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.

Interleukin-6, interleukin-8 and monocyte chemotactic peptide-1 gene expression and protein synthesis are independently modulated by hemodialysis membranes.

BACKGROUND: Uremia produces a wide range of abnormalities of the immune system. Blood-membrane interaction in hemodialysis results in activation and severe dysfunction of peripheral blood mononuclear cells (PBMC). However, the question of whether the use of different dialytic membranes may improve PBMC dysfunctions remains unanswered. METHODS: To address this issue, the spontaneous interleukin (IL)-6, IL-8 and monocyte chemotactic peptide-1 (MCP-1) gene expression and protein release were studied in PBMC isolated from 7 healthy subjects, 8 uremic patients on conservative therapy and 8 uremic patients undergoing subsequent one month periods of hemodialysis with cuprophan (CU) and high-flux noncomplement activating membranes, polymethylmethacrylate (PMMA) and polyamide (PA). At the end of each period of treatment, PBMC were harvested at the beginning (T0) and after 180 minutes of dialysis (T180), and then were cultured in complete medium. IL-6, IL-8 and MCP-1 mRNA expression were studied by RT-PCR. In addition, MCP-1 gene expression was evaluated also by in situ hybridization. Cytokines released in the supernatant were measured by ELISA. RESULTS: Compared to the control group, PBMC from uremic patients on conservative therapy and treated by CU showed a clear reduction in the cytokine release, while PMMA and PA membranes were able to normalize IL-6, IL-8 and MCP-1 protein concentration, which had been reduced by CU treatment. Interestingly, at T0, mRNA expression for all three cytokines was increased in the patients treated by CU, when compared to the control group and the uremic patients on conservative therapy. A further up-regulation was observed at T180. PMMA and PA treatment, despite increasing the cytokine secretion, significantly reduced the dialysis-induced cytokine gene expression. CONCLUSION: PBMC exposure to CU membranes results in cytokine mRNA overexpression associated with a paradoxically reduced protein release. In contrast, long-term hemodialysis with synthetic high-flux membranes reduces IL-6, IL-8 and MCP-1 gene expression and improves the ability of PBMC to secrete these cytokines. The reduced cytokine secretion during bioincompatible dialysis may reflect a PBMC adaptation that protects uremic patients against the inflammatory effects of persistent cytokine release.

[DRG's and cost/efficacy indicators in nephrology and dialysis. Results at a hospital division]. / DRG e indicatori di costo/efficacia in nefrologia e dialisi. Risultati in una Divisione ospedaliera.

The Diagnosis Related Groups (DRGs) classification system correlates hospital performance with their relative costs and encourages more efficient productive processes. We report the following parameters: a) the distribution of hospital discharges according to the Major Diagnostic Categories (MDCs) and DRGs; b) the relationship between mean length of stay and threshold values; c) economic analysis of the cost-reimbursement pay-off. The results showed that 71.3% of DRGs belonged to nephro-urological MDC 11 and 28.7% in other internal MDCs (mainly involving cardiac and respiratory system). Of the latter, 67.7% were utilized for dialysis and transplant patients and kidney donors. In MDC 11 the most common DRGs were: the surgical DRG 315, produced by the vascular accesses for hemodialysis and by insertion of Tenckoff catheter for peritoneal dialysis, DRG 316 by cases of acute and chronic renal failure, DRG 332 by biopsy-proven glomerulonephritides. The length of stay was most commonly within range of one-third of threshold value for specific DRG; there was a low percentage of one-day stays and outlier cases. The economic analysis demonstrated that mean daily reimbursement sum was 590,714 ITL. Analysis of the overall costs yielded a mean daily cost of 455,838 ITL. In conclusion, quality indicators show that, appropriately, our specialist activity is largely devoted to the diagnosis and treatment of acute and chronic nephropathies and complications following dialysis and renal transplant.

Endotoxins modulate chronically tumour necrosis factor alpha and interleukin 6 release by uraemic monocytes.

We examined in vivo the release of tumour necrosis factor alpha (TNF alpha) and interleukin 6 (IL-6) by uraemic monocytes upon stimulation with endotoxin-contaminated bicarbonate concentrate. Twelve uraemic patients underwent 1-month-subsequent periods of standard haemodialysis (SHD) with cuprophane (CU), a high-complement-activating membrane (6 patients), or haemodiafiltration (HDF) with polyacrylonitrile (PAN), a low-complement-activating membrane (6 patients), by using a dialysate prepared with either non-sterile bicarbonate concentrate tanks (phase 1) or sterile bicarbonate concentrate bags (phase 2). TNF alpha and IL-6 concentrations were determined in monocyte supernatants by ELISA; endotoxin levels in bicarbonate concentrates were measured by a chromogenic limulus amoebocyte lysate (LAL) assay. A significant increase in LAL reactivity was found in bicarbonate concentrate tanks compared to sterile bags (P < 0.001). Non-sterile dialysate caused a significant (P < 0.001) predialytic increase in monocyte TNF alpha release as compared to controls and non-dialysed uraemic patients. One month treatment with sterile bicarbonate significantly decreased TNF alpha predialytic activity in monocyte supernatants (P < 0.001) to levels closer to those of non-dialysed uraemic patients. A similar decrease was observed for IL-6 production. Dialytic treatment induced a further increase in both TNF alpha and IL-6 production, particularly in phase 1.(ABSTRACT TRUNCATED AT 250 WORDS)

C5b-9 generation and cytokine production in hemodialyzed patients.

