ABSTRACT
BACKGROUND: Aberrant glomerular polyanionic charge of glycosaminoglycans (GAGs) and sialic acid expression has been observed in proteinuric human and experimental glomerular diseases. Angiotensin-converting enzyme inhibitors (ACEI) lower proteinuria and amend renal function deterioration via hemodynamic mechanisms. We tested the hypothesis that ACEI modulate proteinuria additionally by modifying glomerular GAGs. METHODS: In this study, we explored the effects of the ACEI enalapril on proteinuria and GAG synthesis in puromycin aminonucleoside (PAN)-treated rats. We employed cationic colloidal gold (CCG) localization in glomerular basement membranes (GBM) to identify GAGs by electron microscopy and determined sialic acid residues by immunohistochemical staining with lectins. To clarify ACEI effects on GAG production in vitro, we studied de novo GAG synthesis into newly synthesized proteoglycans in podocytes and mesangial cells using 35S incorporation. Cells were incubated with or without PAN, and with increasing doses of the ACEI enalaprilat. RESULTS: PAN rats developed severe proteinuria that was significantly improved by enalapril treatment. In non-treated PAN rats GBM GAGs were reduced, whereas in the enalapril-treated group GBM GAGs were significantly increased to control levels. Enalapril did not affect glomerular sialic acid. Furthermore, in cultured podocytes and mesangial cells PAN decreased de novo GAG synthesis, an effect which was significantly ameliorated by enalaprilat treatment. CONCLUSION: Treatment with ACEI improves permselectivity properties of the glomerular capillary wall by maintaining its GAG content. This finding provides an additional new mechanism, whereby ACEI exert anti-proteinuric effects.
Subject(s)
Angiotensin-Converting Enzyme Inhibitors/pharmacology , Enalapril/pharmacology , Glycosaminoglycans/biosynthesis , Kidney Glomerulus/drug effects , Nephrosis/metabolism , Puromycin Aminonucleoside/toxicity , Animals , Disease Models, Animal , Immunohistochemistry , Kidney Glomerulus/metabolism , Kidney Glomerulus/ultrastructure , Male , Microscopy, Electron, Transmission , Nephrosis/pathology , Podocytes/drug effects , Protein Synthesis Inhibitors/toxicity , Rats , Rats, WistarABSTRACT
Shortage in tissue availability from cadaver donors and the need for life-long immunosuppression severely restrict the large-scale application of cell-replacement therapy for diabetic patients. This study suggests the potential use of adult human liver as alternate tissue for autologous beta-cell-replacement therapy. By using pancreatic and duodenal homeobox gene 1 (PDX-1) and soluble factors, we induced a comprehensive developmental shift of adult human liver cells into functional insulin-producing cells. PDX-1-treated human liver cells express insulin, store it in defined granules, and secrete the hormone in a glucose-regulated manner. When transplanted under the renal capsule of diabetic, immunodeficient mice, the cells ameliorated hyperglycemia for prolonged periods of time. Inducing developmental redirection of adult liver offers the potential of a cell-replacement therapy for diabetics by allowing the patient to be the donor of his own insulin-producing tissue.
Subject(s)
Cell Differentiation , Diabetes Mellitus, Type 1/therapy , Genetic Engineering , Genetic Therapy/methods , Hepatocytes/cytology , Homeodomain Proteins/genetics , Islets of Langerhans/cytology , Trans-Activators/genetics , Adenoviridae , Animals , Cells, Cultured , DNA Primers , Enzyme-Linked Immunosorbent Assay , Fluorescent Antibody Technique , Glucose/metabolism , Hepatocytes/transplantation , Hepatocytes/ultrastructure , Humans , Immunohistochemistry , Insulin/metabolism , Male , Mice , Mice, Inbred NOD , Mice, SCID , Microscopy, Electron , Reverse Transcriptase Polymerase Chain Reaction , Transduction, Genetic/methodsABSTRACT
In view of the constant increase in the aged population, age-adjusted cancer therapy becomes an urgent target. Although cancer incidence rises with age, paradoxically, growth rate and metastasis often proceed at a slower rate in the aged. Determining the mechanism(s) underlying this reduced tumor progression in the old might have implications for a rational design of age-adjusted therapy. Thus far, decreased cell proliferation or immune response modifications were suggested as possible mechanisms. We show here that an increased tendency to apoptotic tumor cell death in the aged could constitute an additional mechanism. Based on this mechanism, we compared the therapeutic efficacy of two apoptosis inducers, hydrocortisone and adriamycin, on AKR lymphoma and B16 melanoma growth in young and old mice. Treatment with hydrocortisone acetate inhibited tumor growth practically only in old mice in the two tumor systems. Similar effects were obtained with adriamycin treatment of AKR lymphoma but opposite results were seen with B16 melanoma. We thus demonstrated, in three of the four tumor-therapeutic modality systems examined, an age-related antitumoral efficacy of two apoptosis-inducing agents, with tendency for a remarkably more pronounced effect in aged mice.
