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M Hirakata

Publications and source records attributed to M Hirakata.

At least 55 records · Page 3Linked to original sources
PubMed1996

Autoantibodies to DNA-dependent protein kinase. Probes for the catalytic subunit.

DNA-dependent protein kinase (DNA-PK) is an important nuclear enzyme which consists of a catalytic subunit known as DNA-PKcs and a regulatory component identified as the Ku autoantigen. In the present study, we surveyed 312 patients in a search for this specificity. 10 sera immunoprecipitated a large polypeptide which exactly comigrated with DNA-PKcs in SDS-PAGE. Immunoblot analysis demonstrated that this polypeptide was recognizable by a rabbit antiserum specific for DNA-PKcs. Although the patient sera did not bind to biochemically purified DNA-PKcs in immunoblots or ELISA, they were able to deplete DNA-PK catalytic activity from extracts of HeLa cells in a dose-dependent manner. We conclude that these antibodies should be useful probes for studies which aim to define the role of DNA-PK in cells. Since six sera simultaneously contained antibodies to the Ku protein, these studies suggest that relatively intact forms of DNA-PK complex act as autoantigenic particles in selected patients.

Antigens, Nuclear↗
PubMed1996

Autoantibodies to glycyl-transfer RNA synthetase in myositis. Association with dermatomyositis and immunologic heterogeneity.

OBJECTIVE: To elucidate the clinical significance and immunologic heterogeneity of anti-glycyl-transfer RNA (tRNA) synthetase antibodies in polymyositis/dermatomyositis (PM/DM). METHODS: Sera from 345 patients with rheumatic diseases, including 91 with myositis, were examined using immunoprecipitation assays. Autoantibodies to aminoacyl-tRNA synthetases were further analyzed with 2-dimensional RNA fractionation and via inhibition of in vitro aminoacylation. RESULTS: Serum from 1 patient with DM and interstitial lung disease immunoprecipitated glycyl-tRNA synthase along with only 1 of 4 associated tRNAs, in comparison with control anti-glycyl-tRNA synthetase antibodies, which bound the enzyme along with all 4 associated tRNAs. Immunoblotting findings and a lack of in vitro inhibition aminoacylation of tRNA(gly) by serum from this patient also suggested differences between the epitope specificity of this serum and that of other sera with anti-glycyl-tRNA synthetase antibodies. CONCLUSION: This identification of antibodies to glycyl-tRNA synthetase from a patient with DM underscores the association of this specificity with the disease. The finding that these antibodies bound an epitope outside the active site of the synthetase enzyme, in contrast to most anti-aminoacyl-tRNA synthetases, emphasizes the immunologic heterogeneity of these autoantibodies.

Antibody Specificity↗
PubMed1996

Autoimmunity to RNA polymerase II is focused at the carboxyl terminal domain of the large subunit.

OBJECTIVE: Previous studies have demonstrated antibodies to the large (220 kd) polypeptide subunit of RNA polymerase II (Pol II) in sera from certain patients with scleroderma. In the present study, we sought to identify the autoantigenic region on this polypeptide. METHODS: A recombinant fusion protein, corresponding to the 52-heptapeptide repeat found in the carboxyl terminal domain (CTD) of the large Pol II subunit, was used to identify 15 patient sera that contained autoantibodies. Synthetic peptides CTD7 (representing a single heptapeptide) and CTD18 (representing 2 1/2 heptapeptide repeats) were used in a competitive inhibition assay to define the specificity of these sera and the importance of the CTD as an autoantigen. RESULTS: All 15 sera immunoprecipitated the Pol II subunit from radiolabeled cell extracts, and 11 of them bound the CTD fusion protein in immunoblots. Immunoprecipitation of Pol II was completely inhibited by CTD18 in 5 sera and partially inhibited in 4 additional sera. CONCLUSION: These results indicate that the CTD heptapeptide repeat is a focal point for autoimmune responses in scleroderma. It is likely that the repetitive sequence and high content of charged residues of this structure contribute to its role as an autoantigen.

Adult↗
PubMed1996

Anti-U5 small nuclear ribonucleoprotein (snRNP) antibodies: a rare anti-U snRNP specificity.

