Soluble CD14 levels, interleukin 6, and mortality among prevalent hemodialysis patients

sCD14 as a biomarker for the progression of kidney disease among patients with diabetes

AIMS

To investigate the association of soluble CD14 (sCD14) with diabetic kidney disease (DKD) and its prediction performance for kidney function staging.

METHODS

A cross-sectional study of 80 type 2 diabetes (T2D) patients was conducted. Each participant was screened for DKD, and the diagnostic criterion for DKD was a glomerular filtration rate (eGFR) <60 mL/min/1.73m2. Serum sCD14 was measured by ELISA technique. Logistic regression models and receiver operating characteristics (ROC) curves were used to assess the association of sCD14 with DKD and its predictive value for disease staging.

RESULTS

sCD14 was higher in DKD patients than in T2D patients without kidney disease (p < 0.001). sCD14 was progressively higher in DKD patients according to the kidney function stage (p < 0.001). Also, sCD14 was higher in DKD patients in hemodialysis than those who did not receive renal replacement therapy (p < 0.001). In DKD patients, sCD14 was positively correlated with creatinine (r = 0.282, p = 0.042) and negatively correlated with eGFR (r = -0.365, p = 0.007). The levels of sCD14 were predictive of G3 (AUC = 0.822), G4 (AUC = 0.876), and G5 (AUC = 0.924) stages of kidney function. In a multivariate logistic regression model adjusted for age, sex, and diabetes duration, sCD14 ≥ 1720 ng/mL were associated with G3 stage (OR = 8.92, p = 0.023), G4 (OR = 7.92, p = 0.011) and G5 stage (OR = 18.47, p = 0.017) in DKD patients.

CONCLUSION

Circulating levels of sCD14 are associated with DKD and perform well for kidney function staging. Thus, it is a good candidate for assessing the risk of kidney disease progression.

The mechanism of enterogenous toxin methylmalonic acid aggravating calcium-phosphorus metabolic disorder in uremic rats by regulating the Wnt/β-catenin pathway

BACKGROUND

Uremia (UR) is caused by increased UR-related toxins in the bloodstream. We explored the mechanism of enterogenous toxin methylmalonic acid (MMA) in calcium-phosphorus metabolic disorder in UR rats via the Wnt/β-catenin pathway.

METHODS

The UR rat model was established by 5/6 nephrectomy. The fecal bacteria of UR rats were transplanted into Sham rats. Sham rats were injected with exogenous MMA or Salinomycin (SAL). Pathological changes in renal/colon tissues were analyzed. MMA concentration, levels of renal function indicators, serum inflammatory factors, Ca2+/P3+, and parathyroid hormone, intestinal flora structure, fecal metabolic profile, intestinal permeability, and glomerular filtration rate (GFR) were assessed. Additionally, rat glomerular podocytes were cultured, with cell viability and apoptosis measured.

RESULTS

Intestinal flora richness and diversity in UR rats were decreased, along with unbalanced flora structure. Among the screened 133 secondary differential metabolites, the MMA concentration rose, showing the most significant difference. UR rat fecal transplantation caused elevated MMA concentration in the serum and renal tissues of Sham rats. The intestinal flora metabolite MMA or exogenous MMA promoted intestinal barrier impairment, increased intestinal permeability, induced glomerular podocyte loss, and reduced GFR, causing calcium-phosphorus metabolic disorder. The intestinal flora metabolite MMA or exogenous MMA induced inflammatory responses and facilitated glomerular podocyte apoptosis by activating the Wnt/β-catenin pathway, which could be counteracted by repressing the Wnt/β-catenin pathway.

CONCLUSIONS

Enterogenous toxin MMA impelled intestinal barrier impairment in UR rats, enhanced intestinal permeability, and activated the Wnt/β-catenin pathway to induce glomerular podocyte loss and reduce GFR, thus aggravating calcium-phosphorus metabolic disorder.

Virion-incorporated CD14 enables HIV-1 to bind LPS and initiate TLR4 signaling in immune cells

HIV-1 has a broad range of nuanced interactions with the immune system, and the incorporation of cellular proteins by nascent virions continues to redefine our understanding of the virus-host relationship. Proteins located at the sites of viral egress can be selectively incorporated into the HIV-1 envelope, imparting new functions and phenotypes onto virions, and impacting viral spread and disease. Using virion capture assays and western blot, we show that HIV-1 can incorporate the myeloid antigen CD14 into its viral envelope. Virion-incorporated CD14 remained biologically active and able to bind its natural ligand, bacterial lipopolysaccharide (LPS), as demonstrated by flow virometry and immunoprecipitation assays. Using a Toll-like receptor 4 (TLR4) reporter cell line, we also demonstrated that virions with bound LPS can trigger TLR4 signaling to activate transcription factors that regulate inflammatory gene expression. Complementary assays with THP-1 monocytes demonstrated enhanced secretion of inflammatory cytokines like tumor necrosis factor alpha (TNF-α) and the C-C chemokine ligand 5 (CCL5), when exposed to LPS-loaded virus. These data highlight a new type of interplay between HIV-1 and the myeloid cell compartment, a previously well-established cellular contributor to HIV-1 pathogenesis and inflammation. Persistent gut inflammation is a hallmark of chronic HIV-1 infection, and contributing to this effect is the translocation of microbes across the gut epithelium. Our data herein provide proof of principle that virion-incorporated CD14 could be a novel mechanism through which HIV-1 can drive chronic inflammation, facilitated by HIV-1 particles binding bacterial LPS and initiating inflammatory signaling in TLR4-expressing cells.IMPORTANCEHIV-1 establishes a lifelong infection accompanied by numerous immunological changes. Inflammation of the gut epithelia, exacerbated by the loss of mucosal T cells and cytokine dysregulation, persists during HIV-1 infection. Feeding back into this loop of inflammation is the translocation of intestinal microbes across the gut epithelia, resulting in the systemic dissemination of bacterial antigens, like lipopolysaccharide (LPS). Our group previously demonstrated that the LPS receptor, CD14, can be readily incorporated by HIV-1 particles, supporting previous clinical observations of viruses derived from patient plasma. We now show that CD14 can be incorporated by several primary HIV-1 isolates and that this virion-incorporated CD14 can remain functional, enabling HIV-1 to bind to LPS. This subsequently allowed CD14+ virions to transfer LPS to monocytic cells, eliciting pro-inflammatory signaling and cytokine secretion. We posit here that virion-incorporated CD14 is a potential contributor to the dysregulated immune responses present in the setting of HIV-1 infection.

Serum interleukin 18 level in kidney diseases and age

Background

Interleukin-18 (IL-18), also known as interferon-gamma inducing factor is a protein which in humans is encoded by the IL18 gene, it is a member of the IL 1 family and has a molecular weight of 18 kDa. Innate and adaptive immunity can be regulated by IL-18, and disorders involving its dysregulation might result in inflammatory or autoimmune conditions.

Aim of the Work

To distinguish between acute kidney injury (AKI) and chronic renal failure (CRF), this research investigates the utility of IL-18 as a novel biomarker and examines how age affects its level.

Materials and Methods

Three hundred participants were included and divided into three groups using the following methodology. Group I consisted of 100 control subjects who were split up by age and gender. Group II consisted of 100 AKI patients who were divided into two groups and subgroups based on age and gender. Group III, which consisted of 100 CRF (hemodialyzed patients), was divided into two groups and subgroups, as patients with acute renal injury and previously healthy people. Patients' blood was drawn to conduct a laboratory investigation blood urea, serum creatinine, sodium, potassium, pH, GFR and PCO2.

Results

Patients with CRF had higher serum levels of IL-18 than patients with AKI, regardless of gender, and both groups of patients had levels of IL-18 that rise with age.

