ABSTRACT
Emerging evidence suggests that intestinal dysbiosis plays an important role in host inflammation locally and systemically. Such pathological condition is even more prevailing in patients ...with chronic kidney disease (CKD). Of note, indoxyl sulphate (IS), a gut‐derived uremic toxin, is notorious for its pro‐inflammatory feature in CKD patients. IS accumulates in the body as the urinary excretion of uremic toxins is impaired, and further worsens the kidney function in a vicious cycle to CKD. Dietary restriction in vegetables, fruits and yogurt leads to the predominance of indole‐producing intestinal microbial flora and further exaggerates the accumulation of IS in CKD patients. Recently, interventional studies have shown that circulating IS can be reduced by dietary prebiotic and/or probiotic supplements. However, further randomized controlled trials are warranted to examine whether such beneficial effect of dietary prebiotic/probiotic supplements could be extrapolated to better hard outcomes in CKD population. In this review, we would also like to emphasize the importance of achieving sufficient intake of dietary fibre by proper vegetable pre‐treatment and accurate fruit selection, instead of directly avoiding these potassium‐rich yet fibre‐rich and base‐producing foods.
Summary at a Glance
The accumulation of indoxyl sulphate, a gut‐derived uremic toxin which is notorious for its pro‐inflammatory feature, in CKD patients is exaggerated by the dietary restriction on vegetables, fruits, and yogurt, which leads to the predominance of indole‐producing intestinal microbial flora. Thus in order to establish gut symbiosis in CKD patients, it's important to achieve sufficient intake of dietary fiber by proper vegetable pretreatment and accurate fruit selection, instead of directly avoiding these potassium‐rich yet fiber‐rich and base‐producing foods.
An inverse relationship between body mass index (BMI) and mortality (the obesity paradox) has been found in patients with non-dialysis-dependent chronic kidney disease (CKD). However, it is unclear ...whether increased muscle mass or body fat confers the survival advantage. To resolve this we investigated the impact of body makeup on a composite outcome of death or cardiovascular events in a prospective cohort of 326 patients with stage 3–5 CKD not yet on dialysis. Lean mass and body fat were determined using the Body Composition Monitor, a multifrequency bioimpedance spectroscopy device, and were expressed as the lean tissue or fat tissue index, respectively. Patients were stratified as High (above median) or Low (below median) BMI, High or Low lean tissue index, or as High or Low fat tissue index. During a median follow-up of 4.6 years, there were 40 deaths and 68 cardiovascular events. In Cox proportional hazards models, a High lean tissue index, but not High BMI or High fat tissue index, predicted a lower risk of both the composite or its component outcomes (reference: below median). When patients were further stratified into four distinct body composition groups based on both the lean and fat tissue index, only the High lean/fat tissue index group had a significantly lower risk of the composite outcome (hazard ratio 0.36, 95% confidence interval 0.14–0.87; reference: Low lean/fat tissue index group). Thus, the lean tissue index can provide better risk prediction than the BMI alone in non-dialysis-dependent patients with CKD. The High lean/fat tissue index appears to be associated with best outcomes. An optimal body composition for improving the prognosis of CKD needs to be determined.
Background
Volume overload is frequently encountered and is associated with cardiovascular risk factors in patients with chronic kidney disease (CKD). However, the relationship between volume ...overload and adverse outcomes in CKD is not fully understood.
Methods and Results
A prospective cohort of 338 patients with stage 3 to 5 CKD was followed for a median of 2.1 years. The study participants were stratified by the presence or absence of volume overload, defined as an overhydration index assessed by bioimpedance spectroscopy exceeding 7%, the 90th percentile for the healthy population. The primary outcome was the composite of estimated glomerular filtration rate decline ≥50% or end‐stage renal disease. The secondary outcome included a composite of morbidity and mortality from cardiovascular causes. Animal models were used to simulate fluid retention observed in human CKD. We found that patients with volume overload were at a higher risk of the primary and secondary end points in the adjusted Cox models. Furthermore, overhydration appears to be more important than hypertension in predicting an elevated risk. In rats subjected to unilateral nephrectomy and a high‐salt diet, the extracellular water significantly increased. This fluid retention was associated with an increase in blood pressure, proteinuria, renal inflammation with macrophage infiltration and tumor necrosis factor‐α overexpression, glomerular sclerosis, and cardiac fibrosis. Diuretic treatment with indapamide attenuated these changes, suggesting that fluid retention might play a role in the development of adverse outcomes.