We surveyed for autoantibodies to the U small nuclear ribonucleoproteins (snRNPs) in sera from 1171 patients with various connective tissue diseases by immunoprecipitation assay. We found serum, termed LaJ, which principally recognized the U5 snRNP from one patient with systemic sclerosis-polymyositis overlap syndrome. Anti-LaJ serum immunoprecipitated predominantly U5 snRNA from a 32PO4-labeled HeLa cell extract and at least five U5-specific proteins as well as the Sm core proteins from a [35S]methionine-labeled extract. Anti-LaJ serum immunoprecipitated both U5 snRNA and these five proteins in identical fractions at 15-20S by parallel sucrose gradient, suggesting physical association of these two components. Thus, we concluded that anti-LaJ serum contained antibody specific to the U5 snRNP. Antibodies specific to U5 snRNP were found in a single serum; in contrast, the prevalence of anti-U1 snRNP and anti-Sm antibody was considerably higher. Thus, the specific proteins of the U5 snRNP are rare targets for autoantibodies in patients with connective tissue disease.

Antibodies, Antinuclear↗
PubMed1996

[Two cases of interstitial pneumonia with anti-PL-12 (alanyl tRNA synthetase) antibodies].

We present two cases of interstitial pneumonia (IP) whose sera contain autoantibodies to PL-12 (alanyl tRNA synthetase). The first patient is a 47-year-old female who was diagnosed as IP and treated with corticosteroid at another hospital. She was admitted to Keio University Hospital due to worsening of dyspnea and polyarthritis. Laboratory studies revealed elevation of LDH and CRP, and her chest radiography showed interstitial fibrosis. Because of clinical deterioration, the dose of corticosteroid was increased (prednisolone 40 mg/day) and her symptom was stabilized. The second patient, a 55 year-old female, was admitted to Tokyo Metropolitan Ohtsuka Hospital because of dyspnea on exertion and polyarthritis. She did not show any symptom of myositis and was diagnosed as IP with arthritis on the basis of her clinical and chest radiography. She was treated with oral corticosteroid (prednisolone 30 mg/day), which resulted in improvement of her respiratory symptom and arthritis. Both patients were found to have autoantibodies to the PL-12. Autoantibodies to aminoacyl tRNA synthetases have been recognized as having a linkage with myositis mainly because of observations of the Jo-1 specificity. There was one report on a North American population that most but not all patients with anti-PL-12 antibodies had myositis. However, the clinical significance of anti-PL-12 has not been examined in Japanese patients. These patients suggested that anti-PL-12 antibodies have a stronger association with IP than myositis in Japanese patients.

Alanine-tRNA Ligase↗
PubMed1996

[Case of MPO-ANCA positive interstitial pneumonitis and necrotizing, crescentic glomerulonephritis].

A 52-year-old man was admitted to our hospital in July 1995, because of intermittent claudication, paresthesia on foot and gross hematuria. Chest radiograph in 1988 revealed bilateral interstitial shadows and proteinuria had been pointed out since 1992. On admission, chest X-ray and computed tomography showed diffuse interstitial shadow, however it had not been changed for several years. Laboratory tests revealed elevated level of erythrocyte sedimentation rate, C-reactive protein, immunoglobulin, rheumatoid factor, IgG-rheumatoid factor, and immune complex. Serum MPO-ANCA were positive. Although serum creatinine level and renal function test were normal, renal biopsy demonstrated crescentic formation and necrotizing vasculitis. Immunofluorescence and electron microscopy demonstrated no remarkable deposit in glomerulus. A diagnosis of microscopic polyarteritis necrotizing and crescentic glomerulonephritis (NCGN) was made. Treatment was initiated with 30 mg of prednisolone, followed by marked improvement of intermittent claudication, and decreased titer of serum MPO-ANCA. Previous reports have demonstrated the association of MPO-ANCA with rapidly progressive NCGN, microscopic polyarteritis, and occasionally pulmonary hemorrhage recognized as pulmonary-renal syndrome. However, the present case suggests the possibility that another disease subset may also be associated with MPO-ANCA, which is characterized by interstitial pneumonitis and slowly progressive glomerulonephritis.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1995

Massive pericardial effusion in scleroderma: a review of five cases.

Medical records of five patients with scleroderma (SSc), each of whom had pericardial effusion with an estimated volume of more than 200 ml, were reviewed to study the clinical and immunological significance of massive pericardial effusion in SSc. Diffuse SSc (4/5), with a wide area of pigmentation (4/5), flexion contracture (4/5), oesophageal hypomotility (5/5), pulmonary fibrosis (4/5) and autoantibodies to topoisomerase I (3/5) were the common features in this group. High protein, lactate dehydrogenase and low white blood cell count were the characteristics of pericardial fluid. None of the patients had signs of acute pericarditis. Four of the five cases died within 9 months of the diagnosis of pericarditis; two with renal failure, one with cardiac tamponade and another with sudden death. The pericarditis in diffuse SSc, especially in cases with anti-topoisomerase I, may be characterized by a chronic form of pericarditis with poor prognosis, often complicated by renal failure.

