Novel masters of erythropoiesis: hypoxia inducible factors and recent advances in anemia of renal disease

Abstract

Anemia seen in patients with chronic kidney disease is a particular form of ‘anemia of chronic disease'. Although multifactorial in origin, erythropoiesis-stimulating agents (ESAs) and adjuvant iron therapy represent the primary treatment for anemia in chronic kidney disease. Subsequent clinical observations revealed that these ESA hyporesponsive patients often had increased systemic inflammation as a consequence of their comorbidities. Use of high ESA doses to overcome this ESA hyporesponsiveness posed some concerns regarding associated adverse events of therapy and increased mortality in this special patient population. Recognizing the pivotal roles of hypoxia inducible factors (HIFs) in orchestrating elements of erythropoiesis opened new avenues in the management of renal anemia. Several phase 1 and 2 studies confirmed the results of early experimental studies supporting the beneficial role of augmenting HIFs for erythropoiesis. In this review, we describe the physiologic functions of HIF in erythropoiesis with special emphasis on interactions with iron and hepcidin metabolism and inflammation.