During pregnancy, the endometrium of the ewe secretes large amounts of a progesterone-induced protein of the serpin superfamily of serine proteinase inhibitors called ovine uterine serpin (OvUS). This protein inhibits lymphocyte proliferation in response to concanavalin A (ConA), phytohemagglutinin (PHA), or mixed lymphocyte reaction. The purpose of these experiments was to characterize the mechanism by which OvUS inhibits lymphocyte proliferation. Ovine US caused dose-dependent inhibition of lymphocyte proliferation induced by phorbol myristol acetate (PMA), an activator of protein kinase C. The PHA-induced increase in CD25 expression was inhibited in peripheral blood mononuclear leukocytes (PBML) by OvUS. However, no effect of OvUS on Con A-induced expression of CD25 was observed. Further analysis using two-color flow cytometry revealed that OvUS inhibited ConA-induced expression of CD25 in γδ-TCR– cells but not γδ-TCR+ cells. Stimulation of PBML for 14 hr with ConA resulted in an increase in steady state amounts of interleukin-2 (IL-2) mRNA that was not inhibited by OvUS. Ovine US was also inhibitory to lymphocyte proliferation induced by human IL-2. Results suggest that OvUS acts to inhibit lymphocyte proliferation by blocking the upregulation of the IL-2 receptor and inhibiting IL-2–mediated events. Lack of an effect of OvUS on ConA-stimulated CD25 expression in γδ-TCR+ cells may reflect a different mechanism of activation of these cells or insensitivity to inhibition by OvUS.
Get full access to this article
View all access options for this article.
References
1.
IngNH, RobertsRM. The major progesterone-modulated proteins secreted into the sheep uterus are members of the serpin superfamily of serine protease inhibitors. J Biol Chem264: 3372–3379, 1989.
2.
MoffattJ, BazerFW, HansenPJ, ChunPW, RobertsRM. Purification, secretion, and immunocytochemical localization of the uterine milk proteins, major progesterone-induced proteins in uterine secretions of the sheep. Biol Reprod36: 419–430, 1987.
3.
IngNH, FrancisH, McDonnellJJ, AmannJF, RobertsRM. Progesterone induction of the uterine milk proteins: Major secretory proteins of sheep endometrium. Biol Reprod41: 643–654, 1989.
4.
LeslieMV, HansenPJ. Progesterone-regulated secretion of the serpin-like proteins of the ovine and bovine uterus. Steroids56: 589–597, 1991.
5.
MalathyPV, ImakawaK, SimmenRC, RobertsRM. Molecular cloning of the uteroferrin-associated protein, a major progesterone-induced serpin secreted by the porcine uterus, and the expression of its mRNA during pregnancy. Mol Endocrinol4: 428–440, 1990.
6.
MathialaganN, HansenTR. Pepsin-inhibitory activity of the uterine serpins. Proc Natl Acad Sci U S A93: 13653–13658, 1996.
7.
LeslieMV, HansenPJ, NewtonGR. Uterine secretions of the cow contain proteins that are immunochemically related to the major progesterone-induced proteins of the sheep uterus. Dornest Anim Endocrinol7: 517–526, 1990.
8.
TravisJ, GuzdekA, PotempaJ, WatorekW.Serpins: Structure and mechanism of action. Biol Chem Hoppe Seyler371(Suppl):3–11, 1990.
9.
StoneSR, Le BonniecBF. Inhibitory mechanism of serpins: Identification of steps involving the active-site serine residue of the protease. J Mol Biol265: 344–362, 1997.
10.
PeltierMR, HansenPJ. Further evidence that biological activity of the ovine uterine serpin does not reside in the C-terminal region containing the putative reactive center loop, (abstract)Biol Reprod58(Suppl 1):129, 1998.
11.
SegersonEC, MoffattRJ, BazerFW, RobertsRM. Suppression of phytohemagglutinin-stimulated lymphocyte histogenesis by ovine uterine milk protein. Biol Reprod30: 1175–1186, 1984.
12.
SkopetsB, HansenPJ. Identification of the predominant proteins in uterine fluids of unilaterally pregnant ewes that inhibit lymphocyte proliferation. Biol Reprod49: 997–1007, 1993.
13.
GottshallSL, HansenPJ. Enhancement of mitogen-induced lymphocyte proliferation in sheep. Zcntralbl Veterinarmed B41: 541–547, 1994.
14.