Adult↗
PubMed1995

[A case of rheumatoid arthritis complicated with salazosulfapyridine-induced aplastic anemia].

A 64 year-old woman with rheumatoid arthritis was admitted to our hospital because of general fatigue. She noticed polyarthralgia 8 months prior to the admission and diagnosis of rheumatoid arthritis was made. Administration of salazosulfapyridine (1.0 g/day) was started 6 months before the admission. Complete remission of rheumatoid arthritis was obtained in 2 months and blood cell counts showed normal values at that time. The results of laboratory tests included hemoglobin; 8.6 g/dl, white blood cell count; 1,900/mm3 with a differential of 19% neutrophils, 77% lymphocytes, and 4% monocytes; platelets were 21,000/mm3. A bone marrow aspiration and biopsy were performed. There were reduced numbers of myelocytes, erythroblasts, and megakaryocytes indicating aplastic anemia. Salazosulfapyridine was discontinued. Prednisolone, anabolic steroid and granulocyte-colony stimulating factor (G-CSF) were administrated. In spite of these therapy, recovery of peripheral blood cell counts have not been observed and supporting therapy including red cell and platelets transfusion have been continued. To our knowledge, this is the first case report which describes occurrence of aplastic anemia in patients with rheumatoid arthritis treated by salazosulfapyridine.

Anemia, Aplastic↗
PubMed1995

[Three cases with systemic rheumatic diseases who developed pulmonary lesions suggestive of bronchiolitis obliterans organizing pneumonia].

Three cases with systemic rheumatic diseases who developed lung diseases compatible with BOOP were reported. Underlying diseases of these patients were: RA (1 case), SLE (2 cases). Respiratory symptoms were observed in one case such as dry cough at the time of diagnosis of BOOP. Chest radiography showed multiple infiltrates in 2 cases, bilateral reticular shadow in one case. In one case characteristic finding described as wandering shadow was observed. TBLB was done in 3 cases. Pathohistological findings were compatible with BOOP. Repeated Bacteriological examinations failed to demonstrate specific organisms implicated for lung lesions. Cytological studies of sputum and TBLB specimens were all negative for malignancy. Antibiotic agents including anti-tuberculosis drugs were not effective for pulmonary diseases. Moderate doses of prednisolone were effective in 3 cases. Although the open lung biopsy has been recommended for establishment of diagnosis of BOOP, in patient with systemic rheumatic diseases this invasive procedure is not always easily performed. Further characterizations of clinical and laboratory features are indicated for noninvasive diagnosis of BOOP.

Adult↗
PubMed1995

[Interstitial lung disease in patients with connective tissue diseases].

Interstitial lung disease is a significant prognostic factor in connective tissue diseases. To further clarify clinical and immunological features of interstitial lung disease, we studied 894 consecutive patients with connective tissue diseases first evaluated between 1970 and 1993. Interstitial lung disease was found in 101 of 181 (56%) patients with systemic sclerosis, 92 of 183 (50%) with overlap syndrome, 35 of 76 (46%) with polymyositis/dermatomyositis, and 13 of 444 (3%) with systemic lupus erythematosus (p < 0.05, systemic lupus erythematosus vs. other connective tissue diseases). The presence of interstitial lung disease correlated with decreased survival in systemic sclerosis and in polymyositis/dermatomyositis, but not in overlap syndrome or in systemic lupus erythematosus. Interstitial lung disease in patients with connective tissue diseases was classified into two types: acute (n = 8) and chronic (n = 233). Among the 8 patients with acute disease, 4 (all with dermatomyositis) died of respiratory failure and 3 (all with systemic lupus erythematosus) responded to corticosteroids. Among the 233 patients with chronic interstitial lung disease, 20 had polymyositis/dermatomyositis with anti-aminoacyl tRNA synthetase antibodies and 40 had overlap syndrome with anti-U1 RNP antibodies. Respiratory failure in these patients was not frequent and occurred late in the course of the disease. As a cause of death, respiratory failure was associated with autoantibodies to topoisomerase I and aminoacyl tRNA synthetase but not anti-U1 RNP. Autoantibodies to aminoacyl tRNA synthetases were detected before the development of interstitial lung disease in 9 patients with polymyositis/dermatomyositis. We conclude that the clinical features of interstitial lung disease associated with connective tissue diseases vary with the type of connective tissue disease, and that analysis of autoantibodies can be useful in establishing a diagnosis and in forecasting the course and outcome.

