Production of cytokines in hemodialysis

Molecular epidemiology and associated risk factors of oral cavity parasites in hemodialysis patients in western Iran

Renal disorders are able to make patients more susceptible to infections, including those caused oral cavity infections. Today, it has been proven that during end stage renal failure, hemodialysis results in acquired immune response defects through failings of humoral and cell-mediated immune. This survey was intended to assess the molecular epidemiology and associated risk factors of Entamoeba gingivalis and Trichomonas tenax as the main oral cavity protozoa in hemodialysis patients in Lorestan Province, western Iran. The investigation was performed on 73 hemodialysis patients referring to hemodialysis centers of Lorestan Province, Iran during May 2021 to February 2022. The frequency of oral cavity protozoa was investigated using microscopic and conventional polymerase chain reaction (PCR). A provided questionnaire with a number of demographical information and related risk factors was completed for each patient. The results showed that E. gingivalis and T. tenax parasites were found in 18 (24.6%) and 20 (27.4%) of the hemodialysis participants by microscopic and PCR test, respectively. Among samples, 13 (17.8%) of the hemodialysis participants were infected with E. gingivalis; whereas 7 (9.6%) of the participants were positive for T. tenax. No significant association was reported between gender, age, education, flossing, use of mouthwash, and prevalence of oral protozoa in hemodialysis participants. However, a significant correlation was observed among between living in rural regions (OR = 13.16; 95% CI = 2.64-56.81; p = 0.002), brushing teeth (OR = 8.51; 95% CI = 1.71-42.3; p = 0.009) and prevalence of oral protozoa in hemodialysis participants. The findings of these epidemiological study clearly showed the high frequency of oral cavity parasites in hemodialysis patients in Lorestan Province, Western Iran. Awareness of the main risk factors for oral cavity parasites particularly teeth brushing is necessary in refining public and oral health policies in hemodialysis patients. Consequently, dental practitioners, nephrologist, and urologist must be alert of these risk factors to carefully identify and achieve oral health concerns in hemodialysis patients to prevent the oral diseases and infections.

Opportunistic parasitoses among Egyptian hemodialysis patients in relation to CD4+ T-cell counts: a comparative study

Background

Some reports are available on the prevalence of opportunistic parasitoses among hemodialysis (HD) patients, yet there is a paucity of data on the association of CD4+ T-cell counts with such infections. Therefore, this study aimed to determine the prevalence of intestinal parasites and Toxoplasma gondii in relation to CD4+ counts among HD patients in Alexandria, Egypt.

Methods

A comparative cross-sectional study was conducted on 120 HD patients and 100 apparently healthy individuals between December 2014 and January 2016. Data and samples (stool and blood) were collected from the participants after obtaining their informed consent. Stool samples were examined for parasites after concentration and staining, EDTA-blood samples were used for CD4+ counting by flow cytometry, and sera were analyzed for anti-Toxoplasma IgM and IgG antibodies.

Results

A significantly higher prevalence rate of intestinal parasitoses was found among HD patients compared to apparently healthy individuals (52.5% vs. 12.0%, respectively), with absence of helminths. Cryptosporidium species (32.5%), B. hominis(24.2%) and microsporidia (11.7%) were the most frequent parasites among HD patients, while B. hominis (13.0%), Cryptosporidium species (11.0%) and G. lamblia (4.0%) were the most frequent parasites among their counterparts. Statistically significant differences in parasite infection rates between patients and their counterparts were found for Cryptosporidium species, B. hominis and microsporidia. However, parasite species were not significantly associated with diarrhea. On the other hand, the overall T. gondii seroprevalence rate among HD patients was significantly higher than that among their counterparts (33.3% vs. 8%, respectively). HD patients with CD4+ counts < 200 cells/μl were twice more exposed to intestinal parasitoses compared to those with counts ≥200 cells/μl, but the difference was not statistically significant. However, low CD4+ counts were significantly associated with higher rates of Cryptosporidium species, microsporidia and T. gondii.

Conclusions

Intestinal parasitoses and T. gondii infection rates are significantly higher among Egyptian HD patients compared to apparently healthy individuals, with Cryptosporidium species, B. hominis, microsporidia and T. gondii being the most frequent parasites. CD4+ counts < 200 cells/μl are significantly associated with Cryptosporidium species, microsporidia and T. gondii among HD patients. Therefore, regular screening of HD patients for opportunistic parasites is recommended.

Effects of Dialysis Membranes on the Kinetics of Tumor Necrosis Factor-α Production by Peripheral Mononuclear Cells in Chronic Hemodialysis Patients

To evaluate the biocompatibility of dialysis membranes, blood samples were collected from 10 hemodialysis patients immediately before dialysis and peripheral blood mononuclear cells were isolated. The 3.0 x 105 cells/ml were then passed 30 times through modules made of a polyethylene glycolgrafted cellulose membrane, a polyacrylonitrile membrane, and a polysulfone membrane. Expression of messenger RNA for tumor necrosi factor-α (TNF-α) was determined. Cells were also cultured for 2 h with and without lipopolysaccharide and TNF-α levels in the supernatant were measured.

