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Copenhagen, Denmark

Krzystanek M.,KB3011 | Pedersen T.X.,KB3011 | Pedersen T.X.,Copenhagen University | Bartels E.D.,KB3011 | And 4 more authors.
Journal of Biological Chemistry | Year: 2010

The ability to produce apolipoprotein (apo) B-containing lipoproteins enables hepatocytes, enterocytes, and cardiomyocytes to export triglycerides. In this study, we examined secretion of apoB-containing lipoproteins from mouse kidney and its putative impact on triglyceride accumulation in the tubular epithelium. Mouse kidney expressed both the apoB and microsomal triglyceride transfer protein genes, which permit lipoprotein formation. To examine de novo lipoprotein secretion, kidneys from human apoB-transgenic mice were minced and placed in medium with 35S-amino acids. Upon sucrose gradient ultracentrifugation of the labeled medium, fractions were analyzed by apoB immunoprecipitation. 35S-Labeled apoB100 was recovered in ∼1.03-1.04 g/ml lipoproteins (i.e. similar to the density of plasma low density lipoproteins). Immunohistochemistry of kidney sections suggested that apoB mainly is produced by tubular epithelial cells. ApoB expression in the kidney cortex was reduced ∼90% in vivo by treating wild type mice with apoBantisense locked nucleic acid oligonucleotide. Inhibition of apoB expression increased fasting-induced triglyceride accumulation in the kidney cortex by 20-25% (p = 0.008). Cholesterol stores were unaffected. Treatment with control oligonucleotides with 1 or 4 mismatching base pairs affected neither the triglyceride nor the cholesterol content of the kidney cortex. The results suggest that mammalian kidney secretes apoB100-containing lipoproteins. One biological effect may be to dampen excess storage of triglycerides in proximal tubule cells. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.

Pedersen T.X.,KB3011 | Pedersen T.X.,Copenhagen University | Binder C.J.,Austrian Academy of Sciences | Binder C.J.,Medical University of Vienna | And 5 more authors.
Nephrology Dialysis Transplantation | Year: 2010

Background. Uraemia increases oxidative stress, plasma titres of antibodies recognizing oxidized low-density lipoprotein (oxLDL) and development of atherosclerosis. Immunization with oxLDL prevents classical, non-uraemic atherosclerosis. We have investigated whether immunization with oxLDL might also prevent uraemia-induced atherosclerosis in apolipoprotein E knockout (apoE-/-) mice.Methods. ApoE-/- mice were immunized with either native LDL (n = 25), Cu2+-oxidized LDL (n = 25), PBS (n = 25), the apolipoprotein B-derived peptide P45 (apoB-peptide P45) conjugated to bovine serum albumin (BSA) (n = 25) or BSA (n = 25) prior to induction of uraemia by 5/6 nephrectomy (NX).Results. Immunization with oxLDL increased plasma titres of immunoglobulin G (IgG) recognizing Cu2+-oxLDL and malondialdehyde-modified LDL (MDA-LDL). However, 5/6 NX induced a marked increase in plasma concentrations of anti-oxLDL antibodies as well as pro-atherogenic cytokines [interleukin (IL)-2 (IL-2), IL-4, IL-6 and IL-12)] in native mouse LDL (nLDL)-, oxLDL- and PBS-immunized mice. Even though nLDL- and oxLDL-immunized mice displayed higher anti-MDA-LDL IgG titres than the PBS group, aortic atherosclerosis lesion size was not affected by immunization. Immunization with the apoB-peptide P45, which consistently reduces classical atherosclerosis in non-uraemic mice, also did not reduce lesion size in uraemic apoE-/- mice.Conclusion. The results suggest that the pro-inflammatory and pro-atherogenic effect of uraemia overrules the anti-atherogenic potential of oxLDL immunization in apoE-/- mice. © The Author [2009]. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

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