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Novel Autoantigens Associated with Lupus Nephritis.

Onishi S, Adnan E, Ishizaki J, Miyazaki T, Tanaka Y, Matsumoto T, Suemori K, Shudou M, Okura T, Takeda H, Sawasaki T, Yasukawa M, Hasegawa H - PLoS ONE (2015)

Bottom Line: To obtain other autoantibodies associated with LN, we screened autoantigens reacting with the sera of LN patients by using an N-terminal biotinylated protein library created from a wheat cell-free protein production system.Both proteins are cationic, and their respective antibodies did not cross-react with dsDNA.These autoantibodies may be useful for prediction of LN in subsets of SLE patients who are negative for anti-dsDNA antibodies.

View Article: PubMed Central - PubMed

Affiliation: Department of Hematology, Clinical Immunology and Infectious Diseases, Ehime University Graduate School of Medicine, Ehime, Japan.

ABSTRACT
Systemic lupus erythematosus (SLE) is characterized by production of a variety of autoantibodies. Although anti-double-stranded DNA (anti-dsDNA) antibodies contribute to the pathogenesis of lupus nephritis (LN), they are not sufficient for diagnosis and evaluation of disease activity. To obtain other autoantibodies associated with LN, we screened autoantigens reacting with the sera of LN patients by using an N-terminal biotinylated protein library created from a wheat cell-free protein production system. We screened 17 proteins that showed higher positive signals in the active phase than in the inactive phase of SLE, and higher positive signals in the serum of SLE patient with nephritis than in that of patient without nephritis. Of these, two LN-associated autoantigens, ribosomal RNA-processing protein 8 (RRP8) and spermatid nuclear transition protein 1 (TNP1) were identified by immunoprecipitation and immunofluorescence of renal tissues. Circulating anti-RRP8 and anti-TNP1 autoantibodies were recognized and deposited as an immune complex (IC) in glomeruli. IC was deposited preferentially in glomeruli rather than in other organs in C57BL/6 mice injected with RRP8 or TNP1. ELISA analysis of sera from patients with various rheumatic diseases demonstrated reactivity for RRP8 and TNP1 in 20% and 14.7% of SLE patients, respectively, whereas there was little or no reactivity in patients with other rheumatic diseases. Among SLE patients, 63.6% and 45.5% of those with LN were positive for anti-RRP8 and anti-TNP1 antibodies, compared with 12.5% and 9.4% of SLE patients without nephritis, respectively. Both proteins are cationic, and their respective antibodies did not cross-react with dsDNA. These proteins released from apoptotic cells form ICs with each autoantibody, and their ICs may become trapped at anionic sites in the glomerular basement membrane, leading to deposition in glomeruli. These autoantibodies may be useful for prediction of LN in subsets of SLE patients who are negative for anti-dsDNA antibodies.

No MeSH data available.


Related in: MedlinePlus

Serum levels of anti-RRP8 (A) and anti-TNP1 (B) antibodies in patients with rheumatic diseases.Cut-off values for positivity (9.1 units for anti-RRP8 antibody and 10.6 units for anti-TNP1 antibody) are indicated by the dotted lines. LN, lupus nephrits; SLE, systemic lupus erythematosus without LN; DM, dermatomyositis; PM, polymyositis; SSc, systemic sclerosis; MCTD, mixed connective tissue disease; RA, rheumatoid arthritis; SS, Sjögren syndrome; BD, Behçet’s disease; AAV, anti-neutrophil cytoplasmic antibody-associated vasculitis.
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pone.0126564.g003: Serum levels of anti-RRP8 (A) and anti-TNP1 (B) antibodies in patients with rheumatic diseases.Cut-off values for positivity (9.1 units for anti-RRP8 antibody and 10.6 units for anti-TNP1 antibody) are indicated by the dotted lines. LN, lupus nephrits; SLE, systemic lupus erythematosus without LN; DM, dermatomyositis; PM, polymyositis; SSc, systemic sclerosis; MCTD, mixed connective tissue disease; RA, rheumatoid arthritis; SS, Sjögren syndrome; BD, Behçet’s disease; AAV, anti-neutrophil cytoplasmic antibody-associated vasculitis.

Mentions: We compared the circulating levels of anti-RRP8 and anti-TNP1 antibodies among patients with rheumatic diseases using ELISA. We analyzed a total of 238 serum samples obtained from patients with various rheumatic diseases (S4 Table). When the cut-off value was considered to be the mean plus 5 standard deviations (SD) for 41 healthy control sera, the cut-off level for anti-RRP8 and anti-TNP1 antibodies was set at 9.1 units and 10.6 units, respectively. Among these serum samples, anti-RRP8 antibody was positive in 20 patients; 15 SLE, 1 DM/PM, 3 RA and 1 BD (Fig 3A). Among the SLE patients, the positive rate of anti-RRP8 antibody was significantly higher in LN than that in SLE without nephritis (63.6% (n = 7) vs 12.5% (n = 8), respectively; p = 0.00017, odds ratio 12.25, 95% confidence interval 2.9–51.4). On the other hand, 14 were positive for anti-TNP1 antibody; 11 SLE, 1 RA and 2 BD (Fig 3B). The frequency of anti-TNP1 antibody was significantly higher in the SLE patients with nephritis than in those without nephritis (45.5% (n = 5) vs 9.4% (n = 6), respectively; p = 0.002, odds ratio 8.06, 95% confidence interval 1.8–34.5). These findings indicate that both anti-RRP8 and anti-TNP1 antibodies are strongly associated with LN.