Conclusion

IL-18 is a reliable indicator for the differentiation between AKI and CRF patients receiving hemodialysis and its level correlates with age independent with gender.

Admission serum creatinine in non-hemodialysis-dependent patients with spontaneous supratentorial intracerebral hemorrhage: Is it a prognosticator?

INTRODUCTION

Spontaneous intracerebral hemorrhage (ICH) carries a high mortality rate, with end-stage renal disease (ESRD) and hemodialysis being risk factors for early mortality. However, the role of admission serum creatinine in ICH prognosis remains unclear. This study aimed to analyze the correlation between admission serum creatinine levels and short-term ICH prognosis in non-hemodialysis-dependent patients.

METHODS

This retrospective study analyzed 296 adult patients admitted with spontaneous supratentorial ICH. Demographic, clinical, and radiographic data were collected, including admission serum creatinine levels. The primary outcomes were mortality and unfavorable outcomes, defined as Modified Rankin Scale scores of 4-6. Univariate or multivariate analysis was performed to examine the association between admission serum creatinine levels and ICH prognosis, with and without the inclusion of maintenance hemodialysis patients.

RESULTS

Among all patients, elevated admission serum creatinine levels were significantly associated with increased mortality (OR = 1.39, 95% CI: 1.21-1.59, P < 0.01). However, this association disappeared when excluding patients undergoing maintenance hemodialysis (OR = 0.95, 95% CI: 0.53-1.69, P = 0.86). No significant association was found between admission serum creatinine levels and unfavorable outcomes. Other well-established prognostic factors, such as age and admission GCS, demonstrated significant associations with both mortality and unfavorable outcomes in multivariate analysis.

CONCLUSION

Admission serum creatinine appears to have limited prognostic value in non-hemodialysis-dependent patients with spontaneous supratentorial ICH. Our findings suggest that the relationship between renal function and ICH prognosis is complex and may be influenced by factors such as comorbidities and maintenance hemodialysis.

Biomarkers and Predictors of Adverse Cardiovascular Events in Different Stages of Chronic Kidney Disease

Chronic kidney disease (CKD) is an important factor that contributes to the increase of all-cause morbidity and mortality in the group of non-communicable diseases, and it is also recognized as a strong and independent risk factor that contributes to cardiovascular disease (CVD). CVDs are a consequence of the action of a large number of risk factors among which are traditional and non-traditional. These risk factors have been the subject of a large number of studies which partially explained the unfavorable cardiovascular (CV) outcome of CKD patients. Therefore, valid studies about clinical and biohumoral predictors are of particular importance, especially in the early stages of renal disease, that is, in patients with creatinine clearance below 60 ml/min/1.73 m² when preventive measures are most effective. Among potential predictors of adverse CV outcome are biomarkers of inflammation (Interleukin-18—IL-18), oxidative stress (ischemia-modified albumin—IMA; superoxide dismutase—SOD), acute kidney injury (kidney injury molecule-1—KIM-1; neutrophil gelatinase–associated lipocalin—NGAL), and microribonucleic acids (specific microRNA-133a). In this review, we tried to confirm the relationship between risk factors of CKD and CVD and newer, less frequently examined biomarkers with the occurrence of incidental CV events in renal patients.

Blood-brain barrier and gut barrier dysfunction in chronic kidney disease with a focus on circulating biomarkers and tight junction proteins

Kidney failure and associated uraemia have implications for the cardiovascular system, brain, and blood–brain barrier (BBB). We aim to examine BBB disruption, by assessing brain-derived neurotropic factor (BDNF), neuron-specific enolase (NSE) levels, and gut-blood barrier (GBB) disruption by trimethylamine N-oxide (TMAO), in chronic kidney disease (CKD) patients. Additionally, endothelial tight-junction protein expressions and modulation via TMAO were assessed. Serum from chronic kidney disease (CKD) female and male haemodialysis (HD) patients, and controls, were used to measure BDNF and NSE by enzyme-linked immunosorbent assays, and TMAO by mass spectrometry. Immunofluorescent staining of subcutaneous fat biopsies from kidney transplant recipients, and controls, were used to measure microvascular expression of tight-junction proteins (claudin-5, occludin, JAM-1), and control microvasculature for TMAO effects. HD patients versus controls, had significantly lower and higher serum levels of BDNF and NSE, respectively. In CKD biopsies versus controls, reduced expression of claudin-5, occludin, and JAM-1 were observed. Incubation with TMAO significantly decreased expression of all tight-junction proteins in the microvasculature. Uraemia affects BBB and GBB resulting in altered levels of circulating NSE, BDNF and TMAO, respectively, and it also reduces expression of tight-junction proteins that confer BBB maintenance. TMAO serves as a potential candidate to alter BBB integrity in CKD.

Intestinal microbiota and kidney diseases

Large microbial communities reside in the gut as an endogenous organ and interact with the host physiology through symbiotic relationships, affecting health. Recent advances in high-throughput sequencing techniques have made it possible to better understand these complex microbial communities and their effects on hosts. Animal and clinical studies have provided considerable evidence to show that the microbiota plays an important role in chronic kidney disease, acute kidney injury, nephrolithiasis, and kidney transplantation by altering the functions of the intestinal barrier, regulating local and systemic inflammation, controlling production of metabolic components, and affecting immune responses. Although the exact mechanism underlying the microbial shift and its impact on disease progression remains uncertain, the kidney-gut interaction clearly plays a significant role in onset and progression of kidney disease and, therefore, holds promise as a therapeutic target. Here, we review recent literature pertaining to the bidirectional relationship between microbes and humans in various kidney diseases and discuss the future direction of microbial research in nephrology.

Soluble CD14 Levels in the Jackson Heart Study: Associations With Cardiovascular Disease Risk and Genetic Variants

[Figure: see text].

Intestinal microbiota and diabetic kidney diseases: the Role of microbiota and derived metabolites inmodulation of renal inflammation and disease progression

Diabetic kidney disease (DKD) represents a growing public health burden and is the leading cause of end-stage kidney diseases. In recent years, host-gut microbiota interactions have emerged as an integral part for host homeostasis. In the context of nephropathies, mounting evidence supports a bidirectional microbiota-kidney crosstalk, which becomes particularly manifest during progressive kidney dysfunction. Indeed, in chronic kidney disease (CKD), the "healthy" microbiota structure is disrupted and intestinal microbes produce large quantities of uremic solutes responsible for renal damage; on the other hand, the uremic state, fueled by reduced renal clearance, causes shifts in microbial metabolism and composition, hence creating a vicious cycle in which dysbiosis and renal dysfunction are progressively worsened. In this review, we will summarize the evidence from clinical/experimental studies concerning the occurrence of gut dysbiosis in diabetic and non-diabetic CKD, discuss the functional consequences of dysbiosis for CKD progression and debate putative therapeutic interventions targeting the intestinal microbiome.

Association of Plasma Soluble Vascular Cell Adhesion Molecule-1 and sCD14 With Mortality in HIV-1-Infected West African Adults With High CD4 Counts

BACKGROUND

Several biomarkers of inflammation and coagulation were reported to be associated with HIV disease progression in different settings. In this article, we report the association between 11 biomarkers and medium-term mortality in HIV-infected West African adults.

METHODS

In Temprano ANRS 12136, antiretroviral therapy (ART)-naive HIV-infected adults with high CD4 counts were randomly assigned either to start ART immediately or defer ART until the World Health Organization criteria were met. Participants who completed the 30-month trial follow-up were invited to participate in a posttrial phase. The posttrial phase end point was all-cause death. We used multivariate Cox proportional models to analyze the association between baseline plasma biomarkers [IL-1ra, IL-6, soluble vascular cell adhesion molecule 1 (sVCAM-1), sCD14, D-dimer, fibrinogen, IP-10, sCD163, albumin, high-sensitivity C-reactive protein, and 16S rDNA] and all-cause death in the Temprano participants randomized to defer ART.

