Effect of hemodialysis on leukocyte adhesion receptor expression

Polymorphonuclear phenotypical expression of CD18, at baseline and after in vitro activation, in several clinical disorders: Revision of our case series

BACKGROUND

In relation to the different and important roles of the beta2 integrins, we have revisited the expression of polymorphonuclear leukocyte CD18 in several clinical disorders, at baseline and after in vitro activation.

SUBJECTS

we have examined subjects with type 1 diabetes mellitus, vascular atherosclerotic disease, type 2 diabetes mellitus without and with macrovascular complications, chronic renal failure on conservative treatment, essential hypertension, deep venous thrombosis, acute ischemic stroke and subjects with venous leg ulcers.

METHODS

unfractioned leukocyte suspension was prepared according to the Mikita's method, while the leukocyte were separated into mononuclear and polymorphonuclear cells with a Ficoll-Hypaque medium. Using specific monoclonal antibody, the CD18 expression was evaluated with cytofluorimetric analysis, using FACScan (Becton Dickinson) be Cellquest software; the activation in vitro with PMA was effected according to modified Yasui and Masuda methods.

RESULTS

in type 1 diabetes mellitus, at baseline CD18 is under expressed in comparison with normal control, and not changes after PMA activation were observed; in subjects with vascular atherosclerotic disease, in type 2 diabetes mellitus CD18 is over expressed at baseline but does not vary after activation; in subjects with chronic renal failure, essential hypertension and in subjects with acute ischemic stroke the CD18 up-regulate at baseline compared to normal control, and it increases further after activation; in subjects with deep venous thrombosis the CD18 expression is not different from control group at baseline, but it increases after activation; finally, in subjects with venous leg ulcers the CD18 is normally expressed at baseline, and it does not change after PMA activation.

CONCLUSIONS

in the different clinical disorders, the trend of this integrin subunit provides some specific information, useful to select the best therapeutic strategy in clinical practice.

Survival and analysis of predictors of mortality in patients undergoing replacement renal therapy: a 20-year cohort

Background

optimal management of end-stage renal disease (ESRD) in hemodialysis (HD) patients should be more studied because it is a serious risk factor for mortality, being considered an unquestionable global priority.

Methods

we performed a retrospective cohort study from the Nephrology Service in Brazil evaluating the survival of patients with ESRD in HD during 20 years. Kaplan-Meier method with the Log-Rank and Cox’s proportional hazards model explored the association between survival time and demographic factors, quality of treatment and laboratory values.

Results

Data from 422 patients were included. The mean survival time was 6.79 ± 0.37. The overall survival rates at first year was 82,3%. The survival time correlated significantly with clinical prognostic factors. Prognostic analyses with the Cox proportional hazards regression model and Kaplan-Meier survival curves further identified that leukocyte count (HR = 2.665, 95% CI: 1.39–5.12), serum iron (HR = 8.396, 95% CI: 2.02–34.96), serum calcium (HR = 4.102, 95% CI: 1.35–12.46) and serum protein (HR = 4.630, 95% CI: 2.07–10.34) as an independent risk factor for the prognosis of survival time, while patients with chronic obstructive pyelonephritis (HR = 0.085, 95% CI: 0.01–0.74), high ferritin values (HR = 0.392, 95% CI: 0.19–0.80), serum phosphorus (HR = 0.290, 95% CI: 0.19–0.61) and serum albumin (HR = 0.230, 95% CI: 0.10–0.54) were less risk to die.

Conclusion

survival remains low in the early years of ESRD treatment. The present study identified that elevated values of ferritin, serum calcium, phosphorus, albumin, leukocyte, serum protein and serum iron values as a useful prognostic factor for the survival time.

Effect of different dialysis modalities on microinflammatory status and endothelial damage

BACKGROUND AND OBJECTIVES

We studied the relationship between microinflammation and endothelial damage in chronic kidney disease (CKD) patients on different dialysis modalities.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Four groups of CKD stage 5 patients were studied: 1) 14 nondialysis CKD patients (CKD-NonD); 2) 15 hemodialysis patients (HD); 3) 12 peritoneal dialysis patients with residual renal function >1 ml/min (PD-RRF >1); and 4) 13 peritoneal dialysis patients with residual renal function <or=1 ml/min (PD-RRF <or=1). Ten healthy subjects served as controls. CD14(+)CD16(+) cells and apoptotic endothelial microparticles (EMPs) were measured by flow cytometry. Serum vascular endothelial growth factor (VEGF) was measured by ELISA.

