Role of Pulse Pressure on Cardiovascular Risk in Chronic Kidney Disease Patients: Figure 1

Prevalence and associated factors of glomerular hyperfiltration among adult stable sickle cells in Kinshasa, DR Congo

INTRODUCTION

Glomerular hyperfiltration is highly frequent, theoretically dependent on cardiac output, low systemic vascular resistance and hemolysis markers. In sickle cell disease (SCD), hyperfiltration is an extremely common phenomenon and occurred in young and early adult patients. Despite the fact that the glomerular hyperfiltration is known as the early manifestations of sickle cell nephropathy, its burden among adult sickle cell disease in sub-Saharan is poor studied. This study aimed to determine the prevalence and associated factors of hyperfiltration.

METHODS

This was an analytical multicentric cross-sectional study involving stable adult sickle cell patients in Kinshasa, recruited between March and October 2023. Parameters of interest encompasses demographic, clinical, biological, echocardiographic and pulse wave measurement data. Hyperfiltration was defined using the CDK-EPI equation based on cystatin C; eGFR >130 for women and >140 ml/min/1.73m2 for men. We used multivariate logistic regression analysis to search determinants of glomerular hyperfiltration.

RESULTS

Two hundred and fourty six (246) patients with SCD were enrolled. The prevalence of hyperfiltration was 20.7%. In multiple logistic regression analysis, hyperfiltration status was independently associated with age (< 25 years) [3.57 (1.78-7.49); p = 0.027)], female sex [4.36 (2.55-5.62); p = 0.031), CRP (< 6 mg/l) [0.77 (0.61-0.97); p = 0.028)], central systolic pressure (< 100 mmHg) and central diastolic pressure (< 60 mmHg) [0.86(0.74-0.98), p = 0.028)], [(0.83 (0.71-0.98); p = 0.032)].

CONCLUSION

One out of five SS adults exhibits hyperfiltration, which is associated with young age and female sex, whereas low CRP and blood pressure were negative risk factors.

Central and Peripheral Hemodynamics in Young Adults Who Use Water Pipes and the Acute Effects of Water-Pipe Use

BACKGROUND

Tobacco use via water pipe (commonly referred to as water-pipe smoking [WPS]) is popular among young adults globally and exposes those who smoke to toxicants.

RESEARCH QUESTION

Is WPS associated with impaired measures of arterial function and does WPS acutely impair these measures in young adults?

STUDY DESIGN AND METHODS

We assessed heart rate (HR), brachial and aortic BP, HR-adjusted augmentation index (AI), and carotid-femoral pulse wave velocity (CFPWV) in 62 individuals who use water pipes and 34 individuals who have never used a water pipe recruited from the community (mean age, 22.5 ± 3.0 years; 48% female). Measurements were obtained before and after an outdoor session of WPS among participants who use water pipes and among the control group of participants who have never used a water pipe. Measurements were compared after vs before exposure and between those who use and those who do not use water pipes, adjusting for possible confounders using linear regression.

RESULTS

Participants who use water pipes and control participants had similar demographic characteristics. BP and HR increased acutely after WPS (brachial systolic BP by 4.13 mm Hg [95% CI, 1.91-6.36 mm Hg]; aortic systolic BP by 2.31 mm Hg [95% CI, 0.28-4.33 mm Hg]; brachial diastolic BP by 3.69 mm Hg [95% CI, 1.62-5.77 mm Hg]; aortic diastolic BP by 3.03 mm Hg [95% CI, 0.74-5.33 mm Hg]; and HR by 7.75 beats/min [95% CI, 5.46-10.04 beats/min]), but not in the control group. AI was significantly higher in participants who use water pipes compared with those who do not (9.02% vs 3.06%; P = .03), including after adjusting for BMI and family history of cardiovascular disease (β = 6.12; 95% CI, 0.55-11.69; P = .03) and when assessing habitual tobacco use via water-pipe extent (water pipes used/day × water-pipe use duration) in water-pipe-years (β = 2.51/water-pipe-year; 95% CI, 0.10-4.92/water-pipe-year; P = .04). However, CFPWV was similar in those who use water pipes and those who do not, and AI and CFPWV did not change acutely after WPS.

INTERPRETATION

In apparently healthy young individuals from the community, habitual WPS was associated with increased AI, a predictor of cardiovascular risk, and one WPS session acutely increased HR and brachial and aortic BP.

Blood Pressure and Mortality in the 4D Study

INTRODUCTION

Systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) are risk factors for cardiovascular mortality (CVM). Pulse pressure (PP) is an easily available parameter of vascular stiffness, but its impact on CVM in chronic dialysis patients with diabetes is unclear.

