Corbin John A, Bhaskar Vinay, Goldfine Ira D, Bedinger Daniel H, Lau Angela, Michelson Kristen, Gross Lisa M, Maddux Betty A, Kuan Hua F, Tran Catarina, Lao Llewelyn, Handa Masahisa, Watson Susan R, Narasimha Ajay J, Zhu Shirley, Levy Raphael, Webster Lynn, Wijesuriya Sujeewa D, Liu Naichi, Wu Xiaorong, Chemla-Vogel David, Lee Steve R, Wong Steve, Wilcock Diane, White Mark L
Department of Preclinical Research, XOMA Corporation, Berkeley, California, United States of America.
Department of Medicine, University of California San Francisco, San Francisco, California, United States of America.
PLoS One. 2014 Feb 12;9(2):e88684. doi: 10.1371/journal.pone.0088684. eCollection 2014.
Previously we reported studies of XMetA, an agonist antibody to the insulin receptor (INSR). We have now utilized phage display to identify XMetS, a novel monoclonal antibody to the INSR. Biophysical studies demonstrated that XMetS bound to the human and mouse INSR with picomolar affinity. Unlike monoclonal antibody XMetA, XMetS alone had little or no agonist effect on the INSR. However, XMetS was a strong positive allosteric modulator of the INSR that increased the binding affinity for insulin nearly 20-fold. XMetS potentiated insulin-stimulated INSR signaling ∼15-fold or greater including; autophosphorylation of the INSR, phosphorylation of Akt, a major enzyme in the metabolic pathway, and phosphorylation of Erk, a major enzyme in the growth pathway. The enhanced signaling effects of XMetS were more pronounced with Akt than with Erk. In cultured cells, XMetS also enhanced insulin-stimulated glucose transport. In contrast to its effects on the INSR, XMetS did not potentiate IGF-1 activation of the IGF-1 receptor. We studied the effect of XMetS treatment in two mouse models of insulin resistance and diabetes. The first was the diet induced obesity mouse, a hyperinsulinemic, insulin resistant animal, and the second was the multi-low dose streptozotocin/high-fat diet mouse, an insulinopenic, insulin resistant animal. In both models, XMetS normalized fasting blood glucose levels and glucose tolerance. In concert with its ability to potentiate insulin action at the INSR, XMetS reduced insulin and C-peptide levels in both mouse models. XMetS improved the response to exogenous insulin without causing hypoglycemia. These data indicate that an allosteric monoclonal antibody can be generated that markedly enhances the binding affinity of insulin to the INSR. These data also suggest that an INSR monoclonal antibody with these characteristics may have the potential to both improve glucose metabolism in insulinopenic type 2 diabetes mellitus and correct compensatory hyperinsulinism in insulin resistant conditions.
此前我们报道了对XMetA（一种胰岛素受体（INSR）激动剂抗体）的研究。我们现在利用噬菌体展示技术鉴定出了XMetS，一种新型的INSR单克隆抗体。生物物理研究表明，XMetS以皮摩尔亲和力与人及小鼠的INSR结合。与单克隆抗体XMetA不同，单独的XMetS对INSR几乎没有激动作用。然而，XMetS是INSR的一种强效正变构调节剂，可使胰岛素的结合亲和力增加近20倍。XMetS增强胰岛素刺激的INSR信号传导约15倍或更高，包括：INSR的自磷酸化、代谢途径中的主要酶Akt的磷酸化以及生长途径中的主要酶Erk的磷酸化。XMetS增强的信号传导作用对Akt比对Erk更明显。在培养细胞中，XMetS还增强了胰岛素刺激的葡萄糖转运。与其对INSR的作用相反，XMetS不能增强IGF-1对IGF-1受体的激活作用。我们研究了XMetS治疗在两种胰岛素抵抗和糖尿病小鼠模型中的效果。第一种是饮食诱导肥胖小鼠，一种高胰岛素血症、胰岛素抵抗的动物，第二种是多次低剂量链脲佐菌素/高脂肪饮食小鼠，一种胰岛素缺乏、胰岛素抵抗的动物。在这两种模型中，XMetS均使空腹血糖水平和葡萄糖耐量恢复正常。与其增强INSR处胰岛素作用的能力相一致，XMetS在两种小鼠模型中均降低了胰岛素和C肽水平。XMetS改善了对外源性胰岛素的反应而不引起低血糖。这些数据表明，可以产生一种变构单克隆抗体，其可显著增强胰岛素与INSR的结合亲和力。这些数据还表明，具有这些特性的INSR单克隆抗体可能有潜力改善胰岛素缺乏型2型糖尿病中的葡萄糖代谢，并纠正胰岛素抵抗状态下的代偿性高胰岛素血症。
