Controversial Impact of Hepcidin Metabolism in the Pathogenesis of Anemia in Myelofibrosis

Abstract

Anemia in myelofibrosis (MF) is a result of a multifactorial process, which is incompletely understood. The central pathogenetic mechanism is a replacement of normal hemopoietic tissue by fibrotic stroma. However, ineffective erythropoiesis, inflammation and iron overload have an additional impact on anemia development, suggesting the role of dysregulated iron homeostasis and hepcidin. The aim of the study was to analyze parameters of iron metabolism and inflammation in patients with different forms and stages of myelofibrosis. Thirty-six patients with primary MF, post-polycythemia vera and post-essential thrombocythemia MF and fourteen healthy controls were included in the study. In the patient group, serum ferritin, Fe, TIBC and parameters of CBC were measured as a part of routine clinical assessment. Plasma total hepcidin levels and concentrations of Interleukin-6 (IL6) and Interleukin-8 (IL8) were measured in duplicate by ELISA (My BioSource, San Diego, USA) in patients and healthy controls. The hepcidin level in the patient group was found statistically lower compared to healthy controls (27,64±41,56 ng/ml; 111,13±49,56 ng/ml; F=2,81, p<0,001). Patients with newly diagnosed MF had significantly higher levels of hepcidin compared to those with prolonged evolution: between 1 and 5 years (p=0,005) and >5 years (p=0,038). Transfusion dependent patients presented with lower hepcidin compared to transfusions independent (10,10±6,67 ng/ml; 31,15±44,37 ng/ml; p=0,026). In patients receiving cytoreductive or target treatment hepcidin level was significantly lower compared to patients on best supportive care (17,74±21,99 ng/ml; 43,05±58,46 ng/ml; p=0,037). No difference was found in hepcidin level within the risk groups according to DIPSS, neither between the subtypes of disease (primary MF and secondary MF). Higher hepcidin positively correlated with leukocytosis (R=0,665, p=0,009) and age (R=0,392, p=0,0081). By multivariate analysis, a significant highly positive correlation was found between hepcidin and IL-6 (R=0,535, p=0,002) and weaker between hepcidin and IL-8 (R=0,413, p=0,21) A significant straight correlation was demonstrated between IL-6 and IL-8 (R=0,464, p=0,009) and a negative between serum iron and IL-6 (R=-0,367, p=0,42) and IL-8 (R=-0,438, p=0,14), respectively. The hepcidin regulation is complex and multifactorial. Its role in pathogenesis of anemia in myelofibrosis is controversary. Probably it has a higher impact in early stages of the disease and depends on treatment and transfusions.