METHODS

Therefore, we have examined the predictive value of baseline, predialytic PP, SBP, DBP, and MAP in the German Diabetes and Dialysis (4D) study, a prospective, randomized, double-blind trial enrolling 1,255 patients with type 2 diabetes on hemodialysis in 178 German dialysis centers.

RESULTS

Mean age was 66.3 years, mean blood pressure 146/76 mm Hg, mean time suffering from diabetes 18.1 years, and mean time on maintenance dialysis 8.3 months. Considered as continuous variables, PP, MAP, SBP, and DBP could not provide a significant mortality prediction for either cardiovascular or all-cause mortality. After dividing the cohort into corresponding tertiles, we also did not detect any significant mortality prediction for PP, SBP, DBP, or MAP, both for all-cause mortality and CVM after adjusting for age and sex. Nevertheless, when comparing the HR plots of the corresponding blood pressure parameters, a pronounced U-curve was seen for PP for both all-cause mortality and CVM, with the trough range being 70-80 mm Hg.

DISCUSSION

In patients with end-stage renal disease and long-lasting diabetes mellitus predialytic blood pressure parameters at study entry are not predictive for mortality, presumably because there is a very high rate of competing mortality risk factors, resulting in overall very high rates of all-cause and CVM that may no longer be significantly modulated by blood pressure control.

Association between pulse pressure, systolic blood pressure and the risk of rapid decline of kidney function among general population without hypertension: results from the China health and retirement longitudinal study (CHARLS)

BACKGROUND

Association between blood pressure (BP) and kidney function among the middle and old aged general population without hypertension remains unclear.

METHODS

Participants aged ≥ 45 years, with complete data in 2011 and 2015 interviews of the China Health and Retirement Longitudinal Study(CHARLS), and without pre-existing hypertension were included. Systolic BP (SBP) was categorized as low (< 120 mmHg), medium (120-129 mmHg), and high (120-139 mmHg). Diastolic BP (DBP) was categorized as low (< 60 mmHg), medium (60-74 mmHg), and high (75-89 mmHg). Pulse pressure (PP) was categorized as normal (< 60 mmHg) and high (≥ 60 mmHg). The outcome was defined as rapid decline of estimated glomerular filtration rate(eGFR, decline ≥ 4 ml/min/1.73 m2/year). BP combination was designed according to the category of SBP and PP. The association between BP components, types of BP combination, and the risk of rapid decline of eGFR was analyzed using multivariate logistic regression models, respectively. Age-stratified analyses were conducted.

RESULTS

Of 4,534 participants included, 695(15.3%) individuals were recognized as having rapid decline of eGFR. High PP[odds ratio(OR) = 1.34, 95%confidence interval(CI) 1.02-1.75], low SBP (OR = 1.28, 95%CI 1.03-1.59), and high SBP (OR = 1.32, 95% CI 1.02-1.71) were significantly associated with the risk of eGFR decline. Low SBP were associated with 65% increment of the risk of eGFR decline among participants aged < 55 years. The combination of high SBP and high PP (OR = 1.79, 95% CI 1.27-2.54) and the combination of low SBP and high PP (OR = 3.07, 95% CI 1.24-7.58) were associated with the increased risk of eGFR decline among the middle and old aged general population.

CONCLUSION

Single and combination of high PP and high SBP could be the risk indicators of eGFR decline among the middle and old aged general population.

Association between long-term pulse pressure trajectories and risk of end-stage renal diseases in incident malignant hypertensive nephropathy: a cohort study

OBJECTIVE

The trajectories of pulse pressure (PP) might affect the prognosis of malignant hypertensive nephropathy (MHN). We aimed to describe the association between PP trajectories and the future risk of end-stage renal disease and to identify and compare the associated patient characteristics of any distinct trajectory patterns in MHN patients.

METHODS

Patients with newly diagnosed biopsy-proven MHN 2010-2015 were included. Latent class growth analysis was applied to the PP measured over 3 years prior to biopsy to identify distinct trajectories. Concurrent systolic blood pressure, diastolic blood pressure, plasma creatinine, and 24-h urine protein measurements for each trajectory group were modelled using generalized estimating equations. The risk of end-stage renal disease (with kidney replacement therapy as a proxy) was estimated using Logistic regression.

RESULTS

Two hundred three patients were included (median-age 34 years, and 19.7% female). A two-group cubic model was optimal, with trajectories distinguished by the rate of PP and absolute level at final measurement. Trajectory Group-1 (n = 84) was characterized by 'first-increased-then-decreased' PP and trajectory Group-2 (n = 119) was characterized by 'first-decreased-then-increased' PP over 3 years prior to biopsy. Systolic and diastolic blood pressures, plasma creatinine, and 24-h urine protein were differed by the trajectory group. Baseline characteristics differed substantially between trajectory groups. Compared with Group-1, Group-2 had a 66% greater risk of developing into end-stage renal disease in the subsequent 3 years.

