2012-08-012024-05-14https://scholars.lib.ntu.edu.tw/handle/123456789/656217摘要：早產兒呼吸窘迫症候群一直是影響早產兒死亡及罹病的一個主要原因，其發生率在出生週數介於24 到28 週的早產兒約在50-60%之間，而隨出生週數的增加而遞減。早產兒會發生早產兒呼吸窘迫症候群主要原因是因為肺臟不夠成熟而導致肺泡表面擴張劑(surfactant)的不足所引起。產前類固醇的使用，會促進早產兒肺臟的成熟，因此能預防或減輕早產兒呼吸窘迫症候群的發生機會。但是，類固醇的可能副作用包括感染胎兒生長遲緩、以及日後早產兒慢性肺疾病的發生一直是被大家所討論的話題。最近，Compernolle 等人在動物實驗上發現HIF-2α 以及他的下游基因血管內皮生長因子（VEGF）對肺臟的成熟很重要。而且，不管是子宮內注射或從氣管給予早產小鼠VEGF 都能有效地減輕呼吸窘迫症侯群的症狀。但是，子宮內注射VEGF 可能因此導致早產，而直接給與母親VEGF，會因VEGF 的分子量很大無法通過胎盤而失去對胎兒的作用。因此，找到一個能調控胎鼠肺臟VEGF 表現的方式，可能可以成為預防早產兒呼吸窘迫症侯群一個嶄新的方式。Notch 訊息，尤其是Dll4/Notch 訊息被發現會透過調控VEGF/VEGFR2 訊息而調控血管的新生。VEGF/VEGFR2 會導致血管內皮細胞Dll4 表現量增加，而抑制Dll4/Notch訊息則反過來會增加VEGFR2 的表現進而活化VEGF 訊息，最後促進血管的新生。因此，我們的假說為產前抑制胎鼠Dll4 訊息將可活化VEGF 的訊息，進而促進胎鼠肺臟的成熟。本研究的目標為：1. 瞭解在體外及活體上產前類固醇促進肺成熟的機制中，對肺泡上皮細胞以及胎鼠肺臟中Notch 以及VEGF 家族成員表現的影響為何。2. 了解 Dll4/Notch 訊息如何去調控VEGF/VEGFR2 訊息以及肺臟表面張力素(surfactant)的表現。另外，經由子宮內注射anti-Dll4 抗體去瞭解是否可以促進胎鼠肺臟的成熟。3. 另一方面，在體外以及經由子宮內注射合成的小鼠Dll4 蛋白來活化Dll4/Notch 訊息，藉此想看(相反的)活化Dll4 訊息，是否會相反地抑制肺臟的成熟。4. 最後，想知道產前給予懷孕母鼠 anti-Dll4 抗體是否可以通過胎盤進而促進胎鼠肺臟的成熟。我們的初步結果証實子宮內注射anti-Dll4 抗體確實會促進胎鼠肺部的成熟。我們希望能透過這個四年期的計劃，去瞭解Notch/VEGF 訊息對胎鼠肺臟成熟的影響與機轉。最後，若產前給予母親anti-Dll4 抗體真的如我們假說一樣可以有效的預防早產小鼠呼吸窘迫的症狀，那將來將可提供臨床一個非類固醇的嶄新療法去預防早產兒的呼吸窘迫症候群。<br> Abstract: Respiratory distress syndrome (RDS), previously called hyaline membrane disease, is acommon cause of morbidity and mortality in premature infants. The incidence is 56-60% ininfants born between 24 and 28 weeks of gestation and decreases with increasing gestationalage (GA). The development of RDS in premature infants is correlated with surfactantdeficiency. Antenatal corticosteroid to promote lung maturation showed remarkable efficacyin either preventing or reducing the severity of RDS. However, there are still several concernsabout the side effect of antenatal corticosteroid including infection, intrauterine growthretardation, and even bronchopulmonary dysplasia.Recently, Compernolle et al. showed that hypoxia-inducible transcription factor-2(HIF-2) and its downstream target vascular endothelial growth factor (VEGF) were criticalfor fetal lung maturation in an animal study. Furthermore, intrauterine delivery or postnatalintratracheal instillation of VEGF stimulated conversion of glycogen to surfactant andprotected preterm mice against RDS. However, intrauterine VEGF injection is dangerous forfetus with preterm labor and antenatal VEGF therapy is very difficult due to its largemolecular weight that prohibit it delivered through placenta. Therefore, to find a way tostimulate fetal pulmonary VEGF expression maybe a novel therapy to replace antenatalsteroid treatment in preventing neonatal RDS.Notch signaling, especially Dll4/Notch signaling, plays an important role in controllingangiogenesis through regulating VEGF/VEGFR2 pathway. VEGF/VEGFR2 caused increasedDll4 expression in endothelium. Blocking of Notch signaling by anti-Dll4 antibody resulted inupregulation of VEGFR2 expression in endothelium that leaded to promoted anigogenesisthrough activating VEGF signaling. We hypothesize that antenatal anti-Dll4 therapy maypromote fetal lung maturation through activating VEGF signaling.Specific Aims:1. The effect of antenatal corticosteroid on the pulmonary expression of Notchcomponents and VEGF family both in vitro and in vivo2. Role of Dll4/Notch signaling in VEGF/VEGFR2 and surfactant proteins expressionin vitro and disruption of fetal Dll4 on lung maturation in vivo3. The in vitro and in vivo effect of activating Dll4/Notch signaling by intra-uterineinjection of recombinant Dll4 protein on fetal lung maturation4. The effect of maternal anti-Dll4 injection in fetal lung maturationOur preliminary data supported that intrauterine anti-Dll4 therapy promoted fetal lungmaturation. We hope this four-year grant can elucidate the role of Notch-VEGF signalpathway in fetal lung maturation. In addition, if antenatal anti-Dll4 antibody therapy reallypromotes fetal lung maturation, we can use this novel therapy to replace antenatalcorticosteroid that can prevent RDS and avoid the side effect of corticosteroid.