Hydrogen peroxide diffusion across the red blood cell membrane occurs mainly by simple diffusion through the lipid fraction

Hydrogen peroxide (H2O2) is an oxidant produced endogenously by several enzymatic pathways. While it can cause molecular damage, H2O2 also plays a role in regulating cell proliferation and survival through redox signaling pathways. In the vascular system, red blood cells (RBCs) are notably efficient at metabolizing H2O2. In addition to a robust antioxidant defense, we recently determined that human RBCs also have a high membrane permeability to H2O2 that is independent of aquaporin 1 or aquaporin 3. In this work, we sought to further investigate the permeation mechanism of H2O2 through the membrane of human RBCs. First, we explored the role of other erythrocytic membrane proteins in H2O2 transport, including urea transporter B and ammonia transporter Rh proteins. However, no differences were found in H2O2 permeability in RBCs lacking these proteins compared to control RBCs. We then focused on the hypothesis that H2O2 diffuses through the lipid bilayer. To test this, we studied H2O2 permeability in RBCs from patients with Gaucher disease (GD), which accumulate sphingolipids in the membrane, affecting RBC morphology and deformability. We found that RBCs from GD patients exhibited lower H₂O₂ membrane permeability. In another approach, we treated normal RBCs with hexanol, which fluidizes the lipid fraction of the RBC membrane, and observed an increase in the permeability to H2O2. In contrast, hexanol had no effect on the rate of water efflux by aquaporin 1. Together, these results support the hypothesis that H2O2 diffusion through the RBC membrane occurs primarily through the lipid fraction. [Display omitted] •Red blood cells (RBC) efficiently decompose external H2O2.•The diffusion mechanism of H2O2 across the membrane is poorly understood.•Neither urea nor ammonia transporters facilitate H2O2 diffusion.•Alterations in the RBC lipids affect H2O2 diffusion.•Evidence indicates that H2O2 permeates the RBC membrane by simple diffusion.