CONCLUSIONS

Two distinct 3-year trajectories for PP exist with MHN. Early introduction of intensive antihypertensive treatment might delay the development of end-stage renal disease among patients with malignant hypertension.

The Optimal Haemoglobin Target in Dialysis Patients May Be Determined by Its Contrasting Effects on Arterial Stiffness and Pressure Pulsatility

Introduction

It remains unclear why the optimal haemoglobin target is lower in patients with chronic kidney disease (CKD) than in non-CKD persons. Arteriosclerosis and consequent impaired arterial function comprise a central cardiovascular risk mechanism in CKD. We hypothesized that the optimal haemoglobin target depends on its opposing effects on arterial stiffness and pressure pulsatility in CKD.

Methods

Arterial stiffness (aortic pulse wave velocity), wave reflection (augmentation index, reflected wave pressure and reflection magnitude), and pressure pulsatility (central systolic and pulse pressure, peripheral pulse pressure, pressure amplification and forward wave pressure) were assessed in 48 dialysis patients.

Results

In established confounder and diabetes adjusted linear regression models, haemoglobin levels were directly associated with arterial stiffness (partial R=0.366, p=0.03) and inversely with central systolic pressure (partial R=−0.344, p=0.04), central pulse pressure (partial R=−0.403, p=0.01), peripheral pulse pressure (partial R=−0.521, p=0.001) and forward wave pressure (partial R=−0.544, p=0.001). The presence of heart failure and use of angiotensin converting enzyme inhibitors or angiotensin receptor blockers and erythropoietin stimulating agents did not materially alter these relationships upon further adjustment for the respective characteristics in the models, and in sensitivity analyses. In receiver operator characteristic curve analysis, the optimal haemoglobin concentration cut-off values in predicting arterial stiffness and increased central pulse pressure were remarkably similar at 10.95 g/dl and 10.85 g/dl, respectively, and with clinically useful sensitivities, specificities and positive and negative predictive values. In logistic regression models, a haemoglobin value of >10.9 mg/dl was associated with both arterial stiffness (>10 m/sec; OR (95% CI) = 10.48 (1.57–70.08), p=0.02) and normal central pulse pressure (>50 mmHg; OR (95% CI) = 7.55 (1.58–36.03), p=0.01).

Conclusion

This study suggests that the optimal haemoglobin target in dialysis patients is ~11g/dl and determined by its differential and contrasting effects on arterial stiffness and pressure pulsatility.

Feature and impact of guideline-directed medication prescriptions for heart failure with reduced ejection fraction accompanied by chronic kidney disease

Background: With respect to total mortality and cardiovascular mortality, the feature and impact of guideline-directed medication (GDM) prescriptions for heart failure with reduced ejection fraction (HFrEF) with chronic kidney disease (CKD) are unknown. Therefore, we aimed to determine these aspects. Methods: GDM prescriptions and their impact on discharged patients with and without CKD were analyzed. To analyze differences in one-year clinical outcomes, propensity score matching was conducted on a cohort of patients with concomitant HFrEF and CKD who received more and fewer GDM prescriptions. Results: A total of 1509 patients were enrolled in Taiwan's HFrEF registry from May 2013 to October 2014, and 1275 discharged patients with complete one-year follow-up were further analyzed. Of these patients, 468 (36.7%) had moderate CKD, whereas 249 (19.5%) had advanced CKD. Patients with advanced CKD received fewer prescribed GDMs than other patients. Multivariate analysis revealed that peripheral arterial occlusive disease, thyroid disorder, advanced HF at discharge, diastolic blood pressure, digoxin use, and fewer prescribed GDMs were independent predictors of one-year total mortality. After propensity score matching, patients with fewer prescribed GDMs had higher one-year total mortality rate than those with more prescribed GDMs (P=0.036). Conclusions: CKD at discharge from HF hospitalization was associated with fewer GDM prescriptions, particularly in patients with more advanced CKD. The propensity-matched analysis indicated that more GDM prescriptions led to better clinical outcomes in HFrEF patients with CKD. Careful interpretation of changes in renal function during HF hospitalization may improve GDM prescriptions.

