Citations

ABSTRACT Objective Fetal surgery (FS) for spina bifida (SB) repair improves infant outcomes; however, spontaneous preterm birth (sPTB) is common. We aimed to evaluate maternal and fetal immune responses following FS for SB repair. Method Pregnant participants undergoing fetoscopic SB repair at 24–26 weeks of gestational age (GA) were prospectively recruited and compared to GA matched low‐risk controls. Blood samples were collected at baseline, 2‐week post‐surgery (POD14), and delivery. Cytokine analysis, flow cytometry, and T cell receptor (TCR) sequencing were performed. Results sPTB occurred in 5/6 of the FS group (0/6 of controls). Maternal blood in the FS group demonstrated increased alpha‐fetoprotein (AFP) and anti‐inflammatory IL‐1RA at baseline and POD14, increased pro‐inflammatory IL‐8 only post‐operatively, and elevated growth factors throughout. T cell phenotypes following FS revealed reduced TH17 frequency but increased activation receptors on cytotoxic T cells. At delivery, the FS cohort had reduced Th2 and Th17 helper T cells and CD4+ memory T cells, but CD8 T cells still showed increased activation. No TCR expansion was detected post‐surgery, suggesting antigen‐independent activation. Cord blood in FS repaired neonates had increased AFP, IL‐8, IL‐1RA. Conclusion Systemic immune changes following FS, particularly T cell maturation and activation, were observed. Further characterization of these mechanisms may help predict and prevent surgery‐induced PTB, improving outcomes.

The placenta is susceptible to infection by a number of viral pathogens, including severe acute respiratory syndrome coronavirus 2, which is associated with poor fetal outcomes. The histologic pattern of injury, termed severe acute respiratory syndrome coronavirus 2 placentitis, is characterized by a triad of increased perivillous fibrin deposition, intervillous histiocytes, and trophoblast necrosis. While the etiology of massive perivillous fibrin deposition (MPVFD) is mostly unknown, previous case reports of MPVFD in association with maternal Enterovirus (ENT) suggest that a subset of these cases are a consequence of undiagnosed viral infection. We evaluated 46 placentas collected between 2011 and 2022 with a diagnosis of MPVFD (n = 41) or chronic histiocytic intervillositis (CHI; n = 4). Combining methods of pan-viral metagenomic sequencing and targeted viral PCR, we detected Enterovirus DNA in 8 of 45 (18%) MPVFD and/or CHI cases. Seven of these positive cases were from MPVFD, and 1 was associated with a CHI diagnosis. Enterovirus A species (n = 7) were commonly identified, whereas one case had Enterovirus B. Histologic evaluation of these cases, including immunohistochemical staining for CD68, demonstrated increased intervillous histiocytes in Enterovirus-positive MPVFD cases in comparison with Enterovirus -negative, as well as evidence of trophoblast necrosis. Thus, we favor the terminology Enterovirus placentitis to describe this pathology. Overall, these findings suggest that Enterovirus is an underrecognized etiology of histologic MPVFD and, possibly, CHI. Further study to evaluate the recurrence risk of Enterovirus placentitis in comparison to MPVFD may help inform future fertility planning in patients with these diagnoses.

Abstract Despite intensive characterization of immune responses after COVID-19 infection and vaccination, research examining protective correlates of vertical transmission in pregnancy are limited. Herein, we profiled humoral and cellular characteristics in pregnant women infected or vaccinated at different trimesters and in their corresponding newborns. We noted a significant correlation between spike S1–specific IgG antibody and its RBD-ACE2 blocking activity (receptor-binding domain–human angiotensin-converting enzyme 2) in maternal and cord plasma (P < .001, R > 0.90). Blocking activity of spike S1–specific IgG was significantly higher in pregnant women infected during the third trimester than the first and second trimesters. Elevated levels of 28 cytokines/chemokines, mainly proinflammatory, were noted in maternal plasma with infection at delivery, while cord plasma with maternal infection 2 weeks before delivery exhibited the emergence of anti-inflammatory cytokines. Our data support vertical transmission of protective SARS-CoV-2–specific antibodies. This vertical antibody transmission and the presence of anti-inflammatory cytokines in cord blood may offset adverse outcomes of inflammation in exposed newborns.

Abstract Background Despite extensive studies of human immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) vaccination, research examining protective correlates of vertical transmission following maternal exposure in pregnancy remain limited. Here, we characterized antibody and cytokine responses in maternal and cord blood following infection or vaccination at various timepoints during gestation. Methods Spike S1 protein-specific binding antibodies and antibodies capable of blocking the interaction between the receptor binding domain (RBD) and the angiotensin converting enzyme 2 (ACE2) were measured in maternal and cord blood by ELISA. Serum concentrations of 74 cytokines/chemokines were measured by multiplex assay. Humoral responses and cytokine levels from matched maternal and fetal cord sera were compared and examined for potential correlations. Results We observed a highly significant correlation between Spike S1-specific antibody titer and RBD-ACE2 blocking antibody activity between maternal and fetal cord serum (p < 2.2e-16, R > 0.90). Blocking antibody activity was significantly higher for mothers infected during the 3rd trimester compared to earlier trimesters; however, vaccinated mothers developed and transferred higher antibody titers with greater RBD-ACE2 blocking antibody activity to their neonates than infected mothers. Furthermore, vaccine-induced Spike S1 IgG transfer ratios (fetal cord/maternal) were significantly higher than those induced by infection (p = 0.002). Multiplex assay showed significantly elevated levels of 33 cytokines/chemokines, mainly pro-inflammatory in infected maternal serum samples, while the paired fetal cord samples exhibited an anti-inflammatory cytokine predominance. Conclusion Our data support selective vertical transmission of potentially protective humoral responses against SARS-CoV-2, especially following vaccination in the 3rd trimester. The anti-inflammatory cytokine predominance in cord blood that persists despite maternal SARS-CoV-2 infection may offset the adverse outcomes of inflammation in pregnancy for the neonate. Disclosures All Authors: No reported disclosures.

