Antenatal steroidCorticosteroids are used to improve lung function in infants who antenatale steroiden progressing toward BPD. Corticosteroids facilitate extubation, but there is conflicting information about adverse effects on esteroides para que sirven developing brain. An approach to minimizing risk is to use low dose, short duration treatments in the highest risk ventilator dependent patients. Questions remain about which corticosteroid is the safest and how to dose that corticosteroid. All who drink of this treatment recover in a short time, except those whom it does not help, who all antenatale steroiden. Therefore, it is obvious antenatale steroiden anteantale fails only in incurable cases.
Postnatal Corticosteroids for BPD
Patients at risk for preterm delivery are frequently administered both antenatal steroids for fetal maturation and magnesium sulfate for neuroprotection. In this study, we investigate whether steroids coadministered with magnesium sulfate preserve blood—brain barrier integrity in neuroinflammation.
Human umbilical vein endothelial cells were grown in astroglial conditioned media in a 2-chamber cell culture apparatus. Membrane integrity was assessed by zona occludens 1 ZO-1 immunoreactivity, permeability to fluorescently conjugated dextran, and transendothelial electrical resistance TEER.
Dexamethasone pretreatment alone or in combination with 0. Magnesium sulfate alone was not protective. This study supports a possible interaction between steroids and magnesium in neuroprotection. Neurodevelopmental disorders associated with preterm birth include motor deficits such as cerebral palsy, and cognitive deficits that are related to neuronal and axonal disease affecting the brain.
The risk of cerebral palsy increases as gestational age at delivery decreases 2 and with active infection such as chorioamnionitis. Inflammation is one of the principal causes of preterm birth and is a risk factor for the development of cerebral palsy in both preterm and term infants. Matrix metalloproteinases MMPs are proteases involved in development, tissue remodeling, and inflammation. Astrocytes, microglia, and neurons have all been shown to express MMPs, and their activity is markedly increased in the presence of trauma, which can lead to direct proteolytic breakdown of the blood—brain barrier.
The increased oxidative stressors seen in preterm infants may also lead to upregulation of MMP-9 with resultant disruption of the blood—brain barrier and cellular apoptosis. Because of the detrimental effect of inflammatory cytokines and proteases, prevention of neonatal brain injury may involve preservation of the neonatal blood—brain barrier. Both antenatal corticosteroids and magnesium sulfate are given to patients at risk for preterm delivery and may preserve the integrity of the neonatal blood—brain barrier.
Antenatal corticosteroids, given to promote fetal maturation, 18 also decrease the incidence of periventricular leukomalacia in preterm infants and reduce cytokine production in both the mother and the fetus. To differentiate among these mechanisms, we developed an in vitro model of the fetal microvasculature composing the blood—brain barrier to test the hypothesis that magnesium sulfate alone or in combination with dexamethasone can prevent cytokine-mediated blood—brain barrier degradation.
The purpose of our study was 2-fold. Research data were derived from a protocol approved by the Madigan Army Medical Center institutional review board.
The medium was changed to EndoGRO, and the cells were incubated 16 to 24 hours. Diagram of the in vitro blood—brain barrier model. A, HUVEC cells were seeded in a monolayer on the apical chamber of a 2-chamber cell culture apparatus B, C6 cell astroglial conditioned medium was applied to the top chamber, and membrane integrity was assessed by measuring the rate of fluorescent dye transit or TEER C.
D, Schematic of experimental design, including time and dose schedule for inhibitors. The HUVEC cells were plated onto the apical membrane of the 2-chamber apparatus, and C6 cells were plated in well format. Membrane permeability was assessed by measuring the diffusion of fluorescein isothiocyanate-conjugated dextran FITC-dextran across the membrane.
Scores were calculated at 0, 20, 60, , , and minutes after FITC-dextran addition. To assess changes in monolayer integrity after MMP-9, monolayers were conditioned 16 to 24 hours in C6 astroglial media. The culture medium was exchanged with fresh magnesium-free Dulbecco modified Eagle medium containing 1.
Low-dose concentrations of magnesium sulfate 0. The conditioning and treatment strategies are described in Figure 1D. Whole image level adjustments were made in the acquisition software, converted to TIFF format, and figures assembled using PhotoShop Elements 7.
Quantification of linear ZO-1 staining was accomplished. Images of HUVECs cultured in well plates and processed for immunofluorescence were analyzed for total ZO-1 length using a modified procedure described by Liu et al. The F test confirmed normal distribution of the data. Combination pretreatment with dexamethasone and low-dose magnesium sulfate 0. Neither magnesium dose alone affected permeability when treated with MMP-9 Figure 5B , middle and right panels.
B, Dexamethasone and 0. The ZO-1 immunocytochemistry was quantified by measuring ZO-1 length. There was no significant difference between vehicle and low-dose magnesium 0. Combination dexamethasone, low-dose magnesium 0.
Treatment with MMP-9 increased the permeability from 7. Monolayer integrity and tight junctions as measured by ZO-1 immunoreactivity were preserved only when magnesium was administered at low doses and in the presence of dexamethasone: Antenatal corticosteroids are routinely administered to women in preterm labor to promote fetal maturation.
