Disturbances of acquired immunity in hemodialysis patients

A comparison of herpes zoster incidence across the spectrum of chronic kidney disease, dialysis and transplantation

BACKGROUND

The effect of different renal replacement therapies on the risk of developing herpes zoster in renal failure patients is unknown. We aimed to investigate the incidence of herpes zoster attack among renal failure patients who were receiving different dialysis modalities, renal transplantation (RT), or not receiving any of the above mentioned therapies yet.

METHODS

A retrospective cohort study of the national health insurance register database was conducted. This observational cohort study involved 79,581 study controls, 15,802 chronic kidney disease patients, 3,694 hemodialysis (HD) patients, 317 peritoneal dialysis (PD) patients, and 159 RT patients.

RESULTS

The RT group had the worst risk of herpes zoster (hazard ratio, HR, 8.46; 95% CI 5.85-12.2), followed by PD (HR 3.61; 95% CI 2.49-4.83) and HD (HR 1.35; 95% CI 1.18-1.55), compared with the comparison group (p < 0.0001). The RT group had also the highest risk of developing herpes zoster with complications among all groups (adjusted HR 15.3). The HRs of the PD group were higher than the HRs of the HD group in terms of herpes zoster or its complications (p < 0.0001 and p = 0.0002, respectively).

CONCLUSIONS

This study suggests that different treatment modalities are associated with different risks of herpes zoster attacks in renal failure patients. PD patients had higher risks than the HD group in terms of herpes zoster or its complications.

Differences in bio-incompatibility among four biocompatible dialyzer membranes using in maintenance hemodialysis patients

BACKGROUND

Following the introduction of modified cellulosic and then synthetic membrane dialyzers, it was realized that the dialyzer bio-incompatibility depends on the membrane composition. We designed a prospective, randomized, cohort study of 6 months to determine several parameters of biocompatibility in maintenance hemodialysis (MHD) patients treated with four different membrane dialyzers.

METHODS

There were 60 MHD patients enrolled in the study. In baseline, synthetic low-flux dialyzer, polysulfone (PS) membrane was used in all patients for at least 3 months. Then the patients were randomly divided into three groups according to different dialyzer membranes. Synthetic high-flux dialyzer group, polyethersulfone membrane, cellulose triacetate (CTA) high-flux membrane, and synthetic low-flux dialyzer, polymethylmethacrylate (PMMA) membrane were used in 6 months. A new dialyzer was used for each study treatment, and there was no dialyzer reuse. The biocompatibility markers and solutes removal markers were detected repeatedly at different time points.

RESULTS

The blood levels of highly sensitive C reactive protein, interleukin (IL)-1β, and interleukin (IL)-13 showed no difference among different groups at al time points. However, the blood complement levels and white blood cell counts were significantly different among three groups. When the dialyzers changed from PS to PMMA membrane, C3a levels and white blood cell counts changed significantly (p < 0.05). Moreover, the changes of C5a levels were significantly different between group CTA and group PMMA in month 3 (p < 0.05).

CONCLUSION

There were much more differences on bio-incompatibility among different dialyzer membranes.

Vitamin D deficiency is associated with poor response to active hepatitis B immunisation in patients with chronic kidney disease

Vitamin D deficiency is highly prevalent in patients suffering from chronic kidney disease. At present it is not known whether this condition is associated with poor response to hepatitis B vaccination in these patients. We performed a retrospective analysis of 200 patients with chronic kidney disease stages 3-5D, who had undergone hepatitis B vaccination with three 40 μg recombinant hepatitis B vaccine doses in a single centre. Anti-HBs antibody titres and 25-hydroxyvitamin D (25(OH)D) levels were measured by chemiluminescence immunoassays. Vitamin D deficiency with serum levels <10 ng/mL was found in 35.5% of patients. These patients had a lower seroconversion rate than did patients with levels ≥10 ng/mL (45% vs 64%; P=0.011) and their median (25th, 75th percentile) anti-HBs antibody titres were lower (0 (0, 117)IU/L vs 48 (0, 236.5)IU/L). Non-responders had lower 25(OH)D concentrations than did responders (12.9±6.5 ng/mL vs 15.1±7.4 ng/mL; P=0.034). Treatment with a vitamin D receptor activator had no influence on the immune response. In a multiple logistic regression analysis vitamin D deficiency (OR 0.480; P=0.023) and diabetes (OR 0.496; P=0.038) remained independent and significant negative predictors of seroconversion. In conclusion, in patients with chronic kidney disease vitamin D deficiency is associated with a poor antibody formation upon hepatitis B vaccination.

Chronic kidney disease worsens sepsis and sepsis-induced acute kidney injury by releasing High Mobility Group Box Protein-1

We have shown that folate-induced kidney dysfunction and interstitial fibrosis predisposes mice to sepsis mortality. Agents that increase survival in normal septic mice were ineffective in a two-stage kidney disease model. Here we used the 5/6 nephrectomy mouse model of progressive chronic kidney disease (CKD) to study how CKD affects acute kidney injury (AKI) induced by sepsis. We induced sepsis using cecal ligation and puncture and found that the presence of CKD intensified the severity of kidney and liver injury, cytokine release, and splenic apoptosis. Accumulation of High Mobility Group Box Protein-1 (HMGB1; a late proinflammatory cytokine released from apoptotic cells), vascular endothelial growth factor (VEGF), tumor necrosis factor (TNF)-α, interleukin (IL)-6, or IL-10 was increased in CKD or sepsis alone and to a greater extent in CKD-sepsis. Only part of the increase was explained by decreased renal clearance. Surprisingly, we found splenic apoptosis in CKD, even in the absence of sepsis. Although VEGF neutralization with soluble fms-like tyrosine kinase 1 (sFLT-1) (a soluble VEGF receptor) effectively treated sepsis, it was ineffective against CKD-sepsis. A single dose of HMGB1-neutralizing antiserum administered 6 h after sepsis alone was ineffective; however, CKD-sepsis was attenuated by anti-HMGB1. Splenectomy transiently decreased circulating HMGB1 levels, reversing the effectiveness of anti-HMGB1 treatment on CKD-sepsis. Thus, progressive CKD increases the severity of sepsis, in part, by reducing the renal clearance of several cytokines. CKD-induced splenic apoptosis and HMGB1 release could be important common mediators for both CKD and sepsis.

