Location: Warmwater Aquaculture Research UnitTitle: Immunomodulator expression in trophoblasts from the feline immunodeficiency virus FIV infected cat) Author
Submitted to: Journal of Virology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/5/2012
Publication Date: 7/5/2012
Citation: Scott, V.L., Shack, L.A., Eells, J.B., Ryan, P.L., Donaldson, J.R., Coats, K.S. 2012. Immunomodulator expression in trophoblasts from the feline immunodeficiency virus (FIV)- infected cat. Journal of Virology. 8:336. Interpretive Summary: Experimental feline immunodeficiency virus (FIV) infection of cats frequently causes pregnancy failure and is accompanied by inflammation in placental tissues. Cytokines, proteins which regulate immune function, are abnormally produced in these infected tissues. Trophoblasts, fetal-derived cells that form the placental chorionic villi, produce numerous cytokines and other immunoregulatory proteins that play a role in placental development and successful pregnancy. We hypothesized that FIV infection may cause abnormal expression of immunoregulatory proteins produced in trophoblasts, resulting in placental inflammation and pregnancy failure. The purpose of this project was to evaluate the production of representative cytokines and immunoregulators that promote or inhibit inflammation, along with FIV in trophoblasts. Trophoblasts were specifically identified in placental tissues collected from FIV-infected and uninfected cats at two stages of pregnancy (early and late-term). The trophoblasts were removed from the surrounding tissues using a procedure called laser capture microdissection (LCM), and the RNA was purified from the trophoblasts. The trophoblast RNA was used in a polymerase chain reaction procedure to measure levels of the immunoregulatory proteins and the virus. We detected both pro- and anti-inflammatory cytokines in trophoblasts and noted the levels of these cytokines increased from early to late pregnancy in normal tissues. Pregnancy loss was associated with decreased expression of immunoregulatory proteins which normally regulate the invasion of the trophoblasts into the uterine wall in other species, a requisite feature of placental development. The detection of FIV in trophoblasts was rare, suggesting that the high rate of reproductive failure in FIV-infected queens was not a direct result of viral replication in trophoblasts. The influence of placental immune cells on trophoblast function and pregnancy maintenance in the FIV-infected cat requires additional study.
Technical Abstract: FIV infection frequently compromises pregnancy under experimental conditions and is accompanied by aberrant expression of some placental cytokines. Trophoblasts produce numerous immunomodulators that play a role in placental development and pregnancy maintenance. We hypothesized that FIV infection may cause dysregulation of trophoblast immunomodulator expression, and aberrant expression of these molecules may potentiate inflammation and compromise pregnancy. The purpose of this project was to evaluate the expression of representative pro- (TNF-a, IFN-', IL-1', IL-2, IL-6, IL-12p35, IL-12p40, IL-18, and GM-CSF) and anti-inflammatory cytokines (IL-4, IL-5, and IL-10); CD134, a secondary co-stimulatory molecule expressed on activated T cells (FIV primary receptor); the chemokine receptor CXCR4 (FIV co-receptor); SDF-1a, the chemokine ligand to CXCR4; and FIV gag in trophoblasts from early- and late-term pregnancy. Methods: We used an anti-cytokeratin antibody in immunohistochemistry to identify trophoblasts selectively, collected these cells using laser capture microdissection, and extracted total RNA from the captured cell populations. Real time, reverse transcription-PCR was used to quantify gene expression.We detected IL-4, IL-5, IL-6, IL-1ß, IL-12p35, IL-12p40, and CXCR4 in trophoblasts from early- and late-term pregnancy. Expression of cytokines increased from early to late pregnancy in normal tissues. A clear, pro-inflammatory microenvironment was not evident in trophoblasts from FIV-infected queens at either stage of pregnancy. Reproductive failure was accompanied by down-regulation of both pro- and anti-inflammatory cytokines. CD134 was not detected in trophoblasts, and FIV gag was detected in only one of ten trophoblast specimens collected from FIV-infected queens. Feline trophoblasts express an array of pro- and anti-inflammatory immunomodulators whose expression increases from early to late pregnancy in normal tissues. Non-viable pregnancies were associated with decreased expression of immunomodulators which regulate trophoblast invasion in other species. The detection of FIV RNA in trophoblasts was rare, suggesting that the high rate of reproductive failure in FIV-infected queens was not a direct result of viral replication in trophoblasts. The influence of placental immune cells on trophoblast function and pregnancy maintenance in the FIV-infected cat requires additional study.