Immunoassay for human serum hemojuvelin.
BACKGROUND
Hemojuvelin, a critical regulator of iron homeostasis, is involved in the regulation of hepcidin expression and iron homeostasis. It is expressed both as a membrane-bound form and as a soluble one. Serum hemojuvelin can be produced by secretion following furin cleavage or by proteolytic cleavage of the membrane-bound form by matriptase 2 (TMPRSS6). These forms contribute to down-regulation of hepcidin expression upon iron deficiency or hypoxia. This study describes the development and validation of the first enzyme-linked immunosorbent assay for hemojuvelin in human serum.


METHODS
This assay is based on the use of a recombinant human repulsive guidance molecule-c peptide and a polyclonal antibody against hemojuvelin able to recognize the recombinant peptide and the native soluble hemojuvelin by immunoprecipitation.


RESULTS
The enzyme-linked immunosorbent assay was validated and appeared to be a robust method with intra- and inter-coefficients of variance ranging from 2.6% to 15%. The assay was able to quantify hemojuvelin levels in a control population within a range from 0.88 to 1.14 mg/L. Patients with iron-refractory iron-deficiency anemia with a mutation in the TMPRSS6 gene were found to have lower levels of circulating hemojuvelin than those in healthy patients. The enzyme-linked immunosorbent assay also showed that soluble hemojuvelin levels were significantly higher in patients with anemia of chronic disease than in control individuals.


CONCLUSIONS
This enzyme-linked immunosorbent assay has a good specificity and sensitivity for the quantification of soluble hemojuvelin in human serum and could be a valuable aid to understanding the physiological role of this protein.
Brasse-Lagnel
Carole
C
Laboratoire de Biochimie Médicale, Hôpital Universitaire de Rouen, EA4309 Endothélium Microvasculaire et Lésions Cérébrales Néonatales, Université de Rouen, Rouen, France. carole.lagnel@univ-rouen.fr
Poli
Maura
M
Lesueur
Céline
C
Grandchamp
Bernard
B
Lavoinne
Alain
A
Beaumont
Carole
C
Bekri
Soumeya
S
D000293:Adolescent; D000328:Adult; D000740:Anemia / Q000097:blood; D018798:Anemia, Iron-Deficiency / Q000097:blood* / Q000188:drug therapy / Q000235:genetics; D015153:Blotting, Western; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D058851:GPI-Linked Proteins / Q000097:blood*; D000071020:Hemochromatosis Protein; D006801:Humans; D007501:Iron / Q000378:metabolism / Q000627:therapeutic use; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D015203:Reproducibility of Results; D012697:Serine Endopeptidases / Q000235:genetics
D058851:GPI-Linked Proteins; C481006:HJV protein, human; D000071020:Hemochromatosis Protein; D008565:Membrane Proteins; D007501:Iron; D012697:Serine Endopeptidases; C504318:TMPRSS6 protein, human