| 1. |
- Bolton, W K, et al.
(författare)
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Epitope spreading and autoimmune glomerulonephritis in rats induced by a T cell epitope of Goodpasture's antigen
- 2005
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Ingår i: Journal of the American Society of Nephrology. - 1046-6673. ; 16:9, s. 2657-2666
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Tidskriftsartikel (refereegranskat)abstract
- An amino-terminal region of a, chain of type IV collagen noncollagenous domain [alpha(3)(IV)NC1] that induces experimental autoimmune glomerulortephritis (EAG) in rats has been identified. Only recombinant antigens that contain a nine-amino acid (AA) span of alpha(3)(IV)NC1, consistent with a T cell epitope, could induce EAG. It was hypothesized that synthetic peptides of this region should induce EAG. Human and rat peptides of this region were synthesized and rats were immunized to define the nephritogenic epitope. A 13-AA rat peptide induced EAG with proteinuria, decreased renal function, and glomerular basement membrane (GBM)-bound deposits in half of the rats. This peptide induces lymph node cell proliferation and development of antibodies to epitopes of alpha(3)(IV)NC1 external to the peptide immunogen. Carboxy-terminal extension to 21 amino acids results in all rats' demonstrating anti-GBM antibody and severe EAG. Asparagine at position 19 is critical for EAG induction. None of the 50 rats that were immunized with peptide that contained human sequence with isoleucine at position 19 developed EAG, whereas rat sequence with asparagine 19 induced EAG. Truncation of amino terminal AA of the peptide aborts EAG induction. These studies demonstrate that a T cell epitope of alpha(3)(IV)NC1 induces lymph node cell proliferation, EAG, and intramolecular epitope spreading; that the length of this peptide influences the formation of anti-GBM antibody; and that the presence of asparagine at position 19 of the peptide is critical to disease induction.
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| 2. |
- Chen, Lanlin, et al.
(författare)
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A nephritogenic peptide induces intermolecular epitope spreading on collagen IV in experimental autoimmune glomerulonephritis
- 2006
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Ingår i: Journal of the American Society of Nephrology. - 1046-6673. ; 17:11, s. 3076-3081
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Tidskriftsartikel (refereegranskat)abstract
- This group previously identified a peptide p13 of alpha 3(IV)NC1 domain of type IV collagen that induces experimental autoimmune glomerulonephritis (EAG) in rats with generation of antibodies to sites on alpha 3(IV)NC1 external to the peptide as a result of intramolecular epitope spreading. It was hypothesized that intermolecular epitope spreading to other collagen IV chains also was induced. Rats were immunized with nephritogenic peptide that was derived from the amino terminal part of rat alpha 3(IV)NC1 domain, and serum and kidney eluate were examined for antibodies to both native and recombinant NC1 domains of collagen IV. Peptide induced EAG with proteinuria and decreased renal function and glomerular basement membrane IgG deposits. Sera from these rats were examined by ELISA, which revealed reactivity not only to immunizing peptide but also to human and rat alpha 3(IV)NC1 and to human alpha 4(IV)NC1 domains. Kidney eluate that was depleted of alpha 3(IV)NC1 antibodies still reacted to alpha 4(IV)NC1, and alpha 3(IV)NC1 column-bound antibody reacted with alpha 3(IV)NC1. There was minimal reactivity to other collagen chains. Eluate that was adsorbed to NC1 hexamer from rat glonterular basement membrane lost all reactivity to glomerular constituents, and the eluted antibodies reacted to alpha 3(IV)NC1 and alpha 4(IV)NC1 domains. These studies show that a T cell epitope of alpha 3(IV)NC1 induces EAG, intramolecular epitope spreading along alpha 3(IV)NC1, and intermolecular epitope spreading to alpha 4(IV)NC1 domain with minimal or no reactivity to other collagen chains or glomerular constituents. This is the first demonstration in EAG of intermolecular epitope spreading and identification of the spread epitopes.
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| 3. |
- Hellmark, Thomas, et al.
(författare)
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Comparison of anti-GBM antibodies in sera with or without ANCA
- 1997
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Ingår i: Journal of the American Society of Nephrology. - 1046-6673. ; 8:3, s. 376-385
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Tidskriftsartikel (refereegranskat)abstract
- An appreciable percentage of patients with serum anti-glomerular basement membrane (anti-GBM) antibodies also have antineutrophil cytoplasmic antibodies (ANCA), against either myeloperoxidase (MPO-ANCA), or proteinase 3 (PR3-ANCA). In sera without ANCA, the anti-GBM antibodies have been shown to react mainly with the noncollagenous domain (NC1) of Type IV collagen, and especially with its alpha 3 chain, alpha 3(IV)NC1. In most sera, the antibodies can be partially blocked by a monoclonal antibody (Mab17) against alpha 3(IV)NC1, suggesting that a limited region is recognized. Although there is evidence that some anti-GBM antibodies that coexist with ANCA react with alpha 3(IV)NC1, extensive analysis of the specificity of such anti-GBM antibodies has not been reported. In the study presented here, sera were analyzed from 332 patients tested both for anti-GBM antibodies and ANCA (MPO or PR3-ANCA) and found to have one or more positive tests. Of the 100 sera with anti-GBM antibodies, 38 also had ANCA-25 with MPO-ANCA (66%), 12 with PR3-ANCA (32%), and one with both (2%). Of the 232 sera with ANCA only, 153 had MPO-ANCA (66%), 75 had PR3-ANCA (32%), and four had both (2%). Sera was also analyzed from 259 other patients who had positive ANCA tests and were not tested for anti-GBM antibodies: 138 had MPO-ANCA (54%), and 121 had PR3-ANCA (46%). The relative frequencies of MPO or PR3-ANCA in patients with coexisting anti-GBM antibodies did not differ significantly from those in all patients with ANCA (P = 0.35). Seventeen sera with anti-GBM antibodies only and 16 sera with anti-GBM antibodies plus ANCA were selected for further studies to compare the specificity of anti-GBM antibodies in sera with or without ANCA. Using enzyme-linked immunosorbent assays (ELISA), all sera in both groups were found to react with the NC1 domain (as a hexamer) of bovine Type IV collagen and with alpha 3 (IV)NC1 monomers. Furthermore, all but six sera also reacted with one or more of the alpha 1, 2, and 4 (IV)NC1 monomers, generally with considerably lower titers. Reactivity to alpha 3(IV)NC1 was partially blocked by Mab17, with comparable degrees of inhibition in both groups. Western blot analysis with the human NC1 domains revealed no differences in reactivity between the two groups. Thus, differences in antigen specificities of anti-GBM antibodies in sera with or without ANCA were not detected. The anti-GBM response in both situations is hypothesized to be driven by the same immunogen, which is probably derived from NC1 domains of endogenous Type IV collagen.
