Hepcidin-20 (human)

Hepcidin 25 (hep-25) is a peptide primarily produced by human liver with a central role in iron homeostasis. Its isoform, hepcidin 20 (hep-20), has an unknown function and lacks the first five aminoacids of the amino-terminal portion. This sequence is crucial for iron regulation by hep-25 and contains a molecular motif able to bind metals. Aim of this study, was to evaluate the antibacterial properties of both peptides in vitro, against a wide range of bacterial clinical isolates and in different experimental conditions. Although both peptides were found to be bactericidal against a variety of clinical isolates with different antibiotic resistance profiles, hep-20 was active at lower concentrations than hep-25, in most of the cases. Killing kinetics, carried on in sodium-phosphate buffer at pH 7.4, demonstrated that bactericidal activity occurred not earlier than 30-90 min of incubation. Bactericidal activity of hep-25 was slightly enhanced in the presence of copper, while the same metal did not affect the activity of hep-20. Interestingly, bactericidal activity of both hepcidins was highly enhanced at acidic pH. Acidic pH (pH 5.0 and 6.6) not only reduced the microbicidal concentrations of hepcidins, but also shortened the killing times of both peptides, as compared to pH 7.4. Combining hep-20 and hep-25 at pH 5.0 a bactericidal effect could be obtained at very low concentrations of both peptides. These results render hepcidins interesting for the design of new drugs for the treatment of infections occurring in body districts with physiologic acidic pH.

Background/aim: Hepcidin is a cationic acute phase reactant synthesized by the liver. It has bactericidal properties and is a major regulator of iron homeostasis. Cationic antimicrobial peptides represent an innate antimicrobial defense system. We hypothesized that, like other cationic antimicrobial peptides, hepcidin is cytotoxic to cancer cells. Materials and methods: The cytotoxicity of human hepcidin against myeloma cells was assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and DNA fragmentation assays. Plasma membrane damage was quantified by propidium iodide (PI) staining. Cell membrane changes were visualized by scanning electron microscopy. Results: Hepcidin impaired myeloma cell survival and induced DNA fragmentation. PI staining and scanning electron microscopy revealed hepcidin-induced disruption of the plasma membrane. Conclusion: Human hepcidin is an anti-cancer peptide that induces myeloma cell lysis, and therefore may play a role in innate anticancer immunity. To our knowledge, this is the first biological function ascribed to human hepcidin that is not related to its antimicrobial and iron-regulatory properties.

Hepcidin, a key iron-regulator secreted from the liver, consists of 25 amino acids (hepcidin-25), blocks iron release from macrophages via internalization and degradation of cellular iron exporter ferroportin, and restrains the use of iron in organs. Hepcidin mRNA and protein are also expressed in the human heart. A short form of hepcidin that lacks 5 amino-acid residues in the N-terminus (hepcidin-20) has been found in human serum, although its physiological role is unknown. Here, we successfully measured the serum levels of hepcidin-25 and hepcidin-20 in 12 patients with acute myocardial infarction (AMI) using surface-enhanced laser desorption ionization time of flight mass spectrometry. Among the selected 10 patients, whose blood samples were taken within 4 hours after a heart attack, all the patients showed elevated serum levels of hepcidin-20 [between 31.7 and 285.1 arbitrary unit (AU); normal level < 9.3 AU], while 8 patients showed high levels of hepcidin-25 (9.3-271.4; normal < 25.5 AU). The hepcidin-20 level was decreased to nearly the normal level on day 7 (range of 2.9 to 12.5 AU) in the 12 patients, whereas the hepcidin-25 level remained high on day 7 in 8 patients. Furthermore, the elevated levels of hepcidin-25 and hepcidin-20 were not correlated with the serum levels of markers for inflammation, interleukin-6 and C-reactive protein, in the patients with AMI. In conclusion, the serum hepcidin-20 is transiently elevated in response to acute cardiac ischemia. Measurement of serum hepcidin-20, rather than hepcidin-25, is helpful for diagnosis of acute myocardial infarction.