Handgrip strength and mortality in a cohort of kidney failure patients: Comparative analysis of different normalization methods

OBJECTIVES

Reduced handgrip strength (HGS) is associated with adverse clinical outcomes. We analyzed and compared associations of HGS with mortality risk in dialysis patients, using different normalization methods of HGS.

METHODS

HGS and clinical and laboratory parameters were measured in a cohort of 446 incident dialysis patients (median age 56 y, 62% men). The area under the receiver operating characteristic curve (AUROC) was used to compare different normalization methods of HGS as predictors of mortality: absolute HGS in kilograms; HGS normalized to height, weight, or body mass index; and HGS of a reference population of sex-matched controls (percentage of the mean HGS value [HGS%]). Multivariate linear regression analysis was used to assess HGS predictors. Competing risk regression analysis was used to evaluate 5-year all-cause mortality risk. Differences in survival time between HGS% tertiles were quantitated by analyzing the restricted mean survival time.

RESULTS

The AUROC for HGS% was higher than the AUROCs for absolute or normalized HGS values. Compared with the high HGS% tertile, low HGS% (subdistribution hazard ratio [sHR] = 2.36; 95% CI, 1.19-3.70) and middle HGS% (sHR = 1.79; 95% CI, 1.12-2.74) tertiles were independently associated with higher all-cause mortality and those with high HGS% tertile survived on average 7.95 mo (95% CI, 3.61-12.28) and 18.99 mo (95% CI, 14.42-23.57) longer compared with middle and low HGS% tertile, respectively.

CONCLUSIONS

HGS% was a strong predictor of all-cause mortality risk in incident dialysis patients and a better discriminator of survival than absolute HGS or HGS normalized to body size dimensions.

Epigenetic clocks indicate that kidney transplantation and not dialysis mitigate the effects of renal ageing

BACKGROUND

Chronic kidney disease (CKD) is an age-related disease that displays multiple features of accelerated ageing. It is currently unclear whether the two treatment options for end-stage kidney disease (dialysis and kidney transplantation [KT]) ameliorate the accelerated uremic ageing process.

METHODS

Data on clinical variables and blood DNA methylation (DNAm) from CKD stage G3-G5 patients were used to estimate biological age based on blood biomarkers (phenotypic age [PA], n = 333), skin autofluorescence (SAF age, n = 199) and DNAm (Horvath, Hannum and PhenoAge clocks, n = 47). In the DNAm cohort, we also measured the change in biological age 1 year after the KT or initiation of dialysis. Healthy subjects recruited from the general population were included as controls.

RESULTS

All three DNAm clocks indicated an increased biological age in CKD G5. However, PA and SAF age tended to produce implausibly large estimates of biological age in CKD G5. By contrast, DNAm age was 4.9 years (p = 0.005) higher in the transplantation group and 5.9 years (p = 0.001) higher in the dialysis group compared to controls. This age acceleration was significantly reduced 1 year after KT, but not after 1 year of dialysis.

CONCLUSIONS

Kidney failure patients displayed an increased biological age as estimated by DNAm clocks compared to population-based controls. Our results suggest that KT, but not dialysis, partially reduces the age acceleration.

Phenylacetylglutamine and trimethylamine N-oxide: Two uremic players, different actions

BACKGROUND

Chronic kidney disease (CKD) patients exhibit a heightened cardiovascular (CV) risk which may be partially explained by increased medial vascular calcification. Although gut-derived uremic toxin trimethylamine N-oxide (TMAO) is associated with calcium-phosphate deposition, studies investigating phenylacetylglutamine's (PAG) pro-calcifying potential are missing.

METHODS

The effect of TMAO and PAG in vascular calcification was investigated using 120 kidney failure patients undergoing living-donor kidney transplantation (LD-KTx), in an observational, cross-sectional manner. Uremic toxin concentrations were related to coronary artery calcification (CAC) score, epigastric artery calcification score, and markers of established non-traditional risk factors that constitute to the 'perfect storm' that drives early vascular aging in this patient population. Vascular smooth muscle cells were incubated with TMAO or PAG to determine their calcifying effects in vitro and analyse associated pathways by which these toxins may promote vascular calcification.

RESULTS

TMAO, but not PAG, was independently associated with CAC score after adjustment for CKD-related risk factors in kidney failure patients. Neither toxin was associated with epigastric artery calcification score; however, PAG was independently, positively associated with 8-hydroxydeoxyguanosine. Similarly, TMAO, but not PAG, promoted calcium-phosphate deposition in vitro, while both uremic solutes induced oxidative stress.

CONCLUSIONS

In conclusion, our translational data confirm TMAO's pro-calcifying effects, but both toxins induced free radical production detrimental to vascular maintenance. Our findings suggest these gut-derived uremic toxins have different actions on the vessel wall and therapeutically targeting TMAO may help reduce CV-related mortality in CKD.

Elevated plasma phospholipid n-3 docosapentaenoic acid concentrations during hibernation

Factors for initiating hibernation are unknown, but the condition shares some metabolic similarities with consciousness/sleep, which has been associated with n-3 fatty acids in humans. We investigated plasma phospholipid fatty acid profiles during hibernation and summer in free-ranging brown bears (Ursus arctos) and in captive garden dormice (Eliomys quercinus) contrasting in their hibernation patterns. The dormice received three different dietary fatty acid concentrations of linoleic acid (LA) (19%, 36% and 53%), with correspondingly decreased alpha-linolenic acid (ALA) (32%, 17% and 1.4%). Saturated and monounsaturated fatty acids showed small differences between summer and hibernation in both species. The dormice diet influenced n-6 fatty acids and eicosapentaenoic acid (EPA) concentrations in plasma phospholipids. Consistent differences between summer and hibernation in bears and dormice were decreased ALA and EPA and marked increase of n-3 docosapentaenoic acid and a minor increase of docosahexaenoic acid in parallel with several hundred percent increase of the activity index of elongase ELOVL2 transforming C20-22 fatty acids. The highest LA supply was unexpectantly associated with the highest transformation of the n-3 fatty acids. Similar fatty acid patterns in two contrasting hibernating species indicates a link to the hibernation phenotype and requires further studies in relation to consciousness and metabolism.

Interleukin-6-to-Albumin Ratio as a Superior Predictor of Mortality in End-Stage Kidney Disease Patients

INTRODUCTION

In patients with chronic kidney disease (CKD), high interleukin-6 (IL-6) and low albumin circulating concentrations are associated with worse outcomes. We examined the IL-6-to-albumin ratio (IAR) as a predictor of risk of death in incident dialysis patients.

METHODS

In 428 incident dialysis patients (median age 56 years, 62% men, 31% diabetes mellitus, 38% cardiovascular disease [CVD]), plasma IL-6 and albumin were measured at baseline to calculate IAR. We compared the discrimination of IAR with other risk factors for predicting 60-month mortality using receiver operating characteristic curve (ROC) and analyzed the association of IAR with mortality using Cox regression analysis. We divided patients into IAR tertiles and analyzed: (1) cumulative incidence of mortality and the association of IAR with mortality risk in Fine-Gray analysis, taking kidney transplantation as competing risk and (2) the restricted mean survival time (RMST) to 60-month mortality and differences of RMST (∆RMST) between IAR tertiles to describe quantitative differences of survival time.

RESULTS

For all-cause mortality, the area under the ROC curve (AUC) for IAR was 0.700, which was greater than for IL-6 and albumin separately, while for CV mortality, the AUC for IAR (0.658) showed negligible improvement over IL-6 and albumin separately. In Cox regression analysis, IAR was significantly associated with all-cause mortality but not with CV mortality. Both high versus low and middle versus low tertiles of IAR associated with higher risk of all-cause mortality, subdistribution hazard ratio of 2.22 (95% CI 1.40-3.52) and 1.85 (95% CI 1.16-2.95), respectively, after adjusting for age, sex, diabetes mellitus, CVD, smoking, and estimated glomerular filtration rate. ∆RMST at 60 months showed significantly shorter survival time in middle and high IAR tertiles compared with low IAR tertile for all-cause mortality.

CONCLUSIONS

Higher IAR was independently associated with significantly higher all-cause mortality risk in incident dialysis patients. These results suggest that IAR may provide useful prognostic information in patients with CKD.

Low-Plasma Insulin-Like Growth Factor-1 Associates With Increased Mortality in Chronic Kidney Disease Patients With Reduced Muscle Strength

OBJECTIVES

Chronic kidney disease (CKD) leads to metabolic and nutritional abnormalities including resistance to insulin-like growth factor-1 (IGF-1) action, and reduced muscle mass and strength. Low IGF-1 as well as low hand-grip muscle strength (HGS) are independent predictors of increased mortality in CKD patients.

METHODS

In 685 patients (CKD Stage 3-5, median age 58 years; 62% men), baseline measurements of IGF-1, HGS, subjective global assessment (SGA), lean body mass index (LBMI), and metabolic and inflammatory biomarkers potentially linked to IGF-1 were analyzed in relation to mortality during 5 years of follow-up. We compared survival in 4 groups with high or low (cut-offs defined by receiver operating characteristic curve analysis) levels of IGF-1 and HGS.

RESULTS

Patients with low IGF-1 were older; had lower BMI, HGS, and LBMI, were more likely to have diabetes, cardiovascular disease (CVD), and malnutrition (SGA >1); and had high-sensitivity C-reactive protein levels. During 5 years of follow-up, 208 patients died. The mortality rate was highest among patients with Low IGF-1 + Low HGS. In competing-risk regression analysis, Low IGF-1 + Low HGS was independently associated with 2.8 times higher all-cause mortality risk than Low IGF-1 + High HGS, after adjusting for Framingham's CVD risk score, presence of CVD, SGA, dialysis status, high-sensitivity C-reactive protein, albumin, LBMI, and sample time in freezer.

CONCLUSION

Low IGF-1 was associated with increased all-cause mortality in patients who also had low HGS but not in those with high HGS, suggesting that the association of IGF-1 with survival in CKD patients depends on nutritional status.