Adult↗
PubMed1994

DNA-dependent protein kinase (Ku protein-p350 complex) assembles on double-stranded DNA.

The Ku protein is an autoantigen that consists of 70- and 80-kDa polypeptides. It associates with double-stranded DNA at free ends. In the present study, we examined the ability of anti-Ku antibodies to immunoprecipitate various structures from extracts of HeLa cells prepared at different salt concentrations. Under physiological conditions, these antibodies identified a complex containing the Ku protein and the 350-kDa component (p350) of DNA-dependent protein kinase (DNA-PK), which appeared to be closely associated on the DNA strand. In reconstitution experiments with cell extracts and biochemically purified components, the Ku protein-p350 complex formed only in the presence of double-stranded DNA. The reconstituted complex was catalytically active. Together with previous studies, these results indicate that the Ku protein interacts with DNA to create a binding site for p350 as the DNA-PK holoenzyme assembles.

Antigens, Nuclear↗
PubMed1994

Characterization of the Su antigen, a macromolecular complex of 100/102 and 200-kDa proteins recognized by autoantibodies in systemic rheumatic diseases.

The Su autoantigen was characterized biochemically using human and murine autoimmune sera and the clinical significance of anti-Su antibodies was studied in 236 Japanese and 160 American patients with systemic rheumatic diseases. Anti-Su in immunodiffusion (ID) was strongly associated with immunoprecipitation of one or more 100- to 102-kDa proteins by MRL/lpr mouse sera (27/32 of ID positive vs 4/20 of ID negative, P = 0.000016), and all four human anti-Su reference sera immunoprecipitated the 100/102-kDa protein(s). In addition, all sera immunoprecipitated a less efficiently labeled approximately 200-kDa protein that comigrated on sucrose density gradients with the 100/102-kDa proteins. Based on these data, a complex of the 100/102-kDa and 200-kDa proteins is likely to be the main target of anti-Su antibodies. Three of four anti-Su monospecific sera were negative for immunofluorescent antinuclear antibodies (ANA), suggesting anti-Su antibodies may be associated with a negative ANA in some cases. Autoantibodies to Su were detected frequently by immunoprecipitation in systemic lupus erythematosus (17-21%), scleroderma (13-20%), and overlap syndrome (22-40%) and were associated with autoantibodies to Ku.

Animals↗
PubMed1994

Autoantibodies to RNA polymerase II are common in systemic lupus erythematosus and overlap syndrome. Specific recognition of the phosphorylated (IIO) form by a subset of human sera.

Autoantibodies to RNA polymerases (RNAP) I, II, and III are reported to be highly specific for the diagnosis of scleroderma (systemic sclerosis, SSc). In the present study, the specificity of autoantibodies to RNAP I and III for SSc was confirmed by immunoprecipitation of 35S-labeled proteins. However, we report here the previously unrecognized production of anti-RNAP II autoantibodies by 9-14% of patients with SLE and mixed connective tissue disease/overlap syndrome. 12 out of 32 anti-RNAP II positive sera (group 1) immunoprecipitated a diffuse 220-240-kD band identified as the largest subunit of RNAP II whereas the remaining 20 (group 2) immunoprecipitated preferentially the 240-kD phosphorylated (IIo) form of the large subunit. After pulse labeling, group 1 sera immunoprecipitated only the 220-kD (IIa) RNAP II subunit, whereas the diffuse IIa/IIo band plus the 145-kD second largest RNAP II subunit (IIc) were immunoprecipitated after several hours of cold chase, suggesting that these sera recognized primarily the largest subunit of RNAP II. Group 2 sera recognized the IIc subunit after pulse labeling, and immunoprecipitated the IIc and IIo, but not the IIa, subunits after cold chase. Although it has been suggested that autoantibodies to RNAP II are usually accompanied by anti-RNAP I/III in SSc, all but one of the anti-RNAP II positive sera from SLE or mixed connective tissue disease/overlap syndrome patients, as well as most of the SSc sera, were negative for anti-RNAP I/III. Moreover, in contrast to previous reports suggesting that anti-RNAP antibodies rarely coexist with other SSc subset marker antibodies, anti-RNAP II antibodies were often accompanied by anti-Ku, anti-nRNP, or anti-topoisomerase I autoantibodies in the present study. We conclude that autoantibodies to RNAP II are not a specific marker for SSc, whereas autoantibodies to RNAP I/III are associated primarily with SSc. In addition, we have identified two distinctive patterns of RNAP II antigen recognition by autoantibodies, one of them characterized by specific recognition of the transcriptionally active (phosphorylated) form of RNAP II. The clinical significance of these different patterns remains to be determined.

