Abstract：
The immunomodulatory effects of α-melanocyte stimulating hormone (α-MSH) in the central nervous system (CNS) have been investigated for forty years. The clinical applications of α-MSH are limited due to its short half-life. Our previous study has indicated that the short half-life of α-MSH can be extended by fusion with carrier human serum albumin (HSA) and this fusion protein has also retained the anti-inflammatory effect on the CNS. This improvement is still far from the clinical requirements. Thus, we expected to enhance the half-life and activity of the fusion protein by optimizing the linker peptide to get closer to clinical requirements. In a previous study, we screened out two candidates in vitro experiments with a flexible linker peptide (fusion protein with flexible linker peptide, FPFL) and a rigid linker peptide (fusion protein with rigid linker peptide, FPRL), respectively. However, it was not sure whether the anti-inflammatory effects in vitro could be reproduced in vivo. Our results show that FPRL is the best candidate with a longer half-life compared to the traditional flexible linker peptides. Meanwhile, the ability of FPRL to penetrate the blood-brain barrier (BBB) was enhanced, and the inhibition of TNF-α and IL-6 was improved. We also found that the toxicity of FPRL was decreased. All of the results suggested that trying to choose the rigid linker peptide in some fusion proteins may be a potential choice for improving the unsatisfactory characteristics.
摘要：
已经研究了40年的中枢神经系统（CNS）中α-黑素细胞刺激激素（α-MSH）的免疫调节作用。α-MSH的临床应用由于其半衰期短而受到限制。我们先前的研究表明，α-MSH的短半衰期可以通过与载体人血清白蛋白（HSA）融合而延长，并且该融合蛋白还保留了对CNS的抗炎作用。这种改进还远远没有达到临床的要求。因此，我们期望通过优化接头肽来提高融合蛋白的半衰期和活性,以更接近临床要求.在之前的研究中,我们在体外实验中筛选出两个具有柔性接头肽（具有柔性接头肽的融合蛋白，FPFL）和刚性接头肽（具有刚性接头肽的融合蛋白，FPRL)，分别。然而,尚不确定体外抗炎作用是否可以在体内重现。我们的结果显示,与传统的柔性接头肽相比,FPRL是具有更长半衰期的最佳候选物。同时,FPRL穿透血脑屏障（BBB）的能力增强，TNF-α和IL-6的抑制作用得到改善。我们还发现FPRL的毒性降低。所有结果表明,尝试在一些融合蛋白中选择刚性接头肽可能是改善不令人满意的特征的潜在选择。