The effect of high-dose vitamin D supplementation on hepcidin-25 and erythropoiesis in patients with chronic kidney disease

BACKGROUND

Hepcidin is considered to play a central role in the pathophysiology of renal anemia. Recent studies in healthy individuals have demonstrated a suppressive effect of vitamin D (VD) on the expression of hepcidin. In this post-hoc analysis based on a randomized controlled study, we evaluated the effect of supplementing chronic kidney disease (CKD) patients (stage G3-G4) with a high daily dose of native VD on serum levels of hepcidin-25, the hepcidin/ferritin ratio, as well as on markers of erythropoiesis.

METHODS

Patients with CKD stage G3-G4 included in a double blind, randomized, placebo (PBO) controlled study with available hepcidin measurements were analyzed. Study subjects received either 8000 international units (IU) of cholecalciferol daily or PBO for 12 weeks. We evaluated the change in markers of hepcidin expression, erythropoiesis, and iron status from baseline to week 12 and compared the change between the groups.

RESULTS

Eighty five patients completed the study. Calcitriol, but not 25-hydroxyvitamin D (25(OH) D), was inversely correlated with serum levels of hepcidin-25 (rho = -0,38; p =  < 0, 01 and rho = -0,02; p = 0, 89, respectively) at baseline. Supplementation with VD significantly raised the serum concentration of serum 25(OH)D in the treatment group (from 54 (39-71) to 156 (120-190) nmol/L; p =  < 0, 01)) but had no effect on any of the markers of hepcidin, erythropoiesis, or iron status in the entire cohort. However, we did observe an increase in hemoglobin (HB) levels and transferrin saturation (TSAT) as compared to the PBO group in a subgroup of patients with low baseline 25(OH)D levels (< 56 nmol/L). In contrast, in patients with high baseline 25(OH)D values (≥ 56 nmol/L), VD supplementation associated with a decrease in HB levels and TSAT (p = 0,056) within the VD group in addition to a decrease in hepcidin levels as compared to the PBO group.

CONCLUSION

High-dose VD supplementation had no discernible effect on markers of hepcidin or erythropoiesis in the entire study cohort. However, in patients with low baseline 25(OH)D levels, high-dose VD supplementation associated with beneficial effects on erythropoiesis and iron availability. In contrast, in patients with elevated baseline 25(OH)D levels, high-dose VD supplementation resulted in a decrease in hepcidin levels, most likely due to a deterioration in iron status.

Central obesity as assessed by conicity index and a-body shape index associates with cardiovascular risk factors and mortality in kidney failure patients

Background

Anthropometric indices of central obesity, waist circumference (WC), conicity index (CI), and a-body shape index (ABSI), are prognostic indicators of cardiovascular (CV) risk. The association of CI and ABSI with other CV risk indices, markers of nutritional status and inflammation, and clinical outcomes in chronic kidney disease (CKD) stage 5 (CKD5) patients was investigated.

Methods

In a cross-sectional study with longitudinal follow up of 203 clinically stable patients with CKD5 (median age 56 years; 68% males, 17% diabetics, 22% with CV disease, and 39% malnourished), we investigated CI and ABSI and their associations with atherogenic index of plasma (AIP), Framingham CV risk score (FRS), Agatston scoring of coronary artery calcium (CAC) and aortic valve calcium (AVC), handgrip strength (HGS), high sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6). CV events (CVE) and all-cause mortality during up to 10-years follow up were analyzed by multivariate survival analysis of restricted mean survival time (RMST).

Results

Chronic kidney disease patients with middle and highest CI and ABSI tertiles (indicating greater abdominal fat deposition), compared to those with the lowest CI and ABSI tertiles, tended to be older, more often men and diabetic, had significantly higher levels of hsCRP, IL-6, AIP, FRS, CAC and AVC scores. CI and ABSI were positively correlated with CAC, FRS, AIP, hsCRP and IL-6. Both CI and ABSI were negatively correlated with HGS. In age-weighted survival analysis, higher CI and ABSI were associated with higher risk of CVE (Wald test = 4.92, p = 0.027; Wald test = 4.95, p = 0.026, respectively) and all-cause mortality (Wald test = 5.24, p = 0.022; Wald test = 5.19, p = 0.023, respectively). In RMST analysis, low vs. high and middle tertiles of CI and ABSI associated with prolonged CVE-free time and death-free time, and these differences between groups increased over time.

Conclusion

Abdominal fat deposit indices, CI and ABSI, predicted CV outcomes and all-cause mortality, and were significantly associated with the inflammatory status in CKD patients.

Secular trends in incidence and seasonal variation of distal radius fracture among children: A nationwide study based on the Swedish National Patient Register 2002-2016

BACKGROUND AND PURPOSE

Although distal radius fracture (DRF) is the most common fracture type in children, research on its seasonality across different age groups is limited. We investigated secular trends in incidence and seasonal variation of pediatric DRF based on Swedish nationwide population database.

PATIENTS AND METHODS

In this observational study, data for all children aged <18 years in Sweden with DRF defined by ICD-codes were analyzed for each month and each year during 2002-2016 using the Swedish National Patient Register. The general population counts for each age and sex-category were acquired to evaluate population at risk for each period. We calculated the age standardized and sex specific annual incidence rates, seasonal incidence rates, and monthly incidence rates and analyzed the seasonal variation in the mechanisms of injury.

RESULTS

A total of 155,891 DRF cases were identified. The age standardized and sex specific incidence rate was 531 (95%CI 528-533) per 100,000 patient years at risk. Fracture risk was highest during summer and lowest in the winter. The highest seasonal variation was observed among boys 2- < 5 years. The crude incidence rate and the age-standardized incidence rates in winter significantly decreased between 2002 and 2016 (annual percentage change, -2 %).

INTERPRETATION

We found significant seasonal variation in DRF among all age groups in Swedish children. The findings can help in developing strategies to prevent fractures as well as in allocating medical and social resources.

First-year mortality in incident dialysis patients: results of the Peridialysis study

Background

Controversy surrounds which factors are important for predicting early mortality after dialysis initiation (DI). We investigated associations of predialysis course and circumstances affecting planning and execution of DI with mortality following DI.

Methods

Among 1580 patients participating in the Peridialysis study, a study of causes and timing of DI, we registered features of predialysis course, clinical and biochemical data at DI, incidence of unplanned suboptimal DI, contraindications to peritoneal dialysis (PD) or hemodialysis (HD), and modality preference, actual choice, and cause of modality choice. Patients were followed for 12 months or until transplantation. A flexible parametric model was used to identify independent factors associated with all-cause mortality.

Results

First-year mortality was 19.33%. Independent factors predicting death were high age, comorbidity, clinical contraindications to PD or HD, suboptimal DI, high eGFR, low serum albumin, hyperphosphatemia, high C-reactive protein, signs of overhydration and cerebral symptoms at DI. Among 1061 (67.2%) patients who could select dialysis modality based on personal choice, 654 (61.6%) chose PD, 368 (34.7%) center HD and 39 (3.7%) home HD. The 12-months survival did not differ significantly between patients receiving PD and in-center HD.

Conclusions

First-year mortality in incident dialysis patients was in addition to high age and comorbidity, associated with clinical contraindications to PD or HD, clinical symptoms, hyperphosphatemia, inflammation, and suboptimal DI. In patients with a “free” choice of dialysis modality based on their personal preferences, PD and in-center HD led to broadly similar short-term outcomes.

Scoring of medial arterial calcification predicts cardiovascular events and mortality after kidney transplantation

BACKGROUND

Progression of vascular calcification causes cardiovascular disease, which is the most common cause of death in chronic kidney failure and after kidney transplantation (KT). The prognostic impact of the extent of medial vascular calcification at KT is unknown.

METHODS

In this prospective cohort study, we investigated the impact of medial calcification compared to a mix of intimal and medial calcification represented by coronary artery calcification (CAC score) and aortic valve calcification in 342 patients starting on kidney failure replacement therapy. The primary outcomes were cardiovascular events (CVE) and death. The median follow-up time was 6.4 years (interquartile range 3.7-9.6 years). Exposure was CAC score and arteria epigastrica medial calcification scored as none, mild, moderate, or severe by a pathologist at time of KT (n = 200). We divided the patients according to kidney failure replacement therapy during follow-up, that is, living donor KT, deceased donor KT, or dialysis.

RESULTS

Moderate to severe medial calcification in the arteria epigastrica was associated with higher mortality (p = 0.001), and the hazard ratio for CVE was 3.1 (95% confidence interval [CI] 1.12-9.02, p < 0.05) compared to no or mild medial calcification. The hazard ratio for 10-year mortality in the dialysis group was 33.6 (95% CI, 10.0-113.0, p < 0.001) compared to living donor recipients, independent of Framingham risk score and prevalent CAC.

CONCLUSION

Scoring of medial calcification in the arteria epigastrica identified living donor recipients as having 3.1 times higher risk of CVE, independent of traditional risk factors. The medial calcification score could be a reliable method to identify patients with high and low risk of CVE and mortality following KT.

Pentraxin-3 - a potential biomarker in ANCA-associated vasculitis

OBJECTIVE

The aim of this study was to investigate pentraxin-3 (PTX3) as a potential biomarker of inflammatory activity in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) at baseline and 6 month follow-up in a longitudinal cohort.

METHOD

Plasma PTX3 levels were measured in 79 newly diagnosed or relapsing AAV patients at baseline and 6 month follow-up, and in 23 healthy controls. Urinary PTX3 levels were measured in 34 of the patients. C-reactive protein (CRP), creatinine, and albuminuria were measured and the cumulative glucocorticoid dose at inclusion was calculated. The Birmingham Vasculitis Activity Score (BVAS) was assessed at baseline and follow-up.

