Transmission in utero is an important source of pediatric HIV infections, and miscarriages occur at an elevated rate in HIV-infected women. The mechanism for transplacental transmission or perturbation of pregnancy by the virus is unknown. Placental immunomodulators are involved in the regulation of normal pregnancy. Successful pregnancy typically is biased toward a Th2-mediated immune response, and Th1 cytokine expression must by suppressed. Trophoblastic cells and decidual leukocytes express immunomodulators that regulate placental immunology. Trophoblasts can be infected with HIV. HIV expression is augmented by some immunomodulators that are expressed in the placenta, and HIV infections can alter the profile of trophoblastic cytokines. Thus, dysregulation of placental immunology probably occurs during HIV infections, possibly contributing to HIV vertical transfer and fetal damage. The FIV-infected cat is a model for HIV vertical infections, with vertical infection resulting in compromised pregnancy. Preliminary data indicate increased expression of placental Th1 cytokines in FIV-infected queens. The purpose of this project is to evaluate placental immunopathology at the cellular level, at early and late gestation, to begin to understand mechanistically how lentiviral infection compromises pregnancy.
The specific aims of this project are to: 1) Determine whether FIV infection induces immunopathology in trophoblasts. The expression of representative Th1 and Th2 cytokines, the chemokine receptor CXCR4 (a coreceptor for FIV), its ligand SDF, and FIV in placental trophoblasts will be determined using laser capture microdissection (LCM) to capture trophoblasts, followed by TaqMan real time PCR to assess expression of the genes. 2) To determine whether FIV infection induces placental cytotoxicity. Decidual leukocyte populations will be quantified using immunohistochemistry, and cytokine profiles in these cells will be determined, following LCM and real time PCR. The effect of viral infection on apoptosis of trophoblasts will be examined using the TUNEL assay. 3) To evaluate whether immunological changes in the peripheral and uterine circulation of queens are predictive of compromised pregnancy. Flow cytometry will be done to quantify leukocyte populations; cytokine expression in these cells will be quantified by real time PCR; and Th1:Th2 cytokine ratios in serum will be measured. Collectively, the data obtained from this study may identify placental immunological factors that result in FIV transplacental transmission and compromised pregnancy and identify immunological evidence of pregnancy distress in the peripheral circulation. The long-term goal of this project is to provide the intellectual basis for immune-based intervention strategies to minimize virus-induced placental immunopathology and reproductive failure. ? ?
