title: Apolipoproteins prevent glomerular albumin permeability induced in vitro by serum from patients with focal segmental glomerulosclerosis.
abstract: Glomerular albumin permeability alterations can be induced in vitro by serum from patients with end-stage renal disease caused by primary focal segmental glomerulosclerosis (FSGS). It was hypothesized that inhibitory substances may be present in normal serum, which may prevent the permeability alterations in isolated glomeruli, and the present study sought to isolate and characterize these factors. Albumin permeability was determined from the change in glomerular volume induced by applying oncotic gradients across the basement membrane of healthy isolated rat glomeruli preincubated with FSGS serum and normal serum fractionated using standard techniques. Fractions of normal serum with inhibitory activity obtained by a multistep chromatographic procedure underwent two-dimensional electrophoresis and staining. Approximately 50 protein spots were recovered, renatured, and tested for antipermeability activity. Five of these proteins demonstrated consistent inhibitory activity, and desorption ionization and mass spectrometry proved them to be components of high-density lipoprotein: apolipoproteins (apo) E(2) and E(4), high-molecular-weight J and L, and a 28-kD fragment of A-IV. Polyclonal antibodies to apo E or apo J added to the whole normal serum restored the permeability activity of the FSGS serum in the bioassay. Commercially available apo E and apo J also demonstrated antipermeability activity when added to FSGS serum. Cyanogen bromide digestion of apo A-IV produced fragments that inhibited the permeability activity of the FSGS serum, whereas the intact protein did not. Thus, components of high-density lipoprotein are capable of preventing glomerular albumin permeability induced by serum from patients with FSGS in an in vitro system. The specificity and mechanism of the inhibition remain to be determined; the alteration of normal inhibitory activity in vivo may be a component in the pathophysiology of FSGS.
authors.affiliation: Unit and Laboratory of Nephrology, Istituto G. Gaslini, Genoa, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Candiano
authors.affiliation: Unit and Laboratory of Nephrology, Istituto G. Gaslini, Genoa, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Musante
authors.affiliation: Istituto di Medicina Clinica, University of Trieste, Trieste, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Carraro
authors.affiliation: Istituto di Medicina Clinica, University of Trieste, Trieste, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Faccini
authors.affiliation: Istituto di Medicina Clinica, University of Trieste, Trieste, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Campanacci
authors.affiliation: Istituto di Medicina Clinica, University of Trieste, Trieste, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Zennaro
authors.affiliation: Istituto di Medicina Clinica, University of Trieste, Trieste, Italy.
authors.forename: Mary
authors.initials: M
authors.lastname: Artero
authors.affiliation: Unit and Laboratory of Nephrology, Istituto G. Gaslini, Genoa, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Ginevri
authors.affiliation: Unit and Laboratory of Nephrology, Istituto G. Gaslini, Genoa, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Perfumo
authors.affiliation: Unit and Laboratory of Nephrology, Istituto G. Gaslini, Genoa, Italy.
authors.forename: Rosanna
authors.initials: R
authors.lastname: Gusmano
authors.affiliation: Unit and Laboratory of Nephrology, Istituto G. Gaslini, Genoa, Italy.
authors.forename: Gian Marco
authors.initials: GM
authors.lastname: Ghiggeri
mesh_terms: D000418:Albumins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000906:Antibodies / Q000494:pharmacology; D001053:Apolipoproteins / Q000037:antagonists & inhibitors / Q000097:blood* / Q000737:chemistry; D002648:Child; D002675:Child, Preschool; D005260:Female; D005923:Glomerulosclerosis, Focal Segmental / Q000097:blood* / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007678:Kidney Glomerulus / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010539:Permeability
chemical_list: D000418:Albumins; D000906:Antibodies; D001053:Apolipoproteins; D010446:Peptide Fragments