TNF-α messenger RNA expression was significantly higher immediately after passage through the polyacrylonitrile membrane compared with the other membranes. Cells cultured without lipopolysaccharide, produced significantly less TNF-α after passage through the polysulfone membrane, while lipopolysaccharide significantly increased TNF-α production by cells passed through the polyacrylonitrile membrane. These results suggest that biocompatibility differs even among dialysis membranes believed to cause no complement activation.

Variables Associated with the Assessment of Systemic Tumor Necrosis Factor Alpha Levels during Hemodialysis

Conflicting results have been published concerning the systemic induction of the cytokine tumor necrosis factor alpha (TNFα) during hemodialysis (HD). We therefore evaluated in vitro TNFα production in whole blood as well as in vivo variability of TNFα levels in patients on long-term HD. Whole blood was incubated at room temperature (RT) with or without exogenously added endotoxin (ET), and plasma-TNFα was measured after 5, 30, 120, 240, and 960 min by specific enzyme immunoassay. Additionally, plasma-TNFα before and after 120 and 240 min HD was studied longitudinally once a week over a period of 4 weeks in 36 patients on Cuprophan® (CU, n=23) or polysulfone-F60 (PSu, n=13) HD. Mean plasma TNFα levels in vitro rose from (mean) 8 pg/ml after 5 min to 12 pg/ml (120′) and 32 pg/ml (960′) even without ET addition, and to 18 pg/ml (after 120′) and 88 pg/ml (after 960′) when 0.1 μg/ml ET were added. Pre-dialytic as well as intradialytic TNFα levels in patients showed high intra-individual variability. A substantial (> 100%) increase in plasma TNFα was observed during only 14 out of 84 treatments with CU and 20 out of 47 with PSu, however, the increase in TNFα was not statistically significant in either group. We conclude that the sampling procedure, if not carefully standardized, is a potential source of artifacts with regard to “systemic” TNFα levels. The high intra and inter-individual variability of plasma TNFα suggests that results of cross-sectional studies are questionable.

Monocyte Activation and Humoral Immune Response to Endotoxins in Patients Receiving On-Line Hemodiafiltration Therapy

With the on-line preparation of substitution fluid, an easy-to-operate and cost-effective alter-native to conventional hemodiafiltration (HDF) has been realized. The continuous filtration of dialysis fluid, furthermore, allows high volumes of exchange. Microbial contamination and subsequently endotoxins, however, may be present in dialysis fluid, and thus the microbiological safety has become a pivotal issue.

In this clinical study we evaluated the safety of the Fresenius Medical Care on-line HDF system which is based on a two-stage filtration of dialysis fluid with upstream DIASAFE® and downstream on-line HDF filter. During the three-month study period we failed to detect germs or endotoxins in the substitution fluid. Augmented plasma interleukin-1β (IL-1β) and tumor necrosis factor α (TNFα) concentrations were found neither during the intradialytic period nor when pre-session values at study begin and study end were compared. In addition, changes in the anti-endotoxin core antibody levels and soluble CD14 (sCD14) concentration, or pyrogenic episodes were not observed.

On-line HDF with DIASAFE® and on-line HDF filter thus represents a safe treatment modality by effectively depleting dialysis fluid of cytokine-inducing substances.

Production of interleukin 1 receptor antagonist and interleukin 1 during haemodialysis with cellulose membranes

An in vivo cross-over study has investigated plasma and cellular levels of IL-1 (IL-1α IL-1β and IL-1Ra) when using Cuprophan (C) and cellulose triacetate (CTA) membranes to assess the roles of complement activation and dialysate endotoxin content in the induction of cytokines during the dialysis procedure. The mean C5a level during Cuprophan dialysis was 29.9 ± 0.63 ng/ml (Mean ± SEM), while for the cellulose triacetate dialysis was 3.09 ± 0.7 ng/ml. The endotoxin content of the dialysate was 0.31 ± 0.34 EU/ml and 0.68 ± 1.39 EU/ml. These two factors failed to produce measurable changes in plasma or cellular IL-1α and IL-1β levels during treatment. The plasma IL-1Ra levels pre-dialysis were similar to those for normal controls (CTA 769 ± 156 ng/ml, C739 ± 93, normal controls 635 ± 33) with a considerable day to day variation. A membrane independent fall in plasma IL-1Ra at 15 minutes was noted (CTA 420 ± 92 ng/ml, C 503 ± 139) with a return to pre-dialysis levels by the end of treament. Cellular IL-1Ra levels pre-dialysis were similar to the normal group - (CTA 1904 ± 291 ng/ml, C 1564 ± 292 and normal control 1971 ± 368). However, on average, the values when using cellulose triacetate were 655 ± 623 pg/ml higher than for Cuprophan (p=0.03). These findings indicate that the measurement of plasma cytokine levels is of limited use in the study of cytokine induction by the haemodialysis procedure and that IL-1Ra may be a better indicator of the host response to cytokine stimuli during treatment. However, a considerable inter-patient and intra-treatment variation is present and further studies are required to elucidate the factors involved.

