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Immunofluorescence to Monitor the Cellular Uptake of Human Lactoferrin and its Associated Antiviral Activity Against the Hepatitis C Virus
Published on: October 1, 2015
The immunosuppressive mini-domain of human lactoferrin
I Z Siemion1, J Sloń, Z Wieczorek
1Institute of Chemistry, University of Wroclaw, Poland.
Insights
Lactoferrin (LF) contains both immune-stimulating and immune-suppressing regions. A specific peptide loop in LF
Area of Science:
- Immunology
- Biochemistry
- Peptide Science
Background:
- Lactoferrin (LF) is a multifunctional protein with known immune-modulating properties.
- Previous research identified immunostimulating domains within LF.
- The immunomodulatory roles of specific LF peptide sequences require further elucidation.
Purpose of the Study:
- To investigate the immunosuppressive activity within the lactoferrin (LF) N-lobe.
- To characterize the immunomodulatory effects of different LF peptide fragments.
- To compare the activities of LF N-lobe and C-lobe related peptides.
Main Methods:
- Peptide synthesis and characterization.
- In vitro assays for immunosuppressive activity.
- In vivo testing of humoral and cellular immune responses (DTH test).
Main Results:
- A pentadecapeptide loop (231-245) in the LF N-lobe exhibits immunosuppressive activity, mediated by a thymopentin-like sequence.
- Peptides from the LF C-lobe (575-589 loop) show different immunomodulatory activity compared to N-lobe peptides.
- LF fragments 27-34 and 309-315 stimulate the humoral immune response in vivo, with fragment 27-34 linked to a known immunostimulative region.
Conclusions:
- The lactoferrin (LF) molecule possesses both previously identified immunostimulating domains and a novel immunosuppressive region.
- Specific amino acid differences, such as Asp vs. Thr, significantly influence the immunomodulatory activity of LF peptide loops.
- LF fragments can differentially impact cellular and humoral immune responses.
Abstract:
It has been found that the disulphide-bridged 231-245 pentadecapeptide loop of the lactoferrin (LF) N-lobe contains a region of immunosuppressive activity. The activity resides within a thymopentin-like sequence (Arg-Lys-Pro-Val-Asp) of the loop. Peptides related to the 575-589 loop of the LF C-lobe differ in their immunomodulatory activity from those related to the 231-245 loop. We ascribe this difference to the replacement of the Asp residue in the 231-245 loop by Thr in the 575-589 loop. Two other fragments of LF which were studied, 27-34 and 309-315, do not manifest any activity in the DTH test (cellular immune response), but, on testing in vivo, stimulate the humoral immune response. The 27-34 fragment is related to the bactericidal and immunostimulative region of LF identified by Bellamy et al. [1]. Our results show that the LF molecule contains, not only the known immunostimulating mini-domain, but also a region endowed with immunosuppressive activity.
