MAIDE OZEN, Johns Hopkins University School of Medicine, Baltimore, MD, United States; Yuma Kitase, Johns Hopkins school of Medicine, Baltimore, MD, United States; Shenandoah Robinson, Johns Hopkins Children's Center, Baltimore, MD, United States; Lauren Jantzie, Johns Hopkins University School of Medicine, Baltimore, MD, United States
Assistant Professor Pediatrics Johns Hopkins University School of Medicine Baltimore, Maryland, United States
Background: Chorioamnionitis (CHORIO) induces sequential changes in the brain inflammatory immune signatures and increases Heme oxygenase-1 (HO-1)/Transferrin receptor-1 (TfR1) during a critical neurodevelopmental window. HO-1 and TfR1 are important in regulating cytokines, chemokines, differentiation of innate and adaptive immune cells. We previously determined alterations in brain inflammatory genes and immune cells in the early perinatal period, however the chronicity of these changes remain unknown. Objective: To determine if CHORIO induced T-cell inflammation is propagated by a sustained pro-inflammatory cytokine microenvironment following CHORIO at postnatal day 21 (P21), a toddler equivalent age. Design/Methods: Pregnant Sprague-Dawley rats were stratified to Sham or CHORIO on embryonic day (E)18. For CHORIO, after transient uterine artery occlusion, intra-amniotic lipopolysaccharide (LPS, 4 μg/sac) was injected. Shams received laparotomy with equal duration of anesthesia. At P21, we studied serum and brain cytokine and chemokines: IFN-γ, IL-1β, IL-4, IL-5, IL-6, KC/GRO, IL-10, IL-13 and TNF-α, and brain and peripheral blood T-cell subsets by flow cytometry. Data is presented as mean±SEM with statistical differences established with t-tests. Results: Notably, T-helper (Th) cells in CHORIO brains were increased compared to Sham (0.14±0.028% vs 0.05±0.03, p=0.019). Th cells in blood and T-cytotoxic cells in brain were similar. Concurrently, we detected a significant increase in the pro-inflammatory cytokine IL-6 (23.5±4.7 pg/100μg protein, n=7, p=0.048) in cortex obtained from CHORIO compared to Sham (n=7, 10.0±3.8) and a significant but less pronounced increase in the anti-inflammatory cytokine IL-10 (3.0±0.9 vs. 0.9±0.6, p=0.0344). Changes in brain cytokines were paralleled by serum increases in IL-6 (p=0.02), IL-10 (p=0.004), IFN-γ (p=0.001) and IL-1β (p=0.04) in CHORIO animals (n=7) compared to Sham (n=7).
Conclusion(s): CHORIO yields a sustained inflammatory microenvironment defined by increases in IL-6 in the cortex at P21, and the concurrent presence of Th predominant T-cells. Taken together, these data support Th specific neuroinflammation. Notably, HO-1/TfR1 is known to regulate the balance of IL-6 and IL-10 that is crucial for T-cell differentiation. Further studies to elucidate the role of dysregulated HO-1/TfR1 homeostasis in sustained T-cell neuroinflammation are warranted.
.jpg "Maide Ozen, MD photo")