Chronic systemic inflammation in dialysis patients: an update on causes and consequences

Propionic acid supplementation promotes the expansion of regulatory T cells in patients with end-stage renal disease but not in renal transplant patients

In a previous study, we showed an anti-inflammatory effect of propionic acid supplementation in dialysis patients. The present study intends to analyze the effect of propionic acid on the chronic inflammatory state and T-cell composition in kidney transplant patients compared to dialysis patients. A total of 10 dialysis patients and 16 kidney transplant patients under immunosuppressive standard triple immunosuppressive therapy received 2 × 500 mg propionic acid per day for 30 days. The cellular immune system was analyzed before and after the propionic acid supplementation and 30-90 days thereafter as a follow-up. We measured the main immune cell types and performed an in-depth characterization of T cells including regulatory T cells (Tregs), B cells, and dendritic cells. In addition, we assessed the functional activity and antigenic responsiveness by analysis of third-party antigen-specific T cells after their stimulation by recall (tetanus diphtheria vaccine) antigen. In dialysis patients, we observed an expansion of CD25highCD127- Tregs after propionic acid intake. In contrast, the same supplementation did not result in any expansion of Tregs in transplant patients under immunosuppressive therapy. We also did not observe any changes in the frequencies of the main immune cell subsets except for CD4+/CD8+ distribution with an increase of CD4+ T cells and decrease of CD8+ T cells in the transplant population. Our data suggest that dietary supplements containing propionate might have a beneficial effect decreasing systemic inflammation in dialysis patients through Treg expansion. However, this effect was not observed in transplant patients, which could be explained by counteracting effect of immunosuppressive drugs preventing Treg expansion.

The effects of curcumin-containing supplementations on inflammatory markers and lipid profiles in patients with chronic kidney diseases: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

An evaluation the effects of curcumin on inflammatory markers and lipid profiles among patients with chronic kidney diseases (CKD).

METHODS

The electronic databases such as PubMed, and Scopus were searched systematically up until 12 December 2021. To evaluate the quality of the included studies, the Cochrane risk-of-bias tool for randomized trials was utilized. Likewise, data pooling was performed using a random effects model, also called a variance components model. Also, the findings were calculated as weighted mean difference (WMD) with a 95% confidence interval (CI).

RESULTS

In the end, this meta-analysis comprised a total number of nine studies. Curcumin intake significantly reduced total cholesterol (TC) (WMD=-13.77 mg/dL; 95% CI, -26.77, -0.77; p=0.04) and tumor necrosis factor alpha (TNF-α) (WMD=-18.87 pg/mL; 95% CI, -28.36, -9.38; p<0.001) compared with controls. The results did not confirm the significant effect of curcumin intake on triglyceride (TG) (WMD=-6.37 mg/dL; 95% CI, -26.59, 13.85; p=0.54), low-density lipoproteins (LDL-C) (WMD=-5.65 mg/dL; 95% CI, -20.81, 9.50; p=0.46), high-density lipoprotein (HDL-C) (WMD=0.16 mg/dL; 95% CI, -2.55, 2.88; p=0.91), and C-reactive protein (CRP) (WMD=-0.13 mg/L; 95% CI, -3.25, 3.30; p=0.93).

CONCLUSIONS

Our study showed that curcumin significantly impacts TC and TNF levels in CKD patients.

The Signaling Pathway of TNF Receptors: Linking Animal Models of Renal Disease to Human CKD

Chronic kidney disease (CKD) has been recognized as a global public health problem. Despite the current advances in medicine, CKD-associated morbidity and mortality remain unacceptably high. Several studies have highlighted the contribution of inflammation and inflammatory mediators to the development and/or progression of CKD, such as tumor necrosis factor (TNF)-related biomarkers. The inflammation pathway driven by TNF-α, through TNF receptors 1 (TNFR1) and 2 (TNFR2), involves important mediators in the pathogenesis of CKD. Circulating levels of TNFRs were associated with changes in other biomarkers of kidney function and injury, and were described as predictors of disease progression, cardiovascular morbidity, and mortality in several cohorts of patients. Experimental studies describe the possible downstream signaling pathways induced upon TNFR activation and the resulting biological responses. This review will focus on the available data on TNFR1 and TNFR2, and illustrates their contributions to the pathophysiology of kidney diseases, their cellular and molecular roles, as well as their potential as CKD biomarkers. The emerging evidence shows that TNF receptors could act as biomarkers of renal damage and as mediators of the disease. Furthermore, it has been suggested that these biomarkers could significantly improve the discrimination of clinical CKD prognostic models.

Cause of postoperative mortality in patients with end-stage renal disease

Background: The number of patients with end-stage renal disease (ESRD) who are dependent on hemodialysis is increasing rapidly. As a result, more patients with ESRD need surgery. These patients have a significantly higher risk of postoperative death than those with normal kidney function. Therefore, this study analyzed the causes of postoperative mortality in ESRD patients undergoing surgery under general anesthesia and the risk factors for postoperative mortality.Methods: This retrospective analysis examined the mortality of ESRD patients, 20 to 80 years old, undergoing surgery under general anesthesia. We excluded patients who underwent cardiac, cancer, or emergency surgery or organ transplantation from the analysis. The primary outcome was the cause of postoperative 30-day mortality in ESRD patients. We also assessed the mortality rate and risk factors.Results: There were 2,459 eligible ESRD patients. When patients underwent multiple surgeries during the study period, only the last surgery was considered. In total, 167 patients died during the study period, including 65 within 30 days postoperatively. The cause of death was sepsis in 22 cases (33.8%) and a major cardiac event in 16 (24.6%). Atrial fibrillation, current angina, previous myocardial infarction, asthma, lower hemoglobin and albumin levels, and a larger intraoperative colloid volume were likely to increase mortality. Conclusions: Our study suggests that immunological issues have a significant role in the death of ESRD patients after general anesthesia.

