title: PIF direct immune regulation: Blocks mitogen-activated PBMCs proliferation, promotes TH2/TH1 bias, independent of Ca(2+).
abstract: PreImplantation Factor (PIF(9&15)) secreted by viable embryos exerts an essential transplant acceptance and immune regulatory role in pregnancy. Synthetic PIF replicates endogenous PIF's effect in pregnant and non-pregnant immune disorder models. PIF binds macrophages to regulate CD3/CD28-induced T-cell response. We present evidence that PIF regulates the co-stimulatory T-cell receptor, CD2, which binds to and is activated by phytohemagglutinin (PHA), a potent mitogen, confirming PIF's ability to systemically respond to diverse immune stimulants. PIF's effect on PHA-activated PBMC (male and non-pregnant females) proliferation and cytokine secretion was tested, showing that both PIF(9&15) block PHA-induced PBMC proliferation and promote anti-inflammatory IL10 secretion, while reducing pro-inflammatory IFNγ secretion. Thus favoring a T(H)2 cytokine bias. Surface plasmon resonance spectroscopy, immunocytochemistry and Flex station experiments reveal that PIF effect is direct. PIF targets intracellular targets but does not affect early Ca(2+) mobilization. By promoting the CD2 receptor in activated T-cells and through inhibition of co-ligand CD58 expression, PIF regulates antigen-presenting cell (APC)-T-cell interactions required for PHA action. Structure-based design demonstrated that PIF15 offers improved target specificity as compared to PIF9. Collectively, PIF directly regulates mitogen-induced PBMC activation. Results support PIF translation for therapy of immune disorders.
authors.affiliation: The Society for the Investigation of Early Pregnancy (SIEP), Cherry Hill, NJ, USA; BioIncept LLC, Cherry Hill, NJ, USA. Electronic address: barnea@earlypregnancy.org.
authors.forename: Eytan R
authors.initials: ER
authors.lastname: Barnea
authors.affiliation: PharmMedInfo, Poulsbo, WA, USA. Electronic address: david.kirk1@comcast.net.
authors.forename: David
authors.initials: D
authors.lastname: Kirk
authors.affiliation: Bulgarian Academy of Science, Sofia, Bulgaria. Electronic address: krasiot@abv.bg.
authors.forename: Krassimira
authors.initials: K
authors.lastname: Todorova
authors.affiliation: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK. Electronic address: jmcelh@essex.ac.uk.
authors.forename: James
authors.initials: J
authors.lastname: McElhinney
authors.affiliation: Bulgarian Academy of Science, Sofia, Bulgaria. Electronic address: soren.hayrabedyan@gmail.com.
authors.forename: Soren
authors.initials: S
authors.lastname: Hayrabedyan
authors.affiliation: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK. Electronic address: nelson@essex.ac.uk.
authors.forename: Nelson
authors.initials: N
authors.lastname: Fernández
mesh_terms: D000938:Antigen-Presenting Cells / Q000276:immunology; D018801:CD2 Antigens / Q000378:metabolism; D018106:CD28 Antigens / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D018968:CD58 Antigens / Q000096:biosynthesis; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D016753:Interleukin-10 / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D008297:Male; D056004:Molecular Dynamics Simulation; D010455:Peptides / Q000494:pharmacology*; D010835:Phytohemagglutinins / Q000378:metabolism*; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000276:immunology*; D020349:Surface Plasmon Resonance; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology
chemical_list: D018801:CD2 Antigens; D018106:CD28 Antigens; D017252:CD3 Complex; D018968:CD58 Antigens; D015220:Calcium Channels; C508609:IL10 protein, human; D010455:Peptides; D010835:Phytohemagglutinins; D011257:Pregnancy Proteins; C000605122:preimplantation factor, human; D016753:Interleukin-10; C569738:preimplantation factor, synthetic; D007371:Interferon-gamma; D002118:Calcium
keywords: Direct effect; Embryo tolerance; PreImplantation Factor (PIF); Systemic immune regulation