RESULTS

Four hundred seventy-seven patients (median age 35 years, 78% women, and median CD4 count: 379 cells/mm) were randomly assigned to defer starting ART until the World Health Organization criteria were met. The participants were followed for 2646 person-years (median 5.8 years). In the follow-up, 89% of participants started ART and 30 died. In the multivariate analysis adjusted for the study center, sex, baseline CD4 count, isoniazid preventive therapy, plasma HIV-1 RNA, peripheral blood mononuclear cell HIV-1 DNA, and ART, the risk of death was significantly associated with baseline sVCAM-1 (≥1458 vs. <1458: adjusted hazard ratio 2.57, 95% confidence interval: 1.13 to 5.82) and sCD14 (≥2187 vs. <2187: adjusted hazard ratio 2.79, interquartile range 1.29-6.02) levels.

CONCLUSIONS

In these sub-Saharan African adults with high CD4 counts, pre-ART plasma sVCAM-1 and sCD14 levels were independently associated with mortality.

Gut-Derived Metabolites and Their Role in Immune Dysfunction in Chronic Kidney Disease

Several of the uremic toxins, which are difficult to remove by dialysis, originate from the gut bacterial metabolism. This opens opportunities for novel targets trying to decrease circulating levels of these toxins and their pathophysiological effects. The current review focuses on immunomodulatory effects of these toxins both at their side of origin and in the circulation. In the gut end products of the bacterial metabolism such as p-cresol, trimethylamine and H₂S affect the intestinal barrier structure and function while in the circulation the related uremic toxins stimulate cells of the immune system. Both conditions contribute to the pro-inflammatory status of patients with chronic kidney disease (CKD). Generation and/or absorption of these toxin precursors could be targeted to decrease plasma levels of their respective uremic toxins and to reduce micro-inflammation in CKD.

Impact of Gut Dysbiosis on Neurohormonal Pathways in Chronic Kidney Disease

Chronic kidney disease (CKD) is a worldwide major health problem. Traditional risk factors for CKD are hypertension, obesity, and diabetes mellitus. Recent studies have identified gut dysbiosis as a novel risk factor for the progression CKD and its complications. Dysbiosis can worsen systemic inflammation, which plays an important role in the progression of CKD and its complications such as cardiovascular diseases. In this review, we discuss the beneficial effects of the normal gut microbiota, and then elaborate on how alterations in the biochemical environment of the gastrointestinal tract in CKD can affect gut microbiota. External factors such as dietary restrictions, medications, and dialysis further promote dysbiosis. We discuss the impact of an altered gut microbiota on neuroendocrine pathways such as the hypothalamus⁻pituitary⁻adrenal axis, the production of neurotransmitters and neuroactive compounds, tryptophan metabolism, and the cholinergic anti-inflammatory pathway. Finally, therapeutic strategies including diet modification, intestinal alpha-glucosidase inhibitors, prebiotics, probiotics and synbiotics are reviewed.

Changes in the inflammatory and oxidative stress markers during a single hemodialysis session in patients with chronic kidney disease

BACKGROUND

Cardiovascular disease (CVD) is a common cause of morbidity and mortality in end-stage renal disease (ESRD) patients on hemodialysis (HD) among whom it is 5-20 times higher than in the general population. Some of the nontraditional risk factors such as oxidative stress and inflammation are related to the progress of CVD in HD patients. Several, but not all studies, reported that inflammatory and oxidative stress markers are increased during a single session of HD, mimicking changes that occur during acute immune activation. This study was taken up to evaluate the changes in the inflammatory and oxidative stress markers during a single HD session in patients with chronic kidney disease.

METHODS

Twenty-five ESRD patients on maintenance HD and 25 controls were included in the study. Blood samples were obtained from the patients before starting of hemodialysis (pre-HD) and after completion of hemodialysis (post-HD). The changes in serum Pentraxin-3, hs-CRP, malondialdehyde (MDA) and ferric reducing ability of plasma (FRAP) levels were measured in pre- and post-HD ESRD patients and compared with healthy control group.

RESULTS

This study found increased levels of Pentraxin-3, hs-CRP, MDA, and decreased level of FRAP in HD patients compared to controls.

CONCLUSIONS

Hemodialysis procedure contributes to inflammation and oxidative stress.

Circulating Bacterial Fragments as Cardiovascular Risk Factors in CKD

Cardiovascular disease (CVD) is a major cause of mortality and morbidity in patients with CKD. In the past decade, intestinal dysbiosis and altered gut epithelial barrier function are increasingly recognized in CKD. Uremic patients have slow intestinal transit time, impaired protein assimilation, and decreased consumption of dietary fiber. The use of multiple medications also may contribute to the proliferation of dysbiotic bacteria, which affect the barrier function of intestinal epithelium. In addition, fluid overload and uremic toxins per se directly reduce the gut barrier function. The major consequence of these alterations, the translocation of bacterial fragments from bowel lumen to systemic circulation, can lead to diverse biologic effects and probably represents an important nontraditional CVD risk factor in CKD. Among all bacterial fragments, endotoxin is the most well studied. Plasma endotoxin levels are markedly elevated in both patients with CKD and those on dialysis, and are associated with the systemic inflammatory state, accelerated atherosclerosis, and clinical CVD in patients on dialysis. Optimization of BP control and the use of ultrapure dialysate can reduce plasma endotoxin levels, with probable metabolic and cardiovascular benefits. The benefit of synbiotic therapy is not confirmed, although results from animal studies are impressive. The biologic effects and clinical relevance of other bacterial fragments, such as bacterial DNA fragments, are less well defined. Further studies are needed to delineate the pathogenic relation between circulating bacterial fragments and CVD, and to define the role of the plasma bacterial fragment level as a prognostic indicator of CKD.

Does Low-Protein Diet Influence the Uremic Toxin Serum Levels From the Gut Microbiota in Nondialysis Chronic Kidney Disease Patients?

OBJECTIVES

To evaluate the effects of low-protein diet (LPD) on uremic toxins and the gut microbiota profile in nondialysis chronic kidney disease (CKD) patients.

DESIGN AND METHODS

Longitudinal study with 30 nondialysis CKD patients (stage 3-4) undergoing LPD for 6 months. Adherence to the diet was evaluated based on the calculation of protein equivalent of nitrogen appearance from the 24-hour urine analysis. Good adherence to LPD was considered when protein intake was from 90% to 110% of the prescribed amount (0.6 g/kg/day). Food intake was analyzed by the 24-hour recall method. The anthropometric, biochemical and lipid profile parameters were measured according to standard methods. Uremic toxin serum levels (indoxyl sulfate, p-cresyl sulfate, indole-3-acetic acid) were obtained by reversed-phase high-performance liquid chromatography (RP-HPLC). Fecal samples were collected to evaluate the gut microbiota profile through polymerase chain reaction and denaturing gradient gel electrophoresis. Statistical analysis was performed by the SPSS 23.0 program software.

RESULTS

Patients who adhered to the diet (n = 14) (0.7 ± 0.2 g/kg/day) presented an improvement in renal function (nonsignificant) and reduction in total and low-density lipoprotein cholesterol (183.9 ± 48.5-155.7 ± 37.2 mg/dL, P = .01; 99.4 ± 41.3-76.4 ± 33.2 mg/dL, P = .01, respectively). After 6 months of nutricional intervention, p-cresyl sulfate serum levels were reduced significantly in patients who adhered to the LPD (19.3 [9.6-24.7] to 15.5 [9.8-24.1] mg/L, P = .03), and in contrast, the levels were increased in patients who did not adhere (13.9 [8.0-24.8] to 24.3 [8.1-39.2] mg/L, P = .004). In addition, using the denaturing gradient gel electrophoresis technique, it was observed change in the intestinal microbiota profile after LPD intervention in both groups, and the number of bands was positively associated with protein intake (r = 0.44, P = .04).

