Maternal Lactobacillus Johnsonii Supplementation Does Not Protect Against Neonatal Sepsis-induced Mortality in C57Bl/6 Mice

Shiloh R. Lueschow, University of Iowa Stead Family Children's Hospital, Elmwood, IL, United States; Jennifer R. Bermick, University of Iowa, IA, United States

Background: Sepsis is a leading cause of morbidity and mortality in neonates despite improvement in clinical practice. This is attributed to the immune-deviant state of the neonatal immune system. Significant research has focused on probiotics to prevent late onset neonatal sepsis. Lactobacillus species are abundant in breast milk, and L. johnsonii (LJ) has been shown to attenuate respiratory syncytial virus infection and airway allergic sensitization by reprogramming the offspring immune system. We hypothesized that LJ supplementation of dams before and during pregnancy would have beneficial immune effects on the offspring and improved survival during neonatal sepsis.

Objectives: Our objectives were to determine the effect of maternal LJ supplementation on resultant pups' immune development and survival in neonatal sepsis.

Design/Methods: C57Bl/6 and BALB/C mice were included in this study as each strain demonstrates a distinct immune phenotype (Th1/pro-inflammatory and Th2/anti-inflammatory respectively). Female adult mice were gavaged with LJ (5x10^7 cfu) or PBS as a control for 7 days prior to mating and twice a week during mating and pregnancy. One set of P3-5 pups were infected with E. coli (10^3 cfu) IP to induce sepsis and followed for survival. CD11b+ splenic macrophages were harvested from a second set of P3-5 pups, cultured, and stimulated with heat-killed neonatal pathogens (E. coli or S. epidermidis). Cell culture supernatants were collected 24 hours after stimulation and cytokine levels were measured with a multiplexed protein assay.

Results: Pups from LJ supplemented C57Bl/6 dams had increased mortality, while pups from LJ supplemented BALB/C dams had improved survival compared to control pups (both p< 0.05). Pups from LJ supplemented C57Bl/6 dams had increased levels of the pro-inflammatory cytokines following bacterial stimulation (p < 0.05).

Conclusion: Pups from LJ supplemented C57Bl/6 dams had enhanced pro-inflammatory responses following bacterial stimulation and decreased survival during E. coli sepsis, demonstrating non-beneficial offspring immunomodulation. This contrasts with our BALB/C data demonstrating that LJ supplementation is protective in a neonatal sepsis model. The difference in immune skewing between the two mouse strains is likely a contributing factor to the difference in response. Future studies will investigate the effect of timing of probiotic administration (pre vs postnatal) and different probiotic strains on the offspring response to neonatal sepsis.