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Biomedical subjects

M Hirakata

Publications and source records attributed to M Hirakata.

At least 19 recordsLinked to original sources
PubMed2005

Autoantibody to CD40 ligand in systemic lupus erythematosus: association with thrombocytopenia but not thromboembolism.

OBJECTIVES: To examine the prevalence, clinical associations and pathogenic roles of autoantibodies to CD40 ligand (CD40L) in patients with systemic lupus erythematosus (SLE). METHODS: Plasma anti-CD40L antibodies from 125 patients with SLE, 24 with primary antiphospholipid syndrome (APS) and 90 with idiopathic thrombocytopenic purpura (ITP) and from 62 healthy individuals were measured with an enzyme-linked immunosorbent assay (ELISA). HeLa cells transfected with human CD40L cDNA (HeLa/CD40L) were used to confirm the presence of anti-CD40L autoantibodies. The effect of anti-CD40L antibodies on the CD40L-CD40 interaction was evaluated by observing CD40L-induced IkappaB activation in CD40-expressing fibroblasts. RESULTS: Anti-CD40L autoantibody was detected in seven (6%) SLE, three (13%) primary APS and 11 (12%) ITP patients, but in no healthy controls. Antibody binding in an ELISA was competitively inhibited by membrane components of HeLa/CD40L. Anti-CD40L antibody-positive IgG specifically bound the surface of living HeLa/CD40L, as shown by flow cytometry. The frequency of thrombocytopenia was significantly higher in SLE patients with the anti-CD40L antibody than in those without (100 vs 14%; P<0.00001), whereas there was no association between the anti-CD40L antibody and thrombosis. Binding of the anti-CD40L antibodies in patients' plasma to CD40L was competitively inhibited by a series of mouse anti-CD40L monoclonal antibodies. Anti-CD40L antibody-positive IgG failed to inhibit CD40L-induced IkappaB activation. CONCLUSIONS: Anti-CD40L autoantibody is associated with thrombocytopenia but not thromboembolism. Our findings are potentially useful in understanding the complex roles of CD40L in the pathophysiology of thrombosis and haemostasis as well as the thromboembolic complications that occur during treatment with anti-CD40L humanized antibody.

Adult↗
PubMed2004

Lack of circulating autoantibodies to bone morphogenetic protein receptor-II or activin receptor-like kinase 1 in mixed connective tissue disease patients with pulmonary arterial hypertension.

OBJECTIVES: To examine whether autoantibodies against bone morphogenetic protein receptor-II (BMPR-II) or activin receptor-like kinase 1 (ALK-1) are associated with pulmonary arterial hypertension (PAH) in patients with mixed connective tissue disease (MCTD). METHODS: We studied sera from 37 MCTD patients with or without PAH, six patients with idiopathic PAH, and 30 healthy controls. Circulating anti-BMPR-II and anti-ALK-1 antibodies were detected using immunoprecipitation of recombinant antigens generated by in vitro transcription/translation and indirect immunofluorescence of cultured cells that were induced to express these antigens by gene transfer. Anti-BMPR-II antibodies were further examined by immunoprecipitation and immunoblotting using a recombinant fragment of the extracellular domain of BMPR-II. RESULTS: Serum anti-BMPR-II and anti-ALK-1 autoantibodies were not detected in MCTD patients irrespective of the presence or absence of PAH, or in patients with idiopathic PAH. CONCLUSIONS: Our finding does not support the hypothesis that autoantibody-mediated dysregulation of signals through BMPR-II or ALK-1 contributes to the development of PAH in patients with connective tissue diseases.

Activin Receptors, Type I↗
PubMed2004

Autoantibodies from primary biliary cirrhosis patients with anti-p95c antibodies bind to recombinant p97/VCP and inhibit in vitro nuclear envelope assembly.

