Sustained Endocannabinoid Signaling Compromises Decidual Function and Promotes Inflammation-induced Preterm Birth

Abstract

Recent studies provide evidence that premature maternal decidual senescence resulting from heightened mTORC1 signaling is a cause of preterm birth (PTB). We show here that mice devoid of fatty acid amide hydrolase (FAAH) with elevated levels of N-arachidonyl ethanolamide (anandamide), a major endocannabinoid lipid mediator, were more susceptible to PTB upon lipopolysaccharide (LPS) challenge. Anandamide is degraded by FAAH and primarily works by activating two G-protein-coupled receptors CB1 and CB2, encoded by Cnr1 and Cnr2, respectively. We found that Faah ؊/؊ decidual cells progressively underwent premature senescence as marked by increased senescence-associated ␤-galactosidase (SA-␤-Gal) staining and ␥H2AX-positive decidual cells. Interestingly, increased endocannabinoid signaling activated MAPK p38, but not p42/44 or mTORC1 signaling, in Faah ؊/؊ deciduae, and inhibition of p38 halted premature decidual senescence. We further showed that treatment of a long-acting anandamide in wild-type mice at midgestation triggered premature decidual senescence utilizing CB1, since administration of a CB1 antagonist greatly reduced the rate of PTB in Faah ؊/؊ females exposed to LPS. These results provide evidence that endocannabinoid signaling is critical in regulating decidual senescence and parturition timing. This study identifies a previously unidentified pathway in decidual senescence, which is independent of mTORC1 signaling.

Pregnancy success in mice requires appropriate cannabinoid receptor signaling for primary decidua formation

“…Since most uterine epithelial cells are removed in implantation sites on day 8, we attribute the increase to changes in stromal/decidual cells. We isolated and purified uterine stromal cells on day 4 of pregnancy and induced them to decidualize in vitro by hormone treatments according to our established protocol ( Sun et al, 2016 ). Levels of Cnr1 increased about threefold in WT and Cnr2 -/- decidualizing cells as compared to non-decidualized stromal cells in each genotype ( Figure 6b ).…”

“…In vitro decidualization of mouse stromal cells. Stromal cells were collected by enzymatic digestion of mouse uteri on day 4 of pregnancy as described previously (22).…”

“…Stromal cells were collected by enzymatic digestion of mouse uteri on day 4 of pregnancy as described previously ( Sun et al, 2016 ). The cells were cultured in phenol-red free DMEM/F12 medium supplemented with charcoal-stripped 1% FBS ( w / v ) overnight before the initiation of decidualization by treatment of estradiol (10 nM) and medroxyprogesterone acetate (1 μM) for 6 d.…”

Pregnancy success in mice requires appropriate cannabinoid receptor signaling for primary decidua formation

“…In vitro decidualization of mouse stromal cells. Stromal cells were collected by enzymatic digestion of mouse uteri on day 4 of pregnancy as described previously (21).…”

“…Since most uterine epithelial cells are removed in implantation sites on day 8, we attribute the increase to changes in stromal/decidual cells. We isolated and purified uterine stromal cells on day 4 of pregnancy and induced them to decidualize in vitro by hormone treatments according to our established protocol (21). Levels of Cnr1 increased about 3-fold in WT and Cnr2 -/decidualizing cells as compared to non-decidualized stromal cells in each genotype (Fig 6b).…”