CONCLUSION

LPD seems be a good strategy to reduce the uremic toxins production by the gut microbiota in nondialysis CKD patients.

Structural and functional differences in gut microbiome composition in patients undergoing haemodialysis or peritoneal dialysis

Complications of end-stage renal disease (ESRD) are critically related to inflammation. The gut microbiome is a key driver of inflammation. Since dialysis modalities may differently influence the gut microbiome, we aimed to compare the effects of haemodialysis (HD) and peritoneal dialysis (PD) on patients' gut microbiome composition and function. We therefore studied faecal microbiome composition and function as well as inflammation and gut permeability in 30 patients with ESRD (15 HD, 15 PD) and compared to 21 healthy controls. We found an increase in potentially pathogenic species and a decrease in beneficial species in patients on HD and to a lesser extend in patients on PD when compared to controls. These changes in taxonomic composition also resulted in differences in predicted metagenome functions of the faecal microbiome. In HD but not in PD, changes in microbiome composition were associated with an increase in c-reactive protein (CRP) but not with intestinal inflammation or gut permeability. In conclusion microbiome composition in ESRD differs from healthy controls but also between modes of dialysis. These differences are associated with systemic inflammation and cannot completely be explained by dialysis vintage. The mode of renal replacement therapy seems to be an important driver of dysbiosis in ESRD.

The Associations of Endotoxemia With Systemic Inflammation, Endothelial Activation, and Cardiovascular Outcome in Kidney Transplantation

OBJECTIVE

Cardiovascular disease is the leading cause of death in kidney transplant recipients (KTRs), yet incompletely accountable by traditional risk factors. Inflammation is an unconventional cardiovascular risk factor, with gut-derived endotoxemia potentially driving inflammation and endothelial disease. Comparable data are lacking in kidney transplantation. This study investigated the associations of endotoxemia with inflammation, endothelial activation, and 5-year cardiovascular events in KTRs. Determinants of endotoxemia were also explored.

DESIGN AND METHODS

This is a single-center cross-sectional study with prospective follow-up from a prevalent cohort of 128 KTRs.

MAIN OUTCOME MEASURES

Demographic, nutritional and clinical predictors of inflammation (high-sensitivity C-reactive protein [hsCRP]), endothelial activation (sE-selectin), and endotoxemia (endotoxin) were assessed. Follow-up data on 5-year cardiovascular event rates were collected.

RESULTS

Endotoxemia (P = .03), reduced 25-hydroxyvitamin D (P = .04), high fructose intake (P < .001), decreased fiber intake (P < .001), and abdominal obesity (P = .002) were independently associated with elevated hsCRP. In turn, endotoxemia (P = .007) and increasing hsCRP (P = .02) were both independently associated with raised sE-selectin. Furthermore, endotoxemia predicted increased cardiovascular event rate (P = .02), independent of hsCRP and a global measure of cardiovascular risk estimated by a validated algorithm of 7-year risk for major adverse cardiac events in kidney transplantation. Determinants of endotoxemia included reduced 25-hydroxyvitamin D (P < .001), hypertriglyceridemia (P < .001), increased fructose intake (P = .01), and abdominal obesity (P = .01).

CONCLUSIONS

Endotoxemia in KTRs contributes to inflammation, endothelial activation, and increased cardiovascular events. This study highlights the clinical relevance of endotoxemia in KTRs, suggesting future interventional targets.

Inflammation and premature aging in advanced chronic kidney disease

Systemic inflammation in end-stage renal disease is an established risk factor for mortality and a catalyst for other complications, which are related to a premature aging phenotype, including muscle wasting, vascular calcification, and other forms of premature vascular disease, depression, osteoporosis, and frailty. Uremic inflammation is also mechanistically related to mechanisms involved in the aging process, such as telomere shortening, mitochondrial dysfunction, and altered nutrient sensing, which can have a direct effect on cellular and tissue function. In addition to uremia-specific causes, such as abnormalities in the phosphate-Klotho axis, there are remarkable similarities between the pathophysiology of uremic inflammation and so-called "inflammaging" in the general population. Potentially relevant, but still somewhat unexplored in this respect, are abnormal or misplaced protein structures, as well as abnormalities in tissue homeostasis, which evoke danger signals through damage-associated molecular patterns, as well as the senescence-associated secretory phenotype. Systemic inflammation, in combination with the loss of kidney function, can impair the resilience of the body to external and internal stressors by reduced functional and structural tissue reserves, and by impairing normal organ crosstalk, thus providing an explanation for the greatly increased risk of homeostatic breakdown in this population. In this review, the relationship between uremic inflammation and a premature aging phenotype, as well as potential causes and consequences, are discussed.

Alkaline phosphatase: a novel treatment target for cardiovascular disease in CKD

Cardiovascular disease is the main cause of early death in the settings of chronic kidney disease (CKD), type 2 diabetes mellitus (T2DM), and ageing. Cardiovascular events can be caused by an imbalance between promoters and inhibitors of mineralization, which leads to vascular calcification. This process is akin to skeletal mineralization, which is carefully regulated and in which isozymes of alkaline phosphatase (ALP) have a crucial role. Four genes encode ALP isozymes in humans. Intestinal, placental and germ cell ALPs are tissue-specific, whereas the tissue-nonspecific isozyme of ALP (TNALP) is present in several tissues, including bone, liver and kidney. TNALP has a pivotal role in bone calcification. Experimental overexpression of TNALP in the vasculature is sufficient to induce vascular calcification, cardiac hypertrophy and premature death, mimicking the cardiovascular phenotype often found in CKD and T2DM. Intestinal ALP contributes to the gut mucosal defence and intestinal and liver ALPs might contribute to the acute inflammatory response to endogenous or pathogenic stimuli. Here we review novel mechanisms that link ALP to vascular calcification, inflammation, and endothelial dysfunction in kidney and cardiovascular diseases. We also discuss new drugs that target ALP, which have the potential to improve cardiovascular outcomes without inhibiting skeletal mineralization.

Targeting Immunity in End-Stage Renal Disease

BACKGROUND

Despite the stable incidence of end-stage renal disease (ESRD), it continues to be associated with an unacceptably high cardiovascular risk.

SUMMARY

ESRD is characterized by enhanced oxidative stress and severe inflammation, which boost cardiovascular risk, thus increasing cardiovascular-associated mortality rate. While substantial effort has been made in the technological innovation of dialytic techniques, few significant advances have been made to reduce inflammation in patients with ESRD. Indeed, this contrasts with the extensive scientific breakthroughs made in the basic field of science in targeting inflammation. There is thus a pressing need for clinical trials to test the effect of reducing inflammation in patients with ESRD. Here, we will revisit the negative effect of ESRD on inflammation and explore the impact of enhanced inflammation on cardiovascular outcomes and survival in patients with ESRD. Finally, we will discuss the need for clinical trials that target inflammation in ESRD, as well as weigh potential disadvantages and offer novel innovative approaches. Key Message: We will try to understand why the issue of inflammation has not been successfully addressed thus far in patients with ESRD, while at the same time weighing the potential disadvantages and offering novel innovative approaches for targeting inflammation in patients with ESRD.

Intestinal Barrier Disturbances in Haemodialysis Patients: Mechanisms, Consequences, and Therapeutic Options

There is accumulating evidence that the intestinal barrier and the microbiota may play a role in the systemic inflammation present in HD patients. HD patients are subject to a number of unique factors, some related to the HD process and others simply to the uraemic milieu but with common characteristic that they can both alter the intestinal barrier and the microbiota. This review is intended to provide an overview of the current methods for measuring such changes in HD patients, the mechanisms behind these changes, and potential strategies that may mitigate these modifications. Lastly, intradialytic exercise is an increasingly employed intervention in HD patients; however the potential implications that this may have for the intestinal barrier are not known; therefore future research directions are also covered.