Novel Autoantigens Associated with Lupus Nephritis.

Onishi S, Adnan E, Ishizaki J, Miyazaki T, Tanaka Y, Matsumoto T, Suemori K, Shudou M, Okura T, Takeda H, Sawasaki T, Yasukawa M, Hasegawa H - PLoS ONE (2015)

Serum levels of anti-RRP8 (A) and anti-TNP1 (B) antibodies in patients with rheumatic diseases.Cut-off values for positivity (9.1 units for anti-RRP8 antibody and 10.6 units for anti-TNP1 antibody) are indicated by the dotted lines. LN, lupus nephrits; SLE, systemic lupus erythematosus without LN; DM, dermatomyositis; PM, polymyositis; SSc, systemic sclerosis; MCTD, mixed connective tissue disease; RA, rheumatoid arthritis; SS, Sjögren syndrome; BD, Behçet’s disease; AAV, anti-neutrophil cytoplasmic antibody-associated vasculitis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4476694&req=5

pone.0126564.g003: Serum levels of anti-RRP8 (A) and anti-TNP1 (B) antibodies in patients with rheumatic diseases.Cut-off values for positivity (9.1 units for anti-RRP8 antibody and 10.6 units for anti-TNP1 antibody) are indicated by the dotted lines. LN, lupus nephrits; SLE, systemic lupus erythematosus without LN; DM, dermatomyositis; PM, polymyositis; SSc, systemic sclerosis; MCTD, mixed connective tissue disease; RA, rheumatoid arthritis; SS, Sjögren syndrome; BD, Behçet’s disease; AAV, anti-neutrophil cytoplasmic antibody-associated vasculitis.
Mentions: We compared the circulating levels of anti-RRP8 and anti-TNP1 antibodies among patients with rheumatic diseases using ELISA. We analyzed a total of 238 serum samples obtained from patients with various rheumatic diseases (S4 Table). When the cut-off value was considered to be the mean plus 5 standard deviations (SD) for 41 healthy control sera, the cut-off level for anti-RRP8 and anti-TNP1 antibodies was set at 9.1 units and 10.6 units, respectively. Among these serum samples, anti-RRP8 antibody was positive in 20 patients; 15 SLE, 1 DM/PM, 3 RA and 1 BD (Fig 3A). Among the SLE patients, the positive rate of anti-RRP8 antibody was significantly higher in LN than that in SLE without nephritis (63.6% (n = 7) vs 12.5% (n = 8), respectively; p = 0.00017, odds ratio 12.25, 95% confidence interval 2.9–51.4). On the other hand, 14 were positive for anti-TNP1 antibody; 11 SLE, 1 RA and 2 BD (Fig 3B). The frequency of anti-TNP1 antibody was significantly higher in the SLE patients with nephritis than in those without nephritis (45.5% (n = 5) vs 9.4% (n = 6), respectively; p = 0.002, odds ratio 8.06, 95% confidence interval 1.8–34.5). These findings indicate that both anti-RRP8 and anti-TNP1 antibodies are strongly associated with LN.

Bottom Line: To obtain other autoantibodies associated with LN, we screened autoantigens reacting with the sera of LN patients by using an N-terminal biotinylated protein library created from a wheat cell-free protein production system.Both proteins are cationic, and their respective antibodies did not cross-react with dsDNA.These autoantibodies may be useful for prediction of LN in subsets of SLE patients who are negative for anti-dsDNA antibodies.

View Article: PubMed Central - PubMed

Affiliation: Department of Hematology, Clinical Immunology and Infectious Diseases, Ehime University Graduate School of Medicine, Ehime, Japan.

ABSTRACT
Systemic lupus erythematosus (SLE) is characterized by production of a variety of autoantibodies. Although anti-double-stranded DNA (anti-dsDNA) antibodies contribute to the pathogenesis of lupus nephritis (LN), they are not sufficient for diagnosis and evaluation of disease activity. To obtain other autoantibodies associated with LN, we screened autoantigens reacting with the sera of LN patients by using an N-terminal biotinylated protein library created from a wheat cell-free protein production system. We screened 17 proteins that showed higher positive signals in the active phase than in the inactive phase of SLE, and higher positive signals in the serum of SLE patient with nephritis than in that of patient without nephritis. Of these, two LN-associated autoantigens, ribosomal RNA-processing protein 8 (RRP8) and spermatid nuclear transition protein 1 (TNP1) were identified by immunoprecipitation and immunofluorescence of renal tissues. Circulating anti-RRP8 and anti-TNP1 autoantibodies were recognized and deposited as an immune complex (IC) in glomeruli. IC was deposited preferentially in glomeruli rather than in other organs in C57BL/6 mice injected with RRP8 or TNP1. ELISA analysis of sera from patients with various rheumatic diseases demonstrated reactivity for RRP8 and TNP1 in 20% and 14.7% of SLE patients, respectively, whereas there was little or no reactivity in patients with other rheumatic diseases. Among SLE patients, 63.6% and 45.5% of those with LN were positive for anti-RRP8 and anti-TNP1 antibodies, compared with 12.5% and 9.4% of SLE patients without nephritis, respectively. Both proteins are cationic, and their respective antibodies did not cross-react with dsDNA. These proteins released from apoptotic cells form ICs with each autoantibody, and their ICs may become trapped at anionic sites in the glomerular basement membrane, leading to deposition in glomeruli. These autoantibodies may be useful for prediction of LN in subsets of SLE patients who are negative for anti-dsDNA antibodies.

No MeSH data available.


Related in: MedlinePlus