The Fc region of IgG antibodies (Cγ2 and Cγ3 domains) is responsible for effector functions such as antibody-dependent cell-mediated cytotoxicity and phagocytosis, through engagement with Fcγ receptors, although the ability to elicit these functions differs between the four human IgG subclasses. A key determinant of Fcγ receptor interactions is the FG loop in the Cγ2 domain. High resolution cryogenic IgG4-Fc crystal structures have revealed a unique conformation for this loop, which could contribute to the particular biological properties of this subclass. To further explore the conformation of the IgG4 Cγ2 FG loop at near-physiological temperature, we solved a 2.7Å resolution room temperature structure of recombinant human IgG4-Fc from crystals analysed in situ. The Cγ2 FG loop in one chain differs from the cryogenic structure, and adopts the conserved conformation found in IgG1-Fc; however, this conformation participates in extensive crystal packing interactions. On the other hand, at room temperature, and free from any crystal packing interactions, the Cγ2 FG loop in the other chain adopts the conformation previously observed in the cryogenic IgG4-Fc structures, despite both conformations being accessible. The room temperature human IgG4-Fc structure thus provides a more complete and physiologically relevant description of the conformation of this functionally critical Cγ2 FG loop.

2016-07-01·Journal of Cardiovascular Pharmacology4区 · 医学

Recombinant Human Alpha-1 Antitrypsin-Fc Fusion Protein Reduces Mouse Myocardial Inflammatory Injury After Ischemia–Reperfusion Independent of Elastase Inhibition

4区 · 医学

Article

作者: Dinarello, Charles A. ; Rose, Scott W. ; Van Tassell, Benjamin W. ; Mauro, Adolfo G. ; Kim, Soohyun ; Toldo, Stefano ; Mezzaroma, Eleonora ; Abbate, Antonio ; Marchetti, Carlo

Background:Alpha-1-antitrypsin (AAT) is an abundant plasma protein with neutrophil elastase-inhibiting activity, and AAT is available as a plasma-derived therapeutic (pAAT). In experimental myocardial infarction, pAAT reduced acute inflammatory injury because of ischemia–reperfusion. The aim of the present study was to assess the properties of a recombinant protein composed of human AAT fused to the human immunoglobulin (Ig) G1 Fc fragment (rhAAT-Fc) in experimental myocardial infarction.Methods:Ten-week-old CD1 male mice underwent transient occlusion (30 minutes) of the left anterior coronary artery. rhAAT-Fc (2 mg/kg) or pAAT (60 mg/kg) were administered upon reperfusion. We used human plasma-derived Ig (2 mg/kg) or a matching volume of NaCl 0.9% as control solutions. After 24 hours, infarct size and caspase-1 activity were quantified. The left ventricular ejection fraction (LVEF) was measured by echocardiography at 24 hours and 7 days. A variant of rhAAT-Fc lacking elastase inhibition activity, rhAAT-Fc[E−], was also tested.Results:The rhAAT-Fc induced a significant reduction in infarct size (P < 0.01 vs. all controls, P > 0.05 vs. pAAT). Caspase-1 activity was reduced to the same degree with rhAAT-Fc and pAAT (−70%; P < 0.05; P > 0.05 rhAAT-Fc vs. pAAT). The effects on infarct size after a single administration were reflected by preservation of LVEF at 24 hours and 7 days (all P < 0.05). rhAAT-Fc without elastase inhibiting activity, rhAAT-Fc[E−], conferred comparable effects on infarct size, caspase-1 activity, and LVEF (P > 0.2 vs. rhAAT-Fc).Conclusions:The pAAT and recombinant human AAT-Fc reduce the acute myocardial inflammatory injury after ischemia–reperfusion in the mouse leading to preservation of viable myocardium and systolic function, independent on the effects on neutrophil elastase.

2013-03-01·Intensive Care Medicine1区 · 医学

Carbamylated erythropoietin-FC fusion protein and recombinant human erythropoietin during porcine kidney ischemia/reperfusion injury

1区 · 医学

Article

作者: Enrico Calzia ; Oscar McCook ; Šárka Matějková ; Angelika Scheuerle ; Peter Radermacher ; Peter Möller ; Florian Simon ; Michael Georgieff ; Bettina Stahl ; Hubert Schelzig ; Florian Wagner ; Michael Gröger ; José Matallo ; Brigitta Vcelar ; Andrea Seifritz

PURPOSETo test the hypothesis that a carbamylated EPO-FC fusion protein (cEPO-FC) or recombinant human erythropoietin (rhEPO) would protect against kidney ischemia/reperfusion (I/R) injury in pigs with atherosclerosis.METHODSAnesthetized and mechanically ventilated animals received cEPO-FC (50 μg kg(-1)), rhEPO (5,000 IU kg(-1)), or vehicle (n = 9 per group) prior to 120 min of aortic occlusion and over 4 h of reperfusion. During aortic occlusion, mean arterial pressure (MAP) was maintained at 80-120 % of baseline values by esmolol, nitroglycerin, and ATP. During reperfusion, noradrenaline was titrated to keep MAP at pre-ischemic levels. Blood creatinine and neutrophil gelatinase-associated lipocalin (NGAL) levels, creatinine clearance, fractional Na(+) excretion, and HE and PAS staining were used to assess kidney function and histological damage. Plasma interleukin-6, tumor necrosis factor-α, nitrate + nitrite and 8-isoprostane levels were measured to assess systemic inflammation, and nitrosative and oxidative stress.RESULTSI/R caused acute kidney injury with reduced creatinine clearance, increased fractional Na(+) excretion and NGAL levels, moderate to severe glomerular and tubular damage and apoptosis, systemic inflammation and oxidative and nitrosative stress, but there were no differences between the treatment groups. Pre-ischemia nitrate + nitrite and 8-isoprostanes levels were lower and higher, respectively, than in healthy animals of a previous study, and immune histochemistry showed higher endothelial nitric oxide synthase and lower EPO receptor expression in pre-ischemia kidney biopsies than in biopsies from healthy animals.CONCLUSIONSIn swine with atherosclerosis, rhEPO and cEPO-FC failed to attenuate prolonged ischemia-induced kidney injury within an 8-h reperfusion period, possibly due to reduced EPO receptor expression resulting from pre-existing oxidative stress and/or reduced NO release.

100 项与重组人促红细胞生成素-Fc融合蛋白(隆延生物科技（上海）有限公司) 相关的药物交易

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