Gut microbiome in chronic kidney disease: challenges and opportunities

More than 100 trillion microbial cells that reside in the human gut heavily influence nutrition, metabolism, and immune function of the host. Gut dysbiosis, seen commonly in patients with chronic kidney disease (CKD), results from qualitative and quantitative changes in host microbiome profile and disruption of gut barrier function. Alterations in gut microbiota and a myriad of host responses have been implicated in progression of CKD, increased cardiovascular risk, uremic toxicity, and inflammation. We present a discussion of dysbiosis, various uremic toxins produced from dysbiotic gut microbiome, and their roles in CKD progression and complications. We also review the gut microbiome in renal transplant, highlighting the role of commensal microbes in alteration of immune responses to transplantation, and conclude with therapeutic interventions that aim to restore intestinal dysbiosis.

Is Endotoxemia in Stable Hemodialysis Patients an Artefact? Limitations of the Limulus Amebocyte Lysate Assay and Role of (1→3)-β-D Glucan

Background

Elevated blood endotoxin levels are frequently reported in the dialysis population and are strongly linked with inflammation, a major predictor of mortality. Virtually all studies have employed the Limulus Amoebocyte Lysate (LAL) assay to detect endotoxin. However this assay is not endotoxin-specific and can be activated by (1→3)-β-glucan (BG), a component of fungal cell walls leading to false positive signals. Very few studies have taken account of this. We examined the influence of BG-based activation of the LAL assay on the detection of endotoxemia in this setting.

Method

We measured plasma endotoxin levels in 50 hemodialysis patients with and without the use of BG-blocking buffers. These buffers inhibit BG activation of the LAL assay to ensure that any signal detected is endotoxin-specific. Blood samples were measured for BG, interleukin-6 (IL-6), tumor necrosis factor-alfa (TNF-α) to examine the association between endotoxin signals, BG and inflammation.

Results

Endotoxin signals were detected in 50% of patients. On repeat measurement with a BG-blocking buffer, all detected endotoxin signals were extinguished. No patient had detectable endotoxemia. Plasma BG levels were significantly elevated in 58% of patients and were higher in those with detectable endotoxin signals using the LAL assay without BG-blocking buffers (78vs.54pg/mL;p<0.001). Endotoxin signal and BG levels did not correlate with levels of TNF-α or IL-6.

Conclusion

Use of the LAL assay for blood endotoxin detection in dialysis patients has its limitations due to high blood BG. Endotoxemia frequently reported in non-infected hemodialysis patients may be artefactual due to BG interference.

Mode of renal replacement therapy determines endotoxemia and neutrophil dysfunction in chronic kidney disease

Bacterial infection and sepsis are common complications of chronic kidney disease (CKD). A vicious cycle of increased gut permeability, endotoxemia, inadequate activation of the innate immune system and resulting innate immune dysfunction is hypothesized. We assessed endotoxemia, neutrophil function and its relation to oxidative stress, inflammation and gut permeability in patients with CKD grade 3–5 without renal replacement therapy (CKD group, n = 57), patients with CKD stage 5 undergoing haemodialysis (HD, n = 32) or peritoneal dialysis (PD, n = 28) and patients after kidney transplantation (KT, n = 67) in a cross-sectional observational study. In HD patients, endotoxin serum levels were elevated and neutrophil phagocytic capacity was decreased compared to all other groups. Patients on HD had a significantly higher mortality, due to infections during follow up, compared to PD (p = 0.022). Oxidative stress, neutrophil energy charge, systemic inflammation and gut permeability could not completely explain these differences. Our findings suggest that dialysis modality and not renal function per se determine the development of neutrophil dysfunction and endotoxemia in CKD-patients. HD patients are particularly prone to neutrophil dysfunction and endotoxemia whereas neutrophil function seems to improve after KT. Multi-target approaches are therefore warranted to improve neutrophil function and potentially reduce the rate of infections with patients undergoing haemodialysis.

A comparative study of blood endotoxin detection in haemodialysis patients

BACKGROUND

Endotoxemia is commonly reported in patients receiving haemodialysis and implicated in the pathogenesis of systemic inflammation. The Limulus Amoebocyte Lysate (LAL) assay is the most commonly used blood endotoxin detection assay. Two kinetic variations of the assay are commercially available - the turbidimetric and chromogenic assay, it is unknown which assay is superior for endotoxin detection in uremic patients. Selection of the optimum LAL technique for endotoxin detection in haemodialysis patients is important to further understanding of the sequela of endotoxemia and development of endotoxin-lowering strategies in this population.

METHOD

A turbidimetric and chromogenic LAL assay from the same manufacturer were directly compared. We investigated the ability of both LAL assays to detect endotoxin in uremic plasma. Plasma samples from haemodialysis patients and healthy controls were spiked with endotoxin and percentage spike recovery for the chromogenic and turbidimetric assay was determined. Assay accuracy and precision were compared between both LAL assays.

RESULTS

The turbidimetric assay had greater accuracy than the chromogenic assay. Spike recovery was 113.8 % vs. 53.8 % for the turbidimetric and chromogenic assay respectively. Assay bias was higher in the chromogenic assay (-0.384EU/mL vs. 0.011EU/mL). The turbidimetric assay demonstrated greater precision compared to the chromogenic assay. Coefficient of variation ranged from 4.5 to 24.1 % for the turbidimetric assay and 25.8-26.5 % for the chromogenic assay.

CONCLUSION

The study findings suggest that the kinetic turbidimetric LAL assay has greater accuracy and precision than the chromogenic assay and is the optimum LAL technique for endotoxin detection in haemodialysis patients, though these findings should be verified using LAL reagents from other sources.

Soluble CD14 and fracture risk

Soluble CD14 (sCD14) is an inflammatory marker associated with osteoclasts. Using Cox proportional hazards models, we found a positive association between plasma levels of sCD14 and risk of incident fracture among participants in the Cardiovascular Health Study. sCD14 may be useful in identifying those at risk for fracture.

INTRODUCTION

Soluble CD14, a proinflammatory cytokine, is primarily derived from macrophages/monocytes that can differentiate into osteoclasts. The purpose of this study was to examine the relationship between sCD14 levels and osteoporotic fractures.

METHODS

In the Cardiovascular Health Study, 5462 men and women had sCD14 levels measured at baseline. Incident hip fractures (median follow-up time 12.5 years) and incident composite fractures (defined as the first hip, pelvis, humerus, or distal radius fracture, median follow-up 8.6 years) were identified from hospital discharge summaries and/or Medicare claims data. Cox proportional hazards models were used to model the association between sCD14 levels and time to incident hip or composite fracture, overall and as a function of race and gender.

RESULTS

In unadjusted models, there was a positive association between sCD14 levels (per 1 standard deviation increase, i.e., 361.6 ng/mL) and incident hip (HR, 1.26; 95 % CI, 1.17, 1.36) and composite (HR, 1.20; 95 % CI, 1.12, 1.28) fractures. When models were fully adjusted for demographics, lifestyle factors, and medication use, these associations were no longer significant. However, in whites, the association of sCD14 levels with hip fractures remained significant in fully adjusted models (HR, 1.11; 95 % CI, 1.01-1.23). Associations of sCD14 levels with hip and composite fracture did not differ between men and women.

CONCLUSIONS

In this large cohort of community-dwelling older adults, higher sCD14 levels were associated with an increased risk of incident hip fractures in whites.