Blood Contact with Artificial Surfaces during BVAD Support

Persistently elevated levels of cytokines (IL-6, IL-8) during the course of mechanical circulatory support correlate well with fatal outcome. To determine the influence of blood/artificial surface interaction on the chronic inflammatory process, we studied the biocompatibility of silicone and polyurethane membranes in vitro. Cultures of isolated mononuclear cells or whole blood were incubated for 24 hours in tubes coated with silicone or polyurethane, both used in the construction of ventricular assist systems. Concentrations of several inflammatory mediators were measured in the supernatant. Our results can be summarized as follows: a) Monocytes were stimulated to release inflammatory cytokines like IL-8 and MIP-1α, particularly when silicone was involved; b) Both silicone and polyurethane stimulated thrombocytes thus resulting in the release of P-Selectin and PDGF-AB, although polyurethane was a stronger stimulus; c) Moderate complement activation was triggered by contact with either of the artificial surfaces. However, the prevention of most of these effects by coating the artificial surface with protein and the lack of correlation between in vitro data and serum levels of IL-6 and IL-8 during the course of circulatory support suggest that the persistence of inflammatory cytokines during BVAD support is not caused by blood/surface interaction.

A New Polymethylmethacrylate Membrane for Hemodialysis

High molecular weight (MW) solutes are not removed during conventional hemodialysis (HD), and their accumulation is thought to play a role in some long-term HD complications (anemia, bone and joint pain, neuropathy, itching). The present trial was conducted to evaluate the removal capacity during in vivo HD of a new polymethylmethacrylate (PMMA) membrane (Filtryzer BK-F, 1.3 m2) compared to conventional PMMA (BK-P, 1.6 m2) and to cellulose acetate (CA, 1.3 m2). BK-F dialyzers, with a pore size of 100 A° and 62% porosity, are designed to remove high MW substances. Ten stable anuric RDT patients (53 ± 13 years) were treated for one week with each membrane in a randomized sequence. Plasma concentrations of creatinine, BUN and beta2-microglobulin (beta2-M) were measured before (b) and after (a) HD to determine the reduction rate for these substances (%). Beta2-M concentration after HD was corrected for changes in distribution volume. Samples of spent dialysate were collected after 3 minutes, 120 minutes and at the end of HD sessions, and appropriately treated and concentrated for HPLC analysis. The reduction rate for BUN and creatinine was similar for the 3 membranes. BK-F showed a higher beta2-M reduction rate than BK-P (p<0.005) or CA (p<0.0001). HPLC analysis of dialysate showed prevalent peaks < 4 kilodaltons (kDa) throughout HD for BK-P and CA. Solutes > 10 kDa were infrequently detected. Peak profile during HD with BK-F was quite different, showing a predominant peak > 50 kDa which also included albumin. However, albumin loss significantly decreased after 120 minutes and at the end of dialysis compared with the 3-minute values, and was lower than that reported in CAPD patients. With BK-F a peak of MW > 500 kDa was also detected which previous studies indicated as a range characterized by the presence of erythropoiesis inhibitors. Use of the BK-F membrane in HD could afford satisfactory removal of high MW substances, thereby preventing or controlling some long-term HD complications such as anemia or beta2-M amyloid formation.

Hemodialysis affects phenotype and proliferation of CD4-positive T lymphocytes

CD4⁺ T lymphocytes of patients with chronic kidney disease (CKD) are characterized by reduced levels of crucial surface antigens and changes in the cell cycle parameters. Recombinant human erythropoietin (rhEPO) normalizes their altered phenotype and proliferative capacity. Mechanisms leading to the deficient responses of T lymphocytes are still not clear but it is postulated that immunological changes are deepened by hemodialysis (HD). Study of activation parameters of CD4⁺ T lymphocytes in hemodialyzed and predialysis CKD patients could bring insight into this problem. Two groups of patients, treated conservatively (predialysis, PD) and hemodialyzed (HD), as well as healthy controls, were included into the study; neither had received rhEPO. Proportions of main CD4⁺CD28⁺, CD4⁺CD25⁺, CD4⁺CD69⁺, CD4⁺CD95⁺, and CD4⁺HLA-DR⁺ lymphocyte subpopulations and proliferation kinetic parameters were measured with flow cytometry, both ex vivo and in vitro. No differences were seen in the proportions of main CD4⁺ lymphocyte subpopulations (CD4⁺CD28⁺, CD4⁺CD25⁺, CD4⁺HLA-DR⁺, CD4⁺CD69⁺, CD4⁺CD95⁺) between all examined groups ex vivo. CD4⁺ T lymphocytes of HD patients exhibited significantly decreased expression of co-stimulatory molecule CD28 and activation markers CD25 and CD69 after stimulation in vitro when compared with PD patients and healthy controls. HD patients showed also decreased percentage of CD4⁺CD28⁺ lymphocytes proliferating in vitro; these cells presented decreased numbers of finished divisions after 72 h of stimulation in vitro and had longer G0→G1 time when compared to healthy controls. CD4⁺ T lymphocytes of PD patients and healthy controls were characterized by similar cell cycle parameters. Our study shows that repeated hemodialysis procedure influences phenotype and proliferation parameters of CD4⁺ T lymphocytes.