We have reported previously that p95c, a novel 95-kDa cytosolic protein, was the target of autoantibodies in sera of patients with autoimmune hepatic diseases. We studied 30 sera that were shown previously to immunoprecipitate a 95 kDa protein from [(35)S]-methionine-labelled HeLa lysates and had a specific precipitin band in immunodiffusion. Thirteen sera were available to test the ability of p95c antibodies to inhibit nuclear envelope assembly in an in vitro assay in which confocal fluorescence microscopy was also used to identify the stages at which nuclear assembly was inhibited. The percentage inhibition of nuclear envelope assembly of the 13 sera ranged from 7% to 99% and nuclear envelope assembly and the swelling of nucleus was inhibited at several stages. The percentage inhibition of nuclear assembly was correlated with the titre of anti-p95c as determined by immunodiffusion. To confirm the identity of this autoantigen, we used a full-length cDNA of the p97/valosin-containing protein (VCP) to produce a radiolabelled recombinant protein that was then used in an immunoprecipitation (IP) assay. Our study demonstrated that 12 of the 13 (93%) human sera with antibodies to p95c immunoprecipitated recombinant p97/VCP. Because p95c and p97 have similar molecular masses and cell localization, and because the majority of sera bind recombinant p97/VCP and anti-p95c antibodies inhibit nuclear assembly, this is compelling evidence that p95c and p97/VCP are identical.

Adenosine Triphosphatases↗
PubMed2002

Differences in autoantibody response to Th/To between systemic sclerosis and other autoimmune diseases.

OBJECTIVE: To examine differences in autoantibody response and immunogenetic background between patients with systemic sclerosis (SSc) and those with other autoimmune diseases who had serum anti-Th/To antibodies. METHODS: Serum samples from 1048 Japanese patients with various autoimmune diseases were screened for anti-Th/To antibodies using RNA and protein immunoprecipitation assays. The reactivity to RNase P subunits was examined by immunoprecipitating (35)S labelled recombinant Rpp38, Rpp30, and hPop1 produced by in vitro transcription and translation. HLA-DRB1, DQB1, and DPB1 alleles were identified using a polymerase chain reaction followed by a restriction fragment length polymorphism assay. RESULTS: Serum anti-Th/To antibodies were detected in 14 of 303 patients with SSc and seven of 745 patients without SSc (4.6% v 0.9%; p=0.0003). Similar percentages of patients with and without SSc showed immunoreactivity to Rpp38 and Rpp30, but more patients with SSc than patients without SSc showed a reactivity to hPop1 (93% v 14%; p=0.002). In patients with anti-Th/To antibodies DRB1*1502 or *0802 was detected more often, and the DRB1*0405-DQB1*0401 haplotype less often in patients with SSc than in patients without SSc (79% v 14%, p=0.02, and 7% v 71%, p=0.01, respectively). CONCLUSIONS: Anti-Th/To antibodies were detected in a small proportion of autoimmune patients lacking clinical features related to SSc. A close relationship between disease expression and anti-hPop1 reactivity as well as HLA class II alleles in anti-Th/To positive patients suggests that the process of anti-Th/To antibody production may be different between patients with and those without SSc.

Adolescent↗
PubMed2001

Human anti-asparaginyl-tRNA synthetase autoantibodies (anti-KS) increase the affinity of the enzyme for its tRNA substrate.

Autoantibodies directed against specific human aminoacyl-tRNA synthetases have been associated with a clinical picture including myositis, arthritis, interstitial lung disease and other features that has been referred to as the "anti-synthetase syndrome". Anti-asparaginyl-tRNA synthetase autoantibodies (anti-KS), the most recently described anti-synthetase autoantibodies, are directed against human cytosolic asparaginyl-tRNA synthetase and neutralize specifically its activity. Here we show that these antibodies recognize two epitopes on the human enzyme, an N-terminal epitope reactive in immunoblot experiments and a heat-labile epitope in the catalytic domain. In contrast to the well studied anti-Jo-1 autoantibodies anti-KS when bound to the synthetase increase the affinity of the synthetase for its tRNA substrate and prevent aminoacylation without interfering with the amino acid activation step.

Acylation↗
PubMed2001

Functional anatomy of musical perception in musicians.

