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: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:Underdeveloped lungs are the primary cause of death in premature infants, however, little is known about stem and progenitor cell maintenance during human lung development. In this study, we have identified that FGF7, Retinoic Acid and CHIR-99021, a small molecule that inhibits GSK3 to activate Wnt signaling, support in vitro maintenance of primary human fetal lung bud tip progenitor cells in a progenitor state. Furthermore, these factors are sufficient to derive a population of human bud tip-like progenitor cells in 3D organoid structures from human pluripotent stem cells (hPSC). Functional studies showed that hPSC-derived bud tip progenitor organoids do not contain any mesenchymal cell types, maintain multilineage potential in vitro and are able to engraft into the airways of injured mice and respond to systemic factors. We performed RNA-sequencing to assess the degree of similarity in global gene expression profiles between the full human fetal lung (59-127 days gestation), isolated human fetal bud tip progenitors, organoids grown from primary fetal bud tip progenitors, and hPSC-derived bud tip organoids. Results showed that hPSC-derived organoids have molecular profiles similar to organoids generated from primary human fetal lung tissue. Gene expression differences between hPSC-derived bud tip organoids and fetal progenitor organoids may be related to the presence of contaminating mesenchymal cells in primary cultures. hPSC-derived bud tip organoids are generated from a well-defined human cell sources, offering a distinct advantage over rare primary tissue as a means to study human specific lung development, homeostasis and disease. Sample Nomenclature - Description ------------------------------------------------------------------------- Peripheral fetal lung the distal/peripheral portion of the fetal lung (i.e., distal 0.5 cm) was excised from the rest of the lung using a scalpel. This includes all components of the lung (e.g., epithelial, mesenchymal, vascular). Isolated fetal bud tip the bud peripheral portion of the fetal lung was excised with a scalpel and subjected to enzymatic digestion and microdissection. The epithelium was dissected and separated from the mesenchyme, but a small amount of associated mesenchyme likely remained. Fetal progenitor organoid 3D organoid structures that arose from culturing isolated fetal epithelial bud tips. Foregut spheroid 3D foregut endoderm structure as described in Dye et al. (2015). Gives rise to patterned lung organoid (PLO) when grown in 3F medium. Patterned lung organoid (PLO) lung organoids that were generated by differentiating hPSCs, as described throughout the manuscript. Bud tip organoid organoids derived from PLOs, enriched for SOX2/SOX9 co-expressing cells, and grown/passaged in 3F medium.

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Transciptomic profiling of human fetal lung samples

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