Plasma indoleamine 2,3-dioxygenase concentration is increased in hemodialysis patients and may contribute to the pathogenesis of coronary heart disease

INTRODUCTION

Coronary heart disease (CHD) is the leading cause of death in hemodialysis (HD) patients. Inflammation contributes to the pathogenesis of atherosclerosis in this population. Indoleamine 2,3-dioxygenase (IDO), an enzyme with immunomodulatory properties, was evaluated in HD patients with or without CHD.

METHODS

Of the total of 66 HD patients, 22 of them with CHD were confirmed by coronary angiography and 24 healthy volunteers were enrolled in the study. Plasma IDO was assessed by means of enzyme-linked immunosorbent assay. Serum interleukin-6 (IL-6) and C-reactive protein (CRP) were also measured.

RESULTS

Compared with healthy volunteers, plasma IDO concentration was markedly increased in HD patients (median 8.04 ng/mL vs. 48.9 ng/mL). Serum IL-6 and CRP were also significantly increased in HD patients. Compared with HD patients without CHD, plasma IDO concentration was significantly increased in HD patients with CHD (median 38.6 ng/mL vs. 74.5 ng/mL). Neither IL-6 nor CRP differed between the last two groups. IDO was negatively correlated with IL-6 and CRP.

CONCLUSION

IDO concentration is increased in HD patients and is increased further in HD patients with CHD. It remains to be elucidated if increased IDO plays a direct role in the pathogenesis of atherosclerosis or if it affects atherosclerosis indirectly by curtailing chronic inflammation or both.

Seropositivity for anti-HCV core antigen is independently associated with increased all-cause, cardiovascular, and liver disease-related mortality in hemodialysis patients

Background

It is not known whether chronic or past hepatitis C virus (HCV) infection contributes to the high mortality rate in hemodialysis patients.

Methods

This prospective study of 1077 adult hemodialysis patients without hepatitis B virus infection used Poisson regression analysis to estimate crude and sex- and age-adjusted rates (per 1000 patient-years) of all-cause, cardiovascular, infectious disease-related and liver disease-related mortality in patients negative for HCV antibody (group A), patients positive for HCV antibody and negative for anti-HCV core antigen (group B), and patients positive for anti-HCV core antigen (group C). The relative risks (RRs) for each cause of death in group B vs group C as compared with those in group A were also estimated by Poisson regression analysis after multivariate adjustment.

Results

A total of 407 patients died during the 5-year observation period. The sex- and age-adjusted mortality rate was 71.9 in group A, 80.4 in group B, and 156 in group C. The RRs (95% CI) for death in group B vs group C were 1.23 (0.72 to 2.12) vs 1.60 (1.13 to 2.28) for all-cause death, 0.75 (0.28 to 2.02) vs 1.64 (0.98 to 2.73) for cardiovascular death, 1.64 (0.65 to 4.15) vs 1.58 (0.81 to 3.07) for infectious disease-related death, and 15.3 (1.26 to 186) vs 28.8 (3.75 to 221) for liver disease-related death, respectively.

Conclusions

Anti-HCV core antigen seropositivity independently contributes to elevated risks of all-cause and cause-specific death. Chronic HCV infection, but not past HCV infection, is a risk for death among hemodialysis patients.

Wasting and sudden cardiac death in hemodialysis patients: a post hoc analysis of 4D (Die Deutsche Diabetes Dialyse Studie)

BACKGROUND

Wasting is common in hemodialysis patients and often is accompanied by cardiovascular disease and inflammation. The cardiovascular risk profile meaningfully changes with the progression of kidney disease, and little is known about the impact of wasting on specific clinical outcomes. This study examined the effects of wasting on the various components of cardiovascular outcome and deaths caused by infection in hemodialysis patients.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

1,255 hemodialysis patients from 178 centers participating in Die Deutsche Diabetes Dialyse Studie (4D) in 1998-2004.

PREDICTOR

Moderate wasting was defined as body mass index, albumin, and creatinine values less than the median (26.7 kg/m(2), 3.8 g/dL, and 6.8 mg/dL, respectively) and C-reactive protein level less than the median (5 mg/L) at baseline. Severe wasting was defined as body mass index, albumin, and creatinine levels less than the median and C-reactive protein level greater than the median at baseline.

OUTCOMES & MEASUREMENTS

Risks of sudden cardiac death (SCD), myocardial infarction (MI), stroke, combined cardiovascular events, deaths due to infection, and all-cause mortality were determined using Cox regression analyses during a median of 4 years of follow-up.

RESULTS

196 patients had wasting (severe, n = 109; and moderate, n = 87). Overall, 617 patients died (160 of SCD and 128 of infectious deaths). Furthermore, 469 patients experienced a cardiovascular event, with MI and stroke occurring in 200 and 103 patients, respectively. Compared with patients without wasting (n = 1,059), patients with severe wasting had significantly increased risks of SCD (adjusted HR, 1.8; 95% CI, 1.1-3.1), all-cause mortality (adjusted HR, 1.8; 95% CI, 1.4-2.4), and deaths due to infection (adjusted HR, 2.3; 95% CI, 1.2-4.3). In contrast, MI was not affected. The increased risk of cardiovascular events (adjusted HR, 1.5; 95% CI, 1.0-2.1) was explained mainly by the effect of wasting on SCD.

LIMITATIONS

Selective patient cohort.

CONCLUSIONS

Wasting was associated strongly with SCD, but not MI, in diabetic hemodialysis patients. Nonatherosclerotic cardiac disease potentially has a major role to account for the increased cardiovascular events in patients with wasting, suggesting the need for novel treatment strategies.