The present study used functional magnetic resonance to examine the cerebral activity pattern associated with musical perception in musicians and non-musicians. Musicians showed left dominant secondary auditory areas in the temporal cortex and the left posterior dorsolateral prefrontal cortex during a passive music listening task, whereas non-musicians demonstrated right dominant secondary auditory areas during the same task. A significant difference in the degree of activation between musicians and non-musicians was noted in the bilateral planum temporale and the left posterior dorsolateral prefrontal cortex. The degree of activation of the left planum temporale correlated well with the age at which the person had begun musical training. Furthermore, the degree of activation in the left posterior dorsolateral prefrontal cortex and the left planum temporale correlated significantly with absolute pitch ability. The results indicated distinct neural activity in the auditory association areas and the prefrontal cortex of trained musicians. We suggest that such activity is associated with absolute pitch ability and the use-dependent functional reorganization produced by the early commencement of long-term training.

Adult↗
PubMed2001

Cytokine and immunogenetic profiles in Japanese patients with adult Still's disease. Association with chronic articular disease.

OBJECTIVE: To determine cytokines and MHC class II alleles in Japanese patients with adult Still's disease (ASD) and clarify the association between those profiles and chronic articular disease. METHODS: Of 35 patients with ASD (13 men, 22 women, mean age at onset 34.0 yr), 17 (49%) had chronic arthritis (>6 months, chronic articular ASD) and 18 (51%) lacked chronic arthritis (systemic ASD). Cytokines and cytokine receptors in sera were measured by ELISA. Correlations of each cytokine with disease activity or C-reactive protein (CRP) were determined. MHC class II alleles were examined by polymerase chain reaction methods. RESULTS: In chronic articular ASD, female gender was more frequent and liver dysfunction and myalgia were rarer than in systemic ASD. In active disease, the white blood cell count was lower, but total IgG was greater in patients with chronic articular ASD than in those with systemic ASD. Tumour necrosis factor (TNF) alpha, soluble TNF receptor 2 and interleukin (IL)-18 were increased in both types of ASD, even in remission. Soluble IL-2 receptors, IL-4 and IL-18 levels were correlated with disease activity or CRP value only in chronic articular ASD. Interferon gamma and IL-8 remained increased only in chronic articular ASD, even when disease activity, including IL-6 and CRP, was low. DRB1*1501 (DR2) and DRB1*1201 (DR5) alleles were more frequent in chronic articular than in systemic ASD, whereas DQB1*0602 (DQ1) was frequently observed in both types of ASD. CONCLUSION: The present study suggests that ASD with chronic articular disease has distinct clinical, cytokine and immunogenetic profiles.

Adult↗
PubMed2001

Expression and purification of recombinant rat eosinophil-associated ribonucleases, homologues of human eosinophil cationic protein and eosinophil-derived neurotoxin, and their characterization.

BACKGROUND: Human eosinophils contain two eosinophil ribonucleases, eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN). In rats, 8 homologues of human ECP and EDN have been identified. To clarify the biological activity of rat eosinophil ribonucleases, we cloned rat eosinophil-associated ribonuclease (EAR)-1/rat ribonuclease 7 and rat EAR-2/rat ribonuclease 4, and produced recombinant rat pre-EAR-1 and pre-EAR-2 in a bacterial expression system. METHODS: As we have already cloned the complete nucleotide sequence for rat EAR-1, we determined that for rat EAR-2 cDNA by the rapid amplification of cDNA ends procedure. Recombinant rat pre-EAR-1 and pre-EAR-2 were expressed in Escherichia coli as N-terminal 6 x histidine-tagged proteins, isolated from the insoluble fraction of the cell lysate and purified by a single-step method using an Ni-NTA resin column after solubilization with a 6 M guanidine solution. RESULTS: The deduced amino acid sequence revealed that the molecular weight of EAR-2 containing the signal peptide is 17.3 kD and the isoelectric point is 8.59. The homology in amino acid sequence between rat pre-EAR-2, and human pre-ECP and human pre-EDN is 51 and 53%, respectively. The purified and refolded recombinant rat pre-EAR-1 and pre-EAR-2 showed bactericidal activity against E. coli and Staphylococcus aureus. CONCLUSIONS: These findings suggest that rat EAR-1 and EAR-2 act as host defense factors against bacterial infection in rats.

Amino Acid Sequence↗
PubMed2000

Interstitial lung disease in polymyositis and dermatomyositis.

