Fetal Tracheal Occlusion Increases Lung Basal Cells via Increased Yap Signaling

Fetal endoscopic tracheal occlusion (FETO) is an emerging surgical therapy for congenital diaphragmatic hernia (CDH). Ovine and rabbit data suggested altered lung epithelial cell populations after TO with transcriptomic signatures implicating basal cells. To test this hypothesis, we deconvolved mRNA-seq data and used quantitative image analysis in fetal rabbit lungs to showed increased basal cells and reduced ciliated cells after TO. In a fetal mouse TO model, flow cytometry showed increased basal cells, and immunohistochemistry demonstrated basal cell extension to the subpleura. Nuclear yap, a known regulator of basal cell fate, was increased in TO lung, and Yap ablation on the lung epithelium abrogated TO-mediated basal cell expansion. mRNA-seq of TO lung showed increased activity of downstream Yap genes. Human lung specimens with congenital and fetal endoscopic tracheal occlusion had clusters of subpleural basal cell that were not present in control. TO increases lung epithelial cell nuclear Yap leading to basal cell expansion.

Interleukin-18: A Novel Participant in the Occurrence, Development, and Drug Therapy of Obliterative Bronchiolitis Postlung Transplantation

Background. Obliterative bronchiolitis (OB) was a main cause of deterioration of long-term prognosis in lung transplant recipients after the first posttransplant year. Proinflammatory cytokine interleukin-18 (IL-18) strengthened both the natural immunity and acquired immunity and played an important role in organ transplantation. The roles of IL-18 in the occurrence, development, and drug treatment of OB remained unclear. Methods. Small interfering RNA (siRNA) against mouse IL-18 (siRNA-IL-18) was used to silence IL-18 expression. Mouse heterotopic tracheal transplantation model was used to simulate OB. Recipient mice were divided into 5 groups ( n = 12 ) according to donor mouse strains and drug treatment: isograft group, allograft group, allograft+tacrolimus group, allograft+azithromycin group, and allograft+tacrolimus+azithromycin group. The luminal obliteration rates were pathological evaluation. Expressions of cytokines and MMPs were detected by real-time PCR, western blot, and enzyme chain immunosorbent assay (ELISA). Results. The luminal obliteration rates of IL-18 of the siRNA-IL-18 group were significantly lower than those of the negative control group ( p < 0.0001 ) and the blank control group ( p = 0.0002 ). mRNA expressions of IFN-γ, EMMPRIN, MMP-8, and MMP-9 of the siRNA-IL-18 group were significantly lower than those of the negative and blank control groups. No tracheal occlusion occurred in grafts of the isograft group. The rates of tracheal occlusion of the allograft group, allograft+tacrolimus group, allograft+azithromycin group, and allograft+tacrolimus+azithromycin group were 72.17 ± 4.66 %, 40.33 ± 3.00 %, 38.50 ± 2.08 %, and 23.33 ± 3.24 %, respectively. There were significant differences between the 4 groups ( p < 0.001 ). Serum protein expressions of IL-17 ( p = 0.0017 ), IL-18 ( p = 0.0036 ), IFN-γ ( p = 0.0102 ), and MMP-9 ( p = 0.0194 ) were significantly decreased in the allograft+tacrolimus+azithromycin group compared to the allograft group. Conclusions. IL-18 could be a novel molecular involved in the occurrence, development, and drug treatment of OB.

Konjenital Diafragmatik Herni Tedavisinde Prenatal Dönemde Uygulanan Fetal Endoskopik Trakeal Oklüzyon İşleminin Etkinliği

Congenital diaphragmatic hernia is one of the rare malformations (0.8-5 / 10000). Although there are many treatment options in the postnatal period, as the severity of the malformation increases, the response to treatment decreases. Lung development is restricted by the compression of intraabdominal organs passing through the diaphragmatic defect. The severity of pulmonary hypertension due to hypoplasia in the lung tissue is closely related to postnatal morbidity and mortality. In addition to the lung tissue, left ventricular hypoplasia may also occur due to pressure on the heart. For all these reasons, treatment options have begun to be investigated even in the prenatal period, before tissue hypoplasia develops. In the last 20 years, there have been serious developments in ultrasound and magnetic resonance devices in parallel with the developments in technology. Accordingly, lung development of fetuses with diaphragmatic hernia during prenatal period has been better followed. Fetal endoscopic tracheal occlusion is the only method that can give treatment options to patients who are found to have severely decreased lung tissue in the prenatal period, in order to increase postpartum life expectancy. With this procedure, it is aimed to collect the fluids released from the lung with a balloon placed in the trachea in the prenatal period. Because of these accumulated fluids, the lung volume expands, tissue hypoplasia decreases, and the degree of pulmonary hypertension decreases. Although the fetal tracheal occlusion procedure has improved neonatal outcomes, there is a possibility of complications depending on the way the procedure is applied. Various complications such as premature rupture of membranes and preterm labor can be seen depending on the procedure. For this reason, it is necessary to choose the candidates for the tracheal occlusion procedure well and to calculate the profit-loss ratio well. In this study, current publications of fetal endoscopic tracheal occlusion procedure were reviewed. It was investigated on which patients the procedure could be applied and what the benefits and harms might be if it was applied.

Extracellular Vesicles and Their miRNA Content in Amniotic and Tracheal Fluids of Fetuses with Severe Congenital Diaphragmatic Hernia Undergoing Fetal Intervention

Infants with congenital diaphragmatic hernia (CDH) are at high risk of postnatal mortality due to lung hypoplasia and arterial pulmonary hypertension. In severe cases, prenatal intervention by fetal endoscopic tracheal occlusion (FETO) can improve survival by accelerating lung growth. However, postnatal mortality remains in the range of about 50% despite fetal treatment, and there is currently no clear explanation for this different clinical response to FETO. We evaluated the concentration of extracellular vesicles (EVs) and associated microRNA expression in amniotic and tracheal fluids of fetuses with CDH undergoing FETO, and we examined the association between molecular findings and postnatal survival. We observed a higher count of EVs in the amniotic fluid of non-survivors and in the tracheal fluid sampled in utero at the time of reversal of tracheal occlusion, suggesting a pro-inflammatory lung reactivity that is already established in utero and that could be associated with a worse postnatal clinical course. In addition, we observed differential regulation of four EV-enclosed miRNAs (miR-379-5p, miR-889-3p; miR-223-3p; miR-503-5p) in relation to postnatal survival, with target genes possibly involved in altered lung development. Future research should investigate molecular therapeutic agents targeting differentially regulated miRNAs to normalize their expression and potentially improve clinical outcomes.