Abstract Throughout gestation, the maternal immune system is tightly modulated to allow growth of a semiallogeneic fetus. During the third trimester, the maternal immune system shifts to a proinflammatory phenotype in preparation for labor. What induces this shift remains unclear. Cell-free fetal DNA (cffDNA) is shed by the placenta and enters maternal circulation throughout pregnancy. Levels of cffDNA are increased as gestation progresses and peak before labor, coinciding with a shift to proinflammatory maternal immunity. Furthermore, cffDNA is abnormally elevated in plasma from women with complications of pregnancy, including preterm labor. Given the changes in maternal immunity at the end of pregnancy and the role of sterile inflammation in the pathophysiology of spontaneous preterm birth, we hypothesized that cffDNA can act as a damage-associated molecular pattern inducing an inflammatory cytokine response that promotes hallmarks of parturition. To test this hypothesis, we stimulated human maternal leukocytes with cffDNA from primary term cytotrophoblasts or maternal plasma and observed significant IL-1β and CXCL10 secretion, which coincides with phosphorylation of IFN regulatory factor 3 and caspase-1 cleavage. We then show that human maternal monocytes are crucial for the immune response to cffDNA and can activate bystander T cells to secrete proinflammatory IFN-γ and granzyme B. Lastly, we find that the monocyte response to cffDNA leads to vascular endothelium activation, induction of myometrial contractility, and PGE2 release in vitro. Our results suggest that the immune response to cffDNA can promote key features of the parturition cascade, which has physiologic consequences relevant to the timing of labor.

Pregnancy loss affects approximately 20% of couples. The lack of a clear cause complicates half of all miscarriages. Early evidence indicates the maternal immune system and angiogenesis regulation are both key players in implantation success or failure. Therefore, this prospective study recruited women in the first trimester with known viable intrauterine pregnancy and measured blood levels of immune tolerance proteins galectin-9 (Gal-9) and interleukin (IL)-4, and angiogenesis proteins (vascular endothelial growth factors (VEGF) A, C, and D) between 5 and 9 weeks gestation. Plasma concentrations were compared between groups defined based on (a) pregnancy outcome and (b) maternal history of miscarriage, respectively. In total, 56 women were recruited with 10 experiencing a miscarriage or pregnancy loss in the 2nd or 3rd trimester and 11 having a maternal history or miscarriage. VEGF-C was significantly lower among women with a miscarriage or pregnancy loss. Gal-9 and VEGF-A concentrations were decreased in women with a prior miscarriage. Identification of early changes in maternal immune and angiogenic factors during pregnancy may be a tool to improve patient counseling on pregnancy loss risk and future interventions to reduce miscarriage in a subset of women.

AbstractProblemCell‐free fetal DNA (cffDNA) shed from the placenta can be detected in maternal blood and increases incrementally during gestation. Concentrations are further elevated with pregnancy complications. Specific activators of cffDNA release in such complications have not been identified. Here, we use trophoblast cells from early and term placenta to examine cffDNA release following apoptosis, infection, and sterile inflammatory stress.Method of StudyHTR8/SVneo cells were used to model first‐trimester trophoblasts, and term cytotrophoblasts (CTBs) were isolated from placentae collected after uncomplicated deliveries. Trophoblasts were treated with varying concentrations of doxorubicin (DOX), lipopolysaccharide (LPS), or high‐mobility group box protein 1 (HMGB1) for 18 h. Cells or supernatants were quantified for caspase‐3/7 cleavage, pro‐inflammatory cytokine secretion, and cffDNA release.ResultsBoth HTR8/SVneo and CTBs underwent caspase‐3/7 cleavage following DOX treatment, with HTR8/SVneo cells more sensitive to apoptosis than term CTBs. Apoptotic cells released more cffDNA in a dose‐dependent manner. Treatment with LPS resulted in an increase in pro‐inflammatory IL‐6 release, particularly in term CTBs compared to early trophoblasts; however, LPS did not affect cffDNA release. Lastly, while neither cell released more TNF‐α following stimulation with HMGB1, both HTR8/SVneo and CTBs released significantly more cffDNA in the presence of HMGB1.ConclusionsThese data show that apoptosis and sterile inflammation induced by DOX and HMGB1, respectively, cause an increase in cffDNA concentrations in both first‐trimester and term trophoblasts. Understanding physiologic release of cffDNA during healthy and complicated pregnancy can identify new targets for the diagnosis and treatment of gestational complications.