HB reduces inflammation in HUVECs via the Nrf2/HO-1 axis by inhabiting apoptosis and oxidative stress

Existing research data indicate that Hemoglobin (HB) can ameliorate oxidative stress, fibrosis, and inflammatory responses. Given that traditional cardiovascular and cerebrovascular diseases are associated with chronic vascular injury and oxidative stress, this study aimed to investigate the effect of HB on vascular inflammation and explore its potential for vascular protection. The study employed the CCK-8 assay, Western blot, immunofluorescence, PCR, as well as assessments of reactive oxygen species (ROS), malondialdehyde (MDA), Caspase-3 activity, and flow cytometry. Apoptosis was detected by flow cytometry using Annexin V-FITC staining, and intracellular reactive oxygen species (ROS) levels were measured using the fluorescent probe DCFDA-DA. HB significantly reduced the expression of inflammatory cytokines (TNF‑α, IL‑6, IL‑1β) in H₂O₂‑stimulated HUVECs, an effect associated with attenuation of oxidative stress‑induced inflammatory responses, and reduced levels of MDA, ROS, and vascular cell apoptosis. These effects were mediated through enhancing Nrf2/HO‑1 pathway expression and function. When the Nrf2/HO‑1 pathway was inhibited, the suppressive effects of HB on inflammatory markers and vascular oxidative stress were markedly attenuated. These findings suggest that HB enhances Nrf2/HO‑1 expression and function and that this pathway contributes to the protective effects of HB to reduce inflammatory cytokine release, oxidative stress, and apoptosis in H₂O₂-stimulated HUVECs. HB's anti‑inflammatory effects are secondary to the attenuation of oxidative stress. These findings extend the known antioxidant properties of HB to the vascular endothelium, supporting further investigation in the context of oxidative stress‑induced endothelial dysfunction.