Apohemoglobin-haptoglobin complex alleviates iron toxicity in mice with β-thalassemia via scavenging of cell-free hemoglobin and heme

Abstract

β-thalassemia is a genetic hemoglobin (Hb) disorder that affects millions of people world-wide. It is characterized by ineffective erythropoiesis and anemia. The resultant chronic anemia can require life-long blood transfusion regimens, leading to secondary hemochromatosis. Moreover, the abnormal red blood cells (RBCs) from β-thalassemia patients are prone to hemolytic events that release cell-free Hb and heme causing a series of events that result in oxidative organ and tissue damage. In this study, β-thalassemic mice were treated with a protein scavenger for six weeks, apohemoglobin-haptoglobin (apoHb-Hp), this protein scavenges cell free Hb and heme. We hypothesize that scavenging cell-free Hb and heme will lead to a positive therapeutic event. After the apoHb-hp treatment it was observed to reduce the weight of the liver and spleen and show an improvement in liver function by a drop in ALT, AST, and ALP markers. ApoHb-hp treatment also hints at an improved RBC half-life as the number of reticulocytes decreased, the mean corpuscular volume (MCV) increased, mean corpuscular hemoglobin increase and the RBC distribution width decreased. Furthermore, apoHb-Hp treatment reduced circulating serum iron concentration and transferrin saturation concentration. Based on these outcomes, introducing a scavenger protein can benefit β-thalassemic mice. This study demonstrated that apoHb-Hp treatment may be a viable strategy to mitigate toxicities associated with cell free Hb and heme, a driver of β-thalassemic issues.

Keywords

• Apohemoglobin
• Haptoglobin
• Iron toxicity
• Thalassemia
• Anemia
• Hemolysis