone, serum vitamin D, or other urinary electrolytes. Results were similar in the low- and high-phosphate groups. Sevelamer was well tolerated. Adverse events were comparable between treatment periods. One case of transient hypophosphatemia was observed during treatment with sevelamer.

LIMITATIONS

Short treatment duration, lower pretreatment proteinuria than expected.

CONCLUSIONS

3-month sevelamer treatment did not reduce proteinuria in patients with CKD on maximal RAS blockade. Amelioration of inflammation and dyslipidemia with sevelamer treatment raises the possibility that it may confer benefit in patients with CKD beyond reduction of proteinuria.

FUNDING

Sanofi (Milan, Italy).

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT01968759.

The incessant search for renal biomarkers: is it really justified?

PURPOSE OF REVIEW

This review summarizes the most recent and relevant findings in the search for novel biomarkers for the most common renal diseases.

RECENT FINDINGS

Unprecedented, fast-paced technical advances in biomedical research have offered an opportunity to identify novel and more specific renal biomarkers in several clinical settings. However, despite the huge efforts made, the molecules identified so far have generally failed to provide relevant information beyond what has already been generated by established biomarkers, such as serum creatinine and proteinuria, whereas the complexity and costs of these technology platforms hamper their widespread implementation.

SUMMARY

No novel renal biomarkers have added clear-cut additional value in clinical decision-making. The only exception is anti-phospholipase A2 receptor antibodies, which have been implemented successfully as a diagnostic and prognostic biomarker of membranous nephropathy. This achievement, along with the large number of ongoing collaborative projects worldwide, should lead the renal community to be quite confident regarding the successful qualification of novel and effective diagnostic, prognostic and therapeutic response biomarkers for kidney diseases, hopefully in the next few years.

Folic Acid and Homocysteine in Chronic Kidney Disease and Cardiovascular Disease Progression: Which Comes First?

Background

Hyperhomocysteinemia (Hhcy) occurs in about 85% of chronic kidney disease (CKD) patients because of impaired renal metabolism and reduced renal excretion. Folic acid (FA), the synthetic form of vitamin B₉, is critical in the conversion of homocysteine (Hcy) to methionine. If there is not enough intake of FA, there is not enough conversion, and Hcy levels are raised.

Summary

Hhcy is regarded as an independent predictor of cardiovascular morbidity and mortality in end-stage renal disease. Hhcy exerts its pathogenic action on the main processes involved in the progression of vascular damage. Research has shown Hhcy suggests enhanced risks for inflammation and endothelial injury which lead to cardiovascular disease (CVD), stroke, and CKD. FA has also been shown to improve endothelial function without lowering Hcy, suggesting an alternative explanation for the effect of FA on endothelial function. Recently, the role of FA and Hhcy in CVD and in CKD progression was renewed in some randomized trials.

Key Messages

In the general population and in CKD patients, it remains a topic of discussion whether any beneficial effects of FA therapy are to be referred to its direct effect or to a reduction of Hhcy. While waiting for the results of confirmatory trials, it is reasonable to consider FA with or without methylcobalamin supplementation as appropriate adjunctive therapy in patients with CKD.

Use of Everolimus in Liver Transplantation: Recommendations From a Working Group

Immunosuppression after liver transplantation (LT) is presently based on use of calcineurin inhibitors (CNI), although they are associated with an increased incidence of renal dysfunction, cardiovascular complications, and de novo and recurrent malignancies. Over the past decade, mammalian target of rapamycin inhibitors have received considerable attention as immunosuppressants because they are associated with a more favorable renal profile versus CNI, as well as antiproliferative activity in clinical studies. Comprehensive guidelines on use of everolimus (EVR) in LT are still lacking. In Italy, a project, named Everolimus: the road to long-term functioning, was initiated to collect the experience on EVR after LT with the aim of providing guidance for transplant clinicians. Herein, recommendations by this national consensus group, based on Delphi methodology, are presented. Consensus was reached on 20 of the 23 statements proposed, and their level of evidence, grade of recommendation, and percent of agreement are reported. Statements are grouped into 4 areas: (A) renal function; (B) time of EVR introduction, CNI reduction and elimination, and risk for graft rejection; (C) antiproliferative effects of EVR; and (D) management of EVR-related adverse events. The high level of consensus shows that there is good agreement on the routine use of EVR in predefined clinical scenarios, especially in light of posttransplant nephrotoxicity and other adverse events associated with long-term administration of CNIs.