A single-centre, retrospective analysis of mortality over 80 months comparing paclitaxel-coated balloon versus standard balloon angioplasty in the treatment of dysfunctional arteriovenous access

AIM

Percutaneous transluminal angioplasty (PTA) is a standard treatment for arteriovenous fistula (AVF) stenosis to preserve haemodialysis vascular access, promoting improved dialysis adequacy and better outcomes for those dependent on renal replacement therapy. Drug coated balloons (DCB) may help reduce the rate of neointimal hyperplasia and recurrent stenosis, but their use in femoropopliteal angioplasty has been associated with increased mortality at 2 and 5 year follow-up. This study aims to address the long-term safety of PTA for AVF stenosis with clinical correlation to participant co-morbidity and mortality.

METHODS

All patients undergoing PTA for AVF stenosis at a single centre between 2013 and 2017 were identified and grouped according to the use of DCB versus standard balloon angioplasty. All data was anonymised and correlated to verify independent predictors of mortality.

RESULTS

481 (400 standard balloon; 81 DCB) procedures were performed in 313 patients (250 standard balloon; 63 DCB). Follow-up at 80 months did not show any difference in mortality (p = 0.546). Multivariate analysis identified time on dialysis (p < 0.001), age (p = 0.001) and Charlson comorbidity index (p = 0.02) as independent predictors of mortality.

CONCLUSIONS

In this study, mortality was not associated with the use of DCBs, but was related to established factors of dialysis longevity, age and comorbidity.

Renal and non-renal response of ABC and SLC transporters in chronic kidney disease

INTRODUCTION

The solute carrier (SLC) and the ATP-binding cassette (ABC) transporter superfamilies play essential roles in the disposition of small molecules (endogenous metabolites, uremic toxins, drugs) in the blood, kidney, liver, intestine, and other organs. In chronic kidney disease (CKD), the loss of renal function is associated with altered function of remote organs. As renal function declines, many molecules accumulate in the plasma. Many studies now support the view that ABC and SLC transporters as well as drug metabolizing enzymes (DMEs) in renal and non-renal tissues are directly or indirectly affected by the presence of various types of uremic toxins, including those derived from the gut microbiome; this can lead to aberrant inter-organ communication.

AREAS COVERED

Here, the expression, localization and/or function of various SLC and ABC transporters as well as DMEs in the kidney and other organs are discussed in the context of CKD and systemic pathophysiology.

EXPERT OPINION

According to the Remote Sensing and Signaling Theory (RSST), a transporter and DME-centric network that optimizes local and systemic metabolism maintains homeostasis in the steady state and resets homeostasis following perturbations due to renal dysfunction. The implications of this view for pharmacotherapy of CKD are also discussed.

The Use of Curcumin for the Treatment of Renal Disorders: A Systematic Review of Randomized Controlled Trials

Chronic kidney disease (CKD) is one of the significant causes of morbidity and mortality worldwide, which could develop and progress to end-stage renal disease. Increased inflammation and reduced antioxidant capacity commonly occur in CKD and hemodialysis patients. Curcumin is a natural bioactive compound with antioxidant and anti-inflammatory properties. This systematic review was undertaken with the main aim of assessing the effects of curcumin/turmeric supplementation on renal diseases based on clinical trials. A comprehensive search was performed in PubMed/MEDLINE, Scopus, ISI Web of Science, and Google Scholar from inception up to April 6, 2020 to identify clinical trials assessing the effects of curcumin or turmeric alone, or in combination with other herbs or nutrients on renal diseases. Twelve studies met the eligibility criteria. These randomized controlled trials (RCTs) comprised 631 patients with either chronic kidney diseases (CKD), hemodialysis, diabetic proteinuria and nephropathy, and lupus nephritis. Curcumin/turmeric supplementation had favorable effects on renal diseases, particularly in terms of inflammation and oxidative stress. However, with the exception for proteinuria, their impact on clinical parameters, such as blood urea nitrogen, creatinine, glomerular filtration rate (GFR), and serum albumin, was weak and not significant. No serious adverse effects were reported following curcumin/turmeric supplementation. Within the limitations of this review, it can be concluded that curcumin/turmeric supplementation might have some beneficial effects on inflammatory and oxidative stress parameters of patients but no considerable positive impact on clinical outcomes of kidney diseases, apart from proteinuria.

End-Stage Renal Disease Patients on Chronic Hemodialysis Fare Better With COVID-19: A Retrospective Cohort Study From the New York Metropolitan Region

Introduction

Several comorbid conditions have been identified as risk factors in patients with coronavirus disease 2019 (COVID-19). However, there is a dearth of data describing the impact of COVID-19 infection in patients with end-stage renal disease on hemodialysis (ESRD-HD).

Methods

This retrospective case series analyzed 362 adult patients consecutively hospitalized with confirmed COVID-19 illness between March 12, 2020, and May 13, 2020, at a teaching hospital in the New York City metropolitan area. The primary outcome was severe pneumonia as defined by the World Health Organization. Secondary outcomes were the (1) the Combined Outcome of Acute respiratory distress syndrome or in-hospital Death (COAD), and (2) need for high levels of oxygen supplementation (HiO₂).

Results

Patients with ESRD-HD had lower odds for poor outcomes including severe pneumonia [odds ratio (OR) 0.4, confidence interval (CI) 0.2-0.9, p=.04], HiO₂ [OR 0.3, CI (0.1-0.8), p=.02] and COAD [OR 0.4, CI (0.2-1.05), p=.06], when compared to patients without ESRD. In contrast, higher odds for severe pneumonia, COAD and HiO₂ were seen with advancing age. African Americans were over-represented in the hospitalized patient cohort, when compared to their representation in the community (35% vs 18%). Hispanics had higher odds for severe illness and HiO₂ when compared to Caucasians.

Conclusions

Patients with ESRD-HD had a milder course of illness with a lower likelihood of severe pneumonia and a lesser need for aggressive oxygen supplementation when compared to patients not on chronic dialysis. The lower odds of severe illness in ESRD-HD patients might have a pathophysiologic basis and need to be further explored.