Adult↗
PubMed1994

Onset of polymyositis with autoantibodies to threonyl-tRNA synthetase during pregnancy.

A 24-year-old black woman developed polymyositis with autoantibodies to threonyl-tRNA synthetase in the 2nd trimester of her 3rd pregnancy. This was complicated by fetal loss and the development of severe relapsing myositis resistant to corticosteroid and azathioprine therapy. These features were also common in other cases in the literature. Antisynthetase antibodies had not been reported in myositis occurring during pregnancy and may be of interest regarding the pathogenesis of inflammatory myopathy complicating pregnancy.

Adult↗
PubMed1993

Autoantigenic epitopes of the B and D polypeptides of the U1 snRNP. Analysis of domains recognized by the Y12 monoclonal anti-Sm antibody and by patient sera.

Anti-Sm antibodies, a specific marker for SLE, are directed against the B'/B and D polypeptides of Sm small nuclear ribonucleoproteins. The Y12 monoclonal anti-Sm antibody (Y12 mAb), as well as many anti-Sm patient sera, recognize cross-reactive epitopes on the B'/B and D polypeptides. This immunoreactive site is of special interest since polypeptides B and D share little amino acid sequence homology. In the present study, we have sought to establish the autoantigenic domain of polypeptides B and D that accounts for this epitope. We tested the ability of the Y12 mAb and anti-Sm sera to immunoprecipitate truncated forms of polypeptides B and D translated in vitro from mRNA bearing 5' and 3' end deletions. Most anti-Sm sera bound epitopes at the carboxyl-terminus of polypeptide B, however, autoantigenic epitopes were also found at the amino-terminus (amino acids 1 to 83 and 104 to 115). Surprisingly, the Y12 mAb recognized nonoverlapping amino-terminal and carboxyl-terminal halves of polypeptide B. One putative Y12 mAb binding site (amino acids 104 to 115) indicated by carboxyl-terminal deletion studies was confirmed through recognition of a corresponding synthetic peptide. Deletion studies with polypeptide D demonstrated a major autoantigenic domain on the carboxyl-terminus (amino acids 85 to 119) that was necessary for recognition by the Y12 mAb and by 7/14 patient sera. These results indicate that a cross-reactive epitope on B'/B and D, as defined by the Y12 mAb, resides on at least two different domains of polypeptide B and localizes to the carboxyl-terminus of polypeptide D. From the shared homology of truncated forms of B and D polypeptides recognizable with the Y12 mAb, we suspect that some form of GRG motif is involved in developing the Y12 mAb epitope that may involve other residues and be largely conformational in nature.

Amino Acid Sequence↗
PubMed1993

Identification of autoantibodies to RNA polymerase II. Occurrence in systemic sclerosis and association with autoantibodies to RNA polymerases I and III.

In this study, autoantibodies to RNA polymerase II from sera of patients with systemic sclerosis have been identified and characterized. These antibodies immunoprecipitated polypeptides of 220 kD (IIA) and 145 kD (IIC), the two largest subunits of RNA polymerase II, and bound both subunits in immunoblots. These polypeptides were immunoprecipitated by the anti-RNA polymerase II monoclonal antibody 8WG16, which recognizes the carboxyl-terminal domain of the 220-kD subunit, and their identity to the proteins bound by human sera was confirmed in immunodepletion studies. Sera with anti-RNA polymerase II antibodies also immunoprecipitated proteins that were consistent with components of RNA polymerases I and III. In vitro transcription experiments showed that the human antibodies were an effective inhibitor of RNA polymerase II activity. In indirect immunofluorescence studies, anti-RNA polymerase II autoantibodies stained the nucleoplasm, as expected from the known location of RNA polymerase II, and colocalized with the anti-RNA polymerase II monoclonal antibody. The human sera also stained the nucleolus, the location of RNA polymerase I. From a clinical perspective, these antibodies were found in 13 of 278 patients with systemic sclerosis, including 10 with diffuse and three with limited cutaneous disease, but were not detected in sera from patients with other connective tissue diseases and from normal controls. We conclude that anti-RNA polymerase II antibodies are specific to patients with systemic sclerosis, and that they are apparently associated with antibodies to RNA polymerases I and III. These autoantibodies may be useful diagnostically and as a probe for further studies of the biological function of RNA polymerases.

Adenoviridae↗