RESULTS

CKD-NonD and HD patients had a higher percentage of CD14(+)CD16(+) monocytes than PD groups and controls. CD14(+)CD16(+) was similar in the PD groups, regardless of their RRF, and controls. The four uremic groups displayed a marked increase in apoptotic EMPs and VEGF compared with controls. Apoptotic EMPs and VEGF were significantly higher in HD patients than in CKD-NonD and both PD groups. However, there were no significant differences between CKD-NonD and the two PD groups. There was a correlation between CD14(+)CD16(+) and endothelial damage in CKD-NonD and HD patients, but not in PD and controls.

CONCLUSIONS

There was an increase in CD14(+)CD16(+) only in CKD-NonD and HD patients. In these patients, there was a relationship between increased CD14(+)CD16(+) and endothelial damage. These results strongly suggest that other factors unrelated to the microinflammatory status mediated by CD14(+)CD16(+) are promoting the endothelial damage in PD, regardless of their RRF.

Biocompatibility Study Based on Differential Sequestration Kinetics of CD14+CD16+ Blood Monocyte Subsets with Different Dialyzers

The immune defect in hemodialysis (HD) patients is associated with a monocyte dysfunction, including an increase in the production of proinflammatory cytokines. Blood membrane contact leads to an increase in cellular activation and sequestration into the capillary bed of the lung. The influence of the sequestration on the number of mature monocytes was studied by analyzing the fate of monocytes, particularly, the CD14+CD16+ subpopulation, during HD treatment. In thirty stable HD patients, the distinct cell populations were determined by differential blood counts and flow cytometry. Patients with diabetes or systemic vasculitis, those showing evidence of infectious complications or malignancy, or those taking immunosuppressive medications were excluded from the study. Cells from this study population were analyzed before the start, 30 min thereafter, and at the end of HD treatment, each time using a different dialyzer: hemophan, methylmethacrylate (PMMA), triacetate membrane, cuprophane/vitamin E, acrylonitrile, and sodium methallylsulfonate polymer (AN69). The CD14+CD16+ subset decreased at 30 min and remained suppressed for the course of dialysis. To examine whether currently used biocompatible membranes differ in their effect on the sequestration of monocyte subpopulations, temporal monocytic changes were comparatively analyzed during HD with a different dialyzer. The drop in the first 30 min until the end of HD treatment was significant (p<0.05), very uniform, and sharp in all patients, and was independent upon membrane type. The CD14+CD16+ monocyte subpopulation showed increased and longer margination from the blood circulation during HD. Given the fact that CD14+CD16+ monocytes represent a sensitive marker for inflammation or cellular activation, the depletion of these cells may offer an easily accessible parameter that is more sensitive than complement activation for biocompatibility studies on forthcoming, improved dialyzer membranes.

Immune function and leukocyte sequestration under the influence of parenteral lipid emulsions in healthy humans: a placebo-controlled crossover study

BACKGROUND

It remains unclear whether immune modulation by lipids contributes to the high risk of infectious complications that is associated with the use of parenteral nutrition. Although mixed long- and medium-chain triacylglycerol (LCT-MCT)-containing emulsions, but not pure LCT emulsions, activate neutrophils and impair crucial leukocyte functions in vitro, in vivo studies have failed to corroborate these findings.

OBJECTIVES

The present investigation was conducted to evaluate the effects of LCT and LCT-MCT on immune function in healthy humans and to assess whether the lack of in vivo effects results from sampling errors due to extravascular sequestration of activated neutrophils.

DESIGN

Saline, LCT-MCT, and LCT emulsions were administered intravenously for 4.5 h to 12 healthy volunteers in a randomized crossover design. Plasma triacylglycerol concentrations were clamped at a clinically relevant concentration of 3-5 mmol/L. Leukocyte population counts and neutrophil activation were assessed before and after infusion. Leukocyte sequestration was evaluated by monitoring the distribution of Technetium-99m-labeled autologous leukocytes during infusions.