Chronic stress and age-related pattern of blood pressure: A cross-sectional study in rural China

OBJECTIVE

Chronic stress is a risk factor for hypertension in adults. However, there is conflicting evidence for older adults. We hypothesized that age-related arterial stiffening, which leads to a lower blood pressure (especially diastolic blood pressure [DBP]), is more pronounced among older adults with high vs low stress. The objectives of this study were (a) to investigate age-related trends in systolic and DBPs among adults in rural Fujian, China, and (b) to examine differences in age-related blood pressure trends according to levels of stress by using Epstein-Barr virus (EBV) antibody titer as a marker of chronic stress status.

METHODS

We collected cross-sectional data from 764 rural community-dwelling adults in rural Fujian, China (mean age = 59.4). Participants were categorized into high and low stress groups by median split of EBV antibody titer. A least-squares regression analysis was used to investigate the association between age and blood pressures.

RESULTS

We observed an inverted U-shaped association between age and DBP, while there was a linear association between age and systolic blood pressure in the overall sample. When stratified by stress, the inverted U-shaped associations with age (both systolic and DBPs) were seen only among those with high stress; DBP peaked at the age of ~68 years, and the declining trend later in life was more clearly observed among those with high chronic stress.

DISCUSSION

Decrease of DBP was more pronounced among older adults with high vs low chronic stress in rural China.

Association of pulse pressure, pulse pressure index, and ambulatory arterial stiffness index with kidney function in a cross-sectional pediatric chronic kidney disease cohort from the CKiD study

The morbidity and mortality of adult and pediatric chronic kidney disease (CKD) and end-stage renal disease (ESRD) populations are mainly driven by cardiovascular disease (CVD). Improving CVD outcomes focuses on risk assessment of factors including diastolic blood pressure (DBP), systolic blood pressure (SBP), left ventricular mass index (LVMI), pulse pressure (PP), and pulse pressure index (PPi), which is calculated as PP/SBP. These markers are also proven predictors of CKD progression; however, their role in children has not been established. This study aims to evaluate the relationship between PP, PPi, ambulatory arterial stiffness index (AASI), and proteinuria with kidney function in pediatric CKD patients; it is a retrospective analysis of 620 patients (1-16 years) from the NIDDK Chronic Kidney Disease in Children (CKiD) registry. The authors analyzed data for three separate cohorts: an overall CKD as well as immunological versus non-immunological cause for CKD groups. An inverse relationship was found between SBP, DBP, and PP with iGFR and LVMI in the overall CKD group. Our immunological CKD subgroup showed significantly higher serum creatinine, SBP, DBP, and PP values with significantly lower serum albumin levels compared to the non-immunological group. There were no significant differences with iohexol-based glomerular filtration rate (iGFR), LVMI, PPi, or high-sensitivity C-reactive protein (hs-CRP) between the two groups. A subgroup analysis demonstrated that SBP, DBP, and PP all correlated significantly with LVMI in the immunological CKD patients but not the non-immunological subgroup. Additionally, AASI data in the overall CKD population were significantly correlated with PP, PPi, and DBP. This study is one of the first to correlate noninvasive measurements of vascular compliance including PP, PPi, and AASI with iGFR and LVMI in a pediatric CKD cohort. Improving our understanding of surrogate markers for early CVD is integral to improving the care of pediatric CKD population as these patients have yet to develop the hard end points of ESRD, heart failure, myocardial infarction, or stroke.

Triglyceride/HDL-cholesterol ratio and plasminogen activator inhibitor-1 independently predict high pulse pressure in sickle cell trait and disease

We hypothesised that TG/HDL-C ratio and PAI-1 would be associated with high pulse pressure (PP) in young adults with sickle cell trait (SCT) and sickle cell disease (SCD). We compared the clinical, biochemical, and cardiometabolic parameters among individuals with normal genotype (HbAA; n = 60), SCT (HbAS; n = 60), and SCD (HbSS; n = 60), all in steady state. Using multivariate linear regression analysis, high PP was positively related to TG/HDL-C ratio in SCT (β = 0.307; p = .014) and PAI-1 (β = 0.499; p = .001) in SCD. The curve of receiver operating characteristic also showed that TG/HDL-C ratio and PAI-1 are efficient predictors of high PP in SCT carriers and SCD patients, respectively. This study suggests that increased levels of TG/HDL-C ratio and PAI-1 may be salient risk factors that would promote the development of arterial stiffness and other CVD in SCT carriers and SCD patients.

The association of profilin-1 levels with survival in chronic kidney disease

BACKGROUND

Profilin-1 is a ubiquitous, actin-binding protein that plays an important role in the regulation of actin polymerization and cytoskeleton remodelling and contributes to vascular dysfunction. We conducted this study to investigate the association of serum profilin-1 levels with fatal and nonfatal CVE in a cohort of patients with stage 1-5 CKD.