IFN-α as a vaccine adjuvant: recent insights into the mechanisms and perspectives for its clinical use

The IFN-α family are pleiotropic cytokines with the longest record of clinical use. Over the last decade, new biological effects of IFN-α on immune cells, including dendritic cells, have been described, supporting the concept that these cytokines can act as effective vaccine adjuvants. Recently, an important advance in our understanding of the mechanisms of interferon adjuvant activity has been achieved. Some clinical studies have been performed to assess the adjuvant activity in individuals immunized with preventive vaccines, showing variable results depending on interferon/vaccine formulation and vaccinated subjects. In spite of many data in animal models, little information is available on the possible advantage of utilizing IFN-α as an adjuvant for cancer vaccines in humans. Further clinical trials specifically designed to explore vaccine adjuvant activity are needed in order to define the best conditions for using IFN-α or IFN-α-conditioned dendritic cells for the development of therapeutic vaccines.

Preventing catheter-related infections in children undergoing hemodialysis

The increased use of tunneled cuffed catheters in children on chronic hemodialysis is the result of their relative ease of insertion, pain-free dialysis and immediate use. The disadvantage of their use is that they are associated with catheter-related bacteremia (CRB), which in turn is related with increased morbidity, access loss and occasionally metastatic infections and even death. A CRB might be difficult to diagnose and is often associated with a previous history of CRB, exit-site infection, low serum albumin and long duration of catheter use. There is evidence that the use of arteriovenous fistulae is associated with lower infection rates. The implementation of effective strategies for the prevention of CRBs include the adoption of policies for improving arteriovenous fistula rates, appropriate surgical catheter insertion and optimal nursing care of the exit site, and a safe connection technique. Recently, the effectiveness of antimicrobial catheter solutions for preventing CRB has been documented in a number of randomized clinical trials. In addition, the application of antibiotic ointments at the exit sites of tunneled cuffed catheters might be significant for the reduction of Staphylococcus-related CRB. The upside is that education-based programs combining specific preventive measures can significantly reduce CRBs.

Protein-energy wasting and mortality in chronic kidney disease

Protein-energy wasting (PEW) is common in patients with chronic kidney disease (CKD) and is associated with an increased death risk from cardiovascular diseases. However, while even minor renal dysfunction is an independent predictor of adverse cardiovascular prognosis, PEW becomes clinically manifest at an advanced stage, early before or during the dialytic stage. Mechanisms causing loss of muscle protein and fat are complex and not always associated with anorexia, but are linked to several abnormalities that stimulate protein degradation and/or decrease protein synthesis. In addition, data from experimental CKD indicate that uremia specifically blunts the regenerative potential in skeletal muscle, by acting on muscle stem cells. In this discussion recent findings regarding the mechanisms responsible for malnutrition and the increase in cardiovascular risk in CKD patients are discussed. During the course of CKD, the loss of kidney excretory and metabolic functions proceed together with the activation of pathways of endothelial damage, inflammation, acidosis, alterations in insulin signaling and anorexia which are likely to orchestrate net protein catabolism and the PEW syndrome.

Impact of seropositivity to Chlamydia pneumoniae and anti-hHSP60 on cardiovascular events in hemodialysis patients

Autoimmunity to heat shock protein 60 (HSP60) has been related to atherosclerosis. Chlamydia pneumoniae (CP), the most studied infectious agent implicated in promoting atherosclerosis, produces a form of HSP60, which can induce an autoimmune response, due to high antigenic homology with human HSP60 (hHSP60). In this study, we evaluated the correlations among anti-hHSP60 antibodies, CP infection, and cardiovascular disease (CVD) in a high-risk population, such as patients undergoing hemodialysis (HD). Thirty-two patients (67.9 ± 13.9 years; male/female, 23:9) on regular HD were enrolled. Global absolute cardiovascular risk (GCR) was assessed using the Italian CUORE Project's risk charts, which evaluate age, gender, smoking habits, diabetes, systolic blood pressure, and serum cholesterol. The occurrence of cardiovascular events during a 24-month follow-up was recorded. Seropositivity to CP and the presence of anti-hHSP60 antibodies were tested by specific enzyme-linked immunosorbent assays. Inflammation was assessed by measurement of C-reactive protein (CRP) serum levels. Fifteen healthy sex and age-matched (61.9 ± 9.5 years; male/female, 11:4) subjects were the control group. Fifteen of 32 patients resulted seropositive for CP. CP + patients were older than CP-, while they did not differ for GCR, CRP, and dialytic parameters. CVD incidence was significantly higher in CP+ (9 CP+ vs 2 CP-, p < 0.05). Cox analysis recognized that the incidence of CVD was independently correlated with seropositivity to CP (HR, 7.59; p = 0.01; 95% CI = 1.63-35.4). On the other hand, there were no significant differences in anti-hHSP60 levels among CP+, CP- and healthy subjects: 18.11 μg/mL (14.8-47.8), 31.4 μg/mL (23.2-75.3), and 24.72 μg/mL (17.7-41.1), respectively. Anti-hHSP60 did not correlate to GCR, CRP, and incidence of CVD. In conclusion, our data suggest that anti-hHSP60 autoimmune response is not related to CP infection and CP-related CVD risk in HD patients.