The authors summarize the recommendations reached by an Italian National Consensus group using the Delphi methodology on the use of everolimus in liver transplantation, particularly its role in renal function, antiproliferative effects, adverse events, timing of introduction, and rejection risk.

Impacts of chronic kidney disease and diabetes on cardiovascular mortality in a general Japanese population: A 20-year follow-up of the NIPPON DATA90 study

Background Studies have shown significant associations of chronic kidney disease (CKD) and diabetes mellitus (DM) with cardiovascular disease (CVD) mortality. The impact on the general population is an important public health issue. However, the population attributable fraction (PAF) of CVD because of CKD and/or DM in a general population is uncertain. Methods We followed 7229 participants (age: ≥30 years) with no history of CVD in a Japanese community. We divided participants into four categories according to CKD and/or DM and calculated hazard ratios (HRs) of CVD mortality for each category using a Cox proportional hazards model adjusted for age, dyslipidemia, smoking and alcohol consumption. In addition, PAFs of CVD were estimated among populations with CKD and/or DM. Results During 20-year follow-up, 488 participants died. HRs for CVD were 1.63 [95% confidence interval (CI): 1.16-2.30] with DM only, 1.42 (95% CI: 1.08-1.86) with CKD only and 2.37 (95% CI: 1.40-4.01) with CKD + DM. In men, the corresponding HRs for CVD were 1.88 (95% CI: 1.19-2.97), 1.71 (95% CI: 1.15-2.56) and 3.26 (95% CI: 1.69-6.30), respectively; the corresponding PAFs of CVD were 4.1%, 5.1% and 2.9%, respectively. PAFs for CVD among women were lower than those in men, 1.6% for DM only, 2.0% for CKD only and 0.7% for CKD + DM. Conclusions PAFs of CVD mortality due to CKD and/or DM were not so high in past 20 years; however, they might increase in the future because of recent increase in prevalence of these in Japanese population.

Plasma Uromodulin Correlates With Kidney Function and Identifies Early Stages in Chronic Kidney Disease Patients

Uromodulin, released from tubular cells of the ascending limb into the blood, may be associated with kidney function. This work studies the relevance of plasma uromodulin as a biomarker for kidney function in an observational cohort of chronic kidney disease (CKD) patients and subjects without CKD (CKD stage 0). It should be further evaluated if uromodulin allows the identification of early CKD stages.Plasma uromodulin, serum creatinine, cystatin C, blood-urea-nitrogen (BUN) concentrations, and estimated glomerular filtration rate (eGFR CKD-EPIcrea-cystatin) were assessed in 426 individuals of whom 71 were CKD stage 0 and 355 had CKD. Besides descriptive statistics, univariate correlations between uromodulin and biomarkers/eGFR were calculated using Pearson-correlation coefficient. Multiple linear regression modeling was applied to establish the association between uromodulin and eGFR adjusted for demographic parameters and pharmacologic treatment. Receiver-operating-characteristic (ROC) analysis adjusted for demographic parameters was performed to test if uromodulin allows differentiation of subjects with CKD stage 0 and CKD stage I.Mean uromodulin plasma levels were 85.7 ± 60.5 ng/mL for all CKD stages combined. Uromodulin was correlated with all biomarkers/eGFR in univariate analysis (eGFR: r = 0.80, creatinine: r = -0.76, BUN: r = -0.72, and cystatin C: r = -0.79). Multiple linear regression modeling showed significant association between uromodulin and eGFR (coefficient estimate β = 0.696, 95% confidence interval [CI] 0.603-0.719, P < 0.001). In ROC analysis uromodulin was the only parameter that significantly improved a model containing demographic parameters to differentiate between CKD 0° and I° (area under the curve [AUC] 0.831, 95% CI 0.746-0.915, P = 0.008) compared to creatinine, cystatin C, BUN, and eGFR (AUC for creatinine: 0.722, P = 0.056, cystatin C: 0.668, P = 0.418, BUN: 0.653, P = 0.811, and eGFR: 0.634, P = 0.823).Plasma uromodulin serves as a robust biomarker for kidney function and uniquely allows the identification of early stages of CKD. As a marker of tubular secretion it might represent remaining nephron mass and therefore intrinsic "kidney function" rather than just glomerular filtration, the latter only being of limited value to represent kidney function as a whole. It therefore gives substantial information on the renal situation in addition to glomerular filtration and potentially solves the problem of creatinine-blind range of CKD, in which kidney impairment often remains undetected.