Role of the Gut Microbiome in Uremia: A Potential Therapeutic Target

Also known as the "second human genome," the gut microbiome plays important roles in both the maintenance of health and the pathogenesis of disease. The symbiotic relationship between host and microbiome is disturbed due to the proliferation of dysbiotic bacteria in patients with chronic kidney disease (CKD). Fermentation of protein and amino acids by gut bacteria generates excess amounts of potentially toxic compounds such as ammonia, amines, thiols, phenols, and indoles, but the generation of short-chain fatty acids is reduced. Impaired intestinal barrier function in patients with CKD permits translocation of gut-derived uremic toxins into the systemic circulation, contributing to the progression of CKD, cardiovascular disease, insulin resistance, and protein-energy wasting. The field of microbiome research is still nascent, but is evolving rapidly. Establishing symbiosis to treat uremic syndrome is a novel concept, but if proved effective, it will have a significant impact on the management of patients with CKD.

Serum Trimethylamine-N-Oxide Is Strongly Related to Renal Function and Predicts Outcome in Chronic Kidney Disease

Background

The microbial metabolite Trimethylamine-N-oxide (TMAO) has been linked to adverse cardiovascular outcome and mortality in the general population.

Objective

To assess the contribution of TMAO to inflammation and mortality in chronic kidney disease (CKD) patients ranging from mild-moderate to end-stage disease and 1) associations with glomerular filtration rate (GFR) 2) effect of dialysis and renal transplantation (Rtx) 3) association with inflammatory biomarkers and 4) its predictive value for all-cause mortality.

Methods

Levels of metabolites were quantified by a novel liquid chromatography/tandem mass spectrometry-based method in fasting plasma samples from 80 controls and 179 CKD 3–5 patients. Comorbidities, nutritional status, biomarkers of inflammation and GFR were assessed.

Results

GFR was the dominant variable affecting TMAO (β = -0.41; p<0.001), choline (β = -0.38; p<0.001), and betaine (β = 0.45; p<0.001) levels. A longitudinal study of 74 CKD 5 patients starting renal replacement therapy demonstrated that whereas dialysis treatment did not affect TMAO, Rtx reduced levels of TMAO to that of controls (p<0.001). Following Rtx choline and betaine levels continued to increase. In CKD 3–5, TMAO levels were associated with IL-6 (Rho = 0.42; p<0.0001), fibrinogen (Rho = 0.43; p<0.0001) and hsCRP (Rho = 0.17; p = 0.022). Higher TMAO levels were associated with an increased risk for all-cause mortality that remained significant after multivariate adjustment (HR 4.32, 95% CI 1.32–14.2; p = 0.016).

Conclusion

Elevated TMAO levels are strongly associated with degree of renal function in CKD and normalize after renal transplantation. TMAO levels correlates with increased systemic inflammation and is an independent predictor of mortality in CKD 3–5 patients.

The Role of the Gut Microbiome on Chronic Kidney Disease

Chronic kidney disease (CKD) is estimated to affect nearly 500 million people worldwide and cardiovascular (CV) disease is a major cause of death in this population. However, therapeutic interventions targeting traditional CV risks are not effective at lowering the incidence of CV events or at delaying the progression of the disease in CKD patients. In recent years, disturbances of normal gut microbiome were recognized in the pathogenesis of diverse chronic diseases. Gut dysbiosis is being unraveled in CKD and pointed as a nontraditional risk factor for CV risk and CKD progression. The most often reported changes in gut microbiome in CKD are related to the lower levels of Bifidobacteriaceae and Lactobacillaceae and to higher levels of Enterobacteriaceae. Although metagenomics brought us an amplified vision on the microbial world that inhabits the human host, it still lacks the sensitivity to characterize the microbiome up to species level, not revealing alterations that occur within specific genus. Here, we review the current state-of-the-art concerning gut dysbiosis in CKD and its role in pathophysiological mechanisms in CKD, particularly in relation with CV risk. Also, the strategies towards prevention and treatment of gut dysbiosis in CKD progression will be discussed.

Associations of Soluble CD14 and Endotoxin with Mortality, Cardiovascular Disease, and Progression of Kidney Disease among Patients with CKD

BACKGROUND AND OBJECTIVES

CD14 plays a key role in the innate immunity as pattern-recognition receptor of endotoxin. Higher levels of soluble CD14 (sCD14) are associated with overall mortality in hemodialysis patients. The influence of kidney function on plasma sCD14 levels and its relationship with adverse outcomes in patients with CKD not yet on dialysis is unknown. This study examines the associations between plasma levels of sCD14 and endotoxin with adverse outcomes in patients with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We measured plasma levels of sCD14 and endotoxin in 495 Leuven Mild-to-Moderate CKD Study participants. Mild-to-moderate CKD was defined as presence of kidney damage or eGFR<60 ml/min per 1.73 m(2) for ≥3 months, with exclusion of patients on RRT. Study participants were enrolled between November 2005 and September 2006.

RESULTS

Plasma sCD14 was negatively associated with eGFR (ρ=-0.34, P<0.001). During a median follow-up of 54 (interquartile range, 23-58) months, 53 patients died. Plasma sCD14 was predictive of mortality, even after adjustment for renal function, Framingham risk factors, markers of mineral bone metabolism, and nutritional and inflammatory parameters (hazard ratio [HR] per SD higher of 1.90; 95% confidence interval [95% CI],1.32 to 2.74; P<0.001). After adjustment for the same risk factors, plasma sCD14 was also a predictor of cardiovascular disease (HR, 1.30; 95% CI, 1.00 to 1.69; P=0.05). Although plasma sCD14 was associated with progression of CKD, defined as reaching ESRD or doubling of serum creatinine in models adjusted for CKD-specific risk factors (HR, 1.24; 95% CI, 1.01 to 1.52; P=0.04), significance was lost when adjusted for proteinuria (HR, 1.19; 95% CI, 0.96 to 1.48; P=0.11). There was neither correlation between plasma endotoxin and sCD14 (ρ=-0.06, P=0.20) nor was endotoxin independently associated with adverse outcome during follow-up.

CONCLUSIONS

Plasma sCD14 is elevated in patients with decreased kidney function and associated with mortality and cardiovascular disease in patients with CKD not yet on dialysis.

Use of sevelamer in chronic kidney disease: beyond phosphorus control

Sevelamer is a non-calcium phosphate binder used in advanced chronic kidney disease (CKD) and in dialysis for hyperphosphataemia control. Several experimental, observational studies and clinical trials have shown that sevelamer has pleiotropic effects, beyond hyperphosphataemia control, including actions on inflammation, oxidative stress, lipid profile and atherogenesis, vascular calcification, endothelial dysfunction and the reduction of several uremic toxins. This is the biological basis for its global effect on cardiovascular morbidity and mortality in patients with chronic kidney disease. This review focuses on these pleiotropic actions of sevelamer and their impact on cardiovascular health, with the experience published after more than ten years of clinical expertise.

Altered intestinal microbial flora and impaired epithelial barrier structure and function in CKD: the nature, mechanisms, consequences and potential treatment

Chronic kidney disease (CKD) results in systemic inflammation and oxidative stress which play a central role in CKD progression and its adverse consequences. Although many of the causes and consequences of oxidative stress and inflammation in CKD have been extensively explored, little attention had been paid to the intestine and its microbial flora as a potential source of these problems. Our recent studies have revealed significant disruption of the colonic, ileal, jejunal and gastric epithelial tight junction in different models of CKD in rats. Moreover, the disruption of the epithelial barrier structure and function found in uremic animals was replicated in cultured human colonocytes exposed to uremic human plasma in vitro We have further found significant changes in the composition and function of colonic bacterial flora in humans and animals with advanced CKD. Together, uremia-induced impairment of the intestinal epithelial barrier structure and function and changes in composition of the gut microbiome contribute to the systemic inflammation and uremic toxicity by accommodating the translocation of endotoxin, microbial fragments and other noxious luminal products in the circulation. In addition, colonic bacteria are the main source of several well-known pro-inflammatory uremic toxins such as indoxyl sulfate, p-cresol sulfate, trimethylamine-N-oxide and many as-yet unidentified retained compounds in end-stage renal disease patients. This review is intended to provide an overview of the effects of CKD on the gut microbiome and intestinal epithelial barrier structure and their role in the pathogenesis of systemic inflammation and uremic toxicity. In addition, potential interventions aimed at mitigating these abnormalities are briefly discussed.