RESULTS

Plasma PTX3 levels were significantly higher at baseline than at 6 months (2.85 vs 1.23 ng/mL, p < 0.001). Plasma and urinary PTX3 levels correlated with BVAS at baseline (ρ = 0.45, p < 0.001, and ρ = 0.49, p = 0.008, respectively). A significant correlation between both plasma and urinary PTX3 levels and estimated glomerular filtration rate and albuminuria was found. However, there was no correlation between plasma and urinary PTX3 levels. At baseline, plasma and urinary PTX3 levels were significantly higher in patients with kidney involvement. PTX3 levels did not correlate with CRP, nor was there a correlation between CRP levels and BVAS at baseline.

CONCLUSION

Plasma and urinary PTX3 seem to reflect disease activity in AAV better than the commonly used CRP. PTX3 may have a potential role as a biomarker in monitoring disease activity in AAV patients, particularly in patients with kidney involvement.

Longitudinal genome-wide DNA methylation changes in response to kidney failure replacement therapy

Chronic kidney disease (CKD) is an emerging public health priority associated with high mortality rates and demanding treatment regimens, including life-style changes, medications or even dialysis or renal transplantation. Unavoidably, the uremic milieu disturbs homeostatic processes such as DNA methylation and other vital gene regulatory mechanisms. Here, we aimed to investigate how dialysis or kidney transplantation modifies the epigenome-wide methylation signature over 12 months of treatment. We used the Infinium HumanMethylation450 BeadChip on whole blood samples from CKD-patients undergoing either dialysis (n = 11) or kidney transplantation (n = 12) and 24 age- and sex-matched population-based controls. At baseline, comparison between patients and controls identified several significant (P_FDR < 0.01) CpG methylation differences in genes with functions relevant to inflammation, cellular ageing and vascular calcification. Following 12 months, the global DNA methylation pattern of patients approached that seen in the control group. Notably, 413 CpG sites remained differentially methylated at follow-up in both treatment groups compared to controls. Together, these data indicate that the uremic milieu drives genome-wide methylation changes that are partially reversed with kidney failure replacement therapy. Differentially methylated CpG sites unaffected by treatment may be of particular interest as they could highlight candidate genes for kidney disease per se.

The Novel Bone Alkaline Phosphatase Isoform B1x Is Associated with Improved 5-Year Survival in Chronic Kidney Disease

Circulating alkaline phosphatase (ALP) is an independent cardiovascular risk marker. Serum bone ALP (BALP) isoforms indicate bone turnover and comprise approximately 50% of total circulating ALP. In chronic kidney disease (CKD), mortality is highest in patients with increased ALP and BALP and low bone turnover. However, not all low bone turnover states are associated with increased mortality. Chronic inflammation and oxidative stress, features of protein energy wasting syndrome, induce cardiovascular BALP activity and fibro-calcification, while bone turnover is suppressed. Circulating BALP isoform B1x is associated with low ALP and low bone turnover and has been exclusively detected in CKD. We investigated the association of serum B1x with survival, abdominal aortic calcification (AAC) score, and aortic pulse wave velocity (PWV) in CKD. Serum ALP, BALP isoforms, parathyroid hormone (PTH), PWV, and AAC were measured repeatedly over 2 years in 68 prevalent dialysis patients. Mortality was assessed after 5 years. B1x was detected in 53 patients. A competing risk analysis revealed an association of B1x with improved 5-year survival; whereas, baseline PWV, but not AAC score, predicted mortality. However, PWV improved in 26 patients (53%), and B1x was associated with variation of PWV over time (p = 0.03). Patients with B1x had lower PTH and total ALP, suggesting an association with lower bone turnover. In conclusion, B1x is associated with time-varying PWV, lower circulating ALP, and improved survival in CKD, and thus may be an indicator of a reduced cardiovascular risk profile among patients with low bone turnover.

Increased Monocyte/Lymphocyte Ratio as Risk Marker for Cardiovascular Events and Infectious Disease Hospitalization in Dialysis Patients

Introduction

In dialysis patients, cardiovascular disease (CVD) and infectious disease contribute to poor clinical outcomes. We investigated if a higher monocyte/lymphocyte ratio (MLR) is associated with an increased risk of CVD events and infectious disease hospitalizations in incident dialysis patients.

Methods

In an ongoing observational prospective cohort study, 132 Japanese dialysis patients (age 58.7 ± 11.7 years; 70% men) starting dialysis therapy were enrolled and followed up for a median of 48.7 months. Laboratory biomarkers, including white blood cell count and its differential count, were determined at baseline. Event-free time and relative risks (RRs) were calculated using the Kaplan-Meier curves and Cox models, respectively.

Results

When divided into 2 groups according to median MLR (0.35 [range, 0.27–0.46]), the periods without CVD events were significantly shorter in the high MLR group than in the low MLR group (log-rank test = 5.60, p = 0.018). The RR of CVD events, after adjusting for age, sex, and diabetes, was 2.43 (1.22–4.84) in the high MLR group compared to the low MLR group. The periods without infections requiring hospitalization were also shorter (log-rank test = 4.16, p = 0.041). The RR of infections requiring hospitalization was 1.98 (1.02–3.83) after the same adjustments. The number of CVD events was higher in the high MLR group (18.6 events per 100 person-years at risk [pyr]) than the low MLR group (11.1 events per 100 pyr). The duration of infectious disease hospitalization was longer in the high MLR group (6.3 days per pyr) than in the low MLR group (2.8 days per pyr).

Conclusion

A higher MLR is associated with increased risks of both CVD events and infectious disease hospitalization in dialysis patients.

Metacarpal bone diameter increases constantly in adult females, but escalated resorption of the inner surface at menopause explains the observed decreased bone mineral density at digital X-ray radiogrammetry

OBJECTIVE

To assess how bone morphology and mineralization changes with age, in women by digital X-ray radiogrammetry (DXR). DXR has potential as a screening tool for osteoporosis, as it can evaluate bone mineralization similarly to dual-energy X-ray absorptiometry.

METHODS

The nondominant hand was analyzed with DXR in 13,285 women ages 40-74 years undergoing mammography. 1,556 women attended two consecutive examinations with 18 to 24 months interval. Changes in bone parameters were calculated and compared in 5-year age groups. Regression analysis and ANOVA tests were performed.

RESULTS

Univariate linear regression showed no significant difference in age or bone size between the groups with single or consecutive measurements. In the group with consecutive measurements, the average inner diameter (DXR-ID) of the metacarpals significantly increased with age from 0.38 cm in the 40-45 years age span to 0.47 cm in the 65+ age group (P < 0.001), whereas DXR bone mineral density (DXR-BMD) decreased from 0.59 g/cm2 to 0.50 g/cm2 in the same age groups (P < 0.001). Intraindividual measurements showed a fourfold increase in yearly DXR-ID increase and concurrent DXR-BMD loss between 50 and 59 years of age (P < 0.001). The outer diameter only increased significantly between the youngest and oldest age group (P < 0.001).

CONCLUSIONS

The faster decrease in DXR-BMD observed during and after menopause is caused by resorption of the inner cortical surface, not matched by outer diameter increase. We speculate that most bones in the human body grow in the same pattern as observed in the metacarpals, partly explaining decreasing BMD at DXR and dual-energy X-ray absorptiometry.

Time-dependent lipid profile inversely associates with mortality in hemodialysis patients - independent of inflammation/malnutrition

BACKGROUND

Patients with end-stage kidney disease have an extremely high cardiovascular mortality rate, but there is a paradoxical relationship between lipid profile and survival in haemodialysis patients. To investigate whether inflammation/malnutrition confounds the associations between lipids and mortality, we studied a full lipid profile comprising of five clinically well-established lipid parameters and its associations with mortality in a large, multinational European cohort with a median follow-up >3 years.

METHODS

The association between quartiles of total, high-density lipoprotein (HDL), non-HDL, low-density lipoprotein (LDL) cholesterol, as well as triglyceride, levels and the end-points of all-cause, cardiovascular and non-cardiovascular mortality was assessed in a cohort of 5,382 incident, adult haemodialysis patients from >250 Fresenius Medical Care dialysis centres out of 14 participating countries using baseline and time-dependent Cox models. Analyses were fully adjusted and stratified for inflammation/malnutrition status and other patient-level variables.

RESULTS

Time-dependent quartiles of total, HDL, non-HDL and LDL cholesterol were inversely associated with the hazard for all-cause, cardiovascular and non-cardiovascular mortality. Compared with the lowest quartile of the respective lipid parameter, hazard ratios of other quartiles were <0.86. Similar, albeit weaker, associations were found with baseline lipid profile and mortality. Neither time-dependent nor baseline associations between lipid profile and mortality were affected by inflammation/malnutrition, statin use or geography.

CONCLUSIONS

Baseline and time-dependent lipid profile are inversely associated with mortality in a large, multicentre cohort of incident haemodialysis patients. Inflammation/malnutrition is not a confounder nor effect modificator of the associations between lipid profile and mortality in European haemodialysis patients.

Observational study of risk factors associated with clinical outcome among elderly kidney transplant recipients in Sweden - a decade of follow-up

BACKGROUND

Kidney transplantation (Ktx) in elderly has become increasingly accepted worldwide despite their higher burden of comorbidities. We investigated important risk factors affecting long-term patient and graft survival.

METHODS

We included all (n=747) Ktx patients >60 years from 2000 to 2012 in Sweden. Patients were age-stratified; 60-64, 65-69 and >70 years. Follow-up time was up to 10 years (median 7.9 years, 75% percentile >10 years). Primary outcome was 10-year patient survival in age-stratified groups. Secondary outcomes were 5- year patient and graft-survival in age-stratified groups and the impact of risk factors including Charlson comorbidity index on patient and graft-survival.

RESULTS

Mortality was higher in patients >70 years, after 10 years (HR 1.94; 95% CI 1.24-3.04; p=0.004). Males had a higher 10-year risk of death (HR 1.39; CI 95% 1.04-1.86; p=0.024). Five-year patient survival did not differ between age-groups. In multivariate Cox analysis (n=500) hazard ratio for 10-year mortality was 4.6 in patients with Charlson comorbidity index ≥7 vs <4 (95% CI 2.42-8.62; p=0.0001) CONCLUSION: Higher Charlson comorbidity index identified ESKD patients with 4.6 times higher risk of death after Ktx. We suggest that this index should be used as a part of the pre-operative evaluation in elderly.

