Prenatal Maternal Stress Causes Preterm Birth and Affects Neonatal Adaptive Immunity in Mice.

Maternal stress is a well-established risk factor for preterm birth and has been associated with adverse neonatal outcomes in the first and subsequent generations, including increased susceptibility to disease and lasting immunological changes. However, a causal link between prenatal maternal stress and preterm birth, as well as compromised neonatal immunity, has yet to be established. To fill this gap in knowledge, we used a murine model of prenatal maternal stress across three generations and high-dimensional flow cytometry to evaluate neonatal adaptive immunity. We report that recurrent prenatal maternal stress induced preterm birth in the first and second filial generations and negatively impacted early neonatal growth. Strikingly, prenatal maternal stress induced a systematic reduction in T cells and B cells, the former including regulatory CD4+ T cells as well as IL-4- and IL-17A-producing T cells, in the second generation. Yet, neonatal adaptive immunity gained resilience against prenatal maternal stress by the third generation. We also show that the rate of prenatal maternal stress-induced preterm birth can be reduced upon cessation of stress, though neonatal growth impairments persisted. These findings provide evidence that prenatal maternal stress causes preterm birth and affects neonatal immunity across generations, adverse effects that can be ameliorated upon cessation.

Human Chorionic Gonadotropin Has Anti-Inflammatory Effects at the Maternal-Fetal Interface and Prevents Endotoxin-Induced Preterm Birth, but Causes Dystocia and Fetal Compromise in Mice.

Human chorionic gonadotropin (hCG) is implicated in the maintenance of uterine quiescence by down-regulating myometrial gap junctions during pregnancy, and it was considered as a strategy to prevent preterm birth after the occurrence of preterm labor. However, the effect of hCG on innate and adaptive immune cells implicated in parturition is poorly understood. Herein, we investigated the immune effects of hCG at the maternal-fetal interface during late gestation, and whether this hormone can safely prevent endotoxin-induced preterm birth. Using immunophenotyping, we demonstrated that hCG has immune effects at the maternal-fetal interface (decidual tissues) by: 1) increasing the proportion of regulatory T cells; 2) reducing the proportion of macrophages and neutrophils; 3) inducing an M1 → M2 macrophage polarization; and 4) increasing the proportion of T helper 17 cells. Next, ELISAs were used to determine whether the local immune changes were associated with systemic concentrations of progesterone, estradiol, and/or cytokines (IFNgamma, IL1beta, IL2, IL4, IL5, IL6, IL10, IL12p70, KC/GRO, and TNFalpha). Plasma concentrations of IL1beta, but not progesterone, estradiol, or any other cytokine, were increased following hCG administration. Pretreatment with hCG prevented endotoxin-induced preterm birth by 44%, proving the effectiveness of this hormone as an anti-inflammatory agent. However, hCG administration alone caused dystocia and fetal compromise, as proven by Doppler ultrasound. These results provide insight into the mechanisms whereby hCG induces an anti-inflammatory microenvironment at the maternal-fetal interface during late gestation, and demonstrate its effectiveness in preventing preterm labor/birth. However, the deleterious effects of this hormone on mothers and fetuses warrant caution.

Vaginal progesterone, but not 17α-hydroxyprogesterone caproate, has antiinflammatory effects at the murine maternal-fetal interface.

OBJECTIVE: Progestogen (vaginal progesterone or 17-alpha-hydroxyprogesterone caproate [17OHP-C]) administration to patients at risk for preterm delivery is widely used for the prevention of preterm birth (PTB). The mechanisms by which these agents prevent PTB are poorly understood. Progestogens have immunomodulatory functions; therefore, we investigated the local effects of vaginal progesterone and 17OHP-C on adaptive and innate immune cells implicated in the process of parturition. STUDY DESIGN: Pregnant C57BL/6 mice received vaginal progesterone (1 mg per 200 µL, n = 10) or Replens (control, 200 µL, n = 10) from 13 to 17 days postcoitum (dpc) or were subcutaneously injected with 17OHP-C (2 mg per 100 µL, n = 10) or castor oil (control, 100 µL, n = 10) on 13, 15, and 17 dpc. Decidual and myometrial leukocytes were isolated prior to term delivery (18.5 dpc) for immunophenotyping by flow cytometry. Cervical tissue samples were collected to determine matrix metalloproteinase (MMP)-9 activity by in situ zymography and visualization of collagen content by Masson's trichrome staining. Plasma concentrations of progesterone, estradiol, and cytokines (interferon [IFN]γ, interleukin (IL)-1ß, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p70, keratinocyte-activated chemokine/growth-related oncogene, and tumor necrosis factor-α) were quantified by enzyme-linked immunosorbent assays. Pregnant mice pretreated with vaginal progesterone or Replens were injected with 10 µg of an endotoxin on 16.5 dpc (n = 10 each) and monitored via infrared camera until delivery to determine the effect of vaginal progesterone on the rate of PTB. RESULTS: The following results were found: (1) vaginal progesterone, but not 17OHP-C, increased the proportion of decidual CD4+ regulatory T cells; (2) vaginal progesterone, but not 17OHP-C, decreased the proportion of decidual CD8+CD25+Foxp3+ T cells and macrophages; (3) vaginal progesterone did not result in M1→M2 macrophage polarization but reduced the proportion of myometrial IFNγ+ neutrophils and cervical active MMP-9-positive neutrophils and monocytes; (4) 17OHP-C did not reduce the proportion of myometrial IFNγ+ neutrophils; however, it increased the abundance of cervical active MMP-9-positive neutrophils and monocytes; (5) vaginal progesterone immune effects were associated with reduced systemic concentrations of IL-1ß but not with alterations in progesterone or estradiol concentrations; and (6) vaginal progesterone pretreatment protected against endotoxin-induced PTB (effect size 50%, P = 0.011). CONCLUSION: Vaginal progesterone, but not 17OHP-C, has local antiinflammatory effects at the maternal-fetal interface and the cervix and protects against endotoxin-induced PTB.