Anemia of chronic disease (ACD) is the most frequent clinical issue in patients with chronic disease. ACD is usually secondary to chronic kidney disease (CKD), cancer, and chronic infection, which is associated with poor health outcomes, increased morbidity and mortality, and substantial economic costs. Current treatment options for ACD are very limited. The discovery of the hypoxia-inducible factor-prolyl hydroxylase (HIF-PHD) pathway made it possible to develop novel therapeutic agents (such as hypoxia-inducible factor-prolyl hydroxylase inhibitor, HIF-PHI) to treat ACD by stabilizing HIF and subsequently promoting endogenous erythropoietin (EPO) production and iron absorption and utilization. Thus, HIF-PHIs appear to open a new door for the treatment of ACD patients with a novel mechanism. Here, we comprehensively reviewed the latest advancements in the application of HIF-PHIs in ACD. Specifically, we highlighted the key features of HIF-PHIs on ACD, such as stimulation of endogenous EPO, handling iron metabolism, inflammation-independent, and prolonging lifespan of red blood cells. In conclusion, the success of HIF-PHIs in the treatment of ACD may expand the therapeutic opportunity for other types of anemia beyond renal anemia.
Humans ; Anemia/metabolism* ; Chronic Disease ; Hypoxia-Inducible Factor-Proline Dioxygenases/metabolism* ; Erythropoietin/metabolism* ; Prolyl-Hydroxylase Inhibitors/therapeutic use* ; Animals ; Renal Insufficiency, Chronic

Anemia, complicating the course of chronic kidney disease, is a significant parameter, whether interpreted as subjective impairment or an objective prognostic marker. Renal anemia is predominantly due to relative erythropoietin (EPO) deficiency. EPO inhibits apoptosis of erythrocyte precursors. Studies using EPO substitution have shown that increasing hemoglobin (Hb) levels up to 10–11 g/dL is associated with clinical improvement. However, it has not been unequivocally proven that further intensification of erythropoiesis stimulating agent (ESA) therapy actually leads to a comprehensive benefit for the patient, especially as ESAs are potentially associated with increased cerebro-cardiovascular events. Recently, new developments offer interesting options not only via stimulating erythropoeisis but also by employing additional mechanisms. The inhibition of activin, a member of the transforming growth factor superfamily, has the potential to correct anemia by stimulating liberation of mature erythrocyte forms and also to mitigate disturbed mineral and bone metabolism as well. Hypoxia-inducible factor prolyl hydroxylase inhibitors also show pleiotropic effects, which are at the focus of present research and have the potential of reducing mortality. However, conventional ESAs offer an extensive body of safety evidence, against which the newer substances should be measured. Carbamylated EPO is devoid of Hb augmenting effects whilst exerting promising tissue protective properties. Additionally, the role of hepcidin antagonists is discussed. An innovative new hemodialysis blood tube system, reducing blood contact with air, conveys a totally different and innocuous option to improve renal anemia by reducing mechanical hemolysis.
Activins ; Anemia* ; Apoptosis ; Erythrocytes ; Erythropoiesis* ; Erythropoietin ; Hematinics* ; Hemolysis ; Hepcidins ; Humans ; Metabolism ; Miners ; Mortality ; Prolyl-Hydroxylase Inhibitors ; Renal Dialysis ; Renal Insufficiency, Chronic ; Transforming Growth Factors