Recombinant human erythropoietin treatment of chronic renal failure patients normalizes altered phenotype and proliferation of CD4-positive T lymphocytes

Patients with chronic renal failure (CRF) receive recombinant human erythropoietin (rhEPO) for the correction of anemia. However, rhEPO also has an immunomodulatory effect. Detailed changes of phenotype and function of CD4(+) T lymphocytes in CRF patients receiving rhEPO have not been reported yet; their study may bring insight into understanding of this immunomodulatory action of rhEPO. Two groups of CRF patients were included into the study: those treated; and those not receiving rhEPO. The expression of activation markers on CD4(+) lymphocytes was measured with flow cytometry, both ex vivo and in vitro. The kinetics of CD4(+) T lymphocytes proliferation was calculated using a dividing cells tracing method and numerical approach. Significantly higher percentages of CD4(+)CD95(+), CD4(+)HLA-DR(+) cells, and lower percentages of CD4(+)CD69(+) and CD4(+)CD28(+) cells were observed in both rhEPO-treated and untreated patients when compared with healthy controls. Changes in the proportions of CD4(+)CD28(+) and CD4(+)HLA-DR(+) subpopulations were dependent on the type of rhEPO, being more pronounced for rhEPObeta. CD4(+) lymphocytes from untreated patients exhibited decreased expression of CD28 and CD69 after stimulation in vitro, whereas the expression of these antigens on lymphocytes of rhEPO-treated patients was similar to that observed in healthy controls. Fewer CD4(+)CD28(+) T lymphocytes of untreated patients proliferated in vitro; these cells had longer G0-->G1 time, which negatively correlated with surface expression of CD28. Our study confirms that rhEPO treatment normalizes activation parameters of CD4(+) T lymphocytes and their proliferative capacity, which could explain earlier described immunomodulatory effects of rhEPO in patients suffering from CRF.

Elevation of Pro-Inflammatory Cytokines, C-Reactive Protein and Cardiac Troponin T in Chronic Renal Failure Patients on Dialysis

Chronic renal failure (CRF) patients suffer from a chronic inflammation. They are at increased risk of cardiovascular disease. In order to investigate this inflammatory process and cardiovascular risk factors associated with haemodialysis (HD) and peritoneal dialysis (PD), we compared serum/plasma pro-inflammatory cytokines, C-reactive protein (CRP), and cardiac troponin T (cTnT) of 146 CRF patients treated or not treated with PD or HD. Serum cytokines and CRP as well as plasma cTnT were measured by enzyme-linked immunosorbent assay, chemiluminescence immunoassay, and electrochemiluminescence immunoassay, respectively. Results indicated that serum interleukin (IL)-18 concentrations were significantly higher in PD and low creatinine clearance pre-dialysis CRF (LCC) patients than HD patients (both p < 0.05). IL-6 and tumour necrosis factor (TNF)-alpha concentrations were significantly higher in PD patients than LCC patients (both p < 0.01). Serum hsCRP and plasma cTnT in HD were significantly higher than LCC (both p < 0.01). The elevation of pro-inflammatory cytokines should play an important role in the chronic inflammation and increased cardiovascular risk of CRF patients on dialysis. We are evaluating further the diagnostic and prognostic applications of pro-inflammatory cytokines and biochemical inflammatory markers for these patients.

Serum Growth Factors in Hemodialyzed Patients

The contact of chronic hemodialysis patients' blood with components of extracorporeal circulation leads to mobilization of several systemic reactions. The purpose of this study was to determine the activity of transforming growth factor (TGF-beta1) and platelet derived growth factor (PDGF) in serum of patients on long-term hemodialysis program and to compare these results with ones obtained in healthy volunteers. Twenty-five patients on dialysis carried out on polysulfone membrane dialyzer, and 16 patients on dialysis with the used of cuprophan membrane dialyzer on long-term hemodialysis program participated in the study. TGF-beta1 level in serum of healthy volunteers (12.06 +/- 7.56 ng/mL) was lower than in serum of patients dialyzed on polysulfone membrane dialyzers (26.56 +/- 14.83 ng/mL). Differences in PDGF concentrations in serum of control group and hemodialyzed patients were not statistically significant. The strong correlation between TGF-beta1 and PDGF in serum of both studied groups of patients was demonstrated.

