Methoxy polyethylene glycol-epoetin beta for anemia with chronic kidney disease

Chronic kidney disease (CKD) is a risk factor for end-stage renal failure and cardiovascular events. In patients with CKD, anemia is often caused by decreased erythropoietin production relative to hemoglobin levels. As correction of anemia is associated with improved cardiac and renal function and quality of life, erythropoiesis-stimulating agents (ESAs) are standard therapy for anemia in CKD patients. However, traditional ESAs such as epoetin or darbepoetin have short half-lives and require frequent administration, dose changes, and close monitoring of hemoglobin concentration to maintain target hemoglobin levels. Methoxy polyethylene glycol-epoetin beta (MPG-EPO) is the only ESA that is generated by chemical modification of glycosylated erythropoietin through the integration of one specific, long, linear chain of polyethylene glycol. This ESA induces continuous erythropoietin receptor activation and has a long half-life (approximately 130 hours). Subcutaneous or intravenous administration of MPG-EPO once every 2 weeks or monthly achieved a high hemoglobin response rate in patients with anemia associated with CKD, regardless of whether the patient was undergoing dialysis. According to data from an observational time and motion study, MPG-EPO maintains hemoglobin levels when the same dose is administered, however infrequently. This suggests that compared with the use of traditional ESAs, administration of MPG-EPO reduces the overall time and cost associated with the management of anemia in CKD patients undergoing dialysis. MPG-EPO is generally well tolerated and most adverse events are of mild to moderate severity. The most commonly reported adverse effects are hypertension, nasopharyngitis, and diarrhea. Subcutaneous injection of MPG-EPO is significantly less painful than subcutaneous injection of darbepoetin. In conclusion, MPG-EPO is as effective and safe as traditional ESAs in managing renal anemia, irrespective of whether the patient is undergoing dialysis

Structural continuity of filtration slit (slit diaphragm) to plasma membrane of podocyte

Structural continuity of filtration slit (slit diaphragm) to plasma membrane of podocyte. Murine monoclonal antibody 5-1-6 was reported to bind to the slit membrane and closely related structures in rat renal glomeruli; it induced heavy, reversible proteinuria and appeared to redistribute onto the plasma membrane of epithelial cells after binding at the original target sites. This phenomenon of antigenic movement has not been analyzed in detail to date. In addition to normal kidneys we also studied localization of the antigen recognized by monoclonal antibody 5-1-6 in protamine sulfate-perfused rat kidneys, in which slit diaphragms are known to be functionally modified. Isolated glomeruli as well as ultrathin kidney cryosections were labeled by the immunogold technique to clarify the relation between this antigen and the slit diaphragm. Sequential localization of injected monoclonal antibody was visualized using a post-embedding immunogold method in rats 2 hours to 12 days after injection of antibody. Ultrastructural immunogold labeling demonstrated that under normal conditions antigenic molecules were expressed mainly in the area beneath the slit diaphragms. Occasionally labeling was found at the base of the foot process, facing the glomerular basement membrane. After protamine sulfate treatment antigenic sites were dislocated due to the lifting and disruption of slit diaphragms, indicating that this antigen is associated with slit diaphragms. Injected antibody was localized at the filtration slits at 2 hours, and by 12 hours it had moved onto the apical plasma cell membrane of foot process. In addition, from 3 days onwards patch or cap-like formation on the plasma cell membrane of podocytes was seen. Possible shedding of antibody from podocyte cell surface membrane was occasionally encountered, but internalization of antibody was a minor event. Elution experiments in isolated glomeruli at day 3 indicated that antigen and antibody were both localized on the podocyte cell surface membrane, suggesting redistribution of immune complexes. In conclusion, filtration slits (slit diaphragms) and the apical membrane of foot process of podocytes demonstrate structural continuity, as revealed by the movement of the antigen recognized by monoclonal antibody 5-1-6 as antigen-antibody complexes