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| 4. |
- van Timmeren, Mirjan M., et al.
(författare)
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IgG Glycan Hydrolysis Attenuates ANCA-Mediated Glomerulonephritis
- 2010
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Ingår i: Journal of the American Society of Nephrology. - 1046-6673. ; 21:7, s. 1103-1114
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Tidskriftsartikel (refereegranskat)abstract
- Anti-neutrophil cytoplasmic autoantibodies (ANCA) directed against myeloperoxidase (MPO) and proteinase 3 (Pr3) are considered pathogenic in ANCA-associated necrotizing and crescentic glomerulonephritis (NCGN) and vasculitis. Modulation of ANCA IgG glycosylation may potentially reduce its pathogenicity by abolishing Fc receptor mediated activation of leukocytes and complement Here, we investigated whether IgG hydrolysis by the bacterial enzyme endoglycosidase S (EndoS) attenuates ANCA-mediated NCGN. In vitro, treatment of ANCA IgG with EndoS significantly attenuated ANCA-mediated neutrophil activation without affecting antigen-binding capacity. In a mouse model of antiMPO IgG/LPS-induced NCGN, we induced disease with either unmodified or EndoS-treated (deglycosylated) anti-MPO IgG. In separate experiments, we administered EndoS systemically after disease induction with unmodified anti-MPO IgG. Pretreatment of anti-MPO IgG with EndoS reduced hematuria, leukocyturia, and albuminuria and attenuated both neutrophil influx and formation of glomerular crescents After inducing disease with unmodified anti-MPO IgG, systemic treatment with EndoS reduced albuminuria and glomerular crescent formation when initiated after 3 but not 24 hours. In conclusion, IgG glycan hydrolysis by EndoS attenuates ANCA-induced neutrophil activation in vitro and prevents induction of anti-MPO IgG/LPS-mediated NCGN m vivo. Systemic treatment with EndoS early after disease induction attenuates the development of disease. Thus, modulation of IgG glycosylation is a promising strategy to interfere with ANCA-mediated inflammatory processes.
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| 5. |
- Yang, Rui, et al.
(författare)
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Antigen and epitope specificity of anti-glomerular basement membrane antibodies in patients with Goodpasture disease with or without anti-neutrophil cytoplasmic antibodies
- 2007
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Ingår i: Journal of the American Society of Nephrology. - 1046-6673. ; 18:4, s. 1338-1343
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Tidskriftsartikel (refereegranskat)abstract
- Goodpasture disease (GP) is defined by the presence of anti-glomerular basement membrane (anti-GBM) antibodies and rapidly progressive glomerulonephritis. Besides anti-GBM, many patients with GP produce anti-neutrophil cytoplasmic antibodies (ANCA). For elucidation of the pathophysiologic significance of ANCA in this setting, epitope and antigen specificity of the anti-GBM antibodies and antigen specificity of ANCA were studied. Bovine testis a(IV)NC1 (tNC1); recombinant human alpha 1, alpha 3, alpha 4, and alpha 5(IV)NC1 (r alpha 1 through r alpha 5); and three chimeric proteins that contain previously defined epitope regions designated E-A, E-B, and S2 were used to examine the anti-GBM antibodies by ELISA in 205 Chinese patients with GP with or without ANCA. In the 205 anti-GBM antibody-positive sera, 63 (30.7%) were also ANCA positive (61 myeloperoxidase-ANCA and six proteinase 3-ANCA, four being triple positive). All 205 sera recognized tNC1 and r alpha 3(IV)NC1. In the double-positive group, 54.0, 66.7, 71.4% of the sera could recognize r alpha 1, r alpha 4, and r alpha 5, respectively, compared with 49.3, 60.6, and 55.6% for patients with anti-GBM antibodies alone. The levels of the antibodies to r alpha 3, tNC1, and the alpha 3/alpha 1 ratio were lower in the double-positive group than that in patients with anti-GBM antibody alone (P < 0.05). Most of the sera could recognize the epitope regions E-A,E-B, and S2, but the absorbance values to EA, EB, and S2 were lower in double-positive group (P < 0.05). Double-positive patients had a broader spectrum of anti-GBM antibodies and lower levels of antibodies against alpha 3(IV)NC1 compared with that of patients with anti-GBM antibodies alone.
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