Predictors of Rapid Progression of Glomerular and Nonglomerular Kidney Disease in Children and Adolescents: The Chronic Kidney Disease in Children (CKiD) Cohort

BACKGROUND

Few studies have prospectively evaluated the progression of chronic kidney disease (CKD) in children and adolescents, as well as factors associated with progression.

STUDY DESIGN

Prospective multicenter observational cohort study.

SETTING & PARTICIPANTS

496 children and adolescents with CKD enrolled in the Chronic Kidney Disease in Children (CKiD) Study.

PREDICTORS

Proteinuria, hypoalbuminemia, blood pressure, dyslipidemia, and anemia.

OUTCOMES

Parametric failure-time models were used to characterize adjusted associations between baseline levels and changes in predictors and time to a composite event of renal replacement therapy or 50% decline in glomerular filtration rate (GFR).

RESULTS

398 patients had nonglomerular disease and 98 had glomerular disease; of these, 29% and 41%, respectively, progressed to the composite event after median follow-ups of 5.2 and 3.7 years, respectively. Demographic and clinical characteristics and outcomes differed substantially according to the underlying diagnosis; hence, risk factors for progression were assessed in stratified analyses, and formal interactions by diagnosis were performed. Among patients with nonglomerular disease and after adjusting for baseline GFR, times to the composite event were significantly shorter with urinary protein-creatinine ratio > 2mg/mg, hypoalbuminemia, elevated blood pressure, dyslipidemia, male sex, and anemia, by 79%, 69%, 38%, 40%, 38%, and 45%, respectively. Among patients with glomerular disease, urinary protein-creatinine ratio >2mg/mg, hypoalbuminemia, and elevated blood pressure were associated with significantly reduced times to the composite event by 94%, 71%, and 67%, respectively. Variables expressing change in patient clinical status over the initial year of the study contributed significantly to the model, which was cross-validated internally.

LIMITATIONS

Small number of events in glomerular patients and use of internal cross-validation.

CONCLUSIONS

Characterization and modeling of risk factors for CKD progression can be used to predict the extent to which these factors, either alone or in combination, would shorten the time to renal replacement therapy or 50% decline in GFR in children with CKD.

Serum Phosphorus and Progression of CKD and Mortality: A Meta-analysis of Cohort Studies

BACKGROUND

Recent studies have indicated that phosphorus may play an independent pathogenic role in chronic kidney disease (CKD) progression, but some of those studies were underpowered and yielded inconsistent results.

STUDY DESIGN

Systematic review and meta-analysis.

SETTING & POPULATION

Non-dialysis-dependent patients with CKD (transplant recipients were excluded).

SELECTION CRITERIA FOR STUDIES

Studies assessing the risk ratio of serum phosphorus level on kidney failure and mortality for non-dialysis-dependent patients with CKD published from January 1950 to June 2014 were included following systematic searching of MEDLINE, EMBASE, and the Cochrane Library.

PREDICTOR

Serum phosphorus level.

OUTCOME

Kidney failure, defined as doubled serum creatinine level, 50% decline in estimated glomerular filtration rate, or end-stage kidney disease.

RESULTS

In 12 cohort studies with 25,546 patients, 1,442 (8.8%) developed kidney failure and 3,089 (13.6%) died. Overall, every 1-mg/dL increase in serum phosphorus level was associated independently with increased risk of kidney failure (hazard ratio, 1.36; 95% CI, 1.20-1.55) and mortality (hazard ratio, 1.20; 95% CI, 1.05-1.37).

