Activated macrophages induce hepcidin expression in HuH7 hepatoma cells

Background

Hepcidin is an iron regulatory peptide produced by the liver in response to inflammation and elevated systemic iron. Recent studies suggest that circulating monocytes and resident liver macrophages – Küpffer cells – may influence both basal and inflammatory expression of hepcidin.

Design and Methods

We used an in vitro co-culture model to investigate hepatocyte hepcidin regulation in the presence of activated THP1 macrophages. HuH7 hepatoma cells were co-cultured with differentiated THP1 macrophages for 24 h prior to the measurement of HuH7 hepcidin (HAMP) mRNA expression using quantitative polymerase chain reaction, and HAMP promoter activity using a luciferase reporter assay. Luciferase assays were performed using the wild type HAMP promoter, and constructs containing mutations in BMP/SMAD4, STAT3, C/EBP and E-BOX response elements. Neutralizing antibodies against interleukin-6, interleukin-1β , and the bone morphogenetic protein inhibitor noggin were used to identify the macrophage-derived cytokines involved in the regulation of HAMP expression.

Results

Co-culturing HuH7 cells with differentiated THP1 cells induced HAMP promoter activity and endogenous HAMP mRNA expression maximally after 24 h. This induction was fully neutralized in the presence of an interleukin-1β antibody, and fully attenuated by mutations of the proximal C/EBP or BMP/SMAD4 response elements.

Conclusions

Our data suggest that the interleukin-1β and bone morphogenetic protein signaling pathways are central to the regulation of HAMP expression by macrophages in this co-culture model.     

Mild increases in serum hepcidin and interleukin-6 concentrations impair iron incorporation in haemoglobin during an experimental human malaria infection

The correct selection of individuals who will benefit from iron supplements in malaria-endemic regions requires improved insight in the effects of malaria on host iron homeostasis and innovative biomarkers. We assessed sequential changes in serum hepcidin and in traditional biochemical iron status indicators during an experimental Plasmodium falciparum malaria infection with five adult volunteers. The haemoglobin content of reticulocytes (Ret-H_e) and of mature red blood cells (RBC-H_e) represented iron incorporation into haemoglobin. Low-density parasitaemia and its treatment induced a mild increase in interleukin (IL)-6 and serum hepcidin concentrations. Despite this only mild increase, a marked hypoferraemia with a strong increase in serum ferritin concentrations developed, which was associated with a sharp fall in Ret-H_e, while RBC-H_e remained unchanged. The ratio of soluble transferrin receptor (sTfR) to log ferritin concentrations decreased to an average nadir of 63% of the baseline value. We concluded that even mild increases in serum hepcidin and IL-6 concentrations result in a disturbed host iron homeostasis. Serum hepcidin, Ret-H_e and Delta-H_e (Ret-H_e minus RBC-H_e) are promising biomarkers to select those individuals who will benefit from iron supplements in malaria endemic regions, while the sTfR/log ferritin ratio should be used with caution to assess iron status during malaria.     

Downregulation of hepcidin and haemojuvelin expression in the hepatocyte cell-line HepG2 induced by thalassaemic sera

Beta-thalassaemia represents a group of diseases, in which ineffective erythropoiesis is accompanied by iron overload. In a mouse model of beta-thalassaemia, we observed that the liver expressed relatively low levels of hepcidin, which is a key factor in the regulation of iron absorption by the gut and of iron recycling by the reticuloendothelial system. It was hypothesised that, despite the overt iron overload, a putative plasma factor found in beta-thalassaemia might suppress liver hepcidin expression. Sera from beta-thalassaemia and haemochromatosis (C282Y mutation) patients were compared with those of healthy individuals regarding their capacity to induce changes the expression of key genes of iron metabolism in human HepG2 hepatoma cells. Sera from beta-thalassaemia major patients induced a major decrease in hepcidin (HAMP) and lipocalin2 (oncogene 24p3) (LCN2) expression, as well as a moderate decrease in haemojuvelin (HFE2) expression, compared with sera from healthy individuals. A significant correlation was found between the degree of downregulation of HAMP and HFE2 induced by beta-thalassaemia major sera (r = 0.852, P < 0.0009). Decreased HAMP expression was also found in HepG2 cells treated with sera from beta-thalassaemia intermedia patients. In contrast, the majority of sera from hereditary haemochromatosis patients induced an increase in HAMP expression, which correlated with transferrin (Tf) saturation (r = 0.765, P < 0.0099). Our results suggest that, in beta-thalassaemia, serum factors might override the potential effect of iron overload on HAMP expression, thereby providing an explanation for the failure to arrest excessive intestinal iron absorption in these patients.     