Endotoxin detection in end-stage kidney disease

AIMS

Endotoxin detection assays are not validated for use in end-stage kidney disease (ESKD). We investigated the accuracy and precision of the kinetic turbidimetric Limulus amoebocyte lysate (LAL) assay to detect endotoxin in plasma from patients with ESKD. Optimisation of endotoxin recovery from plasma using the detergent Tween 80 was also explored.

METHODS

Plasma samples from 7 patients with ESKD and 7 healthy subjects were spiked with different concentrations of endotoxin. Repeated measurements for endotoxin at each level of spike were performed to assess the accuracy and precision of spike recovery. Endotoxin recovery in plasma samples diluted in Tween 80 and water was compared.

RESULTS

Mean endotoxin spike recovery was 111.6% and 125.2% in ESKD and healthy subjects, respectively. There was no statistical difference in spike recovery between ESKD and healthy plasma. Precision of the LAL assay in plasma spiked with low (0.05 EU/mL) and high (0.5 EU/mL) concentration of endotoxin spikes was 24.1% and 8.9%, respectively. The use of Tween 80 as a diluent for plasma significantly improved spike recovery in ESKD plasma (100.1% vs 70.4%, p<0.001).

CONCLUSIONS

The kinetic LAL turbidimetric assay is a valid tool for the detection of blood endotoxin in patients with ESKD, although in blood specimens with low-level endotoxemia (≤0.05 EU/mL) the assay may be less accurate and precise. Tween 80 can be used as a diluent to optimise recovery of endotoxin in ESKD plasma.

Synthesis and biological evaluation of novel indole-2-one and 7-aza-2-oxindole derivatives as anti-inflammatory agents

Sepsis, a typically acute inflammatory disease, is the biggest cause of death in ICU (intensive care unit). Novel anti-inflammatory alternatives are still in urgent need. In this study, we designed and synthesized 30 indole-2-one and 7-aza-2-oxindole derivatives based on the skeleton of tenidap, and their anti-inflammatory activity was determined by evaluating the inhibitory potency against lipopolysaccharide (LPS)-stimulated tumor necrosis factor (TNF)-α and interleukin (IL)-6 release in RAW264.7 macrophages. Quantitative SAR (structure-activity relationship) analysis revealed that a high molecular polarizability and low lipid/water partition coefficient (ALogP) in indole-2-one are beneficial for anti-inflammatory activity. Moreover, compounds 7i and 8e inhibited the expression of TNF-α, IL-6, COX-2, PGES, and iNOS in LPS-stimulated macrophages, and 7i exhibited a significant protection from LPS-induced septic death in mouse models. These data present a series of new indole-2-one compounds with potential therapeutic effects in acute inflammatory diseases.

Endotoxemia in end-stage kidney disease

Chronic unexplained inflammation remains a prevalent and clinically significant problem for patients with end-stage kidney disease (ESKD), especially in the dialysis population. The causes of persistent inflammation are likely to be multifactorial, but the underlying mechanisms remain to be elucidated. Endotoxins are reported to play a significant role in the pathogenesis of inflammation in patients with ESKD. However, blood endotoxin measurement with the Limulus amoebocyte lysate (LAL) assay is difficult with current detection systems. The reported degree and prevalence of endotoxemia varies in the literature. There are questions as to whether endotoxemia is truly present; whether the varied findings are due to methodological issues with the LAL assay and whether any endotoxemia that might be present plays a role in chronic inflammation frequently observed in ESKD patients. This review will discuss the challenges of accurate blood endotoxin detection, the potential source of blood endotoxins, and the significance of endotoxemia to patient with ESKD.

European Training and Research in Peritoneal Dialysis: scientific objectives, training, implementation and impact of the programme

BACKGROUND

Peritoneal dialysis (PD) offers many advantages over hospital-based haemodialysis, including better quality of life. Despite this, there is a general under-utilisation of PD in Europe, which, to some extent, can be attributed to a lack of knowledge and education amongst renal clinicians and nurses.

OBJECTIVES

The specific aim of the European Training and Research in Peritoneal Dialysis (EuTRiPD) programme is to address this lack of knowledge, to develop a minimum of five biomarkers that allow the prediction of outcome in PD and three therapeutic treatments to improve outcome in PD.

APPROACH

EuTRiPD is a EU-wide consortium with clinical, academic and commercial partners set up to address this knowledge gap. By training through research and close collaboration between academic and commercial entities we hope to improve the outcome and uptake of PD. It is the goal of EuTRiPD to improve the currently hampered diagnostic therapeutic developments in renal replacement therapy (RRT) and structure existing high-quality PD-related research across Europe.

CONCLUSION

It is hoped that EuTRiPD can and will have a significant impact on socio-economic and scientific aspects of PD. It is the aim for EuTRiPD to boost the uptake of PD throughout Europe by making PD the obvious choice for patients.

The gut microbiome, kidney disease, and targeted interventions

The human gut harbors >100 trillion microbial cells, which influence the nutrition, metabolism, physiology, and immune function of the host. Here, we review the quantitative and qualitative changes in gut microbiota of patients with CKD that lead to disturbance of this symbiotic relationship, how this may contribute to the progression of CKD, and targeted interventions to re-establish symbiosis. Endotoxin derived from gut bacteria incites a powerful inflammatory response in the host organism. Furthermore, protein fermentation by gut microbiota generates myriad toxic metabolites, including p-cresol and indoxyl sulfate. Disruption of gut barrier function in CKD allows translocation of endotoxin and bacterial metabolites to the systemic circulation, which contributes to uremic toxicity, inflammation, progression of CKD, and associated cardiovascular disease. Several targeted interventions that aim to re-establish intestinal symbiosis, neutralize bacterial endotoxins, or adsorb gut-derived uremic toxins have been developed. Indeed, animal and human studies suggest that prebiotics and probiotics may have therapeutic roles in maintaining a metabolically-balanced gut microbiota and reducing progression of CKD and uremia-associated complications. We propose that further research should focus on using this highly efficient metabolic machinery to alleviate uremic symptoms.

The Th17/Treg ratio, IL-1RA and sCD14 levels in primary HIV infection predict the T-cell activation set point in the absence of systemic microbial translocation

Impairment of the intestinal barrier and subsequent microbial translocation (MT) may be involved in chronic immune activation, which plays a central role in HIV pathogenesis. Th17 cells are critical to prevent MT. The aim of the study was to investigate, in patients with primary HIV infection (PHI), the early relationship between the Th17/Treg ratio, monocyte activation and MT and their impact on the T-cell activation set point, which is known to predict disease progression. 27 patients with early PHI were included in a prospective longitudinal study and followed-up for 6 months. At baseline, the Th17/Treg ratio strongly negatively correlated with the proportion of activated CD8 T cells expressing CD38/HLA-DR or Ki-67. Also, the Th17/Treg ratio was negatively related to viral load and plasma levels of sCD14 and IL-1RA, two markers of monocyte activation. In untreated patients, the Th17/Treg ratio at baseline negatively correlated with CD8 T-cell activation at month 6 defining the T-cell activation set point (% HLA-DR(+)CD38(+) and %Ki-67(+)). Soluble CD14 and IL-1RA plasma levels also predicted the T-cell activation set point. Levels of I-FABP, a marker of mucosal damages, were similar to healthy controls at baseline but increased at month 6. No decrease in anti-endotoxin core antibody (EndoCAb) and no peptidoglycan were detected during PHI. In addition, 16S rDNA was only detected at low levels in 2 out 27 patients at baseline and in one additional patient at M6. Altogether, data support the hypothesis that T-cell and monocyte activation in PHI are not primarily driven by systemic MT but rather by viral replication. Moreover, the "innate immune set point" defined by the early levels of sCD14 and IL-1RA might be powerful early surrogate markers for disease progression and should be considered for use in clinical practice.

