Gestational benzene exposure programs sex-specific neuroimmune responses to postnatal viral infection.

Background: Benzene is a widespread volatile organic compound, but its effects on fetal neuroimmune development remain poorly defined. We tested whether continuous gestational benzene exposure alters fetal placenta-brain signaling, fetal brain myeloid phenotype, and selected postnatal responses to viral challenge. Methods: Pregnant C57BL/6 mice were exposed to filtered air or 5 ppm benzene continuously from E0.5 to E12.5 or E17.5. Fetal tissues were collected at the respective endpoints. A separate cohort exposed through E17.5 delivered naturally; offspring received MHV68 at PND10 and were analyzed at PND17. We assessed fetal morphometry, sex-stratified transcriptomic and qPCR profiles, and brain myeloid-cell phenotypes. Results: Benzene exposure was associated with a female-specific reduction in occipitofrontal diameter at E12.5 that was not detected at E17.5. Transcriptomic and qPCR analyses identified sex-dependent differences at the two fetal collection endpoints in developmental, immune, and GPCR-linked signaling pathways. At E17.5, benzene exposure reduced EGR2 and increased MHC II in fetal brain myeloid/microglia-enriched cells in both sexes. At PND17 after MHV68 challenge, prenatally exposed males had higher brain ORF65 and Conclusions: Continuous gestational benzene exposure was associated with sex-dependent alterations in fetal neuroimmune measures and selected postnatal responses to viral challenge. Because the E12.5 and E17.5 cohorts differed in developmental age, cumulative exposure duration, and neural tissue collected (fetal head versus fetal brain), the study does not identify a discrete gestational window of susceptibility.