A New Murine Model of Primary Autoimmune Hemolytic Anemia (AIHA).

Flavia Dei Zotti,Francesca La Carpia,Krystalyn E Hudson,Annie Qiu,Chiara Moriconi

doi:10.3389/fimmu.2021.752330

Abstract

Loss of humoral tolerance to red blood cells (RBCs) can lead to autoimmune hemolytic anemia (AIHA), a severe, and sometimes fatal disease. Patients with AIHA present with pallor, fatigue, decreased hematocrit, and splenomegaly. While secondary AIHA is associated with lymphoproliferative disorders, infections, and more recently, as an adverse event secondary to cancer immunotherapy, the etiology of primary AIHA is unknown. Several therapeutic strategies are available; however, there are currently no licensed treatments for AIHA and few therapeutics offer treatment-free durable remission. Moreover, supportive care with RBC transfusions can be challenging as most autoantibodies are directed against ubiquitous RBC antigens; thus, virtually all RBC donor units are incompatible. Given the severity of AIHA and the lack of treatment options, understanding the cellular and molecular mechanisms that facilitate the breakdown in tolerance would provide insight into new therapeutics. Herein, we report a new murine model of primary AIHA that reflects the biology observed in patients with primary AIHA. Production of anti-erythrocyte autoantibodies correlated with sex and age, and led to RBC antigen modulation, complement fixation, and anemia, as determined by decreased hematocrit and hemoglobin values and increased reticulocytes in peripheral blood. Moreover, autoantibody-producing animals developed splenomegaly, with altered splenic architecture characterized by expanded white pulp areas and nearly diminished red pulp areas. Additional analysis suggested that compensatory extramedullary erythropoiesis occurred as there were increased frequencies of RBC progenitors detectable in the spleen. No significant correlations between AIHA onset and inflammatory status or microbiome were observed. To our knowledge, this is the first report of a murine model that replicates observations made in humans with idiopathic AIHA. Thus, this is a tractable murine model of AIHA that can serve as a platform to identify key cellular and molecular pathways that are compromised, thereby leading to autoantibody formation, as well as testing new therapeutics and management strategies.

Highlights

Autoimmune hemolytic anemia (AIHA) is a disorder characterized by destruction of red blood cells (RBCs) by pathogenic anti-erythrocyte autoantibodies
To study how red blood cell (RBC)-specific T cell tolerance is established and to identify which pathways are compromised when autoimmune disease develops, we generated a murine model of primary autoimmune hemolytic anemia (AIHA) by breeding HOD and OTII mice (HODxOTII F1 animals which included HOD+OTII+ autoimmune genotype and HOD-OTII+ non-autoimmune genotype littermate control animals) (Figure 1A)
Sera was collected monthly from HODxOTII F1 animals and evaluated for production of detectable HOD RBC antibodies by flow crossmatch (Figure 1B)

Summary

Introduction

Autoimmune hemolytic anemia (AIHA) is a disorder characterized by destruction of red blood cells (RBCs) by pathogenic anti-erythrocyte autoantibodies. Elucidation of the initiating events that lead to development of AIHA have relied on both observations in human AIHA patients and murine models. With these studies, breakdown of tolerance to RBC autoantigens has been shown to be multifactorial (e.g., genetics as observed in NZB mice, immune dysregulation as demonstrated in the Playfair and Marshall-Clarke model, etc.) [13, 14]. Despite several AIHA murine models, one barrier to elucidating the initiating events leading to the failure of RBC tolerance is the lack of a model that accurately reflects primary AIHA

Methods

Results

Conclusion