The role of the complement system in the induction of cytokine release is controversial. Plasma terminal C complex C5b-9 along with Bb and C4d fragments were evaluated in 22 patients during routine acetate or bicarbonate hemodialysis using cuprophane membranes and hemodiafiltration (HDF) or acetate-free-biofiltration (AFB) using polyacrylonitrile (PAN) membranes. In a subgroup of six uremic patients we also evaluated the release of tumor necrosis factor (TNF alpha) and interleukin-6 (IL-6) from monocytes before and after six subsequent sessions with bicarbonate-cuprophane, HDF and AFB-PAN. At beginning of the dialysis increased plasma C5b-9 levels were found in patients treated by acetate or bicarbonate-cuprophane. Moreover, a rapid significant (P < 0.001) increase of C5b-9 levels occurred in both groups 15 minutes after the onset of the hemodialysis procedure with a plateau at 180 minutes. In contrast, only a slight increase in the plasma C5b-9 levels was observed in patients dialysed with HDF or AFB using PAN membranes. This increase was more pronounced with HDF at 0 minutes compared with controls. A positive linear correlation was found in all patients between C5b-9 generation and plasma Bb levels at different times in the dialysis session. The production of C4d fragment remained unchanged in all groups, indicating that C5b-9 complex generation is due to the prevalent alternative complement pathway activation. The pattern of cytokine production strictly resembled the complement system activation and C5b-9 generation.(ABSTRACT TRUNCATED AT 250 WORDS)

Involvement of peripheral blood monocytes in haemodialysis: in vivo induction of tumour necrosis factor alpha, interleukin 6 and beta 2-microglobulin.

Our aim was to evaluate the role of three different variables in the activation of the monocyte system: dialysis membrane (cuprophane or polyacrylonitrile), dialysate (acetate or bicarbonate), and procedure (standard or high-flux haemodialysis). By ELISA test we measured the 'in vivo' intracellular (monocyte-associated) production and extracellular release of tumour necrosis factor alpha (TNF alpha), interleukin-6 (Il-6) and beta 2-microglobulin (beta 2-M) by monocytes from 20 uraemic patients before and after the dialysis session. At the beginning of the dialysis session, uraemic patients' cultured monocytes spontaneously released a greater amount of TNF alpha, Il-6 and beta 2-M compared to normal controls. However, no differences in cytokine and beta 2-M were observed in monocyte lysate between the two groups. At the end of the dialysis session, cultured monocytes from patients treated with cellulosic membranes and acetate dialysate showed greater TNF alpha values than normal controls (P less than 0.001 and P less than 0.05 respectively). Moreover, TNF alpha and Il-6 values were strictly correlated (P less than 0.05). These results clearly show an activation of the monocyte system in uraemic patients undergoing periodic haemodialysis. The implicated factors may be multiple, such as complement activating cellulosic membranes or acetate dialysate. The production of TNF alpha, Il-6 and beta 2-M may explain some of the pathological findings observed in long-term haemodialysis patients.

Circulating immune complexes in HBsAg-positive and HBsAg-negative chronic liver diseases.

Circulating immune complexes (CIC) were investigated by the fluid-phase C1q-binding test in serum samples from 131 subjects with various clinical types of HBsAg-positive and HBsAg-negative chronic hepatitis diagnosed on both clinical and laboratory criteria, including liver biopsy; serum samples from 28 asymptomatic HBsAg carriers and 75 healthy controls were also examined. The results of these findings were correlated with the liver damage and the clinical course of the disease. CIC were detected in all categories of chronic hepatitis with a significant prevalence only in patients with liver cirrhosis. No correlation was found between the levels of CIC, the presence of circulating HBsAg, and active inflammation or necrosis in any of the different types of chronic hepatitis. In contrast, a highly significant correlation was found between the prevalence of CIC and a more severe prognosis in patients with CAH and liver cirrhosis. The findings suggest that the presence of CIC is not specific for a given type of chronic liver disease and that they do not play any role in the pathogenesis of liver damage. The correlation observed between the presence of CIC and an unfavourable course of chronic liver disease suggests that CIC may modify the host's immune defence mechanisms.