Products of lipopolysaccharide-activated macrophages (tumor necrosis factor-alpha, transforming growth factor-beta) but not lipopolysaccharide modify DNA synthesis by rat trophoblast cells exhibiting the 80-kDa lipopolysaccharide-binding protein.

Abstract

Pregnancy losses from gram negative bacterial infections could be caused by direct effects of LPS on placental cells, or indirectly via LPS activation of macrophages in the uteroplacental unit. To evaluate those alternatives, LPS, LPS-activated peritoneal cells, conditioned medium from LPS-activated peritoneal cells, and some purified and recombinant molecules known to be secreted by activated macrophages were tested for their abilities to modify DNA synthesis by rat trophoblast cells. Three trophoblast cell lines derived from midgestation placentas of outbred and inbred rats were used for the experiments. Although the 80-kDa LPS-binding protein was demonstrated on trophoblast cells, LPS alone had no effect on the ability of trophoblast cells to synthesize DNA. In cocultures, trophoblast cell DNA synthesis was slightly enhanced by low concentrations of both unstimulated and LPS-activated peritoneal cells. At higher concentrations, LPS-activated cells caused significant inhibition of DNA synthesis by trophoblast cells. Conditioned media from LPS-activated peritoneal cells were highly inhibitory to trophoblast cell DNA synthesis. When specific molecules likely to be components of those media were tested, IL-1 was found to have a modest but reproducible stimulatory effect and PGE2 did not change trophoblast cell incorporation of [3H]TdR. In contrast, trophoblast cell DNA synthesis was markedly inhibited in a dose-dependent manner by both TNF-alpha and TGF-beta 1. No differences in the sensitivity of trophoblast cells from outbred and inbred rats were observed. Given the limitations of the experimental model system, the results suggest that in cases of infection by gram-negative bacteria LPS may have an adverse effect on pregnancy by stimulating resident macrophages to generate and release molecules that are inhibitory to trophoblast cell DNA synthesis.

Pentoxifylline as a therapeutic option for pre‐eclampsia: a study on its placental effects

“…The anti‐inflammatory properties of pentoxifylline are of particular interest in pre‐eclamptic patients, whom display increased plasma levels of pro‐inflammatory cytokines, including IL‐6 , IFN‐γ and TNF‐α (Jonsson et al, 2006 ; Szarka et al, 2010 ), and suppressed production of IL‐5 and the anti‐inflammatory cytokine IL−10 (Azizieh et al, 2005 ; Szarka et al, 2010 ). This inflammatory response may originate from the pre‐eclamptic placenta (Munno et al, 1999 ) and could subsequently contribute to placental dysfunction, endothelial damage and ischaemic‐reperfusion injury (Hunt et al, 1989 ; Nawroth & Stern, 1986 ; Raghupathy & Raghupathy, 2013 ; Stark, 1993 ). Speer et al ( 2017 ) observed that pentoxifylline reduced LPS‐induced inflammation in an ex vivo placental explant model, often used to study pre‐eclampsia.…”