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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

Immunoprecipitation of RRP8 and TNP1 with sera from patients with rheumatic diseases.Reprisentative photographs are shown. (A) RRP8 (50.7 kDa) (B) TNP1 (GST-tagged, 32.4 kDa). LN; active lupus nephritis, SLE; systemic lupus erythematosus without active lupus nephritis, DM; dermatomyositis, SSc; systemic sclerosis, cont; healthy control.
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pone.0126564.g001: Immunoprecipitation of RRP8 and TNP1 with sera from patients with rheumatic diseases.Reprisentative photographs are shown. (A) RRP8 (50.7 kDa) (B) TNP1 (GST-tagged, 32.4 kDa). LN; active lupus nephritis, SLE; systemic lupus erythematosus without active lupus nephritis, DM; dermatomyositis, SSc; systemic sclerosis, cont; healthy control.

Mentions: The biotinylated proteins of 17 autoantigens were prepared using the wheat germ cell-free protein synthesis system. Immunoprecipitation analysis using these biotinylated proteins was performed using sera from patients with the following diseases: 5 with active LN, 5 with SLE without nephritis, 5 with DM/PM, and 5 with SSc (S3 Table). Antibodies against RRP8, TNP1, sperm protamine P1 (PRM1), and protamine 2 (PRM2), were detected in the sera from SLE patients, while antibody against junctional sarcoplasmic reticulum protein 1 (JSRP1) was detected not only in the sera from SLE patients but also in sera from DM and SSc patients. The antibodies against PRM1 and PRM2 were detected in the sera from SLE patients with and without nephritis, although these positive signals were weak. Antibodies against RRP8 and TNP1 were detected specifically in patients with LN. As shown in Fig 1A and 1B, two proteins, RRP8 and TNP1, reacted with the sera from 2 and 1 LN patients, respectively. These two proteins did not react with any serum from healthy controls, SLE patients without nephritis, or DM/PM and SSc patients used in this experiment. These findings suggest that RRP8 and TNP1 are 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)

Immunoprecipitation of RRP8 and TNP1 with sera from patients with rheumatic diseases.Reprisentative photographs are shown. (A) RRP8 (50.7 kDa) (B) TNP1 (GST-tagged, 32.4 kDa). LN; active lupus nephritis, SLE; systemic lupus erythematosus without active lupus nephritis, DM; dermatomyositis, SSc; systemic sclerosis, cont; healthy control.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0126564.g001: Immunoprecipitation of RRP8 and TNP1 with sera from patients with rheumatic diseases.Reprisentative photographs are shown. (A) RRP8 (50.7 kDa) (B) TNP1 (GST-tagged, 32.4 kDa). LN; active lupus nephritis, SLE; systemic lupus erythematosus without active lupus nephritis, DM; dermatomyositis, SSc; systemic sclerosis, cont; healthy control.
Mentions: The biotinylated proteins of 17 autoantigens were prepared using the wheat germ cell-free protein synthesis system. Immunoprecipitation analysis using these biotinylated proteins was performed using sera from patients with the following diseases: 5 with active LN, 5 with SLE without nephritis, 5 with DM/PM, and 5 with SSc (S3 Table). Antibodies against RRP8, TNP1, sperm protamine P1 (PRM1), and protamine 2 (PRM2), were detected in the sera from SLE patients, while antibody against junctional sarcoplasmic reticulum protein 1 (JSRP1) was detected not only in the sera from SLE patients but also in sera from DM and SSc patients. The antibodies against PRM1 and PRM2 were detected in the sera from SLE patients with and without nephritis, although these positive signals were weak. Antibodies against RRP8 and TNP1 were detected specifically in patients with LN. As shown in Fig 1A and 1B, two proteins, RRP8 and TNP1, reacted with the sera from 2 and 1 LN patients, respectively. These two proteins did not react with any serum from healthy controls, SLE patients without nephritis, or DM/PM and SSc patients used in this experiment. These findings suggest that RRP8 and TNP1 are 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