Secular trends in hip fracture incidence and subsequent mortality in dialysis patients and the general population in Sweden

BACKGROUND

Declining trends of hip fracture incidence in dialysis patients were reported from USA and Japan while studies from Europe are lacking. We investigated trends in hip fracture incidence and subsequent mortality in Swedish dialysis patients, comparing with the Swedish general population.

METHODS

We used the population-based Swedish national database of fractures and the Swedish National Renal Registry to retrieve data on hip fractures incidence and subsequent mortality for years 2007-2016. Trends for age-standardized hip fracture incidence rate (ASR_{hip fracture}) and age-standardized 30-day (ASMR_30day) and 180-day (ASMR_180day) post-hip fracture mortality rate in Swedish general population were evaluated by joinpoint regression analysis. Standardized incidence ratios of hip fracture (SIR) and standardized mortality ratios (SMR) were calculated for Swedish dialysis patients.

RESULTS

In the general population, ASR_{hip fracture} declined significantly: in women from 2007 and in men from 2009. In dialysis patients, SIR was 3-5 times higher compared to the general population and declined over time in women but not in men. In general population, mortality (ASMR_30day and ASMR_180day) declined significantly in women and men. In dialysis patients, post-fracture mortality (SMR, mainly for 180-day mortality) remained two-fold higher than in general population with no consistent trend towards improvement.

CONCLUSIONS

Hip fracture incidence and subsequent mortality fell among women and men in the Swedish general population. In dialysis patients, hip fracture incidence declined in women but not in men while post-fracture mortality did not improve, and the incidence and subsequent mortality remained 3 to 5-fold and 2-fold higher than in the general population.

Sparing effect of peritoneal dialysis vs hemodialysis on BMD changes and its impact on mortality

INTRODUCTION

Bone loss in end stage renal disease (ESRD) patients associates with fractures, vascular calcification, cardiovascular disease (CVD) and increased mortality. We investigated factors associated with changes of bone mineral density (ΔBMD) during the initial year on dialysis therapy and associations of ΔBMD with subsequent mortality in ESRD patients initiating dialysis.

MATERIALS AND METHODS

In 242 ESRD patients (median age 55 years, 61% men) starting dialysis with peritoneal dialysis (PD; n = 138) or hemodialysis (HD; n = 104), whole-body dual-energy X-ray absorptiometry (DXA), body composition, nutritional status and circulating biomarkers were assessed at baseline and 1 year after dialysis start. We used multivariate linear regression analysis to determine factors associated with ΔBMD, and fine and gray competing risk analysis to determine associations of ΔBMD with subsequent mortality risk.

RESULTS

BMD decreased significantly in HD patients (significant reductions of BMD_total and BMD_{leg, trunk, rib, pelvis and spine}) but not in PD patients. HD compared to PD therapy associated with negative changes in BMD_{total (β=- 0.15)}, BMD_{head (β=- 0.14)}, BMD_{leg (β=- 0.18)} and BMD_{trunk (β=- 0.16)}. Better preservation of BMD associated with significantly lower all-cause mortality for ΔBMD_total (sub-hazard ratio, sHR, 0.91), ΔBMD_head (sHR 0.91) and ΔBMD_leg (sHR 0.92), while only ΔBMD_head (sHR 0.92) had a beneficial effect on CVD-mortality.

CONCLUSIONS

PD had beneficial effect compared with HD on BMD changes during first year of dialysis therapy. Better preservation of BMD, especially in bone sites rich in cortical bone, associated with lower subsequent mortality. BMD in cortical bone may have stronger association with clinical outcome than BMD in trabecular bone.

Functional vitamin K insufficiency, vascular calcification and mortality in advanced chronic kidney disease: A cohort study

Patients with chronic kidney disease (CKD) suffer from vitamin K deficiency and are at high risk of vascular calcification (VC) and premature death. We investigated the association of functional vitamin K deficiency with all-cause mortality and whether this association is modified by the presence of VC in CKD stage 5 (CKD G5). Plasma dephosphorylated-uncarboxylated matrix Gla-protein (dp-ucMGP), a circulating marker of functional vitamin K deficiency, and other laboratory and clinical data were determined in 493 CKD G5 patients. VC was assessed in subgroups by Agatston scoring of coronary artery calcium (CAC) and aortic valve calcium (AVC). Backward stepwise regression did not identify dp-ucMGP as an independent determinant of VC. During a median follow-up of 42 months, 93 patients died. Each one standard deviation increment in dp-ucMGP was associated with increased risk of all-cause mortality (sub-hazard ratio (sHR) 1.17; 95% confidence interval, 1.01-1.37) adjusted for age, sex, cardiovascular disease, diabetes, body mass index, inflammation, and dialysis treatment. The association remained significant when further adjusted for CAC and AVC in sub-analyses (sHR 1.22, 1.01-1.48 and 1.27, 1.01-1.60, respectively). In conclusion, functional vitamin K deficiency associates with increased mortality risk that is independent of the presence of VC in patients with CKD G5.

Incidence of Fractures Before and After Dialysis Initiation

Fractures are common in dialysis patients, but little is known about the trajectory of incidence rates of different types of fractures before and after dialysis initiation. To address this, we investigated the incidence of major fractures before and after dialysis initiation. We performed a retrospective statistical analysis using the Swedish Renal Registry of 9041 incident dialysis patients (median age 67 years, 67% men) starting dialysis 2005 through 2015 to identify major fractures (hip, spine, humerus, and forearm) occurring during the dialysis transition period from 1 year before until 1 year after dialysis initiation. Using flexible parametric hazard models and the Fine-Gray model, we estimated adjusted fracture incidence rates and predictors of major fractures. We identified 361 cases with primary diagnosis of major fracture, of which 196 (54%) were hip fractures. The crude incidence rate of major fractures before dialysis initiation was 17 per 1000 patient-years (n = 157) and after dialysis initiation it was 24 per 1000 patient-years (n = 204). The adjusted incidence rate of major fractures began to increase 6 months before dialysis initiation, and then stabilized at a higher rate after 1 year. The adjusted incidence rate of hip fractures started to increase sharply 3 months before dialysis initiation, peaked at initiation, and declined thereafter. In contrast, the adjusted incidence rate of non-hip fractures was stable during the transition period and gradually increased over time. Higher age, female sex, and history of previous major fractures were associated with increased fracture incidence both before and after dialysis initiation. We conclude that the incidence of major fractures, especially hip fractures, start to rise 6 months before initiation of dialysis therapy, indicating that heightened surveillance with implementation of preventive measures to avoid fractures is warranted during the transition period to dialysis. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Inverse J-shaped relation between coronary arterial calcium density and mortality in advanced chronic kidney disease

BACKGROUND

The coronary artery calcium (CAC) score from cardiac computed tomography (CT) is a composite of CAC volume and CAC density. In the general population, CAC volume is positively and CAC density inversely associated with cardiovascular disease (CVD) events, implying that decreased CAC density reflects atherosclerotic plaque instability. We analysed associations of CAC indices with mortality risk in patients with end-stage renal disease [chronic kidney disease Stage 5 (CKD5)].

METHODS

In 296 CKD5 patients undergoing cardiac CT (median age 55 years, 67% male, 19% diabetes, 133 dialysed), the Framingham risk score (FRS), presence of CVD and protein-energy wasting (PEW; subjective global assessment) and high-sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6) were determined at baseline. During follow-up for a median of 35 months, 51 patients died and 75 patients underwent renal transplantation. All-cause mortality risk was analysed with competing-risk regression models. Vascular calcification was analysed in biopsies of the arteria epigastrica inferior in 111 patients.

RESULTS

Patients in the middle tertile of CAC density had the highest CAC score, CAC volume, age, CVD, PEW, FRS, hsCRP and IL-6. In competing risk analysis, the middle {subhazard ratio [sHR] 10.7 [95% confidence interval (CI) 2.0-57.3]} and high [sHR 8.9 (95% CI 1.5-51.8)] tertiles of CAC density associated with increased mortality, independent of CAC volume. The high tertile of CAC volume, independent of CAC density, associated with increased mortality [sHR 8.9 (95% CI 1.5-51.8)]. Arterial media calcification was prominent and associated with CAC volume and CAC density.

CONCLUSIONS

In CKD5, mortality increased linearly with higher CAC score and CAC volume whereas for CAC density an inverse J-shaped pattern was observed, with the crude mortality rate being highest for the middle tertile of CAC density. CAC volume and CAC density were associated with the extent of arterial media calcification.

Insights in the regulation of trimetylamine N-oxide production using a comparative biomimetic approach suggest a metabolic switch in hibernating bears

Experimental studies suggest involvement of trimethylamine N-oxide (TMAO) in the aetiology of cardiometabolic diseases and chronic kidney disease (CKD), in part via metabolism of ingested food. Using a comparative biomimetic approach, we have investigated circulating levels of the gut metabolites betaine, choline, and TMAO in human CKD, across animal species as well as during hibernation in two animal species. Betaine, choline, and TMAO levels were associated with renal function in humans and differed significantly across animal species. Free-ranging brown bears showed a distinct regulation pattern with an increase in betaine (422%) and choline (18%) levels during hibernation, but exhibited undetectable levels of TMAO. Free-ranging brown bears had higher betaine, lower choline, and undetectable TMAO levels compared to captive brown bears. Endogenously produced betaine may protect bears and garden dormice during the vulnerable hibernating period. Carnivorous eating habits are linked to TMAO levels in the animal kingdom. Captivity may alter the microbiota and cause a subsequent increase of TMAO production. Since free-ranging bears seems to turn on a metabolic switch that shunts choline to generate betaine instead of TMAO, characterisation and understanding of such an adaptive switch could hold clues for novel treatment options in burden of lifestyle diseases, such as CKD.

