Malaria-associated cytokine changes in the placenta of women with pre-term deliveries in Yaounde, Cameroon

The prevalence of pre-term deliveries (PTDs) is increased in women who become infected with Plasmodium falciparum during pregnancy. Because prematurity is a risk factor for newborns, it is important to identify conditions that contribute to malaria-associated PTDs. Plasmodium falciparum-infected erythrocytes sequester in the placenta and attract activated mononuclear cells that secrete pro-inflammatory cytokines. Increased inflammatory cytokine levels in other microbial infections are associated with PTDs. To determine if such is the case in women with placental malaria, concentrations of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-4 (IL-4), and IL-10 were measured in placental plasma of 391 malaria-infected and -uninfected Cameroonian women with premature and full-term deliveries. Risk factors for malaria-associated PTDs included peripheral and placental parasitemias greater than 1%, maternal anemia, elevated IL-10 levels, and low TNF-α:IL-10 ratios due to over-expression of IL-10. Alterations in cytokine levels may contribute to PTDs through the induction of anemia and/or altering cellular immune responses required for eliminating placental parasites.