Institute of Molecular Virology, Ulm University Medical Center, 89081, Ulm, Germany.
German Red Cross Blood Donor Service Baden-Wuerttemberg-Hessen, Institute Frankfurt, 60528, Frankfurt, Germany.
J Transl Med. 2021 May 3;19(1):190. doi: 10.1186/s12967-021-02859-6.
Endogenous Peptide Inhibitor of CXCR4 (EPI-X4) is a natural antagonist of the CXC chemokine receptor 4 (CXCR4). EPI-X4 is a 16-mer peptide that is released from human serum albumin (HSA) by acidic aspartic proteases such as Cathepsin D and E. Since human serum albumin (HSA) is an important medicinal substance we asked whether different pharmaceutical HSA products contain EPI-X4 which could have been generated during manufacturing and whether HSA can serve as a substrate for cathepsins despite of the presence of stabilizers like caprylate.
Eight pharmaceutical HSA preparations representing all currently used fractionation technologies were analyzed. The previously described specific EPI-X4 ELISA was used for quantification; in vitro EPI-X4 generation by acidification in the presence or absence of cathepsins was followed by quantification with ELISA.
None of the pharmaceutical HSA preparations tested contained EPI-X4. Acidification of HSA did not generate EPI-X4. Addition of cathepsins D and E to acidified HSA yielded high concentrations of EPI-X4 in all HSA preparations, indistinguishable between individual products.
Medicinal HSA preparations per se do not contain EPI-X4, but will replenish its precursor which can be cleaved to EPI-X4 in vivo, environmental conditions permitting.
内源性 CXCR4 趋化因子受体（EPI-X4）抑制剂是 CXC 趋化因子受体 4（CXCR4）的天然拮抗剂。EPI-X4 是一种 16 肽，可通过酸性天冬氨酸蛋白酶（如组织蛋白酶 D 和 E）从人血清白蛋白（HSA）中释放出来。由于人血清白蛋白（HSA）是一种重要的药用物质，我们询问了不同的药用 HSA 产品是否含有在制造过程中产生的 EPI-X4，以及 HSA 是否可以作为组织蛋白酶的底物，尽管存在稳定剂如辛酸。
分析了代表所有当前使用的分级技术的八种药用 HSA 制剂。使用先前描述的特异性 EPI-X4 ELISA 进行定量；通过在存在或不存在组织蛋白酶的情况下酸化来进行体外 EPI-X4 生成，并通过 ELISA 进行定量。
测试的八种药用 HSA 制剂均未含有 EPI-X4。HSA 的酸化没有产生 EPI-X4。将组织蛋白酶 D 和 E 添加到酸化的 HSA 中，在所有 HSA 制剂中产生了高浓度的 EPI-X4，在各个产品之间没有区别。
药用 HSA 制剂本身不含 EPI-X4，但在环境条件允许的情况下，会补充其前体，可在体内被切割为 EPI-X4。