Fractures after kidney transplantation: Incidence, predictors, and association with mortality

BACKGROUND

Major fractures (MF) are associated with increased mortality in the general population and represent an even higher risk in patients with chronic kidney disease. We investigated incidence, predictors and clinical outcomes associated with first MF (MF_first) following kidney transplantation (KT).

METHODS

We used the Swedish National Renal Registry of 3992 first KT recipients (2005-2016) (median age 53 years, 65% men) and identified all MF_first in hip, spine, humerus and forearm following KT. We estimated incidence rates and predictors of MF_first using flexible parametric hazard models and Fine-Gray analysis accounting for competing risk of death, and risk of all-cause mortality following MF_first using Cox proportional hazards models with fracture as time-varying exposure.

RESULTS

During median follow-up of 4.8 years (IQR 2.2-7.9 years), there were 279 fractures of which 139 were forearm fractures. The crude incidence rate of MF_first (n = 279) was 13.5/1000 patient-years and that of hip fractures (n = 69) 3.4/1000 patient-years. The multivariate-adjusted fracture incidence rates were highest during the first 6 months following KT, and 86% higher in women than in men. High age, female sex, previous history of MF, diabetes nephropathy, pretransplant dialysis therapy and acute rejection were associated with increased risk for MF_first, whereas pre-emptive KT was associated with lower risk of MF_first. Spline curves showed markedly higher impact of higher age on risk of MF_first in women than in men. MF_first (n = 279) independently predicted increased all-cause mortality risk (hazard ratio, HR, 1.78(95%CI 1.35-2.36)). Among MF_first, with humerus fracture as reference, hip fracture (HR, 4.68(95%CI 1.56-14.06)) and spine fracture (HR, 4.02(95%CI 1.19-13.54)), but not forearm fracture (HR, 1.17 (95%CI 0.38-3.53)), were associated with increased all-cause mortality risk.

CONCLUSIONS

The initial 6 months following kidney transplantation is a high-risk period for MF. Among MF, hip fracture and spine fracture associate with substantially increased all-cause mortality risk.

Fractures and their sequelae in non-dialysis-dependent chronic kidney disease: the Stockholm CREAtinine Measurement project

Introduction

People undergoing maintenance dialysis are at high risk for fractures, but less is known about fracture incidence and associated outcomes in earlier stages of chronic kidney disease (CKD).

Methods

We conducted an observational analysis from the Stockholm Creatinine Measurement project, a Swedish health care utilization cohort during 2006–11. We identified all adults with confirmed CKD Stages 3–5 and no documented history of fractures and extracted information on comorbid history, ongoing medication, cardiovascular events and death. We studied incidence rates of fractures (overall and by location), with the estimated glomerular filtration rate (eGFR) as time-dependent exposure. We then studied hazard ratios [HRs and 95% confidence intervals (CIs)] for the events of death and major adverse cardiac events (MACE) using Cox regression with fracture as time-varying exposure.

Results

We identified 68 764 individuals with confirmed CKD (mean age 79 years, 56% women). During a median follow-up of 2.7 years, 9219 fractures occurred, of which 3105 were hip fractures. A more severe CKD stage was associated with a higher risk of fractures, particularly hip fractures: compared with CKD Stage 3a, the adjusted HR was 1.10 (95% CI 1.02–1.19), 1.32 (1.17–1.49) and 2.47 (1.94–3.15) for CKD Stage 3b, 4 and 5, respectively. Spline curves suggested a linear association with fracture risk with an eGFR <30 mL/min/1.73 m². Compared with non-fracture periods, incident fracture was associated with a 4-fold increased mortality within 90 days [HR 4.21 (95% CI 3.95–4.49)]. The risk remained elevated beyond 90 days [HR 1.47 (95% CI 1.40–1.54)] and was stronger after hip fractures. Post-fracture MACE risk was also highest in the first 90 days [HR 4.02 (95% CI 3.73–4.33)], particularly after hip fractures, and persisted beyond 90 days [HR 1.20 (95% CI 1.10–1.30)].

Conclusion

Our findings highlight the commonness of fractures and the increased risk for subsequent adverse outcomes in CKD patients. These results may inform clinical decisions regarding post-fracture clinical surveillance and fracture prevention strategies.

Pro-neurotensin depends on renal function and is related to all-cause mortality in chronic kidney disease

BACKGROUND

Patients with chronic kidney disease (CKD) have a high risk of premature cardiovascular diseases (CVD) and show increased mortality. Pro-neurotensin (Pro-NT) was associated with metabolic diseases and predicted incident CVD and mortality. However, Pro-NT regulation in CKD and its potential role linking CKD and mortality have not been investigated, so far.

METHODS

In a central lab, circulating Pro-NT was quantified in three independent cohorts comprising 4715 participants (cohort 1: patients with CKD; cohort 2: general population study; and cohort 3: non-diabetic population study). Urinary Pro-NT was assessed in part of the patients from cohort 1. In a 4th independent cohort, serum Pro-NT was further related to mortality in patients with advanced CKD. Tissue-specific Nts expression was further investigated in two mouse models of diabetic CKD and compared to non-diabetic control mice.

RESULTS

Pro-NT significantly increased with deteriorating renal function (P < 0.001). In meta-analysis of cohorts 1-3, Pro-NT was significantly and independently associated with estimated glomerular filtration rate (P ≤ 0.002). Patients in the middle/high Pro-NT tertiles at baseline had a higher all-cause mortality compared to the low Pro-NT tertile (Hazard ratio: 2.11, P = 0.046). Mice with severe diabetic CKD did not show increased Nts mRNA expression in different tissues compared to control animals.

CONCLUSIONS

Circulating Pro-NT is associated with impaired renal function in independent cohorts comprising 4715 subjects and is related to all-cause mortality in patients with end-stage kidney disease. Our human and rodent data are in accordance with the hypotheses that Pro-NT is eliminated by the kidneys and could potentially contribute to increased mortality observed in patients with CKD.

Bone mineral density and mortality in end-stage renal disease patients

Osteoporosis characterized by low bone mineral density (BMD) as assessed by dual-energy X-ray absorptiometry (DXA) is common among end-stage renal disease (ESRD) patients and associates with high fracture incidence and high all-cause mortality. This is because chronic kidney disease-mineral bone disorders (CKD-MBDs) promote not only bone disease (osteoporosis and renal dystrophy) but also vascular calcification and cardiovascular disease. The disturbed bone metabolism in ESRD leads to 'loss of cortical bone' with increased cortical porosity and thinning of cortical bone rather than to loss of trabecular bone. Low BMD, especially at cortical-rich bone sites, is closely linked to CKD-MBD, vascular calcification and poor cardiovascular outcomes. These effects appear to be largely mediated by shared mechanistic pathways via the 'bone-vascular axis' through which impaired bone status associates with changes in the vascular wall. Thus, bone is more than just the scaffolding that holds the body together and protects organs from external forces but is-in addition to its physical supportive function-also an active endocrine organ that interacts with the vasculature by paracrine and endocrine factors through pathways including Wnt signalling, osteoprotegerin (OPG)/receptor activator of nuclear factor-κB (RANK)/RANK ligand system and the Galectin-3/receptor of advanced glycation end products axis. The insight that osteogenesis and vascular calcification share many similarities-and the knowledge that vascular calcification is a cell-mediated active rather than a passive mineralization process-suggest that low BMD and vascular calcification ('vascular ossification') to a large extent represent two sides of the same coin. Here, we briefly review changes of BMD in ESRD as observed using different DXA methods (central and whole-body DXA) at different bone sites for BMD measurements, and summarize recent knowledge regarding the relationships between 'low BMD' and 'fracture incidence, vascular calcification and increased mortality' in ESRD patients, as well as potential 'molecular mechanisms' underlying these associations.

Sevelamer Use in End-Stage Kidney Disease (ESKD) Patients Associates with Poor Vitamin K Status and High Levels of Gut-Derived Uremic Toxins: A Drug-Bug Interaction?

Gut microbial metabolism is not only an important source of uremic toxins but may also help to maintain the vitamin K stores of the host. We hypothesized that sevelamer therapy, a commonly used phosphate binder in patients with end-stage kidney disease (ESKD), associates with a disturbed gut microbial metabolism. Important representatives of gut-derived uremic toxins, including indoxyl sulfate (IndS), p-Cresyl sulfate (pCS), trimethylamine N-oxide (TMAO), phenylacetylglutamine (PAG) and non-phosphorylated, uncarboxylated matrix-Gla protein (dp-ucMGP; a marker of vitamin K status), were analyzed in blood samples from 423 patients (65% males, median age 54 years) with ESKD. Demographics and laboratory data were extracted from electronic files. Sevelamer users (n = 172, 41%) were characterized by higher phosphate, IndS, TMAO, PAG and dp-ucMGP levels compared to non-users. Sevelamer was significantly associated with increased IndS, PAG and dp-ucMGP levels, independent of age, sex, calcium-containing phosphate binder, cohort, phosphate, creatinine and dialysis vintage. High dp-ucMGP levels, reflecting vitamin K deficiency, were independently and positively associated with PAG and TMAO levels. Sevelamer therapy associates with an unfavorable gut microbial metabolism pattern. Although the observational design precludes causal inference, present findings implicate a disturbed microbial metabolism and vitamin K deficiency as potential trade-offs of sevelamer therapy.