Immune Dysfunction in Uremia 2020

Cardiovascular disease and infections are major causes for the high incidence of morbidity and mortality of patients with chronic kidney disease. Both complications are directly or indirectly associated with disturbed functions or altered apoptotic rates of polymorphonuclear leukocytes, monocytes, lymphocytes, and dendritic cells. Normal responses of immune cells can be reduced, leading to infectious diseases or pre-activated/primed, giving rise to inflammation and subsequently to cardiovascular disease. This review summarizes the impact of kidney dysfunction on the immune system. Renal failure results in disturbed renal metabolic activities with reduced renin, erythropoietin, and vitamin D production, which adversely affects the immune system. Decreased kidney function also leads to reduced glomerular filtration and the retention of uremic toxins. A large number of uremic toxins with detrimental effects on immune cells have been identified. Besides small water-soluble and protein-bound compounds originating from the intestinal microbiome, several molecules in the middle molecular range, e.g., immunoglobulin light chains, retinol-binding protein, the neuropeptides Met-enkephalin and neuropeptide Y, endothelin-1, and the adipokines leptin and resistin, adversely affect immune cells. Posttranslational modifications such as carbamoylation, advanced glycation products, and oxidative modifications contribute to uremic toxicity. Furthermore, high-density lipoprotein from uremic patients has an altered protein profile and thereby loses its anti-inflammatory properties.

The Role of Fibroblast Growth Factor 23 in Inflammation and Anemia

In patients with chronic kidney disease (CKD), adverse outcomes such as systemic inflammation and anemia are contributing pathologies which increase the risks for cardiovascular mortality. Amongst these complications, abnormalities in mineral metabolism and the metabolic milieu are associated with chronic inflammation and iron dysregulation, and fibroblast growth factor 23 (FGF23) is a risk factor in this context. FGF23 is a bone-derived hormone that is essential for regulating vitamin D and phosphate homeostasis. In the early stages of CKD, serum FGF23 levels rise 1000-fold above normal values in an attempt to maintain normal phosphate levels. Despite this compensatory action, clinical CKD studies have demonstrated powerful and dose-dependent associations between FGF23 levels and higher risks for mortality. A prospective pathomechanism coupling elevated serum FGF23 levels with CKD-associated anemia and cardiovascular injury is its strong association with chronic inflammation. In this review, we will examine the current experimental and clinical evidence regarding the role of FGF23 in renal physiology as well as in the pathophysiology of CKD with an emphasis on chronic inflammation and anemia.

Intrinsic tumor necrosis factor-α pathway is activated in a subset of patients with focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is frequently found in biopsies of patients with steroid resistant nephrotic syndrome (SRNS). The pathogenesis of SRNS/FSGS is often unknown and the disease will recur in up to 50% of patients post-transplant, indicating the presence of circulating podocyte-toxic factor(s). Several studies have reported clinical improvement after anti-TNFα therapy. However, prediction of the clinical outcome in SRNS/FSGS is difficult, and novel predictive biomarkers are needed. An image-based assay, which measures disassembly of focal adhesion complexes in cultured podocytes, was used to ascertain the presence of podocyte toxic activity in SRNS/FSGS sera. Expression of TNFα pathway genes was analysed in the Nephroseq FSGS cohort and in cultured podocytes treated with SRNS/FSGS sera. Podocyte toxic activity was detected in 48/96 SRNS/FSGS patients. It did not correlate with serum TNFα levels, age, sex, ethnicity or glomerular filtration rate. In ~25% of the toxic samples, the toxicity was strongly inhibited by blockade of TNFα signaling. Transcriptional profiling of human FSGS biopsies and podocytes treated with FSGS sera revealed significant increases in expression of TNFα pathway genes. We identified patients with serum podocyte toxic activity who may be at risk for FSGS recurrence, and those patients in whom serum podocyte toxicity may be reversed by TNFα blockade. Activation of TNFα pathway genes occurs in podocytes of FSGS patients suggesting a causative effect of this pathway in response to circulating factor(s). In vitro analyses of patient sera may stratify patients according to prognostic outcomes and potential responses to specific clinical interventions.

Association Between Serum Prealbumin Level and Outcomes in Prevalent Kidney Transplant Recipients

OBJECTIVE(S)

Prealbumin, a transport protein mostly synthesized in the liver, is a marker of nutrition. Although decreased prealbumin levels are associated with increased mortality in end-stage kidney disease patients, its association with mortality in kidney transplant recipients remains unknown. We evaluated the association between prealbumin levels and outcomes in kidney transplant recipients.

DESIGN

This was a prospective prevalent cohort study. This study included 991 kidney transplant recipients enrolled from December 31, 2006, to December 31, 2007, and followed over a 6-year period. Sociodemographic, past medical history, clinical, and laboratory data were collected at the study entry. Associations between prealbumin levels and death with functioning graft, all-cause mortality, and graft loss were examined using survival models.

RESULTS

Serum prealbumin levels showed significant negative correlation with estimated glomerular filtration rate (R = -0.28; P < .001) and high-sensitive C-reactive protein (R = -0.24; P < .001). Each 5 mg/dL lower serum prealbumin level was associated with 20% higher risk of death with functioning graft (subdistribution hazard ratio [95% confidence interval]: 1.20 [1.08-1.35]; P = .001), which persisted after multivariable adjustments (subdistribution hazard ratio [95% confidence interval]: 1.13 [1.00-1.28]; P = .039). Qualitatively similar trend was observed in all-cause mortality; however, there was no association between prealbumin levels and graft loss.

CONCLUSION(S)

Lower serum prealbumin level is associated with increased risk of death with functioning graft in prevalent kidney transplant recipients.

A focused review on optimal coronary revascularisation in patients with chronic kidney disease: Coronary revascularisation in kidney disease

Concomitant chronic kidney disease (CKD) and coronary artery disease (CAD) is known to have poor outcomes. With a thorough literature review, we discuss the pathophysiological basis behind accelerated atherosclerosis in CKD, and the role of percutaneous coronary intervention (PCI) in these patients, focusing on drug-eluting stents, coronary artery bypass grafting, and adverse outcomes. We discuss factors contributing to poor outcomes in these patients, and the need for more work in this subgroup.