Polymethylmethacrylate efficacy in reduction of renal itching in hemodialysis patients: crossover study and role of tumor necrosis factor-alpha

Pruritus is one of the major unsolved problems for patients receiving regular hemodialysis. In this study, we conducted a 6 month prospective and crossover trial to investigate the effect of polymethylmethacrylate (PMMA) membrane for renal itching. We also examined the role of the tumor necrosis factor (TNF)-alpha system for pruritus in hemodialysis patients. We assessed the degree of skin itching and measured circulating levels of TNF-alpha and soluble TNF receptors (sTNFR-I, sTNFR-II) in 19 patients using hemodialysis, complicated by prolonged severe pruritus for 6 months. Serum sTNFR-I and II levels were significantly elevated in hemodialysis patients compared to normal subjects. Serum sTNFR-II levels were significantly and negatively correlated with serum albumin (r = -0.602, p = 0.007). A significant positive relationship was also found between sTNFR-I and erythropoietin dosage (r = 0.554, p = 0.016). However, no association was found between the degree of pruritus and circulating sTNFR-I and II values. Skin itching scale was significantly decreased from 2.7 +/- 0.2 to 2.1 +/- 0.3 following the use of PMMA membrane for 3 months (p < 0.05). In contrast, there was no change in itching scales during 3 months of conventional therapy (2.2 +/- 0.3 versus 2.2 +/- 0.3, p = NS). PMMA itself did not affect serum TNF-alpha and sTNFR values as well as conventional dialyzer membranes. These findings suggested that the PMMA dialyzer can improve renal itching not mediated through the modification of the TNF-alpha system.

Evidence in vivo showing increase of baseline nitric oxide generation and impairment of endothelium-dependent vasodilation in normotensive patients on chronic hemodialysis

Cardiovascular mortality is excessive in hemodialyzed patients. Observations in atherosclerosis suggest that endothelial dysfunction and impaired nitric oxide (NO) may be involved. However, the relation of endothelial NO to its vascular effects has not been studied conclusively in uremia. Therefore, to study these questions an invasive technique was used in normotensive patients who were on hemodialysis (HD; n = 11) and in matched control subjects (n = 11). Pharmacologic agents were infused into the brachial artery to test the chain of events from NO generation to smooth muscle cell relaxation, measuring forearm blood flow by venous occlusion plethysmography. Glyceroltrinitrate (GTN 1:2.2 nmol/min; GTN 2:4.4; GTN 3:8.8), infused to establish the reaction of the vessel wall to defined doses of NO, caused a reduced response in HD patients (control subjects: 183 +/- 20 [SEM], 246 +/- 26, and 338 +/- 29%; HD patients: 161 +/- 7, 206 +/- 12, and 262 +/- 24%; baseline = 100% for each group, P: = 0.032 by ANOVA). All subsequent data were corrected for this decreased response to defined doses of NO in HD patients. L-arginine (10 mg/min), given to exclude substrate deficiency of NO synthase (NOS), caused no significant changes (control subjects: 108 +/- 4%; HD patients: 103 +/- 4%; P: = NS). Acetylcholine (ACH 1:55 nmol/min; ACH 2:110; ACH 3:220), infused to stimulate endothelial NOS, had a significantly reduced effect in HD patients (control subjects: 246 +/- 32, 340 +/- 40, and 465 +/- 52%; HD patients: 251 +/- 55, 244 +/- 36, and 318 +/- 50%; P: = 0.002). N:-monomethyl-L-arginine (LMA 1:1 micromol/min; LMA 2:2; LMA 3:4), given to block baseline NO generation, showed an enhanced response in HD patients (control subjects: 90 +/- 2, 83 +/- 2, and 74 +/- 4%; HD patients: 84 +/- 3, 73 +/- 3, and 64 +/- 4%; P: = 0.037). Vascular response to three doses of norepinephrine (60, 120, and 240 pmol/min) was comparable in both groups, which indicated similar endothelium-independent vasoconstriction. In summary, in normotensive HD patients, (1) vasodilation to defined doses of exogenous NO was reduced, (2) there was no evidence of substrate deficiency of NOS, and (3) stimulation of NOS was impaired; however, (4) baseline NO generation was increased. It is concluded that in HD patients, the NO system has a reduced capacity to regulate vascular tone and this impairment is most significant under conditions of NOS stimulation.

