Expression, characterization, and biologic activity of recombinant human lactoferrin in rice.
BACKGROUND
Lactoferrin has been suggested to have many biologic activities, such as facilitating iron absorption and having antimicrobial and antiinflammatory effects. In humans, several of these activities are likely to only be facilitated by human lactoferrin because they depend on the binding of human lactoferrin to specific receptors. Rice may be a useful vehicle to introduce recombinant human lactoferrin to infant foods because it has low allergenicity and is likely to be safer than using microorganisms or transgenic animals.


METHODS
Recombinant human lactoferrin was expressed in the rice cell culture system, and its biologic activity was assessed by iron-binding and -releasing properties, antimicrobial activity, and binding and uptake to Caco-2 cells. The authors also compared the stability of recombinant and native human lactoferrins against heat, low pH, and in vitro digestion.


RESULTS
Biologic activity of rice-expressed recombinant human lactoferrin was similar to that of native human lactoferrin. Heat-treated proteins retained their functional activities except with severe treatment at 100 degrees C for 8 seconds, which disturbed the iron-binding capacity of recombinant human lactoferrin. Both types of proteins retained their functional activities between pH 2 and 7.4. After in vitro digestion, 50% of both proteins were detectable by enzyme linked immunosorbent assay. The remaining native and recombinant lactoferrins retained antimicrobial and Caco-2 binding and uptake activities.


CONCLUSIONS
The results indicate recombinant human lactoferrin has stability similar to native human lactoferrin when exposed to thermal treatment, pH treatment, and in vitro digestion, suggesting it may be active when added to infant formula.
Suzuki
Yasushi A
YA
Department of Nutrition, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA.
Kelleher
Shannon L
SL
Yalda
Dorice
D
Wu
Liying
L
Huang
Jianmin
J
Huang
Ning
N
Lönnerdal
Bo
B
D000595:Amino Acid Sequence; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism; D018938:Caco-2 Cells; D002460:Cell Line; D004063:Digestion; D004797:Enzyme-Linked Immunosorbent Assay; D018506:Gene Expression Regulation, Plant; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007223:Infant; D007225:Infant Food; D007231:Infant, Newborn; D007501:Iron / Q000378:metabolism*; D007781:Lactoferrin / Q000235:genetics* / Q000494:pharmacology / Q000502:physiology*; D012275:Oryza / Q000737:chemistry / Q000235:genetics*; D030821:Plants, Genetically Modified; D011485:Protein Binding; D011994:Recombinant Proteins / Q000235:genetics / Q000494:pharmacology
D011994:Recombinant Proteins; D007501:Iron; D007781:Lactoferrin