Effects of fetal haemoglobin on systemic oxygenation in preterm infants and the development of retinopathy of prematurity PacIFiHER Report No. 2.

BACKGROUND/AIMS: Fetal haemoglobin (HbF) has an oxyhaemoglobin dissociation curve that may affect systemic oxygenation and the development of retinopathy of prematurity (ROP). The study aim is to characterise the effects of HbF levels on systemic oxygenation and ROP development. METHODS: Prospective study conducted from 1 September 2017 through 31 December 2018 at the Johns Hopkins NICU. Preterm infants with HbF measured at birth, 31, 34 and 37 weeks post-menstrual age (PMA), complete blood gas and SpO2 recorded up to 42 weeks PMA, and at least one ROP exam were included. RESULTS: Sixty-four preterm infants were enrolled. Higher HbF was associated with significantly higher SpO2, lower PCO2, lower FiO2 from birth to 31 weeks PMA and 31 to 34 weeks PMA (rs=0.51, rs=-0.62 and rs=-0.63; p<0.0001 and rs=0.71, rs=-0.58 and rs=-0.79; p<0.0001, respectively). To maintain oxygen saturation goals set by the neonatal intensive care unit, higher median FiO2 was required for HbF in the lowest tercile from birth compared with HbF in the highest tercile to 31 weeks and 31 to 34 weeks PMA; FiO2=35 (21-100) versus 21 (21-30) p<0.006 and FiO2=30 (28-100) versus 21 (21-30) p<0.001, respectively. Preterm infants with ROP had poorer indices of systemic oxygenation, as measured by median levels of SpO2 and PCO2, and lower levels of HbF (p<0.039 and p<0.0001, respectively) up to 34 weeks PMA. CONCLUSION: Low HbF levels correlated with poor oxygenation indices and increased risk for ROP. O2 saturation goals to prevent ROP may need to incorporate relative amount of HbF.

Lower foetal haemoglobin levels at 31- and 34-weeks post menstrual age is associated with the development of retinopathy of prematurity : PacIFiHER Report No. 1 PacIFiHER Study Group (Preterm Infants and Fetal Haemoglobin in ROP).

BACKGROUND/OBJECTIVES: Previous studies have suggested that lower mean foetal haemoglobin (HbF) levels is associated with an increased risk for developing retinopathy of prematurity (ROP). Lower HbF levels may lead to high oxygen exposure to the developing retina thereby increasing the risk of acute ROP. In this study, we characterize the temporal relationship of HbF levels and the development of ROP. SUBJECTS/METHODS: This is a single institution prospective observational cohort study. Preterm infants (born <31 weeks gestational age or <1500 g) with HbF measured at birth (cord blood), 31-, 34-, and 37-weeks post menstrual age (PMA); and at least one ROP exam, were enrolled. RESULTS: A total of 60 preterm infants (28 females, 47%) were enrolled. At 31-, 34-, 37-weeks PMA, infants with ROP (mild = Type 2 or less severe and severe = Type 1 ROP) had statistically lower percentages of HbF than infants with no ROP (28.2 ± 15 and 9.7 ± 2.9 vs 67.1 ± 29.6; p < 0.0001; 23.3 ± 14.7 and 32.5 vs 60.1 ± 25; p < 0.005; 31.9 ± 15.8 and 41.6 vs 60.2 ± 20.0; p < 0.0019). Infants with HbF levels in the lowest tercile at 31-weeks PMA were 7.6 times more likely to develop mild and severe ROP (95% CI 2.1-24.0, p value = 0.0006) and this risk increased to 12.3 times (95% CI: 2.6-59.0, p value = 0.0017) at 34-weeks PMA. CONCLUSIONS: Low HbF levels at 31- and 34-weeks PMA are associated with significantly increased risk of developing ROP. The decrease in HbF precedes the development of ROP and may be important in its pathogenesis.

Mouse Bone Marrow-Derived Mesenchymal Stem Cells Alleviate Perinatal Brain Injury Via a CD8+ T Cell Mechanism in a Model of Intrauterine Inflammation.

The objective of this study was to determine if mouse bone marrow-derived mesenchymal stem cells (BMMSCs) ameliorate preterm birth and perinatal brain injury induced by intrauterine inflammation (IUI). A mouse model of IUI-induced perinatal brain injury at embryonic (E) day 17 was utilized. BMMSCs were derived from GFP-transgenic mice and phenotypically confirmed to be CD44+, Sca-1+, CD45-, CD34-, CD11b-, and CD11c- by flow cytometry and sorted by fluorescence-activated cell sorting (FACS). Dams were assigned to four groups: phosphate-buffered saline (PBS) + PBS, PBS + BMMSCs, lipopolysaccharide (LPS) + PBS, and LPS + BMMSCs. Following maternal IUI, there was a significant increase in CD8+ T cells in the placentas. Maternally administered BMMSCs trafficked to the fetal side of the placenta and resulted in significantly decreased placental CD8+ T cells. Furthermore, fetal trafficking of maternally administered BMMSCs correlated with an improved performance on offspring neurobehavioral testing in LPS + BMMSC group compared with LPS + PBS group. Our data support that maternal administration of BMMSCs can alleviate perinatal inflammation-induced brain injury and improve neurobehavioral outcomes in the offspring via CD8+ T cell immunomodulation at the feto-placental interface.