Clinical relevance of cytokine production in hemodialysis

Blood-dialyzer interaction in hemodialysis has the potential to activate mononuclear cells leading to the production of inflammatory cytokines. The extent of activation is dependent on the dialyzer material used and is considered an index of biocompatibility. Cytokines, such as interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), and IL-6, may induce an inflammatory state and are believed to play a significant role in dialysis-related morbidity. The interleukin hypothesis suggests that the release of proinflammatory cytokines acts as an underlying pathophysiologic event in hemodialysis-related acute manifestations, such as fever and hypotension. Nevertheless, a cytokine overproduction may alter sleep pattern in chronic hemodialyzed patients, thus explaining the presence of sleep disorders in these patients. A potential role of cytokines in chronic-related morbidity has also been suggested. High levels of some inflammatory cytokines are often associated with anemia caused by hyporesponsiveness to erythropoietin. Cytokine production may also play a relevant role in bone remodeling by regulating osteoblast/osteoclast cell functions and parathyroid hormone (PTH). Finally, cytokine release may have a long-term deleterious effect on mortality of uremic patients by altering immune response and increasing susceptibility to infections. Bioincompatibility of dialytic membranes may also contribute to malnutrition in dialysis patients by increasing the monocyte release of catabolic cytokines such as TNF-alpha and IL-6. Bioincompatible dialytic treatment may induce an inappropriate monocyte activation and cytokine production, which, in turn, may mediate some of the immune and metabolic dysfunction associated with hemodialysis. The use of biocompatible dialytic membranes appears to reduce the monocyte activation and to improve the survival of hemodialysis patients.

Cytokine induction in patients undergoing regular online hemodiafiltration treatment

End-stage renal disease (ESRD) patients are known to suffer from chronic inflammation as the result of an ongoing subacute cytokine induction, which may contribute considerably to dialysis-related, long-term morbidity and mortality. Preparation of infusate from cytokine-inducing dialysis fluid and its administration in large quantities as well as the use of high-flux membranes bear the risk of aggravating the chronic inflammatory response among online hemodiafiltration (online HDF) patients. In order to assess the inflammatory risk associated with online HDF, we compared the cytokine induction profile of ESRD patients receiving either online HDF or low-flux hemodialysis (low-flux HD). Specifically, we measured spontaneous and lipopolysaccharide (LPS)-stimulated tumor necrosis factor alpha (TNFalpha) and interleukin-1 receptor antagonist (IL-1Ra) release during ex vivo incubation of whole blood. Ultrapure dialysis fluid and polysulfone membranes were used for both treatment modalities. LPS-stimulated release of TNFalpha and IL-1Ra was elevated for both online HDF and low-flux HD patients compared to healthy individuals (TNFalpha: 2,336 +/- 346 and 2,192 +/- 398 versus 1,218 +/- 224 pg/106 white blood cells [WBC]; IL-1Ra: 2,410 +/- 284 and 2,326 +/- 186 versus 1,678 +/- 219 pg/106 WBC). Likewise, spontaneous production of TNFalpha, but not IL-1Ra, was higher in online HDF and low-flux HD patients than in normal controls (37 +/- 32 and 22 +/- 19 versus 0.8 +/- 0.3 pg TNFalpha/106 WBC). There was no difference in spontaneous and LPS-stimulated cytokine release between both dialysis groups. In addition, intradialytic cytokine induction was not significant for either treatment modality as spontaneous and LPS-stimulated cytokine release were not increased postdialysis. These findings indicate that online HDF does not contribute to chronic leukocyte activation and, consequently, does not place ESRD patients at greater risk with respect to inflammatory morbidity and mortality.

Influence of dialysis membranes on interleukin-1 beta and interleukin-1 receptor antagonist production by peripheral blood mononuclear cells

We investigated the production of interleukin (IL)-1 beta and IL-1 receptor antagonist (Ra) by peripheral blood mononuclear cell (PBMC) in vitro during hemodialysis of 7 dialysis patients using 4 differential dialysis membranes (regenerated cellulose [RC], polyamide [PA], polysulfone [PS] and AN-69). Blood sampling was performed before dialysis (0 min), 15 min after starting dialysis, and after dialysis (240 min) during the last session of each treatment. The cellular content of fresh cells and the production of IL-1 beta and IL-1Ra with and without lipopolysaccharide (LPS) stimulation of the cells were evaluated and measured by enzyme-linked immunosorbent assay (ELISA). The level of IL-1 beta with LPS stimulation using RC, PA, and PS membranes was significantly reduced at 15 min and was not changed at 240 min as compared with the level at 0 min. On the other hand, the level of IL-1 beta with LPS stimulation using an AN-69 membrane at 15 and 240 min was not significantly different from that at 0 min. Neither initial cellular content nor spontaneous production of IL-1 beta were detected at 0, 15, or 240 min in any of the membranes. The spontaneous production of IL-1Ra at 15 and 240 min was not significantly different from that at 0 min in any of the membranes. The cellular content of IL-1Ra using the RC membrane was significantly lower at 15 min and did not differ at 240 min from the level at 0 min. The cellular content of IL-1Ra using PA, PS, and AN-69 membranes was not significantly different at 15 and 240 min from that at 0 min. However, the IL-1Ra level with LPS stimulation using RC and PA membranes was significantly reduced from that at 0 min, but the level using PS and AN-69 membranes was not different from that at 0 min. Because IL-1 beta and IL-1Ra levels 15 min after starting dialysis using bioincompatible dialysis membranes were reduced from the levels at 0 min, the findings suggest that measurement of cytokines' during dialysis treatment at an early stage is a useful marker for evaluating the biocompatibility of a dialysis membrane.

