Toll-like receptor 2/4 inhibitors can reduce preterm birth in mice.

Objectives: Preterm birth (PTB) occurs in 5% to 18% of newborns. However, the underlying inflammatory mechanisms have not been elucidated.

Methods: We established a mouse model of infection-associated PTB. Physical signs in pregnant mice with or without lipopolysaccharide (LPS) treatment were observed, and the frequencies of Toll-like receptor (TLR)2- and TLR4-positive CD11b+ cells were analyzed. Cytokine levels in plasma and pathological changes were assessed following LPS treatment. A rescue experiment was used to probe potential immunologic mechanisms underlying PTB.

Results: Lymphocyte infiltration could be observed in the placentas of mice following intrauterine injection with LPS. The percentage of inflammatory cells decreased 12 hours after treatment. Moreover, TLR2 and TLR4 expression in peripheral blood cells was significantly increased 4 hours after intraperitoneal injection of LPS. Peak TLR2 and TLR4 expression in peripheral blood cells occurred 8 hours post-treatment. TLR4 and TLR-2/4 inhibitors reduced levels of interleukin-10, interferon-γ, and tumor necrosis factor-α in peripheral blood and delayed PTB.

Conclusions: TLR2 and TLR4 inhibition could play important roles in PTB.