Conclusions
Volume overload contributes to CKD progression and cardiovascular diseases. Further research is warranted to clarify whether the correction of volume overload would improve outcomes for CKD patients.
Bilirubin is a well-known neurotoxin in newborn infants; however, current evidence has shown that a higher serum bilirubin concentration in physiological ranges is associated with a lower risk for ...the development and progression of both chronic kidney disease (CKD) and cardiovascular disease (CVD) in adults. The protective mechanisms of bilirubin in CVD, CKD, and associated mortality may be ascribed to its antioxidant and anti-inflammatory properties. Bilirubin further improves insulin sensitivity, reduces low-density lipoprotein cholesterol levels and inhibits platelet activation in at-risk individuals. These effects are expected to maintain normal vascular homeostasis and thus reduce the incidence of CKD and the risks of cardiovascular complications and death. In this review, we highlight the recent advances in the biological actions of bilirubin in the pathogenesis of CVD and CKD progression, and further propose that targeting bilirubin metabolism could be a potential approach to ameliorate morbidity and mortality in CKD patients.
Chronic kidney disease (CKD) is known to increase the risk of atrial fibrillation (AF) development, but the relationship between AF and subsequent renal function decline in patients with CKD is not ...well understood. In this study, we explored the role of AF on renal outcomes among patients with CKD.
In a retrospective hospital-based cohort study, we identified patients with CKD aged ≥20 years from 1 January 2008 to 31 December 2018. The patients were divided into AF and non-AF groups. We matched each patient with CKD and AF to two non-AF CKD controls according to propensity scores. The outcomes of interest included estimated glomerular filtration rate (eGFR) decline of ≥20%, ≥30%, ≥40% and ≥50%, and end-stage renal disease (ESRD).
After propensity score matching, 6731 patients with AF and 13 462 matched controls were included in the analyses. Compared with the non-AF group, the AF group exhibited greater risks of eGFR decline ≥20% (HR 1.43; 95% CI 1.33 to 1.53), ≥30% (HR 1.50; 95% CI 1.36 to 1.66), ≥40% (HR 1.62; 95% CI 1.41 to 1.85) and ≥50% (HR 1.82; 95% CI 1.50 to 2.20), and ESRD (HR 1.22; 95% CI 1.12 to 1.34). Higher CHA
DS
-VASc scores were associated with greater risks of eGFR decline and ESRD.
In patients with CKD, AF was associated with greater risks of subsequent renal function decline. CHA
DS
-VASc scores may be a useful risk stratification scheme for predicting the risk of renal function decline.
Background
The link between elevated serum uric acid (SUA) levels and cardiovascular disease (CVD)–related mortality in the elderly population remains inconclusive. Nutritional status influences both ...SUA and CVD outcomes. Therefore, we investigated whether SUA‐predicted mortality and the effect‐modifying roles of malnourishment in older people.