Iron metabolism in athletes – achieving a gold standard

Iron is an important mineral element required for diverse life processes. Its metabolism is almost synonymous to erythrocyte maintenance, erythropoiesis and erythrophagocytosis. Consequently, exercise exertion impacts significantly on red cell haematology. Here, the interactions between exercise and erythropoiesis are explored. Hepcidin, the peptide hormone that regulates systemic iron metabolism, decreases in response to erythropoiesis by facilitating increased iron efflux from ferroportin into circulation. However, during exercise, there is an alarming increase in the expression of hepcidin resulting in a negative iron balance in athletes. In this review, the confounding cause and effect scenarios of exercise, athlete training and haematology and hepcidin interactions are discussed.     

骨形态发生蛋白与肿瘤

骨形态发生蛋白(bone morphogenetic proteins,BMPs)是属于转化生长因子-β超家族的一类细胞因子,在骨转化、胚胎发育及正常组织、器官的动态平衡生长中发挥重要作用。最近研究表明,BMPs及其受体一方面可通过参与肿瘤的增殖,转移,血管生成以及分化等促进肿瘤发生发展; 另一方面,却可通过上述作用成为肿瘤细胞的抑制分子。     

The links of hepcidin and erythropoietin in the interplay of inflammation and iron deficiency in a large observational study of rheumatoid arthritis

Anaemia affects quality of life and radiographic outcome in rheumatoid arthritis (RA). In a cross-sectional study with 779 patients, we assessed the prognostic potential of the major haematopoietic regulators, hepcidin and erythropoietin, comparing their serum concentrations with respect to different anaemia types, inflammatory activity, anti-cytokine-specific treatment effects and iron deficiency (ID) indices. The results showed that clinical disease activity was more closely associated with haemoglobin levels than with anti-tumour necrosis factor-alpha or interleukin 6 receptor effects. In ID, hepcidin was suppressed, independently of inflammation. Erythropoietin levels were inappropriately low in relation to the degree of anaemia, but, in contrast to low haemoglobin, not directly associated with joint damage progression. Hepcidin and erythropoietin levels are intimately connected with inflammation and ID. Interventional studies on these important targets are already in progress.     

Hepcidin and ferroportin expression in breast cancer tissue and serum and their relationship with anemia

ObjectiveOur correlation study investigated the relationships of the expression of hepcidin and ferroportin (fpn) in tissues and serum from breast cancer (bca) patients and the relationships of hepcidin and fpn with anemia.MethodsWe used elisa and immunohistochemistry to detect the expression of hepcidin and fpn in tissue and serum from 62 individuals with bca, and we analyzed correlations between hepcidin and fpn expression in tissue and in serum. At the same time, we evaluated the relationships between hepcidin, fpn, and anemia.ResultsMean serum hepcidin was 8.18 ± 3.75 μg/L in bca patients with anemia and 4.53 ± 2.07μg/L in those without anemia, a statistically significant difference (t = 3.7090, p < 0.01). Mean serum fpn was obviously lower in the anemia group than in the non-anemia group (1.77 ± 0.51 μg/L vs. 2.46 ± 0.52 μg/L, t = 3.5115, p < 0.01). Serum hepcidin and hemoglobin were negatively correlated (r = −0.502, p < 0.01); however, serum fpn was positively correlated with hemoglobin, and serum hepcidin was negatively correlated with fpn. The rates of hepcidin and fpn expression in bca tissues were 50.0% and 61.2% respectively, but no association with anemia was observed. We also observed no relationship between expression of hepcidin and fpn in serum and in tissue.ConclusionsIn bca patients, expression of hepcidin in serum was high, but expression of fpn was low, suggesting that serum hepcidin plays a major role in anemia in those patients. Expression of hepcidin and fpn in bca tissue showed no correlation with their expression in serum and no clear relationship with anemia.     

Determinants of hepcidin levels in sepsis-associated acute kidney injury: Impact on pAKT/PTEN pathways?

The antimicrobial β-defensin-like role of hepcidin (HEPC) has been increasingly investigated for its potential role in acute kidney injury (AKI). In sepsis-induced AKI, there is a complex interplay between positive and negative regulation of HEPC, with consequently altered distributions of iron caused by changes in HEPC levels. The aim of the current research was to assess serum HEPC levels in a cohort of septic patients with AKI and investigate the regulatory impact of hypoxia-inducing factor (HIF)-1α, erythropoietin (EPO) and inflammation on HEPC levels and related signal cascades in these patients. Baseline, higher levels of SCr (2.3-fold), blood urea nitrogen (BUN) (1.8-fold), uric acid (2.3-fold) and white blood cell (2.3-fold) were noted in septic AKI patients, along with decreased levels of albumin (15.7%), creatinine (44.7%) and BUN/creatinine ratios (23.8%), compared to in normal subjects. These hosts also had increased serum levels of TNFα (4.4-times) and TGFβ1 (3.2-times) compared to controls (p?相似文献