Pentoxifylline attenuates HPV-16 associated necrosis in placental trophoblasts

Human papillomaviruses (HPV) have been associated with placental inflammation resulting in high-risk preterm birth. The premise for this study was that treatment with anti-inflammatory pentoxifylline would inhibit HPV-mediated placental cell death. The objectives were: (1) to study the effects of HPV-16 exposure on trophoblast cells and (2) to evaluate pentoxifylline in preventing the damaging effects of HPV-16.

Mouse embryos (1-cell) were cultured (G1plus medium, 72 h, 37 °C, 5 % CO2 in air), divided into four groups at blastocyst-stage and incubated to implantation stage. Implanted trophoblasts were exposed to either HPV-16 (group 1), concomitant HPV-16 and 3 mM pentoxifylline (group 2), 3 mM pentoxifylline only (group 3) or control medium (group 4) and further incubated for 24 h. HPV-16 were from SiHa cell lysates. Trophoblast structural integrity was assessed by morphometric analysis while apoptosis and necrosis were detected using dual-stain fluorescence assay.

Trophoblast outgrowth was reduced by 90% (P < 0.05) in HPV-16 presence (629 ± 265 µ(2), mean + SEM) when compared with controls (6,456 ± 795 µ(2)). Pentoxifylline attenuated the effects of HPV-16 (4,308 ± 362 µ(2)). Nuclear size of HPV-16 infected trophoblasts was smallest among the groups (P < 0.005). HPV-16 decreased cell viability and increased necrosis but not apoptosis. Pentoxifylline prevented HPV-16 associated necrosis in trophoblasts.

HPV-16 decreased nuclear size and trophoblast outgrowth but these effects were attenuated by the phosphodiesterase inhibitor, pentoxifylline. The action of HPV-16 on trophoblasts was increased cell necrosis suggesting that HPV-16 pathogenesis involved either cAMP inhibition and/or activated TNF pathways.