Skip to main content
2025 AABB Annual Meeting Main banner
Final Program


Legend
Presentation Icons
Assessor Sessions
Assessor Sessions
Committee Meetings
Committee Meetings
Foundation Events
Foundation Events
Networking Events
Networking Events
Oral Abstracts
Oral Abstracts

Plenary Oral Abstract

Cell Biology/Immunology and Biochemistry (Basic and Preclinical Research) - Red Cells

Plenary Abstract

PL1-SN-08 - Nrf2 Activation Modulates Macrophage Polarization and Reduces RBC Alloimmunization in a Transfusion Model

Sunday, October 26, 2025
10:00 AM - 11:30 AM  PT
Room: SDCC 20BC
Oral Abstracts
Background/Case Studies: Red blood cell (RBC) alloimmunization is a major challenge in transfusion medicine, particularly in sickle cell disease (SCD), where chronic inflammation exacerbates immune responses. The transcription factor nuclear factor erythroid 2–related factor 2 (Nrf2), a key regulator of oxidative stress, may play a crucial role in modulating immune responses and macrophage polarization. Macrophages display a spectrum of phenotypes, from pro-inflammatory M1 to anti-inflammatory M2 states and are the primary phagocytes of RBCs. This study investigates how Nrf2 influences macrophage polarization and regulates RBC alloimmunization, with implications for transfusion-dependent patients.

Study

Design/Methods: RhD+ RBCs from control subjects were opsonized or not with anti-RhD antibodies and co-cultured with human macrophages (hMacs) derived from blood donors. Bulk mRNA sequencing of co-cultured hMacs was performed to identify differential gene expression, which was validated by qPCR. Pharmacologic Nrf2 activation in hMacs was induced with 1-[2-cyano-3-,12-dioxooleana-1,9-dien-28-oyl]imidazole (CDDO-Im), followed by measurement of cytokines, antioxidant enzymes and polarization markers. In a murine transfusion model, CDDO-Im and the IFNα/β stimulus, poly(I:C), were administered prior to transfusion of KEL expressing RBCs to assess its impact on anti-KEL alloantibody production and post-transfusion RBC recovery. Murine bone marrow-derived macrophages (mBMDMs) were treated with CDDO-Im to assess M1/M2 gene expression. Statistical analysis included t-tests or Mann-Whitney U tests (2 groups), Kruskal-Wallis tests (≥3 groups) with Tukey's post-hoc corrections.

Results/Findings:

Bulk mRNA sequencing and qPCR showed that erythrophagocytosis of opsonized RBCs activates Nrf2 in hMacs, inducing antioxidant genes heme oxygenase 1 (HMOX1) (p< 0.01) and NQO1 (p< 0.05). Flow cytometry of co-cultured hMacs with opsonized RBCs showed increased RBC uptake by M2 compared to M1 macrophages. CDDO-Im mediated Nrf2 activation in mBMDMs promoted M2 polarization, increasing Arg-1 (p-value= 0.0229) and Ym1 (p-value= 0.0487) M2 markers, and decreasing iNOS and Mip-1α (p-value= 0.0246) M1 markers (Figure 1). In a murine transfusion model, CDDO-Im reduced anti-KEL IgG production, improved post-transfusion recovery of allogeneic RBCs, and decreased M1-related cytokines TNF and IL-6.



 


Conclusions: These findings suggest that Nrf2 activation shifts macrophage polarization in vitro to an anti-inflammatory M2 phenotype and regulates RBC alloimmunization to the KEL antigen in a pre-clinical model, providing a potential prophylactic approach to reduce alloimmunization. Further studies are needed to explore its impact in SCD and other transfusion-dependent patients.