Immunogenicity and safety of an investigational AS02(v)-adjuvanted hepatitis B vaccine in patients with renal insufficiency who failed to respond or to maintain antibody levels after prior vaccination: results of two open, randomized, comparative trials

An investigational AS02(v)-adjuvanted hepatitis B (HB-AS02) was compared with a licensed conventional recombinant hepatitis B vaccine (HBVAXPRO™; Sanofi Pasteur MSD, Lyon, France) in pre-dialysis, peritoneal dialysis and hemodialysis patients aged ≥18 years who had failed either to respond to prior vaccination with a conventional hepatitis B vaccine (Study A; n=251) or to maintain protective antibody concentrations after prior hepatitis B vaccination (Study B; n=181). These were open, randomized, comparative trials. Mean (range) age was 65.9 (31-92) and 64.6 (29-92) years in the two studies, respectively. In Study A, two doses of HB-AS02 given one month apart were found to be superior to two doses of the licensed vaccine in terms of seroprotection rate (76.9% versus 37.6%) and anti-HBs geometric mean antibody concentration (GMC; 139.3 versus 6.9mIU/ml), with antibody concentrations ≥100mIU/ml in 61.1% and 15.4% of subjects in the two groups, respectively. In Study B, one month after administration of a single booster dose, seroprotection rates were 89.0% in the HB-AS02 group and 90.8% in the licensed vaccine group, 81.3% and 60.9% of subjects had antibody concentrations ≥100mIU/ml, and anti-HBs GMCs were 1726.8 and 189.5mIU/ml. HB-AS02 was found to be more reactogenic than the licensed vaccine. In summary, the investigational HB-AS02 vaccine induced higher seroprotection rates and anti-HBs GMCs than a licensed conventional hepatitis B vaccine in uremic patients who had failed to respond or to maintain protective antibody titers after prior hepatitis B vaccination.

High-dose cefazolin on consecutive hemodialysis in anuric patients with Staphylococcal bacteremia

Methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia is a leading cause of infection in hemodialysis (HD) patients. Cloxacillin, cefazolin, and vancomycin are the mainstay antimicrobials. Cloxacillin administration leads to frequent drug dosing, longer length of stay (LOS), and higher cost, while resistance and poorer outcomes are associated with vancomycin use. Dosing cefazolin during HD allows for prolonged blood therapeutic levels. We assessed the outcomes and safety of a strategy of treating MSSA bacteremia with 2-3 g cefazolin on HD only. All HD patients with MSSA bacteremia admitted in June-December 2009 at our center and receiving this regime were compared with historical controls who received cloxacillin. Demographic characteristics and outcome measures like mortality, LOS, cost, recrudescence, and adverse drug reactions were assessed. Of 27 consecutive episodes reviewed, 14 and 13 patients received cefazolin and cloxacillin, respectively. Baseline demographics were comparable between the 2 treatment groups. More than one-third of the bacteremia was related to tunneled catheter infection. The 30-day mortality of cloxacillin- and cefazolin-treated patients was 15% and 7%, respectively (P=0.14). Two of the 11 survivors treated with cloxacillin (18%) had recrudescent bacteremia while none was observed in cefazolin-treated survivors. Cefazolin was associated with shorter LOS (10 vs. 20 days, P<0.05) and lower cost (US$8262.00 vs. US$15,367.00, P<0.05). Cefazolin use resulted in 3 idiosyncratic adverse drug reactions. Cefazolin dosed on each HD in MSSA bacteremia leads to earlier discharge and less cost. Larger prospective studies are, however, warranted to fully assess its safety and efficacy.

Effects of parathyroid hormone on immune function

Parathyroid hormone (PTH) function as immunologic mediator has become interesting with the recent usage of PTH analogue (teriparatide) in the management of osteoporosis. Since the early 1980s, PTH receptors were found on most immunologic cells (neutrophils, B and T cells). The in vitro evaluations for a possible role of PTH as immunomodulator have shown inconsistent results mainly due to methodological heterogeneity of these studies: it used different PTH formulations (rat, bovine, and human), at different dosages and different incubating periods. In some of these studies, the lymphocytes were collected from uremic patients or animals, which renders the interpretation of the results problematic due to the effect of uremic toxins. Parathyroidectomy has been found to reverse the immunologic defect in patients with high PTH levels. Nonetheless, the clinical significance of these findings is unclear. Further studies are needed to define if PTH does have immunomodulatory effects.

High prevalence of latent tuberculosis infection in dialysis patients using the interferon-gamma release assay and tuberculin skin test

BACKGROUND AND OBJECTIVES

Patients in ESRD on hemodialysis with latent tuberculosis (TB) infection have 10 to 25 times the risk of reactivation into active disease compared with healthy adults. This study investigates the prevalence of latent TB infection in dialysis patients from a country with an intermediate burden of TB and its associated risk factors using the QuantiFERON-TB Gold in-tube test (QGIT) and the tuberculin skin test (TST).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a prospective, cross-sectional study performed at a medical center in Taiwan on dialysis patients. Each patient underwent QGIT, two-step TST using 2 tuberculin units (TU) of PPD RT-23, a chest x-ray to exclude active TB, and an interview to determine TB risk factors.

RESULTS

Ninety-three of 190 eligible patients were enrolled: 35 men and 58 women. 64.8% were vaccinated with the Bacille-Calmette-Guérin (BCG) vaccination. Overall, 34.4% were positive by QGIT and 10.8% were indeterminate. Using a 10-mm TST cutoff, 53.9% were positive. There was poor correlation between TST and QGIT at any TST cutoff criteria. There was a significant increasing trend of QGIT positivity with age in those younger than 70 years, and, conversely, a decreasing trend of TST reactivity with age. Significant risk factors for QGIT positivity included age and past TB disease.

CONCLUSIONS

This study shows a high prevalence of latent TB infection in dialysis patients in a country with an intermediate burden of TB. QGIT in dialysis patients correlated better than TST with the risk of TB infection and past TB disease.

PREFABL: predictors of failure of antibiotic locks for the treatment of catheter-related bacteraemia

BACKGROUND

Antibiotic lock (ABL) solutions can effectively treat catheter-related bacteraemia (CRB) without the need for catheter exchange. This approach does not increase secondary infectious complications. We evaluated the risk factors that contribute to failure when CRB is treated with ABLs and systemic antibiotics in paediatric haemodialysis patients.

METHODS

A retrospective chart review of 72 children on haemodialysis between January 2004 and June 2006 was performed. We evaluated risk factors for ABL treatment using patients' characteristics, CRB/catheter characteristics and patients' biochemical profiles. The first CRB of each catheter was included in the statistical analysis. Our end points were outcome at 2 weeks of treatment and at 6 weeks following treatment. Compound symmetry covariance structure was employed for statistical analysis.

