Inflammation is an important predictor of increased cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD), but the mechanisms behind the chronic activation of the immune system are not clearly understood. CKD patients develop fluid overload, which has been proposed to be a stimulus for inflammatory activation due to the translocation of macromolecules from the gut. We hypothesize that fluid overload is associated with signs of systemic inflammation and endotoxaemia in stages 1-5 CKD patients. The aim of this prospective study was to evaluate the associations between renal function, fluid status [evaluated by the inferior vena cava diameter (IVCD) and the collapsibility index (CI)], systemic inflammation [plasma levels of C-reactive protein (CRP), fibrinogen and albumin] and endotoxaemia (through the Limulus amebocyte lysate enzymatic assay) in a group of CKD patients in our out-patient clinic. The population consisted of 74 (mean of 57; range 23-83 years of age; 47% males) CKD patients with glomerular filtration rate (based on the mean of urea and creatinine clearances) of 34 ml/min. Both albumin (Rho = 0.25; P = 0.05) and fibrinogen (Rho= - 0.48; P < 0.0001) were significantly correlated to glomerular filtration rate (GFR). According to the IVCD, 84% of the patients were fluid overloaded, while 83% were considered overloaded by the CI. Signs of endotoxaemia were detected in all patients. Endotoxin levels were higher in patients with signs of fluid overload (0.85 +/- 0.11ng/l) when compared with patients with normal values of IVCD (0.61 +/- 0.05 ng/l; P < 0.05). Endotoxin levels correlated to both IVCD (Rho=0.33, P < 0.005) and CI (Rho = -0.25, P < 0.05). There was no correlation between endotoxin levels and GFR, CRP or fibrinogen. In summary, although most CKD patients presented signs of fluid overload that was associated with endotoxaemia, there was no association between endotoxaemia and systemic inflammation, suggesting the endotoxaemia may not be the main determinant of the inflammatory status in this group of patients.

Chemokines and adhesion molecules are involved in early events of atherogenesis. In the present study, we investigated the effects of the uremic milieu on the expression of monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8), soluble vascular adhesion molecule-1 (sVCAM-1) and soluble intercellular adhesion molecule-1 (sICAM-1) and their relationship to cardiovascular status. Plasma samples were obtained from patients in different stages of chronic kidney disease (CKD). Cardiovascular status was evaluated by intima-media thickness and endothelial dysfunction by flow mediation dilatation and proteinuria. In vitro studies were performed using human umbilical endothelial cells exposed to uremic plasma or plasma from healthy subjects. MCP-1, IL-8, sVCAM-1 and sICAM-1 levels in plasma and in supernatant were analyzed by enzyme-linked immunosorbent assay. The population consisted of 73 (mean age 57 years; 48% males) CKD patients with glomerular filtration rate (GFR) of 37 ± 2 ml/min. MCP-1 and sVCAM-1 plasma levels were negatively correlated with GFR (ρ = –0.40, p < 0.0005 and ρ = –0.42, p < 0.0005, respectively). Fibrinogen was positively correlated with MCP-1, sICAM-1 and sVCAM-1 (ρ = 0.33, p < 0.005, ρ = 0.32, p < 0.05 and ρ = 0.25, p < 0.05, respectively) and ultra-high-sensitivity C-reactive protein was positively correlated with sICAM-1 (ρ = 0.25, p < 0.0005). Plasma IL-8 had a significant positive correlation with proteinuria (ρ = 0.31, p < 0.01). There was a time- and CKD-stage-dependent MCP-1, IL-8 and sVCAM-1 endothelial expression (p < 0.05). In summary, plasma levels of markers of endothelial cell activation (MCP-1 and sVCAM-1) are increased in more advanced CKD. Exposure of endothelial cells to uremic plasma results in a time- and CKD-stage-dependent increased expression of MCP-1, IL-8 and sVCAM-1, suggesting a link between vascular activation, systemic inflammation and uremic toxicity. Future studies are necessary to investigate whether these biomarkers add predictive value in comparison to the previously described ones. Also, endothelial response to uremic toxicity should be viewed as a potential target for intervention in order to reduce morbidity and mortality in CKD-related cardiovascular disease.