High-Density Lipoprotein from Chronic Kidney Disease Patients Modulates Polymorphonuclear Leukocytes

The anti-inflammatory properties of high-density lipoproteins (HDL) are lost in uremia. These HDL may show pro-inflammatory features partially as a result of changed protein composition. Alterations of polymorphonuclear leukocytes (PMNLs) in chronic kidney disease (CKD) may contribute to chronic inflammation and high vascular risk. We investigated if HDL from uremic patients is related to systemic inflammation by interfering with PMNL function. PMNL apoptosis was investigated by assessing morphological features and DNA content. CD11b surface expression was quantified by flow cytometry. Oxidative burst was measured via cytochrome c reduction assay. Chemotaxis was assessed by using an under-agarose migration assay. We found that HDL from CKD and hemodialysis (HD) patients significantly attenuated PMNL apoptosis, whereas HDL isolated from healthy subjects had no effect on PMNL apoptosis. The use of signal transduction inhibitors indicated that uremic HDL exerts anti-apoptotic effects by activating pathways involving phosphoinositide 3-kinase and extracellular-signal regulated kinase. Healthy HDL attenuated the surface expression of CD11b, whereas HDL from CKD and HD patients had no effect. All tested isolates increased the stimulation of oxidative burst, but did not affect PMNL chemotactic movement. In conclusion, HDL may contribute to the systemic inflammation in uremic patients by modulating PMNL functions.

Impact of arteriovenous fistula blood flow on serum il-6, cardiovascular events and death: An ambispective cohort analysis of 64 Chinese hemodialysis patients

Flows (Qa) of arteriovenous fistula (AVF) impact the dialysis adequacy in hemodialysis (HD) patients. However, data for different access flow levels on outcomes related to long-term dialysis patients, especially in Chinese patients, are limited. Herein, we performed an ambispective, mono-centric cohort study investigating the association between the AVF flows and inflammation, cardiovascular events and deaths in Chinese hemodialysis patients bearing a radio-cephalic fistula (AVF) from 2009 to 2015. Twenty-three patients (35.9%) developed at least one episode of cardiovascular disease (CVD) in two years after AVF creation. AVF Qa, IL-6 and hsCRP were significantly higher in patients with CVD than in patients without CVD. Multi-factorial binary logistic regression analysis found that the independent and strongest risk factor for CVD in HD patients was serum IL-6, which showed a positive association with AVF Qa levels in patients. Therefore, the linkage between AVF Qa tertiles and adverse clinical outcomes (cardiovascular events and mortality) was examined over a median follow-up of five years. IL-6 was significantly increased in the high AVF Qa (>1027.13 ml/min) group. Patients with median AVF Qa showed the lowest morbidity and mortality of CVD according to the AVF Qa tertiles, whereas higher Qa was associated with a higher risk of CVD, and lower AVF Qa (600 ml/min ≤AVF Qa <821.12 ml/min) had a higher risk of non-CVD death. Therefore, keeping the AVF Qa at an optimal level (821.12 to 1027.13 ml/min) would benefit HD patients, improve long-term clinical outcomes and lower AVF-induced inflammation.

Plasma protein-bound di-tyrosines as biomarkers of oxidative stress in end stage renal disease patients on maintenance haemodialysis

Background

Patients with end-stage renal disease (ESRD) undergoing haemodialysis (HD) experience enhanced oxidative stress and systemic inflammation, which are risk factors for cardiovascular disease, the most common cause of excess morbidity and mortality for these patients. Different pathways producing different types of oxidative stress occur in ESRD. The purpose of our study was to determine the effect of HD on plasma levels of protein-bound dityrosine (di-Tyr), a biomarker of protein oxidation.

Methods

Protein-bound di-Tyr formation was measured by size exclusion HPLC coupled to fluorescence detector. Clinical laboratory parameters were measured by standardized methods.

Results

In most ESRD patients, a single HD session decreased significantly the plasma protein-bound di-Tyr level, although the mean post-HD level remained significantly greater than the one in healthy people. Furthermore, pre-HD plasma protein-bound di-Tyr level was positively correlated with pre-HD serum creatinine and albumin concentrations. No significant correlation was found between plasma protein-bound di-Tyr level and serum concentration of C-reactive protein, a biomarker of systemic inflammation.

Conclusions

This study demonstrates that a single HD session does not increase, rather partially decreases, oxidative pathways producing di-Tyr in the haemodialyzed patient.

General significance

The choice of the most pertinent biomarkers of oxidative stress is critical for the development of novel treatments for ESRD. However, the relative importance of oxidative stress and inflammation in ESRD remains largely undetermined, and several questions concerning oxidative stress and inflammation remain poorly defined. These results could stimulate further studies on the use of plasma protein-bound di-Tyr as a long-lasting oxidative stress biomarker in ESRD.

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Haemodialyzed patients experience oxidative stress and systemic inflammation.

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We assessed haemodialysis (HD) effect on plasma protein-bound dityrosine (di-Tyr).

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In most patients, a single HD session decreased significantly the di-Tyr level.

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Pre-HD di-Tyr level was positively correlated with those of creatinine and albumin.

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No correlation was found between di-Tyr level and C-reactive protein concentration.

Oxidative stress and cardiac dysfunction in children with chronic renal failure on regular hemodialysis

OBJECTIVE

The objective of this study was to evaluate cardiac function in children with end-stage renal disease (ESRD) on regular hemodialysis using speckle tracking echocardiography (STE) and correlate results with plasma glutathione level as a marker of oxidative stress.

METHODS

The study involved 30 children with ESRD and 30 healthy controls. The plasma glutathione and C-reactive protein (CRP) levels were measured, and cardiac function was evaluated using conventional echocardiography and STE.

RESULTS

Plasma glutathione levels were significantly lower and CRP significantly higher in patients than in controls. Children with ESRD had significant systolic and diastolic cardiac dysfunctions detected by STE compared with controls. Conventional echocardiography failed to detect these dysfunctions. There was significant increase in left-ventricular relative wall thickness (LV-RWT) in patients, especially those with hypertension, compared with the control group. There was also significant impairment of LV and right-ventricular (RV) global longitudinal strain (GLS) and torsion; however, LV-GLS was significantly better in hypertensive than in normotensive patients. The degree of impairment in GLS and cardiac torsion negatively correlated with plasma glutathione levels.