Different subclasses and isotypes of antibodies against phosphorylcholine in haemodialysis patients: association with mortality

The risk of premature death is high among patients on haemodialysis (HD patients). We previously determined that immunoglobulin (Ig)M antibodies against phosphorylcholine (anti‐PC) are negatively associated with increased risk of cardiovascular disease (CVD), atherosclerosis, some autoimmune diseases and mortality among HD patients in this cohort. Here, we also study other subclasses and isotypes of anti‐PC in HD patients in relation to mortality, inflammation and gender. The study group is a cohort of 209 prevalent HD patients [median age = 66 years, interquartile range (IQR) = 51–74], vintage time = 29 months (IQR = 15–58; 56% men) with a mean follow‐up period of 41 months (IQR = 20–60). Fifty‐six per cent were men. We also divided patients into inflamed C‐reactive protein (CRP) > 5·6 mg/ml and non‐inflamed CRP. Antibody levels were determined by in‐house enzyme‐linked immunosorbent assay. IgG1 anti‐PC below median was significantly associated with increased all‐cause mortality (after adjustment for confounders: P = 0·02), while IgG, IgA and IgG2 anti‐PC were not associated with this outcome. Among non‐inflamed patients, IgM and IgG1 anti‐PC were significantly associated with mortality (P = 0·047 and 0·02). IgG1 anti‐PC was significantly associated with mortality among men (P = 0·03) and trending among women (P = 0·26). IgM (as previously reported) and IgG1 anti‐PC are negatively associated with survival among HD patients and non‐inflamed HD patients, but among inflamed patients there were no associations. IgG, IgA or IgG2 anti‐PC were not associated with survival in these groups and subgroups. Further studies are needed to determine if raising anti‐PC levels, especially IgM and IgG1 anti‐PC, through immunization is beneficial.

High alkaline phosphatase and low intact parathyroid hormone associate with worse clinical outcome in peritoneal dialysis patients

OBJECTIVE

Alkaline phosphatase (ALP) is used as a biomarker to monitor the chronic kidney disease-mineral bone disorder (CKD-MBD) and high levels of parathyroid hormone (PTH) that were reported to be related to increased mortality in CKD patients. Therefore, we conducted this longitudinal cohort study to evaluate the relations between ALP and intact PTH (iPTH) and the associations with all-cause and cardiovascular mortality in peritoneal dialysis (PD) patients.

METHODS

In 1276 incident PD patients (median age 50 years, 56% males), baseline serum ALP, iPTH, and metabolic biomarkers potentially linked to CKD-MBD were analyzed in relation to mortality during follow-up period of up to 60 months. All-cause and cardiovascular mortality risk of ALP and iPTH were analyzed with competing-risks regression models with transplantation as competing risk adjusting for all covariates.

RESULTS

After adjustments for confounders by logistic regression model, older age, higher change level to levels of iPTH, S-albumin, calcium, alanine transaminase (ALT), and lower level of phosphorus were associated with higher ALP level (>79 U/L), and female gender, non-diabetes mellitus, younger age, lower calcium, higher ALT, total bilirubin, phosphorus, and ALP were associated with higher iPTH level (>300 pg/mL). During 60 months (median 44 months) of follow-up, the all-cause mortality rate was 16%, and 91 (46%) of the 199 deaths were caused by cardiovascular disease. In competing-risks regression analysis, "high ALP + low iPTH" was independently associated with all-cause and cardiovascular mortality after adjustment for age, gender, presence of diabetes, and cardiovascular disease, the calendar year of recruitment and vitamin D therapy in PD patients. The subhazard ratio (sHR) of group "high ALP + low iPTH" was 1.96 times and 3.35 times higher than sHR of group "low ALP + high iPTH" for all-cause mortality and cardiovascular mortality, respectively.

CONCLUSIONS

The combination of high ALP and low iPTH was independently associated with increased all-cause and cardiovascular mortality in PD patients, suggesting that ALP and iPTH have the potential to predict clinical outcomes and might be useful risk assessment tools in PD patients. Further studies exploring the observed association between combination of ALP with iPTH and mortality are warranted.

Matrix Gla protein is an independent predictor of both intimal and medial vascular calcification in chronic kidney disease

Matrix Gla protein (MGP) is a potent inhibitor of vascular calcification (VC) and requires carboxylation by vitamin K to exert calcification inhibition. Chronic kidney disease (CKD) patients undergo early vascular aging often involving extensive VC. The present cross-sectional study investigated the association between circulating dp-ucMGP levels, MGP expression in vascular tissue and MGP polymorphisms. In 141 CKD stage 5 patients, CAC score was significantly increased in the highest tertile of dp-ucMGP (p = 0.002), and a high medial VC score was associated with elevated dp-ucMGP levels. MGP vascular expression was associated with increased circulating dp-ucMGP and CAC scores. MGP SNP analysis revealed that patients homozygous for the C allele of the rs1800801 variant had a higher CAC score (median 15 [range 0-1312]) compared to patients carrying a T allele (median 0 [range 0-966] AU). These results indicate that plasma levels of dp-ucMGP are an independent predictor of increased VC in CKD5 patients and correlate with both higher CAC scores and degree of medial calcification. Additionally, high vascular expression of MGP was associated with higher CAC scores and plasma dp-ucMGP levels. Taken together, our results support that MGP is involved in the pathogenesis of VC.

Phenotypic features of vascular calcification in chronic kidney disease

BACKGROUND

Patients with chronic kidney disease stage 5 (CKD5) are predisposed to vascular calcification (VC), but the combined effect of factors associated with VC was sparsely investigated. We applied the relaxed linear separability (RLS) feature selection model to identify features that concomitantly associate with VC in CKD5 patients.

METHODS

Epigastric arteries collected during surgery from living donor kidney transplant recipients were examined to score the histological extent of medial VC. Sixty-two phenotypic features in 152 patients were entered into RLS model to differentiate between no-minimal VC (n = 93; score 0-1) and moderate-extensive VC (n = 59; score 2-3). The subset of features associated with VC was selected on the basis of cross-validation procedure. The strength of association of the selected features with VC was expressed by the absolute value of 'RLS factor'.

RESULTS

Among 62 features, a subset of 17 features provided optimal prediction of VC with 89% of patients correctly classified into their groups. The 17 features included traditional risk factors (diabetes, age, cholesterol, BMI and male sex) and markers of bone metabolism, endothelial function, metabolites, serum antibodies and mitochondrial-derived peptide. Positive RLS factors range from 1.26 to 4.05 indicating features associated with increased risk of VC, and negative RLS factors range from -0.95 to -1.83 indicating features associated with reduced risk of VC.

CONCLUSION

The RLS model identified 17 features including novel biomarkers and traditional risk factors that together concomitantly associated with medial VC. These results may inform further investigations of factors promoting VC in CKD5 patients.

Major fractures after initiation of dialysis: Incidence, predictors and association with mortality

BACKGROUND

Major fractures (MF) are common in dialysis patients. We investigated incidence, predictors and clinical outcomes associated with first MF occurring after initiation of dialysis (MF_first).

METHODS

In Swedish Renal Registry of 9714 incident (2005-2016) dialysis patients (age 68 years, 67% men), we identified all MF_first in hip, spine, humerus and forearm. Using flexible parametric hazard models and Fine-Gray analysis, we estimated incidence, mortality rates and predictors of MF_first, and, in time-dependent analysis, risk of all-cause and cardiovascular disease (CVD) mortality following MF_first.

RESULTS

During median follow-up of 2.2 years, the crude incidence rate of MFfirst (n = 835) was 23.7/1000 patient-years and that of hip fractures (n = 470) 13.3/1000 patient-years. The multivariate-adjusted fracture incidence rates increased gradually after dialysis initiation and were 47% higher among women. Female sex, higher age, comorbidity, and previous history of MF (MF_previous) were associated with increased risk for MF_first, whereas peritoneal dialysis as compared to hemodialysis was associated with decreased risk. The adjusted fracture incidence rate of MF_first during the first 90 days following dialysis initiation was higher in patients with MF_previous than in those without MF_previous. MF_first independently predicted increased all-cause (sub-distribution hazard ratio, SHR, 1.67(95%CI 1.47-1.91)) and CVD (SHR 1.49 (95%CI 1.22-1.84)) mortality. Adjusted mortality rate following hip fractures was higher than for other types of MF. Spline curves showed that mortality following MF_first was highest during the first 6 months of follow-up.

CONCLUSIONS

MF are common and associated with increased mortality in incident dialysis patients.

Antibodies against Malondialdehyde in Haemodialysis Patients and Its Association with Clinical Outcomes: Differences between Subclasses and Isotypes

Patients on haemodialysis (HD-patients) have an increased risk of premature death. Low levels of IgM antibodies against malondialdehyde (anti-MDA) are associated with increased risk of cardiovascular disease (CVD) with underlying potential mechanisms described. Here, we studied subclasses and isotypes of anti-MDA in 210 HD-patients with mortality as outcome (56% men, median age 66, Interquartile range (IQR) 51-74 years, vintage time 29 (15-58) months, mean follow up period of 41 (20-60)months). Patients were also divided into inflamed c-reactive protein (CRP >5.6 mg/mL) and non-inflamed. Antibody levels were measured by ELISA. In multivariate risk analysis, patients in low tertile of IgM anti-MDA sub-distribution hazard ratio (sHR 0.54); 95% confidence interval (CI: 0.34-0.89) inversely and significantly associated with all-cause mortality after five years, after adjusting for confounders. Low tertile of IgG (sHR 0.48, 95%CI: 0.25-0.90, p = 0.02) and IgG1 (sHR 0.50, CI: 0.24-1.04, p = 0.06) was associated low mortality among non-inflamed patients. In contrast, anti-MDA IgG2 among inflamed patients was significantly associated with increased mortality, IgG2(sHR 2.33, CI: 1.16-4.68, p = 0.01). IgM anti-MDA was a novel biomarker among HD-patients with low levels being associated with mortality, while low levels of IgG and IgG1 but not IgA anti-MDA were associated with mortality only among non-inflamed patients. IgG2 anti-MDA was a significant risk marker among inflamed patients, which could be related to infection.