RESULTS

Whereas LCT exerted no greater effects than did saline, LCT-MCT significantly decreased lymphocyte counts. However, no evidence for neutrophil activation was found with either lipid. Moreover, the clearance of radiolabeled leukocytes from the liver, spleen, and lungs was not altered by any lipid, which suggested that lipid emulsions do not induce leukocyte sequestration.

CONCLUSIONS

Short-term infusion of LCT-MCT (but not LCT) to healthy humans modulates leukocyte population counts but, in clear contrast with the in vitro situation, does not induce neutrophil activation. These disparate findings cannot be explained by MCT-induced leukocyte sequestration.

Effect of Hemodiafiltration on Pulmonary Hemodynamics in Endotoxic Shock

Hemofiltration can improve pulmonary hemodynamics during septic shock. The main objective of the study was to determine whether hemodiafiltration (HDF) would also have beneficial effects on pulmonary hemodynamics during septic shock. In the Endo group, six anesthetized pigs received a 0.5 mg/kg endotoxin infusion over 30 min. In the HDF group (n = 6), HDF was started 30 min after the end of the endotoxin infusion, while in the Control group (n = 4) they received HDF but no endotoxin infusion. Pulmonary hemodynamics were analyzed in detail with a four-element windkessel model. Although in the Control group, HDF did not alter pulmonary hemodynamic parameters, in the HDF group, it was responsible for an amplification of the deleterious pulmonary vascular response to endotoxin insult. Our results show that HDF must be used cautiously in septic shock since it can precipitate right heart failure by increasing pulmonary vascular resistance.

Effect of acetate-free biofiltration and bicarbonate hemodialysis on neutrophil activation

BACKGROUND

Activation of polymorphonuclear neutrophils (PMNs) and monocytes has been described during hemodialysis (HD), which results in the release of reactive oxygen species and cytokines. Acetate-free biofiltration (AFB) has been shown to cause less monocyte activation and cytokine release than bicarbonate HD (BHD). No data are available to date on the effect of AFB on PMN activation.

METHODS

We studied ex vivo superoxide anion release by PMNs isolated from nine patients treated in random order with AFB or BHD (three sessions each). Plasma interleukin-1beta (IL-1beta) levels and the nitric oxide (NO) synthetic pathway also were evaluated. A polyacrylonitrile (AN69; Hospal, Bologna, Italy) dialyzer was used for both treatments. Fourteen healthy volunteers were used as controls. Blood samples were drawn predialysis and 5 and 15 minutes after starting dialysis to obtain plasma and PMNs.

RESULTS

Neither ex vivo superoxide anion release nor blood PMN count was affected by AFB. Conversely, a peak in superoxide anion production associated with a decrease in PMN count was observed at 5 minutes during BHD. Results of superoxide anion production by control PMNs exposed in vitro to AFB or bicarbonate dialysis bath or Hank's balanced salt solution supplemented with bicarbonate or acetate indicated that BHD-induced PMN activation could be attributed to the amount of bicarbonate present in the dialysis bath. IL-1beta plasma levels did not change during dialysis with AFB and were numerically higher at 5 and 15 minutes with respect to predialysis values during BHD. Uremic plasma obtained during either AFB or BHD induced greater NO synthesis by human umbilical vein endothelial cells than control plasma.

CONCLUSION

AFB, unlike BHD, does not cause PMN and monocyte activation, which could have a positive impact on dialysis-associated cardiovascular disease of dialyzed patients.

Biocompatibility assessment of polytetrafluoroethylene/wollastonite composites using endothelial cells and macrophages

