Interleukin-1β Transfer across the Blood–Brain Barrier in the Ovine Fetus

Abstract

Pro-inflammatory cytokines contribute to hypoxic-ischemic brain injury. Blood-brain barrier (BBB) dysfunction represents an important component of hypoxic-ischemic brain injury in the fetus. Hypoxic-ischemic injury could accentuate systemic cytokine transfer across the fetal BBB. There has been considerable conjecture suggesting that systemic cytokines could cross the BBB during the perinatal period. Nonetheless, evidence to support this contention is sparse. We hypothesized that ischemia-reperfusion increases the transfer of systemic interleukin-1β (IL-1β) across the BBB in the fetus. Ovine fetuses at 127 days of gestation were studied 4 hours after 30 minutes of bilateral carotid artery occlusion and compared with a nonischemic group. Recombinant ovine IL-1β protein was expressed from an IL-1β pGEX-2 T vector in E. coli BL-21 cells and purified. The BBB function was quantified in 12 brain regions using a blood-to-brain transfer constant with intravenous 125 I-radiolabeled IL-1β ( 125 I-IL-1β). Interleukin-1β crossed the intact BBB in nonischemic fetuses. Blood-to-brain transport of 125 I-IL-1β was higher (P o0.05) across brain regions in fetuses exposed to ischemia-reperfusion than nonischemic fetuses. We conclude that systemic IL-1β crosses the intact fetal BBB, and that ischemia-reperfusion increases transfer of this cytokine across the fetal BBB. Therefore, altered BBB function after hypoxia-ischemia facilitates entry of systemic cytokines into the brain of the fetus.

Ischemic-Reperfusion Injury Increases Matrix Metalloproteinases and Tissue Metalloproteinase Inhibitors in Fetal Sheep Brain

“…We have previously shown direct linear correlations between integrated optical density (IOD) values normalized to the IC samples and those normalized to β-actin, when one age group was studied, e.g., newborn lambs [38]. In addition, we have compared claudin-3 expression normalized as the ratio to the IC standard with values normalized as ratios to vinculin and found that the values demonstrated an excellent correlation [31]. Therefore, experimental autoradiographic values are expressed as IOD ratios to the IC samples in order to normalize comparisons between the different groups and immunoblots.…”

“…We examined the cerebral cortex as it represents an important brain region, and because we had residual frozen frontal cerebral cortical samples from our previous studies [4,[29][30][31]. We have recently published a detailed schematic that we have used for our brain sample preparation in similar studies [32].…”

“…A coronal brain section of another half of the fetal brain was obtained at the level of the hypothalamus (mammillary bodies) for histopathological analysis [32]. The residual frozen brain from the frontal cortex was saved and used in prior publications [4,29,31,32] and for the current study in order to maximize information obtained from this complex large animal resource. Unfortunately, although we have previously measured BBB permeability and tight junction proteins in some of the fetal sheep reported in the current study, we did not have sufficient residual tissue remaining from the sham control animals.…”

“…The BBB transfer constant (K i ) used in the present study was from the same cohort of animals reported in our previous studies [4,29,31] and was measured with the BBB tracer α-[…”

Research progress of relationship between hyptoxic ischemic encephalopathy and interleukin in neonates

“…The study results of Ma Z et al [9] showed that umbilical cord blood mononuclear cell transplantation combined with hyperbaric oxygen therapy could reduce the expression of IL-1β and TNF-α protein, improve the long-term behavioral ability of hypoxic ischemic neonatal rats and alleviate brain damage. In Sadowska's study, [10] proinflammatory cytokines are involved in inflammatory reaction of hypoxic-ischemic brain damage, and blood brain barrier dysfunction is an important part of fetal hypoxicischemic brain damage. In this case, IL-1β passed through the intact fetal blood-brain barrier, and ischemia/reperfusion also enhanced the possibility of cytokines entering into the blood-brain barrier, resulting in brain injury.…”