MATERIALS AND METHODS

Serum concentrations of profilin-1 levels were determined by enzyme-linked immunosorbent assay. Endothelium-dependent vasodilatation (flow-mediated dilatation [FMD]) and endothelium-independent vasodilatation (nitroglycerine-mediated dilatation [NMD]) of the brachial artery were assessed noninvasively, using high-resolution ultrasound.

RESULTS

Both fatal and nonfatal CVE were significantly higher in patients with high profilin-1 levels. Kaplan-Meier survival curves showed that patients with profilin-1 below the median value (114 pg/mL) had higher cumulative survival compared with patients who had profilin-1 levels above the median value (log-rank test, P < .001).

CONCLUSIONS

This is the first study that demonstrates the serum profilin-1 is independently associated with endothelial dysfunction, cardiovascular events and survival in patients with CKD.

The Relationship Between Pulse Pressure, the Estimated Glomerular Filtration Rate, and Urine Microalbumin/Creatinine Ratio in Korean Adults

BACKGROUND/AIMS

Pulse pressure (PP) is a predictor of adverse outcomes in patients on haemodialysis. Thus, the present study was conducted to assess the relationship between PP, estimated glomerular filtration rate (eGFR), and urine microalbumin/creatinine ratio (uACR) in Korean adults.

METHODS

Data of 9,409 adults (4,206 men and 5,203 women) aged ≥ 20 years from the Sixth Korean National Health and Nutrition Examination Survey (2013-2014) were analyzed.

RESULTS

A multivariate analysis revealed that systolic blood pressure (SBP) (β = -0.170, 95% confidence interval [CI], -0.216 to -0.159), diastolic blood pressure (DBP) (β = 0.088, 95% CI 0.108-0.200; p < 0.001), and PP (β = -0.134, 95% CI -0.215 to -0.157) were significant factors determining eGFR. In contrast, SBP (β = 0.152, 95% CI, 0.985-1.456; p < 0.001), DBP (β = -0.062, 95% CI -1.141 to -0.442; p < 0.001), and PP (β = 0.118, 95% CI 0.965-1.436; p < 0.001) were the significant factors determining uACR. The odds ratios (ORs) of a high PP (PP ≥ 60 mmHg) with a normal group [eGFR ≥ 60 ml/min/1.73 m2 and uACR < 30 mg/g] as a reference were significant for decreased eGFR [eGFR < 60 ml/min/1.73 m2, 1.484 (95% CI, 1.003-2.196)], elevated uACR [uACR ≥ 30 mg/g, 2.592 (95% CI, 2.085-3.223)], and decreased eGFR plus elevated uACR [eGFR < 60 ml/min/1.73 m2 and uACR ≥ 30 mg/g, 3.889 (95% CI, 2.519-6.004)].

CONCLUSION

Enhanced PP was associated with a decreased eGFR and an increase in uACR in Korean adults. In addition, the PP increased greatly when a decrease in eGFR and an increase in uACR appeared simultaneously.

Pulse pressure tracking from adolescence to young adulthood: contributions to vascular health

PURPOSE

We examined whether exposure to high PP in adolescence predicts carotid artery intima-media thickness (IMT) and stiffness indices at young adulthood.

METHODS

Seventy-nine participants had their brachial systolic (SBP) and diastolic blood (DBP) pressures taken at the age of 15-16 years and later at young adulthood (29-31 years). Carotid IMT, distensibility and stiffness index β were measured at young adulthood. Linear and logistical regression analysis were performed.

RESULTS

PP at adolescence and at young adulthood predicted vascular health independently of sex, body mass index, and mean arterial pressure, explaining up to 37% of the variance. When analyzing its single constituents, at adolescence DBP was more predictive of vascular health, whereas DBP and SBP were equally important at young adulthood. Adolescents with high PP were at risk for increased carotid IMT (OR: 4.04-4.09), even if PP decreased at young adulthood. Young adults with high PP were at risk for increased stiffness regardless of adolescence PP (OR: 4.64-7.35).

CONCLUSION

PP at adolescence and young adulthood may be a better predictor of early pathological changes in carotid artery structure and stiffness. Whereas carotid IMT in young adults appears to be influenced by PP at adolescence, carotid stiffness depends primarily on current PP.

