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Background: Takayasu arteritis is a large-vessel vasculitis that affects the aorta and its primary branches. Myocarditis is a rare life-threatening complication and potential diagnostic pitfall in patients with Takayasu arteritis. Case summary: A previously healthy 18-year-old woman presenting with fever, back pain, and dyspnoea was admitted to another hospital for acute hypertension (blood pressure, 230/106 mmHg) and congestive heart failure. Intravenous methylprednisolone pulse with antihypertensive and diuretic medications slightly improved her congestion. However, she developed acute kidney injury and was transferred to our hospital. Transthoracic echocardiography indicated a left ventricular ejection fraction of 45% and diffuse left ventricular hypokinesis. Doppler ultrasound test and magnetic resonance angiography revealed severe bilateral renal artery stenosis. Her diagnosis was Takayasu arteritis, and she received high-dose glucocorticoids. She required temporary haemodialysis, but 2 months after admission, her serum creatinine improved to 1.1 mg/dL without surgical or cardiovascular interventions. Although the pre-discharge test with 1.5 T cardiac magnetic resonance initially failed to diagnose myocarditis, 3 T cardiac magnetic resonance imaging revealed increased native T1 values on T1 mapping (1283-1393 ms), moderate pericardial effusion, and systolic left ventricular wall motion abnormality, indicating active myocarditis. During 6-month subcutaneous tocilizumab treatment (162 mg/week), a left ventricular ejection fraction improved to 55-60% without a relapse. Discussion: This case report highlights the benefits of early multimodal imaging tests including cardiac magnetic resonance imaging for myocarditis and renal artery involvement in Takayasu arteritis. Tocilizumab might be an efficient therapeutic option for severe acute manifestations including myocarditis in young women of reproductive age.
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Immuno-mass spectrometry (MS) is a powerful method for the quantitative analysis of low-abundance proteins in biological specimens. In these procedures, collecting specifically and efficiently the target protein antigens from the antigen-antibody complex generated on the surface of nanocarrier beads is crucial and can be performed by hydrolyzing the proteins directly on the beads or after elution. Herein, we optimized the conditions of the immunoaffinity purification via elution using serum α-fetoprotein (AFP) as a model and its specific antibody immobilized covalently on magnetic beads. Antibody-coated beads were incubated with human serum spiked with standard AFP for antigen-antibody reaction. AFP was then eluted from the beads using various eluents, including organic solvents, to optimize the elution conditions. After proteolytically hydrolyzing the eluted protein, stable isotope-labeled standard peptides were added to the hydrolysate to quantify the eluted AFP via liquid chromatography-tandem MS. Using an optimized workflow for quantitative analysis afforded a correlation between the amount of spiked AFP and heavy to light ratios calculated based on peptide ion peak areas, from which an endogenous AFP concentration of 2.3±0.6 ng/mL was determined in normal serum; this is consistent with previous reports using radioimmunoassay methods. The present immuno-MS workflow could apply to the detection and quantitation of other low-abundance biofluid biomarkers.
RESUMO
Development of antibodies against the native structure of membrane proteins with multiple transmembrane domains is challenging because it is difficult to prepare antigens with native structures. Previously, we successfully developed a monoclonal antibody against multi-pass membrane protein TMEM180 by exosome immunization in rats. This approach yielded antibodies that recognized cancer-specific antigens on the exosome. In this study, we performed immunoprecipitation using magnetic beads to identify the antigen of one of the rat antibody clones, 0614, as CD73. We then converted antibody 0614 to human chimeric antibody 0614-5. Glioblastoma (GB) was the cancer type with the highest expression of CD73 in the tumor relative to healthy tissue. An antibody-drug conjugate (ADC) of 0614-5 exerted an antitumor effect on GB cell lines according to expression of CD73. The 0614-5-ADC has potential to be used to treat cancers with high CD73 expression. In addition, our strategy could be used to determine the antigen of any antibody produced by exosome immunization, which may allow the antibody to advance to new antibody therapies.
