Marinobufagenin as a therapeutic target

首先，我们研究了Mg2+离子是否可以增强DigiFab对PE和对照组妊娠红细胞NKA活性的体外恢复的影响。我们研究了DigiFab、Mg2+以及两者联合使用对PE患者红细胞NKA活性的影响。在无并发症妊娠患者的红细胞中，我们比较了Mg2+不存在或Mg2+与DigiFab联合使用时MBG浓度增加的体外抑制活性。与对照组相比，PE患者血浆MBG升高3倍与红细胞NKA活性降低2.5倍相关。红细胞与Mg2+或DigiFab预孵育可增加NKA活性，Mg2+和DigiFab联合使NKA活性恢复到控制水平。对照红细胞中MBG的nka抑制活性被Mg2+右移。Mg2+与DigiFab联用可显著增强DigiFab对MBG的免疫中和作用，使NKA对MBG的敏感性降低。这些结果表明，镁能够提高DigiFab对mbg诱导的PE NKA抑制的免疫中和作用，很有可能增强DigiFab的降压作用，这可能作为PE的降压治疗具有重要的临床应用价值。

First we studied, whether Mg2+ ions can potentiate the effect of DigiFab on the restoration of erythrocyte NKA activity ex vivo in PE vs. control pregnancy. We have examined the effect of DigiFab, Mg2+ and a combination of both on erythrocyte NKA activity in patients with PE. In erythrocytes from patients with uncomplicated pregnancies, we compared ex vivo inhibitory activity of incremental MBG concentration in the absence or presence of Mg2+, or combination of Mg2+ and DigiFab. Three-fold elevated plasma MBG in PE patients was associated with a 2.5-fold decrease of erythrocyte NKA activity vs. control. Preincubation of erythrocytes with Mg2+ or DigiFab increased NKA activity, and combination of both Mg2+ and DigiFab restored NKA activity to control level. NKA-inhibitory activity of MBG in control erythrocytes is shifted to the right by Mg2+. Combination of Mg2+ and DigiFab significantly potentiated immunoneutralizing effect of DigiFab on MBG, making NKA less sensitive to MBG. These findings indicate that magnesium is capable of increasing the efficacy of DigiFab in immunoneutralization of MBG-induced NKA inhibition in PE with a high probability to potentiate anti-hypertensive effect of DigiFab, which may have an important clinical application as antihypertensive therapy in PE. In a second study, we first measured plasma MBG levels and performed comprehensive clinical, laboratory, and echocardiographic assessment in 245 patients with heart failure (HF). All-cause mortality, cardiac transplantation, and HF hospitalization were tracked for 5 years. In our study cohort, median interquartile range MBG was 0.58 (0.38-0.81) nM. Higher MBG was associated with higher myeloperoxidase (MPO, r=0.42, p<0.0001), BNP (r=0.25, p=0.001), and asymmetric dimethylarginine (ADMA, r=0.32, p<0.001). Elevated levels of MBG were associated with measures of worse right ventricular function (RV s: r= -0.39, p<0.0001) and predicted increased risk of adverse clinical outcomes (MBG > 574 pM: HR 1.58 (1.10-2.31), p=0.014) even after adjustment for age, gender, diabetes mellitus, and ischemic etiology. In an animal validation study, a left anterior descending coronary artery ligation model of heart failure led to increases in MBG, while infusion of MBG into mice for 4 weeks led to significant increases in MPO, ADMA, and cardiac fibrosis. In the setting of heart failure, elevated plasma levels of MBG are associated with right ventricular dysfunction and predict worse long-term clinical outcomes in multivariable models adjusting for established clinical and biochemical risk factors. Infusion of MBG appears to directly contribute to increased nitrative stress and cardiac fibrosis. In our third preliminary clinical study in the junior CRF patients (n=21; 9 females and 12 males), levels of MBG progressively increased with an advancing CRF stage, reaching the highest levels at the hemodialysis stage (2.15 +/- 0.26 nM vs. 0.18 +/- 0.01 nM) compared to the healthy control. In adult CRF patients (n=12; 56+/-4 years), the level of MBG increased 3-fold vs. healthy control (n=9, age 52 +/- 5 years). Hemodialysis in adult CRF patients reduced plasma MBG concentration, but not to the control levels. Summary: These findings indicate that MBG in PE and CRF patients may be an important target for a therapeutic application of 3E9 anti-MBG mAb, which are currently in the process of humanization.