Different components of blood pressure are associated with increased risk of atherosclerotic cardiovascular disease versus heart failure in advanced chronic kidney disease

Blood pressure is a modifiable risk for cardiovascular disease (CVD). Among hemodialysis patients, there is a U-shaped association between blood pressure and risk of death. However, few studies have examined the association between blood pressure and CVD in patients with stage 4 and 5 chronic kidney disease. Here we studied 1795 Chronic Renal Insufficiency Cohort (CRIC) Study participants with estimated glomerular filtration rate <30 ml/min per 1.73 m² and not on dialysis. The association of systolic (SBP), diastolic (DBP), and pulse pressure with the risk of physician-adjudicated atherosclerotic CVD (stroke, myocardial infarction, or peripheral arterial disease) and heart failure was tested using Cox regression adjusted for demographics, comorbidity and medications. There was a significant association with higher SBP (adjusted hazard ratio 2.04 [95% confidence interval: 1.46-2.84]) for SBP over 140 vs under 120 mmHg, higher DBP (2.52 [1.54-4.11]) for DBP >90 mm Hg versus <80 mm Hg and higher pulse pressure (2.67 [1.82-3.92]) for pulse pressure >68 mm Hg versus <51 mm Hg with atherosclerotic CVD. For heart failure, there was a significant association with higher pulse pressure only (1.42 [1.05-1.92]) for pulse pressure >68 mm Hg versus <51 mmHg, but not for SBP or DBP. Thus, among participants with stage 4 and 5 chronic kidney disease, there was an independent association between higher SBP, DBP, and pulse pressure with the risk of atherosclerotic CVD, whereas only higher pulse pressure was independently associated with a greater risk of heart failure. Further trials are needed to determine whether aggressive reduction of blood pressure decreases the risk of CVD events in patients with stage 4 and 5 chronic kidney disease.

Pulse Pressure and Cognitive Decline in Stroke Patients With White Matter Changes

The authors hypothesized that both high and low pulse pressure (PP) may predict cognitive decline in stroke/transient ischemic attack (TIA) patients with white matter changes (WMCs). The authors prospectively followed up 406 ischemic stroke/TIA patients with confluent WMCs over 18 months. PP was measured at 3 to 6 months after stroke/TIA and categorized into four groups by quartile. Cognition was assessed 3 to 6 months and 15 to 18 months after stroke/TIA using the Clinical Dementia Rating and Mini-Mental State Examination (MMSE). Logistic regression showed that patients in the first quartile of PP had a 5.9-fold higher risk for developing cognitive decline than patients in the third quartile (odds ratio, 5.9; 95% confidence interval, 1.7-20.6), while patients in the fourth quartile had a 3.5-fold higher risk for cognitive decline than those in the third quartile (odds ratio, 3.5; 95% confidence interval, 1.0-12.4). This U-shaped relationship was also evident between PP and cognitive decline in MMSE, underlining the role of arterial stiffness and hypoperfusion in cognitive decline related to small vessel disease.

Iron-hepcidin dysmetabolism, anemia and renal hypoxia, inflammation and fibrosis in the remnant kidney rat model

Anemia is a common complication of chronic kidney disease (CKD) that develops early and its severity increases as renal function declines. It is mainly due to a reduced production of erythropoietin (EPO) by the kidneys; however, there are evidences that iron metabolism disturbances increase as CKD progresses. Our aim was to study the mechanisms underlying the development of anemia of CKD, as well as renal damage, in the remnant kidney rat model of CKD induced by 5/6 nephrectomy. This model of CKD presented a sustained degree of renal dysfunction, with mild and advanced glomerular and tubulointerstitial lesions. Anemia developed 3 weeks after nephrectomy and persisted throughout the protocol. The remnant kidney was still able to produce EPO and the liver showed an increased EPO gene expression. In spite of the increased EPO blood levels, anemia persisted and was linked to low serum iron and transferrin levels, while serum interleukin (IL)-6 and high sensitivity C-reactive protein (hs-CRP) levels showed the absence of systemic inflammation. The increased expression of duodenal ferroportin favours iron absorption; however, serum iron is reduced which might be due to iron leakage through advanced kidney lesions, as showed by tubular iron accumulation. Our data suggest that the persistence of anemia may result from disturbances in iron metabolism and by an altered activity/function of EPO as a result of kidney cell damage and a local inflammatory milieu, as showed by the increased gene expression of different inflammatory proteins in the remnant kidney. In addition, this anemia and the associated kidney hypoxia favour the development of fibrosis, angiogenesis and inflammation that may underlie a resistance to EPO stimuli and reduced iron availability. These findings might contribute to open new windows to identify putative therapeutic targets for this condition, as well as for recombinant human EPO (rHuEPO) resistance, which occurs in a considerable percentage of CKD patients.

Skin autofluorescence as a novel marker of vascular damage in children and adolescents with chronic kidney disease

BACKGROUND

Skin autofluorescence (sAF) was examined as a marker of the accumulation of advanced glycation end products (AGEs) in tissues of children with chronic kidney disease (CKD) in relation to renal function, dialysis modality and markers of endothelial inflammation and dysfunction.

