Activation of the maternal immune system induces endocrine changes in

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Brain Behav Immun. 2010 Dec 30.

Activation of the maternal immune system induces endocrine changes in the

placenta via IL-6.

Hsiao EY, PH.

California Institute of Technology, Pasadena, CA 91125, USA.

Abstract

Activation of the maternal immune system in rodent models sets in motion a

cascade of molecular pathways that ultimately result in autism- and

schizophrenia-related behaviors in offspring. The finding that interleukin-6

(IL-6) is a crucial mediator of these effects led us to examine the mechanism by

which this cytokine influences fetal development in vivo. Here we focus on the

placenta as the site of direct interaction between mother and fetus and as a

principal modulator of fetal development. We find that maternal immune

activation (MIA) with a viral mimic, synthetic double-stranded RNA (poly(I:C)),

increases IL-6 mRNA as well as maternally-derived IL-6 protein in the placenta.

Placentas from MIA mothers exhibit increases in CD69+ decidual macrophages,

granulocytes and uterine NK cells, indicating elevated early immune activation.

Maternally-derived IL-6 mediates activation of the JAK/STAT3 pathway

specifically in the spongiotrophoblast layer of the placenta, which results in

expression of acute phase genes. Importantly, this parallels an IL-6-dependent

disruption of the growth hormone-insulin-like growth factor (GH-IGF) axis that

is characterized by decreased GH, IGFI and IGFBP3 levels. In addition, we

observe an IL-6-dependent induction in pro-lactin-like protein-K (PLP-K)

expression as well as MIA-related alterations in other placental endocrine

factors. Together, these IL-6-mediated effects of MIA on the placenta represent

an indirect mechanism by which MIA can alter fetal development