Gene transfer for the cure of ß-thalassemia and sickle cell anemia. Beta-thalassemia and sickle cell anemia (SCD) represent the most common hemoglobinopathies caused, respectively, by deficient production or alteration of the hemoglobin beta-chain subunit. We are generating gene-delivering tools for the cure of these disorders. Our approaches are based on achieving therapeutic levels of corrective genes (beta-globin and/or gamma globin) following gene transfer or use of drugs that modify the splicing of beta-globin RNA mutant forms. We are also developing new strategies to introduce genetically modified cells into the bone marrow with minimal conditioning.
Erythropoiesis and iron metabolism in beta-thalassemia, hemochromatosis and polycythemia vera. Progressive iron overload is the most salient and ultimately fatal complication of beta-thalassemia. The hepatic peptide hepcidin limits iron absorption and recycling, degrading the iron exporter ferroportin at the level of enterocytes and macrophages. In beta-thalassemia, ineffective erythropoiesis represses hepcidin, leading to iron overload. Therefore, we hypothesized that increased expression of hepcidin reduces iron burden in beta-thalassemia. In fact, we showed that increased levels of hepcidin prevent iron overload and ameliorate the anemia in animals affected by beta-thalassemia. Our findings might also have an impact on the treatment of hemochromatosis and polycythemia vera.
Ineffective erythropoiesis in ß-thalassemia and MDS. In patients affected by ß-thalassemia there is an excessive production of immature erythroid cells. Our study suggests that erythropoiesis in beta-thalassemia is characterized by enhanced expression of genes that promote cell cycle and survival, such as erythropoietin (EPO) and JAK2, or that control EPO synthesis, such as HIF2alpha. We are now studying the role of these proteins in this disorder and characterizing new therapeutics that modulate EPO synthesis as well as inhibit HIF2alpha or JAK2 activity. For instance, we showed that use of JAK2 inhibitors is effective in limiting ineffective erythropoiesis, extramedullary erythropoiesis and in reversing splenomegaly. We are further investigating the use of these compounds and are characterizing additional erythroid related genes (such as GDF11 and SMADs) that are deregulated in this disorder. We are also investigating these compounds and mechanisms in myelodysplastic syndromes (MDS).
The role of macrophages in normal and diseased erythropoiesis. Macrophages represent an important link between erythropoiesis and iron metabolism. They support maturation and differentiation of erythroblasts and clear senescent red cells from circulation, thus recycling iron within the hematopoietic system. However, little is known about the role of macrophages in conditions of chronic stress erythropoiesis like in polycythemia vera and beta-thalassemia. Our observations suggest that macrophages have a crucial function related to chronic stress erythropoiesis. In fact, modulation of their activity leads to profound and beneficial effects in these two disorders. Our goal is to characterize the relationship between macrophages and erythroid cells under condition of chronic stress erythropoiesis.
Characterization of iron metabolism and erythropoiesis in inflammation and anemia. Hepcidin, through interleukin-6 and other cytokines, might be upregulated in many inflammatory disorders, including some forms of cancer. High levels of hepcidin limit iron absorption and sequester iron in the macrophages, leading to reduced red cell production and anemia. Many inflammatory cytokines impair erythroid proliferation. We are actively investigating this process, focusing on the role of interleukin-6, tumor necrosis factor, interferon-gamma and other cytokines in a variety of conditions, including anemia of inflammation (AI), inflammatory bowel disease (IBD) and chronic kidney disease (CKD).