RESULTS

We treated 149 CRB in 50 patients. The incidence was 3.4 CRB/1000 catheter days. Thirty CRB failed to be cleared with the use of ABL and systemic antibiotics at 2 weeks of treatment (30/149, 20 vs 80%, P < 0.001). Twenty-four of these catheters required exchange. Thirty-nine of the treated catheters got re-infected within the next 6 weeks (39/125, 31 vs 69%, P < 0.001). CRB aetiology was the only statistically significant independent variable for 2-week outcome (P = 0.033). Coagulase-negative Staphylococcus CRB had higher odds of being cleared at 2 weeks compared with other CRB aetiologies. For the 6-week outcome, the statistically significant independent variables in the final model included age (P = 0.048) and serum phosphorous level (P < 0.001). Younger age and higher serum phosphorous levels were independent risk factors for failure at 6 weeks with re-infection. Area under the receiver operating characteristic (ROC) curve for the model of the 2-week outcome was 0.736 with the percentage of correct predictions at 81.2%. Area under the ROC curve for the model of the 6-week outcome was 0.689 with the percentage of correct predictions at 75.5%.

CONCLUSIONS

CRB can effectively be treated with ABLs and systemic antibiotics. CRB aetiology is the only independent variable of early treatment failure. Younger age and higher serum phosphorous levels are independent risk factors for re-infection at 6 weeks.

Potential role of the soluble form of CD40 in deficient immunological function of dialysis patients: new findings of its amelioration using polymethylmethacrylate (PMMA) membrane

Even though numerous studies have helped to better delineate abnormalities of either innate or adaptive immune system in end-stage renal disease (ESRD) patients, understanding immune dysfunctions in ESRD patients remains a very complex puzzle with missing pieces. In this context, we showed that the soluble form of CD40 (sCD40) is elevated in ESRD patients and is associated with a lack of response to hepatitis B vaccination. Interestingly, although most dialysis membranes are unable to clear sCD40, we demonstrated that polymethylmethacrylate (PMMA) BK-F membranes (Toray Medical Company, Japan) allow a dramatic diminution of the molecule. We took advantage of this observation to address the question of the potential usefulness of PMMA membrane (BK-F series) in the improvement of humoral immune response of ESRD patients. We, thus, present our recent data highlighting the potential role of BK-F membrane in the improvement of hepatitis B vaccination of ESRD patients who failed to mount a protective immune response despite one or more well-conducted anterior vaccination.

Taken as a whole, our findings reinforced the concept of seeing dialysis membranes not just as a simple diffusive device but as a tool to tailor dialysis procedure to improve the global quality of life of ESRD patients. This opens a wide area of investigation, notably for the management of immunological dysfunction of ESRD patients.

Paricalcitol reduces basal and lipopolysaccharide-induced (LPS) TNF-alpha and IL-8 production by human peripheral blood mononuclear cells

INTRODUCTION

Vitamin D and its analogues proved to exert immunomodulatory effects. Paricalcitol is a vitamin D analogue that is safe. It has been used for years in the treatment of secondary hyperparathyroidism in hemodialysis patients and, importantly, it is less calcemic than vitamin D. In this study the immunomodulatory/anti-inflammatory properties of paricalcitol were evaluated in vitro.

SUBJECT AND METHODS

Ten healthy volunteers enrolled into the study. Peripheral blood mononuclear cells (PBMC) at a concentration of 10(6) cells per well were cultured for 48 h in the presence or not of lipopolysaccharide (LPS) (100 ng/ml) and in the presence or not of paricalcitol (10(-8) M). TNF-alpha and IL-8 were measured in the supernatants by ELISA.

RESULTS

Basal TNF-alpha concentration (50.3 +/- 22 pg/ml) was reduced by paricalcitol (44.1 +/- 23.2 pg/ml). LPS increased TNF-alpha concentration (150.0 +/- 81.7 pg/ml), but paricalcitol reduced it (121.1 +/- 69.0 pg/ml). The effect of paricalcitol on IL-8 production was more profound. Basal IL-8 concentration (1926 +/- 455 pg/ml) was reduced by paricalcitol (1273 +/- 472 pg/ml). LPS increased IL-8 concentration (2361 +/- 385 pg/ml), but paricalcitol returned it to its basal level (1849 +/- 417 pg/ml).

CONCLUSION

The in vitro inhibition of transforming growth factor alpha and interleukin 8 by paricalcitol confirms the immunomodulatory properties of this vitamin D analogue.

Molecular mechanisms of hepcidin regulation: implications for the anemia of CKD

Anemia is prevalent in patients with chronic kidney disease (CKD) and is associated with lower quality of life and higher risk of adverse outcomes, including cardiovascular disease and death. Anemia management in patients with CKD currently revolves around the use of erythropoiesis-stimulating agents and supplemental iron. However, many patients do not respond adequately and/or require high doses of these medications. Furthermore, recent clinical trials have shown that targeting higher hemoglobin levels with conventional therapies leads to increased cardiovascular morbidity and mortality, particularly when higher doses of erythropoiesis-stimulating agents are used and in patients who are poorly responsive to therapy. One explanation for the poor response to conventional therapies in some patients is that these treatments do not fully address the underlying cause of the anemia. In many patients with CKD, as with patients with other chronic inflammatory diseases, poor absorption of dietary iron and the inability to use the body's iron stores contribute to the anemia. Recent research suggests that these abnormalities in iron balance may be caused by increased levels of the key iron regulatory hormone hepcidin. This article reviews the pathogenesis of anemia in CKD, the role and regulation of hepcidin in systemic iron homeostasis and the anemia of CKD, and the potential diagnostic and therapeutic implications of these findings.