CONCLUSION

Significant oxidative stress was present in children with ESRD and was correlated with the degree of cardiac dysfunction detected early using the new cardiac imaging modality, STE.

Effect of different stages of chronic kidney disease and renal replacement therapies on oxidant-antioxidant balance in uremic patients

Oxidative stress seems to be involved in the path physiology of cardiovascular complications of chronic kidney disease (CKD). In this study, we determined the effect of different stages of CKD and substitutive therapies on oxidative stress. One hundred sixty-seven patients (age: 44 ± 06 years; male/female: 76/91) with CKD were divided into 6 groups according to the National Kidney Foundation classification. Prooxidant status was assessed by assaying thiobarbituric acid reactive substances, hydroperoxides, and protein carbonyls. Antioxidant defence was performed by analysis of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, vitamin E, Iron, and bilirubin. TBARS and LPO were higher in HD patients compared to other groups (P < 0.001), while protein carbonyls were more increased in PD patients. The antioxidant enzymes were declined already at severe stage of CKD and they were declined notably in HD patients (P < 0.001). Similar observation was found for vitamin E, Fe, and bilirubin where we observed a significant decrease in the majority of study groups, especially in HD patients (P < 0.001). The evolution of CKD was associated with elevated OS. HD accentuates lipid, while PD aggravates protein oxidation. However, the activity of antioxidant enzymes was altered by impaired renal function and by both dialysis treatments.

Targeted complement inhibition as a promising strategy for preventing inflammatory complications in hemodialysis

Hemodialysis is the most common method used to remove waste and hazardous products of metabolism in patients suffering from renal failure. Hundreds of thousands of people with end-stage renal disease undergo hemodialysis treatment in the United States each year. Strikingly, the 5-year survival rate for all dialysis patients is only 35%. Most of the patients succumb to cardiovascular disease that is exacerbated by the chronic induction of inflammation caused by contact of the blood with the dialysis membrane. The complement system, a strong mediator of pro-inflammatory networks, is a key contributor to such biomaterial-induced inflammation. Though only evaluated in experimental ex vivo settings, specific targeting of complement activation during hemodialysis has uncovered valuable information that points toward the therapeutic use of complement inhibitors as a means to control the unwelcomed inflammatory responses and consequent pathologies in hemodialysis patients.

The uraemic toxin phenylacetic acid contributes to inflammation by priming polymorphonuclear leucocytes

BACKGROUND

The activation of polymorphonuclear leucocytes (PMNLs) causes inflammation and as a result cardiovascular disease, which is a main risk factor for increased morbidity and mortality in patients with chronic kidney disease. Toxins accumulating in uraemic patients play a major role in modulating essential PMNL functions and apoptosis, the latter being crucial for a coordinated resolution of inflammation. One uraemic toxin is phenylacetic acid (PAA). We therefore investigated whether PAA contributes to the deranged immune response in uraemia by modulating PMNL activities.

METHODS

PMNL oxidative burst, phagocytosis and surface expression of the activation markers CD11b and CD18 were measured by flow cytometry in whole blood from healthy subjects in the presence and absence of PAA. Spontaneous apoptosis of isolated PMNLs was assessed by evaluating morphological features under the fluorescence microscope and by measuring the DNA content by flow cytometry. PMNL chemotaxis was tested by the under-agarose method.

RESULTS

PAA significantly enhanced the stimulation of PMNL oxidative burst by Escherichia coli, phagocytosis of E. coli by PMNLs and the expression of CD11b and CD18 at the PMNL surface. PAA significantly decreased PMNL apoptosis resulting in an increased percentage of viable cells. PAA affected neither the oxidative burst stimulated by phorbol-12-myristate-13-acetate nor PMNL chemotaxis.

CONCLUSIONS

PAA increases the activation of various PMNL functions and the expression of surface activation markers, while it attenuates PMNL apoptotic cell death. Therefore, PAA may contribute to the inflammatory state and consequently to increased cardiovascular risk in uraemic patients.

Relationships between appetite and quality of life in hemodialysis patients

The aim of this paper was to investigate the association between appetite and kidney-disease specific quality of life in maintenance hemodialysis patients. Quality of life (QoL) was measured using the kidney disease quality of life survey. Appetite was measured using self-reported categories and a visual analog scale. Other nutritional parameters included Patient-Generated Subjective Global Assessment (PGSGA), dietary intake, body mass index and biochemical markers C-reactive protein and albumin. Even in this well nourished sample (n=62) of hemodialysis patients, PGSGA score (r=-0.629), subjective hunger sensations (r=0.420) and body mass index (r=-0.409) were all significantly associated with the physical health domain of QoL. As self-reported appetite declined, QoL was significantly lower in nine domains which were mostly in the SF36 component and covered social functioning and physical domains. Appetite and other nutritional parameters were not as strongly associated with the Mental Health domain and Kidney Disease Component Summary Domains. Nutritional parameters, especially PGSGA score and appetite, appear to be important components of the physical health domain of QoL. As even small reductions in nutritional status were associated with significantly lower QoL scores, monitoring appetite and nutritional status is an important component of care for hemodialysis patients.

Complement anaphylatoxin C5a contributes to hemodialysis-associated thrombosis

Thrombosis is a common complication of end-stage renal disease, particularly in patients on hemodialysis. Although substantial progress has been made in preventing thrombotic complications in various other groups of patients, the mechanisms of thrombosis during hemodialysis require clarification. In this report, we demonstrate that complement activation triggered by hemodialysis biomaterials, and the subsequent generation of the complement anaphylatoxin C5a, results in the expression of functionally active tissue factor (TF) in peripheral blood neutrophils. Because TF is a key initiator of coagulation in vivo, we postulate that the recurring complement activation that occurs during long-term hemodialysis contributes to thrombosis in dialyzed end-stage renal disease patients. Furthermore, we found that complement contributed to the induction of granulocyte colony-stimulating factor, which has been implicated in the pathogenesis of thrombosis in patients treated with the recombinant form of this molecule. Importantly, the inhibition of complement activation attenuated the TF expression and granulocyte colony-stimulating factor induction in blood passing through a hemodialysis circuit, suggesting that the complement system could become a new therapeutic target for preventing thrombosis in patients with chronic renal failure who are maintained on hemodialysis.