Placental malperfusion in response to intrauterine inflammation and its connection to fetal sequelae.

Exposure to intrauterine inflammation (IUI) is associated with short- and long-term adverse perinatal outcomes. However, little data exist on utilizing placenta to prognosticate fetal injury in this scenario. Our study aimed to utilize imaging modalities to evaluate mechanisms contributing to placental injury following IUI exposure and correlated it to concomitant fetal brain injury. CD1 pregnant dams underwent laparotomies and received intrauterine injections of either lipopolysaccharide (LPS; a model of IUI) or phosphate-buffered saline (PBS). In utero ultrasound Doppler velocimetry of uterine and umbilical arteries and magnetic resonance imaging (MRI) of placental volumes with confirmatory immunohistochemical (vimentin) and histochemistry (fibrin) analyses were performed. ELISA for thrombosis markers, fibrinogen and fibrin was performed to analyze thrombi in placenta. Fetal brain immunohistochemistry was performed to detect microglial activation (ionized calcium-binding adaptor molecule 1, Iba1). On ultrasound, LPS group demonstrated elevated resistance indices, pulsatility indices and a greater occurrence of absent end-diastolic flow in the umbilical and uterine arteries. In the fetus, there was an increased cardiac Tei indices in the LPS group. MRI revealed decreased volume of placenta in the LPS group associated with placental thinning and placental endothelial damage on immunohistochemistry. Decreased fibrinogen content and more thrombi staining in placenta exposed to maternal LPS indicated the hypercoagulability. Furthermore, the expression of Iba1was significantly associated with placental thickness (r = -0.7890, Pearson correlation coefficient). Our data indicate that IUI can trigger events leading to maternal placental malperfusion and fetal vessel resistance, as well as predispose the developing fetus to cardiac dysfunction and brain damage. Furthermore, our data suggest that prenatal ultrasound can be a real-time clinical tool for assessing fetal risk for adverse neurologic outcomes following the potential IUI exposure.

Maternal Supplementation of Low Dose Fluoride Alleviates Adverse Perinatal Outcomes Following Exposure to Intrauterine Inflammation.

Maternal periodontal disease has been linked to adverse pregnancy sequelae, including preterm birth (PTB); yet, root planing and scaling in pregnancy has not been associated with improved perinatal outcomes. Fluoride, a cariostatic agent, has been added to drinking water and dental products to prevent caries and improve dental health. The objective of this study was to explore the effects of fluoride supplementation using a mouse model of preterm birth and perinatal sequalae. Pregnant mice were fed low dose fluoride (LF-) or high dose fluoride (HF-) and given intrauterine injections of lipopolysaccharide (LPS) or phosphate-buffered saline (PBS). We found that LPS + LF- significantly increased livebirths, pup survival, and litter size compared to LPS alone. Moreover, offspring from the LPS + LF- group exhibited significantly improved neuromotor performance and more neurons compared to those from the LPS group. Additionally, LF- treatment on human umbilical vein endothelial cells (HUVECs) increased cell viability and decreased oxidative stress after treatment with LPS. Collectively, our data demonstrates that maternal LF- supplementation during pregnancy postpones the onset of PTB, acts to increase the liveborn rate and survival time of newborns, and reduces perinatal brain injury in cases of intrauterine inflammation.

Maternal CD8+ T-cell depletion alleviates intrauterine inflammation-induced perinatal brain injury.

We investigated the mechanisms by which CD8+ T-cell trafficking in placenta contributes to perinatal brain injury by studying effects of maternal CD8+ T-cell depletion (DEP) in a mouse model of intrauterine inflammation (IUI). Maternal CD8+ T cells were depleted with anti-CD8+ antibodies. IUI was induced with lipopolysaccharide (LPS). DEP was confirmed using flow cytometry. Preterm birth rate was evaluated. Offspring neurologic sequelae were assessed by Nissl staining, immune arrays, confirmatory individual TaqMan® gene assays, and neurobehavioral tests. DEP did not significantly prevent LPS-induced preterm birth but improved neurobehavioral performance (P < .001) and increased cortical neuronal density (P < .05) in LPS-exposed pups compared to controls. These changes were associated with decreased CCL3 and CXCL10 and increased CCL5 in DEP LPS-exposed mice. We demonstrate that DEP reduces perinatal brain injury following IUI. This supports a role for maternal CD8+ T-cell trafficking in placenta in mediating perinatal brain injury separate from preterm birth mechanisms.