The aim of the study was to prepare a composite of polytetrafluoroethylene/wollastonite (PTFE/W) and evaluate its biocompatibility with endothelial cells. A composite of PTFE with wollastonite in the proportion 90/10 w/w was prepared. The dynamic storage modulus of composite is found to increase from 260 to about 453 MPa at room temperature while a marginal increase is observed in the compressive modulus. Higher values of storage modulus of PTFE/W relative to pristine PTFE over a range of temperature indicated the contribution of wollastonite in improving the rigidity of PTFE. Electron microscopic visualization of composite surface indicates suitable morphology for cell growth with the cross-section showing no evidence of bonding between PTFE and wollastonite. The water contact angle of the composite indicates increased hydrophilicity over native PTFE due to the presence of wollastonite. A direct-contact test did not show any deleterious effects on endothelial cell morphology and viability, indicating its compatibility. Leached-out products (LOP) from the composite were determined to be non-toxic as tested by tetrazolium (MTT) and Neutral red uptake (NRU) assays. Mouse peritoneal macrophages cultured in the presence of the composites did not show upregulation of activation markers such as CD11b/CD 18 (Mac-1), CD45, CD 14, and CD86 (B7.2) in comparison to macrophages cultured in contact with PTFE alone, indicating its non-activating nature. LOP did not induce proliferation of mouse splenic lymphocytes suggesting its immuno-tolerance. In static incubation assay contact with composite did not lead to hemolysis thus exhibiting preliminary hemocompatibility of the material. Suitable physico-chemical properties and well tolerance by endothelial cells and macrophages make this composite a prospective biomaterial. One could foresee the applications of this composite in areas where materials need to possess high rigidity and are subject to elevated temperatures.

The effect of LPS, uraemia, and haemodialysis membrane exposure on CD14 expression in mononuclear cells and its relation to apoptosis

BACKGROUND

Both uraemia and bioincompatible haemodialysis membranes induce mononuclear cell apoptosis. Recent reports demonstrate that spontaneous apoptosis in normal monocytes is associated with the down-regulation of CD14 molecules, whereas LPS which prevents the down-regulation of CD14 favours monocyte survival. The aim of the present study was to evaluate a possible association between mononuclear cell apoptosis and low expression of CD14 molecules. This study also investigated whether LPS affects mononuclear cell CD14 expression and the apoptosis induced by uraemia and exposure to Cuprophan (CU) membrane.

METHODS

The study was performed in vitro examining the effects of CU membrane and LPS on mononuclear cells from normal subjects and from end-stage renal failure patients. Cells were analysed by flow cytometry with fluorescent monoclonal antibodies to determine CD14 expression and with Annexin-V labelling to determine apoptosis.

RESULTS

In mononuclear cells from uraemic patients cultured for 48 h, there was a subset of cells with low CD14 expression; this subset of cells was not observed in normal monocytes cultured for the same period of time. Cells with low CD14 expression were also observed when normal or uraemic mononuclear cells were cultured in the presence of CU membrane. Simultaneous measurement of apoptosis and CD14 expression revealed that cells with low CD14 expression underwent apoptosis. The addition of LPS to the medium markedly reduced the number of mononuclear cells with low CD14 expression and also reduced the rate of apoptosis in these cells.

CONCLUSION

Our data suggest that mononuclear cell apoptosis induced by uraemia and the CU membrane is associated with low CD14 expression. Furthermore, LPS prevented the decrease in CD14 and reduced the rate of apoptosis.

Polyamide 6 composite membranes: properties and in vitro biocompatibility evaluation

The aim of the present study was to develop polyamide 6 membrane blended with gelatin and chondroitin sulfate using the phase precipitation method and evaluate its in vitro biocompatibility. Morphology of membranes was studied by laser scanning confocal microscopy which allowed the nondestructive visualization of internal bulk morphology of membranes. Membranes exhibited porous morphology with pores spanning across the membrane width with interconnections at various depths. Membranes showed adequate mechanical properties with tensile strengths of 20.10 +/- 0.64 MPa, % strain of 3.01+/-0.07, and modulus of 1082.50+/-23.50 MPa. In vitro biocompatibility of membranes by direct contact test did not show degenerative effects on NIH3T3 cells and also its leach-out products (LOP), as determined by tetrazolium (MTT) and neutral red uptake (NRU) assay. Mouse peritoneal macrophage cultured in contact with membranes and PTFE control showed comparable expression of activation markers such as CD11b/CD18, CD45, CD14, and CD86 suggesting the membranes' non-activating nature. Membrane LOP did not induce excessive proliferation of mouse splenocytes suggesting its non-antigenic nature. Preliminary blood compatibility of membranes was observed with no detectable hemolysis in static incubation assay. Taken collectively, the present data demonstrate that polyamide 6 composite membranes are biocompatible and prospective candidates for tissue engineering applications.