Endothelial dysfunction in peritoneal dialysis patients with and without failed renal transplants

BACKGROUND

Endothelial dysfunction (ED) is a common, early abnormality that predisposes patients to develop atherosclerosis and cardiovascular events; inflammation is associated with atherosclerosis and malnutrition. Patients with failed transplants are usually complicated by inflammation; however, ED in this group of patients has not been well defined. In this cross-sectional study, we sought to investigate ED among naïve peritoneal dialysis (nPD) patients who were never transplanted as well as patients with failed renal transplants who were re-starting peritoneal dialysis (fTxPD).

METHODS

Twenty-five nPD patients (15 female/10 males; mean age, 44 +/- 11 years), and 12 fTxPD patients (4 males; mean age, 37 +/- 10 years) were included in the study. Coronary flow reserve (CFR) measurements were used to evaluate ED. Serum creatinine, calcium, phosphorus, total cholesterol, albumin, hemoglobin, and intact parathyroid hormone (iPTH) were measured. Also, highly sensitive C-reactive protein (hs-CRP) levels and weekly Kt/V were determined as possible confounding factors. Results were compared between the 2 groups.

RESULTS

There were no significant differences regarding age, gender, mean systolic and diastolic blood pressures, or smoking status. Mean duration on PD, peritoneal transport characteristics, PD modality and doses, frequency of peritonitis episodes, as well as serum creatinine, calcium, phosphorus, total cholesterol, albumin, hemoglobin and iPTH levels were similar between the 2 groups. Weekly Kt/V of both groups were similar as well. However, hs-CRP levels were significantly higher (34 +/- 52 vs 6.7 +/- 7.5 mg/L; P = .017) and CFR significantly lower among patients with fTxPD compared with nPD patients (1.52 +/- 0.20 vs 1.91 +/- 0.53; P = .022).

CONCLUSION

ED was more prominent among patients with failed transplants than nPD cases, suggesting that the failed allograft may be responsible for this abnormality.

Human uraemic plasma stimulates release of leptin and uptake of tumour necrosis factor-alpha in visceral adipocytes

BACKGROUND

End-stage renal disease (ESRD) is commonly associated with anorexia, malnutrition and inflammation. In addition to serving as the primary reservoir for energy storage, adipocytes produce numerous pro- and anti-inflammatory mediators and regulate food intake by releasing the appetite-suppressing (leptin) and appetite-stimulating (adiponectin) hormones. Under normal conditions, release of leptin is stimulated by feeding to prevent excess intake, and release of adiponectin is stimulated by fasting to induce feeding. However, under certain pathological conditions such as inflammation, maladaptive release of these hormones leads to anorexia, wasting and malnutrition and simultaneously intensifies inflammation. Anorexia, malnutrition and inflammation in ESRD are frequently accompanied by hyper-leptinaemia. This study was designed to test the hypothesis that uraemic plasma may stimulate leptin release and suppress adiponectin release in normal adipocytes.

METHODS

Visceral adipose tissue was harvested from normal rats, and adipocytes were isolated and incubated for 2-4 h in media containing 90% plasma from 12 ESRD patients (before and after haemodialysis) and 12 normal control subjects.

RESULTS

The ESRD group had a marked elevation of plasma TNF-alpha, IL-6, IL-8 and leptin concentrations before and after haemodialysis. Incubation in media containing plasma from the ESRD group elicited a much greater leptin release by adipocytes than that containing normal plasma. Post-dialysis plasma evoked an equally intense leptin release. The rise in leptin release was coupled with a parallel fall in TNF-alpha concentration in the incubation media. In contrast to leptin, adiponectin release in the presence of uraemic plasma was similar to that found with the control plasma.

CONCLUSIONS

Exposure to uraemic plasma induces exuberant release of leptin that is coupled with avid uptake of TNF-alpha by visceral adipocytes. These observations confirm the role of TNF-alpha, formerly known as cachexin, in the over-production and release of leptin in patients with ESRD.

Postprandial intradialytic dysglycaemia and diabetes in maintenance haemodialysis patients

BACKGROUND

Although the risk of developing dysglycaemia has been investigated in different communities this incidence is poorly studied in patients on maintenance haemodialysis (MHD).

MATERIALS AND METHODS

In a multicentre observational cohort study the occurrence of dysglycaemia was assessed in 239 primary normoglycaemic end stage renal disease (ERSD) patients on MHD. Dysglycaemia (fasting blood glucose > 110 mg dL(-1), > 140 mg dL(-1) 2 h after food intake) or diabetes (fasting blood glucose > 126 mg dL(-1) or > 200 mg dL(-1) at any time) were defined according to WHO criteria and cases were compared with age matched controls within the cohort.

RESULTS

Dysglycaemia was found in 82 primary normoglycaemic ESRD patients (34%) within 31 months after initiation of MHD. In 31 of these patients type 2 diabetes was diagnosed. When compared with matched control MHD patients differences in body mass index (BMI), HbA1c and postprandial blood glucose were detectable (P < 0.05). Increments in 0.1% of HbA1c were related with 11% higher odds for dysglycaemia (P = 0.002). In a subgroup of 36 primary normoglycaemic MHD patients who developed dysglycaemia event-free survival was 64%, 53%, 31%, 17% and 11% after 1, 2, 3, 4 and 5 years of haemodialysis treatment.

CONCLUSION

Onset of dysglycaemia or diabetes is frequent in ESRD patients after onset of chronic haemodialysis. Routine measurement of blood glucose before and after haemodialysis should be implemented as a standard of care during MHD.

The uraemic retention solute para-hydroxy-hippuric acid attenuates apoptosis of polymorphonuclear leukocytes from healthy subjects but not from haemodialysis patients

BACKGROUND

Disturbed polymorphonuclear leukocyte (PMNL) apoptosis contributes to the dysregulation of the non-specific immune system in uraemia. Intracellular Ca(2+) modulates PMNL apoptotic cell death. We investigated the effect of para-hydroxy-hippuric acid (PHA), an erythrocyte plasma membrane Ca(2+)-ATPase inhibitor accumulating in uraemic sera, and of cyclopiazonic acid (CPA), an inhibitor of the sarko/endoplasmatic Ca(2+)-ATPase, on PMNL apoptosis.