CKD impairs barrier function and alters microbial flora of the intestine: a major link to inflammation and uremic toxicity

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is associated with oxidative stress and inflammation which contribute to progression of kidney disease and its numerous complications. Until recently, little attention had been paid to the role of the intestine and its microbial flora in the pathogenesis of CKD-associated inflammation. This article is intended to provide an over view of the impact of uremia on the structure and function of the gut and its microbial flora and their potential link to the associated systemic inflammation.

RECENT FINDINGS

Recent studies conducted in the author's laboratories have demonstrated marked disintegration of the colonic epithelial barrier structure and significant alteration of the colonic bacterial flora in humans and animals with advanced CKD. The observed disruption of the intestinal epithelial barrier complex can play an important part in the development of systemic inflammation by enabling influx of endotoxin and other noxious luminal contents into the systemic circulation. Similarly via disruption of the normal symbiotic relationship and production, absorption and retention of noxious products, alteration of the microbial flora can contribute to systemic inflammation and uremic toxicity. In fact recent studies have documented the role of colonic bacteria as the primary source of several well known pro-inflammatory/pro-oxidant uremic toxins as well as many as-yet unidentified retained compounds.

SUMMARY

CKD results in disruption of the intestinal barrier structure and marked alteration of its microbial flora - events that play a major role in the pathogenesis of inflammation and uremic toxicity.

Endotoxin binding by sevelamer: potential impact on nutritional status

Patients on hemodialysis (HD) have a high burden of chronic inflammation induced associated with multiple comorbidities including poor nutritional status. Endotoxin (ET) is a Gram-negative bacterial cell wall component and a potent stimulus for innate immune system activation leading to the transcription of proinflammatory cytokines (e.g., IL-1, IL-6, and TNFα) that adversely affect protein metabolism and nutrition. Several cross-sectional observational studies have found that elevated serum ET concentrations in hemodialysis patients are associated with lower serum albumin, higher proinflammatory cytokine, and C-reactive protein concentrations. Possible sources of ET in the systemic circulation are bacterial translocation from the gastrointestinal tract and iron supplementation, potentially leading to intestinal bacterial overgrowth. Sevelamer is a nonabsorbable hydrogel approved for use as a phosphate binder in HD patients. Reductions in serum ET concentrations in hemodialysis patients have been observed with sevelamer therapy in observational studies and the few published interventional studies. Reduction of ET concentrations was associated with concomitant reductions in TNFα, IL-6, and CRP and improvement in serum albumin in the majority of these small studies. Additional studies are needed to evaluate the potential effects of sevelamer treatment on nutritional status in chronic kidney disease (CKD) patients with elevated ET.

Pentraxin 3, a sensitive early marker of hemodialysis-induced inflammation

BACKGROUND/AIMS

The purpose of this investigation was to determine if the long pentraxin 3 (PTX-3) may be a useful marker of intradialytic inflammation since it is rapidly released in the vasculature.

METHODS

PTX-3, interleukin-6, tumor necrosis factor-α and C-reactive protein were measured before and during a hemodialysis session in 22 patients and compared with healthy subjects. The effect of dialysis with low-flux, high-flux membranes and hemodiafiltration on the inflammatory response was compared in 11 patients.

RESULTS

C-reactive protein and interleukin-6 levels did not change, while a modest decrease in tumor necrosis factor-α was observed during hemodialysis. The plasma PTX-3 concentration was significantly increased (p < 0.001) after 60 min and peaked at 180 min during hemodialysis. There was no difference in the intradialytic increase in PTX-3 using different dialysis membranes and modalities.

CONCLUSION

PTX-3 stands out as a rapid and sensitive marker of hemodialysis-induced inflammation. Membrane flux and hemodiafiltration did not alter the inflammatory response.

Uremic plasma impairs barrier function and depletes the tight junction protein constituents of intestinal epithelium

BACKGROUND

Chronic kidney disease (CKD) causes intestinal barrier dysfunction which by allowing influx of endotoxin and other noxious products contributes to the CKD-associated systemic inflammation and uremic toxicity. We have recently shown that intestinal barrier dysfunction in CKD animals is due to degradation of transcellular (claudin-1 and occludin) and intracellular (ZO1) constituents of epithelial tight junction (TJ). This study determined whether CKD-associated disruption of TJ is mediated by retained uremic toxins/metabolites and, if so, whether they are removed by hemodialysis.

METHODS

The TJ-forming human enterocytes (T84 cells) were seeded on the Transwell plates and utilized when transepithelial electrical resistance (TER) exceeded 1,000 mΩ/cm(2) to ensure full polarization and TJ formation. The cells were then incubated for 24 h in media containing 10% pre- or posthemodialysis plasma from end-stage renal disease (ESRD) patients or healthy individuals. TER was then measured and cells were processed for Western blot and immunohistological analyses.

RESULTS

Compared with the control plasma, incubation in media containing predialysis plasma from ESRD patients resulted in a marked drop in TER pointing to increased epithelial permeability. This was accompanied by significant reductions in claudin-1 (85%), occludin (15%), and ZO1 (70%) abundance. The severity of TJ damage and dysfunction was significantly less in cells exposed to the postdialysis in comparison to predialysis plasma. These findings point to the presence of as-yet unidentified product(s) in the uremic plasma capable of depleting epithelial TJ.

CONCLUSIONS

Exposure to uremic milieu damages the intestinal epithelial TJ and impairs its barrier function, events which are mediated by agents which are partially removed by hemodialysis.

Association between albuminuria, kidney function, and inflammatory biomarker profile in CKD in CRIC

BACKGROUND AND OBJECTIVES

Increased risk of mortality in patients with CKD has been attributed to inflammation. However, the association between kidney function, albuminuria, and biomarkers of inflammation has not been examined in a large cohort of CKD patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study measured the plasma levels of IL-1β, IL-1 receptor antagonist (IL-1RA), IL-6, TNF-α, TGF-β, high-sensitivity C-reactive protein (hs-CRP), fibrinogen, and serum albumin in 3939 participants enrolled in the Chronic Renal Insufficiency Cohort study between June 2003 and September 2008. An inflammation score was established based on plasma levels of IL-1β, IL-6, TNF-α, hs-CRP, and fibrinogen. Estimated GFR (eGFR) and serum cystatin C were used as measures of kidney function. Albuminuria was quantitated by urine albumin to creatinine ratio (UACR).

RESULTS

Plasma levels of IL-1β, IL-1RA, IL-6, TNF-α, hs-CRP, and fibrinogen were higher among participants with lower levels of eGFR. Inflammation score was higher among those with lower eGFR and higher UACR. In regression analysis adjusted for multiple covariates, eGFR, cystatin C, and UACR were strongly associated with fibrinogen, serum albumin, IL-6, and TNF-α. Each unit increase in eGFR, cystatin C, and UACR was associated with a -1.2% (95% confidence interval, -1.4, -1), 64.9% (56.8, 73.3) and 0.6% (0.4, 0.8) change in IL-6, respectively (P<0.001).

CONCLUSIONS

Biomarkers of inflammation were inversely associated with measures of kidney function and positively with albuminuria.