Maternal Inflammation in Late Gestation Alters Vaccine-Induced Immune Responses in Adult Murine Offspring

Abstract

BackgroundIntrauterine inflammation, commonly presenting as chorioamnionitis, is variably linked to preterm birth, neonatal infections and postnatal chronic inflammatory disorders. However, the effects of systemic maternal inflammation on exposed fetuses and offspring are less clear. We previously reported inflammatory responses in murine pups born after brief gestational exposure to experimental maternal inflammation. These findings led us to hypothesize that fetal exposure to maternal inflammation could lead to persistent alterations in postnatal immunity. ObjectiveTo test our hypothesis, we examined immune responses to vaccination, a useful measure of immune status, in young adult offspring with late gestational exposure to maternal LPS. Design/MethodsLate-gestation pregnant dams were treated with LPS or saline. Offspring (LPS-exposed or saline controls) were either immunized with the Tdap vaccine or remained unimmunized (naive mice), and were subsequently infected with Bordetella pertussis. Lung and spleen immune responses were assessed by multi-parameter flow cytometry, protein microarray and RT-PCR. ResultsWe observed that young adult (7 week old) mice exposed to maternal LPS during gestation, vaccinated with TDaP, and subsequently infected with pertussis exhibited lower lung neutrophil but higher CD4+ lymphocyte proportions relative to unexposed controls. In splenic studies, LPS-exposed mice had lower frequencies of CD4+IFN{psi}+ (Th1) and CD4+IL-17+ (Th17) cell populations. In vitro studies of post-vaccination responses to heat-killed B. pertussis showed variable levels of IL-2 and IL-4 in splenic cultures from LPS-exposed vs. control mice. Vaccinated, LPS-exposed mice showed variable splenic Stat3 and NFkb gene expression levels relative to those of naive LPS-exposed mice. ConclusionOur present murine studies show that experimental maternal inflammation during late gestation can alter immune response patterns to secondary challenge in young adult offspring. However, whether such intrauterine inflammatory exposure might also influence protective immune function remains to be determined. Our findings lead us to speculate that fetal exposure to systemic maternal inflammation in humans could have long-term implications for protective immunity.