Effects of Probiotic Supplementation on Trimethylamine-N-Oxide Plasma Levels in Hemodialysis Patients: a Pilot Study

Components present in the diet, L-carnitine, choline, and betaine are metabolized by gut microbiota to produce metabolites such as trimethylamine-N-oxide (TMAO) that appear to promote cardiovascular disease in chronic kidney disease (CKD) patients. The objective of this pilot study was to evaluate the effects of probiotic supplementation for 3 months on plasma TMAO levels in CKD patients on hemodialysis (HD). A randomized, double-blind trial was performed in 21 patients [54.8 ± 10.4 years, nine men, BMI 26.1 ± 4.8 kg/m², dialysis vintage 68.5 (34.2-120.7) months]. Ten patients were randomly allocated to the placebo group and 11 to the probiotic group [three capsules, totaling 9 × 10¹³ colony-forming units per day of Streptococcus thermophilus (KB19), Lactobacillus acidophilus (KB27), and Bifidobacteria longum (KB31). Plasma TMAO, choline, and betaine levels were measured by LC-MS/MS at baseline and after 3 months. While TMAO did not change after probiotic supplementation, there was a significant increase in betaine plasma levels. In contrast, the placebo group showed a significant decrease in plasma choline levels. Short-term probiotic supplementation does not appear to influence plasma TMAO levels in HD patients. Long-term studies are needed to determine whether probiotics may affect TMAO production in CKD patients.

Aortic Valve Calcium Associates with All-Cause Mortality Independent of Coronary Artery Calcium and Inflammation in Patients with End-Stage Renal Disease

BACKGROUND

Aortic valve calcium (AVC) and coronary artery calcium (CAC) are common complications in end-stage renal disease (ESRD). We investigated the prognostic significance of overlapping presence of AVC and CAC, and whether AVC was associated with all-cause mortality independent of the presence of CAC in ESRD.

METHODS

259 ESRD patients (median age 55 years, 67% males) undergoing cardiac computed tomography were included. Framingham risk score (FRS), presence of cardiovascular disease (CVD), statin use, nutritional status and other relevant laboratory data were determined at baseline. During follow-up for median 36 months, 44 patients died, and 68 patients underwent renal transplantation.

RESULTS

The baseline overlap presence of AVC and CAC was 37%. Multivariate regression analysis showed that FRS (odds ratio (OR) 2.25; 95% confidence interval (95% CI), 1.43-3.55) and CAC score (OR (95% CI), 2.18 (1.34-3.59)) were independent determinants of AVC. In competing-risk regression models adjusted for presence of CAC, inflammation, nutritional status, CVD, FRS and statin use, AVC remained independently associated with all-cause mortality (sub-hazard ratio (95% CI), 2.57 (1.20-5.51)).

CONCLUSIONS

The overlap of AVC and CAC was 37% in this ESRD cohort. AVC was associated with increased all-cause mortality independent of presence of CAC, traditional risk factors and inflammation.

Copeptin is independently associated with vascular calcification in chronic kidney disease stage 5

BACKGROUND

Vascular calcification (VC) is an independent predictor of cardiovascular disease (CVD) present in 30-70% of patients with chronic kidney disease (CKD). Copeptin is a sensitive surrogate marker of arginine vasopressin (AVP), which is involved in many pathophysiologic processes in CKD. The aim of the present study was to explore the association of copeptin with VC in CKD stage 5.

METHODS

Copeptin was investigated in conjunction with living donor kidney transplantation in 149 clinically stable CKD stage 5 patients (CKD5), including 53 non-dialyzed (CKD5-ND) and 96 dialysis patients treated by peritoneal dialysis (PD) (n = 43) or hemodialysis (HD) (n = 53). We analyzed the association of copeptin with presence and extent of VC ascertained both histologically in biopsies from the inferior epigastric artery (n = 137) and by coronary artery calcification (CAC) score measured by computed tomography.

RESULTS

Patients with higher copeptin were older, had higher systolic blood pressure, higher prevalence of CVD and their preceding time on chronic dialysis was longer. In Spearman's rank correlations (Rho), copeptin concentrations were significantly associated with CAC score (Rho = 0.27; p = 0.003) and presence of medial VC (Rho = 0.21; p = 0.016). Multivariate logistic regression analysis showed that 1-SD higher age, male gender, diabetes and 1-SD higher copeptin were significantly associated with the presence of moderate-extensive VC.

CONCLUSIONS

High circulating levels of copeptin in CKD5 patients are independently associated with the degree of medial calcification ascertained by histology of arterial biopsies. Thus, plasma copeptin may serve as a marker of the uremic calcification process.

Bone mineral density at different sites and 5 years mortality in end-stage renal disease patients: A cohort study

BACKGROUND

Bone disease with osteoporosis and renal osteodystrophy is common in end stage renal disease (ESRD) patients and associates with cardiovascular disease (CVD) and increased morbimortality. We investigated associations of low bone mineral density (BMD) at various bone sites with five year all-cause and CVD mortality in ESRD patients.

METHODS

In a post hoc analysis of 426 ESRD patients (median age 56 years, 62% men) starting dialysis, BMD (whole-body dual-energy X-ray absorptiometry, DXA), body composition, nutritional status (subjective global assessment, SGA), handgrip strength (%HGS), Framingham CVD risk score (FRS) and biochemical biomarkers of nutrition and inflammation were assessed. We used the Fine and Gray competing risk regression analysis to assess survival analysis.

RESULTS

In multivariate logistic regression analysis, %HGS and intact parathyroid hormone associated with low tertile of: BMD_total, BMD_head and BMD_pelvis, after adjusting for FRS, SGA, %HGS, s-albumin, hsCRP, lean body mass index and year of recruitment. Patients with high FRS had low BMD_head (p<0.001). Low tertile of BMD_total (sHR, 1.53), BMD_head (sHR 1.54) and BMD_pelvis (sHR 1.60) associated with increased all-cause mortality whereas no such associations were found for the trabecular bone rich sites BMD arm, leg, trunk, rib or spine. Low tertile of BMD_total (sHR 1.94), BMD_head (sHR 1.68), BMD_leg (sHR 2.25) and BMD_pelvis (sHR 2.45) associated with increased CVD mortality whereas BMD at other sites did not associate with CVD mortality.

CONCLUSION

Low head and pelvis BMD, and low total BMD, as assessed by whole-body DXA, were independent predictors of increased risk of all-cause and CVD mortality. Cortical BMD appeared to have stronger association to survival in ESRD than trabecular BMD.

Skin autofluorescence, arterial stiffness and Framingham risk score as predictors of clinical outcome in chronic kidney disease patients: a cohort study

BACKGROUND

The risk of cardiovascular disease (CVD) is predicted by Framingham's CVD risk scores (FRS) but the high CVD-related mortality in patients with chronic kidney disease (CKD) is only partially explained by traditional CVD risk markers. Therefore, there is a need to explore whether other CVD risk markers may improve risk prediction. Although arterial stiffness measured by augmentation index (AIx) and tissue content of advanced glycation end-products (AGEs) measured by skin autofluorescence (SAF) are two biomarkers that associate with CVD and mortality in CKD, it is not known how they compare with FRS. We evaluated associations between SAF, AIx and FRS, and their associations with CVD and mortality in CKD patients.

METHODS

SAF (AGE Reader) and AIx (SphygmoCor; adjusted for 75 heart beats per minute) were measured in 261 clinically stable and extensively phenotyped patients with CKD Stage 5 (median age 56 years, 66% male, 20% diabetes; 130 non-dialysed, 93 patients on peritoneal dialysis and 38 patients on haemodialysis). Multivariate receiver operator characteristics (ROC) curve analysis and multivariate Cox models followed by C-statistics were used to evaluate CVD-related and all-cause mortality risk associated with SAF, AIx and FRS during follow-up for median 25 months with 46 deaths.

RESULTS

In multivariate regression analysis, SAF associated with FRS, haemoglobin, fat body mass index and CVD, and inversely with per cent handgrip strength (HGS). AIx associated with FRS, and inversely with per cent HGS. Associations of SAF and AIx with high-sensitivity C-reactive protein (hsCRP), serum albumin, statin therapy and renal replacement therapy were not statistically significant. In ROC analysis, area under the curve (AUC) for CVD mortality ranged from AUC = 0.72 (AIx and FRS, respectively) to AUC = 0.78 (FRS + AIx), and for all-cause mortality from AUC = 0.70 (AIx) to AUC = 0.79 (FRS + AIx). In multivariate Cox analysis, after adjusting for 1-standard deviation (1-SD) of FRS, 1-SD increase of SAF associated with all-cause mortality and 1-SD increase of AIx associated with CVD mortality and all-cause mortality. After further adjustments for hsCRP, albumin and presence of CVD, AIx (but not SAF) remained independently associated with CVD mortality, hazard ratio (HR) 2.14 [95% confidence interval (95% CI) 1.18-3.89] and all-cause mortality, HR 1.74 (95% CI 1.16-2.60).

CONCLUSIONS

In patients with CKD Stage 5, SAF and aortic stiffness associated with mortality, independently of FRS. After adjusting for additional confounders including inflammation, aortic stiffness remained as an independent predictor of outcome. Since the contribution of SAF and aortic stiffness compared with FRS in ROC curve analysis was relatively modest, this underlines the importance of traditional CVD risk factors in CKD.

Comparative Analysis Between Computed Tomography and Surrogate Methods to Detect Low Muscle Mass Among Colorectal Cancer Patients

BACKGROUND

We aimed to evaluate the agreement between computed tomography (CT) and surrogate methods applied in clinical practice for the assessment of low muscle mass. In addition, we assessed the association between different muscle-assessment methods and nutrition status, as well as the prognostic value of low muscle mass on survival in patients with colorectal cancer (CRC).

METHODS

This is a cohort including 188 CRC patients with 17 months' follow-up (interquartile range: 12-23 months) for mortality. Low muscle mass was evaluated by corrected mid-upper arm muscle area (AMAc) and calf circumference, skeletal muscle mass by bioelectrical impedance analysis (BIA), muscle deficit by physical examination with the Patient-Generated Subjective Global Assessment (PG-SGA), and lumbar muscle cross-sectional area by CT (reference method).

RESULTS

The prevalence of low muscle mass ranged from 9.6% to 54.3% according to the method used. The physical examination had the highest κ coefficient compared with CT. Low muscularity was associated with the presence of malnutrition, lower body fat, and low phase angle. The Cox regression models-adjusted for age, sex, and treatment 3 months before study inclusion-showed that severe muscle loss measured by BIA and CT and low muscle mass measured by PG-SGA predicted higher mortality rates.

