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Background: Intrauterine infection/inflammation can result in fetal and neonatal lung injury. However, the biological mechanisms of intrauterine infection/inflammation on fetal and neonatal lung injury and development are poorly known. To date, there are no reliable biomarkers for improving intrauterine infection/inflammation-induced lung injury. Methods: An animal model of intrauterine infection/inflammation-induced lung injury was established with pregnant Sprague–Dawley rats inoculated with Escherichia coli suspension. The intrauterine inflammatory status was assessed through the histological examination of the placenta and uterus. A serial of histological examinations of the fetal and neonatal rats lung tissues were performed. The fetal and neonatal rat lung tissues were harvested for next generation sequencing at embryonic day 17 and postnatal day 3, respectively. Differentially expressed mRNAs and lncRNAs were identified by conducting high-throughput sequencing technique. The target genes of identified differentially expressed lncRNAs were analyzed. Homology analyses for important differentially expressed lncRNAs were performed. Results: The histopathological results showed inflammatory infiltration, impaired alveolar vesicular structure, less alveolar numbers, and thickened alveolar septa in fetal and neonatal rat lung tissues. Transmission electron micrographs revealed inflammatory cellular swelling associated with diffuse alveolar damage and less surfactant-storing lamellar bodies in alveolar epithelial type II cells. As compared with the control group, there were 432 differentially expressed lncRNAs at embryonic day 17 and 125 differentially expressed lncRNAs at postnatal day 3 in the intrauterine infection group. The distribution, expression level, and function of these lncRNAs were shown in the rat genome. LncRNA TCONS_00009865, lncRNA TCONS_00030049, lncRNA TCONS_00081686, lncRNA TCONS_00091647, lncRNA TCONS_00175309, lncRNA TCONS_00255085, lncRNA TCONS_00277162, and lncRNA TCONS_00157962 may play an important role in intrauterine infection/inflammation-induced lung injury. Fifty homologous sequences in Homo sapiens were also identified. Conclusions: This study provides genome-wide identification of novel lncRNAs which may serve as potential diagnostic biomarkers and therapeutic targets for intrauterine infection/inflammation-induced lung injury. [ABSTRACT FROM AUTHOR]

Intrauterine infection is an important risk factor for bronchopulmonary dysplasia (BPD). BPD is characterized by arrested lung alveolarization and impaired pulmonary vascularization. The Notch4 signaling pathway is a key regulator of vascular remodeling and angiogenesis. Therefore, the presents study investigated the expression of Notch4, delta-like canonical Notch ligand 4 (Dll4) and related factors in an in vivo rat model and in rat pulmonary microvascular endothelial cells (PMVECs) in vitro, to study the mechanisms by which intrauterine infection affects rat lung development. A rat model of intrauterine infection was established by endocervical inoculation with Escherichia scoli on embryonic day 15. The date of birth was counted as postnatal day 0 (P0). Then, the lung tissues were collected from pups at days P3-P14. The expression of Notch4, Dll4 and related factors was measured by reverse transcription-quantitative PCR and western blotting. In addition, the γ-secretase inhibitor DAPT was used to examine the effect of Notch4 signaling on PMVECs. Intrauterine E. coli infection impaired normal lung development, as indicated by decreased microvessel density, fewer alveoli, fewer secondary septa, and larger alveoli compared with the control group. Furthermore, Notch4, Dll4 and NF-κB levels were significantly increased in the E. coli-infected group at P3 compared with the control group. Similarly, the mRNA expression levels of fetal liver kinase 1 (Flk-1, a VEGF receptor) were significantly increased in the E. coli-infected group at P3 and P7. In PMVECs, the inhibition of Notch4 signaling contributed to decreases in lipopolysaccharide (LPS)-induced expression of VEGF and its receptors. Furthermore, the inhibition of Notch4/Dll4 signaling accelerated cell proliferation and decreased the apoptosis rate of LPS-induced PMVECs. LPS-induced NF-κB expression in PMVECs was also attenuated by the Notch4/Dll4 inhibitor. In conclusion, intrauterine E. coli infection impaired normal lung development, possibly through Notch4/Dll4 signaling and effects on VEGF and its receptors. [ABSTRACT FROM AUTHOR]

Background: Intrauterine infection/inflammation plays an important role in the development of lung injury and bronchopulmonary dysplasia (BPD) in preterm infants, While a multifactorial genesis is likely, mechanisms involved in BPD after intrauterine infection/inflammation are largely unknown. Recent studies have suggested microRNAs (miRNAs) are likely to play a role. Therefore, this study aimed to study the effects and mechanisms of intrauterine infection/inflammation on lung development, and to identify miRNAs related to lung injury and BPD.Methods: An animal model of intrauterine infection/inflammation was established with pregnant SD rats endocervically inoculated with E.coli. The fetal and neonatal rats were observed at embryonic day (E) 17, 19, 21 and postnatal day (P) 1, 3, 7, 14, respectively. Body weight, lung weight, the expression levels of NLRP3, TNF-α, IL-lβ, IL-6, VEGF, Collagen I, SP-A, SP-B and SP-C in the lung tissues of fetal and neonatal rats were measured. Expression profiles of 1218 kinds of miRNAs in the lungs of neonatal rats were detected by miRNA microarray technique. Target genes of the identified miRNAs were predicted through online software.Results: Intrauterine infection/inflammation compromised not only weight development but also lung development of the fetal and neonatal rats. The results showed significantly increased expression of NLRP3, TNF-α, IL-1β, IL-6, Collagen I, and significantly decreased expression of VEGF, SP-A, SP-B and SP-C in the fetal and neonatal rat lung tissues in intrauterine infection group compared to the control group at different observation time point (P < 0.05). Forty-three miRNAs with significant differential expression were identified. Possible target genes regulated by the identified miRNAs are very rich.Conclusions: Intrauterine infection/inflammation results in lung histological changes which are very similar to those observed in BPD. Possible mechanisms may include NLRP3 inflammasome activation followed by inflammatory cytokines expression up-regulated, inhibiting the expression of pulmonary surfactant proteins, interfering with lung interstitial development. There are many identified miRNAs which target a wide range of genes and may play an important role in the processes of lung injury and BPD. [ABSTRACT FROM AUTHOR]