Effects of lipopolysaccharide on interleukin-6 production in perfused human placental cotyledons

The Effects of Magnesium Sulfate on the Inflammatory Response of Placentas Perfused With Lipopolysaccharide: Using the Ex Vivo Dual-Perfused Human Single-Cotyledon Model

OBJECTIVES

Multiple mechanisms have been proposed for the neuroprotective effects of magnesium sulfate (MgSO₄). We aimed to examine the effects of lipopolysaccharide (LPS) and MgSO₄ on the placental expression of nuclear factor κ light chain enhancer of activated B cells (NF-κB), interleukin (IL) 6, adrenocorticotropic hormone (ACTH), and nitric oxide synthase (NOS); all known to participate in the inflammatory cascade.

METHODS

Placentas were obtained and selected cotyledons cannulated and dually perfused ex vivo. Placentas were perfused with 4 perfusion protocols: culture medium (M-199; controls), LPS (1 μg/mL), MgSO₄ (6 g/dL), and LPS + MgSO₄. Each perfusion experiment continued for 3 hours. Sixteen perfusion experiments were analyzed, 4 separate placentas were studied for each protocol. The protein levels in the perfused cotyledons were studied by Western blot analysis and compared between the groups. Interleukin 6 levels were studied in the maternal and fetal perfusate.

RESULTS

The expression of NF-κB p65, IL-6, ACTH, and NOS proteins levels were significantly increased in placentas perfused with LPS as compared to placentas perfused with M-199, MgSO₄ ( P < .01 for all). Placentas perfused with LPS+ MgSO₄ had similar proteins levels as in the controls and MgSO₄ groups. Lipopolysaccharide significantly increased IL-6 levels in maternal perfusate.

CONCLUSIONS

In the human placenta, MgSO₄ blocks the increase in the proteins levels of NF-κB, IL-6, ACTH, and NOS in response to inflammatory stimuli. Magnesium sulfate attenuates excessive placental inflammatory response. The decrease in placental ACTH levels following perfusion with MgSO₄ may point to an additional non-anti-inflammatory mechanism of MgSO₄.

Toll-like receptor 4-mediated immune stress in pregnant rats activates STAT3 in the fetal brain: role of interleukin-6

BACKGROUND

Prenatal exposure to pathogens induces long lasting effect on brain function and plasticity. It is unclear how maternal immune stress impacts fetal brain development. Immune challenged pregnant rats induce the production of inflammatory cytokines including tumor necrosis factor (TNF)α, interleukin (IL)1β, and IL-6. IL-6 crosses the placenta but its mechanism of action on fetal brain is unclear.

METHODS

Gestation day 15 (GD15) rats were given a single injection of lipopolysaccharide (LPS) (100 µg/kg) in the presence or the absence of an IL-6 neutralizing antibody (IL-6Ab, 10 µg/kg). The activation of the intracellular signal of IL-6; signal transducer and activator of transcription (STAT3) and levels of glucocorticoids (GCs) were monitored in fetal brains.

RESULTS

LPS administration to GD15 rats significantly increased the phosphorylation levels of STAT3 in fetal brains. Such activation was blunted by IL-6Ab. LPS induced a significant rise in GCs in the plasma of dams but not in fetal brains. IL-6Ab significantly reduced LPS-induced GCs in maternal plasma.

CONCLUSION

Toll-like receptor 4 (TLR4)-induced activation of the maternal innate immune system affects fetal brains likely via the mobilization of IL-6/STAT3 pathway. In contrast, TLR4-stimulated maternal GCs release is less likely to play a significant role in fetal brain development.