Summary:
A new mouse study from Cold Spring Harbor Laboratory (CSHL) shows that maternal immune activation during a narrow gestational window can trigger autism-like developmental disruptions that affect only male fetuses. The team traced this male-specific vulnerability to damage of spongiotrophoblast cells in the placenta, indicating that failure of placental immune tolerance—occurring before sexual differentiation of the brain—may help explain the higher incidence of autism spectrum disorder (ASD) in males.
Key Facts:
- Critical 24-hour window: Immune activation at embryonic day 12.5 (E12.5) produced developmental abnormalities in about one-third of exposed fetuses within 24 hours, the earliest signs of disruption observed after maternal inflammation.
- Male-only susceptibility: Across experiments, autism-like developmental features appeared exclusively in male fetuses; female littermates exposed to the same maternal inflammation developed normally.
- Placental barrier breakdown: The vulnerability correlated with structural and functional damage to spongiotrophoblasts, specialized placental border cells that normally maintain maternal-fetal immune tolerance.
Source: Cold Spring Harbor Laboratory (CSHL)
While inherited genetic risk explains much of ASD liability, environmental influences during pregnancy are known contributors. Maternal immune activation (MIA)—an inflammatory response triggered by infection—has been repeatedly associated with elevated neurodevelopmental risk. Nevertheless, how maternal inflammation breaches fetal defenses, why only some pregnancies are affected, and why ASD diagnoses are more common in males have remained open questions.
The CSHL team approached these questions by mapping gestational inflammation at high temporal precision in a mouse model. Instead of focusing solely on the fetal brain, the researchers examined the placenta as a central mediator of maternal–fetal interactions. Their results point to a placenta-centered mechanism: maternal inflammation can erode placental immune tolerance, producing acute developmental deficits in a subset of male embryos.
A Critical Window for Gestational Disruption
To determine when the fetus is most vulnerable, investigators simulated viral-like immune challenges at several defined stages of pregnancy using poly(I:C), an immune-stimulating mimetic that activates inflammatory pathways without a live infection. They identified embryonic day 12.5 (E12.5) as the vulnerable window. At this stage, roughly 30% of embryos developed detectable teratogenic changes—such as reduced fetal weight and altered sensory organ development—within 24 hours of maternal immune activation.
This rapid onset of abnormalities marks the earliest disruption yet observed following maternal inflammation in this model, emphasizing the importance of narrow temporal windows when maternal immune events can have large impacts on fetal development.
Pre-hormonal Male Vulnerability
A striking outcome of the study is that abnormalities appeared exclusively in male embryos; female littermates exposed to identical maternal inflammation showed no comparable developmental disruptions. Because this divergence arises at E12.5—before the major sex steroid surges that drive sexual differentiation—the findings challenge explanations that attribute male bias in ASD primarily to later hormonal effects. Instead, they point to sex-specific differences present well before hormonal-driven brain differentiation.
The results suggest male embryos might present unique molecular signatures at the maternal-fetal interface that provoke adverse maternal immune responses during systemic inflammation, whereas female embryos appear to possess protective features that preserve placental integrity.
Spongiotrophoblasts: The Placental Fault Line
To identify the cellular basis of male-specific vulnerability, the team turned to the placenta, the organ responsible for nutrient exchange, gas transfer, and immunological protection of the fetus. Their analyses highlighted spongiotrophoblasts—fetally derived cells that help form the maternal-fetal border.
In unaffected pregnancies, this junction remained robust. In affected males, spongiotrophoblasts showed clear signs of cellular damage, down-regulation of extracellular matrix and hormone biosynthesis pathways, and loss of barrier properties. As placental structure broke down, immune cells and cytokines accumulated in the amniotic fluid. One cytokine in particular, interleukin-6, was necessary for the developmental abnormalities to emerge in this model.
These observations indicate that MIA can rapidly shift the maternal-fetal interface from an immunosuppressive to a proinflammatory state in a vulnerable subset of male embryos, producing acute, sex-restricted developmental deficits. Understanding how female placentas resist this shift could reveal protective mechanisms and therapeutic targets to reduce fetal vulnerability.
The Cheadle laboratory is now dissecting the molecular pathways that differ between male and female placental cells during MIA, with the goal of identifying interventions that preserve placental immune tolerance and prevent downstream neurodevelopmental consequences.
Editorial Notes:
- Article edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context provided by editorial staff.
About this Autism Research:
- Media Contact: Gina DiPietro
- Source: CSHL
- Image Credit: Image credited to Cheadle lab/CSHL
- Original Research (open access): Science Advances (September 16, 2026). Title: “Maternal-fetal immune conflict contributes to male-specific impairments in a mouse model of neurodevelopmental disorders.” Authors: Irene Sanchez-Martin, Bharti Kukreja, Paige Henderson, Qianyu Lin, Daniel DiMartino, Valerie Bagan, Justin Park, Brian T. Kalish, and Lucas Cheadle.
- DOI: 10.1126/sciadv.aeg0779
Abstract
Maternal-fetal immune conflict contributes to male-specific impairments in a mouse model of neurodevelopmental disorders
Autism spectrum disorder arises from a combination of genetic and environmental factors. Maternal immune activation (MIA) during pregnancy—when an infection triggers maternal inflammation—has been linked to increased ASD risk in offspring and appears to affect males disproportionately. The mechanisms that produce this male-specific vulnerability and how inflammatory signals cross the maternal-fetal interface to impact the male embryo have been unclear.
Using the poly(I:C) mouse model, researchers characterized fetal, placental, and amniotic changes within 24 hours of MIA. They observed that roughly 30% of embryos developed large-scale abnormalities, while 70% remained unaffected. These defects occurred only in a subset of male embryos and not in females.
Single-nucleus transcriptomics revealed strong induction of proinflammatory gene programs in the placentas of affected males, especially in spongiotrophoblasts. These cells down-regulated extracellular matrix and hormone biosynthesis pathways as placental integrity failed and immune components accumulated in the amniotic fluid. Interleukin-6 was required for the observed MIA-evoked developmental abnormalities.
The data indicate that MIA can rapidly convert the maternal-fetal interface from immunosuppressive to proinflammatory in a vulnerable subset of male embryos, causing acute, sex-restricted developmental deficits. The authors propose that male embryos may express distinct proteins that trigger the inflammatory response; combined with MIA-induced loss of maternal immunosuppression, this selectively disrupts male embryonic development.