METHODS

A total of 76 children with CKD were enrolled in the study, of whom 20 children were on hemodialysis (HD), 20 were on peritoneal dialysis (PD) and 36 were treated conservatively. A control group of 26 healthy subjects was also included in the study. In all children, sAF intensity, carotid intima-media (cIMT) thickness and plasma concentrations of sE-selectin, matrix metalloproteinase 9 (MMP-9), tissue inhibitor of metalloproteinase 1 (TIMP-1), asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA) and plasminogen activator inhibitor type 1 (PAI-1) were measured.

RESULTS

Compared to the controls, children with CKD had significantly elevated sAF levels. sAF in the children with CKD was positively correlated with sE-selectin, MMP-9, TIMP-1, ADMA, SDMA and PAI-1 levels. In the predialysis group (conservative treatment) sAF levels were positively correlated with sE-selectin and ADMA levels and negatively correlated with glomerular filtration rate. Multiple regression analysis showed a significant association of sAF with sE-selectin and MMP-9 in CKD children.

CONCLUSIONS

The results reveal that AGEs were accumulated in the children with CKD. This accumulation was related to early vascular changes and a number of biochemical vascular risk markers. sAF measurement, as a noninvasive method, may be useful for identification of clinical risk factors of vascular disease in CKD children.

Elevated pulse pressure is associated with hemolysis, proteinuria and chronic kidney disease in sickle cell disease

A seeming paradox of sickle cell disease is that patients do not suffer from a high prevalence of systemic hypertension in spite of endothelial dysfunction, chronic inflammation and vasculopathy. However, some patients do develop systolic hypertension and increased pulse pressure, an increasingly recognized major cardiovascular risk factor in other populations. Hence, we hypothesized that pulse pressure, unlike other blood pressure parameters, is independently associated with markers of hemolytic anemia and cardiovascular risk in sickle cell disease. We analyzed the correlates of pulse pressure in patients (n  =  661) enrolled in a multicenter international sickle cell trial. Markers of hemolysis were analyzed as independent variables and as a previously validated hemolytic index that includes multiple variables. We found that pulse pressure, not systolic, diastolic or mean arterial pressure, independently correlated with high reticulocyte count (beta  =  2.37, p  =  0.02) and high hemolytic index (beta  =  1.53, p = 0.002) in patients with homozygous sickle cell disease in two multiple linear regression models which include the markers of hemolysis as independent variables or the hemolytic index, respectively. Pulse pressure was also independently associated with elevated serum creatinine (beta  =  3.21, p  =  0.02), and with proteinuria (beta  =  2.52, p  =  0.04). These results from the largest sickle cell disease cohort to date since the Cooperative Study of Sickle Cell Disease show that pulse pressure is independently associated with hemolysis, proteinuria and chronic kidney disease. We propose that high pulse pressure may be a risk factor for clinical complications of vascular dysfunction in sickle cell disease. Longitudinal and mechanistic studies should be conducted to confirm these hypotheses.

The effect of hyperuricemia on endothelial biomarkers and renal function in kidney allograft recipients

BACKGROUND

Uric acid may play a pathogenic role in hypertension, cardiovascular morbidity, and kidney disease. The aim of this study was to assess the effect of serum uric acid on biomarkers of endothelial activation and renal function in kidney allograft recipients during 30 months of follow-up.

METHODS

The study included 100 allograft recipients with stable renal function (estimated glomerular filtration rate (eGFR) >60 mL/min). The study was performed 34 ± 12 months after transplantation. The patients were followed prospectively for 30 months. Seventy patients displayed hyperuricemia (uric acid 7.5 ± 1.0 mg/dL) and 30 normouricemia (5.5 ± 0.9 mg/dL). Concentrations of plasma resistin, soluble vascular cell adhesion molecule 1 (sVCAM-1), soluble CD146, and high-sensitivity C-reactive protein (hs-CRP) were assessed in patients at the beginning and after 30 months of follow-up. Clinical outcomes and biomarker values were analyzed in these groups and compared to a control group of 26 healthy volunteers.

RESULTS

Concentrations of resistin and CD146 were increased among the hyperuricemia versus the normouricemic group (P < .05). Serum uric acid level correlated with sVCAM-1, hs-CRP, resistin, and sCD146 concentration in both groups of kidney recipients (P < .01). Serum creatinine concentrations correlated with sVCAM-1, resistin, and sCD146 concentrations (P < .01). There were significant direct correlations between uric acid and the number of antihypertensive agents (P < .001) and inverse correlations between eGFR (P < .001) and high-density lipoprotein cholesterol (P < .04). Pulse pressure increased in hyperuricemic patients during follow-up (P < .05). The decrease in eGFR during the 30-month follow-up was similar in both groups. No subject progressed to kidney allograft failure. Patient and graft survivals were 98% among hyperuricemic and 96.7% among normouricemic individuals.