Influence of hemodialysis membranes on gene expression and plasma levels of interleukin-1 beta

Plasma levels of interleukin-1 beta (IL-1 beta) were measured in 10 normal subjects, in 11 nondialyzed end-stage renal failure (ESRD) patients, and in 22 hemodialysis (HD) patients. Of the HD patients, 7 were dialyzed with Cuprophan (CU), 7 with polymethylmethacrylate (PMMA), and 8 with polysulphone (PS) dialyzers. In normal controls, nondialyzed ESRD patients, and HD equipped with CU, PAMM, and PS dialyzers, plasma levels of IL-1 beta were 10.73 +/- 5.24 pg/ml, 9.97 +/- 3.61 pg/ml, 13.17 +/- 4.04 pg/ml, 15.16 +/- 6.16 pg/ml, and 13.96 +/- 5.47 pg/ml, respectively. There were no statistically significant differences among the groups (p > or = 0.05). In contrast, the gene expression of IL-1 beta for peripheral blood mononuclear cells (PBMC) by in situ hybridization showed differences among the groups. The gene for IL-1 beta for PBMC appears in HD equipped with different membranes, but not in cases of nondialyzed uremic patients and normal subjects. With computer imaging analysis, we carried out quantitative analysis of cells in in situ hybridization with an area of positive spots to an area of total cells. In HD with CU, PMMA, and PS, the results were 10.64 +/- 1.07, 3.34 +/- 0.74, and 3.27 +/- 0.64%, respectively. The levels of IL-1 beta gene expression in CU were higher than that in PMMA or PS. There were statistically significant differences (p < or = 0.001) between CU and PMMA or PS and no significant difference between the PMMA and PS (p > or = 0.05). We suggest measuring the gene expression of cytokines for PBMC and which may be better than measuring cytokine levels only for investigating the blood compatibility of dialyzers, which may help in understanding chronic complications of the dialysis procedure.

Interleukin-6 and interleukin-8 extraction during continuous venovenous hemodiafiltration in septic acute renal failure

OBJECTIVES

To determine whether continuous venovenous hemodialfiltration (CVVHD) is associated with the extraction of interleukin-6 (IL-6) and interleukin-8 (IL-8) from the circulation of critically ill patients with septic acute renal failure. To quantitate their clearance and assess any possible effect of CVVHD on these cytokines' serum concentrations.

DESIGN

Prospective controlled study of IL-6 and IL-8 removal by CVVHD in patients with septic acute renal failure.

SETTING

Intensive care unit of a tertiary institution.

PATIENTS

Ten critically ill patients with sepsis, acute renal failure, and multiorgan failure. A control group of five patients experiencing an acute illness while undergoing chronic hemodialysis.

INTERVENTIONS

Collection of blood samples before CVVHD. Simultaneous collection of prefilter blood and ultradiafiltrate after 4 and 24 h of treatment. IL-8 concentrations were measured in blood and ultradiafiltrate. Their clearances and daily extractions were calculated.

MEASUREMENTS AND MAIN RESULTS

IL-6 and IL-8 were detected in the blood of all patients with septic acute renal failure prior to CVVHD. The median IL-6 blood level was 103 pg/mL (range: 19 to 900) and the median IL-8 blood level was 200 (range: 32 to 2925). Both cytokines were cleared by the hemofilter during CVVHD. The median hemofilter clearance of IL-6 were 1.99 L/day (range: 0 to 8.5) and the median clearance of IL-8 was 3.95 L/day (range: 0.31 to 42.8). These blood levels and clearances resulted in median daily extraction rates of 194 ng of IL-6 (range: 0 to 9031) and of 915 ng of IL-8 (range 47.5 to 3562). Control patients had negligible amounts of either IL-6 or IL-8 in their ultrafiltrate. The rate of extraction for IL-6 correlated with its blood levels (p < 0.0001). This was not true for IL-8. A correlation between IL-6 levels and the patients' white cell counts was found after 24 h of hemofiltration.