SkopetsB, LiuWJ, HansenPJ. Effects of endometrial serpin-like proteins on immune responses in sheep. Am J Reprod Immunol33: 86–93, 1995.
15.
LiuWJ, HansenPJ. Effect of the progesterone-induced serpin-like proteins of the sheep endometrium on natural-killer-cell activity in sheep and mice. Biol Reprod49: 1008–1014, 1993.
16.
HansenPJ, BazerFW, SegersonECJr.Skin graft survival in the uterine lumen of ewes treated with progesterone. Am J Reprod Immunol Microbiol12: 48–54, 1986.
17.
GottshallSL, HansenPJ. Regulation of leucocyte subpopulations in the sheep endometrium by progesterone. Immunology76: 636–641, 1992.
18.
LiuW-J, PeltierMR, HansenPJ. Binding of the ovine uterine serpin to lymphocytes. Am J Reprod Immunol41: 428–432, 1999.
19.
EmondV, FortierMA, MurphyBD, LambertRD. Prostaglandin E2 regulates both interleukin-2 and granulocyte-macrophage colony-stimulating factor gene expression in bovine lymphocytes. Biol Reprod58: 143–151, 1998.
20.
SmithPK, KrohnRI, HermansonGT, MalliaAK, GartnerFH, ProvenzanoMD, FujimotoEK, GoekeNM, OlsonBJ, KlenkDC. Measurement of protein using bicinchoninic acid. Anal Biochem150: 76–83, 1985.
LowBG, HansenPJ. Actions of steroids and prostaglandins secreted by the placenta and uterus of the cow and ewe on lymphocyte proliferation in vitro. Am J Reprod Immunol Microbiol18:71–75, 1988.
23.
SAS/STAT.User's Guide (6th ed). Cary, NC: Statistical Analysis System Institute, Inc., 1990.
24.
ConoverWJ, ImanRL. Rank transformations as a bridge between parametric and nonparametric statistics. Am Stat35: 124–129, 1981.
25.
SzamelM, EbelU, UciechowskiP, KaeverV, ReschK.T-cell antigen receptor-dependent signaling in human lymphocytes: Cholera toxin inhibits interleukin-2 receptor expression but not interleukin-2 synthesis by preventing activation of a protein kinase C isotype, PKC-α. Biochim Biophys Acta1356: 237–248, 1997.
26.
SzamelM, LeufgenH, KurrleR, ReschK.Differential signal transduction pathways regulating interleukin-2 synthesis and interleukin-2 receptor expression in stimulated human lymphocytes. Biochim Biophys Acta1235: 33–42, 1995.
27.
SzamelM, AppelA, SchwinzerR, ReschK.Different protein kinase C isoenzymes regulate IL-2 receptor expression or IL-2 synthesis in human lymphocytes stimulated via the TCR. J Immunol160: 2207–2214, 1998.
28.
AggarwalS, LeeS, MathurA, GollapudiS, GuptaS.12-Deoxyphorbol-13-O-phenylacetate 20 acetate [an agonist of protein kinase C β1 (PKC β1)] induces DNA synthesis, interleukin-2 (IL-2) production, IL-2 receptor α-chain (CD25) and β-chain (CD 122) expression, and translocation of PKC β isozyme in human peripheral blood lymphocytes: Evidence for a role of PKC β1 in human T-cell activation. J Clin Immunol14: 248–256, 1994.
29.
GomezJ, PittonC, GarciaA, Martinez de AragonA, SilvaA, RebolloA.The ζ isoform of protein kinase C controls interleukin-2-mediated proliferation in a murine T-cell line: Evidence for an additional role of protein kinase C ε and β. Exp Cell Res218: 105–113, 1995.
30.
MeeusenE, FoxA, BrandonM, LeeCS. Activation of uterine intraepithelial γδ T-cell receptor-positive lymphocytes during pregnancy. Eur J Immunol23: 1112–1117, 1993.
31.
BujdosoR, LundBT, EvansCW, McConnellI.Different rates of interleukin-2 receptor expression by ovine γδ and αβ T cells. Vet Immunol Immunopathol39: 109–114, 1993.
32.
EvansCW, LundBT, McConnellI, BujdosoR.Antigen recognition and activation of ovine γδ T cells. Immunology82: 229–237, 1994.
33.
VerhagenAM, BrandonMR, NashAD. Characterization of the ovine interleukin-2 receptor: Differential induction on precultured αβ and γδ T cells. Immunology79: 471–478, 1993.