Interstitial lung disease (ILD) is common in patients with polymyositis (PM) and dermatomyositis (DM), and is a major cause of morbidity. Although its cause is unknown, it is known to be closely associated with autoimmune disorders. Its manifestation has been found to be quite heterogeneous, as demonstrated by the differences among PM/DM patients in their immunologic profiles and histopathologic findings, which suggest variations in immunopathogenetic mechanisms. We review the clinicopathologic and immunologic findings in ILD associated with PM/DM, and discuss recent advances in classification, autoantibodies, and treatment. The most critical issues are to clarify the immunopathogenesis of severe forms of ILD, such as rapidly progressive ILD associated with amyopathic DM, and to establish the most appropriate therapy.

Dermatomyositis↗
PubMed2000

Tyrosine-kinase dependent TGF-beta and extracellular matrix expression by mechanical stretch in vascular smooth muscle cells.

Vascular hypertrophy, which is characterized by proliferation of vascular smooth muscle cells (VSMC) and accumulation of extracellular matrix (ECM), is a major pathological change in blood vessels after chronic exposure to hypertension. Blood pressure is transmitted to the arterial walls and counterbalanced by mechanical stress, leading to stretching of circumferentially oriented VSMC, which may play some role in the pathogenesis of vascular hypertrophy. The present study was designed, therefore, to investigate the effect of mechanical stretch on the expression of ECM components and transforming growth factor-beta (TGF-beta), a potent stimulator for ECM production, and to examine the signal transduction mechanisms of the induction of TGF-beta in cultured rat VSMC. VSMC were subjected to cyclic stretch to provide a maximal elongation of 20% at a rate of 60 cycles per minute for up to 24 h. Mechanical stretch stimulated TGF-beta1 mRNA expression in a time- and elongation-dependent manner. Indeed, the secretion of TGF-beta proteins into the culture media was increased after stretch. Stretch also stimulated mRNA expression of the ECM components, type I and type IV collagen, and fibronectin, which was largely inhibited by addition of neutralizing antibody against TGF-beta. The tyrosine kinase inhibitors genistein and herbimycin A blocked the induction of TGF-beta1 and type I collagen by stretch, while protein kinase C inhibitors, the calcium channel blockers nitrendipine and gadolinium, or Ca removal from the media had no effect. These results suggest that stretch-induced, tyrosine kinase-mediated autocrine/paracrine production of TGF-8 may play a critical role in the progression of vascular remodeling associated with high blood pressure.

Animals↗
PubMed2000

Myositis and interstitial lung disease associated with autoantibody to a transfer RNA-related protein Wa.

We describe 2 patients with myositis and interstitial lung disease with the autoantibody to Wa antigen, a 48-kDa transfer RNA-related protein. In contrast to the previous description of anti-Wa antibody, our patients lacked systemic sclerosis-related features, but had clinical features consistent with those associated with antibodies to aminoacyl-transfer RNA synthetases. The difference in clinical presentation between our patients and patients with systemic sclerosis may be explained by recognition of different epitopes on the Wa antigen.

Aged↗
PubMed1999

Anti-KS: identification of autoantibodies to asparaginyl-transfer RNA synthetase associated with interstitial lung disease.

Autoantibodies to five of the aminoacyl-transfer RNA (tRNA) synthetases have been described, and each is associated with a syndrome of inflammatory myopathy with interstitial lung disease (ILD) and arthritis. Serum KS, from a patient with ILD and inflammatory arthritis without evidence of myositis, immunoprecipitated a tRNA that was distinct from that precipitated by any described anti-synthetase or other reported tRNA-related Abs, along with a protein of 65 kDa. KS serum and IgG fraction each showed significant (88%) inhibition of asparaginyl-tRNA synthetase (AsnRS) activity, but not of any of the other 19 aminoacyl-tRNA synthetase activities. Among 884 patients with connective tissue diseases tested, only two other sera were found to immunoprecipitate tRNAs and proteins of identical gel mobility. These two and KS showed identical immunodiffusion lines using HeLa cell extract. The new sera significantly inhibited AsnRS without significant effects on other synthetases tested. Both patients had ILD but neither had evidence of myositis. These data strongly suggest that these three sera have autoantibodies to AsnRS, representing a sixth anti-synthetase. Anti-KS was more closely associated with ILD than with myositis. Further study of this Abs might prove useful in dissecting the stimuli responsible for the genesis of anti-synthetase autoantibodies.