The general picture of uremia

The clinical presentation and manifestations of uremia that constitute the uremic syndrome are presented. The first descriptions of patients with advanced or "terminal" renal failure who were treated with hemodialysis are evoked to illustrate the wide range of signs and symptoms that are associated even to a moderate decrease in renal function, presently referred to as chronic kidney disease (CKD) stages 3-4. The kidney is a central organ guaranteeing the maintenance of the "milieu intérieur," where all the cells of the body are generated, develop, proliferate, and die. Chronic kidney disease, by altering the "milieu intérieur," may alter the metabolism of every type of cell or organ, leading to a wide scope of symptoms. The most frequently observed signs in daily clinical practice are summarized and put into the perspective of the renal physician. Disturbances of ion and water metabolism, hypertension, cardiovascular disease, anemia, mineral and bone disorders, endocrine, inmmunologic and neurologic syndromes are described. The addition of these clinical manifestations defines and describes each uremic patient as a specific individual. The pathophysiologic mechanisms by which each of these signs and symptoms appears and the particular compounds responsible for their occurrence, are described in depth in subsequent chapters of this issue.

Procalcitonin values after dialysis is closely related to type of dialysis membrane

BACKGROUND

Infections account for considerable morbidity and mortality in patients with chronic renal failure undergoing hemodialysis (HD). Diagnosis of infection in HD patients is challenging because the most used laboratory parameters may be increased even in the absence of infection. In this setting, procalcitonin (PCT) could be useful for detection of systemic bacterial infections.

METHODS

We measured high sensitivity C Reactive Protein (hsCRP) and PCT serum levels before and immediately after dialysis in 44 HD patients (22 treated with high- and 22 with low-flux membranes), without history of infections.

RESULTS

Patients on HD by high-flux membranes, but not by low-flux membranes, displayed mean PCT values significantly decreased after dialysis (high-flux: 0.50 vs. 0.26 ng/mL, p=0.005; low-flux: 0.41 vs. 0.42 ng/mL, p=0.863). HsCRP levels were unchanged. HsCRP correlated with PCT values both before and after HD only in patients on HD by low-flux membranes (r=0.51 and 0.47 before and after HD respectively; p<0.05).

CONCLUSIONS

Although PCT is considered a sensitive and specific diagnostic and prognostic marker of systemic bacterial infection, we suggest that specific reference ranges might be developed in patient with impaired renal function, also showing that and its clinical usefulness might be limited in patients undergoing HD with high-flux membranes.

Decreased CD3+CD16+ natural killer-like T-cell percentage and zeta-chain expression accompany chronic inflammation in haemodialysis patients

AIM

Clinical and experimental data indicate a deficient immune response in haemodialysis (HD) patients. Natural killer-like (NKL) T cells express on their surface both the T-cell antigen receptor (TCR) and a diverse set of NK-cell receptors (NKR) and share properties of both T cells and NK cells. zeta-Chain phosphorylation is an early event that follows TCR activation or some NKR activation. The zeta-chain of both T cell and NK cells is downregulated in many chronic inflammatory states, HD included. In the present study, NKL T-cell percentage and zeta-chain expression in HD patients were evaluated.

METHODS

Thirty-three stable HD patients and 30 healthy volunteers were enrolled into the study. NKL T-cell percentage and NKL T-cell zeta-chain mean fluorescence intensity (MFI) were evaluated with flow cytometry. The inflammatory markers C-reactive protein, interleukin-6 and tumour necrosis factor-alpha were measured in the serum by means of enzyme-linked immunosorbent assay.

RESULTS

All the evaluated markers of inflammation were increased in HD patients. In these patients, NKL T-cell percentage (1.71 +/- 1.69% vs 3.94 +/- 3.86%) and zeta-chain MFI (3.66 +/- 2.79 vs 7.03 +/- 7.91) were decreased.

CONCLUSIONS

NKL T-cell percentage and zeta-chain expression is decreased in HD patients. Taking into consideration the continuously increasing age of the HD patients and that normally NKL T-cell numbers increase with age counteracting the impaired T-cell and NK-cell function accompanying advancing age, the above NKL T-cell disturbances could contribute to the impaired immune response in this population. Measures towards alleviating chronic inflammation could partially restore NKL T-cell impairment.

Recombinant interferon-alpha2b improves immune response to hepatitis B vaccination in haemodialysis patients: results of a randomised clinical trial

The use of adjuvants capable of improving the deficient immune response to hepatitis B virus (HBV) vaccine in haemodialysis patients is highly needed. Among potential adjuvants, type I interferons deserve a special attention in view of their known effects promoting cellular and humoral immune responses. The aim of the present trial was to evaluate the effects of recombinant interferon-alpha2b (IFN) administered as an adjuvant of HBV vaccine in unvaccinated haemodialysis patients. A significant and early enhancing effect on the antibody response was observed in patients receiving IFN. In addition, a predominance of IgG1 anti-HBs along with a transient normalization of circulating Th1 lymphocytes was only found in patients receiving IFN who achieved an early seroprotection. However, 6 months after the last vaccine dose, no significant differences were observed in the seroprotection rate achieved in patients vaccinated with IFN compared to that in patients receiving HBV vaccine alone. Mild to moderate fever, asthenia, and arthromyalgia were the most common reactions that occurred in vaccinees given IFN. In conclusion, addition of IFN to HBV vaccine, under the conditions used in this trial, is safe and achieves an earlier and higher seroprotection rate improving Th1-dependent immune response in haemodialysis patients.

Impact of hemodialysis therapy on hepatitis C virus infection: a deeper insight

Hepatitis C Virus (HCV) infection remains prevalent in patients receiving regular dialysis all over the world. The adverse impact of anti-HCV serologic status on mortality in the dialysis population has been documented. Antiviral therapy for hepatitis C in chronic kidney disease (CKD) patients, including the dialysis population, is still unsatisfactory. Several findings support a different course of HCV in dialysis patients versus the non-uremic population. The HCV viral load appears lower in hemodialysis patients with HCV despite the immune compromise caused by chronic uremia; the histologic abnormalities seem milder, and a severe clinical course of chronic hepatitis C is unusual in most hemodialysis (HD) patients. It appears that the HD procedure per se can preserve patients from an aggressive course of HCV by reducing the viral load (HCV RNA). The mechanisms by which the HD procedure lowers HCV viremia remain largely speculative: the passage of viral particles into the dialysate, the trapping of the virus on the surface of the dialyzer membrane, and an indirect host-mediated mechanism have been cited. The latter hypothesis implicates the production of interferon-alpha, hepatocyte growth factor, or other cytokines provided with antiviral activities during the hemodialysis sessions. Clinical trials aimed at clarifying this issue are under way.

