Identification of target antigens of antiendothelial cell antibodies in healthy individuals: A proteomic approach.
ABSTRACT In order to identify target antigens of anti-endothelial cell (anti-EC) antibodies (AECA) in healthy individuals, we have used a proteomic approach combining 2-DE and immunoblotting. Whole cell protein extracts obtained from human umbilical vein EC (HUVEC) cultures were used as a source of antigens. Serum IgG from 12 healthy blood donors were tested at a concentration of 200 microg/mL. Targeted spots were identified by MS. The HUVEC proteome was composed of 884 protein spots. Among these, 61 +/- 25.8 (mean +/- SD) spots were recognized by serum IgG from healthy individuals, with marked differences from one individual to another. Among these spots, 11 were recognized by serum IgG from all healthy individuals tested. These spots corresponded to six different proteins with several spots corresponding to different isoforms of the same protein. Target antigens were: cytoskeletal proteins (beta-actin, alpha-tubulin, and vimentin); glycolytic enzymes (glucose-3-phosphate-deshydrogenase and alpha-enolase); and prolyl-4-hydroxylase beta subunit, a member of the disulfide isomerase family. This study shows that the repertoire of IgG AECA is heterogeneous among healthy individuals. IgG from all of the healthy individuals tested recognized a restricted set of highly conserved ubiquitous proteins playing key roles in cell biology and maintenance of homeostasis.
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ABSTRACT: Hepatoportal sclerosis accompanied by dense elastic fibre deposition is generally regarded as the primary lesion in the development of idiopathic portal hypertension (IPH). This study was performed to clarify the mechanism of elastic fibre deposition in the peripheral portal tracts of IPH liver in relation to serum anti-endothelial cell antibodies (AECA). In-vitro experiments were performed using human dermal microvascular endothelial cells (HMVEC) and patients' sera. The presence of serum AECA was assayed by a cell-based enzyme-linked immunosorbent assay (ELISA) using HMVEC. Immunohistochemical analysis of elastin was performed using liver tissue sections of IPH patients. IPH sera contained one or more AECA that could bind to the vascular endothelial cells of the peripheral portal tracts of the liver. When the value of AECA greater than the mean ± 2 standard deviations of healthy controls was regarded as positive, the positive detection rate of either immunoglobulin (Ig)G, IgA or IgM AECA in IPH sera was 30% (10 of 33 cases). IPH sera induced the expression of elastin in HMVEC, which appeared to be associated with the presence of AECA. Apoptosis was also induced in HMVEC by the stimulation with IPH sera. In vivo, elastin expression was observed in the endothelial cells of the peripheral portal tracts of IPH livers in a proportion of cases. The disease pathogenesis of IPH seems to be heterogeneous, and this study elucidated a possible contribution of the induction of elastin expression in the portal vessels to hepatoportal sclerosis of IPH, which might be linked to serum AECA as a causative factor.Clinical & Experimental Immunology 03/2012; 167(3):532-42. · 3.41 Impact Factor
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ABSTRACT: Over the past few years, considerable advances have been made in our understanding of the molecular pathomechanisms of human membranous nephropathy, inspired by studies of Heymann nephritis, a faithful experimental model of this disease. This research led to the identification of neutral endopeptidase, the M-type receptor for secretory phospholipase A(2) (PLA(2)R1) and cationic bovine serum albumin as target antigens of circulating and deposited antibodies in alloimmune neonatal, adult 'idiopathic' and early-childhood membranous nephropathy, respectively. A genome-wide association study has provided further evidence for a highly significant association between PLA2R1 and HLA-DQA1 loci and idiopathic membranous nephropathy in patients of white ancestry. Additional antibody specificities for cytoplasmic antigens have also been identified, but their pathogenic role is uncertain. The time has come to revisit the spectrum of membranous nephropathies based on the newly identified antigen-antibody systems that should be considered as molecular signatures of the disease and that challenge the uniform histological definition. These signatures will soon have a major impact on patient care.Nature Reviews Nephrology 02/2012; 8(4):203-13. · 7.94 Impact Factor
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ABSTRACT: Profiling the autoantibody repertoire with proteome-wide antigen collections is emerging as a powerful tool for the identification of biomarkers for autoimmune diseases. Here, a systematic and undirected approach was taken to screen for profiles of IgG in human plasma from 90 individuals with multiple sclerosis (MS) related diagnoses. Reactivity pattern of 11,520 antigens (corresponding to ~38% of all human protein encoding genes) were generated on planar protein microarrays built within the Human Protein Atlas. IgG reactivity was observed towards more than 2,000 antigens, among which 64% were recognized only in single individuals. Reactivity distributions among MS subgroups were used to select 384 antigens, which were then re-evaluated on planar microarrays, corroborated with suspension bead arrays in a larger cohort (n=376), and confirmed for specificity in inhibition assays. Among the heterogeneous pattern within and across MS subtypes, differences in recognition frequencies were found for 51 antigens, which were enriched for proteins of transcriptional regulation. In conclusion, a strategy on complementary high-throughput protein array platforms facilitated the discovery and verification of disease-associated autoimmunity signatures that are proposed as additional antigens for larger scaled validation across MS biobanks.Molecular & Cellular Proteomics 06/2013; · 7.25 Impact Factor