CONCLUSIONS

Compared with CT, the physical examination had the best agreement to assess low muscle mass. Low muscle mass assessed by PG-SGA, BIA, and CT showed similar prognostic values for survival.

Inter-leg systolic blood pressure difference predicts cardiovascular events and mortality in incident hemodialysis patients

BACKGROUND

High inter-arm blood pressure difference, a marker of vascular disease, may be difficult to assess in hemodialysis patients with arm arteriovenous fistulae. We investigated if high inter-leg systolic blood pressure difference associates with cardiovascular events and increased mortality in hemodialysis patients.

METHODS

Among 118 incident Japanese dialysis patients, bilateral leg blood pressure, arm blood pressure, brachial-ankle pulse wave velocity, and ankle-brachial index were measured, and the relative risk associated with inter-leg systolic blood pressure difference and other indices of vascular status was analyzed.

RESULTS

During follow-up (median, 46 months), 18 deaths and 75 cardiovascular events occurred in 38 patients. Kaplan-Meier curves showed that higher inter-leg systolic blood pressure difference was associated with overall (log-rank 9.35, p = 0.002) and cardiovascular (log-rank 5.81, p = 0.02) mortality. The period from the start of dialysis therapy to the first cardiovascular event was shorter as inter-leg systolic blood pressure difference increased (log-rank 23.7, p < 0.0001). In Cox hazard models, inter-leg systolic blood pressure difference greater than median independently predicted deaths (relative risk, 3.8; 95% confidence interval, 1.3-13.9) and cardiovascular events (relative risk, 3.9; 95% confidence interval, 1.9-9.21) after adjustments for age, sex, nutritional status, and diabetes, whereas other indices were not related to the risks. For well-nourished, moderately malnourished, and severely malnourished patients, the cumulative number of cardiovascular events in the high-inter-leg systolic blood pressure difference patients were 4.96, 31.44, and 55.18 events per 100 patient-years.

CONCLUSIONS

Higher inter-leg systolic blood pressure difference associated with increased risk of mortality and cardiovascular events suggesting that wider application of inter-leg systolic blood pressure difference measurements may be warranted in hemodialysis patients.

Chemerin inhibits vascular calcification through ChemR23 and is associated with lower coronary calcium in chronic kidney disease

BACKGROUND

Chemerin is an adipokine that signals through the G protein-coupled receptor ChemR23 and is associated with inflammation, glucose homeostasis, lipid metabolism and renal function, all of which strongly influence cardiovascular risk. However, elevated chemerin provides a survival advantage in patients with chronic kidney disease (CKD), but how this relates to the cardiovascular phenotype is unknown.

OBJECTIVES

The aim of the present study was to establish the association of chemerin with coronary calcification and to determine the effects of chemerin signalling, through ChemR23, in vascular smooth muscle cell (VSMC) calcification.

METHODS

Plasma chemerin was measured in 113 patients with CKD and 50 healthy controls. All patients underwent computed tomography to determine coronary artery calcium (CAC) score. VSMCs were isolated from wild-type and ChemR23 knock-out mice and treated with chemerin.

RESULTS

Multivariate analyses established creatinine, cholesterol, body mass index and tumour necrosis factor as significant confounders for circulating chemerin levels. Despite these positive associations with renal function, cardiometabolic risk factors and inflammation, chemerin was inversely associated with CAC both in an age- and sex-adjusted analysis and in a multivariate analysis adjusting for the aforementioned confounders. In addition, circulating chemerin levels were associated with the calcification inhibitors matrix gla protein (MGP) and fetuin-A. Finally, chemerin significantly reduced phosphate-induced calcification and increased MGP expression in VSMCs, whereas chemerin was devoid of these effects in VSMCs lacking ChemR23.

CONCLUSION

In conclusion, these results suggest that chemerin signalling through ChemR23 in VSMCs protects against vascular calcification in CKD.

Serum 8-hydroxydeoxyguanosine, a marker of oxidative DNA damage, is associated with mortality independent of inflammation in chronic kidney disease

BACKGROUND

Oxidative stress and low-grade systemic inflammation are common interrelated sequelae of chronic kidney disease (CKD) that associate with mortality. We investigated the association of serum 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, with mortality in CKD individuals and analyzed whether inflammation modifies the association.

METHODS

In 376 individuals with a wide range of estimated glomerular filtration rate (eGFR); >60 ml/min (n = 53), 15-60 ml/min (n = 60) and <15 ml/min (n = 263), cut-off values of serum 8-OHdG, high-sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), and tumor necrosis factor (TNF) as predictors of mortality were determined by ROC curves. We analyzed associations of 8-OHdG with inflammation markers and the overlapping effect of hsCRP, IL-6 and TNF on the association between 8-OHdG and all-cause mortality by multivariate generalized linear models.

RESULTS

In separate individual exposure analyses, higher 8-OHdG, hsCRP, and IL-6 (but not TNF) were each independently associated with increased risk of death in multivariate models adjusted for age, sex, diabetes mellitus, cardiovascular disease, protein-energy wasting, cohort calendar year, blood sample storage time and eGFR. For 8-OHdG, the multivariate relative risk ratio, RR_8-OHdG (95% confidence interval) 1.17 (1.08-1.26), remained essentially unchanged when adjusting also for inflammation in three separate models including: hsCRP, RR_8-OHdG = 1.15 (1.06-1.25); IL-6, RR_8-OHdG = 1.15 (1.07-1.25); and TNF, RR_8-OHdG = 1.16 (1.07-1.26).

CONCLUSIONS

Serum 8-OHdG, a biomarker of oxidative DNA damage, is associated with increased all-cause mortality risk in individuals with a wide range of eGFR and this association is independent of inflammation.

Reduced skeletal muscle expression of mitochondrial-derived peptides humanin and MOTS-C and Nrf2 in chronic kidney disease

Advanced chronic kidney disease (CKD) is characterized by a premature aging phenotype of multifactorial origin. Mitochondrial dysfunction is prevalent in CKD and has been proposed as a major contributor to poor muscle function. Although the mitochondria-derived peptides (MDPs) humanin and mitochondrial open reading frame of 12S rRNA-c (MOTS-c) are involved in cell survival, suppression of apoptosis, and glucose control, the implications of MDP in CKD are unknown. We investigated humanin and MOTS-c protein expression in skeletal muscle and serum levels in CKD at stage 5 (glomerular filtration rate: <15 ml/min) patients and age-matched controls with normal renal function. Whereas circulating levels of humanin were increased in CKD, local muscle expression was reduced. In contrast, MOTS-c levels were reduced in both skeletal muscle and serum in CKD. Humanin in serum correlated positively to circulating TNF levels. Reduced MDP levels in skeletal muscle were associated with lower mitochondrial density and evidence of oxidative stress. These results indicate a differential regulation of MDPs in CKD and suggest an alternative site for humanin production than skeletal muscle in the uremic milieu. MDP levels were linked to systemic inflammation and evidence of oxidative stress in the muscle, two hallmark features of premature aging and uremia.

The cholinergic anti-inflammatory pathway in resistant hypertension treated with renal denervation

Background

Renal denervation (RDN) reduces sympathetic tone and may alter the sympathetic-parasympathetic balance. The autonomic nervous system is partly a regulator of innate immunity via the cholinergic anti-inflammatory pathway (CAP) which inhibits inflammation via the vagus nerve. Placental Growth Factor (PlGF) influences a neuro-immunological pathway in the spleen which may contribute to hypertension. The aim of this study was to investigate if modulation of renal sympathetic nerve activity affects CAP in terms of cytokine release as well as levels of PlGF.

Methods

Ten patients treated with RDN (Medtronic Inc), were analyzed for TNF, IL-1b and IL-10 and Lipopolysaccharide (LPS)-stimulated cytokine release before RDN, 1 day after and at 3- and 6-months follow-up. Four patients who underwent elective coronary angiography served as disease controls (DC).

Results

Baseline TNF was significantly lower 1 day after RDN (p = 0.03). LPS-stimulated (0, 10 and 100 ng/mL) TNF and IL-1b were significantly lower 1 day after RDN (TNF p = 0.0009, p = 0.0009 and p = 0.001, IL-1b; p = 0.0001, p = 0.002 and p = 0.005). IL-10 was significantly higher one day after RDN (p = ns, p = 0.02 and p = 0.01). These differences however declined during follow up. A more marked TNF reduction was achieved with a cholinergic analogue, GTS-21, in LPS-stimulated whole blood as compared with samples without GTS-21. Cytokine levels in controls did not differ before and 1 day after coronary angiography. PlGF was significantly higher in RDN patients and DC compared with healthy controls but did not change during follow-up.

Conclusion

RDN has an immediate effect on TNF in vivo and cytokine release ex vivo but seems to wane over time suggesting that current RDN techniques may not have long-lasting immunomodulatory effect. Repeated and extended stimulation of CAP in resistant hypertension by targeting neural circuits may be a potential therapeutic strategy for treatment of both hypertension and inflammation.

Electronic supplementary material

The online version of this article (10.1186/s10020-019-0097-y) contains supplementary material, which is available to authorized users.

Early Vascular Ageing and Cellular Senescence in Chronic Kidney Disease

Chronic kidney disease (CKD) is a clinical model of premature ageing characterized by progressive vascular disease, systemic inflammation, muscle wasting and frailty. The predominant early vascular ageing (EVA) process mediated by medial vascular calcification (VC) results in a marked discrepancy between chronological and biological vascular age in CKD. Though the exact underlying mechanisms of VC and EVA are not fully elucidated, accumulating evidence indicates that cellular senescence - and subsequent chronic inflammation through the senescence-associated secretary phenotype (SASP) - plays a fundamental role in its initiation and progression. In this review, we discuss the pathophysiological links between senescence and the EVA process in CKD, with focus on cellular senescence and media VC, and potential anti-ageing therapeutic strategies of senolytic drugs targeting cellular senescence and EVA in CKD.