Project description:Mechanisms underlying in utero fetal lung injury remain poorly defined, and a greater understanding of pathways regulating these processes may lead to novel therapies that prevent lung injury before birth. MicroRNAs (miRNAs) are small non-coding, endogenous RNAs that regulate gene expression and have been implicated in the pathogenesis of lung disease. We sought to determine whether differentially expressed miRNAs in the fetal lung following choriodecidual infection are associated with elevation of amniotic fluid (AF) cytokine levels and acute lung injury in a nonhuman primate model. After inoculating ten chronically catheterized pregnant monkeys (Macaca nemestrina) at 118-125 days gestation (term=172 days) with either Group B Streptococcus (GBS) 1 x 106 colony forming units (n=5) or saline (n=5) in the choriodecidual space, we extracted fetal lung mRNA and miRNA and profiled changes in expression. We identified 9 differentially expressed miRNAs (p<0.05, >1.5 fold change) in the GBS-exposed fetal lungs by microarray, but of these only miR-155-5p was significantly elevated by qRT-PCR (p=0.016). The microarray log2 intensity of miR-155-5p positively correlated with fetal lung injury scores and AF IL-1? and TNF-??levels (R2=0.54, p=0.016). In situ hybridization revealed that miR-155-5p is expressed throughout the fetal lung, which led us to investigate mechanisms that regulate miR-155-5p expression. Significantly elevated miR-155-5p expression was observed when immortalized human fetal airway epithelial (FeAE) cells were exposed to IL-6 and TNF-??. Overexpression of miR-155-5p in FeAE cells increased production of IL-6, CCL5/RANTES and CXCL10/IP-10. Using a luciferase reporter assay, we validated FGF9 as an authentic target of miR-155-5p, which is essential to development of the lung mesenchyme and distal epithelial branching. Collectively, these results suggest that a choriodecidual inflammatory response leads to increased AF cytokine levels, which induce miR-155-5p expression. In turn, miR-155-5p activates and recruits leukocytes (IL-6, CCL5/RANTES) and inhibits fetal lung angiogenesis (CXCL10/IP-10), meschenchymal development and epithelial branching (targets FGF9 mRNA). A therapy to antagonize miR-155-5p may ameliorate perinatal lung injury.

Project description:Mechanisms underlying in utero fetal lung injury remain poorly defined, and a greater understanding of pathways regulating these processes may lead to novel therapies that prevent lung injury before birth. MicroRNAs (miRNAs) are small non-coding, endogenous RNAs that regulate gene expression and have been implicated in the pathogenesis of lung disease. We sought to determine whether differentially expressed miRNAs in the fetal lung following choriodecidual infection are associated with elevation of amniotic fluid (AF) cytokine levels and acute lung injury in a nonhuman primate model. After inoculating ten chronically catheterized pregnant monkeys (Macaca nemestrina) at 118-125 days gestation (term=172 days) with either Group B Streptococcus (GBS) 1 x 106 colony forming units (n=5) or saline (n=5) in the choriodecidual space, we extracted fetal lung mRNA and miRNA and profiled changes in expression. We identified 9 differentially expressed miRNAs (p<0.05, >1.5 fold change) in the GBS-exposed fetal lungs by microarray, but of these only miR-155-5p was significantly elevated by qRT-PCR (p=0.016). The microarray log2 intensity of miR-155-5p positively correlated with fetal lung injury scores and AF IL-1? and TNF-??levels (R2=0.54, p=0.016). In situ hybridization revealed that miR-155-5p is expressed throughout the fetal lung, which led us to investigate mechanisms that regulate miR-155-5p expression. Significantly elevated miR-155-5p expression was observed when immortalized human fetal airway epithelial (FeAE) cells were exposed to IL-6 and TNF-??. Overexpression of miR-155-5p in FeAE cells increased production of IL-6, CCL5/RANTES and CXCL10/IP-10. Using a luciferase reporter assay, we validated FGF9 as an authentic target of miR-155-5p, which is essential to development of the lung mesenchyme and distal epithelial branching. Collectively, these results suggest that a choriodecidual inflammatory response leads to increased AF cytokine levels, which induce miR-155-5p expression. In turn, miR-155-5p activates and recruits leukocytes (IL-6, CCL5/RANTES) and inhibits fetal lung angiogenesis (CXCL10/IP-10), meschenchymal development and epithelial branching (targets FGF9 mRNA). A therapy to antagonize miR-155-5p may ameliorate perinatal lung injury. Ten chronically catheterized pregnant monkeys (Macaca nemestrina) at 118-125 days gestation (term=172 days) received choriodecidual inoculation of either: 1) Group B Streptococcus (n=5) or 2) saline (n=5). Cesarean section and fetal necropsy was performed in the first week after GBS or saline inoculation regardless of labor. RNA was extracted from fetal lungs and profiled by microarray. Results were analyzed using single gene, Gene Set, and Ingenuity Pathway Analysis. Validation was by RT-PCR and immunohistochemistry.

Project description:BackgroundIntrauterine exposure to amniotic fluid (AF) cytokines is thought to predispose to bronchopulmonary dysplasia (BPD). We evaluated the effects of GBS exposure on RNA expression in fetal lung tissue to determine early molecular pathways associated with fetal lung injury that may progress to BPD.MethodsTen chronically catheterized pregnant monkeys (Macaca nemestrina) at 118-125 days gestation (term?=?172 days) received choriodecidual inoculation of either: 1) Group B Streptococcus (n?=?5) or 2) saline (n?=?5). Cesarean section and fetal necropsy was performed in the first week after GBS or saline inoculation regardless of labor. RNA was extracted from fetal lungs and profiled by microarray. Results were analyzed using single gene, Gene Set, and Ingenuity Pathway Analysis. Validation was by RT-PCR and immunohistochemistry.ResultsDespite uterine quiescence in most cases, fetal lung injury occurred in four GBS cases (intra-alveolar neutrophils, interstitial thickening) and one control (peri-mortem hemorrhage). Significant elevations of AF cytokines (TNF-?, IL-8, IL-1?, IL-6) were detected in GBS versus controls (p<0.05). Lung injury was not directly caused by GBS, because GBS was undetectable by culture and PCR in the AF and fetal lungs. A total of 335 genes were differentially expressed greater than 1.5 fold (p<0.05) with GBS exposure associated with a striking upregulation of genes in innate and adaptive immunity and downregulation of pathways for angiogenesis, morphogenesis, and cellular growth and development.ConclusionsA transient choriodecidual infection may induce fetal lung injury with profound alterations in the genetic program of the fetal lung before signs of preterm labor. Our results provide a window for the first time into early molecular pathways disrupting fetal lung angiogenesis and morphogenesis before preterm labor occurs, which may set the stage for BPD. A strategy to prevent BPD should target the fetus in utero to attenuate alterations in the fetal lung genetic program.

Dataset Information

Choriodecidual Group B Streptococcal Infection Induces miR-155-5p in the Fetal Lung in Macaca nemestrina.

Publications

Choriodecidual Group B Streptococcal Infection Induces miR-155-5p in the Fetal Lung in Macaca nemestrina.

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