Complement-dependent acceleration of apoptosis in neutrophils by dialyzer membranes

Reduction in the presence of cryoglobulins over time in the hemodialysis treatment

BACKGROUND

The presence of cryoglobulins in patients with chronic kidney disease (CKD) on hemodialysis is well described. However, the generation of cryoglobulins during the dialysis treatment has yet to be established. The aim of the present study was to determine the presence of serum cryoglobulins over time in the dialysis treatment in patients with CKD not infected with hepatitis C virus (HCV).

METHOD

Peripheral blood samples were collected at the beginning of dialysis treatment and at 30, 60, 90 and 120 days afterwards. Cryoglobulins were defined by the presence of immunocomplexes that precipitated in vitro with exposure to cold and resolubilized when rewarmed. The components of the cryoprecipitate were analyzed by radial immunodiffusion.

RESULTS

In this study, 14 patients were included: 11 male and three female, aged 28-88 years, with mean time on hemodialysis of 57 ± 36 days at baseline. The presence of cryoglobulin, constituted by IgM, IgA, IgG and the C3 and C4 components of the complement, was observed in the serum of all patients at the beginning of hemodialysis. Sequence analyses showed that the amount of cryoprecipitate decreased during the dialysis treatment.

CONCLUSION

There was a high prevalence of mixed cryoglobulins in CKD patients at the beginning of hemodialysis, and the amount of cryoprecipitate decreased during the treatment.

Neutrophil apoptosis: impact of granulocyte macrophage colony stimulating factor on cell survival and viability in chronic kidney disease and hemodialysis patients

INTRODUCTION

Altered neutrophil apoptosis might be responsible for recurrent bacterial infections encountered in hemodialysis (HD) and chronic kidney disease (CKD) patients. This work was designed to assess the neutrophil apoptotic activity and the impact of implementation of granulocyte macrophage colony stimulating factor (GM-CSF), as a survival factor, on neutrophil apoptosis among these patients.

MATERIAL AND METHODS

Twenty-five patients on regular HD along with 34 CKD patients on conservative treatment, as well as 15 healthy controls, were investigated for apoptotic rate via assessment of neutrophil expression of Annexin-V by flow cytometry, before and after 20 h culture in absence and presence of GM-CSF. Neutrophil viability was determined using light microscopy. The preservation of neutrophil activation in these patients was analyzed by flow cytometric CD18 neutrophil expression. Chronic inflammatory state was evaluated by estimating C-reactive protein (CRP) and soluble intercellular adhesion molecule-1 (sICAM-1). Obtained data were statistically analyzed.

RESULTS

Compared to controls, both HD and CKD groups had a significant increase of Annexin-V and CD18 expression and significant decrease in neutrophil viability. Culture of their neutrophils with GM-CSF showed significant decrease of apoptosis accompanied by improvement of neutrophil viability compared to their cultured cells without GM-CSF. These patients also showed significant elevation of CRP and sICAM-1.

CONCLUSIONS

Granulocyte macrophage colony stimulating factor demonstrated an evident impact on improving in vitro neutrophil survival and viability in HD and CKD patients. Therefore, this may represent promising preventive and/or therapeutic strategies against infection frequently observed in these patients and causing morbidity and mortality.

RENAL RESEARCH INSTITUTE SYMPOSIUM: Longitudinal Study of Apoptosis in Chronic Uremic Patients

Uremia is associated with a state of immune dysfunction, increasing infection and malignancy rates. Dysregulation of homeostasis may be directly related to abnormal apoptosis regulation, a process which is crucial for the maintenance of the biologic system. Abnormal apoptosis rates (ARs) have been reported in the literature. We performed a longitudinal study over a 10-week period in three groups of uremic subjects-hemodialysis (HD), peritoneal dialysis (PD), and predialysis chronic renal failure (CRF). Our results showed that ARs were consistent over the observed period. Monocytes extracted from HD and CRF subjects had higher ARs compared to PD and controls (HD: 26.06 +/- 8.82; CRF: 26.96 +/- 12.81; PD: 14.77 +/- 5.87; C: 11.42 +/- 4.60) when placed in culture medium. The plasma of HD and CRF subjects when incubated with U937 cells had a stronger apoptogenic potential compared with PD and controls (HD: 26.08 +/- 11.39; CRF: 24.87 +/- 9.07; PD: 12.13 +/- 4.51; C: 11.69 +/- 4.02). Inflammatory markers (C-reactive protein [CRP], procalcitonin) and cytokines (interleukin [IL]-1beta, IL-2, IL-10) had a generally poor correlation except for tumor necrosis factor (TNF)-alpha (p < 0.001). The phagocytic ability of U937 cells when incubated with the various plasma demonstrated impaired response in the HD and CRF subjects (HD: 27.56 +/- 6.67; CRF: 30.24 +/- 9.08; PD: 36.55 +/- 9.80; C: 40.04 +/- 6.98). These results suggest continuous renal purification, such as in continuous ambulatory peritoneal dialysis (CAPD), may have advantages over intermittent therapies in regulating apoptosis and maintaining biologic function and homeostasis.