Acute infection with a single hepatitis C virus strain in dialysis patients: Analysis of adaptive immune response and viral variability

BACKGROUND/AIMS

While the adaptive immune response is crucial for spontaneous resolution of acute hepatitis C virus (HCV) infection, it also constitutes the driving force for viral escape. For acutely HCV-infected dialysis patients, little is known about the host response and its impact on viral evolution.

METHODS

Four haemodialysis patients accidentally infected with the same HCV strain were prospectively investigated with respect to the clinical course, CD4+ and CD8+ T-cell responses, neutralizing antibodies, viral kinetics and sequence variability.

RESULTS

In one patient, a robust CD4+ T-cell response was associated with transient control of infection, while in the other patients, weak responses correlated with persistently high viremia. Despite the presence of CD8+ T-cell effectors in the first patient, no sequence differences were detected in targeted regions of the viral genome in any of the patients when viral persistence was established. Genetic stability in the envelope genes, including the hypervariable regions, correlated with low-level or absent neutralizing antibodies in all of the patients.

CONCLUSIONS

The establishment of viral persistence in the special patient group of dialysis patients is due to a failure of the adaptive immune system, as shown by the absence of significant T-cell and antibody responses, as well as viral variability.

Immunogenicity of a standard trivalent influenza vaccine in patients on long-term hemodialysis: an open-label trial

BACKGROUND

Disturbances in acquired immunity are considered to be responsible, at least in part, for the high infection rate and inadequate response to vaccinations observed in hemodialysis (HD) patients. The present prospective trial aimed to: (1) evaluate the immunogenicity of a standard influenza vaccine in HD patients, and (2) identify determinants of the immune response.

STUDY DESIGN

Prospective interventional open-label study.

SETTING & PARTICIPANTS

201 long-term HD patients and 41 healthy volunteers.

INTERVENTION

Vaccination with a standard trivalent inactivated influenza vaccine.

OUTCOMES

The primary outcome was seroprotection rate, defined as percentage of participants with an antibody titer of 40 or greater 1 month after vaccination.

MEASUREMENTS

All antibody titers were determined in duplicate by using the hemagglutination inhibition assay. Regression analyses were performed to investigate the association between demographics, uremic retention solutes (including p-cresol), inflammation, nutrition, iron status, trace elements, and immune response in HD patients.

RESULTS

More than 80% of HD patients showed seroprotection after vaccination. The immune response of HD patients was similar to that of healthy volunteers. Booster vaccination did not improve the immune response. High serum ferritin level was the only parameter independently associated with a better vaccination-induced antibody response in HD patients.

LIMITATIONS

A high seroprotection rate at baseline undermined the power to identify clinical determinants of the immune response.

CONCLUSIONS

Influenza vaccination is as efficacious in HD patients as in healthy volunteers. With the exception of serum ferritin, none of the investigated parameters of nutrition, inflammation, and dialysis adequacy had a significant impact on the immune response. Our data support annual vaccination of HD patients and question the clinical relevance of disturbances in acquired immunity in contemporary HD patients.

FOXP3+ regulatory T-cells in chronic kidney disease: molecular pathways and clinical implications

CD4+/FOXP3+ regulatory T-cells (Tregs) are essential for the maintenance of self-tolerance and Tregs deficiency results in spontaneous autoimmunity in both mice and humans. The forkhead box P3 (FOXP3) expression is required for both survival of Tregs precursors as well as their function. This suggests that Tregs may use multiple mechanisms to limit autoimmunity and may reflect functional heterogeneity among Tregs subsets that localize to distinct tissue environments. Both cell contact- and cytokine-based immunosuppressive mechanisms would require that Tregs be in close proximity to their targets. The fundamental regulatory activity that can be consistently demonstrated by Tregs in vivo and in vitro has stimulated great interest in developing novel strategies for treating ongoing inflammatory conditions. Patients with end-stage kidney disease (ESKD) are known to display a cellular immune dysfunction. Uremic solutes that accumulate during ESKD may be involved in these processes. In these patients, oxidative stress induced by oxLDL may increase Tregs sensitivity to Fas-mediated apoptosis in part as a consequence of 26S proteasome activation. The 26S proteasome, an ATP-dependent multisubunit protease complex found in the cytoplasm and in the nucleus of all eukaryotic cells, constitutes the central proteolytic machinery of the ubiquitin/proteasome system. Considering the effect of uremia and oxLDL, Tregs from patients with ESKD exhibit early cell-cycle arrest and become apoptotic. These phenomena are the consequence of the oxLDL inhibited proteasome proteolytic activity of p27(Kipl) and Bax proteins in Tregs. This may be one mechanistic explanation of the cellular immune dysfunction in patients with ESKD and may have important implications in clinics, since this response could contribute to the micro-inflammation and atherogenesis encountered in this population.

Obesity management in adults with CKD

A 22-year-old African-American woman who has been dialysis dependent for four months due to hypertensive kidney disease is referred for kidney transplantation evaluation. Due to the recent occlusion of her left forearm arteriovenous graft, she is currently being dialyzed via a right internal jugular tunneled catheter. Her medications include methyldopa 250 mg bid, Tums 1000 mg with each meal and erythropoietin with dialysis. The patient is single without children, unemployed and lives with her 38 year old mother. She does not smoke or drink. Her review of systems is unremarkable. On physical exam, her weight is 284 pounds, height is 5 feet 2 inches and her body mass index is 51.9 kg/m2. The blood pressure is 130/80 and the cardiac and pulmonary exams are unremarkable. The surgeon feels she is otherwise a good candidate for transplantation except she must lose weight before being listed. What advice should she be given regarding weight loss?

