Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
FASEB J. 2022 Apr;36(4):e22267. doi: 10.1096/fj.202200052R.
Peroxiredoxin-2 (Prx-2) is a critical antioxidant protein in red blood cells (RBC). Prx-2 is oxidized to a disulfide covalently-bound dimer by H O , and then reduced back by the NADPH-dependent thioredoxin-thioredoxin reductase system. The reduction of oxidized Prx-2 is relatively slow in RBCs. Since Prx-2 is highly abundant, Prx-2s' peroxidase catalytic cycle is not considered to be limiting under normal conditions. However, whether Prx-2 recycling becomes limiting when RBCs are exposed to stress is not known. Using three different model systems characterized by increased oxidative damage to RBCs spanning the physiologic (endogenous RBCs of different ages), therapeutic (cold-stored RBCs in blood banks) and pathologic (RBCs from sickle cell disease (SCD) patients and humanized SCD mice) spectrum, basal levels of Prx-2 oxidation and Prx-2 recycling kinetics after addition of H O were determined. The reduction of oxidized Prx-2 was significantly slower in older versuin older versus younger RBCs, in RBCs stored for 4-5 weeks compared to 1 week, and in RBC from pediatric SCD patients compared to RBCs from control non-SCD patients. Similarly, the rate of Prx-2 recycling was slower in humanized SCD mice compared to WT mice. Treatment of RBC with carbon monoxide (CO) to limit heme-peroxidase activity had no effect on Prx-2 recycling kinetics. Treatment with glucose attenuated slowed Prx-2 recycling in older RBCs and SCD RBCs, but not stored RBCs. In conclusion, the reduction of oxidized Prx-2 can be further slowed in RBCs, which may limit the protection afforded by this antioxidant protein in settings associated with erythrocyte stress.
过氧化物酶 2（Prx-2）是红细胞（RBC）中一种重要的抗氧化蛋白。Prx-2 被 H2O2 氧化为二硫键共价结合的二聚体，然后被 NADPH 依赖的硫氧还蛋白-硫氧还蛋白还原酶系统还原。在 RBC 中，氧化的 Prx-2 的还原相对较慢。由于 Prx-2 含量丰富，因此在正常条件下，Prx-2 的过氧化物酶催化循环不被认为是有限的。然而，当 RBC 暴露于应激时，Prx-2 的回收是否受到限制尚不清楚。使用三种不同的模型系统，这些模型系统的特点是 RBC 受到的氧化损伤增加，涵盖了生理范围（不同年龄的内源性 RBC）、治疗范围（血库中的冷藏 RBC）和病理范围（镰状细胞病（SCD）患者和人源化 SCD 小鼠的 RBC），测定了添加 H2O2 后 Prx-2 氧化和 Prx-2 回收动力学的基础水平。与年轻 RBC 相比，老年 RBC 的 Prx-2 氧化还原水平明显较低，与储存 4-5 周的 RBC 相比，储存 1 周的 RBC 更低，与来自对照非 SCD 患者的 RBC 相比，儿科 SCD 患者的 RBC 更低。同样，人源化 SCD 小鼠的 Prx-2 回收速率也比 WT 小鼠慢。用一氧化碳（CO）处理 RBC 以限制血红素过氧化物酶活性对 Prx-2 回收动力学没有影响。用葡萄糖处理可减弱老年 RBC 和 SCD RBC 中 Prx-2 回收的缓慢，但不能减弱储存 RBC 中 Prx-2 回收的缓慢。总之，RBC 中氧化的 Prx-2 的还原速度可以进一步减慢，这可能会限制这种抗氧化蛋白在与红细胞应激相关的环境中提供的保护。