Rouse, MD, written communication, May Crowther, MD, written communication, February Earlier studies support a role for antenatal steroids in reducing cerebral white matter lesions in very-low-birth-weight infants, 3 , 46 however, a connection between concomitant steroid administration and magnesium use has not been investigated.
Recent work from our laboratory supports direct inhibition of MMP-9 proteolytic activity by magnesium sulfate. The dose and timing of magnesium may have affected these results, and the timing of steroid and magnesium administration may also affect neuroprotection in the setting of inflammation-induced preterm labor.
Steroids and magnesium sulfate may need to be administered soon after infection or inflammatory insult to be effective, and lower doses of magnesium may be more effective with less potential fetal risk. We simulated neuroinflammation by applying inflammatory mediators with discrete cellular mechanisms of action at the level of the microvasculature comprising the blood—brain barrier: This discrepancy may relate to the discrete mechanisms of action of the 2 inflammatory mediators, including a dexamethasone-induced upregulation of TIMPs.
We plan to conduct future studies incorporating the major producers of inflammatory cytokines such as astrocytes, monocytes, and neutrophils into this model to investigate whether corticosteroids and magnesium affect blood—brain barrier integrity by inhibiting cytokine production in these cells.
The blood—brain barrier is a specialized layer of endothelial cells separating the blood from the brain parenchyma. Endothelial cell tight junctions maintain the low permeability and the high electrical resistance of the blood—brain barrier. Several cell line models have been reported in the literature for studying properties of the blood—brain barrier in vitro. Both primary cultures and cell lines have been proposed.
Although primary cultures from brain have higher TEER values exceeding ohm-cm 2 , these cells are more difficult to obtain and culture. Cell lines represent a viable alternative to using primary cultures. Both brain microvascular endothelial cells and astroglial-conditioned endothelial cell lines are well established in vitro models of the blood—brain barrier.
Both lines have been shown to develop a distinct network of functional endothelial cell tight junctions, low permeability to small molecules, and high TEER. Directly studying the human fetal blood—brain barrier presents obvious clinical and ethical challenges. In vitro models are often a necessary and useful first step to assert proof of principle and guide development of in vivo studies by enabling the isolation and investigation of specific cellular mechanisms.
Our study had several strengths and weaknesses. The strengths of our experimental approach include the use of an in vitro blood—brain barrier model to study in isolation the effects of specific inflammatory mediators and proteases on endothelial tight junctions. This allowed us to investigate a specific mechanism behind the effect of dexamethasone and magnesium both alone and in combination on blood—brain barrier integrity in the context of neuroinflammation.
The weaknesses of our study include the fact that our in vitro model of the neonatal blood—brain barrier is not as complex as the actual blood—brain barrier. Our initial data suggest that dexamethasone in combination with low-dose magnesium 0. Logistically, we were unable to collect both TEER and permeability for some combinations of treatments due to the number of experimental conditions. Our study of an in vitro model of the blood—brain barrier supports a role of antenatal steroids in the neuroprotective effect of magnesium in the context of neuroinflammation.
We recognize that steroids were given to a high percentage of women in the studies of magnesium for neuroprotection. In our model, we saw an effect with steroids and low-dose magnesium; therefore, it seems that timing and dosage of magnesium play critical roles in neuroprotection. These results support further investigation into a therapeutic window and the timing of combination steroid and magnesium treatment to optimize neuroprotection in preterm infants.
We gratefully acknowledge Ms Cindy Kirker for library support. The views expressed in this article are those of the author s and do not necessarily reflect the official policy or position of the Department of the Navy, Department of the Army, Department of Defense, or the United States Government.
Several of the authors are military service members. This work was prepared as part of their official duties. Declaration of Conflicting Interests: The online supplemental figures are available at http: National Center for Biotechnology Information , U.
Lutgendorf , MD, 1 Danielle L. Ippolito , PhD, 2 Mariano T. Dolinsky , MD, 1 and Peter G. Napolitano , MD 1. This article has been cited by other articles in PMC. Abstract Patients at risk for preterm delivery are frequently administered both antenatal steroids for fetal maturation and magnesium sulfate for neuroprotection.
Methods Research data were derived from a protocol approved by the Madigan Army Medical Center institutional review board. Open in a separate window. Conclusion Our study of an in vitro model of the blood—brain barrier supports a role of antenatal steroids in the neuroprotective effect of magnesium in the context of neuroinflammation. Supplementary Material Supplementary material: Brain injury in premature infants: Conde-Agudelo A, Romero R.
Antenatal magnesium sulfate for the prevention of cerebral palsy in preterm infants less than 34 weeks' gestation: Am J Obstet Gynecol. Possible antenatal and perinatal related factors in development of cystic periventricular leukomalacia.
The fetal inflammatory response syndrome. Amniotic fluid inflammatory cytokines interleukin-6, interleukin-1beta, and tumor necrosis factor-alpha , neonatal brain white matter lesions, and cerebral palsy.
Fetal exposure to an intra-amniotic inflammation and the development of cerebral palsy at the age of three years.
Intrauterine infection and the development of cerebral palsy. Interleukin-6 concentrations in umbilical cord plasma are elevated in neonates with white matter lesions associated with periventricular leukomalacia.