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Chronic inflammation is closely linked to several complications of chronic kidney disease (CKD), such as vascular calcification, accelerated atherosclerosis, loss of appetite, insulin resistance, increased muscle catabolism and anemia. As a consequence, inflammation is a predictor of mortality in this group of patients. Specific causes of the activation of the immune system in CKD are largely unknown. Endotoxin (ET) release to the circulation represents a potentially important target for interventions aiming to reduce mortality in CKD patients. In this minireview, we propose that there are several potential sources of endotoxemia in CKD and that gut translocation, leading to the generation of ligands of the innate immune response, represents a potentially reversible cause. Prevention of endotoxemia, through treating foci of ET (periodontal disease, catheters, vascular access) or reducing translocation from the gut, will potentially reduce the inflammatory response.

Background: Chronic kidney disease (CKD) is characterized by progressive kidney dysfunction accompanied by accumulation of uremic toxins and a potential disequilibrium between the redox status and the generation of prooxidants, resulting in oxidative stress and chronic inflammation which is associated with complications (particularly cardiovascular disease) in this population. We aimed to analyze the concentration of total plasma thiols (indicator of antioxidant capacity) and the protein carbonyl content (a marker of carbonyl stress) in relation to kidney function and inflammation in a group of patients with CKD. Patients and Methods: A group of 68 patients with CKD (stages 2–5; mean age 57 ± 12 years, 46% male, 34% diabetics) and another group of 21 patients who underwent living donor kidney transplantation (mean age 36 ± 17 years, 50% male, 10% diabetics, and 9 ± 2 months after renal transplantation) were included in the study. Total plasma thiol and protein carbonyl levels were determined by the DTNB and DNPH methods, respectively, and were adjusted to the plasma albumin concentrations. Plasma levels of fibrinogen and C-reactive protein (CRP) were measured by routine methods and used as markers of inflammation. Results: Mean glomerular filtration rate (GFR) was 48 ml/min, and there was a positive correlation between GFR and thiol (r = 0.25, p < 0.05) and a negative correlation between GFR and carbonyl (r = –0.26, p < 0.05), fibrinogen (r = –0.45, p < 0.0001) and CRP (r = –0.14, p = ns). Carbonyl strongly correlated with CRP (0.49, p < 0.0001) and fibrinogen (0.30, p < 0.01). There was a significant reduction in plasma carbonyl after renal transplantation (1.4 ± 0.4 nmol/mg albumin), compared with the levels before the procedure (2.0 ± 1.4 nmol/mg albumin, p < 0.05), which parallels an improvement in thiol levels (15 ± 4 vs. 21 ± 5 nmol/mg albumin, p < 0.001). In addition, there was a significant correlation between CRP and carbonyl after the transplantation (r = 0.65; p < 0.005). Conclusion: We observed that patients with CKD present an altered redox status and increased signs of carbonyl stress and inflammatory activity as kidney function deteriorates, which was partially but significantly improved after renal transplantation. These findings indicate the importance of renal function in the complications of CKD related to oxidative stress and inflammation.