Adult↗
PubMed1999

Association of human leukocyte antigen class II genes with autoantibody profiles, but not with disease susceptibility in Japanese patients with systemic sclerosis.

OBJECT: To examine the role of human leukocyte antigen (HLA) class II genes in the development of systemic sclerosis (SSc) as well as in the clinical and serologic expression of SSc in patients. METHODS: HLA-DRB1, DRB3, DRB4, DQB1, and DPB1 alleles were determined by genotyping; and serum antinuclear antibodies were identified using indirect immunofluorescence, double immunodiffusion and immunoprecipitation. PATIENTS: One hundred and five Japanese patients with SSc and 104 race-matched healthy controls. RESULTS: Frequencies of DRB1 and DQB1 alleles were not different between SSc patients and healthy controls, while DPB1*0901 was marginally increased in SSc patients. In contrast, SSc-related autoantibodies were closely associated with the clinical features. HLA class II genes were detected as follows: anti-DNA topoisomerase I antibody with diffuse cutaneous involvement, pulmonary fibrosis, and DRB1*1502-DQB1*0601-DPB1*0901; anti-U1RNP antibody with overlapping features of lupus and/or myositis and DRB1*0401/*0802-DQB1*0302; and anticentromere antibody with limited cutaneous involvement and DRB1*0101-DQB1*0501-DPB1*0402. In the analysis of the association of HLA class II and the clinical features in SSc patients significant differences were obtained only for the increased frequencies of arthritis and rheumatoid factor in patients with DRB1*0405 compared to those without. CONCLUSION: HLA class II genes strongly influence the production of SSc-related autoantibodies rather than the development of SSc. In addition, SSc is a composite disease of distinctive subsets defined by serum autoantibodies, which have specific clinical and HLA class II associations.

Adolescent↗
PubMed1998

Spectrum and clinical significance of autoantibodies against transfer RNA.

OBJECTIVE: To characterize the clinical features of patients who have autoantibodies against transfer RNA (tRNA) or tRNA-associated proteins. METHODS: Sera from 1,472 patients with suspected systemic rheumatic disease were screened by RNA immunoprecipitation of HeLa cell extracts. The specificities of the antibodies that precipitated tRNAs were further analyzed by immunoprecipitation using deproteinized RNAs and 35S-methionine-labeled HeLa cell extracts, followed by immunoblotting. RESULTS: Forty-one serum samples (2.8%) were found to immunoprecipitate tRNAs. Thirteen patients were identified as having previously defined anti-aminoacyl-tRNA synthetase antibodies (anti-histidyl-tRNA synthetase in 4 patients, anti-threonyl-tRNA synthetase in 1, anti-alanyl-tRNA synthetase in 3, anti-glycyl-tRNA synthetase in 4, and anti-isoleucyl-tRNA synthetase in 1). All 13 patients had myositis and/or interstitial pneumonitis. Sera from the remaining 28 patients immunoprecipitated previously unidentified tRNAs, including 13 serum samples that bound deproteinized cognate tRNA; 24 of the 28 patients met criteria for either systemic lupus erythematosus (SLE) or Sjögren's syndrome (SS). In addition, nonerosive polyarthritis, leukocytopenia, rheumatoid factor, and characteristic annular or papulosquamous recurrent erythema were noted in these patients; however, renal involvement was rare. Sera from 16 of these 28 patients also contained anti-Ro/SSA and/or anti-La/SSB antibodies. While 189 patient sera precipitated Ro/SSA and/or La/SSB-associated RNAs but not tRNA, only 12 of the patients (6.3%) developed skin lesions (P=0.0009, odds ratio 8.85). CONCLUSION: Novel autoantibodies against tRNAs or tRNA-associated proteins were identified in 28 sera. These autoantibodies appear to be distinct from anti-aminoacyl-tRNA synthetase antibodies and are associated with SLE and SS. The presence of anti-Ro/SSA and/or anti-La/SSB along with anti-tRNA antibodies is more strongly associated with recurrent erythema than is the presence of anti-Ro/SSA or anti-La/SSB alone.

Adult↗