Methods and Results
A longitudinal Taiwanese cohort including 127 771 adults 65 years and older participating in the Taipei City Elderly Health Examination Program from 2001 to 2010 were stratified by 1‐mg/dL increment of SUA. Low SUA (<4 mg/dL) strata was categorized by malnourishment status defined as Geriatric Nutritional Risk Index <98, serum albumin <38 g/L, or body mass index <22 kg/m2. Study outcomes were all‐cause and CVD‐related mortality. Cox models were used to estimate hazard ratios (HRs) of mortality, after adjusting for 20 demographic and comorbid covariates. Over a median follow‐up of 5.8 years, there were 16 439 all‐cause and 3877 CVD‐related deaths. Compared with the reference SUA strata of 4 to <5 mg/dL, all‐cause mortality was significantly higher at SUA <4 mg/dL (HR, 1.16; 95% confidence interval, 1.07–1.25) and ≥8 mg/dL (HR, 1.13; confidence interval, 1.06–1.21), with progressively elevated risks at both extremes. Similarly, increasingly higher CVD‐related mortality was found at the SUA level <4 mg/dL (HR, 1.19; confidence interval, 1.00–1.40) and ≥7 mg/dL (HR, 1.17; confidence interval, 1.04–1.32). Remarkably, among the low SUA (<4 mg/dL) strata, only malnourished participants had greater all‐cause and CVD‐related mortality. This modifying effect of malnourishment remained consistent across subgroups.
Conclusions
SUA ≥8 or <4 mg/dL independently predicts higher all‐cause and CVD‐related mortality in the elderly, particularly in those with malnourishment.
Anemia affects millions of patients with chronic kidney disease (CKD) and prompt iron supplementation can lead to reductions in the required dose of erythropoiesis-stimulating agents, thereby ...reducing medical costs. Oral and intravenous (IV) traditional iron preparations are considered far from ideal, primarily due to gastrointestinal intolerability and the potential risk of infusion reactions, respectively. Fortunately, the emergence of novel iron replacement therapies has engendered a paradigm shift in the treatment of iron deficiency anemia in patients with CKD. For example, oral ferric citrate is an efficacious and safe phosphate binder that increases iron stores to maintain hemoglobin levels. Additional benefits include reductions in fibroblast growth factor 23 levels and the activation of 1,25 dihydroxyvitamin D. The new-generation IV iron preparations ferumoxytol, iron isomaltoside 1000, and ferric carboxymaltose are characterized by a reduced risk of infusion reactions and are clinically well tolerated as a rapid high-dose infusion. In patients undergoing hemodialysis (HD), ferric pyrophosphate citrate (FPC) administered through dialysate enables the replacement of ongoing uremic and HD-related iron loss. FPC transports iron directly to transferrin, bypassing the reticuloendothelial system and avoiding iron sequestration. Moreover, this paper summarizes recent advancements of hypoxia-inducible factor prolyl hydroxylase inhibitors and future perspectives in renal anemia management.
High-dose intravenous iron supplementation is associated with adverse cardiovascular outcomes in patients with CKD, but the underlying mechanism is unknown. Our study investigated the causative role ...of iron sucrose in leukocyte-endothelium interactions, an index of early atherogenesis, and subsequent atherosclerosis in the mouse remnant kidney model. We found that expression levels of intracellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and adhesion of U937 cells increased in iron-treated human aortic endothelial cells through upregulated NADPH oxidase (NOx) and NF-κB signaling. We then measured mononuclear-endothelial adhesion and atherosclerotic lesions of the proximal aorta in male C57BL/6 mice with subtotal nephrectomy, male apolipoprotein E-deficient (ApoE(-/-)) mice with uninephrectomy, and sham-operated mice subjected to saline or parenteral iron loading. Iron sucrose significantly increased tissue superoxide production, expression of tissue cell adhesion molecules, and endothelial adhesiveness in mice with subtotal nephrectomy. Moreover, iron sucrose exacerbated atherosclerosis in the aorta of ApoE(-/-) mice with uninephrectomy. In patients with CKD, intravenous iron sucrose increased circulating mononuclear superoxide production, expression of soluble adhesion molecules, and mononuclear-endothelial adhesion compared with healthy subjects or untreated patients. In summary, iron sucrose aggravated endothelial dysfunction through NOx/NF-κB/CAM signaling, increased mononuclear-endothelial adhesion, and exacerbated atherosclerosis in mice with remnant kidneys. These results suggest a novel causative role for therapeutic iron in cardiovascular complications in patients with CKD.
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