LIMITATIONS

Existence of potential residual confounding could not be excluded.

CONCLUSIONS

This meta-analysis suggests an independent association between serum phosphorus level and kidney failure and mortality among non-dialysis-dependent patients with CKD and suggests that large-scale randomized controlled trials should target disordered phosphorus homeostasis in CKD.

Novel effective drugs for diabetic kidney disease? or not?

INTRODUCTION

Diabetes mellitus is increasingly common worldwide and is expected to affect 592 million people by 2035. The kidney is often involved. A key goal in treating diabetes is to reduce the risk of development of kidney disease and, if kidney disease is already present, to delay the progression to end-stage renal disease (ESRD). This represents a social and ethical issue, as a significant proportion of patients reaching ESRD in developing countries do not have access to renal replacement therapy.

AREAS COVERED

The present review focuses on novel therapeutic approaches for diabetic nephropathy (DN), implemented on the basis of recent insights on its pathophysiology, which might complement the effects of single inhibition of the renin-angiotensin-aldosterone system (RAAS), the cornerstone of renoprotective interventions in diabetes, along with glycemic and blood pressure control.

EXPERT OPINION

Although a plethora of new treatment options has arisen from experimental studies, the number of novel renoprotective molecules successfully implemented in clinical practice over the last two decades is disappointingly low. Thus, new investigational strategies and diagnostic tools - including the appropriate choice of relevant renal end points and the study of urinary proteome of patients - will be as important as new therapeutic interventions to fight DN. Finally, in spite of huge financial interests in replacing the less expensive ACE inhibitors and angiotensin II receptor blockers with newer drugs, any future therapeutic approach has to be tested on top of - rather than instead of - optimal RAAS blockade.

Intact parathyroid hormone levels are associated with increased carotid intima media thickness in HIV infected patients

AIM

Preliminary evidence suggests that intact parathyroid hormone (iPTH) and bone mineral abnormalities may contribute to the development of vascular disease and are associated with reduced survival in the general population. Whether iPTH is associated with subclinical atherosclerosis in HIV-infected individuals has not been elucidated.

METHODS

Cross-sectional study of 470 consecutive HIV-infected patients in whom we measured carotid intima-media thickness (cIMT), and collected demographical, clinical and laboratory data. High-cIMT was defined as a mean IMT above the 75th percentile for the study cohort. Parametric, non-parametric tests and logistic regression analyses were used to compare patients' characteristics between low- and high-cIMT and to test the association between high-cIMT and log-transformed iPTH.

RESULTS

Of the 470 patients, 130 had high-cIMT. High-cIMT subjects were older and more likely to be male and have a history of cardiovascular disease. Glucose, lipid and iPTH levels were lower among low-cIMT subjects (p < 0.05). Unadjusted and multivariable adjusted analyses demonstrated an independent association between high-cIMT and iPTH (fully adjusted OR: 1.74; 95%CI: 1.08-2.79; p = 0.021). Bootstrap and sensitivity analyses confirmed these findings.

CONCLUSIONS

Elevated iPTH was associated with subclinical atherosclerosis in HIV-infected subjects. Of note this association was statistically significant even for iPTH values within the range of normality. The existence of a causal relationship between iPTH and atherosclerosis needs to be fully explored in future investigations.

Sodium thiosulfate attenuates angiotensin II-induced hypertension, proteinuria and renal damage

Hypertension and proteinuria are important mediators of renal damage. Despite therapeutic interventions, the number of patients with end stage renal disease steadily increases. Hydrogen sulfide (H(2)S) is an endogenously produced gasotransmitter with vasodilatory, anti-inflammatory and antioxidant properties. These beneficial characteristics make H(2)S an attractive candidate for pharmacological use in hypertensive renal disease. We investigated the protective properties of H(2)S in angiotensin II (Ang II)-induced hypertensive renal disease in rats. Treatment with the H(2)S donor NaHS and major H(2)S metabolite sodium thiosulfate (STS) during three weeks of Ang II infusion reduced hypertension, proteinuria, oxidative stress and renal functional and structural deterioration. In an ex vivo isolated perfused kidney setup, NaHS, but not STS, reduced intrarenal pressure. The effect of NaHS could partially be explained by its activation of the ATP-sensitive potassium channels. In conclusion, treatment with H(2)S attenuates Ang II-associated functional and structural renal deterioration, suggesting that intervention in H(2)S production pathways has potential therapeutic benefit and might be a valuable addition to the already existing antihypertensive and renoprotective therapies.

