Hemoglobin-based oxygen carriers promote the expression of antiviral defense genes in bone marrow leukocytes.

Hemoglobin-based oxygen carriers (HBOCs) are blood substitutes utilized for oxygen delivery, but their systemic effects on immune homeostasis remain insufficiently characterized. In this study, healthy C57BL/6J mice were intravenously administered with either HBOC (RedpCarrier, 600 mg/kg/day) or vehicle for three consecutive days. Using single-cell RNA sequencing (scRNA-seq), we generated a comprehensive transcriptomic atlas of bone marrow (BM) leukocytes. Unbiased clustering revealed that HBOC exposure significantly remodeled the BM landscape, characterized by a proportional decrease in neutrophils and monocytes alongside an expansion of B cells, T cells, and dendritic cells. Quantitative analysis identified 124 significantly upregulated genes across immune compartments, which were overwhelmingly enriched in Type-I interferon signaling and defense responses to viruses. The interferon-stimulated gene Isg15 was identified as a core upregulated marker across multiple lineages. To evaluate functional outcomes, we employed lethal SARS-CoV-2 and HSV-1 infection models, where HBOC-pretreated mice exhibited significantly higher 14-day survival rates compared to controls. In summary, our findings demonstrate that HBOC administration induces a distinctive antiviral-like transcriptional priming state within the bone marrow microenvironment. Crucially, in vitro functional assays and protein-level validations confirm that high-dose HBOC treatment drives intracellular ROS accumulation and subsequently activates Stat1 expression and phosphorylation in macrophages. Together, these transcriptomic and experimental insights establish a solid mechanistic link between HBOC-induced redox modulation and innate immune activation, providing a foundational framework for exploring HBOCs as potential adjunctive immunomodulators for enhanced viral defense.