The Role of Hepcidin in Iron Homeostasis and Anemia in Hemodialysis Patients

Anemia is a common complication in hemodialysis (HD) patients. Despite the great success of recombinant human erythropoietin in clinical practice, resistance to this therapy is common. Additionally, nephrologists frequently witness a rapid and significant drop in their patients’ hematocrit during the course of various acute events that regularly take place in this sensitive population. Hepcidin, a recently identified peptide, may mediate this development in many instances. Hepcidin production is regulated by hypoxia/anemia, iron status, and importantly, inflammation. This peptide can block iron absorption by the duodenum, iron release from both the liver (the main iron storage pool) and, more significantly, the macrophages interrupting iron recycling between senescent red cells and the reticuloendothelial system. The decreased availability of iron for erythropoiesis leads to the anemia of chronic disease or, in HD patients, aggravate an already existing anemia HD is now widely considered an inflammatory state probably accounting for the increased serum hepcidin levels that have been associated with it. The physiology of hepcidin and its possible contribution to the pathogenesis of anemia in HD patients are the subject of this review.

New insights into uremic toxicity

PURPOSE OF REVIEW

Our concept of uremia has expanded to encompass the illness patients begin to suffer as glomerular filtration rate declines long before the onset of end-stage renal disease (ESRD) not explained by known derangements in volume status or metabolic parameters. New insights into the accumulation of uremic toxins and the loss of function of hormones and enzymes provide important information on the etiology of uremia.

RECENT FINDINGS

New data are accumulating on the identity and toxicity of uremic toxins and the syndromes that encompass uremia. rho-Cresol sulfate and indoxyl sulfate are small, protein-bound molecules that are poorly cleared with dialysis. These molecules have been linked to cardiovascular disease and oxidative injury. Impaired immunity plays a central role in the morbidity of ESRD and may be both the result of uremic toxicity and a contributor to oxidative stress in ESRD. Uremic cachexia is an underrecognized uremic syndrome. New insights into disordered feeding circuits in ESRD may lead to novel therapies using hormone agonists.

SUMMARY

Mortality in ESRD remains unacceptably high. It is hoped that as knowledge emerges on the causes and consequences of uremia, we are embarking on an era not only of new insights but also new and effective treatments for patients with the ill effects of uremia.

Aspects of immune dysfunction in end-stage renal disease

End-stage renal disease (ESRD) is associated with significantly increased morbidity and mortality resulting from cardiovascular disease (CVD) and infections, accounting for 50% and 20%, respectively, of the total mortality in ESRD patients. It is possible that these two complications are linked to alterations in the immune system in ESRD, as uremia is associated with a state of immune dysfunction characterized by immunodepression that contributes to the high prevalence of infections among these patients, as well as by immunoactivation resulting in inflammation that may contribute to CVD. This review describes disorders of the innate and adaptive immune systems in ESRD, underlining the specific role of ESRD-associated disturbances of Toll-like receptors. Finally, based on the emerging links between the alterations of immune system, CVD, and infections in ESRD patients, it emphasizes the potential role of the immune dysfunction in ESRD as an underlying cause for the high mortality in this patient population and the need for more studies in this area.

Epidemiology of acute infections among patients with chronic kidney disease

The objectives of this review were (1) to review recent literature on the rates, risk factors, and outcomes of infections in patients who had chronic kidney disease (CKD) and did or did not require renal replacement therapy; (2) to review literature on the efficacy and use of selected vaccines for patients with CKD; and (3) to outline a research framework for examining key issues regarding infections in patients with CKD. Infection-related hospitalizations contribute substantially to excess morbidity and mortality in patients with ESRD, and infection is the second leading cause of death in this population. Patients who have CKD and do not require renal replacement therapy seem to be at higher risk for infection compared with patients without CKD; however, data about patients who have CKD and do not require dialysis therapy are very limited. Numerous factors potentially predispose patients with CKD to infection: advanced age, presence of coexisting illnesses, vaccine hyporesponsiveness, immunosuppressive therapy, uremia, dialysis access, and the dialysis procedure. Targeted vaccination seems to have variable efficacy in the setting of CKD and is generally underused in this population. In conclusion, infection is a primary issue when caring for patients who receive maintenance dialysis. Very limited data exist about the rates, risk factors, and outcomes of infection in patients who have CKD and do not require dialysis. Future research is needed to delineate accurately the epidemiology of infections in these populations and to develop effective preventive strategies across the spectrum of CKD severity.

Serum phosphate levels and risk of infection in incident dialysis patients

BACKGROUND AND OBJECTIVES

Hyperphosphatemia is highly prevalent in dialysis patients and may be associated with immune dysfunction. The association of serum phosphate level with infection remains largely unexamined.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In an incident cohort of 1010 dialysis patients enrolled from 1995 to 1998 and treated in 80 US clinics, the association of phosphate level (low <3.5; normal 3.5 to 5.5; high >5.5 mg/dl) at baseline and during follow-up with the risk for incident inpatient and outpatient infection-related events was examined. Infectious events were identified from US Renal Data System data (mean follow-up 3.3 yr). Incidence rate ratios for all infections, sepsis, respiratory tract infections, and osteomyelitis were obtained using multivariable Poisson models, adjusting for potential confounders (age, race, gender, smoking, comorbidity, and laboratory values).

RESULTS

Infections of any type (n = 1398) were more frequent among patients with high phosphate levels at baseline, relative to normal; this association was not changed by adjustment for parathyroid hormone level. Similarly, high versus normal baseline phosphate was associated with increased risk for sepsis and osteomyelitis but not respiratory tract infections. Associations with calcium were generally NS, and results with calcium-phosphate product mirrored the phosphate results.

CONCLUSIONS

High phosphate levels may be associated with increased risk for infection, contributing further to the rationale for aggressive management of hyperphosphatemia in dialysis 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.