Effects of cardiorespiratory fitness on blood pressure trajectory with aging in a cohort of healthy men

BACKGROUND

Although the trajectory of blood pressure (BP) with aging is well known, there is a lack of data on how cardiorespiratory fitness (hereafter referred to as fitness) affects age-associated changes in BP.

OBJECTIVES

The objective of the study was to investigate whether fitness alters the aging-BP trajectory.

METHODS

A cohort from the Aerobics Center Longitudinal Study totaling 13,953 men between 20 and 90 years of age who did not have hypertension, cardiovascular disease, or cancer completed 3 to 28 (mean of 3.8) follow-up medical examinations between 1970 and 2006. Fitness was measured by a maximal treadmill exercise test. Longitudinal data were analyzed using linear mixed models.

RESULTS

Diastolic blood pressure (DBP) tended to increase until nearly 60 years of age, when a decrease was observed. Systolic blood pressure (SBP) tended to increase over all age periods. On multivariate analysis, average SBP increased by 0.30 mm Hg (95% confidence interval: 0.29 to 0.31) with 1-year age increment after adjusting for body fat percent, fitness, resting heart rate, glucose level, triglyceride level, cholesterol level, current smoking, heavy alcohol consumption, and parental history of hypertension. DBP had a yearly increase of 0.14 mm Hg (95% confidence interval: 0.13 to 0.15) before age 60 years. Overall, abnormal SBP (>120 mm Hg) began to occur at approximately 50 years of age and abnormal DBP (>80 mm Hg) began to occur at 60 years of age. Men with higher fitness levels experienced abnormal SBP later than those with low fitness levels.

CONCLUSIONS

Our findings underscore the potential modifying effect of fitness on BP trajectory with aging over the male adult life span. Improving fitness levels might extend the normal SBP and DBP ranges, delaying the development of hypertension.

Independent or synergistic relationship of proteinuria and glomerular filtration rate on patient and renal survival in patients with glomerulonephritis?

BACKGROUND

Glomerular filtration rate (GFR) in patients with chronic kidney disease (CKD) identifies patients at risk for death or end-stage renal disease (ESRD). CKD staging by GFR should incorporate proteinuria to augment risk stratification. We therefore tested the predictive power of the combination of GFR with proteinuria in patients with different histologically-diagnosed types of glomerulonephritis (GN).

METHODS

In a retrospective analysis, 2,687 patients with different forms of GN from 123 Austrian centres were investigated. Full data sets were available from 1,892 subjects. Classes of CKD on the basis of estimated GFR (eGFR) and of proteinuria grouped as <1, 1-3.5, and >3.5 g/24 h were tested for their association with all-cause mortality and ESRD.

RESULTS

During a median follow-up of 130 months [interquartile range (IQR) 90; 178] 478 patients (25.3 %) died. Median eGFR was 49 ml/min/1.73 m(2) (IQR 24; 81) and proteinuria 3.8 g/24 h (IQR 1.7; 8.0). Adjusted multivariate Cox regression indicated that renal survival but not overall survival is related to proteinuria >3.5 g/24 h [as opposed to <1 g/24 h; hazard ratio (HR) 1.91] and shows progression to ESRD. However, subgroup analyses revealed that this risk with proteinuria >3.5 g/24 h exists only in patients with immunoglobulin (Ig)A GN (HR 4.93), miscellaneous GN (HR 1.74), and CKD stage 5 (HR 2.50). Additionally, proteinuria is a risk factor for renal survival in males more than in females with GN and proteinuria >3.5 g/24 h (HR 1.91).

CONCLUSION

Proteinuria is a strong risk factor for renal survival particularly in patients with proteinuria >3.5 g/24 but not for all types of GN, nor for all CKD stages. Proteinuria is not a risk factor for overall survival in patients with GN.