Biomedical subjects

Masakazu Matsushita

Publications and source records attributed to Masakazu Matsushita.

7 recordsLinked to original sources

PubMed2004

Glyceraldehyde 3-phosphate dehydrogenase is a novel autoantigen leading autoimmune responses to proliferating cell nuclear antigen multiprotein complexes in lupus patients.

Using 2-dimensional electrophoresis and ion-pair chromatography, we have identified elements of proliferating cell nuclear antigen (PCNA) multiprotein complexes that are reactive to antibodies in sera from patients with systemic lupus erythematosus. Among the various elements of the complexes, a 37 kDa protein (PI 8.5) that specifically reacted with SLE sera, but not with sera from patients with other connective tissue diseases, was identified as glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Immunoblot analysis showed that SLE sera reactive with the 37 kDa protein specifically reacted with GAPDH, as did anti-GAPDH mAbs. The purified autoantibodies to GAPDH from lupus serum showed both nuclear speckled and cytoplasmic staining patterns in immunofluorescence on Hep-2 cells. In addition, enzyme-linked immunosorbent assay (ELISA) revealed the presence of anti-GAPDH autoantibodies in 47% of lupus patients. Longitudinal analysis of the reactivity of lupus sera to PCNA complexes showed the autoimmune response to spread from GAPDH to other elements of PCNA complexes, and the presence of anti-GAPDH antibodies was significantly correlated with increased levels of serum PCNA. Taken together, these findings suggest that GAPDH interacting with PCNA in association with its cellular function is a novel autoantigen recognized by lupus sera, and that GAPDH thus plays an important role in the induction of autoimmune responses against the PCNA complex.

Animals↗

PubMed2004

Anticyclic citrullinated peptide antibodies in patients with mixed connective tissue disease.

The clinical significance of anticyclic citrullinated peptide (CCP) antibodies in patients with mixed connective tissue disease (MCTD) was assessed. Altogether, 86 sera from MCTD patients, 96 from rheumatoid arthritis (RA) patients, 42 from systemic lupus erythematosus (SLE) patients, 23 from systemic sclerosis (SSc) patients, 21 from polymyositis/dermatomyositis (PM/DM) patients, and 17 from those with Sjögren's syndrome (SjS) were tested for anti-CCP antibodies using an enzyme-lined immunosorbent assay. Among the 96 RA patients, anti-CCP antibodies were detected in 85%, with the frequency being significantly higher than in MCTD, SLE, SSc, PM/DM, and SjS patients (9%, 14%, 13%, 14%, and 18%, respectively; P < 0.001). Among eight MCTD patients who fulfilled the diagnostic criteria for RA, only 50% had anti-CCP antibodies, and the prevalence was significantly lower than for all RA patients (p < 0.01). All eight patients who fulfilled the criteria for RA had overlap of SLE and SSc, except one patient, whereas the four anti-CCP-positive patients who did not fulfill the criteria for RA had SjS without overlapping features of SLE and SSc; moreover, most of their antibody titers were low. These results suggested that anti-CCP antibodies are associated with RA in MCTD patients, but careful diagnosis of RA is required if patients with low titers of anti-CCP antibodies lack overlapping SLE and SSc.

Journal Article↗

PubMed2004

Autoimmune response to proteasome activator 28alpha in patients with connective tissue diseases.

OBJECTIVE: To determine the autoimmune response against proteasome activator 28alpha (PA28alpha) in patients with various connective tissue diseases, and to compare the immunoreactivity between anti-PA28alpha and anti-Ki antibodies. METHODS: Serum samples were obtained from 219 patients with various connective tissue diseases. cDNA encoding full-length human PA28alpha and Ki were produced by polymerase chain reaction. Antigens were expressed as glutathione S-transferase (GST) fusion proteins. The immunoreactivity of serum for PA28alpha and Ki was studied by Western blotting. An inhibition test was performed by ELISA using purified Ki antigen. RESULTS: Anti-PA28alpha> antibody was detected in serum from 23% of patients with systemic lupus erythematosus (SLE) and 24% with Sjögren's syndrome (SS). These rates were significantly higher than those for the other rheumatic diseases. Since both PA28alpha and Ki are elements of the PA28 complex and their amino acid sequences share 40.2% homology, immunoreactivity to PA28alpha was studied further. Among 27 anti-Ki positive serum samples, 13 samples (48%) also reacted with PA28alpha, suggesting a relationship between anti-PA28alpha and anti-Ki antibodies. To investigate whether this finding was due to the presence of cross-reacting epitopes for PA28alpha and Ki antigens, an inhibition test was performed by ELISA. The reactivity to purified Ki antigen was not inhibited by preincubation with recombinant PA28alpha. CONCLUSION: Detection of anti-PA28alpha antibody was significantly higher in serum from patients with SLE and SS. The relationship between anti-PA28alpha and Ki antibodies suggests the importance of an antigen-driven system in the induction of an autoimmune response to PA28 complex.

Antibody Specificity↗

PubMed2004

Autoimmune response to proteins of proliferating cell nuclear antigen multiprotein complexes in patients with connective tissue diseases.