Introduction: Uremic toxins play a pivotal role in the development of systemic complications of chronic kidney disease (CKD), which are largely mediated by the activation of the immune system. Triggers of inflammation in CKD are largely unknown and strategies aiming to reduce circulating ligands that could start the inflammatory response are potentially important. In the present study, we investigated the impact of sevelamer hydrochloride treatment in reducing endotoxemia and inflammation in a group of hemodialysis (HD) patients. Material and Methods: HD patients, who were converted from calcium carbonate treatment to sevelamer according to KDOQI guidelines, were included and prospectively followed for 6 months. Systemic inflammation was evaluated by serum ultra-high-sensitivity C-reactive protein (hsCRP) using an automated immunoturbidimetric assay. Endotoxin was measured using Limulus amebocyte lysate chromogenic endpoint assay. All the analyses were performed immediately before conversion and after 6 months of treatment. Results: After the exclusion of patients discontinuing the treatment, 20 patients (mean dialysis time 12 ± 4 months on HD, age 52 ± 2 years, 38% males, 11% diabetics) were included in the analysis. No significant changes were observed in Ca, P and PTH levels, while a reduction in cholesterol levels was seen. Plasma concentration of hsCRP and endotoxin significantly decreased after 6 months of conversion to sevelamer compared with baseline. Conclusion: We conclude that sevelamer treatment leads to a decrease in hsCRP levels, which was accompanied by a parallel decrease in endotoxemia, suggesting that endotoxemia may contribute to the systemic inflammation in HD patients, which was partially reduced by the use of sevelamer.

During the past few years, it has become increasingly evident that residual renal function (RRF) is an important and independent predictor of poor outcome in patients with chronic kidney disease (CKD). Although the causes of this observation are not fully understood, it appears that the loss of RRF impairs both fluid removal and clearance of solutes, which in turn leads to uremic toxicity and increased morbidity and mortality. There is increasing evidence that patients with CKD develop signs of fluid overload already in the early phases of the disease, and this may be a stimulus for inflammatory activation. Recently, an inflammatory component was identified in uremic atherosclerotic and non-atherosclerotic cardiovascular disease (CVD), which have been consistently associated with poor clinical outcome in patients with CKD. Signs of systemic inflammation occur in parallel to the impairment in renal function, and the pathophysiology is most likely multifactorial, including a decrease in cytokine clearance, advanced glycation end-product accumulation, oxidative stress, and principal fluid overload. Additionally, inflammation seems to be a predictor of accelerated loss of renal function. In this article, we discuss the evidence showing that patients with CKD generally have fluid overload, the mechanisms by which impaired renal function may lead to a chronic inflammatory state, and the available information linking fluid overload to accelerated loss of renal function and CVD through inflammation. Inflammation may lead to the development of complications of CKD, in particular CVD, but on the other hand may also lead to a faster progression of renal disease. Strategies aiming to reduce fluid overload may be useful to reduce cardiovascular morbidity and mortality, but also preserve RRF.

Background: Renal failure is associated with activation of inflammatory response, but the mechanisms behind this observation and potential anti-inflammatory strategies are yet to be defined. Endotoxin (ET) translocation from the intestinal lumen can potentially trigger systemic inflammatory response, and ET binding represents a potential anti-inflammatory strategy in renal failure. The aim of this study was to evaluate the ET-binding capacity of sevelamer carbonate in an animal model of renal failure. Material and Methods: Rats were 5/6 nephrectomized to induce uremia (U) and sham-operated rats were allocated to receive normal chow (controls) or a diet with 3% sevelamer carbonate added (+SC) for 60 days. Tumor necrosis factor-α (TNF-α) and ET were measured in plasma on days 7, 30 and 60 in all animals. Results: Renal failure induced an inflammatory response, since TNF-α levels were undetectable in all control animals in contrast to the uremic group (3.18 ± 0.62, 2.58 ± 0.54 and 1.86 ± 0.47 pg/ml, respectively, on days 7, 30 and 60; p < 0.05 at all time points). Similarly, uremic rats presented an increase in ET levels (0.038 ± 0.007 EU/ml) when compared to sham-operated animals (0.008 ± 0.006 EU/ml; p < 0.05). During the study, TNF-α levels in U + SC rats were significantly lower compared with U-control animals (p < 0.05). Similarly, ET levels in U + SC rats were lower when compared with U-control rats (p < 0.005). Conclusion: In conclusion, induction of renal failure triggered inflammation and induced endotoxemia in this experimental model of chronic kidney disease, which were reduced by sevelamer treatment. This data suggests that sevelamer carbonate induces an anti-inflammatory effect in parallel to a reduction in ET.