title: Effect of iron saturation level of lactoferrin on osteogenic activity in vitro and in vivo.
abstract: We studied the effect of iron saturation level on the osteogenic activity of lactoferrin (LF) in vitro and in vivo. Different iron saturation levels of LF (1.0, 9.0, 38, 58, and 96%) were prepared as the following samples: apo-LF, LF-9, LF-38, LF-58, and holo-LF. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, we observed that the stimulating osteoblast proliferation activity of LF in vitro decreased with increasing iron saturation level at 100 and 1,000 μg/mL. In vivo, 4-wk-old ICR Swiss male mice were randomly divided into 4 groups: blank control (physiological saline), negative control (BSA), apo-LF, and holo-LF. Four groups of mice were injected subcutaneously with physiological saline, BSA, apo-LF, or holo-LF over the calvarial surface twice a day for 5 consecutive days at a dose of 4 mg/kg per day. Bone histomorphometry showed that new bone formation (assessed using tetracycline-HCl labels) tended to be stronger with apo-LF than with holo-LF. Using fluorescence spectroscopy and circular dichroism measurements, we found that exposure of tryptophan increased, α-helix content increased, but β-structure content decreased with increasing iron saturation level. These findings indicated that the osteogenic activity of LF decreases with increasing iron saturation level in vitro and in vivo, which may be related to conformational changes in LF.
authors.affiliation: Key Laboratory of Functional Dairy, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
authors.forename: X Y
authors.initials: XY
authors.lastname: Wang
authors.forename: H Y
authors.initials: HY
authors.lastname: Guo
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.forename: P C
authors.initials: PC
authors.lastname: Wen
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.forename: Z R
authors.initials: ZR
authors.lastname: Guo
authors.forename: F Z
authors.initials: FZ
authors.lastname: Ren
mesh_terms: D000818:Animals; D002942:Circular Dichroism; D066298:In Vitro Techniques; D007501:Iron / Q000737:chemistry / Q000494:pharmacology*; D007781:Lactoferrin / Q000737:chemistry / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010012:Osteogenesis / Q000187:drug effects*; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence
chemical_list: D007501:Iron; D007781:Lactoferrin