METHODS

Apoptosis of PMNLs from healthy subjects and from haemodialysis (HD) patients was assessed after incubation for 20 h by evaluating morphological features under the fluorescence microscope and by measuring the DNA content and caspase activities by flow cytometry. The intracellular calcium concentration ([Ca(2+)](i)) was determined by measurement of fura-2 fluorescence using the 340/ 380 nm dual wavelength excitation.

RESULTS

Spontaneous apoptosis of PMNLs from healthy subjects and from HD patients did not differ. PHA significantly attenuated, while CPA increased, the apoptotic cell death of PMNLs from healthy subjects. The PHA effect was not observed with PMNLs from HD patients, irrespective of whether the blood was drawn before or after HD treatment. Baseline [Ca(2+)](i) was increased in PMNLs obtained from HD patients before dialysis but reversed after dialysis. The PHA effects were not mediated via [Ca(2+)](i). The chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP) induced a [Ca(2+)](i) increase and reduced PMNL survival. Extracellular Ca(2+) did not affect CPA- and fMLP-induced apoptosis.

CONCLUSIONS

PHA, without affecting [Ca(2+)](i), attenuates apoptosis of healthy but not of uraemic PMNLs. CPA and fMLP enhance PMNL apoptosis independently of Ca(2+) influx.

Development of multiple complications in type 2 diabetes is associated with the increase of multiple markers of chronic inflammation

Patients with type 2 diabetes (T2DM) are known at risk for developing cardiovascular disease (CVD), nephropathy, and cancer. We were interested to find out whether multiple markers associated with chronic inflammation are detectable in patients with T2DM and are increased in patients with T2DM who developed additional clinical complications. A sequence of multiple risk markers for atherogenesis, associated with chronic inflammation, was measured in patients with T2DM before and after the development of clinical complications. We found that multiple clinical complications frequently developed simultaneously in patients with T2DM. At the early stage of T2DM, only low levels and low percent elevations of multiple risk markers were detected. However, both the level and the percent elevation of these markers were found to increase with disease progression and the development of clinical complications. We believe that chronic inflammation not only contributes to the pathogenesis of T2DM but also continues to increase in T2DM patients who are developing additional clinical complications. It appears that these multiple markers are potentially useful not only for monitoring the progression of T2DM but also predicting the risk of developing macro- and microvascular disease, nephropathy, and cancer.

Low triiodothyronine and cardiomyopathy in patients with end-stage renal disease

OBJECTIVES AND METHODS

Low free plasma triiodothyronine (fT3) is associated with inflammation and cardiovascular damage in patients with end-stage renal disease (ESRD). We investigated the relationship between fT3, left ventricular systolic function and left ventricular mass in a group of 234 dialysis patients, and modelled the association between fT3 and cardiomyopathy in statistical analyses including both direct (interleukin-6 and C-reactive protein) and inverse (serum albumin) acute phase inflammation markers.

RESULTS

Plasma fT3 concentration in dialysis patients was significantly (P < 0.001) reduced in comparison with healthy participants and clinically euthyroid patients with normal renal function. Left ventricular systolic function was depressed (P <or= 0.003) and left ventricular mass increased (P < 0.001) in patients in the first fT3 quartile as compared with patients in other quartiles. In multiple regression analyses these associations remained significant also after adjustment for Framingham risk factors and antihypertensive therapy (P </= 0.01), and for risk factors peculiar to ESRD (P = 0.03). Adjustments for interleukin-6 or for albumin, however, abrogated these relationships.

CONCLUSIONS

Low triiodothyronine is associated with left ventricular dysfunction and left ventricular hypertrophy in ESRD patients. These associations appear largely mediated by inflammation. Low fT3 may be an intermediate mechanism implicated in the adverse cardiac effects of inflammation in patients with ESRD.

Ultrapure dialysate and inflammatory response in haemodialysis evaluated by darbepoetin requirements—a randomized study

BACKGROUND

Dialysate quality has been suggested to influence inflammation status in patients subject to haemodialysis (HD). The aim of this study was to compare ultrapure dialysate (UPD) vs conventional dialysate (CD) with respect to darbepoetin requirements and other inflammation markers.

METHODS

A controlled prospective randomized study was carried out on 78 patients from two HD units who were treated with low-flux polyamide dialysers. Patients were assigned to two groups by using different sized blocks per unit and dialysis session. One group received CD treatment while the other was treated with UPD over 12 months. From the groups, 37 patients started treatment with CD and 41 with UPD while 31 patients ended with CD and 30 with UPD. The main variables analysed were haemoglobin (Hb) and darbepoetin dose; other variables studied were C-reactive protein (CRP), albumin, interleukin-6 (IL-6) and interleukin-1 receptor antagonist (IL-1Ra).

RESULTS

No significant differences were observed between the two groups for the variables analysed. At the beginning of the study the following values of CD and UPD were assessed: Hb 11.3 and 11.3 (g/dl); darbepoetin dose: 0.49 and 0.44 (microg/kg/week); CRP: 13 and 24 (mg/l); albumin: 3.8 and 3.7 (g/dl); IL-6: 5.94 and 4.18; and IL-1Ra: 345 and 420 (ng/l), respectively. At the end of the study the values of CD and UPD were: Hb 12 and 11.9 (g/dl); darbepoetin dose: 0.47 and 0.48 (microg/kg/week); CRP: 14 and 14 (mg/l); albumin: 3.8 and 3.7 (g/dl); IL-6: 14.03 and 12.93 and IL-1Ra: 322 and 340 (ng/l).

CONCLUSIONS

UPD does not improve the inflammatory status evaluated by darbepoetin requirements in conventional HD patients treated with low-flux polyamide dialyser. Further controlled studies are required to evaluate the clinical influence of UPD in HD with other low- and high-flux membranes.