CONCLUSIONS

Hyperuricemia may injure endothelial function via resistin-dependent mechanisms. It represents a risk factor for arterial stiffness. The elevated serum uric acid may not have a causal role in the progression of renal transplant injury over 30 months of follow-up.

Recombinant human erythropoietin treatment protects the cardio-renal axis in a model of moderate chronic renal failure

Chronic kidney disease (CKD) patients develop anemia because of the low kidney erythropoietin (EPO) production, thus promoting cardiovascular complications. The degree of renal insufficiency might determine the moment to start recombinant human erythropoietin (rhEPO) therapy, but the molecular basis for these options deserves better elucidation. This study aimed to clarify the cardio-renal effects of earlier rhEPO therapy in rats with moderate chronic renal failure (CRF). Four groups of rats were evaluated for 15 weeks (control; rhEPO - 50 IU/kg/week; CRF - 3/4 nephrectomy; CRF + rhEPO) to assess renal and hematology data, EPO levels, blood pressure, heart rate, peripheral catecholamines contents, serum-transforming growth factor-β1 (TGF-β1), kidney gene expression of EPO, Caspase 9 (Casp9), and vascular endothelial growth factor (Vegf). This model of moderate CRF showed moderate and corrected anemia, hypertension, tachycardia, sympathetic overactivity, and increased serum TGF-β1 content. The remnant kidney showed a proliferative profile, with hypertrophy, downregulated gene expression of EPO, and upregulated gene expression of Vegf and Casp9. rhEPO treatment promoted erythrocytosis and prevented tachycardia and catecholamines increment, with a rise of serum TGF-β1. Furthermore, the decreased kidney gene expression of EPO and the overexpression of Casp9 were prevented, demonstrating a renoprotective action on the remnant kidney. In conclusion, rhEPO therapy promotes a protective effect on the cardio-renal axis, which might be mainly attributed to its pro-proliferative and anti-apoptotic properties. These findings might recommend its use in earlier stages of CRF, acting as an erythropoiesis stimulating agent, to efficiently correct not only the anemia, one of the major complications in these patients, but also the succeeding adverse cardio-renal effects.

Pharmacogenomics: a new paradigm to personalize treatments in nephrology patients

Although notable progress has been made in the therapeutic management of patients with chronic kidney disease in both conservative and renal replacement treatments (dialysis and transplantation), the occurrence of medication-related problems (lack of efficacy, adverse drug reactions) still represents a key clinical issue. Recent evidence suggests that adverse drug reactions are major causes of death and hospital admission in Europe and the United States. The reasons for these conditions are represented by environmental/non-genetic and genetic factors responsible for the great inter-patient variability in drugs metabolism, disposition and therapeutic targets. Over the years several genetic settings have been linked, using pharmacogenetic approaches, to the effects and toxicity of many agents used in clinical nephrology. However, these strategies, analysing single gene or candidate pathways, do not represent the gold standard, being the overall pharmacological effects of medications and not typically monogenic traits. Therefore, to identify multi-genetic influence on drug response, researchers and clinicians from different fields of medicine and pharmacology have started to perform pharmacogenomic studies employing innovative whole genomic high-throughput technologies. However, to date, only few pharmacogenomics reports have been published in nephrology underlying the need to enhance the number of projects and to increase the research budget for this important research field. In the future we would expect that, applying the knowledge about an individual's inherited response to drugs, nephrologists will be able to prescribe medications based on each person's genetic make-up, to monitor carefully the efficacy/toxicity of a given drug and to modify the dosage or number of medications to obtain predefined clinical outcomes.

Calcimimetics for the Treatment of Secondary Hyperparathyroidism in Peritoneal Dialysis Patients

Secondary hyperparathyroidism is a common complication in patients with end-stage renal disease. It has been associated with increased cardiovascular events and mortality. Traditional therapy has been based on vitamin D analogs and phosphate binders; but these therapies often do not control secondary hyperparathyroidism, particularly in peritoneal dialysis patients for whom phosphate clearances are limited and intravenous vitamin D is impractical. Cinacalcet, a calcimimetic, suppresses parathormone secretion by interacting with the calcium-sensing receptor on the surface of parathyroid gland cells. The resulting suppression of parathyroid hormone secretion produces a reduction in serum phosphate level and CaxPO4 product. The present paper reviews the efficacy of cinacalcet in the management of secondary hyperparathyroidism in peritoneal dialysis patients.