Anemia in Hodgkin Lymphoma: The Role of Interleukin-6 and Hepcidin.

Abstract 3656

Poster Board III-592

Anemia is present at diagnosis in approximately 40% of patients with Hodgkin lymphoma (HL). The anemia is typically the normochromic, normocytic anemia of chronic disease seen in a wide variety of inflammatory states. It is more commonly observed in advanced stages of disease and when B-symptoms are present. Local production of cytokines by the Hodgkin and Reed-Sternberg cells and the surrounding microenvironment are supposed to mediate the systemic inflammatory reactions. Studies in humans and mice suggest that the liver-produced acute-phase peptide hepcidin is the principal regulator of extracellular iron concentration and may be the principal mediator of anemia of chronic disease and/or inflammation. As IL-6 is a potent inducer of hepcidin expression, we studied the role of hepcidin in HL analyzing for correlations between plasma hepcidin levels, cytokine levels, parameters of inflammation, iron metabolism and patient characteristics. We studied 65 patients with HL at diagnosis. Anemia defined as hemoglobin level <12 g/dl was present in 31 patients. Hemoglobin levels were lower in female patients, patients with age > 45 years, in the presence of B-symptoms, stage IV disease and with a higher IPS score (> 2). Plasma samples at diagnosis were analyzed for levels of the cytokines IL-6, IL-10, and the chemokine TARC using ELISA techniques (R&D Dignostics), while hepcidin levels were determined using a combination of weak cation exchange chromatography and time-of-flight mass spectrometry (TOF MS), as described previously (Swinkels et al, PLOS ONE 2008; 3:e2706). The mean hepcidin level was 7.9 nmol/L, ranging from below the detection limit of 0.5 nmol/l in 3 patients to 27.4 nM. Hepcidin levels were higher in patients aged over 45 years (p=0.03), and there was a borderline significance for higher hepcidin levels in male patients in comparison with females (p=0.06). In anemic patients hepcidin levels inversely correlated with haemoglobin values (r=-0.45, p=0.01). We found a highly significant correlation between levels of hepcidin and IL-6 (r=0.55, p=0.0001). IL-6 was elevated in 40/55 patients, and IL-6 inversely correlated with haemoglobin values (r=-0.49, p=0.0001). No significant correlation was observed between IL-10 or TARC levels and hepcidin arguing against a role for these cytokines in hepcidin up-regulation in HL patients. The analysis of hepcidin with parameters of iron metabolism in patients with HL showed significant correlations with ferritin (r=0.62, p= 0.0001), while iron and iron-binding capacity inversely correlated with hepcidin (r=-0.42, p=0.009; and r=-0.43, p=0.02, respectively). Increases in serum ferritin, low serum iron and reduced iron-binding capacity are characteristic for anemia of chronic disease. In a multivariate regression analysis, IL-6 and ferritin levels independently correlated with hepcidin (p=0.003 and p=0.02, respectively), while haemoglobin levels were not independently associated with hepcidin in this model. Hepcidin levels were significantly associated with stage IV disease (p=0.01), the presence of B-symptoms (p=0.03), and IPS score > 2 (p=0.005). In conclusion, our findings support the hypothesis, that in HL elevated levels of circulating IL-6 are associated with upregulation of hepcidin, resulting in hypoferremia and development of anemia with the typical signs of anemia of chronic disease. In addition, associations of hepcidin levels with patient characteristics of prognostic significance suggest that hepcidin should be studied as a new potential biomarker in HL.