Recent advances in understanding the malnutrition-inflammation-cachexia syndrome in chronic kidney disease patients: What is next?

Several recent clinical trials using single modalities to correct the conventional cardiovascular risk factors in patients with chronic kidney disease (CKD) or to improve dialysis dose and techniques in maintenance dialysis patients have failed despite the high rate of cardiovascular mortality in these individuals. Protein-energy malnutrition and inflammation, two relatively common and concurrent conditions in CKD patients, have been implicated as the main cause of poor short-term survival in this population. The "malnutrition-inflammation-cachexia syndrome" (MICS) appears to be the main cause of worsening atherosclerotic cardiovascular disease in the CKD population. The MICS is associated with low serum cholesterol and homocysteine levels and leads to "cachexia in slow motion." Hence a reverse epidemiology of cardiovascular risk factors is observed in dialysis patients with a paradoxical association of obesity, hypercholesterolemia, and hyperhomocysteinemia with better survival. Correction of MICS can potentially ameliorate the cardiovascular epidemic in CKD patients. Because MICS is multifactorial, its correction will require an integral approach rather than a single intervention. The ongoing obsession with conventional cardiovascular risk factors largely reflecting overnutrition in a population that suffers from the short-term consequences of undernutrition and excessive inflammation may well be fruitless. Clinical trials focusing on the causes and consequences of MICS and its modulation using nutritional interventions may be the key to improving survival in these individuals.

Contrast nephropathy may be partly mediated by autonomic dysfunction: renal failure considered as a modern maladaptation of the prehistoric trauma response

The mechanism behind iodinated radiocontrast nephropathy remains elusive. Direct oxidative damage is the prevailing hypothesis, but the apparent protective effect of iodine against oxidation contradicts this view. We propose that autonomic dysfunction participates in the pathogenesis of radiocontrast nephropathy and may account for other contrast-associated reactions previously attributed to allergy. Iodine, through its effects on thyroid function and chemoreceptor response to metabolic acidosis, may induce hyperadrenergia and consequently diminish renovascular flow and urine output. The renal response to adrenergia likely served an adaptive function during prehistoric evolution when trauma was a dominant source of hypovolemia and adrenergia, but the response may behave maladaptively today as evolutionarily nai ve triggers for adrenergia have emerged. Autonomic dysfunction can further impair renal function by deranging renovascular autoregulation and inducing oxidative reperfusion injury as a secondary phenomenon. Many other causes of acute renal failure such as drug toxicity, surgery, hospitalization, and diabetes may operate through hyperadrenergia, impaired renovascular autoregulation, and oxidative reperfusion injury. Dialysis, a volume reduction therapy for renal failure, can counterintuitively worsen renal dysfunction by exacerbating adrenergia, which may explain its association with accelerated atherosclerosis, inflammation, and cancer. Other examples of vicious cycles that perpetuate renal dysfunction may include renal artery stenosis, carotid stenosis, and atherosclerosis as well as the cardio-renal, hepato-renal, and pulmonary-renal syndromes. The benefits of hydration and bicarbonate in protecting renal function may operate in part through baroreceptor- and chemoreceptor-mediated reduction of sympathovagal ratio, respectively. New treatment paradigms for renal failure including pharmacologic and electro-mechanical therapies are envisioned based on autonomic remodeling, reduced sympathovagal ratio, and neuromodulation of pathways typically associated with trauma such as renin, angiotensin, vasopressin, and aldosterone.

Kidney insufficiency and nutrient-based modulation of inflammation

PURPOSE OF REVIEW

Patients with chronic kidney disease have a high cardiovascular mortality rate. Despite recent advances in dialysis techniques, over 20% of US dialysis patients die every year. Protein-energy malnutrition and inflammation are common and usually concurrent in chronic kidney disease patients, and have been implicated as the main cause of high mortality. We reviewed the pathophysiology of the malnutrition-inflammation complex syndrome and its potential modulation by dietary and other nutritional interventions in chronic kidney disease patients.

RECENT FINDINGS

The malnutrition-inflammation complex syndrome is a main cause of the atherosclerotic cardiovascular disease epidemic in chronic kidney disease. This may be by virtue of the syndrome's inflammatory components. Malnutrition and inflammation lead to weight loss over time, i.e. cachexia in slow motion, and result in decreased serum cholesterol and homocysteine levels. A 'reverse epidemiology' of cardiovascular risk factors is observed in chronic kidney disease, in that obesity, hypercholesterolemia and hyperhomocysteinemia are paradoxically associated with better survival. Among the possible etiologies of the malnutrition-inflammation complex syndrome, anorexia, low nutrient intake and oxidative stress are theoretically amenable to dietary modulation; however, the bulk of findings are epidemiological.

SUMMARY

There is no consensus as to how to correct the malnutrition-inflammation complex syndrome in chronic kidney disease patients. Because the malnutrition-inflammation complex syndrome is multifactorial, its correction probably requires a battery of simultaneous interventions, rather than one single modality. Clinical trials focusing on the syndrome are currently non-existent and are therefore urgently required to improve poor clinical outcome in chronic kidney disease patients.

Immune dysfunction in uremia

Kidney dysfunction leads to disturbed renal metabolic activities and to impaired glomerular filtration, resulting in the retention of toxic solutes affecting all organs of the body. Cardiovascular disease (CVD) and infections are the main causes for the increased occurrence of morbidity and mortality among patients with chronic kidney disease (CKD). Both complications are directly or indirectly linked to a compromised immune defense. The specific coordinated roles of polymorphonuclear leukocytes (PMNLs), monocytes/macrophages, lymphocytes and antigen-presenting cells (APCs) in maintaining an efficient immune response are affected. Their normal response can be impaired, giving rise to infectious diseases or pre-activated/primed, leading to inflammation and consequently to CVD. Whereas the coordinated removal via apoptosis of activated immune cells is crucial for the resolution of inflammation, inappropriately high apoptotic rates lead to a diminished immune response. In uremia, the balance between pro- and anti-inflammatory and between pro- and anti-apoptotic factors is disturbed. This review summarizes the interrelated parameters interfering with the immune response in uremia, with a special focus on the non-specific immune response and the role of uremic toxins.