OBJECTIVE: To analyze the autoimmune response to the proliferating cell nuclear antigen (PCNA) multiprotein complex in patients with connective tissue diseases (CTD). METHODS: The PCNA complex was purified by affinity chromatography using anti-PCNA monoclonal antibodies. Then 196 serum samples from patients with systemic lupus erythematosus (SLE) and 82 from patients with other CTD were tested for reactivity with the complex by immunoblotting. RESULTS: Of 196 SLE sera, 61 (31%) reacted with at least one component of the PCNA complex, and most reactive sera contained autoantibodies to several components of the complex. Autoantibodies to PCNA complex were less common in patients with other CTD, and most of their sera reacted only with one or a few proteins in the complex. Two out of 20 scleroderma sera reactive with 100, 85, and 70 kDa proteins in the PCNA complex also had autoantibodies to topoisomerase I (topo I) antibodies, which is an element of the complex. These findings suggest that the autoimmune response to the PCNA complex was specific for SLE. Anti-PCNA complex antibodies were associated with an increased serum level of PCNA detected by ELISA. The spreading of the autoimmune response to the elements of the complex was observed in parallel with the increased serum PCNA level when a series of sera from a lupus patient were tested longitudinally. In addition, anti-PCNA complex antibodies were significantly correlated with lupus erythematosus cells. CONCLUSION: The "antigen-drive" system may play a crucial role in inducing the autoimmune response to the PCNA complex in patients with SLE.

Autoimmunity↗

PubMed2003

Relationships between autoantibody responses to deletion mutants of Ki antigen and clinical manifestations of lupus.

OBJECTIVE: To determine the relationships between subtypes of anti-Ki antibodies and clinical manifestations of systemic lupus erythematosus. METHODS: The cDNA encoding full-length bovine Ki antigens or N- or C-terminal fragments were produced by polymerase chain reaction, and the fragments of Ki antigen were expressed as GST fusion proteins. Immunoreactivities of anti-Ki antibodies were tested by Western blotting. RESULTS: Of 60 sera reactive with full-length Ki antigen (KiF), 21 sera recognized only KiF. KiC5, a fragment containing the last 69 C-terminal amino acids, was recognized by 23 sera. Since no significant difference was observed in prevalence of reactivities between fragments from KiC2 to KiC5, a domain within the last 69 C-terminal amino acids was suggested to be the most common antigenic domain expressed among the GST fusion proteins. All 11 sera reacting with a fragment containing the initial 81 N-terminal amino acids also recognized all other fragments. A domain homologous to SV40 nuclear localization signal was required for N-terminal recognition by 8 sera. Reactivity to the last 69 C-terminal amino acids and the initial 81 N-terminal amino acids showed specificities to systemic lupus erythematosus without and with Sjögren's syndrome, respectively. Sicca was significantly more prevalent in patients whose sera reacted with both N- and C-terminal fragments, while prevalence of anti-SSA/Ro antibody was low. CONCLUSION: Ki antigen contains multiple epitopes recognized by autoimmune sera. Autoantibody profiles revealed distinctive immune responses, associated with certain clinical subtypes.

Autoantibodies↗

PubMed2002

Autoimmune responses to proliferating cell nuclear antigen multiprotein complexes involved in cell proliferation are strongly associated with their structure and biologic function in patients with systemic lupus erythematosus.

OBJECTIVE: To analyze the reaction of lupus sera with proliferating cell nuclear antigen (PCNA) multiprotein complexes (PCNA complexes), which are part of the protein machinery involved in cell proliferation. METHODS: PCNA complexes were purified from rabbit thymus extract by affinity chromatography using anti-PCNA monoclonal antibodies (TOB7, TO17, and TO30); monomeric and trimeric PCNA forms (AK-PCNA) were purified using anti-PCNA serum AK. The reactions to these antigens of 10 anti-PCNA-positive and 40 anti-PCNA-negative sera selected from 560 lupus patients were tested by immunoblotting, immunoprecipitation, and enzyme-linked immunosorbent assays (ELISAs). RESULTS: With one exception (serum OK), anti-PCNA-positive sera reacted exclusively with only the 34-kd polypeptide. In contrast, 14 of 40 anti-PCNA-negative sera reacted with multiple proteins within PCNA complexes. Most anti-PCNA-positive sera probably recognize as epitopes the binding sites for other proteins on PCNA, which are likely hidden when PCNA is complexed with other proteins. As a consequence, only serum OK reacted with the PCNA complex in a series of ELISAs. Using AK-PCNA as a competitive inhibitor, it was determined that serum OK reacts with both the 58-kd polypeptide and the 34-kd PCNA within complexes. Together with the results of a longitudinal analysis, these results suggest that the immune system of patient OK likely recognized the complexed PCNA protein, after which the autoimmune response spread to other elements of the complexes. CONCLUSION: Intermolecular-intrastructural help, leading to the spread of autoimmune response from PCNA to other proteins associated with its biologic function, plays a crucial role in the induction of the autoimmune response seen in lupus patients.

Antibodies, Monoclonal↗

PubMed2002

Interaction between fluvoxamine and cotinine or caffeine.

We examined the relationships between plasma fluvoxamine concentrations and plasma levels of cotinine and caffeine, respectively, under steady-state conditions in 30 patients who met DSM-IV criteria for a major depressive disorder and who were being treated with fluvoxamine. The daily dosages of fluvoxamine ranged from 50 to 200 mg (mean +/- SD 108 +/- 42 mg). Eleven patients were smokers and the remaining 19 were nonsmokers. The plasma fluvoxamine concentrations were significantly higher in nonsmokers (0.92 +/- 0.40 ng/ml/mg) than in smokers (0.56 +/- 0.28 ng/ml/mg); in addition, a trend towards negative correlations was observed between the plasma fluvoxamine concentrations and the plasma cotinine levels, although it was not significant. Significant positive correlations were found between the plasma fluvoxamine concentrations and the plasma caffeine levels. These findings are compatible with those in earlier reports that cytochrome P450 1A2 plays a major role in fluvoxamine metabolism.

Adult↗