CONCLUSIONS

CVVHD is associated with the extraction of IL-6 and IL-8 from the circulation of patients with septic multiorgan and renal failure. The biological significance of such extraction is undetermined, but such cytokine removal highlights the complexity of the effect of continuous hemofiltration on the soluble mediators of inflammation activated during human sepsis.

Comparison of first use and reuse of cuprophan membranes on interleukin-1 receptor antagonist and interleukin-1 beta production by blood mononuclear cells

The magnitude of the changes in a variety of blood constituents on exposure to the dialysis membrane has been used as an index of "biocompatibility," and dialyzer reuse has been postulated to improve biocompatibility by attenuating these changes. We studied the hemodialysis-induced changes in the in vitro production of interleukin-1 receptor antagonist (IL-1Ra) and interleukin-1 beta (IL-1 beta) by peripheral blood mononuclear cells (PBMCs), and compared the effect of first use and reuse of cuprophan membranes on these changes. Studies were performed during dialysis with first use and third reuse of the same kidney. The cell content and production of IL-1Ra and IL-1 beta by unstimulated and endotoxin- or IgG-stimulated PBMCs were studied just prior to dialysis, and from the afferent and efferent limbs of the blood circuit 15 minutes after the start of dialysis. Interleukin-1 receptor antagonist and IL-1 beta were measured by specific radioimmunoassay and are expressed as picograms per 2.5 x 10(6) PBMCs. Fifteen minutes after the start of dialysis, the number of PBMCs harvested from 10 mL of blood decreased from 19.8 +/- 4.7 x 10(6) predialysis to 14 +/- 3 x 10(6) (P = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Gene expression of interleukin-1 beta during hemodialysis

It is still controversial whether the hemodialysis (HD) procedure is an inflammatory process in vivo. Therefore, we studied the gene expression of interleukin-1 beta (IL-1 beta) as a marker of inflammation in peripheral blood mononuclear cells (PBMC) of patients during HD by Northern blotting and polymerase chain reaction. Compared to PBMC separated pre-HD (1.0 densitometric units), the amount of IL-1 beta mRNA was increased in PBMC leaving the dialyzer (12.2 +/- 2 densitometric units, P < 0.01), but was not increased in PBMC re-entering the dialyzer from the systemic circulation (0.6 +/- 0.1 densitometric units) in all 12 patients studied. The maximal amount of IL-1 beta mRNA in PBMC was seen at five minutes after start of HD. There was a significant correlation between the increase in IL-1 beta mRNA and the increase in activated complement C5a (r = 0.71, P < 0.01). HD using less complement-activating membranes (hemophan, polysulfone, polyamide or polyacrylonitrile) resulted in no detectable IL-1 beta mRNA. Furthermore, a monoclonal antibody against human C5a reduced the increase in IL-1 beta mRNA by 83% (P < 0.05), indicating that C5a plays a major role for induction of IL-1 beta mRNA during HD. This study demonstrates that during HD with regenerated cellulose, gene expression for IL-1 beta takes place in PBMC.

Systemic levels of tumor necrosis factor alpha during hemodialysis with cellulosic membranes: no effect of the sterilization procedure

Extractable constituents of dialyzer membranes (e.g., monomers and beta-glucans) may induce the production of cytokines in vitro. We therefore studied circulating tumor necrosis factor alpha (TNF alpha) levels in 23 stable hemodialysis patients during treatment with dry Cuprophan membranes (ETO-sterilized n = 10, steam-sterilized n = 13) longitudinally over a period of 4 weeks. After 4 weeks, those 5 patients of each group showing the highest TNF alpha levels were switched to steam-sterilized, wet Cuprophan membranes. No significant increase in plasma TNF alpha was observed during hemodialysis with either ETO- or steam-sterilized dry Cuprophan membranes. A substantial TNF alpha increase (> or = 100% compared to pre-HD values), however, was observed during 14 of 84 treatment sessions. In 5 selected patients with ETO-sterilized, dry Cuprophan dialyzers, TNF alpha rose from (mean +/- SEM) 17.2 +/- 3.0 (pre-HD) to 20.9 +/- 6.2 (120 min) and 21.9 +/- 4.5 pg/ml (240 min). Corresponding levels in patients with steam-sterilized, dry Cuprophan were 16.2 +/- 5.4 (pre-HD), 21.9 +/- 6.8 (120 min), and 16.0 +/- 3.7 pg/ml (240 min), respectively. There was no difference between ETO- and steam-sterilized dialyzers. No significant reduction in mean TNF alpha plasma levels or in frequency of elevated peak levels was achieved when these patients were switched to wet Cuprophan dialyzers for another 4 weeks. It is suggested that an induction of elevated TNF alpha levels during hemodialysis is possible but is not observed regularly during treatment with Cuprophan membranes.(ABSTRACT TRUNCATED AT 250 WORDS)