Selective sequestration of cytokine-producing monocytes during hemodialysis treatment

Hemodialysis treatment leads to leukocyte activation and cytokine production. Studying this effect has been complicated because cell activation by blood membrane contact also induces adherence factors on leukocytes, leading to margination of cells to the endothelium of the lung. Using single-cell cytokine determination, we studied the relation between cytokine production and cell sequestration during dialysis therapy. Blood was sampled in 11 chronic hemodialysis patients using hemophane dialyzers before hemodialysis and at 20 and 120 minutes of treatment. Lipopolysaccharide (LPS)-induced cytokine production in monocytes was studied by intracellular staining for interleukin-6 (IL-6) and IL-10 and flow cytometry. Results obtained in dialysis patients were compared with samples from an ex vivo dialysis system. Monocyte maturation stage was evaluated by detection of several surface markers through flow cytometry. Within 20 minutes of hemodialysis, the numbers of circulating monocytes decreased to one third of initial values. Before dialysis, 56.7% +/- 15.7% of circulating monocytes responded to LPS by the production of IL-6. This fraction decreased to 21.1% +/- 17.3% (P < 0.001 versus before hemodialysis) at 20 minutes and 32.3% +/- 13.8% (P < 0.001 versus before hemodialysis) at 120 minutes of treatment. A similar decrease occurred for IL-10. Cytokine-positive cells did not decrease during ex vivo dialysis. Surface marker studies showed that mature monocytes expressing HLA-DR or CD86 were predominantly removed. We provide the first evidence for a subtype-specific sequestration of monocytes caused by dialysis treatment. Fully differentiated cells capable of cytokine production and antigen presentation are removed and relatively immature cells remain in circulation.

Haemodialysis monocytopenia: differential sequestration kinetics of CD14+CD16+ and CD14++ blood monocyte subsets

In peripheral blood the majority of circulating monocytes present a CD14highCD16- (CD14++) phenotype, while a subpopulation shows a CD14lowCD16+ (CD14+CD16+) surface expression. During haemodialysis (HD) using cellulosic membranes transient leukopenia occurs. In contrast, synthetic biocompatible membranes do not induce this effect. We compared the sequestration kinetics for the CD14+CD16+ and CD14++ monocyte subsets during haemodialysis using biocompatible dialysers. Significant monocytopenia, as measured by the leucocyte count, occurred only during the first 30 min. However, remarkable differences were observed between the different monocyte subsets. CD14++ monocyte numbers dropped to 77 +/- 13% of the predialysis level after 15 min, increasing to > or = 93% after 60 min. In contrast, the CD14+CD16+ subset decreased to 33 +/- 15% at 30 min and remained suppressed for the course of dialysis (67 +/- 11% at 240 min). Approximately 6 h after the end of HD the CD14+CD16+ cells returned to basal levels. Interestingly, the CD14+CD16+ monocytes did not show rebound monocytosis while a slight monocytosis of CD14++ monocytes was occasionally observed during HD. A decline in CD11c surface density paralleled the sequestration of CD14+CD16+ monocytes. Basal surface densities of important adhesion receptors differed significantly between the CD14+CD16+ and CD14++ subsets. In conclusion, during HD the CD14+CD16+ subset revealed different sequestration kinetics, with a more pronounced and longer disappearance from the blood circulation, compared with CD14++ monocytes. This sequestration kinetics may be due to a distinct surface expression of major adhesion receptors which facilitate leucocyte-leucocyte, as well as leucocyte-endothelial, interactions.

Low levels of hepatitis C virus RNA in blood of infected patients under maintenance haemodialysis with high-biocompatibility, high-permeability filters

BACKGROUND

Patients undergoing maintenance haemodialysis are often infected with hepatitis C virus, yet the clinical course of liver disease is usually mild. We investigated whether the hepatitis C virus viral load is influenced by the haemodialytic procedure and the type of dialyser.

METHODS

Hepatitis C virus-RNA levels were measured using a quantitative polymerase chain reaction assay in predialysis blood from 51 hepatitis C virus-infected patients dialysed with different membranes. Paired pre- and post-dialysis measurements were also obtained in 18 patients.

RESULTS

Patients dialysed using cuprammonium-regenerated cellulose membranes with low (cuprofan) or intermediate (cellulose acetate or diacetate) biocompatibility had higher pre-dialysis hepatitis C virus-RNA levels (p<0.05] compared to those dialysed with synthetic high-biocompatibility, high-permeability polymeric membranes (polyacrylonitrile, polysulfone, polymethylmethacrylate or polycarbonate). Hepatitis C virus-RNA levels were unrelated to the duration of haemodialysis and the presence of abnormal transaminases. A significant reduction (p=0. 04) of serum hepatitis C virus-RNA levels was observed after a single haemodialysis, particularly in patients with high pre-dialysis viral load. Patients with low pre-dialysis hepatitis C virus-RNA levels (<2. 5 x 10(3) copies/ml) exhibited only minimal changes following the procedure. Four patients with medium-high basal viral load switched from a low-biocompatibility/low-permeability to a high-biocompatibility/high permeability filter had a marked reduction of viraemia after three weeks, in one case followed by a new increase after return to the original filter.

CONCLUSIONS

Haemodialysis with high-biocompatibility/high-permeability filters in hepatitis C virus-infected patients is associated with low blood levels of hepatitis C virus-RNA. This finding may be of clinical relevance, especially in patients listed for kidney transplantation.

Inhibition of a Membrane Complement Regulatory Protein by a Monoclonal Antibody Induces Acute Lethal Shock in Rats Primed with Lipopolysaccharide

Rats pretreated with traces of LPS developed acute fatal shock syndrome after i.v. administration of a mAb that inhibits the function of a membrane complement regulatory molecule. Such a shock was not observed after the administration of large amounts of LPS instead of the mAb following LPS pretreatment. The lethal response did not occur in rats depleted of either leukocytes or complement, and a C5a receptor antagonist was found to inhibit the reaction. Furthermore, LPS-treated rats did not suffer fatal shock following the injection of cobra venom factor, which activates complement in the fluid phase so extensively as to exhaust complement capacity. Therefore, complement activation on cell membranes is a requirement for this type of acute reaction.

In vivo generation of C4d, Bb, iC3b, and SC5b-9 after OKT3 administration in kidney and lung transplant recipients

BACKGROUND

OKT3 monoclonal antibody therapy results in an acute clinical syndrome (ACS) associated with the release of tumor necrosis factor and sequestration of neutrophils in the lungs. We have previously shown that inhibition of tumor necrosis factor does not completely eliminate OKT3-ACS, suggesting that other factors also contribute to the ACS. The current studies analyzed complement activation in vivo during the first hour after OKT3 administration.

METHODS

Renal (n=4) and lung (n=4) transplant recipients received OKT3 as treatment for rejection and induction therapy, respectively. Complement activation products C4d, Bb, iC3b, and SC5b-9 were measured by ELISA. Hemodynamic parameters were also monitored in the lung transplant recipients. Neutrophil expression of CD11a, CD11b, and CD18 was monitored by flow cytometry. Controls included patients receiving methylprednisolone for rejection (n=4), two adults with adult respiratory distress syndrome who received extracorporeal membrane oxygenation, and normal volunteers (n=5). P values less than 0.05 (*) were considered significant.

RESULTS

Increases in the plasma levels of C4d, Bb, iC3b, and SC5b-9 were observed in seven of eight patients after OKT3 administration. Mean values (n=8) at 0, 15, and 60 min (in microg/ml) were as follows-C4d: 1.865, 2.644*, and 2.607*; Bb: 0.245, 0.411, and 0.385; iC3b: 10.881, 17.242*, and 15.145*; and SC5b-9: 0.232, 0.269, and 0.302*. An increase in CD11b and CD18 and a decrease of CD11a on neutrophils in parallel with complement activation was observed. In lung transplant recipients, C3 activation correlated with increases in mean pulmonary and central venous pressures (P<0.05). As compared with extracorporeal membrane oxygenation, which activated classical and alternative pathways, OKT3 predominantly activated complement by the classical pathway. Methylprednisolone pulses did not activate complement.

CONCLUSIONS

Complement activation is an early event after OKT3 administration and is associated with the increased expression of adhesion molecules on neutrophils and with pulmonary hemodynamic changes. Effective therapeutic approaches to the control of early monoclonal antibody side effects may require measures that limit complement activation in addition to reducing cytokine activity.